"This requires rapid and precise information that 'reports' the perturbation," Richardson said.
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The experiment is called Scopex, which stands for Stratospheric Controlled Perturbation Experiment.
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Another trick used by NeoFace is what NEC calls the Perturbation Space Method.
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Dr Cuk's explanation relies on another form of orbital perturbation called an evection.
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Usage also needs to cover perturbation, masking, and purpose-based access to data.
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Selina, much to Amy's perturbation, decides to send Richard along as Bob's number two.
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That outcome is called a perturbation effect, and is related to how these animals congregate.
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Theoretically, a sensitive enough instrument could detect that very slight perturbation, signaling that these gravitational waves exist.
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"So both the extrinsic perturbation and the intrinsic properties of the system are important to know," Xavier said.
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It takes hugely energetic events — like the collision of black holes or neutron stars — to generate a measurable perturbation.
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However, as long as the Suez Canal is not closed to ships from Qatar, the perturbation will be minor.
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One type of adversarial image — referred to by researchers as a "perturbation" — is all but invisible to the human eye.
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We tend to think of the art of Classical Greece, with its buff Apollos and poised Aphrodites, as beyond perturbation.
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In their models, macroeconomists get such episodes going by introducing a "shock": a random perturbation which knocks an economy off kilter.
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"We just kind of launch them and let them decay with as little perturbation of the orbit as possible," Webb says.
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Museums & Galleries We tend to think of the art of Classical Greece, with its buff Apollos and poised Aphrodites, as beyond perturbation.
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But then you add a "perturbation" to the image — a layer of pixels that changes how the system reads the underlying image.
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It was a deeper sensation, a vibration of the sixth sense, a perturbation of internal harmonies that indicated the presence of a tuber.
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Someone is going to make a greedy merge—something is going to cause enough of a traffic perturbation to result in a network breakdown.
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The slightest perturbation — an imperfection in the shape, a tilt in the angle of the wing, a gust of wind — disrupts the smooth flow.
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But nothing beats a field test, which is where Keutsch and his crew have their sights set next with a Stratospheric Controlled Perturbation Experiment (SCoPEx).
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Ms. Martinez speak-sings at a pace that recalls the blues but with an affect that suggests perturbation or getting stunned or sweating, or all three.
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The ensuing gravitational perturbation caused the parent planet to enter into a wildly eccentric orbit that placed it on a collision course with the host star.
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One of her recent papers looks at how you can identify a perturbation overlaid on an image by checking for consistency between different patches of the image.
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Despite the fact that Charlie supported O'Brien far more heavily than he supported Selina, the two instantly start flirting, much to the perturbation of the overly protective Gary.
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For weeks, the president has had his acting chief of staff, Mick Mulvaney, scrounging under agency sofa cushions for unspent cash, to the perturbation of even fellow Republicans.
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Second, you often — but not always — need access to the internal code of the system you're trying to manipulate in order to generate the perturbation in the first place.
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For example, the whole idea of using "perturbation theory" and series expansions that has existed since the 1700s in celestial mechanics is now also core to quantum field theory.
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The strategy reveals that quantum measurement is not about the physical perturbation induced by the probe but about what you know (and what you leave unknown) as a result.
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From left to right: Unmodified image of a dog, adversarial image in which the dog is made to look like a cat, and a control image where the perturbation is flipped.
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This creates a feedback mechanism in which a tiny perturbation—a single driver braking unexpectedly—will send little ripples of corresponding slowdowns through the entire chain of cars behind him/her.
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Even the smallest perturbation to a complex system (like the weather, the economy or just about anything else) can touch off a concatenation of events that leads to a dramatically divergent future.
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It wasn't as big a deal as the asteroid that took out the dinosaurs and almost everything else, but it was the biggest perturbation since then—at least before humans came along.
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"It's our history, it's the Earth's history, and if we perturb it we don't know how fast it will recover, or what influence the perturbation would have on ocean chemistry," she said.
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The trillions of microbes "undergo many changes during the period between birth and ages 3 to 4, and are highly susceptible to perturbation by the kinds of exposures listed above," Berger writes.
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I had an intimation of the fragility of the bled al-makhzen — the sphere men create to keep at a safe distance the perturbation beyond, should one step through the wrong open door.
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Since adversarial attackers will have no way of knowing which patches of the image you're going to test for consistency, it'll theoretically be hard for them to design a perturbation that evades detection.
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And then at a global level, you don't want the [climate] perturbation, because it gets you off into a level of uncertainty both about weather and the knock-on effects for ecosystems and species.
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"Fall risk is markedly increased in people who cannot successfully respond to a postural perturbation (such as a trip or slip, ankle turn) in the roughly 400 milliseconds available to do so," Richardson said by email.
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To test its effectiveness on humans, experiments were run in which participants were shown an unmodified photo, an adversarial photo that fooled 100 percent of CNNs, and a photo with the perturbation layer flipped (the control).
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But the new experiment — called the Stratospheric Controlled Perturbation Experiment and led by Harvard researchers Frank Keutsch, David Keith, John Dykema, and Lizzie Burns — aims to offer an actual, in-atmosphere test of what artificial geoengineering would do.
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Metastable liquids have found a little nook in the laws of physics where they can stay liquid-like—but like a spinning plate balancing on a stick, any perturbation and the atoms zip back into a solid form.
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What the Swiss researchers are saying is that, given the introduction of their perturbation, we can have two nearly identical images of a dog—nigh indistinguishable to the human eye—and wind up with dramatically different predictions from the image classifier.
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This required the addition of "human-meaningful features," such as altering the edges of objects, enhancing edges by adjusting contrast, messing with the texture, and taking advantage of dark regions in a photo that can amplify the effect of a perturbation.
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We sat there, enthralled as he introduced his theory of plot ("the gradual perturbation of an unstable homeostatic system and its catastrophic restoration to a new and complexified equilibrium") or compared the structure of dramatic action to a love affair.
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A successful de-identification strategy, as captured by both the CCPA and the FTC recommendations, is the control of downstream data usage through contractual obligations, auditing, and the range of techniques applied on the data in order to better balance utility and data perturbation.
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The way to mess with AI, as these examples illustrate, is to introduce a so-called "perturbation" within the image, whether it be a misplaced pixel, a toaster, or patterns of white noise that, while invisible to humans, can convince a bot into thinking a panda is a gibbon.
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Color afterimages, the "impossible colors" (reddish greens) that arise by stabilizing the eye, and color experiences that emerge from direct electrical perturbation of the brain, are other ways in which we have experienced new color phenomenon, not by developing new stimuli but by an understanding of how the brain processes vision.
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Both of today's Alfredos, sadly, are touristy and overpriced, though Il Vero is almost worth a visit for the hundreds of framed photos of the owners mock-feeding giant handfuls of fettuccine to celebrity visitors whose expressions range from hammy complicity (James Stewart, Sylvester Stallone) to perturbation bordering on panic (Peter Sellers, Sophia Loren).
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The usual disciplines are explored: ESP, clairvoyance, traveling clairvoyance (or out-of-body experiences), psychometry (divining information from objects), skin reading, dowsing, eyeless sight, mental telepathy, synthetic telepathy (using microwaves), outbounder-beaconry (don't ask), mind projection, psychoenergetics, remote viewing, E.H.B.F. (extraordinary human body function), spoon bending, remote action, remote perturbation (a gentler version of the former), precognition, divination, automatic writing, cryptomnesia (unconsciously evoking latent memories) and premonition/intuition (a.k.a.
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The devastating toll on native Australian species from the introduction of the cane toad should be a grim wakeup call about the fate that likely awaits Madagascar&aposs native predators, should the Asian common toad continue to spread unchecked, according to study co-author Wolfgang Wüster, a herpetologist and senior lecturer in zoology at Bangor University in the U.K. "In Australia, the introduction of cane toads has caused profound perturbation to many ecosystems by removing key predators from local food webs with their toxins," Wüster said in a statement.
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The standard exposition of perturbation theory is given in terms of the order to which the perturbation is carried out: first-order perturbation theory or second-order perturbation theory, and whether the perturbed states are degenerate, which requires singular perturbation. In the singular case extra care must be taken, and the theory is slightly more elaborate.
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The more basic of these include the method of matched asymptotic expansions and WKB approximation for spatial problems, and in time, the Poincaré–Lindstedt method, the method of multiple scales and periodic averaging. For books on singular perturbation in ODE and PDE's, see for example Holmes, Introduction to Perturbation Methods,Holmes, Mark H. Introduction to Perturbation Methods. Springer, 1995. Hinch, Perturbation methodsHinch, E. J. Perturbation methods.
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Many of the ab initio quantum chemistry methods use perturbation theory directly or are closely related methods. Implicit perturbation theory works with the complete Hamiltonian from the very beginning and never specifies a perturbation operator as such. Møller-Plesset perturbation theory uses the difference between the Hartree-Fock Hamiltonian and the exact non- relativistic Hamiltonian as the perturbation. The zero-order energy is the sum of orbital energies.
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Acoustic Perturbation Equations Refer to the paper "Acoustic Perturbation Equations Based on Flow Decomposition via Source Filtering" by R.Ewert and W.Schroder.
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20, no. 4, pp. 774–780, 1972 and the vector perturbation technique.B. M. Hochwald, C. B. Peel, and A. L. Swindlehurst, A vector-perturbation technique for near-capacity multiantenna multi-user communication - Part II: Perturbation, IEEE Transactions on Communications, vol.
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In mathematical optimization, the perturbation function is any function which relates to primal and dual problems. The name comes from the fact that any such function defines a perturbation of the initial problem. In many cases this takes the form of shifting the constraints. In some texts the value function is called the perturbation function, and the perturbation function is called the bifunction.
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Chernoff bounds can be effectively used to evaluate the "robustness level" of an application/algorithm by exploring its perturbation space with randomization.C.Alippi: "Randomized Algorithms" chapter in Intelligence for Embedded Systems. Springer, 2014, 283pp, . The use of the Chernoff bound permits one to abandon the strong -and mostly unrealistic- small perturbation hypothesis (the perturbation magnitude is small).
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Regular perturbation analysis for a flow around a cylinder with slight perturbation in the configurations can be found in Milton Van Dyke (1975). In the following, will represent a small positive parameter and is the radius of the cylinder. For more detailed analyses and discussions, readers are referred to Milton Van Dyke's 1975 book Perturbation Methods in Fluid Mechanics.
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Phase perturbation is the shifting, from whatever cause, in the phase of an electronic signal. The shifting is often quite rapid, and may appear to be random or cyclic. The phase departure in phase perturbation usually is larger, but less rapid, than in phase jitter. Phase perturbation may be expressed in degrees, with any cyclic component expressed in hertz.
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It is possible to treat the equation using perturbation theory.
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Unfortunately, MCSCF based methods are not without perturbation series divergences.
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Krylov–Bogoliubov averaging can be used to approximate oscillatory problems when a classical perturbation expansion fails. That is singular perturbation problems of oscillatory type, for example Einstein's correction to the perihelion precession of Mercury.
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Many problems in his books stress this property of perturbation theory.
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Since there is no function a priori that tells which one is the most suitable value for our perturbation, the best criteria is to get it adaptive. For instance Battiti and Protasi proposed a reactive search algorithm for MAX-SAT which fits perfectly into the ILS. framework. They perform a “directed” perturbation scheme which is implemented by a tabu search algorithm and after each perturbation they apply a standard local descent algorithm. Another way of adapting the perturbation is to change deterministically its strength during the search.
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Omohundro's book Geometric Perturbation Theory in PhysicsStephen M. Omohundro, Geometric Perturbation Theory in Physics, World Scientific Publishing Co. Pte. Ltd., Singapore (1986) 560 pages. describes natural Hamiltonian symplectic structures for a wide range of physical models that arise from perturbation theory analyses. He showed that there exist smooth partial differential equations which stably perform universal computation by simulating arbitrary cellular automata.
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An inward radial perturbation causes the perturbed body to get closer to all other objects, increasing the force on the object and increasing its orbital velocity—which leads indirectly to a tangential perturbation and the argument above.
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The equations below are valid for equally spaced measurements of the perturbation.
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Perturbation theory has been used in a large number of different settings in physics and applied mathematics. Examples of the "collection of equations" D include algebraic equations,L. A. Romero, "Perturbation theory for polynomials", Lecture Notes, University of New Mexico (2013) differential equations (e.g., the equations of motion Sergei Winitzki, "Perturbation theory for anharmonic oscillations", Lecture notes, LMU (2006) and commonly wave equations), thermodynamic free energy in statistical mechanics, radiative transfer, Michael A. Box, "Radiative perturbation theory: a review", Environmental Modelling & Software 17 (2002) 95–106 and Hamiltonian operators in quantum mechanics.
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In perturbation theory, the Poincaré–Lindstedt method or Lindstedt–Poincaré method is a technique for uniformly approximating periodic solutions to ordinary differential equations, when regular perturbation approaches fail. The method removes secular terms—terms growing without bound—arising in the straightforward application of perturbation theory to weakly nonlinear problems with finite oscillatory solutions., pp. 181–186. The method is named after Henri Poincaré,, §123–§128.
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SSA perturbation theory is developed in Nekrutkin (2010) and Hassani et al. (2011).
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Oxysternon festivum lives in forest but can tolerate certain degree of habitat perturbation.
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First-order perturbation theory also leads to matrix eigenvalue problem for degenerate states.
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2D correlation analysis originated from 2D NMR spectroscopy. Isao Noda developed perturbation based 2D spectroscopy in the 1980s. This technique required sinusoidal perturbations to the chemical system under investigation. This specific type of the applied perturbation severely limited its possible applications.
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A stable point is such that a small perturbation of the system will be diminished and the system will come back to the original point. On the other hand, if a small perturbation is magnified, the stationary point is considered unstable.
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Thus, they cannot be treated as a small perturbation around the explicit symmetry limit.
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Cavity perturbation theory describes methods for derivation of perturbation formulae for performance changes of a cavity resonator. These performance changes are assumed to be caused by either introduction of a small foreign object into the cavity or a small deformation of its boundary.
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Modulation instability only happens under certain circumstances. The most important condition is anomalous group velocity dispersion, whereby pulses with shorter wavelengths travel with higher group velocity than pulses with longer wavelength. (This condition assumes a focussing Kerr nonlinearity, whereby refractive index increases with optical intensity.) The instability is strongly dependent on the frequency of the perturbation. At certain frequencies, a perturbation will have little effect, whilst at other frequencies, a perturbation will grow exponentially.
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Newtonian-like equations emerge from perturbative general relativity with the choice of the Newtonian gauge; the Newtonian gauge provides the direct link between the variables typically used in the gauge- invariant perturbation theory and those arising from the more general gauge- invariant covariant perturbation theory.
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Each interaction can be visually represented by Feynman diagrams according to perturbation theory in quantum mechanics.
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Simulations of this system (or a simple linear perturbation analysis) demonstrate that such systems are unstable: any motion away from the perfect geometric configuration causes an oscillation, eventually leading to the disruption of the system (Klemperer's original article also states this fact). This is the case whether the center of the rosette is in free space, or itself in orbit around a star. The short-form reason is that any perturbation destroys the symmetry, which increases the perturbation, which further damages the symmetry, and so on. The longer explanation is that any tangential perturbation brings a body closer to one neighbor and further from another; the gravitational imbalance becomes greater towards the closer neighbor and less for the farther neighbor, pulling the perturbed object further towards its closer neighbor, amplifying the perturbation rather than damping it.
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This resembles the Born approximation, in that the details of the problem are treated as a perturbation.
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The modern theory of frozen orbits is based on the algorithm given in a 1989 article by Mats Rosengren. For this the analytical expression () is used to iteratively update the initial (mean) eccentricity vector to obtain that the (mean) eccentricity vector several orbits later computed by the precise numerical propagation takes precisely the same value. In this way the secular perturbation of the eccentricity vector caused by the J_2\, term is used to counteract all secular perturbations, not only those (dominating) caused by the J_3\, term. One such additional secular perturbation that in this way can be compensated for is the one caused by the solar radiation pressure, this perturbation is discussed in the article "Orbital perturbation analysis (spacecraft)".
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In a perturbation-series approach, this easily gives rise to a spurious secular variation of the solution, in contradiction with the periodic behaviour of the waves. Stokes solved this problem by also expanding the dispersion relationship into a perturbation series, by a method now known as the Lindstedt–Poincaré method.
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Also called 'Acoustic Analogy'. To obtain Lighthill's aeroacoustic analogy the governing Navier-Stokes equations are rearranged. The left hand side is a wave operator, which is applied to the density perturbation or pressure perturbation respectively. The right hand side is identified as the acoustic sources in a fluid flow, then.
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Borel summation finds application in perturbation expansions in quantum field theory. In particular in 2-dimensional Euclidean field theory the Schwinger functions can often be recovered from their perturbation series using Borel summation . Some of the singularities of the Borel transform are related to instantons and renormalons in quantum field theory .
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The high electronegativity of the oxygen results in strong single perturbation by one heteroatom in the six-membered ring.
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Using vibrational perturbation theory, effects such as tunnelling and variational effects can be accounted for within the SCTST formalism.
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Radii of curvature in a thread undergoing the breakup process. Blue represents the first radius of curvature and red the second radius of curvature at the thinned and thickened locations. The wavelength of the perturbation is therefore the critical parameter in determining whether a given fluid thread will breakup into smaller masses of fluid. Rigorous mathematical examination of the perturbation wavelengths can lead to a relation showing which wavelengths are stable for a given thread as well as which perturbation wavelengths will grow most rapidly.
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A flavor of the k·p perturbation theory used for calculating the structure of multiple, degenerate electronic bands in bulk and quantum well semiconductors. The method is a generalization of the single band k·p theory. In this model the influence of all other bands is taken into account by using Löwdin's perturbation method.
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The solution u=u(p) stiffness matrix K=K(p) and the load vector Q=Q(p) can be expanded by using perturbation theory. Perturbation theory lead to the approximate value of the interval solution [Qiu, Elishakoff 1998]. The method is very efficient and can be applied to large problems of computational mechanics.
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Next a trial structure is created by displacing some of the atoms. If the displacements are small the trial structure can be considered as a small perturbation of the reference structure and first-order perturbation theory can be used to determine the I–V curves of a large set of trial structures.
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The first explanation of the attraction between noble gas atoms was given by Fritz London in 1930. and . English translations in He used a quantum-mechanical theory based on second-order perturbation theory. The perturbation is because of the Coulomb interaction between the electrons and nuclei of the two moieties (atoms or molecules).
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Interventions involving resistance training along with perturbation training may prove to be beneficial in improving muscle strength and balance recovery.
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Data perturbation has been hailed as one of the most effective data protection techniques, whilst being relatively simple to implement.
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Each coil requires separate tolerance and some certain perturbation combinations, permitting greater coil tolerances, which could reduce time and cost.
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There is convincing demonstration that the observed masses are compatible with chiral perturbation theory. The internal consistency of this argument is further checked by lattice QCD computations which allow one to vary the quark mass and check that the variation of the pseudoscalar masses with the quark mass is as required by chiral perturbation theory.
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320, pp. 418-420, 2008. ,, (arXiv Submission) The fermions in the fluid that take part in the screening cannot be considered as a point entity but a wave-vector is required to describe them. Charge density away from the perturbation is not a continuum but fermions arrange themselves at discrete spaces away from the perturbation.
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During the starting point of the uses of perturbation theory, the applications using the method were based on nondegenerate many- body perturbation theory (MBPT). MBPT is a reasonable method for atomic and molecular system which a single non-degenerate Slater determinant can represent zeroth-order electronic description. Therefore, MBPT method would exclude atomic and molecular states, especially excited states, which cannot be represented in zeroth order as single Slater determinants. Moreover, the perturbation expansion would converges very slowly or not at all if the state is degenerate or near degenerate.
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In 1980 Fleishman and Anderson demonstrated the phenomenon survived the addition of interactions to lowest order in perturbation theory. In a 1998 study, the analysis was extended to all orders in perturbation theory, in a zero dimensional system, and the MBL phenomenon was shown to survive. In 2005 and 2006, this was extended to high orders in perturbation theory in high dimensional systems. MBL was argued to survive at least at low energy density. A series of numerical works provided further evidence for the phenomenon in one dimensional systems, at all energy densities (“infinite temperature”).
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By exploiting gauge invariance, certain properties of the perturbation metric can be guaranteed by choosing a suitable vector field \xi^\mu.
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However, both methods require detaching cells from their microenvironments first, thereby causing perturbation to the transcriptional profiles in RNA expression analysis.
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Effects of kinesio tape compared with nonelastic sports tape and the untaped ankle during a sudden inversion perturbation in male athletes.
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In the early 1960s, the perturbation theory in quantum chemical applications was introduced. Since, there has been a wide spread of uses of the theory through software such as Gaussian. The perturbation theory correlation method is used routinely by the non-specialists. This is because it can easily achieve the property of size extensivity comparing to other correlation methods.
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These well-developed perturbation methods were adopted and adapted to solve new problems arising during the development of quantum mechanics in 20th century atomic and subatomic physics. Paul Dirac developed quantum perturbation theory in 1927 to evaluate when a particle would be emitted in radioactive elements. This was later named Fermi's golden rule. See equations (24) and (32).
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Resistance and inertia deal with a system's inherent response to some perturbation. A perturbation is any externally imposed change in conditions, usually happening in a short time period. Resistance is a measure of how little the variable of interest changes in response to external pressures. Inertia (or persistence) implies that the living system is able to resist external fluctuations.
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In quantum mechanics, particularly Perturbation theory, a transition of state is a change from an initial quantum state to a final one.
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The perturbation strength has to be sufficient to lead the trajectory to a different attraction basin leading to a different local optimum.
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In mathematics, the Melnikov method is a tool to identify the existence of chaos in a class of dynamical systems under periodic perturbation.
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Such estimation is based on perturbation theory analysis. Therefore, CISD calculations with the Davidson correction included are frequently referred to as CISD(Q).
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His main research interests are Krylov subspace methods, non-normal operators and spectral perturbation theory, Toeplitz matrices, random matrices, and damped wave operators.
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The culmination of his perturbation was the recall of Ambassador Yovanovitch, which he and numerous other career diplomats saw as unjustifiable and punitive.
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The major difference between SAPT and supermolecular EDA methods is that, as the name suggests, SAPT computes the interaction energy directly via a perturbative approach. One consequence of capturing the total interaction energy as a perturbation to the total system energy rather than using the subtractive supermolecular method outlined above, is that the interaction energy is made free of BSSE in a natural way. Being a perturbation expansion, SAPT also provides insight into the contributing components to the interaction energy. The lowest-order expansion at which all interaction energy components are obtained is second-order in the intermolecular perturbation.
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In mathematics and physics, perturbation theory comprises mathematical methods for finding an approximate solution to a problem, by starting from the exact solution of a related, simpler problem. A critical feature of the technique is a middle step that breaks the problem into "solvable" and "perturbative" parts. Perturbation theory is widely used when the problem at hand does not have a known exact solution, but can be expressed as a "small" change to a known solvable problem. Perturbation theory is used in a wide range of fields, and reaches its most sophisticated and advanced forms in quantum field theory.
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One of the colleagues of Krivchenkov, Yurii Shirokov tried to construct quantum field theory in terms of wave packets, without divergences, using the algebra of generalized functions, but even now this approach is not sufficiently developed. Krivchenkov told students that they are supposed to build up a "true" theory, not just a perturbation, that always gives a divergent series. This statement (dogma) applies not only to Field Theory and quantum mechanics, but to any perturbation theory with respect to any distributed system; the perturbation series always diverges. Krivchenkov had realized this and brought this knowledge to students.
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Cavity losses coherence due to dephasing. In physics, dephasing is a mechanism that recovers classical behaviour from a quantum system. It refers to the ways in which coherence caused by perturbation decays over time, and the system returns to the state before perturbation. It is an important effect in molecular and atomic spectroscopy, and in the condensed matter physics of mesoscopic devices.
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The Adomian decomposition method, the Lyapunov artificial small parameter method, and his homotopy perturbation method are all special cases of the more general homotopy analysis method. These are series expansion methods, and except for the Lyapunov method, are independent of small physical parameters as compared to the well known perturbation theory, thus giving these methods greater flexibility and solution generality.
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In theory of vibrations, Duhamel's integral is a way of calculating the response of linear systems and structures to arbitrary time-varying external perturbation.
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However, it has been found that different ligand environments of complexes can still affect metabolism and uptake, introducing an unwelcome perturbation in cellular function.
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Perturbation theory for quantum mechanics imparts the first step on this path. The field in general remains actively and heavily researched across multiple disciplines.
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Excited states are often calculated using coupled cluster, Møller–Plesset perturbation theory, multi-configurational self-consistent field, configuration interaction, and time-dependent density functional theory.
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However, a perturbation in the other coefficients (all equal to zero) will slightly change the roots. Therefore, Wilkinson's polynomial is well-conditioned in this basis.
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Cole continued to delve deeper into this topic for the next decade. Cole took sabbatical in 1963-1964 at Harvard, where he wrote a book on this body of work: Perturbation Methods in Applied Mathematics.Kevorkian, J. and Cole, J.D. (1981) Perturbation Methods in Applied Mathematics, Springer-Verlag, 2nd Ed. Cole is the namesake of the Society for Industrial and Applied Mathematics's Julian Cole Lectureship.
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Chiral perturbation theory (ChPT) is an effective field theory constructed with a Lagrangian consistent with the (approximate) chiral symmetry of quantum chromodynamics (QCD), as well as the other symmetries of parity and charge conjugation. Heinrich Leutwyler (2012), Chiral perturbation theory, Scholarpedia, 7(10):8708. ChPT is a theory which allows one to study the low- energy dynamics of QCD on the basis of this underlying chiral symmetry.
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The shift in absorption lines can be calculated by comparing the energy levels in unbiased and biased quantum wells. It is a simpler task to find the energy levels in the unbiased system, due to its symmetry. If the external electric field is small, it can be treated as a perturbation to the unbiased system and its approximate effect can be found using perturbation theory.
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Among his most significant contributions are the development of much improved equations of state for complex fluids and fluid mixtures, based on statistical mechanical perturbation theory. During the 1960s Barker, Henderson and others had developed a successful perturbation theory for liquids composed of spherical molecules. While this was a milestone, such simple liquids play very almost no role in chemical engineering processes, which involve mixtures containing molecules that are non-spherical, polar, associating and so on. In 1972 Keith, together with Chris Gray of Guelph, proposed a perturbation theory for liquids of non- spherical molecules, and then applied it to more complex mixtures, including polar liquids.
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The following treatment is fairly common in literature (though here it's slightly adapted), and often referred as time- dependent perturbation theory in a more advanced form.
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This trend is compatible with a perturbation by a planet of less than 12 Earth masses on an orbit within about 0.08 AU of the star.
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In successful sublimation, Sullivan observed extraordinarily efficient handling of a conflict between the need for a satisfaction and the need for security without perturbation of awareness.
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Sachrajda earned his doctorate from Imperial College London in 1974. His thesis was entitled Applications of perturbation theory to the high energy scattering of elementary particles.
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Some important examples of physical situations where degenerate energy levels of a quantum system are split by the application of an external perturbation are given below.
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However, the vacuum carries no charge. Hence all the gauge symmetries are unbroken. Corrections for the masses of the quarks can be incorporated using chiral perturbation theory.
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The size of the fluid masses resulting from the breakup of a fluid thread can be approximated by the wavelengths of the perturbation that grow most rapidly.
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By analyzing the perturbation of Kugultinov's orbit due to the gravitational pull of Themis, the mass of Themis was determined to be approximately solar masses ( Earth masses).
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Classical observer only concerns system state. ESO observes system state and external disturbance. It can also estimate unknown model's perturbation. Hence, ADRC isn't dependent on mathematic model.
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The Kolmogorov–Arnold–Moser (KAM) theorem is a result in dynamical systems about the persistence of quasiperiodic motions under small perturbations. The theorem partly resolves the small-divisor problem that arises in the perturbation theory of classical mechanics. The problem is whether or not a small perturbation of a conservative dynamical system results in a lasting quasiperiodic orbit. The original breakthrough to this problem was given by Andrey Kolmogorov in 1954.
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The physical size of the Hubble radius (solid line) as a function of the linear expansion (scale factor) of the universe. During cosmological inflation, the Hubble radius is constant. The physical wavelength of a perturbation mode (dashed line) is also shown. The plot illustrates how the perturbation mode grows larger than the horizon during cosmological inflation before coming back inside the horizon, which grows rapidly during radiation domination.
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Møller–Plesset perturbation theory (MP) is one of several quantum chemistry post–Hartree–Fock ab initio methods in the field of computational chemistry. It improves on the Hartree–Fock method by adding electron correlation effects by means of Rayleigh–Schrödinger perturbation theory (RS-PT), usually to second (MP2), third (MP3) or fourth (MP4) order. Its main idea was published as early as 1934 by Christian Møller and Milton S. Plesset.
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Expanding in g and computing the functional derivatives, we are able to obtain all the n-point functions with perturbation theory. Using LSZ reduction formula we get from the n-point functions the corresponding process amplitudes, cross sections and decay rates. The theory is renormalizable and corrections are finite at any order of perturbation theory. For quantum electrodynamics the ghost field decouples because the gauge group is abelian.
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Positive feedback (exacerbating feedback, self-reinforcing feedback) is a process that occurs in a feedback loop which exacerbates the effects of a small disturbance. That is, the effects of a perturbation on a system include an increase in the magnitude of the perturbation. That is, A produces more of B which in turn produces more of A.Keesing, R.M. (1981). Cultural anthropology: A contemporary perspective (2nd ed.) p.149.
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In a flat disk of objects with eccentric orbits a small initial vertical perturbation is amplified by the inclination instability. The initial perturbation exerts an vertical force. On very long timescales relative to the period of an object's orbit this force produces a net torque on the orbit due to the object spending more time near aphelion. This torque causes the plane of the orbit to roll on its major axis.
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Thermodynamic perturbation-theory and integral-equations, J. Stat. Phys., vol. 35(1-2), 35-47, (1984). Times Cited: 1,051 # Wertheim, MS, Fluids with highly directional attractive forces. 4.
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Wenquan Che; Zhanxian Wang; Yumei Chang; Russer, P.; "Permittivity Measurement of Biological Materials with Improved Microwave Cavity Perturbation Technique," Microwave Conference, 2008. EuMC 2008. 38th European, vol., no.
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Another example occurs for the Ising model with random-field disorder, where the fixed point occurs at zero temperature, and the temperature perturbation is dangerously irrelevant ( p. 164).
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Introducing this weak perturbation has significant effects on the solution to the Schrödinger equation, most significantly resulting in a band gap between wave vectors in different Brillouin zones.
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Some perturbation solutions in laminar boundary-layer theory. Journal of Fluid Mechanics, 17(3), 433-449.. Moffatt eddies are also a self-similar solution of the second kind.
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For a sufficiently small perturbation of a certain nonlinear oscillator or a network of coupled oscillators, we can compute the corresponding phase sensitivity function or infinitesimal PRC Z(\varphi).
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Schrödinger, Quantisierung als Eigenwertproblem, Annalen der Physik, vol. 385 Issue 13, 437–490 (1926) on quantum theory (in which he introduced his perturbation theory), once in the manner of the 1916 work of Epstein (but generalized from the old to the new quantum theory) and once by his (first- order) perturbation approach. Finally, EpsteinP. S. Epstein, The Stark Effect from the Point of View of Schroedinger's Quantum Theory, Physical Review, vol 28, pp.
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Chan and Dickinson (1998) suggested that what the fly does to prevent this from occurring is to first move its halteres as if it were being pushed in the opposite direction that it wants to go. The fly has not moved, but the halteres have sensed a perturbation. This would allow the haltere-initiated reflex to occur, correcting the imagined perturbation. The fly would then be able to execute its turn in the desired direction.
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Of the five simplifications outlined in the section "Hartree–Fock algorithm", the fifth is typically the most important. Neglect of electron correlation can lead to large deviations from experimental results. A number of approaches to this weakness, collectively called post-Hartree–Fock methods, have been devised to include electron correlation to the multi-electron wave function. One of these approaches, Møller–Plesset perturbation theory, treats correlation as a perturbation of the Fock operator.
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In quantum chemistry, n-electron valence state perturbation theory (NEVPT) is a perturbative treatment applicable to multireference CASCI-type wavefunctions. It can be considered as a generalization of the well-known second-order Møller–Plesset perturbation theory to multireference Complete Active Space cases. The theory is directly integrated into many quantum chemistry packages such as MOLCAS, Molpro, DALTON and ORCA. The research performed into the development of this theory led to various implementations.
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This situation signals a breakdown of perturbation theory: it stops working at this point, and cannot be expanded or summed any further. In formal terms, the perturbative series is a asymptotic series: a useful approximation for a few terms, but ultimately inexact. The breakthrough from chaos theory was an explanation of why this happened: the small divisors occur whenever perturbation theory is applied to a chaotic system. The one signals the presence of the other.
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Phase-transition processes can also be explained in terms of spinodal decomposition, where phase separation is delayed until the system enters the unstable region where a small perturbation in composition leads to a decrease in energy and, thus, spontaneous growth of the perturbation. This region of a phase diagram is known as the spinodal region and the phase separation process is known as spinodal decomposition and may be governed by the Cahn–Hilliard equation.
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Quantum field theory is a generalization of quantum mechanics. Krivchenkov believed that people need to understand at least the non–relativistic theory. He almost asked students to excuse him for the field theory, where only perturbation theory can be offered. Not only do the perturbation theory series diverge, but each perturbational term also in some sense is infinite, and a special renormalization of the interaction constant is required to give the result the physical sense.
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The natural orbitals of the perturbation expansion are a useful diagnostic for detecting intruder state effects. Sometimes what appears to be an intruder state is simply a change in basis.
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HDR and NHEJ repair double strand breaks. Other mechanisms such as NER (Nucleotide Excision Repair), BER (Base Excision Repair) and MMR recognise lesions and replace them via single strand perturbation.
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Nathalie Deruelle (born 1952) is a French physicist specializing in general relativity and known for her research on the two-body problem in general relativity and on cosmological perturbation theory.
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Perturbation series in quantum field theory are usually divergent as was firstly indicated by Freeman Dyson. According to the Lipatov method,L.N. Lipatov, Zh. Eksp. Teor. Fiz. 72, 411(1977) [Sov.Phys.
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Before its most recent passage through the Solar System, its orbital period was about 17,000 years, but the gravitational perturbation of the giant planets has increased this period to 70,000 years.
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Some applications are conveniently treated by perturbation theory, in which the system is considered as a two-body problem plus additional forces causing deviations from a hypothetical unperturbed two-body trajectory.
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In physics the survey of Yang–Mills theories does not usually start from perturbation analysis or analytical methods, but more recently from systematic application of numerical methods to lattice gauge theories.
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The KAM theorem quantifies the level of perturbation that can be applied for this to be true. Those KAM tori that are destroyed by perturbation become invariant Cantor sets, named Cantori by Ian C. Percival in 1979. The non-resonance and non-degeneracy conditions of the KAM theorem become increasingly difficult to satisfy for systems with more degrees of freedom. As the number of dimensions of the system increases, the volume occupied by the tori decreases.
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The predictive success of quantum electrodynamics largely rests on the use of perturbation theory, expressed in Feynman diagrams. However, quantum electrodynamics also leads to predictions beyond perturbation theory. In the presence of very strong electric fields, it predicts that electrons and positrons will be spontaneously produced, so causing the decay of the field. This process, called the Schwinger effect, cannot be understood in terms of any finite number of Feynman diagrams and hence is described as nonperturbative.
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Canadian Conference on, vol., no., pp.1486–1489, May 2006Wang, Z.H.; Javadi, H.H.S.; Epstein, A.J.; "Application of microwave cavity perturbation techniques in conducting polymers," Instrumentation and Measurement Technology Conference, 1991. IMTC-91.
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The perturbation in atmospheric 14C from the bomb testing was an opportunity to validate atmospheric transport models, and to study the movement of carbon between the atmosphere and oceanic or terrestial sinks.
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A transverse impulse (out of the orbital plane) causes rotation of the orbital plane without changing the period or eccentricity. In all instances, a closed orbit will still intersect the perturbation point.
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For critical applications the quartz oscillator is mounted in a temperature-controlled container, called a crystal oven, and can also be mounted on shock absorbers to prevent perturbation by external mechanical vibrations.
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He with Christian Møller are known for the Møller–Plesset perturbation theory. The Rayleigh-Plesset equation describing the dynamics of a bubble in an infinite body of fluid is also named after him.
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Instances of dirty paper coding include Costa precoding (1983). Suboptimal approximations of dirty paper coding include Tomlinson-Harashima precoding (THP) published in 1971 and the vector perturbation technique of Hochwald et al. (2005).
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For a Maclaurin spheroid of eccentricity greater than 0.812670, a Jacobi ellipsoid of the same angular momentum has lower total energy. If such a spheroid is composed of a viscous fluid, and if it suffers a perturbation which breaks its rotational symmetry, then it will gradually elongate into the Jacobi ellipsoidal form, while dissipating its excess energy as heat. This is termed secular instability. However, for a similar spheroid composed of an inviscid fluid, the perturbation will merely result in an undamped oscillation.
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The physical size of the Hubble radius (solid line) as a function of the scale factor of the universe. The physical wavelength of a perturbation mode (dashed line) is shown as well. The plot illustrates how the perturbation mode exits the horizon during cosmic inflation in order to reenter during radiation domination. If cosmic inflation never happened, and radiation domination continued back until a gravitational singularity, then the mode would never have exited the horizon in the very early universe.
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In practice, this process rapidly explodes into a profusion of terms, which become extremely hard to manage by hand. Isaac Newton is reported to have said, regarding the problem of the Moon's orbit, that "It causeth my head to ache.". This unmanageability has forced perturbation theory to develop into a high art of managing and writing out these higher order terms. One of the fundamental breakthroughs for controlling the expansion are the Feynman diagrams, which allow perturbation series to be written down diagrammatically.
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Perturbation theory in quantum mechanics is fairly accessible, as the quantum notation allows expressions to be written in fairly compact form, thus making them easier to comprehend. This resulted in an explosion of applications, ranging from the Zeeman effect to the hyperfine splitting in the hydrogen atom. Despite the simpler notation, perturbation theory applied to quantum field theory still easily gets out of hand. Richard Feynman developed the celebrated Feynman diagrams by observing that many terms repeat in a regular fashion.
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While auditory feedback is most important during speech acquisition, it may be activated less if the model has learned a proper feedforward motor command for each speech unit. But it has been shown that auditory feedback needs to be strongly coactivated in the case of auditory perturbation (e.g. shifting a formant frequency, Tourville et al. 2005).Tourville J, Guenther F, Ghosh S, Reilly K, Bohland J, Nieto-Castanon A (2005) Effects of acoustic and articulatory perturbation on cortical activity during speech production.
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The HAM distinguishes itself from various other analytical methods in four important aspects. First, it is a series expansion method that is not directly dependent on small or large physical parameters. Thus, it is applicable for not only weakly but also strongly nonlinear problems, going beyond some of the inherent limitations of the standard perturbation methods. Second, the HAM is a unified method for the Lyapunov artificial small parameter method, the delta expansion method, the Adomian decomposition method, and the homotopy perturbation method.
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The motion of the oscillating charge can be expressed as a Fourier series in the frequency of the oscillator. Heisenberg solved for the quantum behavior by two different methods. First, he treated the system with the virtual oscillator method, calculating the transitions between the levels that would be produced by the external source. He then solved the same problem by treating the anharmonic potential term as a perturbation to the harmonic oscillator and using the perturbation methods that he and Born had developed.
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Once the sandpile model reaches its critical state there is no correlation between the system's response to a perturbation and the details of a perturbation. Generally this means that dropping another grain of sand onto the pile may cause nothing to happen, or it may cause the entire pile to collapse in a massive slide. The model also displays 1/ƒ noise, a feature common to many complex systems in nature. This model only displays critical behaviour in two or more dimensions.
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For first published works, see references in The result was derived using ideas from the classical calculus of variations. After a slight perturbation of the optimal control, one considers the first- order term of a Taylor expansion with respect to the perturbation; sending the perturbation to zero leads to a variational inequality from which the maximum principle follows. Widely regarded as a milestone in optimal control theory, the significance of the maximum principle lies in the fact that maximizing the Hamiltonian is much easier than the original infinite-dimensional control problem; rather than maximizing over a function space, the problem is converted to a pointwise optimization. A similar logic leads to Bellman's principle of optimality, a related approach to optimal control problems which states that the optimal trajectory remains optimal at intermediate points in time.
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In 1980, he won the Norbert Wiener Prize in Applied Mathematics from AMS and SIAM. In 1970, he gave a plenary lecture at the ICM in Nice (scattering theory and perturbation of continuous spectra).
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9 (1958), 300–307. showed that the curve, if it exists, must be an analytic curve. In this deep paper, he correctly identified the problem as perturbation problem beyond all orders. # In 1966 EhrhartR.
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Russian Math. Surveys 49(5): 19—49. N. N. Bogoliubov and N. M. Krylov (1939). Fokker–Planck equations generated in perturbation theory by a method based on the spectral properties of a perturbed Hamiltonian.
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The more robust association between TCAs and affective switches, as opposed to more selective drugs, has been interpreted as indicating that more extensive perturbation in monoamine systems is associated with more frequent mood switching.
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For example, the discussions of Hermitian and unitary matrices were omitted because they are more relevant to quantum mechanics rather than classical mechanics, while those of Routh's procedure and time-independent perturbation theory were reduced.
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The mode volume directly impact the physics of the interaction of light and electrons with optical resonance, e.g. the local density of electromagnetic states, Purcell effect, cavity perturbation theory, strong interaction with quantum emitters, superradiance.
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Furthermore, the meteorites cause a perturbation of local winds by turbulence, which is noticeable on Doppler outputs, and are falling nearly vertically so their resting place on the ground is close to their radar signature.
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While tidal forces from the primary are common on satellites, most satellite systems remain stable. Perturbation between satellites can occur, particularly in the early formation, as the gravity of satellites affect each other, and can result in ejection from the system or collisions between satellites or with the primary. Simulations show that such interactions cause the orbits of the inner moons of the Uranus system to be chaotic and possibly unstable. Some of Io's active can be explained by perturbation from Europa's gravity as their orbits resonate.
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For some differential equations, application of standard methods—such as the Euler method, explicit Runge–Kutta methods, or multistep methods (for example, Adams–Bashforth methods)—exhibit instability in the solutions, though other methods may produce stable solutions. This "difficult behaviour" in the equation (which may not necessarily be complex itself) is described as stiffness, and is often caused by the presence of different time scales in the underlying problem.Miranker, A. (2001). Numerical Methods for Stiff Equations and Singular Perturbation Problems: and singular perturbation problems (Vol. 5).
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Jan Raphael Høegh-Krohn (10 February 1938 – 24 January 1988) was a Norwegian mathematician. He finished his Ph.D. in 1966 entitled On Partly Gentle Perturbation with Application to Perturbation by Annihilation-Creation Operator under the supervision of Kurt Friedrichs at the New York University. He has authored over 150 papers and is known for the discovery of a fundamental duality in relativistic quantum statistical mechanics by representing the basic correlation functions in terms of a certain stochastic process, now known as the Høegh-Krohn process.
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An even more convincing calculation is the derivation of Regge trajectories (and hence eigenvalues) of the radial Schrödinger equation with Yukawa potential by both a perturbation method (with the old \ell(\ell+1) factor) and independently the derivation by the WKB method (with Langer replacement)-- in both cases even to higher orders. For the perturbation calculation see Müller-Kirsten bookHarald J.W. Müller- Kirsten, Introduction to Quantum Mechanics: Schrödinger Equation and Path Integral, 2nd ed., World Scientific (Singapore, 2012), Chapter 16. and for the WKB calculation Boukema.
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This leads to a limitation of each phase being completed within a reset before another perturbation can be received. The main difference between the two assumptions is for pulsatile the effects of any inputs must be known or measured prior. In weak coupling, only the magnitude of response due to a perturbation needs to be measured to calculate phase resetting. The weak coupling also induces the claim that many cycles must occur prior to convergence of oscillators to phase lock to lead to synchronization.
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The envelope is approximately the integral of the perturbation. The perturbation to envelope transfer function rolls off at 6 dB/octave and causes −90° of phase shift. The light bulb has thermal inertia so that its power to resistance transfer function exhibits a single pole low pass filter. The envelope transfer function and the bulb transfer function are effectively in cascade, so that the control loop has effectively a low pass pole and a pole at zero and a net phase shift of almost −180°.
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The community perspective requires the existence of alternative stable states (i.e., more than one valley) before the perturbation, since the landscape is not changing. Because communities have some level of resistance to change, they will stay in their domain of attraction (or stable state) until the perturbation is large enough to force the system into another state. In the ball-and-cup model, this would be the energy required to push the ball up and over a hill, where it would fall downhill into a different valley.
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Viscosity only acts to decrease how rapidly a given perturbation will grow or decay with time. Examples of when this case would apply are when almost any liquid undergoes thread/jet breakup in an air environment.
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The predominant part of the radio emission in the Hydra Cluster comes from NGC 3309. The radio emission in NGC 3309 may have been triggered by a resent perturbation with the giant spiral galaxy NGC 3312.
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It has about half the mass of the Sun. The orbit of this star causes perturbation effects on the orbit of the AB pair, resulting in periodic changes in their orbital eccentricity and other orbital elements.
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337 All preambles contain the following phrase: Damen comments that here the treason definition from the treason statutes of the States of Holland and the States General of the late 1580s and early 1590s is extended from "perturbation of the public order" to "perturbation of the stance of the religion" and hence of the Church. In other words, the court could have convicted the defendants for "perturbing public order" as a consequence of "sustaining pernicious maxims" (the Remonstrant theses that had at the time recently been condemned as "heretical" by the Synod of Dort), but instead the court opted for declaring the "perturbation" of the Church as itself "treasonous." This amounted to "legislating from the bench" as this was an entirely new element of the Dutch law of treason as it existed since the 1590s.Damen, p.
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Singularly perturbed problems are generally characterized by dynamics operating on multiple scales. Several classes of singular perturbations are outlined below. The term "singular perturbation" was coined in the 1940s by Kurt Otto Friedrichs and Wolfgang R. Wasow.
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Each of the examples described below shows how a naive perturbation analysis, which assumes that the problem is regular instead of singular, will fail. Some show how the problem may be solved by more sophisticated singular methods.
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Kerr–Schild perturbations are a special type of perturbation to a spacetime metric which only appear linearly in the Einstein field equations which describe general relativity. They were found by Roy Kerr and Alfred Schild in 1965.
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Pyrrhonism was founded by Pyrrho (c. 360 – c. 270 BCE), and was the first Western school of philosophical skepticism. The goal of Pyrrhonist practice is to attain the state of ataraxia (ataraxia, Greek: ἀταραξία) – freedom from perturbation.
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The Davis–Kahan–Weinberger dilation theoremChandler Davis, W. M. Kahan, and H. F. Weinberger Norm-Preserving Dilations and Their Applications to Optimal Error Bounds, SIAM J. Numer. Anal. 19-3 (1982), pp. 445–469. is one of the landmark results in the dilation theory of Hilbert space operators and has found applications in many different areas. A PhD thesis titled "Backward Perturbation and Sensitivity Analysis of Structured Polynomial Eigenvalue Problem" B. Adhikari, Backward Perturbation and Sensitivity Analysis of Structured Polynomial Eigenvalue Problems, Ph.D. thesis, Department of Mathematics, IIT Guwahati, Guwahati, India, 2008.
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There are limits to the validity of the virtual particle picture. The virtual-particle formulation is derived from a method known as perturbation theory which is an approximation assuming interactions are not too strong, and was intended for scattering problems, not bound states such as atoms. For the strong force binding quarks into nucleons at low energies, perturbation theory has never been shown to yield results in accord with experiments, thus, the validity of the "force-mediating particle" picture is questionable. Similarly, for bound states the method fails.
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The gauge-invariant perturbation theory is based on developments by Bardeen (1980), Kodama and Sasaki (1984) building on the work of Lifshitz (1946).Lifshitz E M (1946) J. Phys. (USSR), 10, 116 This is the standard approach to perturbation theory of general relativity for cosmology. This approach is widely used for the computation of anisotropies in the cosmic microwave background radiation as part of the physical cosmology program and focuses on predictions arising from linearisations that preserve gauge invariance with respect to Friedmann-Lemaître-Robertson-Walker (FLRW) models.
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To ensure non-reflectivity, a radiative condition is used for the hydrostatic part of the mesoscale pressure perturbation p_h at that boundary. Hence, vertically propagating internal gravity waves are allowed to leave the computational domain (Klemp and Durran 1983). For the nonhydrostatic part of the mesoscale pressure perturbation, homogeneous staggered Dirichlet conditions are imposed. Being justified by the fact that nonhydrostatic effects are negligible at large heights, this condition is necessary, if singularity of the elliptic pressure equation is to be avoided in view of the Neumann boundary conditions at all other boundaries.
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Two dimensional correlation analysis is a mathematical technique that is used to study changes in measured signals. As mostly spectroscopic signals are discussed, sometime also two dimensional correlation spectroscopy is used and refers to the same technique. In 2D correlation analysis, a sample is subjected to an external perturbation while all other parameters of the system are kept at the same value. This perturbation can be a systematic and controlled change in temperature, pressure, pH, chemical composition of the system, or even time after a catalyst was added to a chemical mixture.
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Numerous research has suggested two primary assumptions that allow the use of PRCs to be used to predict the occurrence of synchrony within neural oscillation. These assumptions work to show synchrony within coupled neurons that are linked to other neurons. The first assumption claims that coupling between neurons must be weak and requires an infinitesimally small phase change in response to a perturbation. The second assumption assumes coupling between neurons to be pulsatile where the perturbation to calculate PRC should only include those inputs that are received within the circuit.
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An alternative way of dealing with jump matrices with no analytic extensions was introduced in . Another extension of the theory appears in where the underlying space of the Riemann–Hilbert problem is a compact hyperelliptic Riemann surface. The right factorization problem is no more holomorphic, but rather meromorphic, by reason of the Riemann–Roch theorem. The Riemann–Hilbert problem deformation theory is applied to the problem of stability of the infinite periodic Toda lattice under a "short range" perturbation (for example a perturbation of a finite number of particles).
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If a transformation to quasi-orthogonal coordinates is applied to Maxwell's equations in order to conceal a perturbation on a flat conducting plane rather than a singular point, as in the first demonstration of a transformation optics-based cloak, then an object can be hidden underneath the perturbation. This is sometimes referred to as a "carpet" cloak. As noted above, the original cloak demonstrated utilized resonant metamaterial elements to meet the effective material constraints. Utilizing a quasi-conformal transformation in this case, rather than the non- conformal original transformation, changed the required material properties.
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A sublinear modulus of continuity can easily be found for any uniformly function which is a bounded perturbation of a Lipschitz function: if f is a uniformly continuous function with modulus of continuity ω, and g is a k Lipschitz function with uniform distance r from f, then f admits the sublinear module of continuity min{ω(t), 2r+kt}. Conversely, at least for real-valued functions, any special uniformly continuous function is a bounded, uniformly continuous perturbation of some Lipschitz function; indeed more is true as shown below (Lipschitz approximation).
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For some perturbation wavelengths, the effect of the second radius of curvature can overcome the pressure effect of the first radius of curvature, inducing a larger pressure in the thickened regions than the thinned regions. This would push fluid back toward the thinned regions and tend to return the thread to its original, undisturbed shape. However, for other perturbation wavelengths, the capillary pressure induced by the second radius of curvature will reinforce that of the first radius of curvature. This will drive fluid from the thinned to the thickened regions and further promote thread breakup.
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As it eliminates the effects of inertia and the need for a velocity scale, it is oftentimes more convenient to express scaling relationships in terms of the Ohnesorge number rather than the Reynolds and Weber number individually. The perturbation wavelength is the characteristic length of the disturbance on the surface of the jet, assuming that any arbitrary disturbance can be decomposed via a Fourier transform into its constitutive components. The wavelength of the perturbation is critical in determining if a particular disturbance will grow or decay in time.
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The main mathematical tools to study critical points are renormalization group, which takes advantage of the Russian dolls picture or the self-similarity to explain universality and predict numerically the critical exponents, and variational perturbation theory, which converts divergent perturbation expansions into convergent strong-coupling expansions relevant to critical phenomena. In two- dimensional systems, conformal field theory is a powerful tool which has discovered many new properties of 2D critical systems, employing the fact that scale invariance, along with a few other requisites, leads to an infinite symmetry group.
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He began this research in 1976 in connection with experimental studies carried out at AMOLF by the group of Marnix van der Wiel. Initially, his interest was focused on multi-photon transitions treated by non-perturbation quantum theory. However, he switched to perturbation methods in quantum theory when it became possible experimentally to attain ultra-high laser intensities at very high frequencies based on the High-Intensity High-Frequency Floquet Theory (HI- HFFT).M. Gavrilă and J.Z. Kamiński: Free-Free Transitions in Intense, High- Frequency Laser Fields, Physical Review Letters, 52 (8), 613–616 (1984).
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Beta Pictoris b is a super-Jupiter, an exoplanet that has a radius and mass greater than that of the planet Jupiter. It has a temperature of , most likely due to its dusty atmosphere and mass (normally it would be much colder). It has a mass of between 9 and 13 Jupiter masses (), and a radius of 1.46 . In 2018, a study directly measured the astrometric perturbation of Beta Pictoris by Beta Pictoris b, one of the first examples of an exoplanet being measured directly by its astrometric perturbation.
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This result can be obtained by assuming that the coupling constant g is small (so small nonlinearities), as for high energies, and applying perturbation theory. The relevance of this result is due to the fact that a Yang–Mills theory that describes strong interaction and asymptotic freedom permits proper treatment of experimental results coming from deep inelastic scattering. To obtain the behavior of the Yang–Mills theory at high energies, and so to prove asymptotic freedom, one applies perturbation theory assuming a small coupling. This is verified a posteriori in the ultraviolet limit.
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In the 1968 science-fiction film The Green Slime, an orbital perturbation propels the asteroid Flora into a collision course with Earth. Size comparison: the first 10 asteroids profiled against Earth's Moon. Flora is third from the right.
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The nonlinearity of the Einstein field equations often leads one to consider approximation methods in solving them. For example, an important approach is to linearise the field equations. Techniques from perturbation theory find ample application in such areas.
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Early Pliensbachian (Early Jurassic) C-isotope perturbation and the diffusion of the Lithiotis Fauna: Insights from the western Tethys. Palaeogeography, Palaeoclimatology, Palaeoecology, 410, 255–263. doi:10.1016/j.palaeo.2014.05.025 Fossil prosauropod tracks have been reported from the formation.
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Biochemical and Biophysical Research Communications (1969), 35(4), 492-8.McDonald, Charles C.; Phillips, William Dale. Perturbation of the PMR [proton magnetic resonance] spectrum of lysozyme by cobaltous ions. Biochemical and Biophysical Research Communications (1969), 35(1), 43-51.
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Instead of mapping a texture onto an object to simulate roughness, Blinn proposed a method of calculating the degree of lighting a point on a surface should receive based on an established "perturbation" of the normals across the surface.
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Accurate anharmonic vibrational energies can then be obtained by solving the anharmonic vibrational equations for the atoms within a mean-field theory. Finally, it is possible to use Møller–Plesset perturbation theory to go beyond the mean-field formalism.
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C. B. Peel, B. M. Hochwald, and A. L. Swindlehurst, A vector-perturbation technique for near-capacity multiantenna multi-user communication - Part I: channel inversion and regularization, IEEE Transactions on Communications, vol. 53, no. 1, pp. 195–202, 2005.
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He was department chair 1970–72. He retired in 1980. Wolfgang Wasow's main research area was singular perturbation theory. A classical application is the thin boundary layer that forms on a solid surface as a fluid flows over it.
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This approach is based on asymptotic freedom, which allows perturbation theory to be used accurately in experiments performed at very high energies. Although limited in scope, this approach has resulted in the most precise tests of QCD to date.
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Perturbation theory comprises mathematical methods that are used to find an approximate solution to a problem which cannot be solved exactly. (It is closely related to methods used in numerical analysis, which are ancient.) The earliest use of modern perturbation theory was to deal with the otherwise unsolvable mathematical problems of celestial mechanics: Newton's solution for the orbit of the Moon, which moves noticeably differently from a simple Keplerian ellipse because of the competing gravitation of the Earth and the Sun. Perturbation methods start with a simplified form of the original problem, which is carefully chosen to be exactly solvable. In celestial mechanics, this is usually a Keplerian ellipse, which is correct when there are only two gravitating bodies (say, the Earth and the Moon), or a circular orbit, which is only correct in special cases of two-body motion, but is often close enough for practical use.
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Image generated using Kalles Fraktaler 2+ Kalles Fraktaler is a free Windows- based fractal zoom computer program used for zooming into fractals such as the Mandelbrot set and the Burning Ship fractal at very high speed, utilizing Perturbation and Series Approximation.
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In 2011, she became a fellow of the Society for Industrial and Applied Mathematics "for contributions to numerical linear algebra, perturbation theory, and applications.". She was elected as a fellow of the American Association for the Advancement of Science in 2018.
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"Tree lizard (Urosaurus ornatus) territories: experimental perturbation of the sex ratio". Ecology 68 (6): 2059-2062. Females also can vary in throat coloration, although this is not as well-studied. When gravid with eggs, females tend to be orange or red.
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By way of comparison, the Sun has an azimuthal velocity along its equator of just . Based upon analysis of data collected during the Hipparcos mission, this star may have a proper motion companion that is causing gravitational perturbation of Gamma Gruis.
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Poster, 11th annual meeting of the Organization of Human Brain Mapping (Toronto, Canada) This is comparable to the strong influence of visual feedback on reaching movements during visual perturbation (e.g. shifting the location of objects by viewing through a prism).
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The researchers concluded that the extinction of Cit− had been due to some unknown "rare environmental perturbation", similar to that which can impact natural populations. The final replicate was integrated into the main LTEE experiment, becoming the thirteenth population, Ara-7.
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Analytically predicting how the perturbation changes the optical response is a classical problem in electromagnetics, with important implications spanning from the radio-frequency domain to present-day nano-optics. The underlying assumption of cavity perturbation theory is that electromagnetic fields inside the cavity after the change differ by a very small amount from the fields before the change. Then Maxwell's equations for original and perturbed cavities can be used to derive analytical expressions for the resulting resonant frequency shift and linewidth change (or Q factor change) by referring only to the original unperturbed mode (not the perturbed one).
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Muscles possess nonlinear visco-elastic properties when they contract. This property can autocorrect movements when a muscle is forced to change its length, and at a velocity different from that with which it was originally commanded. Such automatic correction is useful when a commanded action is perturbated, for example, if a step goes into a hole as this causes the foot to unexpectedly stretch down. The nonlinear visco-elastic properties of muscles interact with these perturbation induced velocity and length differences such that they counteract directly, as they happen, the effects upon the body of the perturbation.
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The reverse is true at b, where the perturbation retards the orbital motion of Uranus. John Couch Adams learned of the irregularities while still an undergraduate and became convinced of the "perturbation" hypothesis. Adams believed, in the face of anything that had been attempted before, that he could use the observed data on Uranus, and utilising nothing more than Newton's law of gravitation, deduce the mass, position and orbit of the perturbing body. After his final examinations in 1843, Adams was elected fellow of his college and spent the summer vacation in Cornwall calculating the first of six iterations.
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The earliest use of what would now be called perturbation theory was to deal with the otherwise unsolvable mathematical problems of celestial mechanics: for example the orbit of the Moon, which moves noticeably differently from a simple Keplerian ellipse because of the competing gravitation of the Earth and the Sun.Martin C. Gutzwiller, "Moon-Earth-Sun: The oldest three-body problem", Rev. Mod. Phys. 70, 589 – Published 1 April 1998 Perturbation methods start with a simplified form of the original problem, which is simple enough to be solved exactly. In celestial mechanics, this is usually a Keplerian ellipse.
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Using perturbation theory, the total effect of a small interaction term can be approximated order by order by a series expansion in the number of virtual particles participating in the interaction. Every term in the expansion may be understood as one possible way for (physical) particles to interact with each other via virtual particles, expressed visually using a Feynman diagram. The electromagnetic force between two electrons in QED is represented (to first order in perturbation theory) by the propagation of a virtual photon. In a similar manner, the W and Z bosons carry the weak interaction, while gluons carry the strong interaction.
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This is a case of quantum triviality, which means that quantum corrections completely suppress the interactions in the absence of a cut-off. Since the Landau pole is normally identified through perturbative one-loop or two-loop calculations, it is possible that the pole is merely a sign that the perturbative approximation breaks down at strong coupling. Perturbation theory may also be invalid if non-adiabatic states exist. Lattice gauge theory provides a means to address questions in quantum field theory beyond the realm of perturbation theory, and thus has been used to attempt to resolve this question.
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As a floating object rises or falls, the forces external to it change and, as all objects are compressible to some extent or another, so does the object's volume. Buoyancy depends on volume and so an object's buoyancy reduces if it is compressed and increases if it expands. If an object at equilibrium has a compressibility less than that of the surrounding fluid, the object's equilibrium is stable and it remains at rest. If, however, its compressibility is greater, its equilibrium is then unstable, and it rises and expands on the slightest upward perturbation, or falls and compresses on the slightest downward perturbation.
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The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos. Page 166. His other work includes contributions in the physics of the early universe, cosmological perturbation theory, and cosmic 21-cm fluctuations.Publications. Kris Sigurdson at the University of British Columbia.
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The actual masses of these mesons are obtained in chiral perturbation theory through an expansion in the (small) actual masses of the quarks. In other phases of quark matter the full chiral flavour symmetry may be recovered, or broken in completely different ways.
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While the form of the perturbation may appear very restrictive, there are several black hole metrics which can be written in Kerr–Schild form, such as Schwarzschild (stationary black hole), Kerr (rotating), Reissner–Nordström (charged) and Kerr–Newman (both charged and rotating).
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The precise form of the primitive equations depends on the vertical coordinate system chosen, such as pressure coordinates, log pressure coordinates, or sigma coordinates. Furthermore, the velocity, temperature, and geopotential variables may be decomposed into mean and perturbation components using Reynolds decomposition.
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Arguments for this hypothesis consider that mental dysfunction can be explained by slight perturbation of the network model's processing. This emerging line of research incorporates a wide range of theories and models, and TRACE represents just one piece of a growing puzzle.
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Causal perturbation theory is a mathematically rigorous approach to renormalization theory, which makes it possible to put the theoretical setup of perturbative quantum field theory on a sound mathematical basis. It goes back to a seminal work by Henri Epstein and Vladimir Jurko Glaser.
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Rhinella ruizi occurs in high- Andean interior forests at elevations of above sea level. Development is probably direct (i.e., there is no free-living larval stage). It is a common species within its range and it may tolerate a low degree of habitat perturbation.
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Perturbation theory, which deals with small perturbations from e.g. a homogeneous metric, only holds as long as the perturbations are not too large, and N-body simulations use Newtonian gravity which is only a good approximation when speeds are low and gravitational fields are weak.
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Correlated calculations scale less favorably, though their accuracy is usually greater, which is the trade off one needs to consider. One popular method is Møller-Plesset perturbation theory (MP). To second order (MP2), MP scales as N4. To third order (MP3) MP scales as N6.
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Petar V. Kokotovic (Serbian Cyrillic: Петар В. Кокотовић) is professor emeritus in the College of Engineering at the University of California, Santa Barbara, USA. He has made contributions in the areas of adaptive control, singular perturbation techniques, and nonlinear control especially the backstepping stabilization method.
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The ghost term in the Lagrangian represents the functional determinant of the Jacobian of this embedding, and the properties of the ghost field are dictated by the exponent desired on the determinant in order to correct the functional measure on the remaining "physical" perturbation axes.
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In mathematics and physics, multiple-scale analysis (also called the method of multiple scales) comprises techniques used to construct uniformly valid approximations to the solutions of perturbation problems, both for small as well as large values of the independent variables. This is done by introducing fast-scale and slow-scale variables for an independent variable, and subsequently treating these variables, fast and slow, as if they are independent. In the solution process of the perturbation problem thereafter, the resulting additional freedom – introduced by the new independent variables – is used to remove (unwanted) secular terms. The latter puts constraints on the approximate solution, which are called solvability conditions.
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Cavity material perturbation When a material within a cavity is changed (permittivity and/or permeability), a corresponding change in resonant frequency can be approximated as:David Pozar, Microwave Engineering, 2nd edition, Wiley, New York, NY, 1998. where \omega is the angular resonant frequency of the perturbed cavity, \omega_0 is the resonant frequency of the original cavity, E_0 and H_0 represent original electric and magnetic field respectively, \mu and \epsilon are original permeability and permittivity respectively, while \Delta\mu and \Delta\epsilon are changes in original permeability and permittivity introduced by material change. Expression () can be rewritten in terms of stored energies as:Mathew, K. T. 2005. Perturbation Theory.
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Microwave measurement techniques based on cavity perturbation theory are generally used to determine the dielectric and magnetic parameters of materials and various circuit components such as dielectric resonators. Since ex-ante knowledge of the resonant frequency, resonant frequency shift and electromagnetic fields is necessary in order to extrapolate material properties, these measurement techniques generally make use of standard resonant cavities where resonant frequencies and electromagnetic fields are well known. Two examples of such standard resonant cavities are rectangular and circular waveguide cavities and coaxial cables resonators . Cavity perturbation measurement techniques for material characterization are used in many fields ranging from physics and material science to medicine and biology.
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According to this criterion a deterministic trajectory will begin to move between two nonlinear resonances in a chaotic and unpredictable manner, in the parameter range : K \approx S^2 = (\Delta \omega_r/\Delta_d)^2 > 1 . Here K is the perturbation parameter, while S = \Delta \omega_r/\Delta_d is the resonance-overlap parameter, given by the ratio of the unperturbed resonance width in frequency \Delta \omega_r (often computed in the pendulum approximation and proportional to the square-root of perturbation), and the frequency difference \Delta_d between two unperturbed resonances. Since its introduction, the Chirikov criterion has become an important analytical tool for the determination of the chaos border.
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The idea of location perturbation is to replace the exact location information with a coarser grained spatial range, and thus uncertainty would be introduced when the adversaries try to match the user to either a known location identity or external observation of location identity. Location perturbation is usually satisfied by using spatial cloaking, temporal cloaking, or location obfuscation. Spatial and temporal cloaking refers to the wrong or imprecise location and time reported to the service providers, instead of the exact information. For example, location privacy could be enhanced by increasing the time between location reports, since higher report frequencies makes reidentification more possible to happen through data mining.
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Interest in the relationship between psychiatric syndromes or symptoms and immune function has been a consistent theme since the beginning of modern medicine. Claude Bernard, the father of modern physiology, with his pupils Claude Bernard, a French physiologist of the Muséum national d'Histoire naturelle (National Museum of Natural History in English), formulated the concept of the milieu interieur in the mid-1800s. In 1865, Bernard described the perturbation of this internal state: "... there are protective functions of organic elements holding living materials in reserve and maintaining without interruption humidity, heat and other conditions indispensable to vital activity. Sickness and death are only a dislocation or perturbation of that mechanism" (Bernard, 1865).
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Perturbation theory was first devised to solve otherwise intractable problems in the calculation of the motions of planets in the solar system. For instance, Newton's law of universal gravitation explained the gravitation between two astronomical bodies, but when a third body is added, the problem was, "How does each body pull on each?" Newton's equation only allowed the mass of two bodies to be analyzed. The gradually increasing accuracy of astronomical observations led to incremental demands in the accuracy of solutions to Newton's gravitational equations, which led several notable 18th and 19th century mathematicians, such as Lagrange and Laplace, to extend and generalize the methods of perturbation theory.
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He also promoted the concept of size extensivity for many-body theory that scales properly with the number of particles, now viewed as an essential element of sound quantum chemistry approximations. Bartlett was also the first to explore the combination of coupled-cluster and many-body perturbation theories (in 1985) and proposed vastly successful approximations. It is now widely agreed that the coupled cluster and many-body perturbation methods that Bartlett has been instrumental in establishing offer the most predictive, generally applicable approaches in the field. These methods helped electronic structure theory be accepted by the chemistry community as a reliable and integral branch of chemistry.
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The theory must be characterized by a choice of finitely many parameters, which could, in principle, be set by experiment. For example, in quantum electrodynamics these parameters are the charge and mass of the electron, as measured at a particular energy scale. On the other hand, in quantizing gravity there are, in perturbation theory, infinitely many independent parameters (counterterm coefficients) needed to define the theory. For a given choice of those parameters, one could make sense of the theory, but since it is impossible to conduct infinite experiments to fix the values of every parameter, it has been argued that one does not, in perturbation theory, have a meaningful physical theory.
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Feynman was also interested in the relationship between physics and computation. He was also one of the first scientists to conceive the possibility of quantum computers. In the 1980s he began to spend his summers working at Thinking Machines Corporation, helping to build some of the first parallel supercomputers and considering the construction of quantum computers. In 1984–1986, he developed a variational method for the approximate calculation of path integrals, which has led to a powerful method of converting divergent perturbation expansions into convergent strong-coupling expansions (variational perturbation theory) and, as a consequence, to the most accurate determination of critical exponents measured in satellite experiments.
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Perturb-seq (also known as CRISP-seq and CROP-seq) refers to a high-throughput method of performing single cell RNA sequencing (scRNA-seq) on pooled genetic perturbation screens. Perturb-seq combines multiplexed CRISPR mediated gene inactivations with single cell RNA sequencing to assess comprehensive gene expression phenotypes for each perturbation. Inferring a gene’s function by applying genetic perturbations to knock down or knock out a gene and studying the resulting phenotype is known as reverse genetics. Perturb-seq is a reverse genetics approach that allows for the investigation of phenotypes at the level of the transcriptome, to elucidate gene functions in many cells, in a massively parallel fashion.
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In the relativistic theory, we have seen that the assumption that > the field description is correct in arbitrarily small space-time intervals > has led—in perturbation theory—to divergent expressions for the electron > self-energy and the bare charge. Renormalization theory has sidestepped > these divergence difficulties, which may be indicative of the failure of the > perturbation expansion. However, it is widely felt that the divergences are > symptomatic of a chronic disorder in the small-distance behaviour of the > theory. We might then ask why local field theories, that is, theories of > fields which can be described by differential laws of wave propagation, have > been so extensively used and accepted.
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The video of an experiment showing vacuum fluctuations (in the red ring) amplified by spontaneous parametric down-conversion. If the quantum field theory can be accurately described through perturbation theory, then the properties of the vacuum are analogous to the properties of the ground state of a quantum mechanical harmonic oscillator, or more accurately, the ground state of a measurement problem. In this case the vacuum expectation value (VEV) of any field operator vanishes. For quantum field theories in which perturbation theory breaks down at low energies (for example, Quantum chromodynamics or the BCS theory of superconductivity) field operators may have non-vanishing vacuum expectation values called condensates.
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In a quantum fluid, the situation is very complicated as one needs to deal with quantum operators, and matrix elements of such operators, which appear in various perturbation methods based on Feynman diagrams. The CHNC method provides an approximate "escape" from these difficulties, and applies to regimes beyond perturbation theory. In Robert B. Laughlin's famous Nobel Laureate work on the fractional quantum Hall effect, an HNC equation was used within a classical plasma analogy. In the CHNC method, the pair- distributions of the interacting particles are calculated using a mapping which ensures that the quantum mechanically correct non-interacting pair distribution function is recovered when the Coulomb interactions are switched off.
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Plutinos are a class of Kuiper belt object that display a similar bicoloured nature, and there are suggestions that not all plutinos' orbits are as stable as initially thought, due to perturbation by Pluto. Further developments are expected with more physical data on Kuiper belt objects.
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The theory is gauge invariant and it is finite to all orders of perturbation theory. For the standard model it can solve the Higgs boson mass hierarchy naturalness problem.J. W. Moffat, Beyond The Standard Model; arxiv:hep-ph/9802228 It also leads to a finite quantum gravity theory.
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Stable limit cycles are examples of attractors. They imply self-sustained oscillations: the closed trajectory describes the perfect periodic behavior of the system, and any small perturbation from this closed trajectory causes the system to return to it, making the system stick to the limit cycle.
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As an academic teacher, he offers semestral courses in general and quantum chemistry. Some of them are available online via the OpenCourseWare platform. In fall 2017, he taught "Perturbation theory for linear operator", using the book titled the same as the course by mathematician Tosio Kato.
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One proposed solution is a model that would estimate how difficult it would be for outside sources to get their hands on someone's private information. There are several mechanisms proposed that would be helpful in hiding data including location obfuscation, perturbation, confusion and suppression, and cryptographic techniques.
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The promising approach of preserving location privacy is to report data on users' behavior and at the same time protect identity and location privacy. Several methods have been investigated to enhance the performances of location-preserving techniques, such as location perturbation and the report of landmark objects.
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Soc, 47, 1-2. The muddy bank nests of cliff swallows are also vulnerable to barred owls, while other swallow species are known to be opportunistically taken.Hamilton, G. D., & Martin, R. F. (1985). Investigator perturbation and reproduction of the Cliff Swallow. The Auk, 102(1), 167-170.
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BAX, a molecule that is translocated to the mitochondria to release cytochrome C, initiates the cellular pathway of apoptosis. TUDCA prevents BAX from being transported to the mitochondria. This protects the mitochondria from perturbation and the activation of caspases. TUDCA also acts as a chemical chaperone.
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Thirdly, if one is studying an object which varies in a family, as is common in algebraic geometry and differential geometry, one may ask if the property is unchanged under perturbation (for example, if an object is constant on families or invariant under change of metric).
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In the 1980s and 1990s, full CI programs were adapted to provide arbitrary-order Møller-Plesset perturbation theory wave functions, and in the 2000s they have been adapted to provide coupled cluster wave functions to arbitrary orders, greatly simplifying the task of programming these complex methods.
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An orbital perturbation is when a force or impulse which is much smaller than the overall force or average impulse of the main gravitating body and which is external to the two orbiting bodies causes an acceleration, which changes the parameters of the orbit over time.
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As well as Feynman diagrams and perturbation theory, other techniques such as dispersion relations and the finite temperature analog of Cutkosky rules can also be used in the real time formulation. An alternative approach which is of interest to mathematical physics is to work with KMS states.
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72, 411 (1977) [Sov.Phys. JETP 45, 216 (1977)]. One may now try to interpolate the known coefficients with their large order behavior, and to then sum the perturbation series. The first attempts of reconstruction of the function by this method bear on the triviality of the theory.
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The same instrument recorded a crotchet, an instantaneous perturbation of the Earth's ionosphere by ionizing soft X-rays. This could not easily be understood at the time because it predated the discovery of X-rays (by Roentgen) and the recognition of the ionosphere (by Kennelly and Heaviside).
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Bousinesq approximation is to ignore the density change due to pressure perturbation and keep the density change due to temperature change. This is a fairly good approximation in the CBL. The latter two approximations are not always effective in the real CBL. But this is acceptable in theoretical research.
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Cell Biol.7, 211-224 (2006). The future of cell culturing for fundamental studies and biomedical applications lies in the creation of multicellular structure and organization in three-dimensions.Birgersdotter, A., Sandberg, R. & Ernberg, I. Gene expression perturbation in vitro--a growing case for three-dimensional (3D) culture systems. Semin.
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In condensed matter physics, relaxation is usually studied as a linear response to a small external perturbation. Since the underlying microscopic processes are active even in the absence of external perturbations, one can also study "relaxation in equilibrium" instead of the usual "relaxation into equilibrium" (see fluctuation-dissipation theorem).
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In the Quantum Chemistry Speed Test , Firefly's DFT code came second (losing only to commercial QChem), beating other free DFT codes by a large margin. Firefly's unique capabilities include XMCQDPT2, a reformulation of Nakano's multi-state multi-configuration quasi-degenerate perturbation theory (MCQDPT) correcting for some of its deficiencies.
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The tsunami affected the coasts of Peru and northern Chile and was observed across the Pacific Ocean, in Australia, New Zealand, Samoa, Tonga, Fiji, Hawaii, Mexico, California and Japan.An oceanic perturbation, Otago Daily Times, Issue 4753, 12 May 1877, Page 2 At Arica eight separate large waves were recorded.
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Brown contends that the dualistic nature and rituals surrounding openings to ukhu pacha may have made it easier to initially get indigenous laborers to work in the mines. However, at the same time, because mining was considered a perturbation of "subterranean life and the spirits that ruled it; they yielded to sacredness that did not belong to the familiar universe, a deeper and riskier sacredness." In order to insure that the perturbation did not cause evil in the miners or the world, indigenous populations made traditional offering to the supay. However, Catholic missionaries preached that the supay were purely evil and equated them with the devil and hell and thus prohibited offerings.
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An example would be GaAs-AlAs, constructing it from a virtual crystal of Al0.5Ga0.5As, then introducing an interface. After this a perturbation is added to turn the crystal into pure GaAs, whilst on the other side, the perturbation transforms the crystal in pure AlAs. These perturbations are sufficiently small so that they can be handled by linear- response theory and the electrostatic potential lineup across the interface can then be obtained up to the first order from the charge density response to those localized perturbations. Linear response theory works well for semiconductors with similar potentials (such as GaAs-AlAs) as well as dissimilar potentials (such as GaAs-Ge), which was doubted at first.
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A perturbed problem whose solution can be approximated on the whole problem domain, whether space or time, by a single asymptotic expansion has a regular perturbation. Most often in applications, an acceptable approximation to a regularly perturbed problem is found by simply replacing the small parameter \varepsilon by zero everywhere in the problem statement. This corresponds to taking only the first term of the expansion, yielding an approximation that converges, perhaps slowly, to the true solution as \varepsilon decreases. The solution to a singularly perturbed problem cannot be approximated in this way: As seen in the examples below, a singular perturbation generally occurs when a problem's small parameter multiplies its highest operator.
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In quantum field theory, a Ward–Takahashi identity is an identity between correlation functions that follows from the global or gauge symmetries of the theory, and which remains valid after renormalization. The Ward–Takahashi identity of quantum electrodynamics was originally used by John Clive Ward and Yasushi Takahashi to relate the wave function renormalization of the electron to its vertex renormalization factor, guaranteeing the cancellation of the ultraviolet divergence to all orders of perturbation theory. Later uses include the extension of the proof of Goldstone's theorem to all orders of perturbation theory. More generally, a Ward–Takahashi identity is the quantum version of classical current conservation associated to a continuous symmetry by Noether's theorem.
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Unfortunately, there are many ROHF based MP2-like methods because of arbitrariness in the ROHF wavefunction(for example HCPT, ROMP, RMP (also called ROHF-MBPT2), OPT1 and OPT2, ZAPT, IOPT, etc.). Some of the ROHF based MP2-like theories suffer from spin-contamination in their perturbed density and energies beyond second- order. These methods, Hartree–Fock, unrestricted Hartree–Fock and restricted Hartree–Fock use a single determinant wave function. Multi-configurational self-consistent field (MCSCF) methods use several determinants and can be used for the unperturbed operator, although not uniquely, so many methods, such as complete active space perturbation theory (CASPT2), and Multi-Configuration Quasi-Degenerate Perturbation Theory (MCQDPT), have been developed.
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This is because the strength of the planet's perturbation on the satellite's orbit is much stronger for orbits close to the planet, but drops below the strength of the Sun's perturbation for orbits farther away. Examples of satellites whose Laplace plane is close to their planet's equatorial plane include the satellites of Mars and the inner satellites of the giant planets. Examples of satellites whose Laplace plane is close to their planet's orbital plane include Earth's Moon and the outer satellites of the giant planets. Some satellites, such as Saturn's Iapetus, are situated in the transitional zone and have Laplace planes that are midway between their planet's equatorial plane and the plane of its solar orbit.
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We can imagine "disturbing" the gravitational field outside some isolated massive object by "sending in some radiation from infinity". We can ask: what happens as the incoming radiation interacts with the ambient field? In the approach of classical perturbation theory, we can start with Minkowski vacuum (or another very simple solution, such as the de Sitter lambdavacuum), introduce very small metric perturbations, and retain only terms up to some order in a suitable perturbation expansion—somewhat like evaluating a kind of Taylor series for the geometry of our spacetime. This approach is essentially the idea behind the post-Newtonian approximations used in constructing models of a gravitating system such as a binary pulsar.
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The fourth type of possible quartic potential is that of "asymmetric shape" of one of the first two named above. The double-well and other quartic potentials can be treated by a variety of methods—the main methods being (a) a perturbation method (that of B. Dingle and H.J.W. Müller-Kirsten in this reference the perturbation method is developed for the cosine potential, i.e. the Mathieu equation; see Mathieu function.) which requires the imposition of boundary conditions, (b) the WKB method and (c) the path integral method.. All cases are treated in detail in the book of H.J.W. Müller-Kirsten.Harald J.W. Müller- Kirsten, Introduction to Quantum Mechanics: Schrödinger Equation and Path Integral, 2nd ed.
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Finally, the October 2016 preprint and subsequent paper demonstrate the bioinformatic reconstruction of the T cell receptor signaling pathway in Jurkat cells based on CROP-seq data. While these publications used these protocols for answering complex biological questions, this technology can also be used as a validation assay to ensure the specificity of any CRISPR based knockdown or knockout; the expression levels of the target genes as well as others can be measured with single cell resolution in parallel, to detect whether the perturbation was successful and to assess the experiment for off target effects. Furthermore, these protocols make it possible to perform perturbation screens in heterogeneous tissues, while obtaining cell type specific gene expression responses.
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Her research focuses on theoretical spectroscopy and the development of first- principles methods for electronic excitations based on (time-dependent) density functional theory and many-body perturbation theory. She edited the book "First Principles Approaches to Spectroscopic Properties of Complex Materials". She is an associate editor of Npj Computational Materials.
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To obtain free-energies from the created ground state energy potential one needs to perform sampling. These can be obtained by applying a sampling method like molecular dynamics or Monte Carlo simulations at different states along the reaction coordinates. Typically this is done using a free energy perturbation / umbrella sampling approach.
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79–82, 14–16 May 1991Ogunlade, O.; Yifan Chen; Kosmas, P.; "Measurement of the complex permittivity of microbubbles using a cavity perturbation technique for contrast enhanced ultra-wideband breast cancer detection," Engineering in Medicine and Biology Society (EMBC), 2010 Annual International Conference of the IEEE, vol., no., pp.6733–6736, Aug.
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Vlada Gelman wrote for TVLine that Maslany's performance as Tony in "Variable and Full of Perturbation" was proof that "there [isn't] anything Tatiana Maslany can't do". Conversely, Rob Hunter of Film School Rejects felt that her portrayal of Tony provided "proof that Maslany is human after all and capable of failure".
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Orbital perturbation: changes in Asbolus semi-major axis during the next 5500 years. After the encounter with Jupiter in 2700 years, the orbit becomes unpredictable. Centaurs have short dynamical lifetimes due to perturbations by the giant planets. Asbolus is estimated to have an orbital half-life of about 860 kiloannum.
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The procedure consists in fix a number of values for the perturbation such that these values are significant for the instance: on average probability and not rare. After that, on runtime it will be possible to check the benchmark plot in order to get an average idea on the instances passed.
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This approach of determining stability from second variation is used now widely. Perturbation methods became very successful despite that nonlinear nature of capillary interaction can limit their application. Other methods now include direct simulation. To that moment most methods for stability determination required calculation of equilibrium as a basis for perturbations.
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However, unlike earlier SAFT equations of state that used unbonded spherical particles as a reference fluid, it uses spherical particles in the context of hard chains as reference fluid.Gross J, Sadowski G. Perturbed-chain SAFT: An equation of state based on a perturbation theory for chain molecules. Industrial & engineering chemistry research.
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Tuscaloosa: University of Alabama Press. 239. This snail is highly susceptible to a single catastrophic extinction event. As such, the species deserves immediate conservation attention. Artificial propagation and reintroduction of Leptoxis compacta into its native range may be a viable recovery strategy to prevent extinction from a single perturbation event.
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There were local Greek CatholicParish and permanent one-class school. A manuscript of the ancient Ukrainian drama "Povist' o zburenni pekla" (eng. The tale of the perturbation of hell) by Ivan Franko was found in the village. In 1899-1914 a public courtyard with a tavern was leased by the community.
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The state possesses no quanta at the asymptotic past infinity. The Bunch-Davies state is the zero-particle state as seen by a geodesic observer, that is, an observer who is in free fall in the expanding state. The state explains the origin of cosmological perturbation fluctuations in inflationary models.
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This method, also called Free energy perturbation (or FEP), involves sampling from state A only. It requires that all the high probability configurations of super state B are contained in high probability configurations of super state A, which is a much more stringent requirement than the overlap condition stated above.
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This includes use of gene perturbation techniques such as Morpholino knockdown and CRISPR-Cas9 mutagenesis, and methods for living imaging such as mRNA injection. The development of each technique opens doors for new avenues of inquiry and experimentation and expands the number and complexity of questions C. teleta researchers can thoroughly investigate.
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Similarly, in three-dimensional space a very small perturbation of any two parallel or intersecting lines will almost certainly turn them into skew lines. Therefore, any four points in general position always form skew lines. In this sense, skew lines are the "usual" case, and parallel or intersecting lines are special cases.
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Miranker's workWillard L. Miranker, 60 years, Computing 48:1-3, 1992 fulltext includes articles and books on stiff differential equations,Miranker, Willard L., Numerical Methods for Stiff Equations And Singular Perturbation Problems, D. Reidel Publishing Co., Dordrecht-Boston, Mass., 1981. interval arithmetic, analog computing, and neural networks and the modeling of consciousness.
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The criss-cross algorithm visits all 8 corners of the Klee–Minty cube in the worst case. It visits 3 additional corners on average. The Klee–Minty cube is a perturbation of the cube shown here. In mathematical optimization, the criss-cross algorithm is any of a family of algorithms for linear programming.
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This may affect many systems that otherwise require a lot of energy.Bertels, 2006. The amount of time that an object such as the ISS can remain safely in free-drift varies depending on moment of inertia, perturbation torques, tidal gradients, etc. The ISS itself generally can last about 45 minutes in this mode.
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PWscf (Plane-Wave Self-Consistent Field) is a set of programs for electronic structure calculations within density functional theory and density functional perturbation theory, using plane wave basis sets and pseudopotentials. The software is released under the GNU General Public License. The latest version QE-6.6 was released on 5 Aug 2020.
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The analysis in the previous section breaks down when the amplitude of the perturbation is large. The growth then becomes non-linear as the spikes and bubbles of the instability tangle and roll up into vortices. Then, as in the figure, numerical simulation of the full problem is required to describe the system.
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Directionality of a movement has an effect on how the motor task is performed (i.e. walking forward vs. walking backward, each uses different levels of contraction in different muscles). Researchers have measured EMG signals for perturbation applied in multiple directions in order to identify muscle synergies that are present for all directions.
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Neuroimage, 43(2), 329-336 studied activation related to external perturbation and suggested prefrontal cortex to be involved in adequate allocation of visuospatial attention. Zwergal A et al. 2012 Zwergal, A., Linn, J., Xiong, G., Brandt, T., Strupp, M., & Jahn, K. (2012). Aging of human supraspinal locomotor and postural control in fMRI.
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PDF Another top-down influence upon N100 has been suggested to be efference copies from a person's intended movements so that the stimulation that results from them are not processed. A person's own voice produces a reduced N100 as does the effect of a self-initiated compared to externally created perturbation upon balance.
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Examples of systems that can be solved with perturbations include systems with nonlinear contributions to the equations of motion, interactions between particles, terms of higher powers in the Hamiltonian/free energy. For physical problems involving interactions between particles, the terms of the perturbation series may be displayed (and manipulated) using Feynman diagrams.
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Its role as a master regulator of morphogenesis during human development makes it an ideal candidate for perturbation in malignant tissues. Specifically, Sox9 appears to induce invasiveness and therapy-resistance in prostate, colorectal, breast and other cancers, and therefore promotes lethal metastasis. Many of these oncogenic effects of Sox9 appear dose dependent.
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During these encounters, Vesta causes a gravitational perturbation of Arete, allowing the mass of Vesta to be directly determined. Photometric observations during 1984 showed a rotation period of 6.54 ± 0.02 hours and a brightness variation of 0.10 ± 0.01 in magnitude. The light curve shows "four well defined extrema with two asymmetric maxima".
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In mathematics, the Weyl–von Neumann theorem is a result in operator theory due to Hermann Weyl and John von Neumann. It states that, after the addition of a compact operator () or Hilbert–Schmidt operator () of arbitrarily small norm, a bounded self-adjoint operator or unitary operator on a Hilbert space is conjugate by a unitary operator to a diagonal operator. The results are subsumed in later generalizations for bounded normal operators due to David Berg (1971, compact perturbation) and Dan-Virgil Voiculescu (1979, Hilbert–Schmidt perturbation). The theorem and its generalizations were one of the starting points of operator K-homology, developed first by Lawrence G. Brown, Ronald Douglas and Peter Fillmore and, in greater generality, by Gennadi Kasparov.
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The renormalization procedure is a specific procedure to make these divergent integrals finite and obtain (and predict) finite values for physically measurable quantities. The Bogoliubov–Parasyuk theorem states that for a wide class of quantum field theories, called renormalizable field theories, these divergent integrals can be made finite in a regular way using a finite (and small) set of certain elementary subtractions of divergencies. The theorem guarantees that computed within the perturbation expansion Green's functions and matrix elements of the scattering matrix are finite for any renormalized quantum field theory. The theorem specifies a concrete procedure (the Bogoliubov–Parasyuk R-operation) for subtraction of divergences in any order of perturbation theory, establishes correctness of this procedure, and guarantees the uniqueness of the obtained results.
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In perturbation theory, quantities called probability amplitudes, which determine the probability for various physical processes to occur, are expressed as sums of infinitely many terms, where each term is proportional to a power of the coupling constant g: : A=A_0+A_1g+A_2g^2+A_3g^3+\dots. In order for such an expression to make sense, the coupling constant must be less than 1 so that the higher powers of g become negligibly small and the sum is finite. If the coupling constant is not less than 1, then the terms of this sum will grow larger and larger, and the expression gives a meaningless infinite answer. In this case the theory is said to be strongly coupled, and one cannot use perturbation theory to make predictions.
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In relativistic cosmology there is a freedom associated with the choice of threading frame, this frame choice is distinct from choice associated with coordinates. Picking this frame is equivalent to fixing the choice of timelike world lines mapped into each other, this reduces the gauge freedom it does not fix the gauge but the theory remains gauge invariant under the remaining gauge freedoms. In order to fix the gauge a specification of correspondences between the time surfaces in the real universe (perturbed) and the background universe are required along with the correspondences between points on the initial spacelike surfaces in the background and in the real universe. This is the link between the gauge-invariant perturbation theory and the gauge-invariant covariant perturbation theory.
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Jørgensen's list of peer-reviewed publications contains numerous self-contained articles which, in many cases, have become central sources within the field of electronic structure theory. His areas of research have been diverse and include work on multi-configurational self- consistent field (MCSCF) methods, Lagrangian techniques for molecular property calculations and analytic derivatives, time-independent and time-dependent linear and non-linear response function theory, coupled cluster perturbation theory, calculation of magnetic molecular properties using gauge invariant methods, showing and explaining the divergence of Møller–Plesset perturbation theory, benchmarking the accuracy of electronic structure models, basis set extrapolation for accurate calculations of energies, linear-scaling coupled cluster algorithms, optimization algorithms for Hartree–Fock and Kohn–Sham theory, and localization of Hartree–Fock orbitals.
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Dirac's theory was hugely successful in explaining both the emission and absorption of radiation by atoms; by applying second-order perturbation theory, it was able to account for the scattering of photons, resonance fluorescence, as well as non- relativistic Compton scattering. Nonetheless, the application of higher-order perturbation theory was plagued with problematic infinities in calculations. In 1928, Dirac wrote down a wave equation that described relativistic electrons—the Dirac equation. It had the following important consequences: the spin of an electron is 1/2; the electron g-factor is 2; it led to the correct Sommerfeld formula for the fine structure of the hydrogen atom; and it could be used to derive the Klein–Nishina formula for relativistic Compton scattering.
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Based on Bethe's intuition and fundamental papers on the subject by Shin'ichirō Tomonaga, Julian Schwinger, Richard Feynman and Freeman Dyson, it was finally possible to get fully covariant formulations that were finite at any order in a perturbation series of quantum electrodynamics. Shin'ichirō Tomonaga, Julian Schwinger and Richard Feynman were jointly awarded with the 1965 Nobel Prize in Physics for their work in this area. Their contributions, and those of Freeman Dyson, were about covariant and gauge-invariant formulations of quantum electrodynamics that allow computations of observables at any order of perturbation theory. Feynman's mathematical technique, based on his diagrams, initially seemed very different from the field-theoretic, operator-based approach of Schwinger and Tomonaga, but Freeman Dyson later showed that the two approaches were equivalent.
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The ice shelves remain in four basins along the coast: Dryglaski, Edgeworth, Pyke and Sjögren. All of them are losing mass except for the Pyke Glacier. The ice shelf collapse in 2002 triggered a perturbation of a massive accelerated flow. The instability of the ice shelves' mass can be traced back to changes in climate.
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Moreover, the solution is unique and constitutes a linear dynamic feedback control law that is easily computed and implemented. Finally the LQG controller is also fundamental to the optimal perturbation control of non-linear systems. The LQG controller itself is a dynamic system like the system it controls. Both systems have the same state dimension.
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Göttingen Math.-Phys. Kl. II 1962 (1962), 1–20. (for smooth twist maps) and Vladimir Arnold in 1963V. I. Arnold, "Proof of a theorem of A. N. Kolmogorov on the preservation of conditionally periodic motions under a small perturbation of the Hamiltonian [Малые знаменатели и проблема устойчивости движения в классической и небесной механике]," Uspekhi Mat.
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This is described as dynamic (or ordinary) stability. A Maclaurin spheroid of eccentricity greater than 0.952887 is dynamically unstable. Even if it is composed of an inviscid fluid and has no means of losing energy, a suitable perturbation will grow (at least initially) exponentially. Dynamic instability implies secular instability (and secular stability implies dynamic stability).
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Integrated with quantified changes of phenotype induced by the perturbation, molecular phenotyping can identify pathways that contribute to the phenotypic changes. Currently molecular phenotyping uses RNA sequencing and mRNA expression to infer pathway activities. Other technologies and readouts such as mass spectrometry and protein abundance or phosphorylation levels can be potentially used as well.
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Henryk A. Witek is a chemist of Polish origin, and is a Professor of Chemistry in the National Chiao Tung University, Hsinchu, Taiwan. He obtained his scientific degrees from the Jagiellonian University (MS) and the University of Tokyo (PhD). His research interests encompass quantum and physical chemistry, applied linear algebra, as well as perturbation theory.
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PC-SAFT is an equation of state that is based on statistical associating fluid theory (SAFT). Like other SAFT equations of state, it makes use of statistical mechanical methods (in particular perturbation theory).Chapman, Walter G., et al. "SAFT: Equation-of-state solution model for associating fluids." Fluid Phase Equilibria 52 (1989): 31-38.
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Yambo relies on many-body perturbation theory and time-dependent density functional theory. Quasiparticle energies are calculated within the GW approximation for the self energy. Optical properties are calculated either by solving the Bethe–Salpeter equationBethe-Salpeter equation: the origins or by using the adiabatic local density approximation within time-dependent density functional theory.
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Ecosystems are dynamic entities. They are subject to periodic disturbances and are in the process of recovering from some past disturbance. When a perturbation occurs, an ecosystem responds by moving away from its initial state. The tendency of an ecosystem to remain close to its equilibrium state, despite that disturbance, is termed its resistance.
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In a large class of singularly perturbed problems, the domain may be divided into two or more subdomains. In one of these, often the largest, the solution is accurately approximated by an asymptotic seriesR.B. Dingle (1973), Asymptotic Expansions: Their Derivation and Interpretation, Academic Press. found by treating the problem as a regular perturbation (i.e.
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PAC now detects both γ-quanta and evaluates the first as a start signal, the second as a stop signal. Single spectra in 90° and 180° showing the perturbation effect. Now one measures the time between start and stop for each event. This is called coincidence when a start and stop pair has been found.
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The theory presented a radical rethinking of the foundations of physical laws. By the 1940s it had become clear that the proton and the neutron were not pointlike particles like the electron. Their magnetic moment differed greatly from that of a pointlike spin-½ charged particle, too much to attribute the difference to a small perturbation.
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Follow-up work published in 2008 did not confirm the original candidate but instead found evidence of a planet in a . This object has a minimum estimated mass at least three times that of the planet Jupiter. Perturbation by the secondary star in this system may have driven the planet into a high inclination orbit.
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This is a stable equilibrium. The response to a small perturbation is forces that tend to restore the equilibrium. If more than one stable equilibrium state is possible for a system, any equilibria whose potential energy is higher than the absolute minimum represent metastable states. Diagram of a ball placed in a neutral equilibrium.
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In Advances in Experimental Medicine and Biology, Volume 629. (D. Sternad (Ed) A multidisciplinary approach to motor control). Springer, Heidelberg. Further work at Haskins Labs using a combination of novel perturbation techniques, kinematic and intramuscular recordings discovered that the control and coordination of complex speech gestures was also based on functional synergies or coordination structures.
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The Blasius solution is not unique from a mathematical perspective, as Ludwig Prandtl himself noted it in his transposition theorem and analyzed by series of researchers such as Keith Stewartson, Paul A. Libby.Libby, Paul A., and Herbert Fox. "Some perturbation solutions in laminar boundary-layer theory." Journal of Fluid Mechanics 17.3 (1963): 433-449.
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JETP 45, 216 (1977)]. N-th order contribution of perturbation theory into any quantity can be evaluated at large N in the saddle-point approximation for functional integrals and is determined by instanton configurations. This contribution behaves usually as N! in dependence on N and is frequently associated with approximately the same (N!) number of Feynman diagrams.
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Sheldon, R.A.; Enzyme immobilisation: The quest for optimum performance; Adv. Synth. Catal., 2007, 349, 387-394. The physical aggregates are held together by covalent bonding without perturbation of their tertiary structure, that is without denaturation. Subsequent cross-linking of these physical aggregates renders them permanently insoluble while maintaining their pre-organized superstructure, and, hence their catalytic activity.
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A. N. Kolmogorov, "On the Conservation of Conditionally Periodic Motions under Small Perturbation of the Hamiltonian [О сохранении условнопериодических движений при малом изменении функции Гамильтона]," Dokl. Akad. Nauk SSR 98 (1954). This was rigorously proved and extended by Jürgen Moser in 1962J. Moser, "On invariant curves of area- preserving mappings of an annulus," Nachr. Akad. Wiss.
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In some cases, chiral perturbation theory has been successful in describing the interactions between hadrons in the non-perturbative regime of the strong interaction. For instance, it can be applied to few-nucleon systems, and at next-to-next-to- leading order in the perturbative expansion, it can account for three-nucleon forces in a natural way.
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Part of the resistance to perturbation is passive, by means of the nonlinear increase in passive tension and joint torques produced by muscular and other soft tissues. Tissue prestress is a preflexive property that constitutes a basal level of passive tension which, due to its presence in antagonistic tissues of a joint, increases joint passive stiffness and stability.
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For the Stoics, Pathos (Passion) is a Perturbation which man has to overcome in a similar manner to Kierkegaard's concept of Objective Truth., Kierkegaard and the Greek World: Aristotle and other Greek authors. According to Kierkegaard, the human self desires that which is beyond reason. Desire itself appears to be a desire for the infinite, as Plato once wrote.
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Durrer was born in Kerns. She earned her high school diploma at Kantonales Lehrerseminar, and studied at the University of Zürich. She completed her PhD on perturbation theory with Norbert Straumann at the University of Zürich in 1988. She was a postdoctoral researcher at the University of Cambridge for a year, before joining Princeton University in 1989.
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The HKB model states that dynamic instability causes switching to occur. HKB measures stability in the following ways: 1\. Critical slowing down. If a perturbation is applied to a system that takes it away from its stationary state, the time for a system to return to the stationary state (local relaxation time) is a measure of the system's stability.
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" In that interview Pinter "acknowledged that his plays—full of infidelity, cruelty, inhumanity, the lot—seem at odds with his domestic contentment. 'How can you write a happy play?' he said. 'Drama is about conflict and degrees of perturbation, disarray. I've never been able to write a happy play, but I've been able to enjoy a happy life.
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Varuna is a member of the "dynamically hot" class of classical KBOs, meaning that it has an orbital inclination greater than 4 degrees, the imposed maximum inclination for dynamically cold members of its population. As a classical KBO, Varuna is not in orbital resonance with Neptune and is also free from any significant perturbation by Neptune.
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Seilacher, A., 1984, Sedimentary structures tentatively attributed to seismic events, Marine Geology, 55, p. 1-12Van Loon, A.J., 2014, The life cycle of seismite research, Geologos v. 20, p. 61-66 Caution is urged when applying the term to features observed in the field, as similar-looking features may be products of either seismic or non-seismic perturbation.
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A classical result is that a lower semicontinuous function on a compact set attains its minimum. Results from variational analysis such as Ekeland's variational principle allow us to extend this result of lower semicontinuous functions on non-compact sets provided that the function has a lower bound and at the cost of adding a small perturbation to the function.
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It is then important to fit the different pieces of the model that were worked out using different algorithms. The Lazarus Project linked the parts on a spacelike hypersurface at the time of the merger. Results from the calculations can include the binding energy. In a stable orbit the binding energy is a local minimum relative to parameter perturbation.
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Maron develops genetic algorithms that predict the structure of molecular crystals using the principles of survival of the fittest. Maron's work uses density functional theory and many body perturbation theory to study complex atomic systems. She has investigated the GW approximation for molecules. The materials investigated by Marom can be used for dye-sensitized solar cells.
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The topology of an interactome makes certain predictions how a network reacts to the perturbation (e.g. removal) of nodes (proteins) or edges (interactions). Such perturbations can be caused by mutations of genes, and thus their proteins, and a network reaction can manifest as a disease. A network analysis can identify drug targets and biomarkers of diseases.
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Since it is time-consuming to calculate the energy for a molecule, it is even more time-consuming to calculate them for the entire list of points in the Brillouin zone. Calculations can use the Hartree-Fock method, some post-Hartree-Fock methods, particularly Møller-Plesset perturbation theory to second order (MP2) and density functional theory (DFT).
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Pionium is an exotic atom consisting of one and one meson. It can be created, for instance, by interaction of a proton beam accelerated by a particle accelerator and a target nucleus. Pionium has a short lifetime, predicted by chiral perturbation theory to be . It decays mainly into two mesons, and to a smaller extent into two photons.
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Ganymede's magnetic field is probably created by convection within its liquid iron core. The meager magnetic field is buried within Jupiter's much larger magnetic field and would show only as a local perturbation of the field lines. The satellite has a thin oxygen atmosphere that includes O, O2, and possibly O3 (ozone). Atomic hydrogen is a minor atmospheric constituent.
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Although it's clear that humans are constantly adjusting their speech while birds are believed to have crystallized their song upon reaching adulthood. He tested this idea by using headphones to alter a Bengalese finch's auditory feedback. The bird actually corrected for up to 40% of the perturbation. This provides strong support for error learning in humans.
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This age- structured growth model suggests a steady-state, or stable, age-structure and growth rate. Regardless of the initial population size, N_0, or age distribution, the population tends asymptotically to this age-structure and growth rate. It also returns to this state following perturbation. The Euler- Lotka equation provides a means of identifying the intrinsic growth rate.
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The most striking application of the theory is Hawking's prediction that Schwarzschild black holes radiate with a thermal spectrum. A related prediction is the Unruh effect: accelerated observers in the vacuum measure a thermal bath of particles. This formalism is also used to predict the primordial density perturbation spectrum arising from cosmic inflation, i.e. the Bunch-Davies vacuum.
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Myrf has been shown to be significantly downregulated in a mouse model carrying the same mutation in the NPC1 protein that is underlying Niemann-Pick type C1 disease, a neurodegenerative process in which dysmyelination is a main pathogenic factor. A perturbation of oligodendrocyte maturation and myelination therefore might be an underlying reason for the neurological deficits.
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The 1970s saw the development of non-perturbative methods in non-Abelian gauge theories. The 't Hooft–Polyakov monopole was discovered by 't Hooft and Alexander Polyakov, flux tubes by Holger Bech Nielsen and Poul Olesen, and instantons by Polyakov and coauthors. These objects are inaccessible through perturbation theory. Supersymmetry also appeared in the same period.
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In physics, particularly in quantum perturbation theory, the matrix element refers to the linear operator of a modified Hamiltonian using Dirac notation. The matrix element considers the effect of the newly modified Hamiltonian (i.e. the linear superposition of the unperturbed Hamiltonian plus interaction potential) on the quantum state. Matrix elements are important in atomic, nuclear and particle physics.
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However, because the signal depends on the uniformity of the perturbation, the extraction of such parameters must be treated with care.S. Koeppen and P. Handler,"Field Inhomogeneity in Electroreflectance," Phys. Rev. 187, 1182-1185 (1969). doi:10.1103/PhysRev.187.1182D.E. Aspnes and A. Frova, "Influence of Spatially Dependent Perturbations on Modulated Reflectance and Absorption of Solids," Solid State Comm.
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This is related to the idea of response diversity where a suite of species will exhibit differential responses to a given environmental perturbation. When considered together, they create a stabilizing function that preserves the integrity of a service.Elmqvist, T., C. Folke, M. Nyström, G. Peterson, J. Bengtsson, B. Walker and J. Norberg. 2003. Response diversity, ecosystem change, and resilience.
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Lyapunov–Schmidt reduction has been used in economics, natural sciences, and engineering often in combination with bifurcation theory, perturbation theory, and regularization. LS reduction is often used to rigorously regularize partial differential equation models in chemical engineering resulting in models that are easier to simulate numerically but still retain all the parameters of the original model.
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Its unstable equilibrium position is obtained by rotating the figure 180° about a horizontal axis. Theoretically, it will rest there, but the smallest perturbation will bring it back to the stable point. The mathematical gömböc has sphere-like properties. In particular, its flatness and thinness are minimal, and this is the only type of nondegenerate object with this property.
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In physics, the stochastic vacuum model is a nonperturbative, phenomenological approach to derive cross section in quantum chromodynamics. It is deemed impossible to calculate the vacuum averages of gauge-invariant quantities in QCD in a closed form, e.g. using the path integrals. But standard perturbation theory techniques don't work at distances, where the running coupling constant reaches 1.
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It might appear from the above that all nuclei of the same nuclide (and hence the same γ) would resonate at exactly the same frequency. This is not the case. The most important perturbation of the NMR frequency for applications of NMR is the "shielding" effect of the surrounding shells of electrons.Principle of Shielding and Deshielding . NMRCentral.
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Because the perturbing force is different in direction and magnitude on opposite sides of the orbit, it produces a change in the shape of the orbit. In astronomy, perturbation is the complex motion of a massive body subject to forces other than the gravitational attraction of a single other massive body.Bate, Mueller, White (1971): ch. 9, p. 385.
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Due to their large size, Rydberg atoms can exhibit very large electric dipole moments. Calculations using perturbation theory show that this results in strong interactions between two close Rydberg atoms. Coherent control of these interactions combined with their relatively long lifetime makes them a suitable candidate to realize a quantum computer. In 2010 two-qubit gates were achieved experimentally.
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Calypte is a genus of hummingbirds. It consists of two small species. Calypte face challenges of maintaining stability when flying near the Earth's surface, and tail Is used to offset aerial perturbation. Hummingbirds as Calypte have visual characteristics that are found in predatory as well as prey species, which means that they can be either predators or preys.
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In this diagram, a kaon, made of an up and strange antiquark, decays both weakly and strongly into three pions, with intermediate steps involving a W boson and a gluon, represented by the blue sine wave and green spiral, respectively. When calculating scattering cross-sections in particle physics, the interaction between particles can be described by starting from a free field that describes the incoming and outgoing particles, and including an interaction Hamiltonian to describe how the particles deflect one another. The amplitude for scattering is the sum of each possible interaction history over all possible intermediate particle states. The number of times the interaction Hamiltonian acts is the order of the perturbation expansion, and the time-dependent perturbation theory for fields is known as the Dyson series.
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They are called Newtonian gauges because \Psi is the Newtonian gravitational potential of classical Newtonian gravity, which satisfies the Poisson equation abla^2\Psi=4\pi G\rho for non- relativistic matter and on scales where the expansion of the universe may be neglected. It includes only scalar perturbations of the metric: by the scalar- vector-tensor decomposition these evolve independently of the vector and tensor perturbations and are the predominant ones affecting the growth of structure in the universe in cosmological perturbation theory. The vector perturbations vanish in cosmic inflation and the tensor perturbations are gravitational waves, which have a negligible effect on physics except for the so-called B-modes of the cosmic microwave background polarization. The tensor perturbation is truly gauge independent, since it is the same in all gauges.
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In 1981, Bartlett returned to Gainesville, as a Professor of Chemistry and Physics, and then in 1988 rose to the rank of Graduate Research Professor. Bartlett has been widely recognized as a pioneer of rigorous many-body methods for electron correlation, in particular, many-body perturbation and coupled cluster methods, which are today’s central computational tool for accurate electronic structure predictions. Bartlett and his coworkers were the first to formulate and implement coupled cluster theory with all single and double excitation operators (CCSD) in 1982, followed by triple (CCSDT) in 1987, quadruple (CCSDTQ), and even quintuple (CCSDTQP) excitation operators, and also many-body perturbation methods up to the sixth order. He developed a version of Feynman diagrams that both expedited the derivation of the equations and helped to visualize the physics of electron correlation.
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The underlying function of proteins belonging to the SAPLIP group is to interact with membrane bilayers, either by perturbation (without permeabilization), permeabilization of the membrane or binding to the membrane. Notable members of the SAPLIP family include granulysin (antimicrobial), pulmonary surfactant-associated protein B (pulmonary surfactant regulation) and the saposins (sphingolipid degradation) of which SAPLIPs are named after. Specific to the PSI, it has been shown that PSI is involved in mediating interactions of the PSI, both alone and in combination with the PSI’s parent enzyme, with phospholipid membranes at acidic pH (~pH 4.5). Specifically, the PSI is involved in vacuolar targeting and membrane perturbation; this enables both the storage and movement of the AP into protein storage compartments within vacuoles contained in both leaves and roots of barley and cardoon.
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The Nekhoroshev estimates are an important result in the theory of Hamiltonian systems concerning the long-time stability of solutions of integrable systems under a small perturbation of the Hamiltonian. The first paper on the subject was written by Nikolay Nekhoroshev in 1971. The theorem complements both the KAM theorem and the phenomenon of instability for nearly integrable Hamiltonian systems, sometimes called Arnold Diffusion, in the following way: The KAM Theorem tells us that many solutions to nearly integrable Hamiltonian systems persist under a perturbation for all time, while, as Vladimir Arnold first demonstrated in 1964, some solutions do not stay close to their integrable counterparts for all time. The Nekhoroshev estimates tell us that, nonetheless, all solutions stay close to their integrable counterparts for an exponentially long time.
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In 2010, with Dmitriy Tseliakhovich, he pointed to an unprecedented effect in cosmological perturbation theory for the calculation of the formation of the first structures in the universe. It is based on the fact that the speed of sound in baryonic matter (as opposed to dark matter) decreased drastically (from relativistic to thermal velocities) when the first atoms formed (recombination epoch), which leads to supersonic velocity currents of baryonic matter (which under gravitational influence of faster dark matter moves) and quadratic perturbation terms. According to Hirata and Tseliakhovich, this leads to a suppression of the formation of the first structures with observable effects. With others, he initiated a program for analyzing information from astronomical data for possible inferences on fundamental questions of particle physics and what it might suggest for creating new observation programs.
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Already in two dimensions, the 2-opt heuristic might take exponentially many iterations until finding a local optimum. In this setting, one can analyze the perturbation model where the vertices v_1,\dots,v_n are independently sampled according to probability distributions with probability density function f_1,\dots,f_n : [0,1]^d \rightarrow [0,\theta]. For \theta = 1, the points are uniformly distributed.
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The orbital period of this asteroid is close to a 2:1 commensurability with Jupiter, which made it useful for perturbation measurements to derive the mass of the planet. Photometry measurements made at the Oakley Observatory during 2006 produced a lightcurve with a rotation period of and an amplitude of in magnitude. It has an estimated span of and a mass of .
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Pyrrho. Ancient Greek skeptics were not "skeptics" in the contemporary sense of selective, localized doubt. Their concerns were epistemological, noting that truth claims could not be adequately supported, and psychotherapeutic, noting that beliefs caused mental perturbation. The Western tradition of systematic skepticism goes back at least as far as Pyrrho of Elis (b. circa 360 BCE) and arguably to Xenophanes (b.
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A phase response curve (PRC) illustrates the transient change (phase response) in the cycle period of an oscillation induced by a perturbation as a function of the phase at which it is received. PRCs are used in various fields; examples of biological oscillations are the heartbeat, circadian rhythms, and the regular, repetitive firing observed in some neurons in the absence of noise.
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Research in this program tackled fundamental questions about growth and form in cellular biology. Computational modelling was used to study how the control of development results from an interaction between each cell's genetic regulatory network and its inputs from neighbouring cells and its environment, and how the process proceeds reliably, while coping with unreliable components, perturbation, injury, and changing environments.
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These include the rise time (the time needed by the control system to reach the desired value after a perturbation), peak overshoot (the highest value reached by the response before reaching the desired value) and others (settling time, quarter-decay). Frequency domain specifications are usually related to robustness (see after). Modern performance assessments use some variation of integrated tracking error (IAE, ISA, CQI).
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The KAM theorem states that if the system is subjected to a weak nonlinear perturbation, some of the invariant tori are deformed and survive, while others are destroyed. Surviving tori meet the non-resonance condition, i.e., they have “sufficiently irrational” frequencies. This implies that the motion continues to be quasiperiodic, with the independent periods changed (as a consequence of the non-degeneracy condition).
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Julian Schwinger, winner of the 1965 Nobel Prize in Physics. Original caption: "His laboratory is his ballpoint pen." Julian Seymour Schwinger (; February 12, 1918 – July 16, 1994) was a Nobel Prize winning American theoretical physicist. He is best known for his work on quantum electrodynamics (QED), in particular for developing a relativistically invariant perturbation theory, and for renormalizing QED to one loop order.
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Evan O'Neill Kane (December 23, 1924 – March 23, 2006), known as E. O. Kane in his publications, was a physicist who established some of the basic understanding of the theory of semiconductors that are now used in consumer and other electronics. He was one of the main developers of the k·p perturbation theory which is used to calculate band structures.
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Freud concluded that sublimation could be a conflict between the need for satisfaction and the need for security without perturbation of awareness. In an action performed many times throughout one's life, which firstly appears sadistic, though is ultimately refined into an activity which is of benefit to mankind.Geller, J.(2009). "Of Snips... and Puppy Dog Tails": Freud's Sublimation of Judentum.
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Dusty material ejected from this star is interacting with the surrounding interstellar medium, forming a bow shock as the star moves through the galaxy. The stand-off distance for this front is located at about from Theta Apodis. Theta Apodis has been identified as an astrometric binary, indicating that it has an orbiting companion that causes gravitational perturbation of the primary star.
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The standard map cannot have a homoclinic or heteroclinic connection. The practical consequence is that one cannot show the existence of a Smale's horseshoe in this system by a perturbation method, starting from a homoclinic or heteroclinic connection. Nevertheless, one can show that Smale's horseshoe exists in the standard map for many parameter values, based on crude rigorous numerical calculations.
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The model was presented and verified for a damaged beam with notch type damage, using first-order perturbation only, for the Euler–Bernoulli beam theory in the paper by Dixit and Hanagud (2011)Dixit, A., Hanagud, S., 2011. Single beam analysis of damaged beams verified using a strain energy based damage measure. International Journal of Solid and Structures 48, 592–602.
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In the theory of general relativity, linearized gravity is the application of perturbation theory to the metric tensor that describes the geometry of spacetime. As a consequence, linearized gravity is an effective method for modeling the effects of gravity when the gravitational field is weak. The usage of linearized gravity is integral to the study of gravitational waves and weak-field gravitational lensing.
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Predicting the overall orbit and position of Asbolus beyond a few thousand years is difficult because of errors in the known trajectory, error amplification by perturbations due to all of the gas giants, and the possibility of perturbation as a result of cometary outgassing and fragmentation. Compared to centaur 7066 Nessus, the orbit of Asbolus is currently much more chaotic.
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In his doctoral dissertation and numerous later publications, Rockafellar developed a general duality theory based on convex conjugate functions that centers on embedding a problem within a family of problems obtained by a perturbation of parameters. This encapsulates linear programming duality and Lagrangian duality, and extends to general convex problems as well as nonconvex ones, especially when combined with an augmentation.
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In 2006, they demonstrated a simple potential for exchange energies; the Becke–Johnson potential. She developed the exchange-hole dipole moment dispersion model (XDM), which describes intermolecular interactions. The model is a density functional model based on second-order perturbation theory, and uses the interaction of induced dipoles to model dispersion. Her PhD focussed on improving the accuracy and efficiency of computational chemistry.
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This activity pattern of neurons is a phenomenon seen in various neural circuits throughout the body and is seen in single neuron models and within clusters of neurons. Many of these models utilize phase response (resetting) curves where the oscillation of a neuron is perturbed and the effect the perturbation has on the phase cycle of a neuron is measured.
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First, the fields can be concentrated in a given direction. Second, they can be made to avoid or surround objects, returning without perturbation to their original path. These results are consistent with Maxwell's equations and are more than only ray approximation found in geometrical optics. Accordingly, in principle, these effects can encompass all forms of electromagnetic radiation phenomena on all length scales.
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Industrial & engineering chemistry research. 2002 Oct 30;41(22):5510-5.Gross J, Sadowski G. Modeling polymer systems using the perturbed-chain statistical associating fluid theory equation of state. Industrial & engineering chemistry research. 2002 Mar 6;41(5):1084-93.Jog PK, Chapman WG. Application of Wertheim's thermodynamic perturbation theory to dipolar hard sphere chains. Molecular Physics. 1999 Aug 10;97(3):307-19.
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Wiley-Interscience, 2005. decreasing significantly its capacity. 3Roam equipments overcome these limitations by incorporating a packet router, that re-routes packets intelligently in the network, in case such perturbation occurs. 3Roam solutions integrate seamlessly in corporate networks or network operators backhaul systems through their native packet architectures and allow for the smart inclusion of microwave links into an overall packet transport system.
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Mackenzie's has published 71 scientific papers listed in the INSPIRE-HEP Literature Database. The most widely cited of them, "Viability of lattice perturbation theory" in Physical Review D 48 (5), pp. 2250–2264 (1993) has been cited 589 times by March 2009. The second most widely cited, "On the elimination of scale ambiguities in perturbative quantum chromodynamics " Physical Review D 28 (1), pp.
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The equation of state is an important input into the flow equations. The speed of sound (speed of QGP-density oscillations) is currently under investigation in lattice computations. The mean free path of quarks and gluons has been computed using perturbation theory as well as string theory. Lattice computations have been slower here, although the first computations of transport coefficients have been concluded.
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He and his co-authors (Judy Kennedy, Edward Ott and James A. Yorke) have explored a temporally periodic flow with a time varying perturbation. In this flow, they showed the presence of indecomposable continua associated to the chaotic dynamics of the fluids. He was the first to prove numerically the Wada properties of the exit basins of an open Hamiltonian system.
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Hans-Jürgen Butt, Karlheinz Graf, and Michael Kappl, Physics and Chemistry of Interfaces, Wiley-VCH, Weinheim, 2003. The quantum mechanical description of a perturbation in a one-dimensional Fermi fluid is modelled by the Tomonaga-Luttinger liquid.D. Vieira et al., “Friedel oscillations in one- dimensional metals: From Luttinger’s theorem to the Luttinger liquid”, Journal of Magnetism and Magnetic Materials, vol.
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He studied theoretical cosmology, in particular cosmological perturbation theory, at graduate school at the University of Florida with advisor Prof. Jim Fry from 2001. He received his PhD in 2006. During his graduate studies he was a teaching assistant and lecturer in physics, he sat on the graduate student affairs committee, and he was an assistant coordinator for REU students.
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Another formulation of the composite fermion physics is through a Chern–Simons field theory, wherein flux quanta are attached to electrons by a singular gauge transformation. At the mean field approximation the physics of free fermions in an effective field is recovered. Perturbation theory at the level of the random phase approximation captures many of the properties of composite fermions.
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The Luttinger liquid model, proposed by Tomonaga and reformulated by J.M. Luttinger, describes electrons in one-dimensional electrical conductors under second-order interactions. and Elliot H. Lieb, proved in 1965, that electrons could be modeled as bosonic interactions. The response of the electron density to an external perturbation can be treated as plasmonic waves. This model predicts the emergence of spin–charge separation.
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In some form these considerations have a history of centuries in mathematics, but also in physics and engineering. For example, in the geometry of numbers a class of results called isolation theorems was recognised, with the topological interpretation of an open orbit (of a group action) around a given solution. Perturbation theory also looks at deformations, in general of operators.
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R McWeeny and GHF Diercksen, Self- consistent perturbation theory. II. Extension to open shells. The Journal of Chemical Physics 49, 4852–4856 (1968), Doi:10.1063/1.1669970 In spring 1965 he accepted an offer by Ludwig Biermann to join the Max-Planck-Institut für Physik und Astrophysik in Munich (since 1991: Max-Planck-Institut für Astrophysik in Garching) as Scientific Staff.
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This observation accounts for the peak in the wave function (and its probability density) near the turning points. Applications of the WKB method to Schrödinger equations with a large variety of potentials and comparison with perturbation methods and path integrals are treated in Müller-Kirsten.Harald J.W. Müller-Kirsten, Introduction to Quantum Mechanics: Schrödinger Equation and Path Integral, 2nd ed. (World Scientific, 2012).
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Although this solution has been verified with numerous observations, it is complicated, involving Chaos Theory mathematics, and has not been widely used. However, when incorporated into the NCEP forecast models using satellite surface wind data, it significantly improved the forecasts. The nonlinear solution, with explicit description of the finite perturbation coherent structure rolls constitutes a significant contribution to the theory of Chaos for organization of turbulence.
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A Kelvin wave (fluid dynamics) is also a long scale perturbation mode of a vortex in superfluid dynamics; in terms of the meteorological or oceanographical derivation, one may assume that the meridional velocity component vanishes (i.e. there is no flow in the north–south direction, thus making the momentum and continuity equations much simpler). This wave is named after the discoverer, Lord Kelvin (1879).
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Beginning in 1995, websites such as ZetaTalk have claimed that Nibiru or "Planet X" is a brown dwarf currently within our planetary system, soon to pass relatively close to Earth. Sitchin disagreed with the timing of passage. Sitchin also postulated that Pluto began life as Gaga, a satellite of Saturn which, due to perturbation caused by Nibiru's passing, was flung into orbit beyond Neptune.
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When the running coupling of the theory is small enough, then all required quantities may be computed in perturbation theory. Quantization schemes intended to simplify such computations (such as canonical quantization) may be called perturbative quantization schemes. At present some of these methods lead to the most precise experimental tests of gauge theories. However, in most gauge theories, there are many interesting questions which are non-perturbative.
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In perturbation theory, forces are generated by the exchange of virtual particles. The mechanics of virtual-particle exchange is best described with the path integral formulation of quantum mechanics. There are insights that can be obtained, however, without going into the machinery of path integrals, such as why classical gravitational and electrostatic forces fall off as the inverse square of the distance between bodies.
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This minor planet was named by the discoverer in honor of Sigmund Mauderli (1876–1962), Swiss astronomer and director of the Astronomical Institute at the University of Bern from 1921–1946. He devoted much of his time to orbit determination and perturbation computing of minor planets for the Astronomisches Rechen-Institut in Germany. The official was published by the Minor Planet Center on 1 October 1969 ().
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As the perturbation increases and the smooth curves disintegrate we move from KAM theory to Aubry–Mather theory which requires less stringent hypotheses and works with the Cantor-like sets. The existence of a KAM theorem for perturbations of quantum many-body integrable systems is still an open question, although it is believed that arbitrarily small perturbations will destroy integrability in the infinite size limit.
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String theory perturbation didn't restrict these p-branes. Thanks to supersymmetry, p-branes in supergravity gained understanding well beyond the limits of string theory. Armed with this new nonperturbative tool, Edward Witten and many others could show all of the perturbative string theories as descriptions of different states in a single theory that Witten named M-theory. Furthermore, he argued that M-theory's long wavelength limit, i.e.
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Motor learning research often considers variables that contribute to motor program formation (i.e., underlying skilled motor behaviour), sensitivity of error-detection processes, and strength of movement schemas (see motor program). Motor learning is "relatively permanent", as the capability to respond appropriately is acquired and retained. Temporary gains in performance during practice or in response to some perturbation are often termed motor adaptation, a transient form of learning.
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Thus naively taking the parameter to be zero changes the very nature of the problem. In the case of differential equations, boundary conditions cannot be satisfied; in algebraic equations, the possible number of solutions is decreased. Singular perturbation theory is a rich and ongoing area of exploration for mathematicians, physicists, and other researchers. The methods used to tackle problems in this field are many.
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When perturbed, the oscillator responds by spiraling back into the limit cycle, but not necessarily at the same phase. This is because the oscillator is autonomous; it has no stable time reference. The phase is free to drift. As a result, any perturbation of the oscillator causes the phase to drift, which explains why the noise produced by an oscillator is predominantly in phase.
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The lower boundary coincides with the ground (or, more precisely, a height above ground corresponding to its aerodynamic roughness). For the non-hydrostatic part of the mesoscale pressure perturbation, inhomogeneous Neumann conditions are imposed at that boundary. All other conditions at the lower boundary follow from the assumption that the –Obukhov similarity theory is valid. The one way interactive nesting facility is possible within MEMO.
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Second (MP2), third (MP3), and fourth (MP4) order Møller–Plesset calculations are standard levels used in calculating small systems and are implemented in many computational chemistry codes. Higher level MP calculations, generally only MP5, are possible in some codes. However, they are rarely used because of their cost. Systematic studies of MP perturbation theory have shown that it is not necessarily a convergent theory at high orders.
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Orbit models are typically propagated in time and space using special perturbation methods. This is performed by first modeling the orbit as a Keplerian orbit. Then perturbations are added to the model to account for the various perturbations that affect the orbit. Special perturbations can be applied to any problem in celestial mechanics, as it is not limited to cases where the perturbing forces are small.
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For relativistic matter, pressure and temperature are not independent variables, so the equation of state is a relation between the energy density and the pressure. This has been found through lattice computations, and compared to both perturbation theory and string theory. This is still a matter of active research. Response functions such as the specific heat and various quark number susceptibilities are currently being computed.
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Eccentricity varies primarily due to the gravitational pull of Jupiter and Saturn. However, the semi-major axis of the orbital ellipse remains unchanged; according to perturbation theory, which computes the evolution of the orbit, the semi-major axis is invariant. The orbital period (the length of a sidereal year) is also invariant, because according to Kepler's third law, it is determined by the semi-major axis.
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He has held visiting positions at several academic institutions, including the University of California, Santa Barbara, Kyoto University, and CERN. In 2005 he was elected a fellow of the American Physical Society for "contributions to Quantum Field Theory and String Theory, including string perturbation theory, supersymmetric Yang-Mills theory and AdS-CFT correspondence". In 1996 he married Jody Enders. In 2004 he became a U.S. citizen.
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CFD made a major break through in late 70s with the introduction of LTRAN2, a 2-D code to model oscillating airfoils based on transonic small perturbation theory by Ballhaus and associates. It uses a Murman-Cole switch algorithm for modeling the moving shock-waves.Murman, E.M. and Cole, J.D., "Calculation of Plane Steady Transonic Flows", AIAA Journal , Vol 9, No 1, pp. 114–121, Jan 1971.
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Restoration and restoration ecologists intend to return wetlands to their natural trajectory by aiding directly with the natural processes of the ecosystem. These direct methods vary with respect to the degree of physical manipulation of the natural environment and each are associated with different levels of restoration. Restoration is needed after disturbance or perturbation of a wetland. Disturbances include exogenous factors such as flooding or drought.
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E.B. Davis derived the GKSL with Markovian property master equations using perturbation theory and additional approximations, such as the rotating wave or secular, thus fixing the flaws of the Redfield equation. Davis construction is consistent with the Kubo-Martin- Schwinger stability criterion for thermal equilibrium i.e. the KMS state . An alternative approach to fix the Redfield has been proposed by J. Thingna, J.-S.
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MOLCAS contains codes for general and effective multiconfigurational SCF calculations at the Complete Active Space (CASSCF) level, but also employing more restricted MCSCF wave functions (RASSCF). It is also possible, at this level of theory, to optimize geometries for equilibrium and transition states using gradient techniques and to compute force fields and vibrational energies. MOLCAS also contains second order perturbation theory codes CASPT2 and RASPT2.
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As materials for the investigation (samples) are in principle all materials that can be solid and liquid. Depending on the question and the purpose of the investigation, certain framework conditions arise. For the observation of clear perturbation frequencies it is necessary, due to the statistical method, that a certain proportion of the probe atoms are in a similar environment and e.g. experiences the same electric field gradient.
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Denis Gratias graduated as a chemical engineer in 1970 at Chimie ParisTech. In 1978, Denis Gratias defended his PhD thesis at the Structural Metallurgy Laboratory (CNRS-ENSCP), entitled Cristallography of interfaces in homogeneous crystals and developed with Richard Portier a formalism of fast electron diffraction.D. Gratias and R. Portier, Time-like perturbation method in high-energy electron diffraction, Acta Cryst. A, A39 4, 576-584 (1983).
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The Bethe formula is only valid for energies high enough so that the charged atomic particle (the ion) does not carry any atomic electrons with it. At smaller energies, when the ion carries electrons, this reduces its charge effectively, and the stopping power is thus reduced. But even if the atom is fully ionized, corrections are necessary. Bethe found his formula using quantum mechanical perturbation theory.
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Multiple definitions and calculations of enrichment have been adopted by different researchers. Calculations of enrichment become more complex when multiple tracers are used simultaneously. Because enriched isotope preparations are never isotopically pure, i.e. they contain all the element’s isotopes in unnatural abundances, calculations of enrichment of multiple isotope tracers must account for the perturbation of each isotope ratio by the presence of the other tracers.
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The Lorentz force then bends the electron trajectories with the result that upward-moving-ev x B electrons congregate at B and downward-moving ones at A. The resulting current j = -en ve sheets generate magnetic field that enhances the original field and thus perturbation grows. Weibel instability is also common in astrophysical plasmas, such as collisionless shock formation in supernova remnants and \gamma-ray bursts.
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Solution of the Landau pole problem requires the calculation of the Gell-Mann–Low function at arbitrary and, in particular, its asymptotic behavior for . Diagrammatic calculations allow one to obtain only a few expansion coefficients , which do not allow one to investigate the function in the whole. Progress became possible after the development of the Lipatov method for calculating large orders of perturbation theory:L.N.Lipatov, Zh.Eksp.Teor.Fiz.
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Rossby wave instability in a Keplerian disk. Rossby Wave Instability (RWI) is a concept related to astrophysical accretion discs. In non-self-gravitating discs, for example around newly forming stars, the instability can be triggered by an axisymmetric bump, at some radius r_0, in the disc surface mass-density. It gives rise to exponentially growing non-axisymmetric perturbation in the vicinity of r_0 consisting of anticyclonic vortices.
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In practice, the linear equations that we work with are linearisations of more complicated governing equations such as the Navier–Stokes equations about some base state, with the linearisations carried out under the assumption that the perturbation quantity y is small. Transient growth may violate this assumption. When nonlinear effects are considered, then a system may be unstable even if the linearised system is stable.
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Q factor of a resonant cavity can be calculated using cavity perturbation theory and expressions for stored electric and magnetic energy. The electromagnetic fields in the cavity are excited via external coupling. An external power source is usually coupled to the cavity by a small aperture, a small wire probe or a loop.R. E. Collin, Foundations for Microwave Engineering, 2nd edition, IEEE Press, New York, NY, 2001.
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Elastic instability of a rigid beam supported by an angular spring. Elastic instability is a form of instability occurring in elastic systems, such as buckling of beams and plates subject to large compressive loads. There are a lot of ways to study this kind of instability. One of them is to use the method of incremental deformations based on superposing a small perturbation on an equilibrium solution.
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Beyond this idealization of massless quarks, the actual small quark masses also break the chiral symmetry explicitly as well (providing non- vanishing pieces to the divergence of chiral currents, commonly referred to as PCAC: partially conserved axial currents). The masses of the pseudoscalar meson octet are specified by an expansion in the quark masses which goes by the name of chiral perturbation theory. The internal consistency of this argument is further checked by lattice QCD computations, which allow one to vary the quark mass and confirm that the variation of the pseudoscalar masses with the quark masses is as dictated by chiral perturbation theory, effectively as the square-root of the quark masses. For the three heavy quarks: the charm quark, bottom quark, and top quark, their masses, and hence the explicit breaking these amount to, are much larger than the QCD spontaneous chiral symmetry breaking scale.
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An agroecosystem exists amid contexts including climate, soil, plant genetics, government policies, and the personal beliefs and predilections of the agriculturalist. Not only are these contexts too numerous to list in their entirety for any agroecosystem, but their interactions are so complex it is impossible to perfectly characterize a system, let alone predict the effect a given perturbation will have on the whole. At the same time, all of these contexts are dynamic, albeit at wildly diverging time scales, so the ecology of contexts for an agroecosystem is fundamentally mutable. An awareness of the ecology of contexts is helpful for agroecologists, as the nearly axiomatic acceptance dynamic, and thereby unperfectable, nature of agroecosystems precludes the often damaging notion of a best or ideal approach to agroecosystem management as well as an awareness of the complexity of the response that can result from any perturbation of the system.
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These perturbations are important, as they are responsible for the subtle physics that result in the cosmic microwave background anisotropy. In this epoch, the amplitude of perturbations that enter the horizon oscillate sinusoidally, with dense regions becoming more rarefied and then becoming dense again, with a frequency which is related to the size of the perturbation. If the perturbation oscillates an integral or half-integral number of times between coming into the horizon and recombination, it appears as an acoustic peak of the cosmic microwave background anisotropy. (A half-oscillation, in which a dense region becomes a rarefied region or vice versa, appears as a peak because the anisotropy is displayed as a power spectrum, so underdensities contribute to the power just as much as overdensities.) The physics that determines the detailed peak structure of the microwave background is complicated, but these oscillations provide the essence.
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The purpose of the interaction picture is to shunt all the time dependence due to H0 onto the operators, thus allowing them to evolve freely, and leaving only H1,I to control the time-evolution of the state vectors. The interaction picture is convenient when considering the effect of a small interaction term, H1,S, being added to the Hamiltonian of a solved system, H0,S. By utilizing the interaction picture, one can use time-dependent perturbation theory to find the effect of H1,I, e.g., in the derivation of Fermi's golden rule, or the Dyson series in quantum field theory: in 1947, Shin'ichirō Tomonaga and Julian Schwinger appreciated that covariant perturbation theory could be formulated elegantly in the interaction picture, since field operators can evolve in time as free fields, even in the presence of interactions, now treated perturbatively in such a Dyson series.
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This class of theories when linearized exhibits three polarization modes for the gravitational waves, of which two correspond to the massless graviton (helicities ±2) and the third (scalar) is coming from the fact that if we take into account a conformal transformation, the fourth order theory () becomes general relativity plus a scalar field. To see this, identify and use the field equations above to get Working to first order of perturbation theory: and after some tedious algebra, one can solve for the metric perturbation, which corresponds to the gravitational waves. A particular frequency component, for a wave propagating in the -direction, may be written as where and g() = d/d is the group velocity of a wave packet centred on wave-vector . The first two terms correspond to the usual transverse polarizations from general relativity, while the third corresponds to the new massive polarization mode of () theories.
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D T Whiteside (ed.) (1973), The Mathematical papers of Isaac Newton, Volume VI: 1684-1691, Cambridge University Press, at page 533. Newton did not give an explicit expression for the form of this "oval of another kind"; to an approximation, it combines the two effects of the central-elliptical variational orbit and the Keplerian eccentric ellipse. Their combination also continually changes its shape as the annual argument changes, and also as the evection shows itself in libratory changes in the eccentricity, and in the direction, of the long axis of the eccentric ellipse. The Variation is the second-largest solar perturbation of the Moon's orbit after the Evection, and the third-largest inequality in the motion of the Moon altogether; (the first and largest of the lunar inequalities is the equation of the centre, a result of the eccentricity - which is not an effect of solar perturbation).
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Perturbation theory develops an expression for the desired solution in terms of a formal power series in some "small" parameter – known as a perturbation series – that quantifies the deviation from the exactly solvable problem. The leading term in this power series is the solution of the exactly solvable problem, while further terms describe the deviation in the solution, due to the deviation from the initial problem. Formally, we have for the approximation to the full solution , a series in the small parameter (here called ), like the following: : A= A_0 + \varepsilon^1 A_1 + \varepsilon^2 A_2 + \cdots In this example, would be the known solution to the exactly solvable initial problem and represent the first-order, second- order and higher-order terms, which may be found iteratively by a mechanistic procedure. For small these higher-order terms in the series generally (but not always!) become successively smaller.
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In solid-state physics, the k·p perturbation theory is an approximated semi- empirical approach for calculating the band structure (particularly effective mass) and optical properties of crystalline solids. It is pronounced "k dot p", and is also called the "k·p method". This theory has been applied specifically in the framework of the Luttinger–Kohn model (after Joaquin Mazdak Luttinger and Walter Kohn), and of the Kane model (after Evan O. Kane).
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Parametric resonance is the parametrical resonance phenomenon of mechanical perturbation and oscillation at certain frequencies (and the associated harmonics). This effect is different from regular resonance because it exhibits the instability phenomenon. Parametric resonance occurs in a mechanical system when a system is parametrically excited and oscillates at one of its resonant frequencies. Parametric resonance takes place when the external excitation frequency equals twice the natural frequency of the system.
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Turbulence is flow characterized by recirculation, eddies, and apparent randomness. Flow in which turbulence is not exhibited is called laminar. The presence of eddies or recirculation alone does not necessarily indicate turbulent flow—these phenomena may be present in laminar flow as well. Mathematically, turbulent flow is often represented via a Reynolds decomposition, in which the flow is broken down into the sum of an average component and a perturbation component.
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Result of the linear stability analysis. The Stroh formalism provides an optimal form to solve a great variety of elastic problems. Optimal means that one can construct an efficient numerical procedure to solve the incremental problem. By solving the incremental boundary value problem, one finds the relations among the material and geometrical parameters of the problem and the perturbation modes by which the wave propagates in the material, i.e.
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Here, ka is the wave steepness, with k a characteristic wavenumber and a a characteristic wave amplitude for the problem under study. The fields η, Φ and u are assumed to be '(ka). The dynamic free-surface boundary condition can be evaluated in terms of quantities at as: The advantages of these Taylor-series expansions fully emerge in combination with a perturbation-series approach, for weakly non- linear waves .
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Microbend grating is a convenient method to couple light from one guided fiber mode into another. Due to its antisymmetric nature of perturbation, it can be used to couple only into antisymmetric modes. Microbend gratings are easily tunable for a wide range of wavelengths.J. N. Blake, B. Y. Kim, H. E. Engan, and H. J. Shaw, “Analysis of intermodal coupling in a two-mode fiber with periodic microbends”.
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In statistical mechanics, the cluster expansion (also called the high temperature expansion or hopping expansion) is a power series expansion of the partition function of a statistical field theory around a model that is a union of non-interacting 0-dimensional field theories. Cluster expansions originated in the work of . Unlike the usual perturbation expansion, it converges in some non-trivial regions, in particular when the interaction is small.
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Perturbation has been suggested as a reason that Neptune does not follow the 10,000:1 ratio of mass between the parent planet and collective moons as seen in all other known giant planets. One theory of the Earth-Moon system suggest that a second companion which formed at the same time as the Moon, was perturbed by the Moon early in the system's history, causing it to impact with the Moon.
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However, their orbital periods are all 90 days or less, indicating that they are orbiting close to the host star. The equilibrium temperature for the most distant planet, based on an assumed Bond albedo of 0.3, would be about ; significantly above the boiling point of water. The number of planets in the system is slightly uncertain. At the time of planet c's detection, it exerted the lowest gravitational perturbation.
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Additionally, because of the chronotropic perturbation and diminished LV filling seen in HFpEF the bradycardic effect of beta blockers may enable improved filling, reduce myocardial oxygen demand, and lower blood pressure. However, this effect also can contribute to diminished response to exercise demands and can result in an excessive reduction in heart rate.Impaired chronotropic and vasodilator reserves limit exercise capacity in patients with heart failure and a preserved ejection fraction.
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Graphical representation of alternative stable states and the direction of critical slowing down prior to a critical transition (taken from Lever et al. 2020). Top panels (a) indicate stability landscapes at different conditions. Middle panels (b) indicate the rates of change akin to the slope of the stability landscapes, and bottom panels (c) indicate a recovery from a perturbation towards the system's future state (c.I) and in another direction (c.II).
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The flare was observed visually by Richard Christopher Carrington and the geomagnetic storm was observed with the recording magnetograph at Kew Gardens. The same instrument recorded a crotchet, an instantaneous perturbation of the Earth's ionosphere by ionizing soft X-rays. This could not easily be understood at the time because it predated the discovery of X-rays (by Roentgen) and the recognition of the ionosphere (by Kennelly and Heaviside).
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George Sterman's research focuses on quantum field theory and its applications in quantum chromodynamics. With Steven Weinberg he proved the infrared finiteness of jet cross sections, thus proving that perturbation theory is a safe method in that regime. He also worked on reformulation and proof of factorization theorems with Stephen Libby, John C. Collins and Davison E. Soper. He authored a textbook entitled An Introduction to Quantum Field Theory in 1993.
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The next step in crossover experiment design is to propose labeled reactants. For a non-isotopic labeling method the smallest perturbation to the system will be by addition of a methyl group at an unreactive position. Predicting the products given by each mechanism will show whether or not a given crossover experiment design can distinguish between the mechanisms in question. This is particularly relevant when employing an isotopic label.
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All living organisms, whether unicellular or multicellular, exhibit homeostasis. To maintain dynamic equilibrium and effectively carry out certain functions, a system must detect and respond to perturbations. After the detection of a perturbation, a biological system normally responds through negative feedback that stabilize conditions by reducing or increasing the activity of an organ or system. One example is the release of glucagon when sugar levels are too low.
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The mass of Massalia is dependent on the mass of 4 Vesta and perturbation of 44 Nysa. Lightcurve analysis indicates that Massalia's pole points towards either ecliptic coordinates (β, λ) = (45°, 10°) or (β, λ) = (45°, 190°) with a 10° uncertainty. This gives an axial tilt of 45°in both cases. The shape reconstruction from lightcurves has been described as quite spherical with large planar, nonconvex parts of the surface.
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This point where the highest order term will no longer vanish in the limit \varepsilon to zero by becoming equally dominant to another term, is called significant degeneration; this yields the correct rescaling to make the remaining root visible. This choice yields :y^3 -y^2 + \varepsilon^2 = 0 . Substituting the perturbation series :y(\varepsilon) = y_0 + \varepsilon^2 y_1 + \varepsilon^4 y_2+\cdots yields :y_0^3 - y_0^2 = 0.
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Graphical representation of alternative stable states and the direction of critical slowing down prior to a critical transition (taken from Lever et al. 2020). Top panels (a) indicate stability landscapes at different conditions. Middle panels (b) indicate the rates of change akin to the slope of the stability landscapes, and bottom panels (c) indicate a recovery from a perturbation towards the system's future state (c.I) and in another direction (c.II).
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Within the liver the aldolase C isoform is unaffected and therefore hepatic metabolism is assumed to be normally functioning and compensatory processes may be operating. Compromised immunity has also been indicated, relating to the predominance or exclusivity of aldolase A in leukocytes. This was correlated with recurrent infection in the Sicilian case. Focal disruption of vital energy metabolism has thus far prevented complete investigation of non-catalytic perturbation.
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From 1990 to 1992 Head-Gordon worked as a postdoctoral member of technical staff at Bell Labs, studying protein folding and the perturbation theories of water with Frank Stillinger. She joined Lawrence Berkeley National Laboratory in 1992, where she worked as a staff scientist until 2001. In 2001 Head-Gordon was awarded the IBM-SUR Award. That year she became a faculty member of Bioengineering at University of California, Berkeley.
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In the theory of the strong interaction of the standard model, we describe the interactions between quarks and gluons. Due to the running of the strong coupling constant, we can apply perturbation theory in the coupling constant only at high energies. But In the low-energy regime of QCD, the degrees of freedom are no longer quarks and gluons, but rather hadrons. This is a result of confinement.
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The National Direction of Police Intelligence (DNIP) manages the National Police of Panama, to produce strategic and operational intelligence; knowledge of threats, challenges, worries, criminality and the social demands, to orient the taking of decisions in front of the factors of perturbation of the public order, the security and the defence, by part of the controls and the government. This direction is independent of the Direction of Judicial Investigation (D.I.J. ).
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In mathematics, particularly in linear algebra and applications, matrix analysis is the study of matrices and their algebraic properties. Some particular topics out of many include; operations defined on matrices (such as matrix addition, matrix multiplication and operations derived from these), functions of matrices (such as matrix exponentiation and matrix logarithm, and even sines and cosines etc. of matrices), and the eigenvalues of matrices (eigendecomposition of a matrix, eigenvalue perturbation theory).
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Her group have used computational methods to evaluate the interactions of green tea with cardiac muscle and the growth of hexagonal ice. They identified the excited states of biological chromophores using many-body perturbation theory. She studied the pressure-induced deformations of nanomaterials and how this impacted their optoelectronic properties. Understanding piezochromic effects is important to determine the potential of a material for applications such as stress sensors.
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Lindhard theoryN. W. Ashcroft and N. D. Mermin, Solid State Physics (Thomson Learning, Toronto, 1976), named after Danish professor Jens Lindhard, is a method of calculating the effects of electric field screening by electrons in a solid. It is based on quantum mechanics (first-order perturbation theory) and the random phase approximation. Thomas–Fermi screening can be derived as a special case of the more general Lindhard formula.
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Type I PRCs are also shown to fire more slowly towards the onset of firing. Examples of Models that exhibit Type I PRCs in weakly coupled neural oscillators include the Connor and the Morris–Lecar model. #Type II Phase Response Curves can have negative and positive regions. Due to this characteristic, Type II PRCs are able to advance or delay changes in phase pending on the timing of perturbation that occurs.
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The Kubo formula, named for Ryogo Kubo who first presented the formula in 1957 , is an equation which expresses the linear response of an observable quantity due to a time-dependent perturbation. Among numerous applications of the Kubo formula, one can calculate the charge and spin susceptibilities of systems of electrons in response to applied electric and magnetic fields. Responses to external mechanical forces and vibrations can be calculated as well.
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When produced, the seed parton is expected to undergo a parton shower, which may include a series of nearly-collinear splittings before the hadronization starts. Furthermore, the jet algorithm must be robust when it comes to fluctuations in the detector response. Theoretically, If a jet algorithm is not infrared and collinear safe, it can not be guaranteed that a finite cross-section can be obtained at any order of perturbation theory.
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If the poles move into the left half plane, the oscillation dies out exponentially to zero. If the poles move into the right half plane, the oscillation grows exponentially until something limits it. If the perturbation is very small, the magnitude of the equivalent Q is very large so that the amplitude changes slowly. If the perturbations are small and reverse after a short time, the envelope follows a ramp.
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The surface potentials at the source and drain ends are solved analytically with poly- depletion and quantum mechanical effects. The effect of finite body doping is captured through a perturbation approach. The analytic surface potential solution agrees closely with the 2-D device simulation results. If the channel doping concentration is low enough to be neglected, computational efficiency can be further improved by a setting a specific flag (COREMOD = 1).
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It is probably already possible to print these organs with 3D printers, but the cost is too high. Designing whole body biomimetic devices addresses a major reservation that pharmaceutical companies have towards organs-on-chips, namely the isolation of organs. As these devices become more and more accessible, the complexity of the design increases exponentially. Systems will soon have to simultaneously provide mechanical perturbation and fluid flow through a circulatory system.
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Statistical associating fluid theory (SAFT) equations of state predict the effect of molecular size and shape and hydrogen bonding on fluid properties and phase behavior. The SAFT equation of state was developed using statistical mechanical methods (in particular perturbation theory) to describe the interactions between molecules in a system. The idea of a SAFT equation of state was first proposed by Chapman et al. in 1988 and 1989.
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Different from the analysis on differentially expressed individual genes, another type of analysis focuses on differential expression or perturbation of pre-defined gene sets and is called gene set analysis. Gene set analysis demonstrated several major advantages over individual gene differential expression analysis. Gene sets are groups of genes that are functionally related according to current knowledge. Therefore, gene set analysis is considered a knowledge based analysis approach.
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A mutation located in SMAD7 gene is a cause of susceptibility to colorectal cancer (CRC) type 3. Perturbation of Smad7 and suppression of TGF-β signaling was found to be evolved in CRC. Case control studies and meta-analysis in Asian and European populations also provided evidence that this mutation is associated with colorectal cancer risk. TGF-β is one of the important growth factors in pancreatic cancer.
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A morphodynamic system consists of a coupling of two homeodynamic systems such that the constraint dissipation of each complements the other, producing macroscopic order out of microscopic interactions. Morphodynamic systems require constant perturbation to maintain their structure, so they are relatively rare in nature. The paradigm example of a morphodynamic system is a Rayleigh–Bénard cell. Other common examples are snowflake formation, whirlpools and the stimulated emission of laser light.
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In similar in vitro experiments, it was found that the threshold forces required to prevent mitosis are in excess of 100 nN. At threshold forces the cell suffers a loss of cortical F-actin uniformity, which further amplifies the susceptibility to applied force. These effects potentiate distortion of cell dimensions and subsequent perturbation of mitotic progression via spindle defects. Release of stable focal adhesions is another important aspect of mitotic rounding.
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In a mouse model carrying the underlying mutation for Niemann- Pick type C1 disease in the NPC1 protein, the expression of Myelin gene Regulatory Factor (MRF) has been shown to be significantly decreased. MRF is a transcription factor of critical importance in the development and maintenance of myelin sheaths. A perturbation of oligodendrocyte maturation and the myelination process might therefore be an underlying mechanism of the neurological deficits.
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Because the reradiated signal is normally small compared to the original signal, it only produces a small change, or perturbation, in the resulting element currents. The program then repeats the calculation again with the new element currents, getting new radiation fields. This process is repeated until resulting values converge. NEC uses a separate method to calculate the contribution of extended planes of material, like a wire mesh reflector.
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Keeping the above example in mind, one follows a general recipe to obtain the perturbation series. The perturbative expansion is created by adding successive corrections to the simplified problem. The corrections are obtained by forcing consistency between the unperturbed solution, and the equations describing the system in full. Write D for this collection of equations; that is, let the symbol D stand in for the problem to be solved.
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From the best fit one can estimate \tau ~ 3500 years with a broad uncertainty due to the relative short time interval of the sample. This parameter can be interpreted as the relaxation time of the system, i.e. the time the system needs to recover from a perturbation of species distribution. In the same framework, the estimated mean species lifetime is very close to the fitted temporal scale \tau.
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In cases of instability (as for the inverted double-well potential) this equation possesses negative eigenvalues indicative of this instability, i.e. decay. Application of the perturbation method of Dingle and Müller (applied originally to the Mathieu equation, i.e. a Schrödinger equation with cosine potential) requires exploitation of parameter symmetries of the Schrödinger equation for the quartic potential. One expands around one of the two minima of the potential.
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The analysis above is predicated on the laser operating in a steady-state at the laser threshold. However, this is not an assumption which can ever be fully satisfied. The problem is that the laser output power varies by orders of magnitude depending on whether the laser is above or below threshold. When very close to threshold, the smallest perturbation is able to cause huge swings in the output laser power.
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This is supported by the rhythmic behavior of the brain. Harmonic oscillators have the capability to reproduce a perturbation that happened in previous cycles. It follows that when the brain is unperturbed, such as during sleep, it is in essence rehearsing the perturbations of the day. Recent studies have confirmed that off wave states, such as slow-wave sleep, play a part in consolidation as well as REM sleep.
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If a beta function is positive, the corresponding coupling increases with increasing energy. An example is quantum electrodynamics (QED), where one finds by using perturbation theory that the beta function is positive. In particular, at low energies, , whereas at the scale of the Z boson, about 90 GeV, one measures . Moreover, the perturbative beta function tells us that the coupling continues to increase, and QED becomes strongly coupled at high energy.
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Ecosystems can shift from one state to another via a significant perturbation directly to state variables. State variables are quantities that change quickly (in ecologically-relevant time scales) in response to feedbacks from the system (i.e., they are dependent on system feedbacks), such as population densities. This perspective requires that different states can exist simultaneously under equal environmental conditions, since the ball moves only in response to a state variable change.
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A variety of theoretical methods including density functional theory, k·p perturbation theory, and others are used to supplement and support the various experimental measurements described in the previous section, including interpreting, fitting, and extrapolating these measurements. Some of these theoretical methods can also be used for predictions of effective mass in the absence of any experimental data, for example to study materials that have not yet been created in the laboratory.
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Quantifying the effects of climate variability and human activities on runoff for Kaidu River Basin in arid region of northwest China. Theoretical and Applied Climatology, 111(3-4), 537-545. doi:10.1007/s00704-012-0680-4 However, this is just one of the problems that the Kaidu River is responsible for. Northwest China has been subjected to affects from the Kaidu RIver because of global warming and water perturbation.
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Studies have shown a correlation between the temperature and the precipitation being the leading cause to these issues. Additionally, the Kaidu River resides in an arid zone, causing many different trends in temperature due to this climate change.Mupenzi, J. D., & Li, L. (2011). Impacts of global warming perturbation on water resources in arid zone: Case study of Kaidu River Basin in Northwest China. Journal of Mountain Science, 8(5), 704-710.
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In order to find the perturbation in the normal the tangent space must be correctly calculated.Mikkelsen, Simulation of Wrinkled Surfaces Revisited, 2008 (PDF) Most often the normal is perturbed in a fragment shader after applying the model and view matrices. Typically the geometry provides a normal and tangent. The tangent is part of the tangent plane and can be transformed simply with the linear part of the matrix (the upper 3x3).
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It is theorized that, due to the atmospheric mixing that results, the air temperature perturbation within the UHI is generally minimal or nonexistent during the day, though the surface temperatures can reach extremely high levels. At night, the situation reverses. The absence of solar heating leads to the decrease of atmospheric convection and the stabilization of urban boundary layer. If enough stabilization occurs, an inversion layer is formed.
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The problem is ill-conditioned when the polynomial has a multiple root. For instance, the polynomial x2 has a double root at x = 0\. However, the polynomial x2 − ε (a perturbation of size ε) has roots at ±√ε, which is much bigger than ε when ε is small. It is therefore natural to expect that ill- conditioning also occurs when the polynomial has zeros which are very close.
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To define StO_2 \, (tissue oxygen saturation) (or TSI \, (tissue saturation index)), it is necessary to define a distribution of arteries and veins in tissue. an arterial-venous blood volume ratio of 20%/80% can be adopted.S. Nioka, S. Wen, J. Zhang, J. Du, X. Intes, Z. Zhao, and B. Chance, Simulation study of breast tissue hemodynamics during pressure perturbation. Oxygen Transport to Tissue XXVI 566, 17-22, 2006.
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The theory of phase reduction method was first introduced in the 1950s, the existence of periodic solutions to nonlinear oscillators under perturbation, has been discussed by Malkin in, in the 1960s, Winfree illustrated the importance of the notion of phase and formulated the phase model for a population of nonlinear oscillators in his studies on biological synchronization. Since then, many researchers have discovered different rhythmic phenomena related to phase reduction theory.
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Cooper, A.; Johnson, C. M.; Lakey, J. H.; Nollmann, M. Heat does not come in different colours: entropy-enthalpy compensation, free-energy windows, quantum confinement, pressure perturbation calorimetry, solvation and the multiple causes of heat capacity effects in biomolecular interactions. Biophys. Chem. 2001, 93, 215–230. In response to the criticisms, investigators have stressed that compensatory phenomena are real, but appropriate and in-depth data analysis is always needed.
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He also demonstrated that the 4d N=4 supersymmetric gauge theory is power counting finite, proving that this theory is scale invariant to all orders of perturbation theory, the first example of a field theory where all the infinities in Feynman diagrams cancel. Among his students at Berkeley are Joseph Polchinski, Michio Kaku, Charles Thorn and Hessamaddin Arfaei. Stanley Mandelstam died in his Berkeley apartment in June, 2016.
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He was the founder of and/or chief scientific adviser to a number of companies, including Flow Research, Ibrix (now part of HPQ), Vector Technologies, and Exa Corp. He has been awarded 6 patents and has written over 400 archival papers. With Carl M. Bender he wrote Advanced Mathematical Methods for Scientists and Engineers: Asymptotic Methods and Perturbation Theory, a standard text on mathematical methods for scientists. Book review.
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Bred vectors are created by adding initially random perturbations to a nonlinear model. The control (unperturbed) and the perturbed models are integrated in time, and periodically the control solution is subtracted from the perturbed solution. This difference is the bred vector. The vector is scaled to be the same size as the initial perturbation, and is then added back to the control to create the new perturbed initial condition.
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God has chosen the specific day to reveal the faith and devotion of Narasinga Muniyaraiyar. On one such Thiruvathirai puja day, a devotee attended puja with holy ashes smeared on his plain naked body. His presence gave rise to unusual perturbation among other devotees. Instead of developing detestation at the nudity, Muniyaraiyar rightly understood the amount of self-control and attitude of detachment developed by the devotee within himself.
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Projected UHF (PUHF) annihilates all spin contaminants from the self-consistent UHF wave function. The projected energy is evaluated as the expectation of the projected wave function. The spin-constrained UHF (SUHF) introduces a constraint into the Hartree–Fock equations of the form λ(Ŝ2 − S(S + 1)), which as λ tends to infinity reproduces the ROHF solution. All of these approaches are readily applicable to unrestricted Møller–Plesset perturbation theory.
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IX Special perturbations can be applied to any problem in celestial mechanics, as it is not limited to cases where the perturbing forces are small. Once applied only to comets and minor planets, special perturbation methods are now the basis of the most accurate machine-generated planetary ephemerides of the great astronomical almanacs.See, for instance, Jet Propulsion Laboratory Development Ephemeris. Special perturbations are also used for modeling an orbit with computers.
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Murray Gell-Mann always referred to Feynman diagrams as Stueckelberg diagrams, after a Swiss physicist, Ernst Stueckelberg, who devised a similar notation many years earlier. Stueckelberg was motivated by the need for a manifestly covariant formalism for quantum field theory, but did not provide as automated a way to handle symmetry factors and loops, although he was first to find the correct physical interpretation in terms of forward and backward in time particle paths, all without the path-integral. Historically, as a book-keeping device of covariant perturbation theory, the graphs were called Feynman–Dyson diagrams or Dyson graphs, because the path integral was unfamiliar when they were introduced, and Freeman Dyson's derivation from old-fashioned perturbation theory was easier to follow for physicists trained in earlier methods."It was Dyson's contribution to indicate how Feynman's visual insights could be used [...] He realized that Feynman diagrams [...] can also be viewed as a representation of the logical content of field theories (as stated in their perturbative expansions)".
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Interaction in the subatomic world: world lines of point-like particles in the Standard Model or a world sheet swept up by closed strings in string theory String theory can be seen as a generalization of quantum field theory where instead of point particles, string-like objects propagate in a fixed spacetime background, although the interactions among closed strings give rise to space-time in a dynamical way. Although string theory had its origins in the study of quark confinement and not of quantum gravity, it was soon discovered that the string spectrum contains the graviton, and that "condensation" of certain vibration modes of strings is equivalent to a modification of the original background. In this sense, string perturbation theory exhibits exactly the features one would expect of a perturbation theory that may exhibit a strong dependence on asymptotics (as seen, for example, in the AdS/CFT correspondence) which is a weak form of background dependence.
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Q is a computer software package for molecular dynamics (MD) simulation (current release: Q6). Unlike other MD codes, it has specialized since its conception (Marelius et al. 1998) on three specific types of free energy calculations. These calculations are based on the methods: empirical valence bond (EVB), free energy perturbation (FEP), and linear interaction energy (LIE), as well as, more recently, also path integral calculations using the bisection quantum classical path (BQCP) approach.
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The hurricane originated from a "cyclonic perturbation" near Barbados on October 4, as reported by local newspapers. On October 5, no closed circulation was evident in the system. In Colón, Panama, a report was sent to the Weather Bureau, reporting sinking barometric pressures on October 6. It was recognized as a tropical storm early on October 8, with winds of 40 mph (65 km/h), while located in the southwestern Caribbean Sea.
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The left copy represents flavor rotations among the left-handed quarks, while the right copy describes rotations among the right- handed quarks, while these, L and R, are completely independent of each other. The axial pieces of these symmetries are spontaneously broken so that the corresponding scalar fields are the requisite Nambu−Goldstone bosons. This model admits topological solitons called Skyrmions. Departures from exact chiral symmetry are dealt with in chiral perturbation theory.
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During that time, sophisticated methods of perturbation analysis were invented to calculate the deviations of orbits due to the influence of multiple bodies on a planet, moon, comet, or asteroid. The formalism was exact enough to allow mathematicians to predict the existence of the planet Neptune before it was observed. Instruments like GRAVITY provide a powerful probe for gravity force detection. Mercury's orbit, however, did not match that predicted by Newton's Law of Gravitation.
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Statistical coupling analysis or SCA is a technique used in bioinformatics to measure covariation between pairs of amino acids in a protein multiple sequence alignment (MSA). More specifically, it quantifies how much the amino acid distribution at some position i changes upon a perturbation of the amino acid distribution at another position j. The resulting statistical coupling energy indicates the degree of evolutionary dependence between the residues, with higher coupling energy corresponding to increased dependence.
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It is therefore assumed that a perturbation of SFK and RPTP balance due to ligand binding, leading to stronger kinase activity and hence accumulation of phosphorylated tyrosine residues, is needed for initiation of downstream signalling. Different mechanisms of how the balance is disturbed upon ligand binding have been suggested. The _induced proximity or aggregation model_ suggests that upon receptor-ligand binding multiple receptors aggregate. SFKs have multiple phosphorylation sites that regulate their catalytic activity.
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Kim and his research group are interested in both Theoretical/Computational Chemistry/Physics and Experimental Nanosciences. Specifically, the fields of research that they delve into include investigation of ab initio theory, Molecular dynamics simulation, Nonequilibrium thermodynamics and entanglement perturbation to provide understanding of intermolecular interactions, clusters, molecular recognition, drug design and nanomaterials. Furthermore, his team is developing functional molecules/materials for molecular sensing and engineering, nanodevices, green chemistry, DNA sequencing and energy storage.
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A Gaussian fixed point is a fixed point of the renormalization group flow which is noninteracting in the sense that it is described by a free field theory. The word Gaussian comes from the fact that the probability distribution is Gaussian at the Gaussian fixed point. This means that Gaussian fixed points are exactly solvable (trivially solvable in fact). Slight deviations from the Gaussian fixed point can be described by perturbation theory.
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In classical mechanics, anharmonicity is the deviation of a system from being a harmonic oscillator. An oscillator that is not oscillating in harmonic motion is known as an anharmonic oscillator where the system can be approximated to a harmonic oscillator and the anharmonicity can be calculated using perturbation theory. If the anharmonicity is large, then other numerical techniques have to be used. As a result, oscillations with frequencies 2\omega and 3\omega etc.
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E_i is the ionization potential of the atom. When the intensity of the laser is strong, the lowest-order perturbation theory is not sufficient to describe the MPI process. In this case, the laser field on larger distances from the nucleus is more important than the Coulomb potential and the dynamic of the electron in the field should be properly taken into account. The first work in this category was published by Keldysh.
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The main advantage of the Magnus proposal is that the truncated series very often shares important qualitative properties with the exact solution, at variance with other conventional perturbation theories. For instance, in classical mechanics the symplectic character of the time evolution is preserved at every order of approximation. Similarly, the unitary character of the time evolution operator in quantum mechanics is also preserved (in contrast, e.g., to the Dyson series solving the same problem).
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The window length L determines the longest periodicity captured by SSA. Trends can be extracted by grouping of eigentriples with slowly varying eigenvectors. A sinusoid with frequency smaller than 0.5 produces two approximately equal eigenvalues and two sine-wave eigenvectors with the same frequencies and \pi/2-shifted phases. Separation of two time series components can be considered as extraction of one component in the presence of perturbation by the other component.
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Traschen's research has included work with Robert Geroch critiquing certain approximations used in string theory and defining a "maximally reasonable" class of Pseudo-Riemannian manifolds called the Geroch–Traschen metrics. In black hole cosmology, Traschen is known for her work with David Kastor on multi-black-hole solutions to the equations of general relativity. She is also known for her work in cosmological perturbation theory, on integral constraint vectors of spacelike hypersurfaces.
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MRF is a transcription factor of critical importance in the development and maintenance of myelin sheaths. A perturbation of oligodendrocyte maturation and the myelination process might therefore be an underlying mechanism of the neurological deficits. Recent neuroimaging studies have shown patients with Niemann–Pick, type C to have a corpus callosum with microstructural abnormalities. Clear reductions in corpus callosum mean thickness and surface area have been shown when compared to age-matched controls.
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They travel along the characteristics of the equation. This feature qualitatively distinguishes hyperbolic equations from elliptic partial differential equations and parabolic partial differential equations. A perturbation of the initial (or boundary) data of an elliptic or parabolic equation is felt at once by essentially all points in the domain. Although the definition of hyperbolicity is fundamentally a qualitative one, there are precise criteria that depend on the particular kind of differential equation under consideration.
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Let us apply a very small magnetic field to the system in the critical point. A very small magnetic field is not able to magnetize a large coherent cluster, but with these fractal clusters the picture changes. It affects easily the smallest size clusters, since they have a nearly paramagnetic behaviour. But this change, in its turn, affects the next-scale clusters, and the perturbation climbs the ladder until the whole system changes radically.
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Kondo's model was derived using perturbation theory, but later methods used non-perturbative techniques to refine his result. These improvements produced a finite resistivity but retained the feature of a resistance minimum at a non-zero temperature. One defines the Kondo temperature as the energy scale limiting the validity of the Kondo results. The Anderson impurity model and accompanying Wilsonian renormalization theory were an important contribution to understanding the underlying physics of the problem.
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Some aspects of the security and control technologies are unleash sceptisism, critic and discussion, so for instance, unknown risks for organisms by electromagnetic radiation(de) Handout “RFID im Handel” of the Chamber of Industry and Commerce Hannover (IHK) or possible perturbation of the functioning of medical equipment by RFID labels.Study: RFID-Etikette können medizinische Geräte empfindlich stören“, Ärzteblatt Moreover, there are politically motivated reservations, anxieties and mistrust against a prevailing and illegitimated observation and control.
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Additionally, some activities, such as mining, implied much more widespread perturbation of natural conditions. Over the last 11,500 years or so humans have spread around Earth, increased in number, and profoundly altered the material world. They have taken advantage of global environmental conditions not of their own making. The end of the last glacial period – when as much as 30% of Earth's surface was ice-bound – led to a warmer world with more water ().
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Eventually Cargill was arrested, sentenced to death and hanged in Edinburgh on 27 July 1681. He is reported to have said to the crowd, "The Lord knows I go on this ladder with less fear and perturbation of mind, than ever I entered the pulpit to preach.". There is a monument to him at his birthplace in Rattray, Perthshire; and his name also appears on the Covenanters' Memorial near Maybole, South Ayrshire.
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This is the maximum distance at which Earth's gravitational influence is stronger than the more distant Sun and planets. Objects must orbit Earth within this radius, or they can become unbound by the gravitational perturbation of the Sun. Earth, along with the Solar System, is situated in the Milky Way and orbits about 28,000 light-years from its center. It is about 20 light-years above the galactic plane in the Orion Arm.
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The -principle is the most powerful method to solve underdetermined equations. The Riquier–Janet theory is an effective method for obtaining information about many analytic overdetermined systems. The method of characteristics can be used in some very special cases to solve partial differential equations. In some cases, a PDE can be solved via perturbation analysis in which the solution is considered to be a correction to an equation with a known solution.
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This raises philosophical problems: suppose that random physical processes happen on length scales both smaller than and bigger than the particle horizon. A physical process (such as an amplitude of a primordial perturbation in density) that happens on the horizon scale only gives us one observable realization. A physical process on a larger scale gives us zero observable realizations. A physical process on a slightly smaller scale gives us a small number of realizations.
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The last such approach was in 1976, the next will be in 2071. The Jovian orbits are highly elliptical and subject to intense Solar perturbation at apojove which eventually pulls the comet out of Jovian orbit for the cycle to begin anew. Simulations predict such a cycle is unstable, the object will either be captured into an encounter orbit (e.g. Shoemaker-Levy 9) or expelled into a new orbit which does not have periodic approaches.
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The perturbation terms are much easier to describe in this form. Predicting subsequent positions and velocities from initial values of position and velocity corresponds to solving an initial value problem. Numerical methods calculate the positions and velocities of the objects a short time in the future, then repeat the calculation ad nauseam. However, tiny arithmetic errors from the limited accuracy of a computer's math are cumulative, which limits the accuracy of this approach.
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After Fidel Castro's takeover of Cuba, the United States was unsure about the nation's new leader's political ideologies. Potential economic cooperation between the Nikita Khrushchev and Fidel Castro in 1959, leaders of the Soviet Union and Cuba, respectively, resulted in the immediate perturbation of the United States. The largest concern at this time was a Soviet satellite just 90 miles from the United States' mainland. The administration then began planning to intervene with this situation.
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The French physicist Marie-Antoinette Tonnelat published a paper in the early 1940s on the standard commutation relations for the quantized spin-2 field. She continued this work in collaboration with Erwin Schrödinger after World War II. In the 1960s Mendel Sachs proposed a generally covariant field theory that did not require recourse to renormalisation or perturbation theory. In 1965, Tonnelat published a book on the state of research on unified field theories.
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In 2015, Schellman was elected vice chair of the Commission on Particles and Fields within the International Union of Pure and Applied Physics. Schellman's research interests include, "future high-intensity neutrino experiments and the relation between cosmology and high-energy physics". She has collaborated on D-Zero and Tevatron experiments at Fermilab, researching the mass of top quarks and interactions of protons and anti- protons, and has extensively studied quantum chromodynamics perturbation theory.
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Nature Genetics is a scientific journal founded as part of the Nature family of journals in 1992. It publishes high quality research in genetics. The journal encompasses genetic and functional genomic studies on human traits and on other model organisms, including mouse, fly, nematode and yeast. Current emphasis is on the genetic basis for common and complex diseases and on the functional mechanism, architecture and evolution of gene networks, studied by experimental perturbation.
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The Dean number (De) is a dimensionless group in fluid mechanics, which occurs in the study of flow in curved pipes and channels. It is named after the British scientist W. R. Dean, who was the first to provide a theoretical solution of the fluid motion through curved pipes for laminar flow by using a perturbation procedure from a Poiseuille flow in a straight pipe to a flow in a pipe with very small curvature.
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This effect is often called Peierls instability: starting from a linear chain of equally spaced atoms Peierls considered first order perturbation theory with Bloch wave functions showing the instability, but he did not consider the self- consistency resulting in the transition to alternation of single and double bonds.R. E. Peierls: Zur Theorie der elektrischen und thermischen Leitfähigkeit von Metallen Ann. Phys. 4:121-148 (1930).R. E. Peierls: Quantum theory of solids Clarendon, Oxford (1955).
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In addition, they were more adaptable to airblast phenomena and produced a well defined blast wave without perturbation or ejecta; they also produced no crater. However, it was found that they lacked the high pressure associated with high explosives, and difficulties were encountered as the 20-ton gas balloon ruptured and another detonated unexpectedly during inflation. Ultimately ANFO was elected as a lower cost alternative to TNT for non-nuclear explosives tests.
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Like many other G protein-coupled receptors, the rhodopsin protein undergoes endocytosis following activation. Perturbation of endocytic regulation of rhodopsin has deleterious effects on photoreceptor cell physiology. In certain mutants, rhodopsin and its regulatory protein arrestin form stable complexes. As mentioned these complexes have a fatal effect; when taken up during endocytosis these complexes causes photoreceptor cell death, because the internalized rhodopsin is not degraded in the lysosome but instead accumulates in the late endosomes.
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Boussinesq equations) in that the flow need not be irrotational, and that no perturbation is used in deriving the equations. Hence, the GN equations satisfy the nonlinear boundary conditions exactly, and postulate the integrated conservation laws. Although the GN equations were developed very recently (compared to other wave theories), they are well-known and fairly understood by the research and scientific community. Ertekin's Ph.D. advisor and dissertation committee chair was Professor Wehausen.
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We derive the ion acoustic wave dispersion relation for a linearized fluid description of a plasma with electrons and N ion species. We write each quantity as X=X_0+\delta\cdot X_1where subscript 0 denotes the "zero-order" constant equilibrium value, and 1 denotes the first-order perturbation. \delta is an ordering parameter for linearization, and has the physical value 1. To linearize, we balance all terms in each equation of the same order in \delta.
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Mlodinow completed his doctorate at the University of California, Berkeley. It was in that PhD dissertation that he developed a new type of perturbation theory for nonrelativistic quantum mechanics, based upon solving the problem in infinite dimensions, and then correcting for the fact that we live in three. The method has become the basis of the 1/d expansion used by theoretical chemists. He has also done pioneering and innovative work in the quantum theory of nonlinear optics.
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On the other hand, if it is brightly coloured like the neighbouring moon Miranda, it would be even smaller than Cupid and comparable to the smallest outer satellites. Mab is heavily perturbed. The actual source for perturbation is still unclear, but is presumed to be one or more of the nearby orbiting moons. Mab orbits at the same distance from Uranus as the μ ring (formerly known as R/2003 U 1), a recently discovered dusty ring.
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They also feature emission indicative of HII regions. The inner ring, which is intrinsically elongated, features a gas cloud formed by the perturbation of a rotating bar at the location where the ring crosses the bar major axis, resulting to star formation. The outer ring features a dimpling near the bar axis, being aligned nearly perpendicular to it. The pseudoring is formed by two faint spiral arms beyond the outer ring that nearly close into another ring.
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His research deals with perturbation methods for dynamical systems and various aspects of theoretical biology, such as neural networks, neuromorphic engineering, disease spreading, and population dynamics. Hoppensteadt was a Christensen Fellow at St Catherine's College, Oxford. He was elected a Fellow of the American Association for the Advancement of Science in 2002. In 1998 he was, with Eugene Izhikevich, an invited speaker with talk Canonical models in mathematical neuroscience at the International Congress of Mathematicians in Berlin.
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A scorpion hides under rocks. A 2009 study also suggests deleterious impacts on animals and ecosystems because of perturbation of polarized light or artificial polarization of light (even during the day, because direction of natural polarization of sun light and its reflection is a source of information for a lot of animals). This form of pollution is named polarized light pollution (PLP). Unnatural polarized light sources can trigger maladaptive behaviors in polarization-sensitive taxa and alter ecological interactions.
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Pressure and Release (PAR) model after Blaikie et al. (1994) showing the progression of vulnerability. The diagram shows a disaster as the intersection between socio- economic pressures on the left and physical exposures (natural hazards) on the right :The PAR model understands a disaster as the intersection between socio- economic pressure and physical exposure. Risk is explicitly defined as a function of the perturbation, stressor, or stress and the vulnerability of the exposed unit (Blaikie et al, 1994).
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Many works of Kato are related to mathematical physics. In 1951, he showed the self-adjointness of Hamiltonians for realistic (singular) potentials. He dealt with nonlinear evolution equations, the Korteweg–de Vries equation (Kato smoothing effect in 1983) and with solutions of the Navier- Stokes equation."Tosio Kato (1917—1999)", Notices of the American Mathematical Society, June/July, 2000 Kato is also known for his influential book Perturbation theory of linear operators, published by Springer-Verlag.
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OpenSim 1.0 was released on August 20, 2007 and provided capabilities for viewing musculoskeletal models, importing models developed in SIMM (Musculographics Inc.), editing muscle paths, and generating muscle actuated simulations that track experimental data. OpenSim 1.1 was released on December 11, 2007, which added new features such as user-specified camera positions for recording movies of simulations, and a perturbation (sensitivity) analysis for inquiry into the function of individual muscles. OpenSim 2.2.1 was released on April 11, 2011.
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Many models beyond the standard model with additional CP-violating terms generically predict a nonzero electric dipole moment and are hence sensitive to such new physics. Instanton corrections from a nonzero θ term in quantum chromodynamics predict a nonzero electric dipole moment for the neutron (it is easier to measure the electric dipole moment in a neutral particle) which have not been observed. This is the strong CP problem and is a prediction of chiral perturbation theory.
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Using current levels of atmospheric carbon dioxide and rates of increase of atmospheric carbon dioxide on a yearly basis based on the time of the article, the lightning-biota climatic feedback once again showed a cooling effect on global average temperatures, given an initial perturbation. Given the simplified nature of the model, several parameters (ozone produced by lightning, etc.) and other feedback mechanisms were neglected, so the significance of the results is still an area of discussion.
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Born in Lusigny-sur- Barse, France, to Jacques‐Hubert Delaunay and Catherine Choiselat, Delaunay studied under Jean-Baptiste Biot at the Sorbonne. He worked on the mechanics of the Moon as a special case of the three-body problem. He published two volumes on the topic, each of 900 pages in length, in 1860 and 1867. The work hints at chaos in the system, and clearly demonstrates the problem of so- called "small denominators" in perturbation theory.
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SCET has also been used to calculate electroweak interactions in Higgs boson production. The new feature of SCET is its ability to handle more than one soft energy scale. For example, processes involving quarks carrying a high energy Q interacting with gluons have two soft scales: the transverse momentum pT of the collinear particles, plus the even softer scale pT2/Q. SCET provides a power-counting formalism for doing perturbation theory in the small parameter ΛQCD/Q.
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The low yield of dimerization reactions is explained by second-order perturbation theory. The LUMO and HOMO of each species are farther apart in energy in a dimerization than in either normally or inversely accelerated Diels–Alder. This means that the orbitals interact less, and there is a lower thermodynamic drive for dimerization. 300px Diels–Alder with inverse electron demand In the dimerization reactions, the diene and dienophile were equally electron rich (or equally electron poor).
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Such disobedience to the States General was, however, not defined as a violation of majestas, but of the exercise of the highest public authority. In sum, in these treason statutes no reference was made to the old laesio majestatis, but to the new concept of "perturbation of the public peace" as the essence of "treason."Damen, pp. 36-40The difference is important, because we will see that in the verdict in the trial against Oldenbarnevelt c.s.
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With French physicists Jacques Bros and Henri Epstein he worked on setting up analyticity properties required for the use of dispersion relations in high energy collisions. Epstein, Glaser and Arthur Jaffe proved that (Wightman) quantum fields can necessarily have negative energy density values. Together with Henri Epstein, he found a new approach to renormalization theory called causal perturbation theory, where ultraviolet divergences are avoided in the calculation of Feynman diagrams by using mathematically well-defined quantities only.
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Diacu's research was focused on qualitative aspects of the n-body problem of celestial mechanics. In the early 1990s he proposed the study of Georgi Manev's gravitational law, given by a small perturbation of Newton's law of universal gravitation, in the general context of (what he called) quasihomogeneous potentials. In several papers, written alone or in collaboration,F. Diacu, Near-Collision Dynamics for Particle Systems with Quasihomogeneous Potentials, Journal of Differential Equations, 128, 58–77, 1996.
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In essence, the authors proposed that the observed network features act in concert as a genetic buffering system to maintain clock function in the face of genetic and environmental perturbation. Following this logic, we may use genomics to explore network features in the circadian oscillator. Another study conducted by Zhang et al. also employed a genome-wide small interfering RNA screen in U2OS cell line to identify additional clock genes and modifiers using luciferase reporter gene expression.
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His work spans a range of different subjects, including string perturbation theory at higher orders, quantum field theories on Riemann surfaces, quantum groups, as well as dualities in string theory and black holes in string theory.Luis Álvarez-Gaumé, Cesar Gomez, Miguel Vázquez-Mozo: Scaling phenomena in Gravity from QCD, Phys. Lett. B649 (2007)478. , Luis Álvarez-Gaumé Scaling Phenomena in gravity and Yang-Mills theories, or black hole formation and its unitarization, Fortschritte der Physik 57 (2010) 327.
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As a result of the controlled change (the perturbation), the system will undergo variations which are measured by a chemical or physical detection method. The measured signals or spectra will show systematic variations that are processed with 2D correlation analysis for interpretation. When one considers spectra that consist of few bands, it is quite obvious to determine which bands are subject to a changing intensity. Such a changing intensity can be caused for example by chemical reactions.
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Molecular dynamics simulations allow scientists to study the time evolution of a chemical system in discrete time intervals. These simulations often utilize molecular mechanics force fields which are generally empirical, parametrized functions which can efficiently calculate the properties and motions of large system., Parametrization is often to a higher level theory or experimental data. MC simulations allow one to explore the potential energy surface of a system by perturbing the system and calculating the energy after the perturbation.
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Shirkov's main works were devoted to quantum field theory, the theory of superconductivity, approximate methods in the theory of slow neutrons, the dynamics of strongly interacting particles at low energies, among many others. He constructed, jointly with Nikolay Bogoliubov, an axiomatic perturbation method for quantum field theory (1954—1958) and developed renormalization group method (1955—1956). He invented and developed the method of quantitative description of elastic and quasi-elastic hadron collisions at low energies (1959—1970).
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The perturbation left by the stimulus moves the stable cycle within the oscillation followed by a return to the stable cycle limit. The curve tracks the amount of advancement or delay due to the input in the oscillating neuron. The PRC assumes certain patterns of behavior in firing pattern as well as the network of oscillating neurons to model the oscillations. Currently, only a few circuits exist which can be modeled using an assumed firing pattern.
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Inclined orbital planes For geostationary spacecraft, thruster burns orthogonal to the orbital plane must be executed to compensate for the effect of the lunar/solar gravitation that perturbs the orbit pole with typically 0.85 degrees per year. The delta-v needed to compensate for this perturbation keeping the inclination to the equatorial plane amounts to in the order 45 m/s per year. This part of the GEO station-keeping is called North-South control.Soop, E. M. (1994).
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Handbook of Geostationary Orbits. Springer. . The East-West control is the control of the orbital period and the eccentricity vector performed by making thruster burns tangential to the orbit. These burns are then designed to keep the orbital period perfectly synchronous with the Earth rotation and to keep the eccentricity sufficiently small. Perturbation of the orbital period results from the imperfect rotational symmetry of the Earth relative the North/South axis, sometimes called the ellipticity of the Earth equator.
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In this region non- perturbative methods, such as Monte-Carlo sampling of the correlation function, are necessary. Lattice perturbation theory can also provide results for condensed matter theory. One can use the lattice to represent the real atomic crystal. In this case the lattice spacing is a real physical value, and not an artifact of the calculation which has to be removed, and a quantum field theory can be formulated and solved on the physical lattice.
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A plasma actuator induces a local flow speed perturbation, which will be developed downstream to a vortex sheet. As a result, plasma actuators can behave as vortex generators. The difference between this and traditional vortex generation is that there are no mechanical moving parts or any drilling holes on aerodynamic surfaces, demonstrating an important benefit of plasma actuators. Three dimensional actuators such as Serpentine geometry plasma actuator generate streamwise oriented vortices,Dasgupta, Arnob, and Subrata Roy.
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Wyld diagrams are bookkeeping graphs that correspond to the Navier–Stokes equations via a perturbation expansion of the fundamental continuum mechanics. Similar to the Feynman diagrams in quantum field theory, these diagrams are an extension of Keldysh's technique for nonequilibrium processes in fluid dynamics. In other words, these diagrams assign graphs to the (often) turbulent phenomena in turbulent fluids by allowing correlated and interacting fluid particles to obey stochastic processes associated to pseudo- random functions in probability distributions.
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Before this epoch, the evolution of the universe could be understood through linear cosmological perturbation theory: that is, all structures could be understood as small deviations from a perfect homogeneous universe. This is computationally relatively easy to study. At this point non-linear structures begin to form, and the computational problem becomes much more difficult, involving, for example, N-body simulations with billions of particles. The Bolshoi Cosmological Simulation is a high precision simulation of this era.
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FHI-aims (Fritz Haber Institute ab initio molecular simulations) is a shared- source software package for computational molecular and materials science written in Fortran. It uses density functional theory and many-body perturbation theory to simulate chemical and physical properties of atoms, molecules, nanostructures, soldis, and surfaces. Originally developed at the Fritz Haber Institute in Berlin the ongoing development of the FHI-aims source code is now driven by a world-wide community of collaborating research institutions.
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Fine and hyperfine structure in hydrogen (not to scale). This section presents a relatively simple and quantitative description of the spin–orbit interaction for an electron bound to a hydrogen-like atom, up to first order in perturbation theory, using some semiclassical electrodynamics and non- relativistic quantum mechanics. This gives results that agree reasonably well with observations. A rigorous calculation of the same result would use relativistic quantum mechanics, using Dirac equation, and would include many- body interactions.
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Aram Arutyunov () (born 1953) is a Russian mathematician, Professor, Dr.Sc., a professor at the Faculty of Computer Science at the Moscow State University and the Peoples' Friendship University of Russia.MSU CMC He defended the thesis «Perturbation of optimal control problems and necessary conditions for the extremum of the first and second order» for the degree of Doctor of Physical and Mathematical Sciences (1988). Was awarded the title of Professor (1991). Author of 7 books and 318 scientific articles.
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The traffic load near large cities may show dramatic cyclical changes induced by weekend tourism, and this could induce cyclical changes in the activity patterns of birds. Road implantation may also lead birds to avoid certain sites, as they are seen as being less habitable (because of increases in noise and chemical pollution). Certain bird populations may then become confined into smaller habitable sites, leading to an increase in possibility of extinction caused by illness or habitat perturbation.
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The linear stability of low viscosity liquids was first derived by Plateau in 1873. However, his solution has become known as the Rayleigh- Plateau instability due to the extension of the theory by Lord Rayleigh to include fluids with viscosity. Rayleigh-Plateau instability is often used as an introductory case to hydrodynamic stability as well as perturbation analysis. Plateau considered the stability of a thread of fluid when only inertial and surface tension effects were present.
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In linear algebra, the eigengap of a linear operator is the difference between two successive eigenvalues, where eigenvalues are sorted in ascending order. The Davis-Kahan theorem, named after Chandler Davis and William Kahan, uses the eigengap to show how eigenspaces of an operator change under perturbation. In spectral clustering, the eigengap is often referred to as the spectral gap; although the spectral gap may often be defined in a broader sense than that of the eigengap.
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However, there are techniques for finding approximate solutions. One method, called perturbation theory, uses the analytic result for a simple quantum mechanical model to create a result for a related but more complicated model by (for example) the addition of a weak potential energy. Another method is called "semi-classical equation of motion", which applies to systems for which quantum mechanics produces only small deviations from classical behavior. These deviations can then be computed based on the classical motion.
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At the University of California, Los Angeles (UCLA), he was an associate professor from 1988 to 1990 and was appointed a full professor in 1990 and a distinguished professor in 2009. From the 1980s onwards, he collaborated extensively with Duong H. Phong on the geometry underlying superstring perturbation theory, among other topics in the mathematics of supersymmetry and superstring theory. Another topic of D'Hoker's research is integrable systems. In 1997 he was at the Institute for Advanced Study.
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In light of the scale-free topology of the PIN, Mahmoudabadi et al.Mahmoudabadi G, Rajagopalan K, Getzenberg RH, Hannenhalli S, Rangarajan G, Kulkarni P. Intrinsically disordered proteins and conformational noise: implications in cancer. Cell Cycle 12: 26-31 (2013). set out to elucidate whether perturbation to IDP hub proteins could account for such dramatic changes as state switching in the absence of DNA mutations (changes to the DNA sequence) and whether these changes could be passed onto the progeny.
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There is no official definition of 'cubewano' or 'classical KBO'. However, the terms are normally used to refer to objects free from significant perturbation from Neptune, thereby excluding KBOs in orbital resonance with Neptune (resonant trans-Neptunian objects). The Minor Planet Center (MPC) and the Deep Ecliptic Survey (DES) do not list cubewanos (classical objects) using the same criteria. Many TNOs classified as cubewanos by the MPC are classified as ScatNear (possibly scattered by Neptune) by the DES.
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This means that at any population size below K, the population is producing a surplus yield that is available for harvesting without reducing population size. Density dependence is the regulator process that allows the population to return to equilibrium after a perturbation. The logistic equation assumes that density dependence takes the form of negative feedback. If a constant number of individuals is harvested from a population at a level greater than the MSY, the population will decline to extinction.
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He was involved in the development of operator form of perturbation theory, approximate second quantization, adiabatic approximation for systems with translational invariance, and other theoretical physics methods which play an important role in the theory of many-particle systems. Since 1948 in collaboration with Nikolay Bogoliubov he started to work on quantum theory of ferromagnetism and antiferromagnetism. In 1948 they developed a consistent theoretical polar model of metals. Later Tyablikov developed the first consistent quantum theory of magnetic anisotropy.
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Firefly, formerly named PC GAMESS, is an ab initio computational chemistry program for Intel-compatible x86, x86-64 processors based on GAMESS (US) sources. However, it has been mostly rewritten (60-70% of the code), especially in platform-specific parts (memory allocation, disk input/output, network), mathematic functions (e.g., matrix operations), and quantum chemistry methods (such as Hartree–Fock method, Møller–Plesset perturbation theory, and density functional theory). Thus, it is significantly faster than the original GAMESS.
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The historical perturbation hypothesis proposes the low species richness of higher latitudes is a consequence of an insufficient time period available for species to colonize or recolonize areas because of historical perturbations such as glaciation (Brown and Lomolino 1998, Gaston and Blackburn 2000). This hypothesis suggests that diversity in the temperate regions has not yet reached equilibrium and that the number of species in temperate areas will continue to increase until saturated (Clarke and Crame 2003).
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Being explicitly based on the Hilbert space language, the KvN classical mechanics adopts many techniques from quantum mechanics, for example, perturbation and diagram techniques as well as functional integral methods. The KvN approach is very general, and it has been extended to dissipative systems, relativistic mechanics, and classical field theories. The KvN approach is fruitful in studies on the quantum-classical correspondence as it reveals that the Hilbert space formulation is not exclusively quantum mechanical.Bracken, A. J. (2003).
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In fact the coupling apparently becomes infinite at some finite energy. This phenomenon was first noted by Lev Landau, and is called the Landau pole. However, one cannot expect the perturbative beta function to give accurate results at strong coupling, and so it is likely that the Landau pole is an artifact of applying perturbation theory in a situation where it is no longer valid. The true scaling behaviour of \alpha at large energies is not known.
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Robustness of a biological system (also called biological or genetic robustness) is the persistence of a certain characteristic or trait in a system under perturbations or conditions of uncertainty. Robustness in development is known as canalization. According to the kind of perturbation involved, robustness can be classified as mutational, environmental, recombinational, or behavioral robustness etc. Robustness is achieved through the combination of many genetic and molecular mechanisms and can evolve by either direct or indirect selection.
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Resilience is the tendency of a system to retain its functional and organizational structure and the ability to recover after a perturbation or disturbance. Resilience also expresses the need for persistence although from a management approach it is expressed to have a broad range of choices and events are to be looked at as uniformly distributed. Elasticity and amplitude are measures of resilience. Elasticity is the speed with which a system returns to its original / previous state.
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Application of more advanced summation methods yielded the exponent in the asymptotic behavior , a value close to unity. The hypothesis for the asymptotic behavior of was recently presented analytically for theory and QED. Together with positiveness of , obtained by summation of the series, it suggests case (b) of the above Bogoliubov and Shirkov classification, and hence the absence of the Landau pole in these theories, assuming perturbation theory is valid (but see above discussion in the introduction ).
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One of them is used as the transmitter, and the other as the receiver. They are connected in a configuration where the transmitter drives the receiver in such a way that identical synchronization of chaos between the two oscillators is achieved. For the purpose of transmission of information, at the transmitter, a message is added as a small perturbation to the chaotic signal that drives the receiver. In this way, the message transmitted is masked by the chaotic signal.
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File:Unitary roughness structure versus hierarchical structure.jpg M. Nosonovsky and B. Bhushan studied the effect of unitary (non-hierarchical) structures of micro and nano roughness, and hierarchical structures (micro roughness covered with nano roughness). They found that hierarchical structure was not only necessary for a high contact angle but essential for the stability of the water-solid and water-air interfaces (the composite interface). Due to an external perturbation, a standing capillary wave can form at the liquid–air interface.
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Furthermore, RBM10 perturbation (knockdown or overexpression) brings about splicing alterations in multiple splicing regulators, including RBM5, and also significantly influences the expression of other splicing regulators, including RBM10 itself. In addition, RBM10 primary transcripts are subjected to alternative splicing at several exons by unidentified splicing regulators, leading to the generation of multiple RBM10 isoforms. These data suggest the existence of an alternative splicing network formed by RBM5, RBM6, and RBM10, as well as other splicing regulators.
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There have been a couple non-linear theories of motion (regarding waves). One put forth uses a perturbation method to expand the description all the way to the third order, and better solutions have been found since then. As for wave deformation, methods much like the boundary integral method and the Boussinesq model have been created. It has been found that high-frequency detail present in a breaking wave plays a part in crest deformation and destabilization.
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The Heisenberg picture is closest to classical Hamiltonian mechanics (for example, the commutators appearing in the above equations directly correspond to classical Poisson brackets). The Schrödinger picture, the preferred formulation in introductory texts, is easy to visualize in terms of Hilbert space rotations of state vectors, although it lacks natural generalization to Lorentz invariant systems. The Dirac picture is most useful in nonstationary and covariant perturbation theory, so it is suited to quantum field theory and many-body physics.
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Like many of the known natural antibiotics, kasugamycin inhibits proliferation of bacteria by tampering with their ability to make new proteins, the ribosome being the major target. Kasugamycin inhibits protein synthesis at the step of translation initiation. Kasugamycin inhibition is thought to occur by direct competition with initiator transfer RNA. Recent experiments suggest that kasugamycin indirectly induces dissociation of P-site-bound fMet-tRNAfMet from 30S subunits through perturbation of the mRNA, thereby interfering with translation initiation.
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The narrow escape problem is a ubiquitous problem in biology, biophysics and cellular biology which has the following formulation: a Brownian particle (ion, molecule, or protein) is confined to a bounded domain (a compartment or a cell) by a reflecting boundary, except for a small window through which it can escape. The narrow escape problem is that of calculating the mean escape time. This time diverges as the window shrinks, thus rendering the calculation a singular perturbation problem.
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The bypass transition scenario was first observed experimentally by P. S. Klebanoff, during his experiments in elevated free-stream turbulence flow. Klebanoff identified an important aspect of the bypass transition. In an experiment using hot wires, he studied flow over a flat plate that was subjected to a 0.3% free-stream turbulence level. At this moderate free-stream turbulence level, he observed a velocity perturbation signal with a frequency under 12Hz, much smaller than the usual Tollmien-Schlichting wave frequency.
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Validity of several theories for periodic water waves, according to Le Méhauté (1976). The light-blue area gives the range of validity of cnoidal wave theory; light-yellow for Airy wave theory; and the dashed blue lines demarcate between the required order in Stokes's wave theory. The light-gray shading gives the range extension by numerical approximations using fifth-order stream-function theory, for high waves (H > ¼ Hbreaking). Stokes's wave theory, when using a low order of the perturbation expansion (e.g.
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Predictions are usually made using calculational approximation methods, although such perturbation theory is inadequate to model some experimental observations (for instance bound states and solitons). Still, physicists widely accept the Standard Model as science's most experimentally confirmed theory. Beyond the Standard Model, some theorists work to unite the electroweak and strong interactions within a Grand Unified Theory (GUT). Some attempts at GUTs hypothesize "shadow" particles, such that every known matter particle associates with an undiscovered force particle, and vice versa, altogether supersymmetry (SUSY).
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A visualization of the cone in Fourier domain. In MRI, the local field \delta B induced by non-ferromagnetic biomaterial susceptibility along the main polarization B₀ field is the convolution of the volume susceptibility distribution \chi with the dipole kernel d: \delta B = d \otimes \chi. This spatial convolution can be expressed as a point-wise multiplication in Fourier domain: \Delta B = D \cdot \Chi. This Fourier expression provides an efficient way to predict the field perturbation when the susceptibility distribution is known.
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All of those are special or partial objects. The object most accurately is the universe of discourse to which the partial or special object belongs. For instance, a perturbation of Pluto's orbit is a sign about Pluto but ultimately not only about Pluto. An object either (i) is immediate to a sign and is the object as represented in the sign or (ii) is a dynamic object, the object as it really is, on which the immediate object is founded "as on bedrock".
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In applied mathematics, Basin-hopping is a global optimization technique that iterates by performing random perturbation of coordinates, performing local optimization, and accepting or rejecting new coordinates based on a minimized function value. The algorithm was described in 1997 by David J. Wales and Jonathan Doye. It is a particularly useful algorithm for global optimization in very high-dimensional landscapes, such as finding the minimum energy structure for molecules. Inspired from Monte-Carlo Minimization first suggested by Li and Scheraga.
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Scientists and engineers are able to use liquid crystals in a variety of applications because external perturbation can cause significant changes in the macroscopic properties of the liquid crystal system. Both electric and magnetic fields can be used to induce these changes. The magnitude of the fields, as well as the speed at which the molecules align are important characteristics industry deals with. Special surface treatments can be used in liquid crystal devices to force specific orientations of the director.
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As a young professor in 1972, Kleinert visited Caltech and was impressed by noted US physicist Richard Feynman. Later, Kleinert was to collaborate with Feynman in some of the latter's last work. This collaboration led to a mathematical method for converting divergent weak-coupling power series into convergent strong- coupling ones. This so-called variational perturbation theory yields at present the most accurate theory of critical exponents Kleinert, H., "Critical exponents from seven-loop strong-coupling φ4 theory in three dimensions".
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In complex dynamics, the bifurcation locus of a family of holomorphic functions informally is a locus of those maps for which the dynamical behavior changes drastically under a small perturbation of the parameter. Thus the bifurcation locus can be thought of as an analog of the Julia set in parameter space. Without doubt, the most famous example of a bifurcation locus is the boundary of the Mandelbrot set. Parameters in the complement of the bifurcation locus are called J-stable.
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At this time Goettingen was the leading center of fast reaction kinetics and relaxation chemistry. Many new approaches for observation and perturbation as well as techniques or instruments adapted to special applications were first developed here. Traueranzeige der Max-Planck-Gesellschaft, 28. Juni 2014 In 1963 De Maeyer was visiting lecturer at Cornell University (Ithaca), in 1966, 1969 and 1972 at University of Colorado Boulder. In 1965 De Maeyer became a Wissenschaftliches Mitglied (Scientific Fellow) of the Max-Planck- Gesellschaft.
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As with the idealized environment, crosswise vorticity lines are tilted into the vertical on the flanks of this updraft. Once the pressure perturbations initiate new updrafts on the flanks and they begin to rotate as a result of stretching and ingestion of newly experienced streamwise vorticity. The right split, having propagated even farther right to the hodograph, has increased the magnitude of positive SRH ingestion. This will serve to increase the rotation in the updraft, intensifying the pressure perturbation, strengthening the storm.
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The fine structure energy corrections can be obtained by using perturbation theory. To perform this calculation one must add the three corrective terms to the Hamiltonian: the leading order relativistic correction to the kinetic energy, the correction due to the spin-orbit coupling, and the Darwin term coming from the quantum fluctuating motion or zitterbewegung of the electron. These corrections can also be obtained from the non-relativistic limit of the Dirac equation, since Dirac's theory naturally incorporates relativity and spin interactions.
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Omics based methods use omics technologies, such as reverse genetics and genomics, transcriptomics, and proteomics, to identify the potential targets of the compound of interest. Reverse genetics and genomics approaches, for instance, uses genetic perturbation (e.g. CRISPR- Cas9 or siRNA) in combination with the compound to identify genes whose knockdown or knockout abolishes the pharmacological effect of the compound. On the other hand, transcriptomics and proteomics profiles of the compound can be used to compare with profiles of compounds with known targets.
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It is then compared to the computed tomographic fan- beam measurement of the absorbing perturbations in the slice. These perturbation data are then reconstructed into slice images using a highly modified proprietary filtered back-projection algorithm that converts the fan- beam data into sinographics. It also corrects for geometric distortions due to bulk light-tissue interaction, and compensates for a spatially variant blurring effect that is typical of diffuse optical imaging. 3D images visualization is available immediately after data acquisition.
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Other 'kinetic perturbation' techniques for studying the folding transition state have appeared recently. Best known is the psi (\psi) value which is found by engineering two metal- binding amino acid residues like histidine into a protein and then recording the folding kinetics as a function of metal ion concentration, though Fersht thought this approach difficult. A 'cross-linking' variant of the \phi-value was used to study segment association in a folding transition state as covalent crosslinks like disulfide bonds were introduced.
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General stability of a population is a measure that assumes stability is higher if there is less of a chance of extinction. This kind of stability is generally measured by measuring the variability of aggregate community properties, like total biomass, over time. The other definition of stability is a measure of resilience and resistance, where an ecosystem that returns quickly to an equilibrium after a perturbation or resists invasion is thought of as more stable than one that does not.
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The change in cross-sectional properties in turn affects the stiffness and mass distribution. Considering the geometric discontinuity along with the perturbation of modes and natural frequencies, the initial homogeneous differential equation with nonconstant coefficients is changed to a series of non-homogeneous differential equations with constant coefficients. Solutions of this series of differential equations is obtained in this framework. This framework is about using structural-dynamics based methods to address the existing challenges in the field of structural health monitoring (SHM).
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He showed that the instantaneous method can be used to characterize the asymptotic behaviour of perturbation theory, thus allowing accurate theoretical estimates to be made (E.Brezin, Fields, strings and critical phenomena, North Holland, Les Houches, 1988). He has applied field theory techniques to condensed matter problems, such as critical wetting theory or the study of the phase transition from a normal metal to a type II superconductor under magnetic field. He became interested in theories of gauging with a large number of colors.
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Such degenerate states are often the case of atomic and molecular valence states. To counter the restrictions, there was an attempt to implement second-order perturbation theory in conjunction with complete active space self-consistent field (CASSCF) wave functions. At the time, it was rather difficult to compute three- and four-particle density matrices which are needed for matrix elements involving internal and semi- internal excitations. The results was rather disappointing with little or no improvement from usual CASSCF results.
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The existence of such a fixed point is relevant, as it grants, at this order of perturbation theory, that conformal invariance is not lost due to quantum corrections, so that the quantum field theory of this model is sensible (renormalizable). Further adding nonlinear interactions representing flavor-chiral anomalies results in the Wess–Zumino–Witten model, which augments the geometry of the flow to include torsion, preserving renormalizability and leading to an infrared fixed point as well, on account of teleparallelism ("geometrostasis").
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He studied theoretical physics as an undergraduate at Harvard University (enrolled 1982 when 16 years old), taking graduate courses as a sophomore when he was 17 years old. He then went straight into Harvard's graduate program and obtained his Ph.D. in 1990 under the supervision of David Robert Nelson. Seung's 1990 doctoral dissertation is titled "Physics of Lines and Surfaces." It examines the statistical mechanics of vortex lines in high-temperature superconductors and uses tools such as the renormalization group perturbation theory.
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The discretized equations are solved numerically on a staggered grid, i.e. the scalar quantities \rho, p and \theta are defined at the cell centre while the velocity components u, v and w are defined at the centre of the appropriate interfaces. Temporal discretization of the prognostic equations is based on the explicit second order Adams- Bashforth scheme. There are two deviations from the Adams-Bashforth scheme: The first refers to the implicit treatment of the nonhydrostatic part of the mesoscale pressure perturbation p_.
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According to the experience gained so far with the model MEMO, neglecting large scale environmental information might result in instabilities in case of simulations over longer time periods. For the nonhydrostatic part of the mesoscale pressure perturbation, homogeneous Neumann boundary conditions are used at lateral boundaries. With these conditions, the wind velocity component perpendicular to the boundary remains unaffected by the pressure change. At the upper boundary, Neumann boundary conditions are imposed for the horizontal velocity components and the potential temperature.
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Following research done by several groups of scientists, perturbation based 2D spectroscopy could be developed to a more extended and generalized broader base. Since the development of generalized 2D correlation analysis in 1993 based on Fourier transformation of the data, 2D correlation analysis gained widespread use. Alternative techniques that were simpler to calculate, for example the disrelation spectrum, were also developed simultaneously. Because of its computational efficiency and simplicity, the Hilbert transform is nowadays used for the calculation of the 2D spectra.
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Soft-field tomography refers to a set of imaging modalities such as electrical capacitance tomography (ECT), electrical impedance tomography (EIT), electrical resistivity tomography (ERT), etc., wherein electric (or magnetic) field lines undergo changes in the presence of a perturbation in the medium. This is in contrast to hard-field tomography, such as X-ray CT, where the electric field lines do not change in the presence of a test subject. A fundamental characteristic of soft-field tomography is its ill-posedness.
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If the perturbation to the oscillatory cycle is infinitesimally small, it is possible to derive a response function of the neural oscillator. This response function can be classified into different classes (Type 1 and Type 2) based upon its response. #Type I Phase Response Curves are non-negative and strictly positive thus perturbations are only able to enhance a spike in phase, but never delay it. This occurs through a slight depolarization, such as postsynaptic potentials that increase the excitation of an axon.
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In lattice perturbation theory the scattering matrix is expanded in powers of the lattice spacing, a. The results are used primarily to renormalize Lattice QCD Monte- Carlo calculations. In perturbative calculations both the operators of the action and the propagators are calculated on the lattice and expanded in powers of a. When renormalizing a calculation, the coefficients of the expansion need to be matched with a common continuum scheme, such as the MS- bar scheme, otherwise the results cannot be compared.
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While Dancoff was at Berkeley, Oppenheimer suggested that he work on the calculation of the scattering of a relativistic electron by an electric field. Such QED calculations typically gave infinite answers. Following earlier perturbation-theory work by Oppenheimer and Felix Bloch, he found that he could deal in various ways with the infinities that arose, sometimes by canceling a positive infinity with a negative one. However, some infinities remained uncanceled and the method (later called renormalization) did not give finite results.
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Accelerating environmental change and continuing loss of genetic resources positions lower biodiversity around the planet threatening ecosystem services. A major mitigating factor will be life forms with higher resilience. Paralleling the work in mountain environments, a growing number of studies is applying the concept of bioresilience to assess the robustness of life in other ecological systems challenged by the Anthropocene. One such study was with the adaptive renewal and natural perturbation in Lake Victoria, the world's second largest freshwater lake.
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Effective-one-body (EOB) solves the dynamics of the binary black hole system by transforming the equations to those of a single object. This is especially useful where mass ratios are large, such as a stellar mass black hole merging with a galactic core black hole, but can also be used for equal mass systems. For the ringdown, black hole perturbation theory can be used. The final Kerr black hole is distorted, and the spectrum of frequencies it produces can be calculated.
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Chike Obi (April 17, 1921 – March 13, 2008) was a Nigerian politician, mathematician and professor. The African Mathematics Union suggests that he was the first Nigerian to hold a doctorate in mathematics. Dr. Obi's early research dealt mainly with the question of the existence of periodic solutions of non-linear ordinary differential equations. He successfully used the perturbation technique, and several of his publications greatly helped to stimulate research interest in this subject throughout the world and have become classics in the literature.
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In older adults, physical training and perturbation therapy is directed to improving balance recovery responses and preventing falls. Gait related changes in elderly provide greater chance of stability during walking due to slow speed and greater base of support, but they also increase the chance of slipping or tripping and falling. Appropriate joint moment generation is required to create sufficient push-off for balance recovery. Age-related changes in muscles, tendons, and neural structures may contribute to slower reactive responses.
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This element loses its heat more rapidly than its salinity because the diffusion of heat is faster than of salt; this is analogous to the way in which just unstirred coffee goes cold before the sugar has diffused to the top. Because the water becomes cooler but remains salty, it becomes denser than the fluid layer beneath it. This makes the perturbation grow and causes the downward extension of a salt finger. As this finger grows, additional thermal diffusion accelerates this effect.
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Structure and Interpretation of Classical Mechanics (SICM) is a classical mechanics textbook written by Gerald Jay Sussman and Jack Wisdom with Meinhard E. Mayer. The first edition was published by MIT Press in 2001, and a second edition was released in 2015. The book is used at the Massachusetts Institute of Technology to teach a class in advanced classical mechanics, starting with Lagrange's equations and proceeding through canonical perturbation theory. SICM explains some physical phenomena by showing computer programs for simulating them.
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Chapel Hill: Professional Press. p. 143 Perturbations are said to be precisely encoded information contained in the thought field; each deformation of a person's thought field is connected to a particular problem, and is activated by thinking about that problem. Callahan maintains that these perturbations are the root cause of negative emotions and that each perturbation corresponds to a meridian point on the body. In order to eliminate the emotional upset, Callahan says that a precise sequence of meridian points must be tapped.
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Nikolai Nikolaevich Nekhoroshev (; 2 October 1946 – 18 October 2008) was a prominent Soviet Russian mathematician specializing in classical mechanics and dynamical systems. His research concerned Hamiltonian mechanics, perturbation theory, celestial mechanics, integrable systems, dynamical systems, the quasiclassical approximation, and singularity theory. He proved, in particular, a stability result in KAM-theory stating that, under certain conditions, solutions of nearly integrable systems stay close to invariant tori for exponentially long times . Nekhoroshev was professor of the Moscow State University and University of Milan.
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Depending on the symmetry of the perturbation that is used to write the LPFG, modes of different symmetries may be coupled. For instance, cylindrically symmetric gratings couple symmetric LP0m modes of the fiber. Microbend gratings, which are antisymmetric with respect to the fiber axis, create a resonance between the core mode and the asymmetric LP1m modes of the core and the cladding. Long period grating has a wide variety of applications, including band-rejection filters, gain flattening filter and sensors.
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In September 2008, it was announced that a Jupiter-like planet, now designated as Gliese 832 b, had been detected in a long-period, near-circular orbit around this star (false alarm probability thus far: a negligible 0.05%). It would induce an astrometric perturbation on its star of at least 0.95 milliarcseconds and is thus a good candidate for being detected by astrometric observations. Despite its relatively large angular distance, direct imaging is problematic due to the star–planet contrast.
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There will always be a risk that anonymized data may not stay anonymous over time. Pairing the anonymized dataset with other data, clever techniques and raw power are some of the ways previously anonymous data sets have become de-anonymized; The data subjects are no longer anonymous. De- anonymization is the reverse process in which anonymous data is cross- referenced with other data sources to re-identify the anonymous data source. Generalization and perturbation are the two popular anonymization approaches for relational data.
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It is then possible to minimize the grand potential with respect to the local density, which results in a mean-field expression for local chemical potential. And the theory is completed by specifying the chemical potential for a second (possibly bulk) phase. And in an equilibrium process, μI=μII. Lattice density functional theory has several advantages over more complicated free volume techniques such as Perturbation theory and the statistical associating fluid theory, including mathematical simplicity and ease of incorporating complex boundary conditions.
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Rather than an exact closed form solution, orbits with many bodies can be approximated with arbitrarily high accuracy. These approximations take two forms: :One form takes the pure elliptic motion as a basis, and adds perturbation terms to account for the gravitational influence of multiple bodies. This is convenient for calculating the positions of astronomical bodies. The equations of motion of the moons, planets and other bodies are known with great accuracy, and are used to generate tables for celestial navigation.
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In addition to energy, Galli's research covers problems related to water resources at ambient conditions and in severe environments. Other areas of interest include phenomena and materials used to realize quantum information technologies. Galli's software activities are focused on the development of the WEST code (large-scale electronic structure within many-body perturbation theory) and participation in the development of the Qbox code (ab initio molecular dynamics) led by Francois Gygi at University of California, Davis, both of which are supported by MICCoM.
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A pseudoholomorphic curve satisfying this equation can be called, more specifically, a (j, J, u)-holomorphic curve. The perturbation u is sometimes assumed to be generated by a Hamiltonian (particularly in Floer theory), but in general it need not be. A pseudoholomorphic curve is, by its definition, always parametrized. In applications one is often truly interested in unparametrized curves, meaning embedded (or immersed) two-submanifolds of X, so one mods out by reparametrizations of the domain that preserve the relevant structure.
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In this proposed S-matrix theory, there are no local quantities at all. Heisenberg proposed to use unitarity to determine the S-matrix. In all conceivable situations, the sum of the squares of the amplitudes must equal 1. This property can determine the amplitude in a quantum field theory order by order in a perturbation series once the basic interactions are given, and in many quantum field theories the amplitudes grow too fast at high energies to make a unitary S-matrix.
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In a quantum field theory with a dimensionless coupling g, if g is much less than 1, the theory is said to be weakly coupled. In this case, it is well described by an expansion in powers of g, called perturbation theory. If the coupling constant is of order one or larger, the theory is said to be strongly coupled. An example of the latter is the hadronic theory of strong interactions (which is why it is called strong in the first place).
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In 1998 he won the fellowship of the Royal Society on being nominated by the theoretical physicist Stephen Hawking. His contributions include the entropy function formalism for extremal black holes and its applications to attractors. His recent important works include the attractor mechanism and the precision counting of microstates of black holes, and new developments in string perturbation theory. He joined the National Institute of Science Education and Research (NISER), Bhubaneswar, India as an honorary professor in the School of Physical Sciences.
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This systematic computational procedure is known as renormalization and can be applied to arbitrary order in perturbation theory. By applying the renormalization procedure, calculations were finally made to explain the electron's anomalous magnetic moment (the deviation of the electron g-factor from 2) and vacuum polarisation. These results agreed with experimental measurements to a remarkable degree, thus marking the end of a "war against infinities". At the same time, Feynman introduced the path integral formulation of quantum mechanics and Feynman diagrams.
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Alexei Borisovich Zamolodchikov (; 18 September 1952 – 18 October 2007) was a Russian physicist known for his contributions to quantum field theory, quantum gravity and the Liouville string theory. Today, the application of this technique is a standard way of analyzing 2D quantum field theories beyond perturbation theory. He was the brother of well-known physicist Alexander Zamolodchikov. Born in Novo-Ivankovo (now Dubna), they both earned a B.Sc. in nuclear engineering (1969–76) from Moscow Institute of Physics and Technology.
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In the linear limit the instability causes exponential growth of electromagnetic fields in the plasma which help restore momentum space isotropy. In very extreme cases, the Weibel instability is related to one- or two-dimensional stream instabilities. Consider an electron-ion plasma in which the ions are fixed and the electrons are hotter in the y-direction than in x or z-direction. To see how magnetic field perturbation would grow, suppose a field B = B cos kx spontaneously arises from noise.
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MCEs has same threats with shallow reefs such as water warmer bleaching and storm but less exposure than shallow. Furthermore, by virtue of their depth and their remote offshore location, gives MCEs great protection from direct human impact such as run-off and overfishing. Overexploitation fisheries in shallow areas may lead to perturbation of trophic level in MCEs. In addition bottom landings gear usage can cause physical damage to the reefs and stir up sediment that smothering coral, causing their death.
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Much progress has been made during the past decade, both numerically and experimentally, toward the understanding of the kinematics (dynamics) of VIV, albeit in the low-Reynolds number regime. The fundamental reason for this is that VIV is not a small perturbation superimposed on a mean steady motion. It is an inherently nonlinear, self- governed or self-regulated, multi-degree-of-freedom phenomenon. It presents unsteady flow characteristics manifested by the existence of two unsteady shear layers and large-scale structures.
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PIKfyve mutations affecting one of the two PIKFYVE alleles are found in 8 out of 10 families with Francois- Neetens corneal fleck dystrophy. Disruption of both PIKFYVE alleles in the mouse is lethal at the stage of pre-implantation embryo. PIKfyve’s role in pathogen invasion is deduced by evidence from cell studies implicating PIKfyve activity in HIV and Salmonella replication. A link of PIKfyve with type 2 diabetes is inferred by the observations that PIKfyve perturbation inhibits insulin-regulated glucose uptake.
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SV40 large T antigen (Simian Vacuolating Virus 40 TAg) is a hexamer protein that is a dominant-acting oncoprotein derived from the polyomavirus SV40. TAg is capable of inducing malignant transformation of a variety of cell types. The transforming activity of TAg is due in large part to its perturbation of the retinoblastoma (pRb) and p53 tumor suppressor proteins. In addition, TAg binds to several other cellular factors, including the transcriptional co- activators p300 and CBP, which may contribute to its transformation function.
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Many results for diagonalizable matrices hold only over an algebraically closed field (such as the complex numbers). In this case, diagonalizable matrices are dense in the space of all matrices, which means any defective matrix can be deformed into a diagonalizable matrix by a small perturbation; and the Jordan normal form theorem states that any matrix is uniquely the sum of a diagonalizable matrix and a nilpotent matrix. Over an algebraically closed field, diagonalizable matrices are equivalent to semi-simple matrices.
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Computational ab initio methods used have included CCSD(T), MP2 (Møller–Plesset perturbation theory of the second order), CIS and CISD. For heavy atoms, effective core potentials are used to model the inner electrons, so that their contributions do not have to be individually computed. More powerful computers since the 1990s have made this kind of in silico study much more popular, being much less risky and simpler than an actual experiment. This article is mostly based on experimental or observational results.
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High-throughput synthetic lethal screens may help illuminate questions about how cellular processes work without previous knowledge of gene function or interaction. Screening strategy must take into account the organism used for screening, the mode of genetic perturbation, and whether the screen is forward or reverse. Many of the first synthetic lethal screens were performed in S. cerevisiae. Budding yeast has many experimental advantages in screens, including a small genome, fast doubling time, both haploid and diploid states, and ease of genetic manipulation.
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In 1991, Carlos Lousto was honored with an Alexander von Humboldt Foundation fellowship. In 2006 and in 2016 his research was acknowledged in the US congressional records. In 2012, Carlos Lousto was elected a Fellow of the American Physical Society "For his important contributions at the interface between perturbation theory and numerical relativity and in understanding how to simulate binary black holes". 2016 Special Breakthrough Prize in Fundamental Physics "For the observation of gravitational waves, opening new horizons in astronomy and physics".
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In the Solar System, this is usually the case; Jupiter, the second largest body, has a mass of about 1/1000 that of the Sun. General perturbation methods are preferred for some types of problems, as the source of certain observed motions are readily found. This is not necessarily so for special perturbations; the motions would be predicted with similar accuracy, but no information on the configurations of the perturbing bodies (for instance, an orbital resonance) which caused them would be available.
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Wu received his BSc in 1946 from National Chiao Tung University in Shanghai (now Shanghai Jiao Tong University), and spent one year teaching upon graduation. In January 1948 he arrived in the U.S. and enrolled at Iowa State University and graduated with an MS in December the same year. After Iowa, Wu went to Caltech, where he shared an office with Julian Cole. Wu was involved in the research group headed by Paco Lagerstrom, where they developed further the asymptotic perturbation method pioneered by Ludwig Prandtl.
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According to the ETAS model, the rate of triggered activity around a given event behaves isotropically. This over-simplified assumption has recently relaxed by coupling the statistics of ETAS to genuine mechanical information. This is done by modelling the stress perturbation due to a given event on its surroundings, and correlating it with the space-time rate of subsequent activity as a function of transferred stress amplitude and sign. This suggests that triggering of aftershocks stems from a combination of dynamic (seismic waves) and elasto-static processes.
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The orbital tilt carries this star as much as from the galactic plane. Based upon high resolution measurements performed at the W. M. Keck Observatory and analysis performed upon these measurements by amateur astronomer Peter Jalowiczor, HD 218566 shows cyclical variations in radial velocity that suggest gravitational perturbation by orbiting companion. This candidate object is estimated to be orbiting the parent star with a period of days at an eccentricity of . The semi-major axis for this Keplerian orbit is an estimated 0.6873 Astronomical Units.
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Scientists have also devised a large number of nanowire compositions with controlled length, diameter, doping, and surface structure by using vapor and solution phase strategies. These oriented single crystals are being used in semiconductor nanowire devices such as diodes, transistors, logic circuits, lasers and sensors. Since nanowires have one dimensional structure meaning large surface to volume ratio, the diffusion resistance decreases. In addition, their efficiency in electron transport which is due to the quantum confinement effect, make their electrical properties be influenced by minor perturbation.
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This suggests a requirement for 2d to be present in order to induce the proper formation of the head along a dorsal-ventral axis. When micromeres 2d1 and 2d2, the immediate descendants of 2d, are both deleted, the resulting larvae retain dorsal-ventral organization within the head. It was therefore concluded that in C. teleta micromere 2d has organizing activity in patterning the dorsal- ventral body axis. Furthermore, perturbation studies have shown that the dorsal-ventral axis is primarily patterned via the Activin/Nodal pathway.
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Herzberg himself emphasized the importance of this in his Nobel Prize lecture. Kołos established a strong research group in molecular quantum chemistry in Warsaw, and made many other important contributions, particularly in the field of intermolecular forces. He made important contributions to the development of the symmetry-adapted perturbation theory of intermolecular forces and carried out pioneering studies on the nonadditivity of intermolecular forces. He was a member of the Polish Academy of Sciences, the International Academy of Quantum Molecular Science and the Academia Europaea.
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Shuja-ud-Din's masouleum at Roshnibagh Shuja-ud-Din's tomb A great perturbation was caused in 1739 by the approach of Nader Shah. Shuja ud- Din fell ill and fearing his death he sent Durdan Begum and his son to Odisha. He also appointed Sarfaraz Khan as his heir and successor. He also enjoined Sarfaraz Khan to regard Haji Ahmed, Alam Chand (Roy Royan Alam Chand) and Jagat Seth as his steadfast counsellor and was to follow their advice in all affairs of moment.
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When describing graviton interactions, the classical theory of Feynman diagrams and semiclassical corrections such as one-loop diagrams behave normally. However, Feynman diagrams with at least two loops lead to ultraviolet divergences. These infinite results cannot be removed because quantized general relativity is not perturbatively renormalizable, unlike quantum electrodynamics and models such as the Yang–Mills theory. Therefore, incalculable answers are found from the perturbation method by which physicists calculate the probability of a particle to emit or absorb gravitons, and the theory loses predictive veracity.
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The liquid will then tend towards an equilibrium, where its temperature is the same as its surroundings. (Once there, the liquid is perfectly uniform: to an observer it would appear the same from any position. This equilibrium is also asymptotically stable: after a local, temporary perturbation of the outside temperature, it will go back to its uniform state, in line with the second law of thermodynamics). Then, the temperature of the bottom plane is increased slightly yielding a flow of thermal energy conducted through the liquid.
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Much of the Dutch right wing (including figures such as Geert Wilders) has evolved to include LGBT rights platforms which do not conflict with the current status quo but also embrace an increased perturbation to supposed threats from minority religions (especially Islam) which, in their view, threaten to upend the vestiges of the liberalism and tolerance which has been associated with the Dutch social climate. The former political party the Pim Fortuyn List supported LGBT rights, and its leader and namesake Pim Fortuyn was openly gay.
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The most updated k2 obtained by Genova's team is 0.1697 ± 0.0009. As if k2 is smaller than 0.10 a solid core would be indicated, this tells that at least the outer core is liquid on Mars, and the predicted core radius is 1520–1840 km. However, current radio tracking data from MGS, ODY and MRO does not allow the effect of phase lag on the tides to be detected because it is too weak and needs more precise measurement on the perturbation of spacecraft in the future.
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Bardeen is co-inventor of the theory of the axial vector current anomaly which is of foundational importance in modern theoretical physics. He developed with Stephen L. Adler the "non- renormalization theorem" (known as the Adler–Bardeen theorem). He has played a major role in the development of perturbation theory for quantum chromodynamics, and dynamical approaches to electroweak symmetry breaking.William A. Bardeen, homepage at Fermilab Bardeen is considered one of the leading authorities on quantum field theory and its application to the phenomena of elementary particle physics.
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Furthermore, functional classification lncRNAs remains hotly debated - it is unknown if lncRNAs can be grouped based on common function/mechanisms of action, or by active domains. FANTOM has laid out a three pronged experimental strategy to explore these unknowns. A reference transcriptome and epigenome profile of different cell types will be constructed as a base line for each cell type. Next, using lncRNAs identified in previous publications, FANTOM5 data and further CAGE profiling, perturbation experiments will be conducted to evaluate changes in cellular molecular phenotype.
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The slight increase over a dipole's 2.15 dBi (0 dBd) gain represents the small contribution to the pattern made by the current imbalance on the matching section. The pattern in the E plane reveals a slight elevation of the pattern in the direction of the J element while the pattern opposite the J element is mostly broadside. The net effect of the perturbation caused by quarter-wave stub is an H-plane approximate gain from 1.5 to 2.6 dBi (-0.6 dBd to 0.5 dBd).
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The strongest form of synthetic rescues, in which the deleterious impact of a gene knockout is mitigated by an additional genetic perturbation that is also deleterious when considered in isolation, was modeled and predicted theoretically for gene interactions mediated by the metabolic network. This strong form of synthetic rescue has been recently observed in experiments in both Saccharomyces cerevisiaePartow S. H., Hyland P. B., and Mahadevan K., Synthetic rescue couples NADPH generation to metabolite overproduction in Saccharomyces cerevisiae, Metab. Eng. 43, 64 (2017). and Escherichia coli.
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In 1983, throughout the Caribbean faunal zone as far south as South America and north to the Bahamas, Diadema antillarum underwent mass mortality, with more than 97% of the urchins dying. Since this time some Caribbean reefs have been overgrown by foliose macroalgae. This inhibits coral growth and has further compounded the ongoing decline of scleractinian corals. It also has an overall negative effect on coral reef resilience, which encompasses the ability of a system to resist and recover from changes stemming from perturbation events.
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In 2005, he obtained Young Faculty Award and Scholarship from the Foundation for the Advancement of Outstanding Scholarship. In 2006, he became one of four awardees of the American Chemical Society Outstanding Junior Faculty Award, in 2010, he received the Distinguished Young Chemist Award from the Chinese Chemical Society, and in 2014, he was awarded the APATCC Pople Medal "for his innovative contributions to theoretical and mathematical aspects of quantum chemistry, particularly his contributions to multireference perturbation theory and the density-functional tight-binding method.".
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This is a single-lined spectroscopic binary system, which means that the two stellar components have not been individually resolved with a telescope. Instead, their orbital motion can be tracked through periodic shifts in the spectrum of the primary. The gravitational perturbation of the hidden secondary component upon the primary is causing the latter to first move toward and then away from the Earth, creating Doppler shift changes in the spectrum. From these subtle shifts, the orbital elements of the pair can be extracted.
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MPQC (Massively Parallel Quantum Chemistry) is an ab initio computational chemistry software program. Three features distinguish it from other quantum chemistry programs such as Gaussian and GAMESS: it is open-source, has an object-oriented design, and is created from the beginning as a parallel processing program. It is available in Ubuntu and Debian. MPQC provides implementations for a number of important methods for calculating electronic structure, including Hartree-Fock, Møller-Plesset perturbation theory (including its explicitly correlated linear R12 versions), and density functional theory.
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Transcriptional repression via steric hindrance CRISPR interference (CRISPRi) is a genetic perturbation technique that allows for sequence-specific repression of gene expression in prokaryotic and eukaryotic cells. It was first developed by Stanley Qi and colleagues in the laboratories of Wendell Lim, Adam Arkin, Jonathan Weissman, and Jennifer Doudna. Sequence-specific activation of gene expression refers to CRISPR activation (CRISPRa). Based on the bacterial genetic immune system - CRISPR (clustered regularly interspaced short palindromic repeats) pathway, the technique provides a complementary approach to RNA interference.
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Current research for the EGC is focused on freshwater fluxes. Because the EGC runs through the Greenland Sea and eventually through the Labrador Sea (as the West Greenland Current) it can have strong implications for the strengthening and or weakening of deep water formations in the Greenland and Labrador Seas. The Meridional Overturning Circulation is a density driven circulation in which a small perturbation in the density field could easily slow down or speed up the deep water formation in the Nordic Seas. Jones et al.
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Convergence can be slow, rapid, oscillatory, regular, highly erratic or simply non-existent, depending on the precise chemical system or basis set. The density matrix for the first-order and higher MP2 wavefunction is of the type known as response density, which differs from the more usual expectation value density. The eigenvalues of the response density matrix (which are the occupation numbers of the MP2 natural orbitals) can therefore be greater than 2 or negative. Unphysical numbers are a sign of a divergent perturbation expansion.
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In this case the dominant pressure gradient is hydrostatic, resulting from the acceleration. When in the unstable configuration, for a particular harmonic component of the initial perturbation, the torque on the interface creates vorticity that will tend to increase the misalignment of the gradient vectors. This in turn creates additional vorticity, leading to further misalignment. This concept is depicted in the figure, where it is observed that the two counter-rotating vortices have velocity fields that sum at the peak and trough of the perturbed interface.
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In 2016, data collected during the extended K2 mission of the Kepler space telescope was used to identify two transiting exoplanet candidates orbiting this star, designated HD 3167 b and HD 3167 c. This makes it one of the closest and brightest such multi-transiting stars known. The lack of chromospheric activity makes it ideal for the precise radial velocity (RV) measurements needed to estimate the masses of its planets. Follow-up RV observations showed additional perturbation signals beyond the two planets already identified.
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In physics and other fields of science, one frequently comes across problems of an asymptotic nature, such as damping, orbiting, stabilization of a perturbed motion, etc. Their solutions lend themselves to asymptotic analysis (perturbation theory), which is widely used in modern applied mathematics, mechanics and physics. But asymptotic methods put a claim on being more than a part of classical mathematics. K. Friedrichs said: “Asymptotic description is not only a convenient tool in the mathematical analysis of nature, it has some more fundamental significance”.
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Significant efforts in computational systems biology of cancer have been made in creating realistic multi-scale in silico models of various tumours. The investigations are frequently combined with large-scale perturbation methods, including gene-based (RNAi, mis-expression of wild type and mutant genes) and chemical approaches using small molecule libraries. Robots and automated sensors enable such large-scale experimentation and data acquisition. These technologies are still emerging and many face problems that the larger the quantity of data produced, the lower the quality.
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In mathematics, the Bauer–Fike theorem is a standard result in the perturbation theory of the eigenvalue of a complex-valued diagonalizable matrix. In its substance, it states an absolute upper bound for the deviation of one perturbed matrix eigenvalue from a properly chosen eigenvalue of the exact matrix. Informally speaking, what it says is that the sensitivity of the eigenvalues is estimated by the condition number of the matrix of eigenvectors. The theorem was proved by Friedrich L. Bauer and C. T. Fike in 1960.
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Materials being emitted from volcanoes typically carry heavy metals in the trace level. When large quantities of these emissions are collected into a small area, the contamination effects become paramount. :The short-term (months-to-years) impacts of volcanism on the atmosphere, climate and environment are strongly controlled by location, timing, flux, magnitude and emission height of sulfur gases. Episodic explosive eruptions represent the principal perturbation to stratospheric aerosol (though the atmospheric effects of sulfur degassing associated with continental flood basalts might well be more profound).
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However, perturbation expansions are generally not reliable for questions of long-term existence and stability, in the case of nonlinear equations. The full field equation is highly nonlinear, so we really want to prove that the Minkowski vacuum is stable under small perturbations which are treated using the fully nonlinear field equation. This requires the introduction of many new ideas. The desired result, sometimes expressed by the slogan that the Minkowski vacuum is nonlinearly stable, was finally proven by Demetrios Christodoulou and Sergiu Klainerman only in 1993.
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1Osculating orbital parameters of irregular satellites of Jupiter change widely in short intervals due to heavy perturbation by Jupiter. For example, changes of as much as 1 Gm in semi-major axis in 2 years, 0.5 in eccentricity in 12 years, and as much as 5° in 24 years have been reported. Mean orbital elements are the averages calculated by the numerical integration of current elements over a long period of time, used to determine the dynamical families. 2With the exception of Kalyke, substantially redder.
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McEwen and Wingfield propose two types of allostatic load with different etiologies and distinct consequences:- > Type 1 allostatic load occurs when energy demand exceeds supply, resulting > in activation of the emergency life history stage. This serves to direct the > animal away from normal life history stages into a survival mode that > decreases allostatic load and regains positive energy balance. The normal > life cycle can be resumed when the perturbation has passed. Typical > situations ending up in type 1 allostasis are starvation, hibernation and > critical illness.
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The nearly free electron model rewrites the Schrödinger equation for the case of a periodic potential. The solutions in this case are known as Bloch states. Since Bloch's theorem applies only to periodic potentials, and since unceasing random movements of atoms in a crystal disrupt periodicity, this use of Bloch's theorem is only an approximation, but it has proven to be a tremendously valuable approximation, without which most solid-state physics analysis would be intractable. Deviations from periodicity are treated by quantum mechanical perturbation theory.
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At some point, perturbation effects will probably cause chaotic variations in the obliquity of the Earth, and the axial tilt may change by angles as high as 90° from the plane of the orbit. This is expected to occur between 1.5 and 4.5 billion years from now. A high obliquity would probably result in dramatic changes in the climate and may destroy the planet's habitability. When the axial tilt of the Earth exceeds 54°, the yearly insolation at the equator is less than that at the poles.
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This promptly lead to the study of "nearly integrable systems", of which the KAM torus is the canonical example. At the same time, it was also discovered that many (rather special) non-linear systems, which were previously approachable only through perturbation theory, are in fact completely integrable. This discovery was quite dramatic, as it allowed exact solutions to be given. This, in turn, helped clarify the meaning of the perturbative series, as one could now compare the results of the series to the exact solutions.
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Interaction in the quantum world: world lines of point-like particles or a world sheet swept up by closed strings in string theory. In quantum field theory, one typically computes the probabilities of various physical events using the techniques of perturbation theory. Developed by Richard Feynman and others in the first half of the twentieth century, perturbative quantum field theory uses special diagrams called Feynman diagrams to organize computations. One imagines that these diagrams depict the paths of point-like particles and their interactions.
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The interaction of strings is most straightforwardly defined by generalizing the perturbation theory used in ordinary quantum field theory. At the level of Feynman diagrams, this means replacing the one-dimensional diagram representing the path of a point particle by a two-dimensional surface representing the motion of a string. Unlike in quantum field theory, string theory does not yet have a full non-perturbative definition, so many of the theoretical questions that physicists would like to answer remain out of reach.Zwiebach 2009, p.
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Using first-order perturbation theory, he successfully explained the phenomenon of spontaneous emission. According to the uncertainty principle in quantum mechanics, quantum harmonic oscillators cannot remain stationary, but they have a non-zero minimum energy and must always be oscillating, even in the lowest energy state (the ground state). Therefore, even in a perfect vacuum, there remains an oscillating electromagnetic field having zero-point energy. It is this quantum fluctuation of electromagnetic fields in the vacuum that "stimulates" the spontaneous emission of radiation by electrons in atoms.
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Evidence for such an extinction includes the disappearance from the fossil record of the Ediacara biota and shelly fossils such as Cloudina, and the accompanying perturbation in the record. It is suspected that several global anoxic events were responsible for the extinction.Did extreme fluctuations in oxygen, not a gradual rise, spark the Cambrian explosion?The Cambrian explosion was caused by a lack of oxygen, not an abundance Mass extinctions are often followed by adaptive radiations as existing clades expand to occupy the ecospace emptied by the extinction.
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1473–77; Anomalous dimensions and breakdown of scale invariance in perturbation theory, ibid. p. 1478–93; ; and the physical meaning of the renormalization group.Wilson, K. G.:Problems in physics with many scales of length, Scientific American, August 1979 He also pioneered the understanding of the confinement of quarks inside hadrons, utilizing lattice gauge theory, and initiating an approach permitting formerly foreboding strong-coupling calculations on computers. On such a lattice, he further shed light on chiral symmetry, a crucial feature of elementary particle interactions.
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The momentum equation for a resistive MHD is linearized and then manipulated into a linear force operator. Due to purely mathematical reasons, it is then possible to split the analysis into two approaches: the normal mode method and the energy method. The normal mode method essentially looks for the eigenmodes and eigenfrequencies and summing the solutions to form the general solution. The energy method is similar to the simpler approach outlined above where is found for any arbitrary perturbation in order to maintain the condition .
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Their track "Sweet Mountain River" was included in Ubisoft's music game Rocksmith 2014, "Seven Seas Blues" in EA Sports' NHL 13, and "Old Train" was used in an episode of Orphan Black, "Variable and Full of Perturbation". The first single from their second studio album was released on October 19, 2015, a track called "Don't Tell Me How to Live". A song, "The Enforcer", was also available only when pre-ordering the album. Their song "Righteous Smoke" is featured in EA Sports' NHL 17.
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When strong laser field perturbs the molecule, its energy levels are no longer the same as in the absence of the field. To calculate the new energy levels, the perturbation must be included as off-diagonal elements of the Hamiltonian, which has to be diagonalised. In consequence, the crossings turn into anticrossings and the higher the laser intensity, the larger the gap of the anticrossing as shown in Fig. 2. The molecule can dissociate along the lower branch of the anticrossings as indicated by the red arrows.
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Together with Ruth Britto, Bo Feng and Edward Witten, he introduced the recursion relations for the computation of scattering amplitudes, which opened a new window for computations required at particle accelerators, such as the Large Hadron Collider. With Nima Arkani-Hamed and collaborators, he studied N = 4 supersymmetric Yang–Mills theory and showed how to compute amplitudes at any order in the perturbation theory. He co- discovered a new formalism unifying gauge theory and gravity in any space-time dimension, known as the Cachazo-He-Yuan formulation.
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The possibility of traveling to another universe is, however, only theoretical since any perturbation would destroy this possibility. It also appears to be possible to follow closed timelike curves (returning to one's own past) around the Kerr singularity, which leads to problems with causality like the grandfather paradox. It is expected that none of these peculiar effects would survive in a proper quantum treatment of rotating and charged black holes. The appearance of singularities in general relativity is commonly perceived as signaling the breakdown of the theory.
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Le Chatelier's principle refers to states of thermodynamic equilibrium. The latter are stable against perturbations that satisfy certain criteria; this is essential to the definition of thermodynamic equilibrium. For this, a state of thermodynamic equilibrium is most conveniently described through a fundamental relation that specifies a cardinal function of state, of the energy kind, or of the entropy kind, as a function of state variables chosen to fit the thermodynamic operations through which a perturbation is to be applied.Münster, A. (1970), pp. 173–174.
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Together with Arnold M. Kosevich, Lifshitz established (1954) connection between the oscillation of magnetic characteristics of metals and the form of an electronic surface of Fermi (Lifshitz–Kosevich formula) from de Haas–van Alphen experiments. Lifshitz was one of the founders of the theory of disordered systems. He introduced some of the basic notions, such as self-averaging, and discovered what is now called Lifshitz tails and Lifshitz singularity. In perturbation theory, Lifshitz introduced the notion of spectral shift function, which was later developed by Mark Krein.
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Mandelstam noted that the limit where the Regge trajectories are straight is also the limit where the lifetime of the states is long. As a fundamental theory of strong interactions at high energies, Regge theory enjoyed a period of interest in the 1960s, but it was largely succeeded by quantum chromodynamics. As a phenomenological theory, it is still an indispensable tool for understanding near-beam line scattering and scattering at very large energies. Modern research focuses both on the connection to perturbation theory and to string theory.
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Two-dimensional infrared correlation spectroscopy analysis combines multiple samples of infrared spectra to reveal more complex properties. By extending the spectral information of a perturbed sample, spectral analysis is simplified and resolution is enhanced. The 2D synchronous and 2D asynchronous spectra represent a graphical overview of the spectral changes due to a perturbation (such as a changing concentration or changing temperature) as well as the relationship between the spectral changes at two different wavenumbers. Pulse Sequence used to obtain a two-dimensional Fourier transform infrared spectrum.
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When \theta > 1 is big, the adversary has more ability to increase the likelihood of hard problem instances. In this perturbation model, the expected number of iterations of the 2-opt heuristic, as well as the approximation ratios of resulting output, are bounded by polynomial functions of n and \theta. Another local search algorithm for which smoothed analysis was successful is Lloyd's algorithm for k-means clustering. Given n points in [0,1]^d, it is NP-hard to find a good partition into clusters with small pairwise distances between points in the same cluster.
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Several different gravitational perturbation algorithms are used to get fairly accurate estimates of the path of objects in the solar system. People often decide to put a satellite in a frozen orbit. The path of a satellite closely orbiting the Earth can be accurately modeled starting from the 2-body elliptical orbit around the center of the Earth, and adding small corrections due to the oblateness of the Earth, gravitational attraction of the Sun and Moon, atmospheric drag, etc. It is possible to find a frozen orbit without calculating the actual path of the satellite.
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Modifications generate conditional effects on proteins, whereby their covalent attachment to amino acids will cause perturbation of a particular protein resulting in an impact on the potential interactions of its newly modified form. Methylation is one of the most recognised post- translational modifications in histones for chromatin structure and gene expression. It is also one of many modifications found on the short N-terminal regions of histones, which assemble to form the histone code, which regulates chromatin assembly and epigenetic gene regulation. Identification of methylation across the interactome is poorly documented.
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For instance, messages containing 'sex appeals' may work well on TV because movement lends itself to eroticism, but may become "flat" in a static medium such as print. In such cases it is important that the secondary media support the primary media and that messages harmonise. Research studies suggest that consumers learn more quickly when exposed to messages via different media. The explanation for this is that slight variations in execution create a slight mental perturbation which grabs attention, and results in more elaborate encoding of the main message argument.
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The narrow escape problemD Holcman, Z Schuss, The narrow escape problem SIAM Review 56 (2), 213-257 (2014) is a ubiquitous problem in biology, biophysics and cellular biology. The mathematical formulation is the following: a Brownian particle (ion, molecule, or protein) is confined to a bounded domain (a compartment or a cell) by a reflecting boundary, except for a small window through which it can escape. The narrow escape problem is that of calculating the mean escape time. This time diverges as the window shrinks, thus rendering the calculation a singular perturbation problem.
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This type of modelling has its origins in the mid 19th century when Sir George Stokes – using a perturbation series approach, now known as the Stokes expansion – obtained approximate solutions for nonlinear wave motion. Stokes's wave theory is of direct practical use for waves on intermediate and deep water. It is used in the design of coastal and offshore structures, in order to determine the wave kinematics (free surface elevation and flow velocities). The wave kinematics are subsequently needed in the design process to determine the wave loads on a structure.
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McEwen and Wingfield propose two types of allostatic load which result in different responses: > Type 1 allostatic overload occurs when energy demand exceeds supply, > resulting in activation of the emergency life history stage. This serves to > direct the animal away from normal life history stages into a survival mode > that decreases allostatic load and regains positive energy balance. The > normal life cycle can be resumed when the perturbation passes. > Type 2 allostatic overload begins when there is sufficient or even excess > energy consumption accompanied by social conflict and other types of social > dysfunction.
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All these forms of synchronization share the property of asymptotic stability. This means that once the synchronized state has been reached, the effect of a small perturbation that destroys synchronization is rapidly damped, and synchronization is recovered again. Mathematically, asymptotic stability is characterized by a positive Lyapunov exponent of the system composed of the two oscillators, which becomes negative when chaotic synchronization is achieved. Some chaotic systems allow even stronger control of chaos, and both synchronization of chaos and control of chaos constitute parts of what's known as "cybernetical physics".
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Ekman's solution has an intrinsic inflectional wind profile that was found to be unstable to long waves corresponding to the organized large vortices scale. The nonlinear theory showed that the growth of these finite perturbation waves modifies the mean flow, eliminating the dynamic inflectional instability energy so that equilibrium is obtained. The modified mean flow corresponds well with observations. This solution for the layer containing the PBL-scale roll wavelength requires a modification of the flux transports to accommodate modeling of the advective motion of the large vortices.
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In compound (alloy) semiconductors, which many thermoelectric materials are, scattering caused by the perturbation of crystal potential due to the random positioning of substituting atom species in a relevant sublattice is known as alloy scattering. This can only happen in ternary or higher alloys as their crystal structure forms by randomly replacing some atoms in one of the sublattices (sublattice) of the crystal structure. Generally, this phenomenon is quite weak but in certain materials or circumstances, it can become dominant effect limiting conductivity. In bulk materials, interface scattering is usually ignored.
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In a more complicate scenario (turbulent flow, rectangular entrance, open end entrance, etc.), there is seldom an easy method to calculate the thermal entrance length. If the flow is laminar, i.e. Reynolds number is equal or less than 2100 to 2300, the thermal entrance length can be within 5 diameters for high Pr and low Pr materials given there is no large perturbation or eddies [1]. For gases and water at higher temperatures, the Prandtl number is close to 1 and the thermal entrance length can vary between 15 and 40 diameters [1].
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Most meteoroids are broken down to sizes of 10−5 g within that timeframe, because of meteoroid-upon-meteoroid collisions. Thus any antimatter meteor must be either extrasolar in origin itself, or broken off from an antimatter comet that is extrasolar in origin. The former are unlikely to exist from observational evidence. Any extrasolar meteoroid would have a hyperbolic orbit, but less than 1% of the observed meteoroids have such, and the process of perturbation of ordinary (terrene) solar objects, by planetary encounters, into hyperbolic trajectories accounts for all of those.
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Both Smale and Thom worked in direct contact with Maurício Peixoto, who developed Peixoto's theorem in the late 1950s. When Smale started to develop the theory of hyperbolic dynamical systems, he hoped that structurally stable systems would be "typical". This would have been consistent with the situation in low dimensions: dimension two for flows and dimension one for diffeomorphisms. However, he soon found examples of vector fields on higher-dimensional manifolds that cannot be made structurally stable by an arbitrarily small perturbation (such examples have been later constructed on manifolds of dimension three).
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Among Rellich's most important mathematical contributions are his work in the perturbation theory of linear operators on Hilbert spaces: he studied the dependence of the spectral family E_\varepsilon(\lambda) of a self-adjoint operator A_\varepsilon on the parameter \varepsilon. Although the origins and applications of the problem are in quantum mechanics, Rellich's approach was completely abstract. Rellich successfully worked on many partial differential equations with degeneracies. For instance, he showed that in the elliptic case, the Monge-Ampère differential equation, while not necessarily uniquely soluble, can have at most two solutions.
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Membrane microheterogeneity is sometimes inferred from the behavior of enzymes, where the enzymatic activity does not appear to be correlated with the average lipid physical state exhibited by the bulk of the membrane. Often, the methods suggest regions with different lipid fluidity, as would be expected of coexisting gel and liquid crystalline phases within the biomembrane. This is also the conclusion of a series of studies where differential effects of perturbation caused by cis and trans fatty acids are interpreted in terms of preferential partitioning of the two liquid crystalline and gel-like domains.
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DART is an algorithm that is applicable and used successfully in Cancer Genomics. The DART algorithm has been shown to be a strong method for estimating the pathway activity and perturbation signature activity in breast and lung cancer gene expression data sets. Imaging traits such as mammography (Mammography is the process of using low-energy X-rays to examine the human breast tissue) plays an important role in cancer tumor diagnosis. Studies have shown that women with increased mammographic density have a higher risk of developing Breast cancer.
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Thus, such a method provides more information about the dynamics and stages of biological events and processes. The method takes advantage of the easily detectable fluorescent proteins fused to a protein of interest, which can then be followed inside a cell using a fluorescence microscope. The cell may then be treated by a perturbation of interest (e.g. a drug, expression of a misfolded protein), and various properties of the fluorescently tagged protein can be assayed using time-lapse microscopy: #Changes of the fluorescence level indicates changes of expression levels (i.e.
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Initial excitement about the 10-dimensional theories, and the string theories that provide their quantum completion, died by the end of the 1980s. There were too many Calabi–Yaus to compactify on, many more than Yau had estimated, as he admitted in December 2005 at the 23rd International Solvay Conference in Physics. None quite gave the standard model, but it seemed as though one could get close with enough effort in many distinct ways. Plus no one understood the theory beyond the regime of applicability of string perturbation theory.
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Since the best-known linear triatomic molecule (CO2) is electronically non-degenerate in its ground state, Renner chose the electronically excited two-fold degenerate Π-state of this well- known molecule as a model for his studies. The products of purely electronic and purely nuclear rovibrational states served as the zeroth-order (no rovibronic coupling) wave functions in Renner's study. The rovibronic coupling acts as a perturbation. Because Renner is the only author of the 1934 paper that first described the effect, it can be called simply the Renner effect.
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Some of his research during this time studied how slips and falls differ across different age groups. In early 2000s, he began studying gait and posture, and how the two are connected to slips and falls. This work led to several articles on the topics of gait and posture. In 2003, he wrote a paper entitled 'Effects of age-related gait changes on the biomechanics of slips and falls', modeling the human responses to slips and falls for the first time and pioneering the slip- perturbation method to study fall accidents during walking.
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The planet orbits the Sun once every 164.8 years at an average distance of . It is named after the Roman god of the sea and has the astronomical symbol ♆, a stylised version of the god Neptune's trident. Neptune is not visible to the unaided eye and is the only planet in the Solar System found by mathematical prediction rather than by empirical observation. Unexpected changes in the orbit of Uranus led Alexis Bouvard to deduce that its orbit was subject to gravitational perturbation by an unknown planet.
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List of Tomalla prize laureates: ;2016 :Kip Thorne ;2013 :Scott Tremaine - for his contribution to gravitational dynamics. ;2009 :Viatcheslav Mukhanov - for his contributions to inflationary cosmology and especially for the determination of the density perturbation spectrum from inflation. :Alexei Starobinsky - for his pioneering contributions to inflationary cosmology and especially for the determination of the spectrum of gravitational waves generated during inflation. ;2008 :Demetrios Christodoulou ;2003 :Jim Peebles ;2000 :Gustav Tammann - for his efforts in measuring the expansion rate of the universe and especially for his pioneering work using Supernovae as standard candles.
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As this rarely produced a positive health benefit, the concept of oral focal infection gradually lost credibility. However, in the 1980s epidemiological studies began to indicate an association between periodontal disease and coronary artery disease, and associations with other serious systemic conditions soon followed. It is now generally accepted that oral bacteria can gain access systemically and cause disease at remote sites, or cause a general perturbation of the immune system leading to disease.Lamont, RJ, Jenkinson, HF: Oral Microbiology at a Glance 2010, Wiley- Blackwell Once again Miller's contributions have been shown to be correct.
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In 2017, he became the full-time faculty (Instructor) at Icahn School of Medicine at Mount Sinai in New York City, New York. Jaiswal studies the critical role of Cu, Zn superoxide dismutase (SOD1), typical for familial ALS, in the impairment of [Ca2+]mito handling and perturbation of Ca2+ homeostasis in SOD1G93A mice and cell culture models of ALS. These finding, reported in Pharmacology and Neuroscience Journal. Jaiswal has also studied molecular mechanisms of Traumatic Brain Injury (TBI) using 2-photon in-vivo imaging and 3-D microscopy at CNRM/NIH-DoD center.
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The NASA Earth Global Reference Atmospheric Model (Earth-GRAM) was developed by the Marshall Space Flight Center to provide a design reference atmosphere that, unlike the standard atmospheres, allows for geographical variability, a wide range of altitudes (surface to orbital altitudes), and different months and times of day. It can also simulate spatial and temporal perturbations in atmospheric parameters due to turbulence and other atmospheric perturbation phenomena. It is available in computer code written in Fortran. The GRAM series also includes atmospheric models for the planets Venus, Mars and Neptune and the Saturnian moon, Titan.
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Molecular phenotyping describes the technique of quantifying pathway reporter genes, i.e. pre-selected genes that are modulated specifically by metabolic and signaling pathways, in order to infer activity of these pathways. In most cases, molecular phenotyping quantifies changes of pathway reporter gene expression to characterize modulation of pathway activities induced by perturbations such as therapeutic agents or stress in a cellular system in vitro. In such contexts, measurements at early time points are often more informative than later observations because they capture the primary response to the perturbation by the cellular system.
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To identify and quantify adrenaline release during stress, beginning in about 1919 Cannon exploited an ingenious experimental setup. He would surgically excise the nerves by supplying the heart of a laboratory animal such as a dog or cat. Then he would subject the animal to a stressor and record the heart rate response. With the nerves to the heart removed, he could deduce that if the heart rate increased in response to the perturbation, then the increase in heart rate must have resulted from the actions of a hormone.
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General chemical structures of phosphotidylethanol, where R1 and R2 are fatty acid chains Phosphatidylethanols (PEth) are a group of phospholipids formed only in the presence of ethanol via the action of phospholipase D (PLD). The lipid accumulates in the brain and competes at agonists sites of lipid-gated ion channels contributing to alcohol intoxication. The chemical similarity of PEth to phosphatidic acid (PA) and phosphatidylinositol 4,5-bisphosphate (PIP2) suggest a likely broad perturbation to lipid signaling, the exact role of PEth as a competitive lipid ligand has not been studied extensively.
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Keldysh L V 1965 Soviet Phys. JETP 2354 He modeled the MPI process as a transition of the electron from the ground state of the atom to the Volkov states (the state of a free electron in the electromagnetic field). In this model, the perturbation of the ground state by the laser field is neglected and the details of atomic structure in determining the ionization probability are not taken into account. The major difficulty with Keldysh's model was its neglect of the effects of Coulomb interaction on the final state of the electron.
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The Periodic Steady-State or PSS analysis directly computed the periodic steady-state response of a circuit. The periodic small-signal analyses use the periodic steady-state solution as a periodically time-varying operating point and linearize the circuit about that operating point and then computes the response of the circuit to small perturbation sources. Effectively they build a periodically time-varying linear model of the circuit. This is significant as periodically time-varying linear models, unlike the time-invariant linear models used by the traditional small-signal analyses (AC and noise) exhibit frequency conversion.
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In physics, an oscillon is a soliton-like phenomenon that occurs in granular and other dissipative media. Oscillons in granular media result from vertically vibrating a plate with a layer of uniform particles placed freely on top. When the sinusoidal vibrations are of the correct amplitude and frequency and the layer of sufficient thickness, a localized wave, referred to as an oscillon, can be formed by locally disturbing the particles. This meta- stable state will remain for a long time (many hundreds of thousands of oscillations) in the absence of further perturbation.
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This resulted in what is now known as the Eckhaus instability criterion and Eckhaus instability, appearing for instance as a secondary instability in models of Rayleigh–Bénard convection. Later, Eckhaus worked on singular perturbation theory and soliton equations. In 1983 he treated strongly singular relaxation oscillations – called "canards" (French for "ducks") – resulting in his most-read paper "Relaxation oscillations including a standard chase on French ducks". Eckhaus used standard methods of analysis, on a problem qualified before, by Marc Diener, as an example of a problem only treatable through the use of non-standard analysis.
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Transitions from a HS to a LS state cause a decrease in and a strengthening of the metal-ligand bond. These changes are also manifested in FT-IR and Raman spectra. The spin crossover phenomenon is very sensitive to grinding, milling and pressure, but Raman spectroscopy has the advantage that the sample does not require further preparation, in contrast to Fourier Transform Infrared spectroscopy, FT-IR, techniques; highly colored samples may affect the measurements however. Raman spectroscopy is also advantageous because it allows perturbation of the sample with external stimuli to induce SCO.
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695–710 (1926) reconsidered the linear and quadratic Stark effect from the point of view of the new quantum theory. He derived equations for the line intensities which were a decided improvement over Kramers' results obtained by the old quantum theory. While first-order perturbation effects for the Stark effect in hydrogen are in agreement for the Bohr–Sommerfeld model and the quantum-mechanical theory of the atom, higher-order effects are not. Measurements of the Stark effect under high field strengths confirmed the correctness of the quantum theory over the Bohr model.
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"Variable and Full of Perturbation" is the eighth episode of the second season, and the eighteenth episode overall, of the Canadian science fiction television series Orphan Black. It first aired in Canada on Space and the United States on BBC America on 7 June 2014. The episode was written by Karen Walton and directed by the series' co-creator John Fawcett. The series focuses on a number of identical human clones, all of whom are played by Tatiana Maslany: Sarah Manning, Alison Hendrix, Cosima Niehaus and Rachel Duncan.
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"Variable and Full of Perturbation" received mixed reviews from critics. Mark Rozeman, writing for Paste, gave the episode a rating of 6.9 out of 10 and, despite enjoying several storylines, described the introduction of Tony as "perhaps the biggest misstep in the show's brief history". He felt that the kiss between Tony and Felix was an example of "taboo-pushing gimmickry" and summarised the episode as "strange experimental tangent". Slant Magazine critic Matt Brennan found the episode "jumbled and strange" but felt that the introduction of Tony was a "delightful twist".
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From 1974 - 75 he was a Fairchild Scholar at Caltech. From 1988 onwards he was a researcher at the National Institutes of Health (National Institute of Diabetes and Digestive and Kidney Diseases) in Bethesda, Maryland, where he was a Fogarty Scholar (1987–88) and later worked as a research scientist emeritus. One of his early works from 1954 is often cited as the first use of free energy perturbation theory, and the resulting equation for the change in free energy is sometimes referred to as the "Zwanzig equation".
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He employed granular material physics to describe fragment ejecta behaviour and to predict the impact depth of projectiles as a function of impact velocity. Noting an anomalous behaviour from the experimental observations, he applied the variational perturbation theory to reveal and explain the role played by the increase in mass density during the failure of brittle materials under dynamic compression. In 1999, he accepted a postdoctoral researcher position from the Massachusetts Institute of Technology to enhance his studies in applied mechanics. After his postdoctoral studies, he lectured in ocean engineering at MIT.
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Arieh Warshel made major contributions in introducing computational methods for structure–function correlation of biological molecules, pioneering and co- pioneering programs, methods and key concepts for detailed computational studies of functional properties of biological molecules using Cartesian-based force field programs, the combined Quantum Chemistry/Molecular mechanics (i.e., QM/MM) method for simulating enzymatic reactions, the first molecular dynamics simulation of a biological process, microscopic electrostatic models for proteins, free energy perturbation in proteins and other key advances. It was for the development of these methods that Warshel shared the 2013 Nobel Prize in Chemistry.
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What distinguishes a CAS from a pure multi-agent system (MAS) is the focus on top-level properties and features like self-similarity, complexity, emergence and self-organization. A MAS is defined as a system composed of multiple interacting agents; whereas in CAS, the agents as well as the system are adaptive and the system is self- similar. A CAS is a complex, self-similar collectivity of interacting, adaptive agents. Complex Adaptive Systems are characterized by a high degree of adaptive capacity, giving them resilience in the face of perturbation.
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Abnormalities occurring in the time-domain increase the "perturbation": the variability of switching events in time relative to a reference. Since the converter is PFM type, the switching frequency changes with the fluctuation of the load. This makes it problematic using frequency- domain measurement to discriminate how much of the variation of the waveform in both timing TON and slope S1 (∆V/∆T) is caused by the response of the controller to the load and how much by the noise in the control loop circuitry. The waveform in Fig.
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He predicted, with Rashid Sunyaev, that the cosmic microwave background should undergo inverse Compton scattering. This is called the Sunyaev-Zeldovich effect, and measurements by telescopes such as the Atacama Cosmology Telescope and the South Pole Telescope has established it as one of the key observational probes of cluster cosmology. Zeldovich contributed sharp insights into the nature of the large scale structure of the universe, in particular, through the use of Lagrangian perturbation theory (the Zeldovich approximation) and the application of the Burgers' equation approach via the adhesion approximation.
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As a consequence of this mass flux, torques acting on a planet can be susceptible to local disk properties, akin to torques at work during Type I migration. Therefore, in viscous disks, Type II migration can be typically described as a modified form of Type I migration, in a unified formalism. The transition between Type I and Type II migration is generally smooth, but deviations from a smooth transition have also been found. In some situations, when planets induce eccentric perturbation in the surrounding disk's gas, Type II migration may slow down, stall, or reverse.
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The expansion has to be carried out to the same order in the continuum scheme and the lattice one. The lattice regularization was initially introduced by Wilson as a framework for studying strongly coupled theories non-perturbatively. However, it was found to be a regularization suitable also for perturbative calculations. Perturbation theory involves an expansion in the coupling constant, and is well-justified in high-energy QCD where the coupling constant is small, while it fails completely when the coupling is large and higher order corrections are larger than lower orders in the perturbative series.
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In 1961, Møller showed that a tetrad description of gravitational fields allows a more rational treatment of the energy-momentum complex than in a theory based on the metric tensor alone. The advantage of using tetrads as gravitational variables was connected with the fact that this allowed to construct expressions for the energy-momentum complex which had more satisfactory transformation properties than in a purely metric formulation. Recently it has been shown that total energy of matter and gravitation is proportional to the Ricci scalar of three-space up to linear order of perturbation.
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Greitzer used a Helmholtz resonator type of compression system model to predict the transient response of a compression system after a small perturbation superimposed on a steady operating condition. He found a non-dimensional parameter which predicted which mode of compressor instability, rotating stall or surge, would result. The parameter used the rotor speed, Helmholtz resonator frequency of the system and an "effective length" of the compressor duct. It had a critical value which predicted either rotating stall or surge where the slope of pressure ratio against flow changed from negative to positive.
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However, at the time the parsimony of separate memory stores was a contested notion. A summary of the evidence given for the distinction between long-term and short-term stores is given below. Additionally, Atkinson and Shiffrin included a sensory register alongside the previously theorized primary and secondary memory, as well as a variety of control processes which regulate the transfer of memory. Following its first publication, multiple extensions of the model have been put forth such as a precategorical acoustic store, the search of associative memory model, the perturbation model, and permastore.
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The nuclear Overhauser effect (NOE) is the transfer of nuclear spin polarization from one population of spin-active nuclei (e.g. 1H, 13C, 15N etc.) to another via cross-relaxation. A phenomenological definition of the NOE in nuclear magnetic resonance spectroscopy (NMR) is the change in the integrated intensity (positive or negative) of one NMR resonance that occurs when another is saturated by irradiation with an RF field. The change in resonance intensity of a nucleus is a consequence of the nucleus being close in space to those directly affected by the RF perturbation.
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Since the rate of nuclear reactions in these shells is very sensitively dependent on pressure, the added pressure results in a large release of energy, and the core is pushed back the other way. This in turn adds greater pressure on the other side, and we find that the core begins to oscillate. It has been shown that many such modes are overstable in heavy stars, that is, a small perturbation becomes large over time. When the star explodes, the core has additional momentum in some direction, which we observe as the kick.
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An optical modulator is an optical device which is used to modulate a beam of light with a perturbation device. It is a kind of transmitter to convert information to optical binary signal through optical fiber (optical waveguide) or transmission medium of optical frequency in fiber optic communication. There are several methods to manipulate this device depending on the parameter of a light beam like amplitude modulator (majority), phase modulator, polarization modulator etc. The easiest way to obtain modulation is modulation of intensity of a light by the current driving the light source (laser diode).
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In general, these disturbances take an arbitrary form and are thus difficult to consider rigorously. It is therefore helpful to take a Fourier transform of the disturbances to decompose the arbitrary disturbances into perturbations of various single wavelengths on the surface of the thread. In doing so, this allows one to determine which wavelengths of the disturbance will grow and which will decay in time. The growth and decay of wavelengths can be determined by examining the change in pressure a perturbation wavelength imposes on the interior of the fluid thread.
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The “Micromegas “ (Micro-MEsh Gaseous Structure) detector is a gaseous particle detector coming from the development of wire chamber. Invented in 1992 by Georges Charpak and Ioannis Giomataris, the Micromegas detectors are mainly used in experimental physics, in particular in particle physics, nuclear physics and astrophysics for the detection of ionising particles. A Micromegas detector in function on the COMPASS spectrometer The Micromegas are light detectors in order to minimize the perturbation on the impinging particle. From their small amplification gap, they have fast signals in the order of 100 nanoseconds.
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Orbit modeling is the process of creating mathematical models to simulate motion of a massive body as it moves in orbit around another massive body due to gravity. Other forces such as gravitational attraction from tertiary bodies, air resistance, solar pressure, or thrust from a propulsion system are typically modeled as secondary effects. Directly modeling an orbit can push the limits of machine precision due to the need to model small perturbations to very large orbits. Because of this, perturbation methods are often used to model the orbit in order to achieve better accuracy.
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The effective one-body or EOB formalism is an analytical approach to the gravitational two-body problem in general relativity. It was introduced by Alessandra Buonanno and Thibault Damour in 1999. It aims to describe all different phases of the two-body dynamics in a single analytical method. The theory allows calculations to not only be made in particular limits, such as post-Newtonian theory in the early inspiral, when the objects are at large separation, or black hole perturbation theory, when the two objects differ greatly in mass.
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By considering the propagation of the negative energy modes of the electron field backward in time, Ernst Stueckelberg reached a pictorial understanding of the fact that the particle and antiparticle have equal mass m and spin J but opposite charges q. This allowed him to rewrite perturbation theory precisely in the form of diagrams. Richard Feynman later gave an independent systematic derivation of these diagrams from a particle formalism, and they are now called Feynman diagrams. Each line of a diagram represents a particle propagating either backward or forward in time.
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The trajectory of successional change can be influenced by site conditions, by the character of the events initiating succession (perturbations), by the interactions of the species present, and by more stochastic factors such as availability of colonists or seeds or weather conditions at the time of disturbance. Some of these factors contribute to predictability of succession dynamics; others add more probabilistic elements. Two important perturbation factors today are human actions and climatic change. In general, communities in early succession will be dominated by fast-growing, well-dispersed species (opportunist, fugitive, or r-selected life-histories).
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MRF is a transcription factor of critical importance in the development and maintenance of myelin sheaths. A perturbation of oligodendrocyte maturation and the myelination process might, therefore, be an underlying mechanism of the neurological deficits. Curiously, in 2011 fibroblast cells derived from patients with Niemann-Pick type C1 disease were shown to be resistant to Ebola virus because of mutations in the NPC1 protein, which is needed for viral escape from the vesicular compartment. Other studies have uncovered small molecules which inhibit the receptor and may be a potential therapeutic strategy.
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The ISCI energy group is interested in the development of renewable energies in Chile and the electricity sector as a whole. Researchers of the Energy group make both theoretical and applied contributions. In the area of theory contributions is worth to mention a methodology to perform the network constrained economic dispatch optimization problem; a stochastic perturbation model to deal with uncertainties of power system stability; an optimal allocation algorithm of wind turbines by considering transmission security constraints, and new applications of smart grids in remote areas of the country.
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Calculating isomerase kinetics from experimental data can be more difficult than for other enzymes because the use of product inhibition experiments is impractical. That is, isomerization is not an irreversible reaction since a reaction vessel will contain one substrate and one product so the typical simplified model for calculating reaction kinetics does not hold. There are also practical difficulties in determining the rate-determining step at high concentrations in a single isomerization. Instead, tracer perturbation can overcome these technical difficulties if there are two forms of the unbound enzyme.
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For example, Gene Set Enrichment Analysis (GSEA) considers the perturbation of whole (functionally related) gene sets rather than of single genes. These gene sets might be known biochemical pathways or otherwise functionally related genes. The advantage of this approach is that it is more robust: It is more likely that a single gene is found to be falsely perturbed than it is that a whole pathway is falsely perturbed. Furthermore, one can integrate the accumulated knowledge about biochemical pathways (like the JAK-STAT signaling pathway) using this approach.
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His main research have been on tumor suppressor hDlg which includes an in-depth characterization of the combinations of hDlg isoforms present in multiple tissues and cell lines to correlate the presence of specific alternatively spliced insertions with a specific function of this tumor suppressor. He also studies the perturbation of hDlg distribution in two skin disease: psoriasis, characterized by a hyper-proliferation of basal cells, and Darier's disease, characterized by blisters resulting from the loss of cell adhesion in the supra-basal layers. He is a founding member of BioVisions.
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However, it is common to call spherically symmetric models or non-homogeneous models as inhomogeneous. In inhomogeneous cosmology, the large-scale structure of the universe is modeled by exact solutions of the Einstein field equations (i.e. non-perturbatively), unlike cosmological perturbation theory, which is study of the universe that takes structure formation (galaxies, galaxy clusters, the cosmic web) into account but in a perturbative way.Krasinski, A., Inhomogeneous Cosmological Models, (1997) Cambridge UP, Inhomogeneous cosmology usually includes the study of structure in the Universe by means of exact solutions of Einstein's field equations (i.e.
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The unravelling of the problem of three bodies also had practical importance. It allowed sailors to determine the longitudinal direction of their ships, which was crucial not only in sailing to a location, but finding their way home as well. This held economic implications as well, because sailors were able to more easily find destinations of trade based on the longitudinal measures. Clairaut subsequently wrote various papers on the orbit of the Moon, and on the motion of comets as affected by the perturbation of the planets, particularly on the path of Halley's comet.
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Instead of a model-dependent treatment in terms of constituent quarks, hadrons are represented by their interpolating quark currents taken at large virtualities. The correlation function of these currents is introduced and treated in the framework of the operator product expansion (OPE), where the short and long-distance quark-gluon interactions are separated. The former are calculated using QCD perturbation theory, whereas the latter are parametrized in terms of universal vacuum condensates or light-cone distribution amplitudes. The result of the QCD calculation is then matched, via dispersion relation, to a sum over hadronic states.
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However, the latter is not a valid test function (it is not even a proper function). In the definition, the functional derivative describes how the functional F[\varphi(x)] changes as a result of a small change in the entire function \varphi(x). The particular form of the change in \varphi(x) is not specified, but it should stretch over the whole interval on which x is defined. Employing the particular form of the perturbation given by the delta function has the meaning that \varphi(x) is varied only in the point y.
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Asbestos fibers have been shown to alter the function and secretory properties of macrophages, ultimately creating conditions which favour the development of mesothelioma. Following asbestos phagocytosis, macrophages generate increased amounts of hydroxyl radicals, which are normal by-products of cellular anaerobic metabolism. However, these free radicals are also known clastogenic (chromosome-breaking) and membrane-active agents thought to promote asbestos carcinogenicity. These oxidants can participate in the oncogenic process by directly and indirectly interacting with DNA, modifying membrane-associated cellular events, including oncogene activation and perturbation of cellular antioxidant defences.
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The φ4 theory example above demonstrates that the coupling parameters of a quantum field theory can be scale-dependent even if the corresponding classical field theory is scale-invariant (or conformally invariant). If this is the case, the classical scale (or conformal) invariance is said to be anomalous. A classically scale invariant field theory, where scale invariance is broken by quantum effects, provides an explication of the nearly exponential expansion of the early universe called cosmic inflation, as long as the theory can be studied through perturbation theory.
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William L. Jorgensen (born October 5, 1949, New York) is a Sterling Professor of Chemistry at Yale University. He is considered a pioneer in the field of computational chemistry. Some of his contributions include the TIP3P, TIP4P, and TIP5P water models, the OPLS force field, and his work on free-energy perturbation theory for modeling reactions in solution, protein-ligand binding, and drug design; he has over 400 publications in the field. Jorgensen has been the Editor of the ACS Journal of Chemical Theory and Computation since its founding in 2005.
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In the opposite limit, the infrared limit, the situation is the opposite, as the coupling is too large for perturbation theory to be reliable. Most of the difficulties that research meets is just managing the theory at low energies. That is the interesting case, being inherent to the description of hadronic matter and, more generally, to all the observed bound states of gluons and quarks and their confinement (see hadrons). The most used method to study the theory in this limit is to try to solve it on computers (see lattice gauge theory).
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"I find Hornblower admirable – vastly entertaining". He relates that "this caused perturbation in Middle East Headquarters, where they imagined that 'Hornblower' was the code word for some special operation of which they had not been told." After the war this was naturally used as an excellent "blurb" by Forester's publishers. The popular Richard Sharpe novels by Bernard Cornwell were inspired by the Hornblower series; Cornwell avidly read the series as a child, and was disappointed to learn that there was no similar series chronicling the Napoleonic Wars on land.
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Injected instrument response function and the reconstructed DTOF The theory of light propagation in diffusive media is usually dealt with using the framework of radiative transfer theory under the multiple scattering regime. It has been demonstrated that radiative transfer equation under the diffusion approximation yields sufficiently accurate solutions for practical applications. For example, it can be applied for the semi-infinite geometry or the infinite slab geometry, using proper boundary conditions. The system is considered as a homogeneous background and an inclusion is considered as an absorption or scattering perturbation.
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In general these circuits don't have simple mathematical solutions. To calculate the current and voltage in them generally requires either graphical methods or simulation on computers using electronic circuit simulation programs like SPICE. However in some electronic circuits such as radio receivers, telecommunications, sensors, instrumentation and signal processing circuits, the AC signals are "small" compared to the DC voltages and currents in the circuit. In these, perturbation theory can be used to derive an approximate AC equivalent circuit which is linear, allowing the AC behavior of the circuit to be calculated easily.
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In theoretical physics, a near-extremal black hole is a black hole which is not far from the minimal possible mass that can be compatible with the given charges and angular momentum. The calculations of the properties of near- extremal black holes are usually performed using perturbation theory around the extremal black hole; the expansion parameter is called non-extremality. In supersymmetric theories, near-extremal black holes are often small perturbations of supersymmetric black holes. Such black holes have a very small Hawking temperature and consequently emit a small amount of Hawking radiation.
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In quantum mechanics, the Schrieffer–Wolff transformation is a unitary transformation used to perturbatively diagonalize the system Hamiltonian to first order in the interaction. As such, the Schrieffer-Wolff transformation is an operator version of second-order perturbation theory. The Schrieffer- Wolff transformation is often used to project out the high energy excitations of a given quantum many-body Hamiltonian in order to obtain an effective low energy model. The Schrieffer–Wolff transformation thus provides a controlled perturbative way to study the strong coupling regime of quantum-many body Hamiltonians.
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Although most lattice field theories are not exactly solvable, they are of tremendous appeal because they can be studied by simulation on a computer. One hopes that, by performing simulations on larger and larger lattices, while making the lattice spacing smaller and smaller, one will be able to recover the behaviour of the continuum theory. Just as in all lattice models, numerical simulation gives access to field configurations that are not accessible to perturbation theory, such as solitons. Likewise, non-trivial vacuum states can be discovered and probed.
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Patterning mechanisms such as those described by the French flag model can be perturbed at many levels (production and stochasticity of the diffusion of the morphogen, production of the receptor, stochastic of the signaling cascade, etc). Patterning is therefore inherently noisy. Robustness against this noise and genetic perturbation is therefore necessary to ensure proper that cells measure accurately positional information. Studies of the zebrafish neural tube and antero-posterior patternings has shown that noisy signaling leads to imperfect cell differentiation that is later corrected by transdifferentiation, migration or cell death of the misplaced cells.
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Dyson proved in 1949 that this is only possible for a small class of theories called "renormalizable theories", of which QED is an example. However, most theories, including the Fermi theory of the weak interaction, are "non-renormalizable". Any perturbative calculation in these theories beyond the first order would result in infinities that could not be removed by redefining a finite number of physical quantities. The second major problem stemmed from the limited validity of the Feynman diagram method, which is based on a series expansion in perturbation theory.
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The interpretation of an interaction as a sum of intermediate states involving the exchange of various virtual particles only makes sense in the framework of perturbation theory. In contrast, non-perturbative methods in QFT treat the interacting Lagrangian as a whole without any series expansion. Instead of particles that carry interactions, these methods have spawned such concepts as 't Hooft–Polyakov monopole, domain wall, flux tube, and instanton. Examples of QFTs that are completely solvable non-perturbatively include minimal models of conformal field theory and the Thirring model.
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In particle physics, quantum electrodynamics (QED) is the relativistic quantum field theory of electrodynamics. In essence, it describes how light and matter interact and is the first theory where full agreement between quantum mechanics and special relativity is achieved. QED mathematically describes all phenomena involving electrically charged particles interacting by means of exchange of photons and represents the quantum counterpart of classical electromagnetism giving a complete account of matter and light interaction. In technical terms, QED can be described as a perturbation theory of the electromagnetic quantum vacuum.
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An argument by Freeman Dyson shows that the radius of convergence of the perturbation series in QED is zero. The basic argument goes as follows: if the coupling constant were negative, this would be equivalent to the Coulomb force constant being negative. This would "reverse" the electromagnetic interaction so that like charges would attract and unlike charges would repel. This would render the vacuum unstable against decay into a cluster of electrons on one side of the universe and a cluster of positrons on the other side of the universe.
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With a similar methodology, but using the term CRISP-seq instead of Perturb-seq, the paper "Dissecting Immune Circuits by Linking CRISPR-Pooled Screens with Single-Cell RNA-Seq" performed a proof of concept experiment by using the technique to probe regulatory pathways related to innate immunity in mice. Lethality of each perturbation and epistasis analyses in cells with multiple perturbations was also investigated in these papers. Perturb-seq has so far been used with very few perturbations per experiment, but it can theoretically be scaled up to address the whole genome.
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Meanwhile, blood-feeding diets cause a markable decrease in microbial richness, but this decrease is eventually corrected after a short period of time. Sandflies infected with Leishmania experience a progressive decline in the bacterial diversity of the midgut. Interestingly, the perturbation of the midgut microbiome due to the introduction of antibiotics causes the sand flies to become unable to support the parasitic growth of the pathogen. This highlights the bacterial microbiome of the L. longipalpis midgut as another area of interest that can be explored to control the disease.
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Precise expressions for the transition probability, based on first-order perturbation Hamiltonians, can be found in Thompson and Baker. Often, all of these terms are not known, so most analyses compare measured yields with external standards of known composition. Ratios of the acquired data to standards can eliminate common terms, especially experimental setup characteristics and material parameters, and can be used to determine element composition. Comparison techniques work best for samples of homogeneous binary materials or uniform surface layers, while elemental identification is best obtained from comparison of pure samples.
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Control of chaos is the stabilization, by means of small system perturbations, of one of these unstable periodic orbits. The result is to render an otherwise chaotic motion more stable and predictable, which is often an advantage. The perturbation must be tiny compared to the overall size of the attractor of the system to avoid significant modification of the system's natural dynamics. Several techniques have been devised for chaos control, but most are developments of two basic approaches: the OGY (Ott, Grebogi and Yorke) method, and Pyragas continuous control.
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Because the aim of community fingerprinting is to gain an overall understanding of community structure, it is a particularly useful technique for analyzing time- series data collected from the field. For example, one could study the pattern of microbial succession in a habitat, or one could examine the response of a microbial community to an environmental perturbation, such as the release of a pollutant. Depending on what information is desired, different genes may be targeted. The most common are small subunit ribosomal RNA (rRNA) genes, such as 16S rRNA.
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An important property of Axiom A systems is their structural stability against small perturbations.Abraham and Marsden, Foundations of Mechanics (1978) Benjamin/Cummings Publishing, see Section 7.5 That is, trajectories of the perturbed system remain in 1-1 topological correspondence with the unperturbed system. This property is important, in that it shows that Axiom A systems are not exceptional, but are in a sense 'robust'. More precisely, for every C1-perturbation fε of f, its non-wandering set is formed by two compact, fε- invariant subsets Ω1 and Ω2.
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In particle physics, dimensional transmutation is a physical mechanism providing a linkage between a dimensionless parameter and a dimensionful parameter. In classical field theory, such as gauge theory in four-dimensional spacetime, the coupling constant is a dimensionless constant. However, upon quantization, logarithmic divergences in one-loop diagrams of perturbation theory imply that this "constant" actually depends on the typical energy scale of the processes under considerations, called the renormalization group (RG) scale. This "running" of the coupling is specified by the beta-function of the renormalization group.
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In his Reminiscences, Hylleraas referred to the period 1925–1930 as the Golden Age of atomic physics. It was a time when Bohr's theory of the atom was being replaced by the new quantum mechanics. By 1926, the one-electron hydrogen problem had been solved and Heisenberg had formulated the two-electron helium problem quantum mechanically but a simple first-order perturbation treatment yielded an ionization potential considerably in error with experimental measurement. Born considered it crucial for quantum mechanics to provide a result in much better agreement with experiment.
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The planetary companion was discovered in 2010 with the HARPS instrument, which measured the radial velocity displacement caused by the gravitational perturbation of the star by the planet. This data provided an orbital period of 1,845 days and set a lower bound of the planet's mass at 95% of the mass of Jupiter. The planetary system of HD 25171 is analogous to Solar System in the sense that a gas giant orbiting outside the frost line, far enough to do not destabilize orbits within a circumstellar habitable zone.
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Malchiodi received his Ph.D. in mathematics from the International School for Advanced Studies in 2000 under the supervision of Antonio Ambrosetti. He is a professor of mathematics at the Scuola Normale Superiore at Pisa. He was previously professor of mathematics at the International School for Advanced Studies and at the University of Warwick. Malchiodi has developed topological and analytical methods allowing to deal with a number of questions in geometric analysis, such as the Yamabe problem, the scalar curvature problem, problems coming from fourth order conformal geometry and concentration for singular perturbation problems.
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In 1958, he graduated from Queen Anne High School, Seattle, Washington. He received his BS in physics from MIT as a National Sloan Scholar, 1962. He received his MS in physics from the University of Washington, 1963. He obtained his PhD at the University of Washington with a thesis entitled Sixth Order Charge Renormalization Constant, under Marshall Baker, 1970, calculating the divergent part of the inverse charge renormalization constant in quantum electrodynamics to sixth order in perturbation theory in Feynman gauge to verify the gauge invariance of the calculation.
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Indeed, in 2012, Stephan and coworkers were able to develop a borenium-based FLP system capable of activating H2 stoichiometrically in the presence of phosphine. In 2015, Devillard et al. synthesized a naphthyl-bridged intramolecular borenium-containing FLP capable of activating H2 with concomitant hydrogenolysis of a mesityl ligand. A second-order perturbation theory analysis of the natural bond orbitals (NBOs) of the intermediate in this reaction involved with H2 activation showed a 281.8 kcal/mol interaction between the sigma bond of H2 and the 2p orbital of the cationic boron.
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The term 'variety' was introduced by W. Ross Ashby to denote the count of the total number of states of a system. The condition for dynamic stability under perturbation (or input) was described by his Law of Requisite Variety. Ashby says:Ashby (1956) > Thus, if the order of occurrence is ignored, the collection > c, b, c, a, c, c, a, b, c, b, b, a > which contains twelve elements, contains only three distinct elements- a, > b, c. Such a set will be said to have a variety of three elements.
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For example, the termites in a mound have physiology, biochemistry and biological development that are at one level of analysis, but their social behavior and mound building is a property that emerges from the collection of termites and needs to be analyzed at a different level. ; Relationships are non-linear : In practical terms, this means a small perturbation may cause a large effect (see butterfly effect), a proportional effect, or even no effect at all. In linear systems, the effect is always directly proportional to cause. See nonlinearity.
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Orbital topological stability of a dynamical system means that for any sufficiently small perturbation (in the C1-metric), there exists a homeomorphism close to the identity map which transforms the orbits of the original dynamical system to the orbits of the perturbed system (cf structural stability). The first condition of the theorem is known as global hyperbolicity. A zero of a vector field v, i.e. a point x0 where v(x0)=0, is said to be hyperbolic if none of the eigenvalues of the linearization of v at x0 is purely imaginary.
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In a disk this results in the orbits rolling with respect to each other so that the orbits are no longer co-planar. The gravity of the objects now exerts forces on each other that are out of planes of their orbits. Unlike the force due to the initial perturbation these forces are in opposite directions, up and down respectively, on the inbound and outbound portions of their orbits. The resulting torque causes their orbits to rotate about their minor axes, lifting their aphelia, causing the disk to form a cone.
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Vladimir Gribov noted that the Froissart bound combined with the assumption of maximum possible scattering implied there was a Regge trajectory that would lead to logarithmically rising cross sections, a trajectory nowadays known as the pomeron. He went on to formulate a quantitative perturbation theory for near beam line scattering dominated by multi-pomeron exchange. From the fundamental observation that hadrons are composite, there grew two points of view. Some correctly advocated that there were elementary particles, nowadays called quarks and gluons, which made a quantum field theory in which the hadrons were bound states.
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The most widely used NN potentials are the Paris potential, the Argonne AV18 potential, the CD-Bonn potential and the Nijmegen potentials. A more recent approach is to develop effective field theories for a consistent description of nucleon–nucleon and three-nucleon forces. Quantum hadrodynamics is an effective field theory of the nuclear force, comparable to QCD for color interactions and QED for electromagnetic interactions. Additionally, chiral symmetry breaking can be analyzed in terms of an effective field theory (called chiral perturbation theory) which allows perturbative calculations of the interactions between nucleons with pions as exchange particles.
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The Breit equation is a relativistic wave equation derived by Gregory Breit in 1929 based on the Dirac equation, which formally describes two or more massive spin-1/2 particles (electrons, for example) interacting electromagnetically to the first order in perturbation theory. It accounts for magnetic interactions and retardation effects to the order of 1/c2. When other quantum electrodynamic effects are negligible, this equation has been shown to give results in good agreement with experiment. It was originally derived from the Darwin Lagrangian but later vindicated by the Wheeler–Feynman absorber theory and eventually quantum electrodynamics.
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If two string theories are related by S-duality, then one theory with a strong coupling constant is the same as the other theory with weak coupling constant. The theory with strong coupling cannot be understood by means of perturbation theory, but the theory with weak coupling can. So if the two theories are related by S-duality, then we just need to understand the weak theory, and that is equivalent to understanding the strong theory. Superstring theories related by S-duality are: type I superstring theory with heterotic SO(32) superstring theory, and type IIB theory with itself.
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A constituent quark is a current quark with a notional "covering" induced by the renormalization group. In the low-energy limit of QCD, a description by means of perturbation theory is not possible: Here, no asymptotic freedom exists, but collective interactions between valence quarks and sea quarks gain strongly in significance. Part of the effects of virtual quarks and virtual gluons in the "sea" can be assigned to a quark so well, that the term "constituent quark" can serve as an effective description of the low-energy system. Constituent quarks appear like "dressed" current quarks, i.e.
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A few alignment algorithms output site-specific scores that allow the selection of high-confidence regions. Such a service was first offered by the SOAP program, which tests the robustness of each column to perturbation in the parameters of the popular alignment program CLUSTALW. The T-Coffee program uses a library of alignments in the construction of the final MSA, and its output MSA is colored according to confidence scores that reflect the agreement between different alignments in the library regarding each aligned residue. Its extension, TCS : (Transitive Consistency Score), uses T-Coffee libraries of pairwise alignments to evaluate any third party MSA.
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In 1958 Kuroda showed that the Weyl–von Neumann theorem is also true if the Hilbert–Schmidt class is replaced by any Schatten class Sp with p ≠ 1. For S1, the trace-class operators, the situation is quite different. The Kato–Rosenblum theorem, proved in 1957 using scattering theory, states that if two bounded self-adjoint operators differ by a trace-class operator, then their absolutely continuous parts are unitarily equivalent. In particular if a self-adjoint operator has absolutely continuous spectrum, no perturbation of it by a trace-class operator can be unitarily equivalent to a diagonal operator.
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In a career spanning four decades, he made important contributions to a number of fields, including perturbation techniques, nonlinear oscillations, aerodynamics, flight mechanics, acoustics, ship motions, hydrodynamic stability, nonlinear waves, structural dynamics, experimental dynamics, linear and nonlinear control, and micromechanics, and fluid dynamics. He authored over a thousand publications, which have collectively been cited at least 43,364 times by other scholars, as of 2017. His contributions have had a significant influence on the lives of many people. His contributions in nonlinear dynamics have had an impact on numerous practical applications, including devices, structures and systems that are common in daily life.
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Hermann Hartmann in 1950 Hermann Hartmann (4 May 1914 in Bischofsheim an der Rhön – 22 October 1984 in Glashütten im Taunus) was a German chemist and professor and researcher in physical and theoretical chemistry at the University of Frankfurt am Main. He contributed to all fields of physical chemistry and was instrumental in establishing theoretical chemistry by developing Ligand field theory (1947) and other quantum chemical models including the Hartmann Potential (1971). He also formulated a new perturbation theory (1970–1977) as part of his pioneering research towards a unified field theory of chemical bonding based on a non-linear Schrödinger equation (1980).
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Let G be an open domain in Rn with compact closure and smooth (n−1)-dimensional boundary. Consider the space X1(G) consisting of restrictions to G of C1 vector fields on Rn that are transversal to the boundary of G and are inward oriented. This space is endowed with the C1 metric in the usual fashion. A vector field F ∈ X1(G) is weakly structurally stable if for any sufficiently small perturbation F1, the corresponding flows are topologically equivalent on G: there exists a homeomorphism h: G → G which transforms the oriented trajectories of F into the oriented trajectories of F1.
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"Relating the sigmoids at X-ray (and other) wavelengths to magnetic structures and current systems in the solar atmosphere is the key to understanding their relationship to CMEs." The first detection of a Coronal mass ejection (CME) as such was made on December 1, 1971, by R. Tousey of the US Naval Research Laboratory using OSO 7. Earlier observations of coronal transients or even phenomena observed visually during solar eclipses are now understood as essentially the same thing. The largest geomagnetic perturbation, resulting presumably from a "prehistoric" CME, coincided with the first-observed solar flare, in 1859.
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Transformation in economics refers to a long-term change in dominant economic activity in terms of prevailing relative engagement or employment of able individuals. Human economic systems undergo a number of deviations and departures from the "normal" state, trend or development. Among them are Disturbance (short-term disruption, temporary disorder), Perturbation (persistent or repeated divergence, predicament, decline or crisis), Deformation (damage, regime change, loss of self-sustainability, distortion), Transformation (long-term change, restructuring, conversion, new “normal”) and Renewal (rebirth, transmutation, corso-ricorso, renaissance, new beginning). Transformation is a unidirectional and irreversible change in dominant human economic activity (economic sector).
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300x300px Precise tracking of spacecraft is of prime importance for accurate gravity modeling, as gravity models are developed from observing tiny perturbation of spacecraft, i.e. small variation in velocity and altitude. The tracking is done basically by the antennae of the Deep Space Network (DSN), with one-way, two-way and three- way Doppler and range tracking applied. One-way tracking means the data is transmitted in one way to the DSN from the spacecraft, while two-way and three-way involve transmitting signals from Earth to the spacecraft (uplink), and thereafter transponded coherently back to the Earth (downlink).
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An isotopic labeling experiment can be designed to be directly analogous to a traditional crossover experiment, but there are many additional ways of carrying out isotopic labeling experiments. Although isotopic labeling experiments have the advantage of using the smallest perturbation to the reaction system, they are limited by the possibility of isotopic exchange with solvent or other species present in the reaction mixture. If the isotopic label exchanges with another isotope of the same atom in the solvent, the results of an isotopic labeling experiment are unusable. This limits the use of deuterium labeling at certain positions in protic solvents, for example.
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In quantum field theory and string theory, a coupling constant is a number that controls the strength of interactions in the theory. For example, the strength of gravity is described by a number called Newton's constant, which appears in Newton's law of gravity and also in the equations of Albert Einstein's general theory of relativity. Similarly, the strength of the electromagnetic force is described by a coupling constant, which is related to the charge carried by a single proton. To compute observable quantities in quantum field theory or string theory, physicists typically apply the methods of perturbation theory.
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The formalism, now known as De Donder–Weyl (DW) theory, was developed by Théophile De DonderThéophile De Donder, "Théorie invariantive du calcul des variations," Gauthier-Villars, 1930. Frédéric Hélein: Hamiltonian formalisms for multidimensional calculus of variations and perturbation theory In Haïm Brézis, Felix E. Browder, Abbas Bahri, Sergiu Klainerman, Michael Vogelius (ads.): Noncompact problems at the intersection of geometry, analysis, and topology, American Mathematical Society, 2004, pp. 127–148, p. 131, , and Hermann Weyl. Hermann Weyl made his proposal in 1934 being inspired by the work of Constantin Carathéodory, which in turn was founded on the work of Vito Volterra.
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In the same era, he introduced non-perturbative methods into quantum field theory, by calculating the rate at which electron–positron pairs are created by tunneling in an electric field, a process now known as the "Schwinger effect." This effect could not be seen in any finite order in perturbation theory. Schwinger's foundational work on quantum field theory constructed the modern framework of field correlation functions and their equations of motion. His approach started with a quantum action and allowed bosons and fermions to be treated equally for the first time, using a differential form of Grassman integration.
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Computational physics problems are in general very difficult to solve exactly. This is due to several (mathematical) reasons: lack of algebraic and/or analytic solubility, complexity, and chaos. For example, - even apparently simple problems, such as calculating the wavefunction of an electron orbiting an atom in a strong electric field (Stark effect), may require great effort to formulate a practical algorithm (if one can be found); other cruder or brute- force techniques, such as graphical methods or root finding, may be required. On the more advanced side, mathematical perturbation theory is also sometimes used (a working is shown for this particular example here).
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An alternative theoretical tool to cope with strong fluctuations problems occurring in field theories has been provided in the late 1940s by the concept of renormalization, which has originally been devised to calculate functional integrals arising in quantum field theories (QFT's). In QFT's a standard approximation strategy is to expand the functional integrals in a power series in the coupling constant using perturbation theory. Unfortunately, generally most of the expansion terms turn out to be infinite, rendering such calculations impracticable (Shirkov 2001). A way to remove the infinities from QFT's is to make use of the concept of renormalization (Baeurle 2007).
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It mainly consists in replacing the bare values of the coupling parameters, like e.g. electric charges or masses, by renormalized coupling parameters and requiring that the physical quantities do not change under this transformation, thereby leading to finite terms in the perturbation expansion. A simple physical picture of the procedure of renormalization can be drawn from the example of a classical electrical charge, Q, inserted into a polarizable medium, such as in an electrolyte solution. At a distance r from the charge due to polarization of the medium, its Coulomb field will effectively depend on a function Q (r), i.e.
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Blood-related pathology is seen in all patients. Typically diagnosed at birth, congenital nonspherocytic hemolytic anemia is characterised by premature destruction of red blood cells without apparent abnormality in shape. Erythrocyte dependency on anaerobic glycolysis for ATP homeostasis, causes perturbation of this pathway to result in disruption of cellular processes including electrostatic membrane gradients (typically maintained through transporters of high energetic demand) ultimately leading to membrane instability and lysis. Pathway summary: heme degradation to bilirubin This shortened erythrocyte life-span and increased destruction links to hyperbilirubinemia which often presents as jaundice in the accumulation of bilirubin through excessive hemoglobin breakdown.
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One of the recurring issues in consciousness is the existence of qualia, such as redness, warmth and pain. It is not enough to identify each quale with a particular neuron or neuronal group; what is crucial is all the other groups which are highly influenced by the sensation and will fire at the same time. Thus each conscious state deserves to be called a quale. A small perturbation of a group of neurons can affect the whole in a very short space of time provided the system is kept in a state of readiness by the thalamus.
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Jemmis is engaged in the study of structure and reactivity of molecules, clusters and solids using theoretical methods. A constant attempt is made by his group to find common threads between problems of different areas, viz. between organic and organometallic chemistry; amongst the chemistry of various main group elements; between polymorphs of elements and their compounds; etc. His research group not only gets numbers as an answer to a problem, but also tries to find out why the numbers turn out the way they do, based on overlap of orbitals, perturbation theory and symmetry, and devise transferable models.
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However, there are several major problems with the methane hydrate dissociation hypothesis. The most parsimonious interpretation for surface-water forams to show the excursion before their benthic counterparts (as in the Thomas et al. paper) is that the perturbation occurred from the top down, and not the bottom up. If the anomalous (in whatever form: CH4 or CO2) entered the atmospheric carbon reservoir first, and then diffused into the surface ocean waters, which mix with the deeper ocean waters over much longer time-scales, we would expect to observe the planktonics shifting toward lighter values before the benthics.
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Hypersensitivity responses to commensal enteric microbiota and a perturbation of microbial ecology is observed in many patients suffering from chronic enterocolitis. This alternative theory coincides with the observation that women without a history of urinary tract or vaginal infections harbor higher antibody levels against vaginal lactobacilli than women with a history of these infections. Alvarez-Olmos and her coworkers reported an approximately fourfold elevation of total IgG and a threefold elevation of total IgA concentration in the cervicovaginal secretions of adolescent women colonized with -producing lactobacilli (associated with vaginal health) in comparison to those colonized with non-- producing lactobacilli. Goisis et al.
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The Melnikov method is used in many cases to predict the occurrence of chaotic orbits in non-autonomous smooth nonlinear systems under periodic perturbation. According to the method is possible to construct a function called "Melnikov function", and hence to predict either regular or chaotic behavior of a studied dynamical system. Thus, the Melnikov function will be used to determine a measure of distance between stable and unstable manifolds in the Poincaré map. Moreover, when this measure is equal to zero, by the method, those manifolds crossed each other transversally and from that crossing the system will become chaotic.
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Semiclassical Transition State Theory (SCTST) is an efficient chemical rate theory, which aims to calculate accurate rate constants of chemical reactions, including nuclear quantum effects such as tunnelling, from ab initio quantum chemistry. The method makes use of the semiclassical WKB wavefunction, Bohr- sommerfeld theory and vibrational perturbation theory to derive an analytical relation for the probability of a particle transmitting through a potential barrier at some energy, E. It was first developed by Bill Miller and coworkers in the 1970's, and has been further developed to allow for application to larger systems and using more accurate potentials.
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140-3, In the case of temperature jump, the perturbation involves rapid heating which changes the value of the equilibrium constant, followed by relaxation to equilibrium at the new temperature. The heating usually involves discharging of a capacitor (in the kV range) through a small volume (< 1 mL) of a conducting solution containing the molecule/reaction to be studied. In some versions of the apparatus used, the solution is heated instead by the output of a pulsed laser which emits in the near infra-red. When laser heating is employed, the solution need not be conducting.
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Son of Domenico, owner of a hotel, and Domenica Maltauro, he studied at the University of Padua. In 1848 he appeared in the journal Astronomische Nachrichten connected to an article about the observations of the planet Neptune. The presence of the planet was postulated on the basis of the perturbation of the orbit of Uranus by Le Verrier and was observed for the first time only two years earlier. In 1850-1851 he was nominated assistant in the department of physics and geodesy in Padua, and assistant astronomer at the Royal Observatory, under supervision of Professor Giovanni Santini in 1853.
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Animals undergoing split-belt adaption adjust their interlimb coordination pattern to regain overall gait symmetry. Split-belt adaptation has a notable after-effect period (limbs driven at the same speed) in which the interlimb coordination pattern remains altered from that during the pre-adaptation period for some time after the split-belt perturbation period. The after-effect, however, is context- dependent and therefore, will only exist in the same locomotor environment in which the adaptation had occurred. Moreover, split-belt adaptation has spatial (placement of the limb) and temporal (timing of limb movement) components that are dissociable at the behavioral and circuit level.
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In symptomatic cases, a wide spectrum of symptoms may be expressed, including headaches, dizziness, and seizures. Brain infection by the cysticerci is called neurocysticercosis and is the leading cause of seizures worldwide. In more severe cases, dementia or hypertension can occur due to perturbation of the normal circulation of cerebrospinal fluid. (Any increase in intracranial pressure will result in a corresponding increase in arterial blood pressure, as the body seeks to maintain circulation to the brain.) The severity of cysticercosis depends on location, size and number of parasite larvae in tissues, as well as the host immune response.
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Finite differences are then used to approximate the spatial derivatives, and the resulting system of equations is solved by MOL. It is also possible to solve elliptical problems by a semi- analytical method of lines. In this method, the discretization process results in a set of ODE's that are solved by exploiting properties of the associated exponential matrix. Recently, to overcome the stability issues associated with the method of false transients, a perturbation approach was proposed which was found to be more robust than standard method of false transients for a wide range of elliptic PDEs.
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Molecular dynamics generates a path as a set of (rt, pt) at discrete times t in [0,T] where T is the length of the path. For a transition from A to B, (r0, p0) is in A, and (rT, pT) is in B. One of the path times is chosen at random, the momenta p are modified slightly into p + δp, where δp is a random perturbation consistent with system constraints, e.g. conservation of energy and linear and angular momentum. A new trajectory is then simulated from this point, both backward and forward in time until one of the states is reached.
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The larger the perturbation they experience, the farther the halteres move from their original linear path. During these periods, the haltere is no longer moving in only two directions (up and down), but four (up, down, left, and right). The force exerted on the halteres in response to this left right movement is known as Coriolis force and can be produced when any moving object is rotated in the three directions of rotation, yaw, pitch or roll (see figure). When this occurs, tiny bell-shaped structures at the base of the haltere experience strain as the haltere stalk bends in their direction.
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The trajectory Belbruno and Miller developed for Hiten used Weak Stability Boundary Theory and required only a small perturbation to the elliptical swing-by orbit, sufficiently small to be achievable by the spacecraft's thrusters. This course would result in the probe being captured into temporary lunar orbit using zero (called a ballistic transfer), but required five months instead of the usual three days for a Hohmann transfer orbit. This was the first time a satellite had used low- energy transfer to transfer to a Moon orbit. On October 2, 1991, Hiten was captured temporarily into lunar orbit.
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It was also found to have an unusually long period of rotation of 418 hours. On June 27, 1997, the NEAR Shoemaker spacecraft passed within 1,212 km of Mathilde while moving at a velocity of 9.93 km/s. This close approach allowed the spacecraft to capture over 500 images of the surface, and provided data for more accurate determinations of the asteroid's dimensions and mass (based on gravitational perturbation of the spacecraft). However, only one hemisphere of Mathilde was imaged during the fly-by. This was only the third asteroid to be imaged from a nearby distance, following 951 Gaspra and 243 Ida.
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Makemake is a classical Kuiper belt object (KBO), which means its orbit lies far enough from Neptune to remain stable over the age of the Solar System. Unlike plutinos, which can cross Neptune's orbit due to their 2:3 resonance with the planet, the classical objects have perihelia further from the Sun, free from Neptune's perturbation. Such objects have relatively low eccentricities (e below 0.2) and orbit the Sun in much the same way the planets do. Makemake, however, is a member of the "dynamically hot" class of classical KBOs, meaning that it has a high inclination compared to others in its population.
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The Synod rejected the teachings of the Remonstrants on the controverted points as falling outside the bounds of the Reformed confessions. There followed the political condemnation of the statesman Johan van Oldenbarnevelt who had been the protector of the Remonstrants. For the crime of general perturbation in the state of the nation, both in Church and State (treason), he was beheaded on 13 May 1619, only four days after the final meeting of the Synod. As consequence of the Arminian defeat, the jurist Hugo Grotius was given a life sentence in prison; but he escaped with the help of his wife.
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The non- critical string is not formulated with the critical dimension, but nonetheless has vanishing Weyl anomaly. A worldsheet theory with the correct central charge can be constructed by introducing a non-trivial target space, commonly by giving an expectation value to the dilaton which varies linearly along some spacetime direction. For this reason non-critical string theory is sometimes called the linear dilaton theory. Since the dilaton is related to the string coupling constant, this theory contains a region where the coupling is weak (and so perturbation theory is valid) and another region where the theory is strongly coupled.
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DNP was first realized using the concept of the Overhauser effect, which is the perturbation of nuclear spin level populations observed in metals and free radicals when electron spin transitions are saturated by microwave irradiation. This effect relies on stochastic interactions between an electron and a nucleus. The 'dynamic' initially meant to highlight the time-dependent and random interactions in this polarization transfer process. The DNP phenomenon was theoretically predicted by Albert Overhauser in 1953 and initially drew some criticism from Norman Ramsey, Felix Bloch and other renowned physicists of the time on the grounds of being "thermodynamically improbable".
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The tendency of gray bats to form large colonies made the gray bat especially vulnerable to population decline due to both intentional and unintentional human disturbance. While gray bat habitat locations were always ‘patchy,’ gray bat habitats have become increasingly more isolated and fragmented with human perturbation. Suspected factors contributing to species decline include impoundment of waterways (the creation of dams, which causes flooding in former bat caves), cave commercialization, natural flooding, pesticides, water pollution and siltation, and local deforestation. All North American bat species classified as endangered or threatened by the US. Fish and Wildlife service are cave dwelling species.
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The sources, consequences, and control of noise are major questions in study of developmental noise. Recent studies suggest that this noise has multiple sources, including the stochastic or inherently random nature of the biochemical reactions of gene expression. But the detailed mechanisms are still unclear and the contributions of factors such as microRNAs, whose existence was first discovered in the 1990s, remain unclear. For example, one recent study showed that microRNAs can serve different roles, from using noise to throw a developmental switch to buffering the consequences of noise in order to confer robustness to environmental perturbation.
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Hartree–Fock, coupled cluster, many-body perturbation theory (to any order), and full configuration interaction (CI) are size extensive but not always size consistent. For example, the Restricted Hartree–Fock model is not able to correctly describe the dissociation curves of H2 and therefore all post HF methods that employ HF as a starting point will fail in that matter (so-called single-reference methods). Sometimes numerical errors can cause a method that is formally size-consistent to behave in a non-size-consistent manner. Core- extensivity is yet another related property, which extends the requirement to the proper treatment of excited states.
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As described by quantum chromodynamics, the strong interaction between quarks is mediated by gluons, massless vector gauge bosons. Each gluon carries one color charge and one anticolor charge. In the standard framework of particle interactions (part of a more general formulation known as perturbation theory), gluons are constantly exchanged between quarks through a virtual emission and absorption process. When a gluon is transferred between quarks, a color change occurs in both; for example, if a red quark emits a red–antigreen gluon, it becomes green, and if a green quark absorbs a red–antigreen gluon, it becomes red.
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The clumpy structure of the dust belt may be explained by gravitational perturbation from a planet, dubbed Epsilon Eridani b. The clumps in the dust occur at orbits that have an integer resonance with the orbit of the suspected planet. For example, the region of the disk that completes two orbits for every three orbits of a planet is in a 3:2 orbital resonance. In computer simulations the ring morphology can be reproduced by the capture of dust particles in 5:3 and 3:2 orbital resonances with a planet that has an orbital eccentricity of about 0.3.
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The Florida Keys and Miami Hurricane of 1906 This hurricane originated on October 4 near Barbados as a "cyclonic perturbation"; however, no closed circulation was evidently associated with the system. Barometric pressures began sinking in Panama as the system drifted westward, and it was considered a tropical storm by October 8. As the storm headed west, it rapidly strengthened; the storm became a hurricane on October 9 and intensified into a major hurricane on October 10. As it began to curve northwestward, the hurricane made landfall in Nicaragua, and weakened to a tropical storm on October 11.
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Subsequently, the existence of the fixed point found within the Einstein–Hilbert truncation has been confirmed in subspaces of successively increasing complexity. The next step in this development was the inclusion of an R^2-term in the truncation ansatz. This has been extended further by taking into account polynomials of the scalar curvature R (so-called f(R)-truncations), and the square of the Weyl curvature tensor.The contact to perturbation theory is established in: Also, f(R) theories have been investigated in the Local Potential Approximation finding nonperturbative fixed points in support of the Asymptotic Safety scenario.
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The adiabatic theorem is a concept in quantum mechanics. Its original form, due to Max Born and Vladimir Fock (1928), was stated as follows: :A physical system remains in its instantaneous eigenstate if a given perturbation is acting on it slowly enough and if there is a gap between the eigenvalue and the rest of the Hamiltonian's spectrum. In simpler terms, a quantum mechanical system subjected to gradually changing external conditions adapts its functional form, but when subjected to rapidly varying conditions there is insufficient time for the functional form to adapt, so the spatial probability density remains unchanged.
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An initial postural reaction on exposure to an external perturbations was shown to be generated by the brainstem and spinal cord in animal and human studies (short latency mono or polysynaptic spinal loop 40-65ms) Bove, M., Nardone, A., & Schieppati, M. (2003). Effects of leg muscle tendon vibration on group Ia and group II reflex responses to stance perturbation in humans. J Physiol, 550(Pt 2), 617-630. doi:10.1113/jphysiol.2003.043331 followed by the later part of the reaction which is modified by direct transcortical loops (long latency loops, ~132ms).Ackermann, H., Diener, H. C., & Dichgans, J. (1987).
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This effect is the cause of the circular ripples around the impurity. N.B. Where classically near the charged perturbation an overwhelming number of oppositely charged particles can be observed, in the quantum mechanical scenario of Friedel oscillations periodic arrangements of oppositely charged fermions followed by spaces with same charged regions. In the figure to the right, a 2-dimensional Friedel Oscillations has been illustrated with an STM image of a clean surface. As the image is taken on a surface, the regions of low electron density leave the atomic nuclei ‘exposed’ which result in a net positive charge.
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This rapidly expanding field complements the huge progress made in genomics and proteomics, all of which constitute the family of systems biology. Lipidomics research involves the identification and quantification of the thousands of cellular lipid molecular species and their interactions with other lipids, proteins, and other metabolites. Investigators in lipidomics examine the structures, functions, interactions, and dynamics of cellular lipids and the changes that occur during perturbation of the system. Han and Gross first defined the field of lipidomics through integrating the specific chemical properties inherent in lipid molecular species with a comprehensive mass spectrometric approach.
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The principle behind the Regge theory hypothesis (also called analyticity of the second kind or the bootstrap principle) is that all strongly interacting particles lie on Regge trajectories. This was considered the definitive sign that all the hadrons are composite particles, but within S-matrix theory, they are not thought of as being made up of elementary constituents. The Regge theory hypothesis allowed for the construction of string theories, based on bootstrap principles. The additional assumption was the narrow resonance approximation, which started with stable particles on Regge trajectories, and added interaction loop by loop in a perturbation series.
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The horizontal axis illustrates their average distance from Jupiter, the vertical axis their orbital inclination, and the circles their relative sizes. This diagram offers a wider field of view than the previous one, showing other small satellites clustered near the core Ananke group. 1Osculating orbital parameters of irregular satellites of Jupiter change widely in short intervals due to heavy perturbation by the Sun. For example, changes of as much as 1 Gm in semi-major axis in 2 years, 0.5 in eccentricity in 12 years, and as much as 5° in 24 years have been reported.
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The subject of divergent series, as a domain of mathematical analysis, is primarily concerned with explicit and natural techniques such as Abel summation, Cesàro summation and Borel summation, and their relationships. The advent of Wiener's tauberian theorem marked an epoch in the subject, introducing unexpected connections to Banach algebra methods in Fourier analysis. Summation of divergent series is also related to extrapolation methods and sequence transformations as numerical techniques. Examples of such techniques are Padé approximants, Levin-type sequence transformations, and order-dependent mappings related to renormalization techniques for large-order perturbation theory in quantum mechanics.
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The resulting beam has a larger diameter, and hence a lower divergence. Divergence of a laser beam may be reduced below the diffraction of a Gaussian beam or even reversed to convergence if the refractive index of the propagation media increases with the light intensity. This may result in a self-focusing effect. When the wave front of the emitted beam has perturbations, only the transverse coherence length (where the wave front perturbation is less than 1/4 of the wavelength) should be considered as a Gaussian beam diameter when determining the divergence of the laser beam.
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Ross is known for his contributions to the development and exploitation of gauge theories, both within and beyond the Standard Model of particle physics. His work has led to the understanding of the renormalisation structure of spontaneously broken theories and to the theoretical properties of the perturbation series in non-Abelian theories. He performed a number of the early perturbative calculations which helped establish quantum chromodynamics as the theory of the strong nuclear force. Among his contributions to physics beyond the Standard Model was the demonstration that the non-observation of proton decay excluded the simplest Grand Unified Theory.
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Here, the electrons are modelled as a Fermi gas, a gas of particles which obey the quantum mechanical Fermi–Dirac statistics. The free electron model gave improved predictions for the heat capacity of metals, however, it was unable to explain the existence of insulators. The nearly free electron model is a modification of the free electron model which includes a weak periodic perturbation meant to model the interaction between the conduction electrons and the ions in a crystalline solid. By introducing the idea of electronic bands, the theory explains the existence of conductors, semiconductors and insulators.
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Under normal circumstances, even polar materials do not display a net dipole moment. As a consequence there are no electric dipole equivalents of bar magnets because the intrinsic dipole moment is neutralized by "free" electric charge that builds up on the surface by internal conduction or from the ambient atmosphere. Polar crystals only reveal their nature when perturbed in some fashion that momentarily upsets the balance with the compensating surface charge. Spontaneous polarization is temperature dependent, so a good perturbation probe is a change in temperature which induces a flow of charge to and from the surfaces.
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Some authors, in particular with respect to modelling business systems, use negative to refer to the reduction in difference between the desired and actual behavior of a system. John D.Sterman, Business Dynamics: Systems Thinking and Modeling for a Complex World McGraw Hill/Irwin, 2000. In a psychology context, on the other hand, negative refers to the valence of the feedback – attractive versus aversive, or praise versus criticism. In contrast, positive feedback is feedback in which the system responds so as to increase the magnitude of any particular perturbation, resulting in amplification of the original signal instead of stabilization.
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Chiron is classified as a centaur, the first of a class of objects orbiting between the outer planets. Chiron is a Saturn–Uranus object because its perihelion lies in Saturn's zone of control and its aphelion lies in that of Uranus. Centaurs are not in stable orbits and will be removed by gravitational perturbation by the giant planets over a period of millions of years, moving to different orbits or leaving the Solar System altogether. Chiron is probably a refugee from the Kuiper belt and will probably become a short-period comet in about a million years.
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While the effects mediated by CB1, mostly in the central nervous system, have been thoroughly investigated, those mediated by CB2 are not equally well defined. Prenatal cannabis exposure (PCE) has been shown to perturb the fetal endogenous cannabinoid signaling system. This perturbation has not been shown to directly affect neurodevelopment nor cause lifelong cognitive, behavioral, or functional abnormalities, but it may predispose offspring to abnormalities in cognition and altered emotionality from post-natal factors. Additionally, PCE may alter the wiring of brain circuitry in foetal development and cause significant molecular modifications to neurodevelopmental programs that may lead to neurophysiological disorders and behavioural abnormalities.
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In the second edition, Goldstein corrected all the errors that had been pointed out, added a new chapter on perturbation theory, a new section on Bertrand's theorem, and another on Noether's theorem. Other arguments and proofs were simplified and supplemented. Before the death of its primary author in 2005, a new (third) edition of the book was released, with the collaboration of Charles P. Poole and John L. Safko from the University of South Carolina. In the third edition, the book discusses at length various mathematically sophisticated reformations of Newtonian mechanics, namely analytical mechanics, as applied to particles, rigid bodies and continua.
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The 250-680 nm spectral domain is used for the determination of O3, NO2, NO3−, aerosols and temperature. In addition, two high spectral resolution channels centred at 760 and 940 nm allow measurements of O2 and H2O and two fast photometers are used to correct star scintillation perturbations and to determine high vertical resolution temperature profiles. Global latitude coverage is obtained with up to 40 stellar occultations per orbit from South Pole to North Pole. Data acquired on dark limb (night-time) are of better quality than on bright limb (day-time) because of a smaller perturbation by background light.
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Although commonly attributed to the paper in which Kondo model was obtained from the Anderson impurity model by J.R. Schrieffer and P.A. Wolff., Joaquin Mazdak Luttinger and Walter Kohn used this method in an earlier work about non-periodic k·p perturbation theory . Using the Schrieffer–Wolff transformation, the high energy charge excitations present in Anderson impurity model are projected out and a low energy effective Hamiltonian is obtained which has only virtual charge fluctuations. For the Anderson impurity model case, the Schrieffer–Wolff transformation showed that Kondo model lies in the strong coupling regime of the Anderson impurity model.
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String theory is usually formulated with perturbation theory around a fixed background. While it is possible that the theory defined this way is locally background-invariant, if so, it is not manifest, and it is not clear what the exact meaning is. One attempt to formulate string theory in a manifestly background-independent fashion is string field theory, but little progress has been made in understanding it. Another approach is the conjectured, but yet unproven AdS/CFT duality, which is believed to provide a full, non-perturbative definition of string theory in spacetimes with anti-de Sitter asymptotics.
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An ecosystem is said to possess ecological stability (or equilibrium) if it is capable of returning to its equilibrium state after a perturbation (a capacity known as resilience) or does not experience unexpected large changes in its characteristics across time. Although the terms community stability and ecological stability are sometimes used interchangeably, community stability refers only to the characteristics of communities. It is possible for an ecosystem or a community to be stable in some of their properties and unstable in others. For example, a vegetation community in response to a drought might conserve biomass but lose biodiversity.
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Observations from the James Clerk Maxwell Telescope in 1997 revealed an "elongated bright central region" that peaked at 9″ () to the northeast of Vega. This was hypothesized as either a perturbation of the dust disk by a planet or else an orbiting object that was surrounded by dust. However, images by the Keck telescope had ruled out a companion down to magnitude 16, which would correspond to a body with more than 12 times the mass of Jupiter. Astronomers at the Joint Astronomy Centre in Hawaii and at UCLA suggested that the image may indicate a planetary system still undergoing formation.
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Met Éireann issued nationwide orange wind and marine alerts for winds of with gusts of . The UK Met Office issued national severe weather warnings for wind and rain across southwest and northern areas of the UK for the 23 and 24 December. Forty to sixty millimetres of rain was expected across southern England and Wales on 23 December, with gales and severe gales with gusts of gusts and blizzards over the Scottish mountains on 24 December. The storm was described as a "perturbation tempétueuse" (stormy disturbance) by Météo France, who issued orange warnings to parts of Brittany on 22 December.
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Self-propelled particles (SPP), also referred to as the Vicsek model, was introduced in 1995 by Vicsek et al. as a special case of the boids model introduced in 1986 by Reynolds. A swarm is modelled in SPP by a collection of particles that move with a constant speed but respond to a random perturbation by adopting at each time increment the average direction of motion of the other particles in their local neighbourhood. SPP models predict that swarming animals share certain properties at the group level, regardless of the type of animals in the swarm.
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In contrast to the Claisen rearrangement, Cope rearrangements without strain release or electronic perturbation are often close to thermally neutral, and may therefore reach only partial conversion due to an insufficiently favorable equilibrium constant. In the case of hexa-1,5-diene, the rearrangement is degenerate (the product is identical to the starting material), so K = 1 by necessity. 176x176px In asymmetric dienes one often needs to consider the stereochemistry, which in the case of pericyclic reactions, such as the Cope rearrangement, can be predicted with the Woodward-Hoffmann rules and consideration of the preference for the chair transition state geometry.
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Lee's research group develops and applies methods such as lattice effective field theory to study superfluidity, nuclear clustering, nuclear structure from first principles, and quantum scattering and reactions. Some of the techniques include spherical wall methods for scattering on a lattice, impurity lattice Monte Carlo for quantum impurities, adiabatic projection method for nuclear scattering and reactions, pinhole algorithm for nuclear structure, pinhole trace algorithm for thermodynamics, and eigenvector continuation method for quantum correlations beyond perturbation theory. Lee worked with collaborators Evgeny Epelbaum, Hermann Krebs, and Ulf-G. Meißner, to perform the first ab initio calculations of the Hoyle state of carbon-12.
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General Atomic and Molecular Electronic Structure System (GAMESS-UK) is a computer software program for computational chemistry. The original code split in 1981 into GAMESS-UK and GAMESS (US) variants, which now differ significantly. Many of the early developments in the UK version arose from the earlier UK based ATMOL program, which, unlike GAMESS, lacked analytical gradients for geometry optimisation. GAMESS-UK can perform many general computational chemistry calculations, including Hartree–Fock method, Møller–Plesset perturbation theory (MP2 & MP3), coupled cluster (CCSD & CCSD(T)), density functional theory (DFT), configuration interaction (CI), and other advanced electronic structure methods.
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However, the spheromak does experience the "tilting perturbation" that allows it to rotate within the confinement area. This can be addressed with external magnets, but more often the confinement area is wrapped in a (typically copper) conductor. When the edge of the spheromak torus approaches the conductive surface, a current is induced into it that, following Lenz's law, reacts to push the spheromak back into the center of the chamber. It is also possible to get the same effect with a single conductor running down the center of the chamber, through the "hole" in the center of the spheromak.
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Any nucleus with more than one unpaired nuclear particle (protons or neutrons) will have a charge distribution which results in an electric quadrupole moment. Allowed nuclear energy levels are shifted unequally due to the interaction of the nuclear charge with an electric field gradient supplied by the non-uniform distribution of electron density (e.g. from bonding electrons) and/or surrounding ions. As in the case of NMR, irradiation of the nucleus with a burst of RF electromagnetic radiation may result in absorption of some energy by the nucleus which can be viewed as a perturbation of the quadrupole energy level.
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Most perceptions of heartbeat sensations usually occur during a time of homeostatic perturbation, such as when the state of the body changes from external or internal influences such as physical exertion or elevated arousal states (e.g., riding a roller coaster, watching a scary movie, public speaking anxiety, or having a panic attack). For this reason, cardiac interoception is also sometimes studied by inducing perturbations of bodily state. This can be done pharmacologically using adrenaline-like drugs, such as isoproterenol, which mimics activation of the sympathetic nervous system, resulting in increased heart rate and respiration rate, similar to the “fight-or-flight” response.
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The first detection of a Coronal mass ejection (CME) as such was made on Dec 1 1971 by R. Tousey of the US Naval Research Laboratory using the 7th Orbiting Solar Observatory (OSO 7). Earlier observations of coronal transients or even phenomena observed visually during solar eclipses are now understood as essentially the same thing. The largest geomagnetic perturbation, resulting presumably from a "prehistoric" CME, coincided with the first-observed solar flare, in 1859. The flare was observed visually by Richard Christopher Carrington and the geomagnetic storm was observed with the recording magnetograph at Kew Gardens.
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Nottale began his professional work in the domain of general relativity. He defended his PhD Thesis in June 1980, entitled "Perturbation of the Hubble relation by clusters of galaxies", in which he showed that clusters of galaxies as a whole may act as gravitational lenses on distant sources.in French: "Les lentilles gravitationnelles par amas de galaxies" Some of these results were reported in Nature. He also published a popular book L'Univers et la Lumière, Flammarion, Nouvelle Bibliothèque Scientifique 1994, Champs 1998) for which he received a prize in 1995 (Prix du livre d'Astronomie Haute-Maurienne-Vanoise).
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Molecular reorientation or tumbling can then modulate these orientation-dependent spin interaction energies. According to quantum mechanics, time-dependent interaction energies cause transitions between the nuclear spin states which result in nuclear spin relaxation. The application of time-dependent perturbation theory in quantum mechanics shows that the relaxation rates (and times) depend on spectral density functions that are the Fourier transforms of the autocorrelation function of the fluctuating magnetic dipole interactions.A. Abragam "Principles of Nuclear Magnetism" (Oxford University Press, 1961) The form of the spectral density functions depend on the physical system, but a simple approximation called the BPP theory is widely used.
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A significant second-order effect on the Perturbation Molecular Orbital model of homoaromaticity is the addition of a second homoconjugate linkage and its influence on stability. The effect is often a doubling of the instability brought about by the addition of a single homoconjugate linkage, although there is an additional term that depends on the proximity of the two linkages. In order to minimize δβ and thus keep the coupling term to a minimum, bishomoaromatic compounds form depending on the conformation of greatest stability by resonance and smallest steric hindrance. The synthesis of the 1,3-bishomotropenylium cation by protonating cis- bicyclo[6.1.
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Several recent studies have provided evidence that loss-of-function mutations in pre-synaptic proteins of the photoreceptor cells ribbon synapse can cause X-linked congenital stationary night blindness (CSNB) through mutations in the CACNA1F gene, which codes for the αF1-subunit of the L-type calcium channel Cav1.4. The gene is expressed at the active zone of photoreceptor ribbon synapses. The mutation is characterized by a significant reduction in both night and variable perturbation of daylight vision. The mutations in CACNA1F and Cav1.4 have also been observed to co- localize with CaBP4, a photoreceptor-specific calcium-binding protein.
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The first subset is homeomorphic to Ω(f) via a homeomorphism h which conjugates the restriction of f to Ω(f) with the restriction of fε to Ω1: : f_\epsilon\circ h(x)=h\circ f(x), \quad \forall x\in \Omega(f). If Ω2 is empty then h is onto Ω(fε). If this is the case for every perturbation fε then f is called omega stable. A diffeomorphism f is omega stable if and only if it satisfies axiom A and the no-cycle condition (that an orbit, once having left an invariant subset, does not return).
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Consequently, the interaction may be characterised by a dimensionful parameter , namely the value of the RG scale at which the coupling constant diverges. In the case of quantum chromodynamics, this energy scale is called the QCD scale, and its value 220 MeV supplants the role of the original dimensionless coupling constant in the form of the logarithm (at one- loop) of the ratio and . Perturbation theory, which produced this type of running formula, is only valid for a (dimensionless) coupling ≪ 1. In the case of QCD, the energy scale is an infrared cutoff, such that implies , with the RG scale.
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Milton Denman Van Dyke (August 1, 1922 – May 10, 2010) was Professor of the Department of Aeronautics and Astronautics at Stanford University. He was known for his work in fluid dynamics, especially with respect to the use of perturbation analysis in aerodynamics. His often-cited book An Album of Fluid Motion presents a collection of about 400 selected black-and-white photographs of flow visualization in experiments, received – on his request – from researchers all over the world.Schwartz (2002) Together with Bill Sears, Milton founded the Annual Review of Fluid Mechanics, in 1969, for which he was an editor until 2000.
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The research interests of Prof. V. Koshmanenko concern modeling of complex dynamical systems, fractal geometry, functional analysis, operator theory, mathematical physics. He proposed the construction of wave and scattering operators in terms of bilinear functionals, introduced the notion of singular quadratic form and produced the classification of pure singular quadratic forms, developed the self-adjoint extensions approach to the singular perturbation theory in scales of Hilbert spaces, investigated the direct and inverse negative eigenvalues problem under singular perturbations. Volodymyr Koshmanenko developed the original theory of conflict dynamical systems and built a serious new models of complex dynamical systems with repulsive and attractive interaction.
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Some of his more famous results include solutions for secondary flow in curved tubes, for the perturbation to shear flow near a wall caused by a gap in the wall, and for flow in a corner. Dean was an undergraduate at Trinity College, Cambridge. He spent five years at Imperial College, and was later a fellow of Trinity College. During the war he undertook mathematical work as part of the Anti- Aircraft Experimental Section of M.I.D. He also held the Goldsmid Chair in Applied Mathematics at University College London (from which he retired in 1964), and a chair at the University of Arizona.
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Jean Écalle (born 1950) is a French mathematician, specializing in dynamic systems, perturbation theory, and analysis. Écalle received, in 1974 from the University of Paris-Saclay in Orsay, a doctorate under the supervision of Hubert Delange with Thèse d'État entitled La théorie des invariants holomorphes. He is a directeur de recherché (senior researcher) of the Centre national de la recherche scientifique (CNRS) and is a professor at the University of Paris-Saclay. He developed a theory of so-called "resurgent functions", analytic functions with isolated singularities, which have a special algebra of derivatives (Alien calculus, Calcul différentiel étranger).
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The number of Hungarian schools was rising continuously, as well as the proportion of those in Italian where more and more classes were taught in Hungarian. Finally, in 1912 a "Superior Commercial Academy" was instituted in Fiume, a first step for a planned Hungarian university. Therefore, the ongoing conflict with the Hungarian government reached its height at a time of maximum prosperity and economic development of the "Jewel of the Hungarian Crown". On 20 June 1913 the Governor suspends the Rappresentanza for "opposition to the laws of the State", and for "perturbation" of the "constituted order".
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In breast cancer increased survival is observed in patients displaying a high level of ICR gene expression. This immune active phenotype was associated with an increased level of mutations while the poor immune phenotype was defined by perturbation in the MAPK signalling pathways. The consensus clustering of tumours based on ICR gene expression provides an assessment of the prognosis and response to immunotherapy. To illustrate, classification of breast cancer into four classes (ranking from ICR4 to ICR1) have shown better levels of immune anti-tumour response in ICR4 tumours, as well as a prolonged survival in comparison to ICR1-3 tumours.
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Coronal mass ejections are often associated with other forms of solar activity, but a broadly accepted theoretical understanding of these relationships has not been established. CMEs most often originate from active regions on the Sun's surface, such as groupings of sunspots associated with frequent flares. Near solar maxima, the Sun produces about three CMEs every day, whereas near solar minima, there is about one CME every five days. The largest recorded geomagnetic perturbation, resulting presumably from a CME hitting the Earth's magnetosphere, was the solar storm of 1859 (the Carrington Event), which took down parts of the recently created US telegraph network, starting fires and shocking some telegraph operators.
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Uniaxial extensional flow created within necked filament by a capillary instability The linear stability analysis introduced by Plateau and Rayleigh can be employed to determine a wavelength for which a perturbation on a jet surface is unstable. In this case, the pressure gradient across the free-surface can cause the fluid in the thinnest region to be "squeezed" out towards the swollen bulges, thus creating a strong uniaxial extensional flow in the necked region. As the instability grows and strains become progressively larger, the thinning is governed by non-linear effects. Theoretical considerations on the fluid motion suggested that the behaviour approaching the breakup singularity can be captured using self-similarity.
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But because Feynman propagators are nonlocal in time, translating a field process to a coherent particle language is not completely intuitive, and has only been explicitly worked out in certain special cases. In the case of nonrelativistic bound states, the Bethe–Salpeter equation describes the class of diagrams to include to describe a relativistic atom. For quantum chromodynamics, the Shifman- Vainshtein-Zakharov sum rules describe non-perturbatively excited long- wavelength field modes in particle language, but only in a phenomenological way. The number of Feynman diagrams at high orders of perturbation theory is very large, because there are as many diagrams as there are graphs with a given number of nodes.
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The only fully successful implementation of the program required another assumption to organize the mathematics of unitarity (the narrow resonance approximation). This meant that all the hadrons were stable particles in the first approximation, so that scattering and decays could be thought of as a perturbation. This allowed a bootstrap model with infinitely many particle types to be constructed like a field theory — the lowest order scattering amplitude should show Regge behavior and unitarity would determine the loop corrections order by order. This is how Gabriele Veneziano and many others, constructed string theory, which remains the only theory constructed from general consistency conditions and mild assumptions on the spectrum.
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In most practical problems such as planetary motion, however, the interaction potential energy between two bodies is not exactly an inverse square law, but may include an additional central force, a so-called perturbation described by a potential energy . In such cases, the LRL vector rotates slowly in the plane of the orbit, corresponding to a slow apsidal precession of the orbit. By assumption, the perturbing potential is a conservative central force, which implies that the total energy and angular momentum vector L are conserved. Thus, the motion still lies in a plane perpendicular to L and the magnitude is conserved, from the equation .
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Arnold's research has focused on label-free detection of bio-nanoparticles from the perturbation of the resonant frequency of a microcavity, after estimating the extreme sensitivity of such an approach for DNA sensing in a 2001 American Scientist article. In 2003, he and his co-workers identified the mechanism for the detection of individual protein and viruses. The recipe for the detection and sizing of single HIV viruses following this mechanism was proposed early in 2008 at a Faraday Discussion of the Royal Society of Chemistry. Later that year, this recipe was applied to the detection and sizing of comparably sized single Influenza virus particles.
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In principle, such methods may be applied to any system, given sufficient computer resources, and may address fundamental questions such as naked singularities. Approximate solutions may also be found by perturbation theories such as linearized gravityFor instance and its generalization, the post-Newtonian expansion, both of which were developed by Einstein. The latter provides a systematic approach to solving for the geometry of a spacetime that contains a distribution of matter that moves slowly compared with the speed of light. The expansion involves a series of terms; the first terms represent Newtonian gravity, whereas the later terms represent ever smaller corrections to Newton's theory due to general relativity.
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In all cases, the pools overlie acidic igneous rocks, and they are usually mineral-poor and retain some moisture in the sediment when they dry out. Like all Anostraca, T. stagnalis is a filter feeder, removing microplankton, microorganisms and other organic material from suspension with its bristly phyllopodia. Tanymastix stagnalis is sensitive to changes in the intensity of light, and respond to sudden shade by swimming towards the bottom of the pool, or even burying themselves in the sediment. The main threat to them is perturbation of the habitat, in particular the introduction of predators such as the fishes Lepomis gibbosus and Gambusia affinis.
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The classification of traditional coupled-cluster methods rests on the highest number of excitations allowed in the definition of T. The abbreviations for coupled-cluster methods usually begin with the letters "CC" (for "coupled cluster") followed by # S – for single excitations (shortened to singles in coupled-cluster terminology), # D – for double excitations (doubles), # T – for triple excitations (triples), # Q – for quadruple excitations (quadruples). Thus, the T operator in CCSDT has the form : T = T_1 + T_2 + T_3. Terms in round brackets indicate that these terms are calculated based on perturbation theory. For example, the CCSD(T) method means: # Coupled cluster with a full treatment singles and doubles.
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Dr. Stanley Wyatt joined the faculty in 1953, George Swenson and Ivan King in 1956, Kennth Yoss, John Dickel and James Kaler in 1964 and Edward Olson in 1966. With George Swenson's arrival, Illinois began a program of radio astronomy resulting in the Vermillion River Radio Observatory that opened in 1962. Prairie Observatory was an optical observatory consisting of a 40-inch telescope and was completed in 1967. By the time of Dr. McVittie's retirement in 1971, the one-astronomer department had expanded to nine faculty with research interests in relativity, cosmology, celestial mechanics, perturbation theory, dynamics of star clusters, planetary nebulae, planets, supernovae and radio astronomy.
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The horseshoe form of the vortex system was recognized by the British aeronautical pioneer Lanchester in 1907.Lanchester (1907) Given the distribution of bound vorticity and the vorticity in the wake, the Biot–Savart law (a vector-calculus relation) can be used to calculate the velocity perturbation anywhere in the field, caused by the lift on the wing. Approximate theories for the lift distribution and lift-induced drag of three-dimensional wings are based on such analysis applied to the wing's horseshoe vortex system.Milne-Thomson (1966), Section 10.1Clancy (1975), Section 8.9 In these theories, the bound vorticity is usually idealized and assumed to reside at the camber surface inside the wing.
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In the theory of critical phenomena, free energy of a system near the critical point depends analytically on the coefficients of generic (not dangerous) irrelevant operators, while the dependence on the coefficients of dangerously irrelevant operators is non-analytic ( p. 49). The presence of dangerously irrelevant operators leads to the violation of the hyperscaling relation \alpha=2-d u between the critical exponents \alpha and u in d dimensions. The simplest example ( p. 93) is the critical point of the Ising ferromagnet in d\ge4 dimensions, which is a gaussian theory (free massless scalar \phi), but the leading irrelevant perturbation \phi^4 is dangerously irrelevant.
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Hangar One where Lockheed Missiles and Space Company was under contract to construct the first nuclear stage rocket engine. In 1956 Sachs became a Senior Scientist at Lockheed Missiles and Space Laboratory, Based in Sunnyvale and adjacent to the NASA-Marshall Space Flight Center, Moffett Field, Lockheed Martin Missiles and Space Systems was and continues to be one of the most important satellite development and manufacturing plants in the United States, covering 412 acres. While at Lockheed Sachs began developing with Solomon Schwebel a field theory of quantum electrodynamics that included broken symmetries that did not require recourse to renormalization or perturbation techniques – the "Schwebel-Sachs" model.
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As evidenced by Efimov and Ganbold in an earlier work (Efimov 1991), the procedure of tadpole renormalization can be employed very effectively to remove the divergences from the action of the basic field-theoretic representation of the partition function and leads to an alternative functional integral representation, called the Gaussian equivalent representation (GER). They showed that the procedure provides functional integrals with significantly ameliorated convergence properties for analytical perturbation calculations. In subsequent works Baeurle et al. developed effective low-cost approximation methods based on the tadpole renormalization procedure, which have shown to deliver useful results for prototypical polymer and PE solutions (Baeurle 2006a, Baeurle 2006b, Baeurle 2007a).
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Kane used the k·p perturbation method to determine what became known as the Kane model or Kane Hamiltonian of the structure of energy bands of semiconductors. The Kane Hamiltonian describes the valence and conduction bands in sp3 bonded semiconductors: the group IV, II-V and II-VI semiconductors. This 1957 publication is still prominent in scientific literature and textbooks more than 50 years after its discovery (the paper has about 3377 citations despite the fact that modern citation indexes undercount citations for papers published before the mid-1990s). The model is now often cited via books where it is discussed, most notably in Yu's and Cardona's book, Fundamentals of Semiconductors.
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If a perturbation set the system into motion somehow, the object would pick up speed exponentially in time, not quadratically. Standing on the surface of the Moon in 1971, David Scott famously repeated Galileo's experiment by dropping a feather and a hammer from each hand at the same time. In the absence of a substantial atmosphere, the two objects fell and hit the Moon's surface at the same time. The first convincing mathematical theory of gravity – in which two masses are attracted toward each other by a force whose effect decreases according to the inverse square of the distance between them – was Newton's law of universal gravitation.
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As one of the first collaborators of Manfred Eigen, who had been appointed as a department director at the institute in 1953, De Maeyer became deeply involved in a new approach to the study of very fast chemical processes, which was based on the measurement of chemical relaxation phenomena during the return to equilibrium after a physically induced perturbation of a chemical system.Salvatore Califano, Pathways to Modern Chemical Physics, p.260, (2012) In 1955 Eigen and De Maeyer succeeded in measuring the reaction rate and the mechanism of neutralization reaction H+ \+ OH– = H2O for the first time, supposedly the fastest reaction known. Up until then this was thought to be impossible.
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A major application of Walsh diagrams is to explain the regularity in structure observed for related molecules having identical numbers of valence electrons (e.g. why H2O and H2S look similar), and to account for how molecules alter their geometries as their number of electrons or spin state changes. Additionally, Walsh diagrams can be used to predict distortions of molecular geometry from knowledge of how the LUMO (Lowest Unoccupied Molecular Orbital) affects the HOMO (Highest Occupied Molecular Orbital) when the molecule experiences geometrical perturbation. Walsh's rule for predicting shapes of molecules states that a molecule will adopt a structure that best provides the most stability for its HOMO.
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Some antiferromagnetic materials exhibit a non-zero magnetic moment at a temperature near absolute zero. This effect is ascribed to spin canting, a phenomenon through which spins are tilted by a small angle about their axis rather than being exactly co-parallel. Antisymmetric exchange would align spins perpendicular to each other Spin canting is due to two factors contrasting each other: isotropic exchange would align the spins exactly antiparallel, while antisymmetric exchange arising from relativistic effects (spin-orbit coupling) would align the spins at 90° to each other. The net result is a small perturbation, the extent of which depends on the relative strength of these effects.
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Attempts to overcome this fundamental limitation using low frequency coils and superconducting magnetic field sensors have not led to widespread applications. A recent technique, referred to as Lorentz force eddy current testing (LET), exploits the advantages of applying DC magnetic fields and relative motion providing deep and relatively fast testing of electrically conducting materials. In principle, LET represents a modification of the traditional eddy current testing from which it differs in two aspects, namely (i) how eddy currents are induced and (ii) how their perturbation is detected. In LET eddy currents are generated by providing the relative motion between the conductor under test and a permanent magnet (see figure 10).
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Meanwhile, through the Transport Coordination Board, Union Airways with its commercially strong backing blocked and continued to block the other airline, Great Pacific, from landing at Palmerston North leaving the Gisborne-Hawkes Bay feeder airlines with a restricted service. Their passengers would have to travel north by rail. Union Airways under their postal contract collected mail from the overnight Limited Express train at Palmerston and took it to the South Island and required no air link to Auckland.Trunk Air Services, free development Evening Post, 8 August 1935, page 10 The board "caused perturbation" in the North Island by noting the most important trunk route would be between Palmerston North and Dunedin.
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Much of the difficulty, and many of the disputes, in understanding the large-scale structure of the universe can be resolved by better understanding the choice of gauge in general relativity. By the scalar-vector-tensor decomposition, the metric includes four scalar perturbations, two vector perturbations, and one tensor perturbation. Only the scalar perturbations are significant: the vectors are exponentially suppressed in the early universe, and the tensor mode makes only a small (but important) contribution in the form of primordial gravitational radiation and the B-modes of the cosmic microwave background polarization. Two of the four scalar modes may be removed by a physically meaningless coordinate transformation.
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This approach to perturbation theory produces differential equations that are of just the right order needed to describe the true physical degrees of freedom and as such no non-physical gauge modes exist. It is usual to express the theory in a coordinate free manner. For applications of kinetic theory, because one is required to use the full tangent bundle, it becomes convenient to use the tetrad formulation of relativistic cosmology. The application of this approach to the computation of anisotropies in cosmic microwave background radiation requires the linearization of the full relativistic kinetic theory developed by Thorne (1980) and Ellis, Matravers and Treciokas (1983).
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The waves are interpreted as a spiral pattern of vertical corrugations of 2 to 20 m amplitude; the fact that the period of the waves is decreasing over time (from 60 km in 1995 to 30 km by 2006) allows a deduction that the pattern may have originated in late 1983 with the impact of a cloud of debris (with a mass of ≈1012 kg) from a disrupted comet that tilted the rings out of the equatorial plane. A similar spiral pattern in Jupiter's main ring has been attributed to a perturbation caused by impact of material from Comet Shoemaker-Levy 9 in 1994.
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The experimental confirmation by Carver and Slichter as well as an apologetic letter from Ramsey both reached Overhauser in the same year.Purdue University Obituary of Albert W. Overhauser The so-called electron-nucleus cross-relaxation, which is responsible for the DNP phenomenon is caused by rotational and translational modulation of the electron-nucleus hyperfine coupling. The theory of this process is based essentially on the second-order time-dependent perturbation theory solution of the von Neumann equation for the spin density matrix. While the Overhauser effect relies on time-dependent electron-nuclear interactions, the remaining polarizing mechanisms rely on time-independent electron-nuclear and electron-electron interactions.
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There are many important implications from the Fluctuation Theorem. One is that small machines (such as nanomachines or even mitochondria in a cell) will spend part of their time actually running in "reverse". What we mean with "reverse" is that it is possible to observe that these small molecular machines are able to generate work by taking heat from the environment. This is possible because there exists a symmetry relation in the work fluctuations associated with the forward and reverse changes a system undergoes as it is driven away from thermal equilibrium by the action of an external perturbation, which is a result predicted by the Crooks fluctuation theorem.
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Cloud feedback is the coupling between cloudiness and surface air temperature where a surface air temperature change leads to a change in clouds, which could then amplify or diminish the initial temperature perturbation. Cloud feedbacks can affect the magnitude of internally generated climate variability or they can affect the magnitude of climate change resulting from external radiative forcings. Global warming is expected to change the distribution and type of clouds. Seen from below, clouds emit infrared radiation back to the surface, and so exert a warming effect; seen from above, clouds reflect sunlight and emit infrared radiation to space, and so exert a cooling effect.
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Until 2000, it was thought that rock sequences spanning the Permian–Triassic boundary were too few and contained too many gaps for scientists to reliably determine its details. However, it is now possible to date the extinction with millennial precision. U–Pb zircon dates from five volcanic ash beds from the Global Stratotype Section and Point for the Permian–Triassic boundary at Meishan, China, establish a high- resolution age model for the extinction – allowing exploration of the links between global environmental perturbation, carbon cycle disruption, mass extinction, and recovery at millennial timescales. The extinction occurred between 251.941 ± 0.037 and 251.880 ± 0.031 Ma ago, a duration of 60 ± 48 ka.
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Data acquisition resumed in late 1967. The cosmic dust detector registered 17 hits in a 15-minute span on September 15, part of an apparent micrometeoroid shower that temporarily changed the spacecraft attitude and probably slightly damaged its thermal shield. Later it was speculated that Mariner 4 passed through debris of D/1895 Q1 (D/Swift), and even made a flyby of that comet's possibly shattered nucleus at 20 million kilometers. On December 7 the gas supply in the attitude control system was exhausted, and between December 10 and 11, a total of 83 micrometeoroid hits were recorded which caused perturbation of the spacecraft's attitude and degradation of the signal strength.
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While Richard A. Young and colleagues identified super-enhancers, Francis Collins and colleagues identified stretch enhancers. Both super-enhancers and stretch enhancers are clusters of enhancers that control cell-specific genes and may be largely synonymous. As currently defined, the term “super-enhancer” was introduced by Young’s lab to describe regions identified in mouse embryonic stem cells (ESCs). These particularly large, potent enhancer regions were found to control the genes that establish the embryonic stem cell identity, including Oct-4, Sox2, Nanog, Klf4, and Esrrb. Perturbation of the super-enhancers associated with these genes showed a range of effects on their target genes’ expression.
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The basic operating principle of Transit is similar to the system used by emergency locator transmitters, except that in the latter case the transmitter is on the ground and the receiver is in orbit. Each Transit system satellite broadcast two UHF carrier signals that provided precise time hacks (every two minutes), plus the satellite's six orbital elements and orbit perturbation variables. The orbit ephemeris and clock corrections were uploaded twice each day to each satellite from one of the four Navy tracking and injection stations. This broadcast information allowed a ground receiver to calculate the location of the satellite at any point in time.
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In biology, constructive development refers to the hypothesis that organisms shape their own developmental trajectory by constantly responding to, and causing, changes in both their internal state and their external environment. Constructive development can be contrasted with programmed development, the hypothesis that organisms develop according to a genetic program or blueprint. The constructivist perspective is found in philosophy, most notably developmental systems theory, and in the biological and social sciences, including developmental psychobiology and key themes of the extended evolutionary synthesis. Constructive development may be important to evolution because it enables organisms to produce functional phenotypes in response to genetic or environmental perturbation, and thereby contributes to adaptation and diversification.
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Such spheres are useful in clustering, where groups of similar data points are classified together. In statistical analysis the scattering of data points within a sphere may be attributed to measurement error or natural (usually thermal) processes, in which case the cluster represents a perturbation of an ideal point. In some circumstances this ideal point may be used as a substitute for the points in the cluster, advantageous in reducing calculation time. In operations research the clustering of values to an ideal point may also be used to reduce the number of inputs in order to obtain approximate values for NP-hard problems in a reasonable time.
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The Vienna Ab initio Simulation Package, better known as VASP, is a package for performing ab initio quantum mechanical calculations using either Vanderbilt pseudopotentials, or the projector augmented wave method, and a plane wave basis set. The basic methodology is density functional theory (DFT), but the code also allows use of post-DFT corrections such as hybrid functionals mixing DFT and Hartree–Fock exchange (e.g. HSE, PBE0 or B3LYP), many-body perturbation theory (the GW method) and dynamical electronic correlations within the random phase approximation. Originally, VASP was based on code written by Mike Payne (then at MIT), which was also the basis of CASTEP.
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With a nearly parabolic trajectory, estimates for the orbital period of this comet have varied from 254,000 to 558,000 years, and even as high as 6.5 million years. (Solution using the Solar System Barycenter. Select Ephemeris Type:Elements and Center:@0) Computing the best-fit orbit for this long-period comet is made more difficult since it underwent a splitting event which may have caused a non-gravitational perturbation of the orbit. The 2008 SAO Catalog of Cometary Orbits shows 195 observations for C/1975 V1 and 135 for C/1975 V1-A, for a combined total of 330 (218 observations were used in the fit).
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Hopfield dielectric – in quantum mechanics a model of dielectric consisting of quantum harmonic oscillators interacting with the modes of the quantum electromagnetic field. The collective interaction of the charge polarization modes with the vacuum excitations, photons leads to the perturbation of both the linear dispersion relation of photons and constant dispersion of charge waves by the avoided crossing between the two dispersion lines of polaritons. Similarly to the acoustic and the optical phonons and far from the resonance one branch is photon-like while the other charge wave-like. Mathematically the Hopfield dielectric for the one mode of excitation is equivalent to the Trojan wave packet in the harmonic approximation.
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Investigations in 2010 and 2011 found that the orbital period of the two stars in UZ Fornacis varied cyclically. Researchers attributed this to two possible gas giant sized planets around the two stars, perturbing their orbits and causing the orbital period to vary. As of 2019, there is not enough information to explain all of the period variations, since the planets would have to be in eccentric orbits to fit the data, and that would cause the orbits to be dynamically unstable. It is possible that there are even more planets causing additional perturbation, or some physical effect such as the Applegate mechanism is responsible for the eclipse timing variations.
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For specific problems effective theories may be written down which give qualitatively correct results in certain limits. In the best of cases, these may then be obtained as systematic expansions in some parameter of the QCD Lagrangian. One such effective field theory is chiral perturbation theory or ChiPT, which is the QCD effective theory at low energies. More precisely, it is a low energy expansion based on the spontaneous chiral symmetry breaking of QCD, which is an exact symmetry when quark masses are equal to zero, but for the u, d and s quark, which have small mass, it is still a good approximate symmetry.
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Spy for Vanity Fair, 1899 Beauchamp succeeded his father in the earldom in 1891 at the age of 18, and was mayor of Worcester between 1895 and 1896. A progressive in his ideas, he was surprised to be offered the post of Governor of New South Wales in May 1899. Though he was good at the job and enjoyed the company of local artists and writers, he was unpopular in the colony for a series of gaffes and misunderstandings, most notably over his reference to the 'birthstain' of Australia's convict origins. His open association with the high church and Anglo-Catholicism caused increased perturbation in the Evangelical Council.
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Insulated neighborhoods are defined as chromosome loops that are formed by CTCF homodimers, co-bound with cohesin, and containing at least one gene. The CTCF/cohesin-bound regions delimiting an insulated neighborhood are called “anchors.” One study in human Embryonic stem cells identified ~13,000 insulated neighborhoods that, on average, each contained three genes and was about 90kb in size. Two lines of evidence argue that the boundaries of insulated neighborhoods are insulating: 1) the vast majority (~90-97%) of enhancer-gene interactions are contained within insulated neighborhoods and 2) genetic perturbation of CTCF/cohesin-bound insulated neighborhood anchors leads to local gene dysregulation due to novel interactions outside of the neighborhood.
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Q-Chem can perform a number of general quantum chemistry calculations, such as Hartree–Fock, density functional theory (DFT) including time-dependent DFT (TDDFT), Møller–Plesset perturbation theory (MP2), coupled cluster (CC), equation-of-motion coupled-cluster (EOM- CC), configuration interaction (CI), algebraic diagrammatic construction (ADC), and other advanced electronic structure methods. Q-Chem also includes QM/MM functionality. Q-Chem 4.0 and higher releases come with the graphical user interface, IQMol, which includes a hierarchical input generator, a molecular builder, and general visualization capabilities (MOs, densities, molecular vibrations, reaction pathways, etc.). IQMol is developed by Andrew Gilbert (in coordination with Q-Chem) and is distributed as free open-source software.
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František Wolf (1904–1989) was a Czech mathematician known for his contributions to trigonometry and mathematical analysis, specifically the study of the perturbation of linear operators. Wolf was born 1904 in Prostějov, then part of the Austro-Hungarian empire and now part of the Czech Republic, the elder of two children of a furniture maker. He studied physics at Charles University in Prague, and then mathematics at Masaryk University in Brno under the supervision of Otakar Borůvka; he was awarded a doctorate in 1928 (degree Rerum Naturum Doctor). He then taught mathematics at the high school level until 1937, when he obtained a faculty position at Charles University.
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TIME Magazine. Again, Masses July 1, 1929 In late December 1930, the Archbishop issued a scathing denunciation of Protestantism in Mexico, claiming, "There is solid ground for believing that North American Protestant sects, moved by political motives, seek to aggravate religious perturbation in Mexico...The names Protestant, Methodist, and Presbyterian fall on Mexicans as a species of stigma because of the marked character of the North American dominion all these Protestants bring to Mexico. Hence the popular opinion that Protestantism is one of the elements upon which a powerful neighboring nation counts to effect slowly but surely domination, hegemony or realization of its imperialism in our land".TIME Magazine.
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In the usual pendulum with a fixed suspension, the only stable equilibrium position is with the bob hanging below the suspension point; the inverted position is a point of unstable equilibrium, and the smallest perturbation moves the pendulum out of equilibrium. In nonlinear control theory the Kapitza pendulum is used as an example of a parametric oscillator that demonstrates the concept of "dynamic stabilization". The pendulum was first described by A. Stephenson in 1908, who found that the upper vertical position of the pendulum might be stable when the driving frequency is fast. Yet until the 1950s there was no explanation for this highly unusual and counterintuitive phenomenon.
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This confirmed the behaviour predicted by the SPP models. In the field, according to the Food and Agriculture Organization of the United Nations, the average density of marching bands is 50 locusts/m2 (50 million locusts/km2), with a typical range from 20 to 120 locusts/m2. The research findings discussed above demonstrate the dynamic instability that is present at the lower locust densities typical in the field, where marching groups randomly switch direction without any external perturbation. Understanding this phenomenon, together with the switch to fully coordinated marching at higher densities, is essential if the swarming of desert locusts is to be controlled.
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The transcript that begins with exon 1B is preferentially induced by hypoxia, resulting in the accumulation of this protein in the endoplasmic reticulum (ER). The protein encoded by this gene is thought to play an important role in protein folding and secretion in the ER. Since suppression of the protein is associated with accelerated apoptosis, it is also suggested to have an important cytoprotective role in hypoxia-induced cellular perturbation. This protein has been shown to be up- regulated in tumors, especially in breast tumors, and thus it is associated with tumor invasiveness. There is also an alternative translation site of this gene which lacks the signal peptide.
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The perturbative expansion associated with this Lagrangian, using the method of functional quantization, is generally referred to as the Rξ gauge. It reduces in the case of an Abelian U(1) gauge to the same set of Feynman rules that one obtains in the method of canonical quantization. But there is an important difference: the broken gauge freedom appears in the functional integral as an additional factor in the overall normalization. This factor can only be pulled out of the perturbative expansion (and ignored) when the contribution to the Lagrangian of a perturbation along the gauge degrees of freedom is independent of the particular "physical" field configuration.
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To describe this forward-and-backward motion, Apollonius of Perga () developed the concept of deferents and epicycles, according to which the planets are carried on rotating circles that are themselves carried on other rotating circles, and so on. Any orbit can be described with a sufficient number of judiciously chosen epicycles, since this approach corresponds to a modern Fourier transform.Sugon QM, Bragais S, McNamara DJ (2008) Copernicus’s epicycles from Newton’s gravitational force law via linear perturbation theory in geometric algebra . Roughly 350 years later, Claudius Ptolemaeus published his Almagest, in which he developed this system to match the best astronomical observations of his era.
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A perturbation of nuclear spin orientations from equilibrium will occur only when an oscillating magnetic field is applied whose frequency νrf sufficiently closely matches the Larmor precession frequency νL of the nuclear magnetization. The populations of the spin-up and -down energy levels then undergo Rabi oscillations, which are analyzed most easily in terms of precession of the spin magnetization around the effective magnetic field in a reference frame rotating with the frequency νrf.A. Abragam, The Principles of Nuclear Magnetism, Ch. 2, Oxford Clarendon Press, 1961. The stronger the oscillating field, the faster the Rabi oscillations or the precession around the effective field in the rotating frame.
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Lousto is a professor in the RIT's School of Mathematical Sciences and co-director of the Center for Computational Relativity and Gravitation. He holds two PhDs, one in Astronomy (studying accretion disks around black holes and the structure of neutron stars) from the National University of La Plata, and one in Physics from the University of Buenos Aires (on Quantum Field Theory in curved spacetimes), received in 1987 and 1992. Carlos Lousto has an extensive research experience which ranges from observational astronomy to black hole perturbation theory and numerical relativity to string theory and quantum gravity. He has authored and co- authored over 150 papers , including several reviews and book chapters.
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The G2 uses seven calculations: # the molecular geometry is obtained by a MP2 optimization using the 6-31G(d) basis set and all electrons included in the perturbation. This geometry is used for all subsequent calculations. # The highest level of theory is a quadratic configuration interaction calculation with single and double excitations and a triples excitation contribution (QCISD(T)) with the 6-311G(d) basis set. Such a calculation in the Gaussian and Spartan programs also give the MP2 and MP4 energies which are also used. # The effect of polarization functions is assessed using an MP4 calculation with the 6-311G(2df,p) basis set.
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One goal in this context must be to protect natural life-support systems and, in particular, to prevent dangerous anthropogenic perturbation of the climate system. If the present path continues and rising energy demand is met mainly from fossil sources, this would trigger intolerable global climate change with high consequential costs, and would thus also jeopardize economic development. A second necessary goal is to eradicate energy poverty in developing countries in order that these countries can make use of development opportunities. It is essential that 2.4 billion people gain access to modern forms of energy so that they can shake off the yoke of energy poverty.
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Intermolecular forces observed between atoms and molecules can be described phenomenologically as occurring between permanent and instantaneous dipoles, as outlined above. Alternatively, one may seek a fundamental, unifying theory that is able to explain the various types of interactions such as hydrogen bonding, van der Waals forces and dipole–dipole interactions. Typically, this is done by applying the ideas of quantum mechanics to molecules, and Rayleigh–Schrödinger perturbation theory has been especially effective in this regard. When applied to existing quantum chemistry methods, such a quantum mechanical explanation of intermolecular interactions provides an array of approximate methods that can be used to analyze intermolecular interactions.
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Thinking of Feynman diagrams as a perturbation series, nonperturbative effects like tunneling do not show up, because any effect that goes to zero faster than any polynomial does not affect the Taylor series. Even bound states are absent, since at any finite order particles are only exchanged a finite number of times, and to make a bound state, the binding force must last forever. But this point of view is misleading, because the diagrams not only describe scattering, but they also are a representation of the short-distance field theory correlations. They encode not only asymptotic processes like particle scattering, they also describe the multiplication rules for fields, the operator product expansion.
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When the intermediate states at intermediate times are energy eigenstates (collections of particles with a definite momentum) the series is called old-fashioned perturbation theory. The Dyson series can be alternatively rewritten as a sum over Feynman diagrams, where at each vertex both the energy and momentum are conserved, but where the length of the energy-momentum four-vector is not necessarily equal to the mass. The Feynman diagrams are much easier to keep track of than "old- fashioned" terms, because the old-fashioned way treats the particle and antiparticle contributions as separate. Each Feynman diagram is the sum of exponentially many old-fashioned terms, because each internal line can separately represent either a particle or an antiparticle.
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An artist's rendition of a Haast's eagle attacking moa Before the arrival of human settlers, the moa's only predator was the massive Haast's eagle. New Zealand had been isolated for 80 million years and had few predators before human arrival, meaning that not only were its ecosystems extremely vulnerable to perturbation by outside species, but also the native species were ill-equipped to cope with human predators. Polynesians arrived sometime before 1300, and all moa genera were soon driven to extinction by hunting and, to a lesser extent, by habitat reduction due to forest clearance. By 1445, all moa had become extinct, along with Haast's eagle, which had relied on them for food.
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Research has found that this species of grasshopper changes its mating call in response to loud traffic noise. Lampe and Schmoll (2012) found that male grasshoppers from quiet habitats have a local frequency maximum of about 7319 Hz. In contrast, male grasshoppers exposed to loud traffic noise can create signals with a higher local frequency maximum of 7622 Hz. The higher frequencies are produced by the grasshoppers to prevent background noise from drowning out their signals. This information reveals that anthropogenic noise disturbs the acoustic signals produced by insects for communication. Similar processes of behavior perturbation, behavioral plasticity, and population level-shifts in response to noise likely occur in sound-producing marine invertebrates, but more experimental research is needed.
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More sophisticated quantum field theories, in particular those that involve a non- abelian gauge group, break the gauge symmetry within the techniques of perturbation theory by introducing additional fields (the Faddeev–Popov ghosts) and counterterms motivated by anomaly cancellation, in an approach known as BRST quantization. While these concerns are in one sense highly technical, they are also closely related to the nature of measurement, the limits on knowledge of a physical situation, and the interactions between incompletely specified experimental conditions and incompletely understood physical theory. The mathematical techniques that have been developed in order to make gauge theories tractable have found many other applications, from solid-state physics and crystallography to low-dimensional topology.
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The rate of nuclear fusion depends strongly on density. Therefore, the fusion rate in the core is in a self-correcting equilibrium: a slightly higher rate of fusion would cause the core to heat up more and expand slightly against the weight of the outer layers. This would reduce the fusion rate and correct the perturbation; and a slightly lower rate would cause the core to cool and shrink slightly, increasing the fusion rate and again reverting it to its present level. However the Sun gradually becomes hotter during its time on the main sequence, because the helium atoms in the core are denser than the hydrogen atoms they were fused from.
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Phase response curve analysis can be used to understand the intrinsic properties and oscillatory behavior of regular-spiking neurons. The neuronal PRCs can be classified as being purely positive (PRC type I) or as having negative parts (PRC type II). Importantly, the PRC type exhibited by a neuron is indicative of its input–output function (excitability) as well as synchronization behavior: networks of PRC type II neurons can synchronize their activity via mutual excitatory connections, but those of PRC type I can not. Experimental estimation of PRC in living, regular-spiking neurons involves measuring the changes in inter-spike interval in response to a small perturbation, such as a transient pulse of current.
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Most of what we know today as Pyrrhonism comes through the book Outlines of Pyrrhonism written by Sextus Empiricus over 400 years after Pyrrho's death. Most sources agree that the primary goal of Pyrrho's philosophy was the achievement of a state of ataraxia, or freedom from mental perturbation, and that he observed that ataraxia could be brought about by eschewing beliefs (dogma) about thoughts and perceptions. However, Pyrrho's own philosophy may have differed significantly in details from later Pyrrhonism. Most interpretations of the information on Pyrrho's philosophy suggest that he claimed that reality is inherently indeterminate, which, in the view of Pyrrhonism described by Sextus Empiricus, would be considered a negative dogmatic belief.
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Tayur's work covers various operations management fields, including supply chain management, lean manufacturing, and healthcare. His papers have been published in Operations Research, Management Science, Manufacturing & Service Operations Management, Mathematics of Operations Research, Mathematical Programming, Queueing Systems, IIE Transactions, and Production and Operations Management, among others. Notable collaborators include INFORMS Fellows such as Dimitris Bertsimas, Paul Glasserman, Jack Muckstadt, Georgia Perakis, and Robin Roundy (his Ph.D. thesis advisor); faculty colleagues Alan Scheller-Wolf, R. Ravi (INFORMS Fellow), and Ravindran Kannan; and Ph.D. students Srinagesh Gavirneni, Roman Kapuscinski, Pınar Keskinocak (INFORMS Fellow), and Jay Swaminathan (INFORMS Fellow). He is recognized for his operations research work in developing novel algorithms for models in stochastic inventory theory (using Infinitesimal Perturbation Analysis).
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It is important to note that many cooperative JT systems would be expected to be metals from band theory as, to produce them, a degenerate orbital has to be partially filled and the associated band would be metallic. However, under the perturbation of the symmetry-breaking distortion associated to the cooperative JTE, the degeneracies in the electronic structure are destroyed and the ground state of these systems is often found to be insulating (see e.g.). In many important cases like the parent compound for colossal magnetoresistance perovskites, LaMnO3, an increase of temperature leads to disorder in the distortions which lowers the band splitting due to the cooperative JTE, thus triggering a metal- insulator transition.
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Once it's determined if something was hit or not, the system will then give a damage output based on where the ray hit the object. Since the effect is immediate, the projectiles effectively travel at infinite speed and have a linear or otherwise simple trajectory—a practical approximation of a bullet's speed and accuracy over short distances. The hitscan method is modifiable by making some surfaces reflective, making the hitscan rays go on forever with no stop, or able to penetrate multiple objects at the same time in the same line. To improve the realism, programmers may use hitscan functions in slightly different ways; for example, applying a random perturbation to the calculated path to simulate inaccuracy.
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Cavity shape perturbation When a general shape of a resonant cavity is changed, a corresponding change in resonant frequency can be approximated as: Expression () for change in resonant frequency can additionally be written in terms of time-average stored energies as: where \Delta W_m and \Delta W_e represent time-average electric and magnetic energies contained in \Delta V. This expression can also be written in terms of energy densities as: Considerable accuracy improvements of the predictive force of Equation () can be gained by incorporating local field corrections, which simply results from the interface conditions for electromagnetic fields that are different for the displacement- field and electric-field vectors at the shape boundaries.
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The perturbation theory of toroidal invariant manifolds of dynamical systems was developed here by academician M. M. Bogolyubov, Yu. O. Mitropolsky, academician of the NAS of Ukraine and the Russian Academy of Sciences, and A. M. Samoilenko, academician of the NAS of Ukraine. The theory's methods are used to investigate oscillation processes in broad classes of applied problems, in particular, the phenomena of passing through resonance and various bifurcations and synchronizations. Sharkovsky’s order theorem was devised by its author while he worked for the Institute. It became the basis for the theory of one-dimensional dynamical systems that enabled the study of chaotic evolutions in deterministic systems, and, in particular, of ‘ideal turbulence’.
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For example, classically scale invariant field theories, where scale invariance is broken by quantum effects, provide an explanation of the flatness of inflationary potentials, as long as the theory can be studied through perturbation theory. Linde proposed a theory known as chaotic inflation in which he suggested that the conditions for inflation were actually satisfied quite generically. Inflation will occur in virtually any universe that begins in a chaotic, high energy state that has a scalar field with unbounded potential energy. However, in his model the inflaton field necessarily takes values larger than one Planck unit: for this reason, these are often called large field models and the competing new inflation models are called small field models.
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According to an alternative hypothesis, the Carnian Pluvial Event was a regional climatic perturbation mostly visible in the western Tethys and related to the uplift of a new mountain range, the Cimmerian Orogen, which resulted from the closing of a tethyan northern branch, east of the present European continent. The new mountain range was forming on the southern side of Laurasia, and acted then as the Himalayas and Asia do today for the Indian Ocean, maintaining a strong pressure gradient between the ocean and continent, and thus generating a monsoon. Summer monsoonal winds were thus intercepted by the Cimmerian mountain range and generated strong rain, thus explaining the switch to humid climate recognized in western Tethys sediments.
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In 1958, Clemence was appointed first scientific director of the U.S. Naval Observatory, a post he again addressed with enthusiasm and vigour. His own original research necessarily took a lower profile but he continued to publish on relativity, astronomical constants and time measurement, as well as collaborating on two text books.Brouwer & Clemence (1961)Woolard & Clemence (1966) However, Clemence's passion for research ultimately led him to relinquish his managerial roles in 1962, and, in 1963 Brouwer found him a post at Yale. Here, Clemence continued his work on the perturbation theory of the Earth's orbit but it was interrupted, never to be completed, in 1966 when Brouwer's death demanded that Clemence take over the administration of the department.
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The grave of Urbain Le Verrier. Le Verrier began studying the motion of Mercury as early as 1843, with a report entitled Détermination nouvelle de l ’orbite de Mercure et de ses perturbations (A New Determination of the Orbit of Mercury and its Perturbations). In 1859, Le Verrier was the first to report that the slow precession of Mercury’s orbit around the Sun could not be completely explained by Newtonian mechanics and perturbations by the known planets. He suggested, among possible explanations, that another planet (or perhaps, instead, a series of smaller 'corpuscules') might exist in an orbit even farther to the Sun than that of Mercury, to account for this perturbation.
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It is roughly 6.6 billion years old and is spinning with a projected rotational velocity of 4.4 km/s. The star has 86% of the Sun's mass and radius, and is radiating 71% of the Sun's luminosity from its photosphere at an effective temperature of 5,717 K. In 2001, a planet was discovered orbiting the star by means of the radial velocity method. This body is orbiting from the host star with a period of and a low eccentricity of 0.05. The position of this planet near the star's habitable zone means that it will have a strong gravitational perturbation effect on any potential Earth-mass planet that may be orbiting within this region.
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Employing multiple doses of siRNA powered their quantitative PCR to uncover several network features of the circadian clock, including proportional responses of gene expression, signal propagation through interacting modules, and compensation through gene expression changes. Proportional responses in downstream gene expression following siRNA-induced perturbation revealed levels of expression that were actively altered with respect to the gene being knocked down. For example, when Bmal1 was knocked down in a dose-dependent manner, Rev-ErbA alpha and Rev-ErbA beta mRNA levels were shown to decrease in a linear, proportional manner. This supported previous findings that Bmal1 directly activates Rev-erb genes and further suggests Bmal1 as a strong contributor to Rev-erb expression.
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The state variables were chosen to be the angle of attack \beta and the yaw rate r, and have omitted the speed perturbation u, together with the associated derivatives e.g. Y_u. This may appear arbitrary. However, since the timescale of the speed variation is much greater than that of the variation in angle of attack, its effects are negligible as far as the directional stability of the vehicle is concerned. Similarly, the effect of roll on yawing motion was also ignored, because missiles generally have low aspect ratio configurations and the roll inertia is much less than the yaw inertia, consequently the roll loop is expected to be much faster than the yaw response, and is ignored.
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Aces II (Advanced Concepts in Electronic Structure Theory) is an ab initio computational chemistry package for performing high-level quantum chemical ab initio calculations. Its major strength is the accurate calculation of atomic and molecular energies as well as properties using many-body techniques such as many-body perturbation theory (MBPT) and, in particular coupled cluster techniques to treat electron correlation. The development of ACES II began in early 1990 in the group of Professor Rodney J. Bartlett at the Quantum Theory Project (QTP) of the University of Florida in Gainesville. There, the need for more efficient codes had been realized and the idea of writing an entirely new program package emerged.
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Unified framework is a general formulation which yields nth \- order expressions giving mode shapes and natural frequencies for damaged elastic structures such as rods, beams, plates, and shells. The formulation is applicable to structures with any shape of damage or those having more than one area of damage. The formulation uses the geometric definition of the discontinuity at the damage location and perturbation to modes and natural frequencies of the undamaged structure to determine the mode shapes and natural frequencies of the damaged structure. The geometric discontinuity at the damage location manifests itself in terms of discontinuities in the cross- sectional properties, such as the depth of the structure, the cross-sectional area or the area moment of inertia.
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Early-Mid Jurassic (170 Ma) The Marne di Monte Serrone was first defined by Pialli in 1969.Pialli, 1969 The formation is characterised for be one of the most complete sections of the Toarcian paleobiographical strata around Europe.Palliani & Mattioli, 1994 It is also one of the best places on southern Europe where the strata shows the effects of the Lower Toarcian anoxic event (TAE). The formation also provides data about the changes after the Toarcian AE, with changes on the deposited micritic limestones and marls, what shows a local sedimentary response to the Toarcian climatic perturbation induced by the Vulcanism of the Southern Karoo-Ferrar that boiled the carbon cycle and change the mechanism of Earth climate.
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An important early success of his biophysical approach to palaeobotany was the discovery of evidence for a substantial increase in the atmospheric CO₂ concentration and 'super- greenhouse' conditions across the Triassic-Jurassic (Tr-J) boundary, 200 million years ago, based on analyses of fossil stomata and leaf morphology from Greenland. This causally linked a catastrophic extinction event with the break-up of Pangaea. Before his group's work, the Tr-J extinction represented one of the most poorly understood of the so-called 'big-five' mass extinctions in the Phanerozoic (past 540 million years). His paper resulted in major new international research programmes that subsequently identified evidence confirming the carbon cycle perturbation in marine and terrestrial sediments world-wide.
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The star is radiating 50 times the Sun's luminosity from its expanded photosphere at an effective temperature of 4,812 K. Omicron Coronae Borealis has one confirmed planet, believed to be, like HD 100655 b, one of the two least massive planets known around clump giants.Sato. Its m sin i is the least, but the true-mass depends on error and inclination. The planet was detected by measuring changes in radial velocity of the host star caused by gravitational perturbation of the orbiting object. It is orbiting with a period of 188 days, at a semimajor axis 83% of the mean separation between the Earth and the Sun, and an eccentricity of 0.19.
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873-888 osmotic,Zhou, Tian, Zou, Xie, Lei, et al. (2008) Soybean WRKY-type transcription factor genes, GmWRKY13, GmWRKY21, and GmWRKY54, confer differential tolerance to abiotic stresses in transgenic Arabidopsis plants. Plant Biotechnology Journal. 6(5). 486-503, Vanderauwera, Vandenbroucke, Inzé, Van De Cotte, Mühlenbock, et al. (2012) AtWRKY15 perturbation abolishes the mitochondrial stress response that steers osmotic stress tolerance in Arabidopsis. Proceedings of the National Academy of Sciences. 109(49). 20113-20118, Li, Besseau, Törönen, Sipari, Kollist, et al. (2013) Defense-related transcription factors WRKY70 and WRKY54 modulate osmotic stress tolerance by regulating stomatal aperture in Arabidopsis. New Phytologist. 200(2). 457-472 oxidative,Liu, Hong, Zhang, Li, Huang, et al.
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Other scientists specializing in General Relativity require the energy to be small enough for curvature of space to agree with observed astronomy. The Heisenberg uncertainty principle allows the energy to be as large as needed to promote quantum actions for a brief moment of time, even if the average energy is small enough to satisfy relativity and flat space. To cope with disagreements, the vacuum energy is described as a virtual energy potential of positive and negative energy. In quantum perturbation theory, it is sometimes said that the contribution of one-loop and multi-loop Feynman diagrams to elementary particle propagators are the contribution of vacuum fluctuations, or the zero- point energy to the particle masses.
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When a new perturbation of temperature of this type happens, temperatures within the system change in time toward a new equilibrium with the new conditions, provided that these do not change. After equilibrium, heat flow into the system once again equals the heat flow out, and temperatures at each point inside the system no longer change. Once this happens, transient conduction is ended, although steady-state conduction may continue if heat flow continues. If changes in external temperatures or internal heat generation changes are too rapid for the equilibrium of temperatures in space to take place, then the system never reaches a state of unchanging temperature distribution in time, and the system remains in a transient state.
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Intermediate stage of a jet breaking into drops. Radii of curvature in the axial direction are shown. Equation for the radius of the stream is R(z) = R_0 + A_k \cos(kz), where R_0 is the radius of the unperturbed stream, A_k is the amplitude of the perturbation, \scriptstyle z is distance along the axis of the stream, and k is the wave number The explanation of this instability begins with the existence of tiny perturbations in the stream. These are always present, no matter how smooth the stream is (for example, in the liquid jet nozzle, there is vibration on the liquid stream due to a friction between the nozzle and the liquid stream).
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Segundo realizes the discussion so far has led to dangerous issues. If his analysis is the logical conclusion of the Medellín Conference, there are serious implications for the Church. He notes two facts; # “the alarm of Latin American church authorities at the unexpected consequences of the doctrines they formulate at Medellín as an accurate reflection of Vatican II # The perturbation of significant groups of Christian lay people with a magisterium that seems to be in steady retreat ever since Medellin.” To deal with these problems, Segundo first needs to deal with the relationship of faith and ideology. He begins with a theme from Albert Camus’ Caligula, that life is only lived once, in a forward direction.
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Shifts in phase (or behavior of neurons) caused due to a perturbation (an external stimulus) can be quantified within a Phase Response Curve (PRC) to predict synchrony in coupled and oscillating neurons. These effects can be computed, in the case of advances or delays to responses, to observe the changes in the oscillatory behavior of neurons, pending on when a stimulus was applied in the phase cycle of an oscillating neuron. The key to understanding this is in the behavioral patterns of neurons and the routes neural information travels. Neural circuits are able to communicate efficiently and effectively within milliseconds of experiencing a stimulus and lead to the spread of information throughout the neural network.
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Arguments that claim the activity pattern observed in neurons is not phase resetting, but could instead be the response to evoked potentials (ERPs), include: #If the ERP was generated due to phase resetting, measuring the phase concentration alone is not enough to prove that phase resetting is occurring. An example of this is measuring while filtering data as this may actually induce an artificial oscillation in response to perturbation. It has been suggested that this argument may be overcome if there is no increase in power of the phase reset from pre-stimulus to post-stimulus. #The amplitude and phase of ongoing oscillations at the time a stimulus is applied should influence the ERP once generated by current oscillations.
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In mathematical physics, noncommutative quantum field theory (or quantum field theory on noncommutative spacetime) is an application of noncommutative mathematics to the spacetime of quantum field theory that is an outgrowth of noncommutative geometry and index theory in which the coordinate functions It is possible to have a noncommuting time coordinate as in the paper by Doplicher, Fredenhagen and Roberts mentioned below, but this causes many problems such as the violation of unitarity of the S-matrix. Hence most research is restricted to so-called "space-space" noncommutativity. There have been attempts to avoid these problems by redefining the perturbation theory. However, string theory derivations of noncommutative coordinates excludes time-space noncommutativity.
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The transient climate response (TCR) is defined as "is the change in the global mean surface temperature, averaged over a 20-year period, centered at the time of atmospheric carbon dioxide doubling, in a climate model simulation" in which the atmospheric concentration is increasing at 1% per year. This estimate is generated using shorter-term simulations. The transient response is lower than the equilibrium climate sensitivity, because slower feedbacks, which exacerbate the temperature increase, take more time to respond in full to an increase in the atmospheric concentration. For instance, the deep ocean takes many centuries to reach a new steady state after a perturbation; during this time, it continues to serve as heatsink, cooling the upper ocean.
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Attempts to overcome this fundamental limitation using low frequency coils and superconducting magnetic field sensors have not led to widespread applications. A recent technique, referred to as Lorentz force eddy current testing (LET),Uhlig, R. P., Zec, M., Brauer, H. and Thess, A. 2012 "Lorentz Force Eddy Current Testing:a Prototype Model". Journal of Nondestructive Evaluation, 31, 357–372 exploits the advantages of applying DC magnetic fields and relative motion providing deep and relatively fast testing of electrically conducting materials. In principle, LET represents a modification of the traditional eddy current testing from which it differs in two aspects, namely (i) how eddy currents are induced and (ii) how their perturbation is detected.
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In Electronic Health Records (EHR’s) data masking, or controlled access, is the process of concealing patient health data from certain healthcare providers. Patients have the right to request the masking of their personal information, making it inaccessible to any physician, or a particular physician, unless a specific reason is provided. Data masking is also performed by healthcare agencies to restrict the amount of information that can be accessed by external bodies such as researchers, health insurance agencies and unauthorised individuals. It is a method used to protect patients’ sensitive information so that privacy and confidentiality are less of a concern. Techniques used to alter information within a patient’s EHR include data encryption, obfuscation, hashing, exclusion and perturbation.
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In mitosis, unlike dynactin or dynein perturbation that causes mitotic spindle disarrangement and mitotic arrest, dynactin p27/p25 depletion does not affect mitotic spindle formation, pole focusing or dynein/dynactin targeting to kinetochores. However, dynactin p27/p25 are required for normal chromosome alignment, kinetochore-microtubule interaction, and proper timing of anaphase onset. Dynactin p27 C-terminal T186 residue is phosphorylated by cyclin- dependent kinase 1 (Cdk1) in mitosis and helps target polo-like kinase 1 (Plk1) to kinetochores during prometaphase. This activity facilitates phosphorylation of important downstream kinetochore targets (such as tension- sensing 3F3/2 phospho-epitope) of Plk1, which is important for recruitment of spindle assembly checkpoint proteins such as Mad1 and proper kinetochore- microtubule attachment.
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They found evidence of a planet orbiting the star with a period of about seven years. Although there is a high level of noise in the radial velocity data due to magnetic activity in its photosphere, any periodicity caused by this magnetic activity is expected to show a strong correlation with variations in emission lines of ionized calcium (the Ca II H and K lines). Because no such correlation was found, a planetary companion was deemed the most likely cause. This discovery was supported by astrometric measurements of Epsilon Eridani made between 2001 and 2003 with the Hubble Space Telescope, which showed evidence for gravitational perturbation of Epsilon Eridani by a planet.
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Screening of negatively charged particle in a pool of positive ions Friedel oscillations , named after French physicist Jacques Friedel, arise from localized perturbations in a metallic or semiconductor system caused by a defect in the Fermi gas or Fermi liquid. Friedel oscillations are a quantum mechanical analog to electric charge screening of charged species in a pool of ions. Whereas electrical charge screening utilizes a point entity treatment to describe the make-up of the ion pool, Friedel oscillations describing fermions in a Fermi fluid or Fermi gas require a quasi-particle or a scattering treatment. Such oscillations depict a characteristic exponential decay in the fermionic density near the perturbation followed by an ongoing sinusoidal decay resembling sinc function.
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Although lipidomics is under the umbrella of the more general field of "metabolomics", lipidomics is itself a distinct discipline due to the uniqueness and functional specificity of lipids relative to other metabolites. In lipidomic research, a vast amount of information quantitatively describing the spatial and temporal alterations in the content and composition of different lipid molecular species is accrued after perturbation of a cell through changes in its physiological or pathological state. Information obtained from these studies facilitates mechanistic insights into changes in cellular function. Therefore, lipidomic studies play an essential role in defining the biochemical mechanisms of lipid-related disease processes through identifying alterations in cellular lipid metabolism, trafficking and homeostasis.
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String field theory (SFT) is a formalism in string theory in which the dynamics of relativistic strings is reformulated in the language of quantum field theory. This is accomplished at the level of perturbation theory by finding a collection of vertices for joining and splitting strings, as well as string propagators, that give a Feynman diagram-like expansion for string scattering amplitudes. In most string field theories, this expansion is encoded by a classical action found by second-quantizing the free string and adding interaction terms. As is usually the case in second quantization, a classical field configuration of the second-quantized theory is given by a wave function in the original theory.
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Let's say we fashioned a loop-de-loop around the base of the mountain so that the ball will shoot up it and return to the lake (no rolling friction or air resistance). Now we have a system that stays in its rest state (the ball in the lake) until a perturbation knocks it out (rolling down the hill) but eventually returns to its rest state (back in the lake). In this example, gravity is the driving force and spatial dimensions x (horizontal) and y (vertical) are the variables. In the Morris Lecar neuron, the fundamental force is electromagnetic and V and N are the new phase space, but the dynamical picture is essentially the same.
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Three transcription factors, OCT4, SOX2, and NANOG – the first two of which are used in induced pluripotent stem cell (iPSC) reprogramming, along with Klf4 and c-Myc – are highly expressed in undifferentiated embryonic stem cells and are necessary for the maintenance of their pluripotency. It is thought that they achieve this through alterations in chromatin structure, such as histone modification and DNA methylation, to restrict or permit the transcription of target genes. While highly expressed, their levels require a precise balance to maintain pluripotency, perturbation of which will promote differentiation towards different lineages based on how the gene expression levels change. Differential regulation of Oct-4 and SOX2 levels have been shown to precede germ layer fate selection.
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In contrast, perturbation of glycan processing (enzymatic removal/addition of carbohydrate residues to the glycan), which occurs in both the endoplasmic reticulum and Golgi apparatus, is dispensable for isolated cells (as evidence by survival with glycosides inhibitors) but can lead to human disease (congenital disorders of glycosylation) and can be lethal in animal models. It is therefore likely that the fine processing of glycans is important for endogenous functionality, such as cell trafficking, but that this is likely to have been secondary to its role in host-pathogen interactions. A famous example of this latter effect is the ABO blood group system. Glycosylation is also known to occur on nucleocytoplasmic proteins in the form of O-GlcNAc.
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The seeker must first understand that Allah is al-Razzaq (the Provider), and submit and be content with the will of Allah . #al-ghamm – depression: passion (hawā) conduces to anguish (ghamm) whenever reason is allowed to represent itself as grievous or painful the loss of the suitable or desirable and is, therefore, a "rational affection" that can cause the soul untold suffering and perturbation. #al-manhiyat – Eight Hundred Forbidden Acts #ghaflah – neglect and forgetfulness of God, indifference: those guilty of ghaflah, the ghāfilün, are those who "know only a surface appearance of the life of this world, and are heedless of the hereafter" (30:7). #kibr – arrogance or regarding one's self to be superior to others.
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The high affinity IgE receptor plays a central role in allergic disease, coupling allergen and mast cell to initiate the inflammatory and immediate hypersensitivity responses that are characteristic of disorders such as hay fever and asthma. The allergic response occurs when 2 or more IgE receptors are crosslinked via IgE molecules that in turn are bound to an allergen (antigen) molecule. A perturbation occurs that brings about the release of histamine and proteases from the granules in the cytoplasm of the mast cell and leads to the synthesis of prostaglandins and leukotrienes—potent effectors of the hypersensitivity response. The IgE receptor consists of 3 subunits: alpha (this protein), beta, and gamma; only the alpha subunit is glycosylated.
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There is also exchange with carbon in the sediments, e.g., burial of organic carbon, which is important for carbon sequestration in aquatic habitats.Regnier, P., Friedlingstein, P., Ciais, P., Mackenzie, F. T., Gruber, N., Janssens, I. A., et al. (2013). Anthropogenic perturbation of the carbon fluxes from land to ocean. Nat. Geosci. 6, 597–607. doi: 10.1038/ngeo1830 Aquatic systems are very important in global carbon sequestration; e.g., when different European ecosystems are compared, inland aquatic systems form the second largest carbon sink (19–41 Tg C y-1); only forests take up more carbon (125–223 Tg C y-1).Luyssaert, S., Abril, G., Andres, R., Bastviken, D., Bellassen, V., Bergamaschi, P., et al. (2012).
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Later Migulin suggested that the phenomenon occurred "due to a rare concourse of various circumstances, that is the launch of the satellite Kosmos-955, the strong magnetic perturbation due to solar flare and our scientific experiment of influencing the ionosphere with low frequency radio waves". In the interview, published in 1977 by Kansan Uutiset and Uusi Suomi, the employee of Nurmijärvi geophysical observatory Matti Kivinen assumed that an unidentified object over Finland could be the remnant of a launch vehicle or satellite. James Oberg attributed the Petrozavodsk object to the launch of the Soviet satellite Kosmos-955 from Plesetsk Cosmodrome, which took place on September 20 at about 3:58 local time.
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Lovelock and Watson demonstrated the stability of Daisyworld by making its sun evolve along the main sequence, taking it from low to high solar constant. This perturbation of Daisyworld's receipt of solar radiation caused the balance of daisies to gradually shift from black to white but the planetary temperature was always regulated back to this optimum (except at the extreme ends of solar evolution). This situation is very different from the corresponding abiotic world, where temperature is unregulated and rises linearly with solar output. Later versions of Daisyworld introduced a range of grey daisies, as well as populations of grazers and predators, and found that these further increased the stability of the homeostasis.
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With increasing knowledge of classical solitons, possible technical applicability came into perspective, with the most promising one at present being the transmission of optical solitons via glass fibers for the purpose of data transmission. In contrast to conservative systems, solitons in fibers dissipate energy and this cannot be neglected on an intermediate and long time scale. Nevertheless, the concept of a classical soliton can still be used in the sense that on a short time scale dissipation of energy can be neglected. On an intermediate time scale one has to take small energy losses into account as a perturbation, and on a long scale the amplitude of the soliton will decay and finally vanish.
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His work during this period, which used equations of rotation to express various spinning speeds, ultimately proved important to his Nobel Prize–winning work, yet because he felt burned out and had turned his attention to less immediately practical problems, he was surprised by the offers of professorships from other renowned universities, including the Institute for Advanced Study, the University of California, Los Angeles, and the University of California, Berkeley. Feynman diagram of electron/positron annihilation Feynman was not the only frustrated theoretical physicist in the early post-war years. Quantum electrodynamics suffered from infinite integrals in perturbation theory. These were clear mathematical flaws in the theory, which Feynman and Wheeler had unsuccessfully attempted to work around.
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Kepler-56b is about 0.1028 AU away from its host star (about one-tenth of the distance between Earth to the Sun), making it even closer to its parent star than Mercury and Venus. It takes 10.5 days for Kepler-56b to complete a full orbit around Kepler-56. Further research shows that Kepler-56b's orbit is about 45° misaligned to the host star's equator. Later radial velocity measurements have revealed evidence of a gravitational perturbation but currently it is not clear if it is a nearby star or a third planet (a possible Kepler-56d). Both Kepler-56b and Kepler-56c will be devoured by their parent star in about 130 and 155 million years.
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Asymptotic freedom can be derived by calculating the beta-function describing the variation of the theory's coupling constant under the renormalization group. For sufficiently short distances or large exchanges of momentum (which probe short-distance behavior, roughly because of the inverse relationship between a quantum's momentum and De Broglie wavelength), an asymptotically free theory is amenable to perturbation theory calculations using Feynman diagrams. Such situations are therefore more theoretically tractable than the long-distance, strong-coupling behavior also often present in such theories, which is thought to produce confinement. Calculating the beta-function is a matter of evaluating Feynman diagrams contributing to the interaction of a quark emitting or absorbing a gluon.
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In modern physics, the electromagnetic field is understood to be not a classical field, but rather a quantum field; it is represented not as a vector of three numbers at each point, but as a vector of three quantum operators at each point. The most accurate modern description of the electromagnetic interaction (and much else) is quantum electrodynamics (QED), For a good qualitative introduction see: which is incorporated into a more complete theory known as the Standard Model of particle physics. In QED, the magnitude of the electromagnetic interactions between charged particles (and their antiparticles) is computed using perturbation theory. These rather complex formulas produce a remarkable pictorial representation as Feynman diagrams in which virtual photons are exchanged.
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He interpreted the Virasoro algebra discovered in consistency conditions as a geometrical symmetry of a world- sheet conformal field theory, formulating string theory in terms of two dimensional quantum field theory. He used the conformal invariance to calculate tree level string amplitudes on many worldsheet domains. Mandelstam was the first to explicitly construct the fermion scattering amplitudes in the Ramond and Neveu–Schwarz sectors of superstring theory, and later gave arguments for the finiteness of string perturbation theory. In quantum field theory, Mandelstam and independently Sidney Coleman extended work of Tony Skyrme to show that the two dimensional quantum Sine-Gordon model is equivalently described by a Thirring model whose fermions are the kinks.
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In quantum mechanics, dynamical pictures (or representations) are the multiple equivalent ways to mathematically formulate the dynamics of a quantum system. The two most important ones are the Heisenberg picture and the Schrödinger picture. These differ only by a basis change with respect to time-dependency, analogous to the Lagrangian and Eulerian specification of the flow field: in short, time dependence is attached to quantum states in the Schrödinger picture and to operators in the Heisenberg picture. There is also an intermediate formulation known as the interaction picture (or Dirac picture) which is useful for doing computations when a complicated Hamiltonian has a natural decomposition into a simple "free" Hamiltonian and a perturbation.
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Whether arm swing is a passive, natural motion caused by the rotation of torso or is an active motion that requires active muscle work has been a critical discussion on arm swing that could illuminate its benefit and function. A recent study concentrated on the energy consumption during walking showed that at low speeds arm swing is a passive motion dictated by the kinematics of torso, no different from a pair of pendula hung from the shoulders. Active upper extremity muscle work, controlled by the brain, only takes part when there is a perturbation and restores that natural motion. However, at higher speeds, the passive motion is insufficient to explain the amplitude of the swing observed in the experiments.
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It embraces the power of nonlinear feedback and puts it to full use. It is a robust control method that is based on extension of the system model with an additional and fictitious state variable, representing everything that the user does not include in the mathematical description of the plant. This virtual state (sum of internal and external disturbances, usually denoted as a "total disturbance") is estimated online with a state observer and used in the control signal in order to decouple the system from the actual perturbation acting on the plant. This disturbance rejection feature allows user to treat the considered system with a simpler model, since the negative effects of modeling uncertainty are compensated in real time.
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Rydberg atoms form commonly in plasmas due to the recombination of electrons and positive ions; low energy recombination results in fairly stable Rydberg atoms, while recombination of electrons and positive ions with high kinetic energy often form autoionising Rydberg states. Rydberg atoms’ large sizes and susceptibility to perturbation and ionisation by electric and magnetic fields, are an important factor determining the properties of plasmas. Condensation of Rydberg atoms forms Rydberg matter, most often observed in form of long-lived clusters. The de-excitation is significantly impeded in Rydberg matter by exchange-correlation effects in the non-uniform electron liquid formed on condensation by the collective valence electrons, which causes extended lifetime of clusters.
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