The same basic phenomenon, called double-diffusive convection, creates layers of water in the ocean.
|
|
Instead, we get extended sensory descriptions of life on Lefkáda, memories that glow through a diffusive haze of metaphor.
|
|
" His main reservation was slavery and how it made "the right of suffrage" more "diffusive in the Northern than the Southern States.
|
|
But the effect of her being on those around her was incalculably diffusive: for the growing good of the world is partly dependent on unhistoric acts; and that things are not so ill with you and me as they might have been is half owing to the number who lived faithfully a hidden life, and rest in unvisited tombs.
|
|
Double diffusive convection holds importance in natural processes and engineering applications. The effect of double diffusive convection is not limited to oceanography, also occurring in geology, astrophysics, and metallurgy.
|
|
Nonetheless, some diffusive upwelling does probably occur. Location of the Southern Ocean gyres.
|
|
Strangely however, termites that carry a highly oxygen-sensitive symbiotic bacteria demonstrate continuous, diffusive ventilation.
|
|
Among the rare causes of diffusive peritonitis is perforation of the intestine by lumbricoid worms.
|
|
On long timescales, diffusive creep in hillslope soils leads to a characteristic rounding of ridges in the landscape.Roering, Joshua J., James W. Kirchner, and William E. Dietrich. "Evidence for nonlinear, diffusive sediment transport on hillslopes and implications for landscape morphology." Water Resources Research 35.3 (1999): 853–70.
|
|
Diffusive bonding occurs when species from one surface penetrate into an adjacent surface while still being bound to the phase of their surface of origin. One instructive example is that of polymer- on-polymer surfaces. Diffusive bonding in polymer-on-polymer surfaces is the result of sections of polymer chains from one surface interdigitating with those of an adjacent surface. The freedom of movement of the polymers has a strong effect on their ability to interdigitate, and hence, on diffusive bonding.
|
|
However, it can also happen due to internal diffusion of heat (the warmer layer slowly heats the adjacent cooler one) or other physical properties. This often causes mixing at the interface, creating new diffusive layers (see photo of coffee and milk). Sometimes, two physical properties diffuse between layers simultaneously; salt and temperature, for instance. This may form diffusive layers or even salt fingering, when the surfaces of the diffusive layers become so wavy that there are "fingers" of layers reaching up and down.
|
|
Because of its diffusive interaction with seawater, the lower part of the sea ice matrix is typically characterized by higher nutrient concentrations.
|
|
The required diffusion coefficients, however, appear to be larger than are observed in the real ocean. Nonetheless, some diffusive upwelling does probably occur.
|
|
The algebraic stress model arises in computational fluid dynamics. Two main approaches can be undertaken. In the first, the transport of the turbulent stresses is assumed proportional to the turbulent kinetic energy; while in the second, convective and diffusive effects are assumed to be negligible. Algebraic stress models can only be used where convective and diffusive fluxes are negligible, i.e.
|
|
Photoacoustic imaging is a recently developed hybrid biomedical imaging modality based on the photoacoustic effect. It combines the advantages of optical absorption contrast with an ultrasonic spatial resolution for deep imaging in (optical) diffusive or quasi-diffusive regime. Recent studies have shown that photoacoustic imaging can be used in vivo for tumor angiogenesis monitoring, blood oxygenation mapping, functional brain imaging, and skin melanoma detection, etc.
|
|
During deformation, minerals can migrate by plastic flow or may grow by diffusive mass transport into the lower-stress regions created by a rigid porphyroclast or porphyroblast.
|
|
Schmittmann is the coauthor with Royce King-Ping Zia of the book Statistical Mechanics of Driven Diffusive Systems (Phase Transitions and Critical Phenomena, vol. 17, Academic Press, 1995).
|
|
He has edited several books. These include Environmental Fluid Dynamics Handbook (Taylor & Francis, 2013), Human Health and National Security Implications of Climate Change (Springer, 2012), and Double Diffusive Convection (AGU, 1994).
|
|
In the order of increasing simplifications, by removing some terms of the full 1D Saint-Venant equations (aka Dynamic wave equation), we get the also classical Diffusive wave equation and Kinematic wave equation.
|
|
In atmospheric radiation, Chandrasekhar's X- and Y-function appears as the solutions of problems involving diffusive reflection and transmission, introduced by the Indian American astrophysicist Subrahmanyan Chandrasekhar.Chandrasekhar, Subrahmanyan. Radiative transfer. Courier Corporation, 2013.
|
|
Gas exchange patterns in insects can range from continuous and diffusive ventilation, to discontinuous gas exchange. During continuous gas exchange, oxygen is taken in and carbon dioxide is released in a continuous cycle. In discontinuous gas exchange, however, the insect takes in oxygen while it is active and small amounts of carbon dioxide are released when the insect is at rest. Diffusive ventilation is simply a form of continuous gas exchange that occurs by diffusion rather than physically taking in the oxygen.
|
|
Single-walled carbon nanotubes have the ability to conduct electricity. This conduction can be ballistic, diffusive, or based on scattering. When ballistic in nature conductance can be treated as if the electrons experience no scattering.
|
|
Combustion science and technology, 62(4-6), 297-309.Dold, J., Daou, J., & Weber, R. (2004). Reactive- diffusive stability of premixed flames with modified Zeldovich-Linán kinetics. Simplicity, Rigor and Relevance in Fluid Mechanics, 47-60.
|
|
Physical Review E 61: 4156 – 4160. However, a diffusive model of vascular development would seem to fall short of the complexity of capillary beds and the interwoven network of arteries and veins.Nguyen, T-H., et al.
|
|
Unfortunately the gearing arrangements (and thus the key) were fixed for any given machine, so triple encryption was recommended for security: a secret nonlinear step, followed by the wide diffusive step from the machine, followed by a third secret nonlinear step. (The much later Even-Mansour cipher also uses an unkeyed diffusive middle step). Such a combination was actually very powerful for 1929, and indicates that Hill apparently understood the concepts of a meet-in-the-middle attack as well as confusion and diffusion. Unfortunately, his machine did not sell.
|
|
Beate Schmittmann is a German condensed matter physicist and academic administrator who works at Iowa State University as dean of the Iowa State University College of Liberal Arts & Sciences. Her research includes work on driven diffusive systems, biomolecular transport, and epidemiology.
|
|
An effect that affects both of these variables is the input of cold freshwater from an iceberg. Double diffusive convection is important in understanding the evolution of a number of systems that have multiple causes for density variations. These include convection in the Earth's oceans (as mentioned above), in magma chambers, and in the sun (where heat and helium diffuse at differing rates). Sediment can also be thought as having a slow Brownian diffusion rate compared to salt or heat, so double diffusive convection is thought to be important below sediment laden rivers in lakes and the ocean.
|
|
On the contrary, relaxation of the phason strain is diffusive and is much slower. Therefore, metastable quasicrystals grown by rapid quenching from the melt exhibit built-in phason strain associated with shifts and anisotropic broadenings of X-ray and electron diffraction peaks.
|
|
This further corroborates the finding that in nutrient-starved bacteria, the cytoplasm transitions into a glasslike substance. Thus, ATP-hydrolysis by motor proteins appear to be critical to sustain cytoplasmic fluidity, which is crucial to vesicle transport and diffusive motion in the cytoskeleton.
|
|
Materials Science Laboratory - Columnar-to- Equiaxed Transition in Solidification Processing (CETSOL) and Microstructure Formation in Casting of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions (MICAST) are two investigations which will examine different growth patterns and evolution of microstructures during crystallization of metallic alloys in microgravity. MICAST studies microstructure formation during casting of technical alloys under diffusive and magnetically controlled convective conditions. The experimental results together with parametric studies using numerical simulations, will be used to optimize industrial casting processes. MICAST identifies and controls experimentally the fluid-flow patterns that affect microstructure evolution during casting processes, and to develop analytical and advanced numerical models.
|
|
Diffusive gradients in thin films (DGT) samplers passively sample ionic trace metals, as well as antibiotics, oxyanions, bisphenols, and nanoparticles in different configurations. They are composed of plastic pistons and caps, with a window that exposes a binding gel, diffusive gel, and filter membrane to the sampling water. They can be used in both freshwater and marine environments, as well as in the water located between freshwater and marine sediment particles, called pore water or interstitial water. Once the mass of accumulated contaminants on the DGT sampler is known, the DGT equation (based on Fick's law) can be used to calculate the time averaged water concentration of contaminants.
|
|
In these circumstances, if perchance it happens that no transfer of matter is actualized, and there are no cross-effects, then the thermodynamic concept and the mechanical concept coincide, as if one were dealing with closed systems. But when there is transfer of matter, the exact laws by which temperature gradient drives diffusive flux of internal energy, rather than being exactly knowable, mostly need to be assumed, and in many cases are practically unverifiable. Consequently, when there is transfer of matter, the calculation of the pure 'heat flux' component of the diffusive flux of internal energy rests on practically unverifiable assumptions.Denbigh, K.G. (1951), p. 56.
|
|
FSM was developed by Ming Guo and David A. Weitz to probe stochastic intracellular forces generated by motor proteins. Far from a liquid void, the cytoplasm contains a complex meshwork of actin and myosin conferring structural support to the cell, as well as harbouring vesicles and mitochondria among other organelles. Recent research on the macromolecular crowding inside the cytoplasm raises concerns whether diffusive-like motion of large molecules have been mistakenly attributed to Brownian forces. Instead, there are suspicions that myosin motor proteins, which tug randomly on the actin filaments embedded with large molecules, give rise to diffusive-like motion of molecules inside cells.
|
|
Baines’ main research focus is Geophysical Fluid Dynamics along with Climate Dynamics, incorporating Oceanography, Topographic Effects in Stratified Flows and Volcano Dynamics. His doctoral thesis included work on forced wave motion in rotating and stratified fluids, and a fundamental study of the nature of double-diffusive convection.
|
|
The Thouless energy is a characteristic energy scale of diffusive disordered conductors. It was first introduced by the Scottish-American physicist David J. Thouless when studying Anderson localization,J. T. Edwards and D. J. Thouless, "Numerical studies of localization in disordered systems," J. Phys. C: Solid State Phys.
|
|
The different approaches towards SPL can be classified by their goal to either add or remove material, by the general nature of the process either chemical or physical, or according to the driving mechanisms of the probe-surface interaction used in the patterning process: mechanical, thermal, diffusive and electrical.
|
|
De Groot, S.R., Mazur, P. (1962), p. 30. If cross-effects that result in diffusive transfer of internal energy were also labeled as heat transfers, they would sometimes violate the rule that pure heat transfer occurs only down a temperature gradient, never up one. They would also contradict the principle that all heat transfer is of one and the same kind, a principle founded on the idea of heat conduction between closed systems. One might to try to think narrowly of heat flux driven purely by temperature gradient as a conceptual component of diffusive internal energy flux, in the thermodynamic view, the concept resting specifically on careful calculations based on detailed knowledge of the processes and being indirectly assessed.
|
|
This version contains an actual ending; however, the text still has many flaws and it is debatable whether it can be considered finished.William M. Gibson: "All these developments take place in something like a dramatic vacuum" ... "Still 'diffusive' and disjointed." Mark Twain. The Mysterious Stranger Manuscripts (Kindle Locations 143-147).
|
|
If added to a lake without significant bulk water flow, the ink would simply disperse outwards from its source in a diffusive manner, which is not advection. Note that as it moves downstream, the "pulse" of ink will also spread via diffusion. The sum of these processes is called convection.
|
|
CTRW was introduced by Montroll and Weiss as a generalization of physical diffusion process to effectively describe anomalous diffusion, i.e., the super- and sub-diffusive cases. An equivalent formulation of the CTRW is given by generalized master equations. A connection between CTRWs and diffusion equations with fractional time derivatives has been established.
|
|
Numerical diffusion is a difficulty with computer simulations of continua (such as fluids) wherein the simulated medium exhibits a higher diffusivity than the true medium. This phenomenon can be particularly egregious when the system should not be diffusive at all, for example an ideal fluid acquiring some spurious viscosity in a numerical model.
|
|
Matter and internal energy cannot permeate or penetrate such a wall. For an open system, there is a wall that allows penetration by matter. In general, matter in diffusive motion carries with it some internal energy, and some microscopic potential energy changes accompany the motion. An open system is not adiabatically enclosed.
|
|
In addition to displacive transformation and diffusive transformation, a new type of phase transformation that involves a displasive sublattice transition and atomic diffusion was discovered using a high- pressure x-ray diffraction system. The new transformation mechanism has been christened a pseudomartensitic transformation.Kristin Leutwyler New phase transition Scientific American, May 2, 2001.
|
|
The HLLC (Harten-Lax-van Leer-Contact) solver was introduced by Toro. It restores the missing Rarefaction wave by some estimates, like linearisations, these can be simple but also more advanced exists like using the Roe average velocity for the middle wave speed. They are quite robust and efficient but somewhat more diffusive.
|
|
It follows that there is no well-founded definition of quantities of energy transferred as heat or as work associated with transfer of matter. Nevertheless, for the thermodynamical description of non-equilibrium processes, it is desired to consider the effect of a temperature gradient established by the surroundings across the system of interest when there is no physical barrier or wall between system and surroundings, that is to say, when they are open with respect to one another. The impossibility of a mechanical definition in terms of work for this circumstance does not alter the physical fact that a temperature gradient causes a diffusive flux of internal energy, a process that, in the thermodynamic view, might be proposed as a candidate concept for transfer of energy as heat. In this circumstance, it may be expected that there may also be active other drivers of diffusive flux of internal energy, such as gradient of chemical potential which drives transfer of matter, and gradient of electric potential which drives electric current and iontophoresis; such effects usually interact with diffusive flux of internal energy driven by temperature gradient, and such interactions are known as cross-effects.
|
|
Tannehill, J. C., Anderson, D. A., and Pletcher, R. H., Computational Fluid Dynamics and Heat Transfer, 2nd ed., Taylor & Francis (1997). Unlike first-order upwind scheme, the MacCormack does not introduce diffusive errors in the solution. However, it is known to introduce dispersive errors (Gibbs phenomenon) in the region where the gradient is high.
|
|
In probability theory, the Brownian web is an uncountable collection of one- dimensional coalescing Brownian motions, starting from every point in space and time. It arises as the diffusive space-time scaling limit of a collection of coalescing random walks, with one walk starting from each point of the integer lattice Z at each time.
|
|
These waves are known as a paramagnon, and undergo diffusive (instead of ballistic or long range) transport. The concept was first proposed based on the spin fluctuations in transition metals, by Berk and Schrieffer and Doniach and Engelsberg, to explain additional repulsion between electrons in some metals, which reduces the critical temperature for superconductivity.
|
|
They probably trace shock fronts in which particles are accelerated via the diffusive shock acceleration mechanism. Among them are double-relics with the two relics located on both sides of a cluster center. Their integrated radio spectrum usually follows a single power-law. Radio phoenices are related to radio-loud active galactic nuclei (AGN).
|
|
The GSSHA model was developed from the outset to be capable of 'long term' simulations consisting of multiple events. As such, required inputs include meteorological variables, and surface energy- balance parameters. Seasonality in evapotranspiration parameters is included in the model. Overland and channel flow hydraulics are based on explicit, finite-volume, diffusive wave schemes.
|
|
The evolution of vesiculation can be summarized in these steps: # The magma becomes progressively saturated with volatiles when water and carbon dioxide dissolves in it. Nucleation of bubbles start when then magma is supersaturated with these volatiles. # Bubbles continue to grow by diffusive transfer of water gases from the magma. Stresses buildup inside the volcanic dome.
|
|
A second biased Monte Carlo simulation is virtual move Monte Carlo. This is a cluster move algorithm. It was made to improve relaxation times in strongly interacting, low density systems and to better approximate diffusive dynamics in the system. This simulation is good for self-assembling and polymeric systems that can find natural moves that relax the system.
|
|
If the main objective is to control temperature, care should be exercised to use a small damping constant \gamma. As \gamma grows, it spans from the inertial all the way to the diffusive (Brownian) regime. The Langevin dynamics limit of non-inertia is commonly described as Brownian dynamics. Brownian dynamics can be considered as overdamped Langevin dynamics, i.e.
|
|
Double diffusive convection occurs when convection of the fluid is driven by both thermal and concentration gradients, and the temperature and concentration diffusivities take different values. The bifurcation is found in an orbit that is born in a global saddle-loop bifurcation, becomes chaotic in a period doubling cascade, and disappears in the blue sky catastrophe.
|
|
It has thus been suggested that learning (of task irrelevant stimuli) is contingent upon spatially diffusive learning signals. Similar effects, but upon a shorter time scale, have been found for memory processes and in some cases is called attentional boosting. Thus, when an important (alerting) event occurs, learning may also affect concurrent, non- attended and non-salient stimuli.
|
|
The duration of the vesiculation event can be controlled by the decrease of water content across a distance in the sample as the volatiles escape into the bubbles. The more gradual change of the water content curve represents a longer vesiculation event. Therefore, the explosive potential of volcanic dome can be estimated from the water content profile derived from the diffusive model.
|
|
Areas of upwelling in red The major upwellings in the ocean are associated with the divergence of currents that bring deeper, colder, nutrient rich waters to the surface. There are at least five types of upwelling: coastal upwelling, large-scale wind- driven upwelling in the ocean interior, upwelling associated with eddies, topographically-associated upwelling, and broad-diffusive upwelling in the ocean interior.
|
|
The graph of eruption rate shows plunges which indicate lessening in diffusive activity or cooling of old flow surface. As well, it shows a spike, which indicates the beginning of a new eruption. The power output flux graph compares Zamama with other Ionian volcanoes of the same eruptive style. Galileo NIMS instrument collected data on volcanic emissions to analyze the power output.
|
|
McInnes graduated in 1988 from Muhlenberg College, with a double major in mathematics and physics. She completed her doctorate in applied mathematics in 1993 at the University of Virginia; her dissertation, Solution of Convective-Diffusive Flow Problems with Newton-Like Methods, was supervised by James McDonough Ortega. She was chair of the SIAM Activity Group on Computational Science and Engineering for 2015–2016.
|
|
In the past few years, ULS has been used with great insight to analyze the molecular activation and the electron-ion recombination modes, and to determine the conditions for their activation: diffusive processes have also been considered. However, research on these subjects is still ongoing and our understanding of the elementary processes involved in a detached plasma is still far from being satisfactory.
|
|
The finite water content method lacks the effect of soil water diffusion. This omission does not affect the accuracy of flux calculations using the method because the mean of the diffusive flux is small. Practically, this means that the shape of the wetting front plays no role in driving the infiltration. The method is thus far limited to 1-D in practical applications.
|
|
Hysteresis, in this case, refers to the restructuring of the adhesive interface over some period of time, with the result being that the work needed to separate two surfaces is greater than the work that was gained by bringing them together (W > γ1 \+ γ2). For the most part, this is a phenomenon associated with diffusive bonding. The more time is given for a pair of surfaces exhibiting diffusive bonding to restructure, the more diffusion will occur, the stronger the adhesion will become. The aforementioned reaction of certain polymer-on- polymer surfaces to ultraviolet radiation and oxygen gas is an instance of hysteresis, but it will also happen over time without those factors. In addition to being able to observe hysteresis by determining if W > γ1 \+ γ2 is true, one can also find evidence of it by performing “stop-start” measurements.
|
|
It is (in principle) easy to measure whether or not two regions (for example, two glasses of water) have the same electrochemical potential for a certain chemical species (for example, a solute molecule): Allow the species to freely move back and forth between the two regions (for example, connect them with a semi-permeable membrane that lets only that species through). If the chemical potential is the same in the two regions, the species will occasionally move back and forth between the two regions, but on average there is just as much movement in one direction as the other, and there is zero net migration (this is called "diffusive equilibrium"). If the chemical potentials of the two regions are different, more molecules will move to the lower chemical potential than the other direction. Moreover, when there is not diffusive equilibrium, i.e.
|
|
This impact hypothesis is also used in some attempts to explain the planet's axial tilt. Another hypothesis is that some form of barrier exists in Uranus's upper layers that prevents the core's heat from reaching the surface. For example, convection may take place in a set of compositionally different layers, which may inhibit the upward heat transport; perhaps double diffusive convection is a limiting factor.
|
|
Geophysical imaging techniques have been applied to alpine rock glaciers to better understand mountain permafrost and perform hazard-mitigation measures. The types of geophysical imaging used include: diffusive electromagnetic, geoelectric, seismic tomography, and ground- penetrating radar. In fact, the first use of ground-penetrating radar was to determine a glacier's depth in 1929. Two dimensional geophysical imaging techniques have recently allowed for 2D imaging of mountain permafrost.
|
|
Due to their underwater environment, aquatic plants have limited access to carbon and experience reduced light levels. Aquatic plants have DBLs (diffusive boundary layers) that vary based on the leaves' thickness and density. DBLs are the main factor responsible for the lack of carbon fixation in aquatic plants. Due to this reduced ability to collect nutrients, aquatic plants have adapted various mechanisms to maximize absorption.
|
|
The two main phenomena affecting photon migration in diffusive media are absorption and scattering. Scattering is caused by microscopic refractive index changes due to the structure of the media. Absorption, on the other hand, is caused by a radiative or non-radiative transfer of light energy on interaction with absorption centers such as chromophores. Both absorption and scattering are described by coefficients \mu_aand \mu_s respectively.
|
|
This experiment consisted of a lithographically defined narrow island connected to the leads via a pair of nanoconstrictions. While the device operated in a diffusive regime the constrictions would pin domain walls, resulting in a giant magnetoresistance signal. When the device operates in a tunnelling regime another magnetoresistance effect is observed, discussed below. A furtherproperty of domain walls is that of current induced domain wall motion.
|
|
The AMoN measures ambient ammonia gas concentrations over a two-week period via a Radiello®-passive sampler, which is a simple diffusive sampler that offers higher capacity and faster sampling rates than other devices. Therefore, AMoN can provide reliable data to aid in meeting air quality policies and administration needs. AMoN collects data biweekly to determine the spatial variability and seasonality of ammonia concentrations.
|
|
Burdige, D. J., and Komada, T. (2014). “Sediment pore waters,” in Biogeochemistry of Marine Dissolved Organic Matter, eds D. A. Hansen and C. A. Carlson (Cambridge, MA: Academic Press), 535–577. doi: 10.1016/B978-0-12-405940-5.00012-1 This estimate is based on calculated diffusive fluxes and does not include resuspension events which also releases DOC Komada, T., and Reimers, C. E. (2001).
|
|
The tracking of individual rays across multiple reflection is not computational feasible because of the proliferation of trajectories. Instead, a better approach is tracking densities of rays propagated by a transfer operator. This forms the basis of the Dynamical Energy Analysis (DEA) method introduced in reference. DEA can be seen as an improvement over SEA where one lifts the diffusive field and the well separated subsystem assumption.
|
|
This race is considered as one of the toughest technical challenges race cars can face in the world. In addition, hydrogen is known to be as much as four times more diffusive than natural gas. This means that if hydrogen gas is leaking, it will quickly go up in the atmosphere. Furthermore, when hydrogen burns, its radiant heat is just one-tenth that of a hydrocarbon fire.
|
|
A flame may exhibit intrinsic instabilities of several kinds when one or more of the physico-chemical balances associated with its propagation is offset. In premixed flames, the primary instability is a hydrodynamic instability — known as the Darrieus-Landau instability — which results from thermal expansion across the flame interface. In non-premixed (diffusion) flames, thermo- diffusive instabilities are predominant while the hydrodynamic instability plays a secondary role.
|
|
Diffusive ventilation is simply a form of continuous gas exchange that occurs by diffusion rather than physically taking in the oxygen. Some species of insect that are submerged also have adaptations to aid in respiration. As larvae, many insects have gills that can extract oxygen dissolved in water, while others need to rise to the water surface to replenish air supplies, which may be held or trapped in special structures.
|
|
Anderson and Topshop scheduled another collaboration to launch a year later, with the release coming in February 2013. Later that year, Donatella Versace enlisted him to replace Christopher Kane at Versace’s diffusive line Versus, where he showcased his first collection in June at New York’s Lexington Armoury. In September 2013, LVMH took a minority stake in JW Anderson and named Anderson as new creative director for Spanish luxury house LOEWE.
|
|
In 1945 Prigogine (see also Prigogine (1947)Prigogine, I. (1947). Étude thermodynamique des Phenomènes Irreversibles, Desoer, Liege.) proposed a “Theorem of Minimum Entropy Production” which applies only to the purely diffusive linear regime, with negligible inertial terms, near a stationary thermodynamically non-equilibrium state. Prigogine's proposal is that the rate of entropy production is locally minimum at every point. The proof offered by Prigogine is open to serious criticism.
|
|
Advection is sometimes confused with the more encompassing process of convection which is the combination of advective transport and diffusive transport. In meteorology and physical oceanography, advection often refers to the transport of some property of the atmosphere or ocean, such as heat, humidity (see moisture) or salinity. Advection is important for the formation of orographic clouds and the precipitation of water from clouds, as part of the hydrological cycle.
|
|
Mass transfer is the net movement of mass from one location, usually meaning stream, phase, fraction or component, to another. Mass transfer occurs in many processes, such as absorption, evaporation, drying, precipitation, membrane filtration, and distillation. Mass transfer is used by different scientific disciplines for different processes and mechanisms. The phrase is commonly used in engineering for physical processes that involve diffusive and convective transport of chemical species within physical systems.
|
|
The diffuson is a mathematical object, which often appears in the theory of disordered electronic systems (a part of condensed matter physics). In a disordered system, the motion of an electron is not ballistic, but diffusive: i.e., the electron does not move along a straight line, but experiences a series of random scatterings off of impurities. This random motion (diffusion) is described by a differential equation, known as the diffusion equation.
|
|
He considers a conceptual small cell in a situation of continuous-flow as a system defined in the so-called Lagrangian way, moving with the local center of mass. The flow of matter across the boundary is zero when considered as a flow of total mass. Nevertheless, if the material constitution is of several chemically distinct components that can diffuse with respect to one another, the system is considered to be open, the diffusive flows of the components being defined with respect to the center of mass of the system, and balancing one another as to mass transfer. Still there can be a distinction between bulk flow of internal energy and diffusive flow of internal energy in this case, because the internal energy density does not have to be constant per unit mass of material, and allowing for non- conservation of internal energy because of local conversion of kinetic energy of bulk flow to internal energy by viscosity.
|
|
Skolnick was first to demonstrate that the library of single domain protein structures is likely complete and that the observed folds in nature arise from the confinement of dense polymer chains. He further demonstrated that the confinement of these dense polymer chains plus hydrodynamic interactions were the dominant contributor to diffusive processes in cells. Moreover, that the hydrodynamic interactions introduced large scale temporal and spatial correlations that may have important functional consequences.
|
|
There are many different patterns of gas exchange demonstrated by different groups of insects. Gas exchange patterns in insects can range from continuous and diffusive ventilation, to discontinuous gas exchange. During continuous gas exchange, oxygen is taken in and carbon dioxide is released in a continuous cycle. In discontinuous gas exchange, however, the insect takes in oxygen while it is active and small amounts of carbon dioxide are released when the insect is at rest.
|
|
Next, proteins undergo a nucleation phase, where submicroscopic sized protein aggregates, or particles, are generated. Growth of these particles is under Brownian diffusion control. Once the particles reach a critical size (0.1 µm to 10 µm for high and low shear fields, respectively), by diffusive addition of individual protein molecules to it, they continue to grow by colliding into each other and sticking or flocculating. This phase occurs at a slower rate.
|
|
377x377px Breathless Maiden Lane was an installation in the atrium of 125 Maiden Lane, a glass, marble and granite space in New York's Financial District. Amorós used LED lights, diffusive material, and "bubble" sculptures. The LED tubing was an allusion to reeds that grow in northern Peru, and the bubbles meant to suggest the artificial islands of Lake Titicaca. The light installation is a part of VIP The Armory Show (art fair) event.
|
|
The bifurcation has found application in, amongst other places, slow-fast models of computational neuroscience. The possibility of the phenomenon was raised by David Ruelle and Floris Takens in 1971, and explored by R.L. Devaney and others in the following decade. More compelling analysis was not performed until the 1990s. This bifurcation has also been found in the context of fluid dynamics, namely in double-diffusive convection of a small Prandtl number fluid.
|
|
Baines attended Royal Australian Naval College from 1955 till 1958 and studied at Melbourne High School in 1959. He received his Bachelor of Arts degree with honours in Mathematics and Bachelor of Science degree in Physics in 1963 and 1964, respectively, from Melbourne University. He then moved to the United Kingdom where he completed his doctorate in Geophysical Fluid Dynamics from Cambridge University in 1969, on rotating and stratified flows, and double-diffusive convection.
|
|
This allows for higher concentrations of nutrients inside the vacuole than would be allowed by strictly longitudinal cytoplasmic flows. Goldstein also demonstrated the faster the cytoplasmic flow along these trajectories, the larger the concentration gradient that arises, and the larger diffusive nutrient transport into the storage vacuole that occurs. The enhanced nutrient transport into the vacuole leads to striking differences in growth rate and overall growth size. Experiments have been performed in Arabidopsis thaliana.
|
|
A wall selectively permeable only to a pure substance can put the system in diffusive contact with a reservoir of that pure substance in the surroundings. Then a process is possible in which that pure substance is transferred between system and surroundings. Also, across that wall a contact equilibrium with respect to that substance is possible. By suitable thermodynamic operations, the pure substance reservoir can be dealt with as a closed system.
|
|
Spiracles are closed and opened by means of valves and can remain partly or completely closed for extended periods in some insects, which minimises water loss. There are many different patterns of gas exchange demonstrated by different groups of insects. Gas exchange patterns in insects can range from continuous, diffusive ventilation, to discontinuous gas exchange. Terrestrial and a large proportion of aquatic insects perform gaseous exchange as previously mentioned under an open system.
|
|
Grain boundary sliding is a plastic deformation mechanism where crystals can slide past each other without friction and without creating significant voids as a result of diffusion. The deformation process associated with this mechanism is referred to as granular flow. The absence of voids results from solid-state diffusive mass transfer, locally enhanced crystal plastic deformation, or solution and precipitation of a grain boundary fluid. This mechanism operates at a low strain rate produced by neighbor switching.
|
|
In the quantum extension of the flow, however, the density of points in phase space is not conserved; the probability fluid appears "diffusive" and compressible. The concept of quantum trajectory is therefore a delicate issue here. See the movie for the Morse potential, below, to appreciate the nonlocality of quantum phase flow. N.B. Given the restrictions placed by the uncertainty principle on localization, Niels Bohr vigorously denied the physical existence of such trajectories on the microscopic scale.
|
|
Differential equations are essential tools in mathematical modelling. Most physical systems are described in terms of mathematical models that include convective and diffusive transport of some variables. Finite difference methods are amongst the most popular methods that have been applied most frequently in solving such differential equations. A finite difference scheme is compact in the sense that the discretised formula comprises at most nine point stencils which includes a node in the middle about which differences are taken.
|
|
The dilute nature of the pelagic marine environment promotes large diffusive losses and renders the efficiency of the normal siderophore-based iron uptake strategies problematic. However, many heterotrophic marine bacteria do produce siderophores, albeit with properties different from those produced by terrestrial organisms. Many marine siderophores are surface-active and tend to form molecular aggregates, for example aquachelins. The presence of the fatty acyl chain renders the molecules with a high surface activity and an ability to form micelles.
|
|
Traditionally, mannitol is extracted by the Soxhlet extraction, using ethanol, water, and methanol to steam and then hydrolysis of the crude material. The mannitol is then recrystallized from the extract, generally resulting in yields of about 18% of the original natural product. Another method of extraction is using supercritical and subcritical fluids. These fluids are at such a stage that no difference exists between the liquid and gas stages, so are more diffusive than normal fluids.
|
|
On the other hand, the DMM assumes scattering at the interface is diffusive, which is accurate for interfaces with characteristic roughness at elevated temperatures. Molecular dynamics (MD) simulations are a powerful tool to investigate interfacial thermal resistance. Recent MD studies have demonstrated that the solid-liquid interfacial thermal resistance is reduced on nanostructured solid surfaces by enhancing the solid-liquid interaction energy per unit area, and reducing the difference in vibrational density of states between solid and liquid.
|
|
Fermi acceleration,Krymskii G.F. (1977) Dokl. Akad. Nauk SSSR 234, 1306 sometimes referred to as diffusive shock acceleration (a subclass of Fermi accelerationOn the Origin of the Cosmic Radiation, E. Fermi, Physical Review 75, pp. 1169-1174, 1949), is the acceleration that charged particles undergo when being repeatedly reflected, usually by a magnetic mirror (see also Centrifugal mechanism of acceleration). This is thought to be the primary mechanism by which particles gain non thermal energies in astrophysical shock waves.
|
|
Uniform synchrony, waves and spirals can readily be observed in two-dimensional Kuramoto networks with diffusive local coupling. The stability of waves in these models can be determined analytically using the methods of Turing stability analysis. Uniform synchrony tends to be stable when the local coupling is everywhere positive whereas waves arise when the long-range connections are negative (inhibitory surround coupling). Waves and synchrony are connected by a topologically distinct branch of solutions known as ripple.
|
|
A dynamo converts kinetic energy into electric-magnetic energy. An electrically conducting fluid with shear or more complicated motion, such as turbulence, can temporarily amplify a magnetic field through Lenz's law: fluid motion relative to a magnetic field induces electric currents in the fluid that distort the initial field. If the fluid motion is sufficiently complicated, it can sustain its own magnetic field, with advective fluid amplification essentially balancing diffusive or ohmic decay. Such systems are called self-sustaining dynamos.
|
|
Diffuse optical mammography, or simply optical mammography, is an emerging imaging technique that enables the investigation of the breast composition through spectral analysis. It combines in a single non-invasive tool the capability to implement breast cancer risk assessment, lesion characterization, therapy monitoring and prediction of therapy outcome. It is an application of diffuse optics, which studies light propagation in strongly diffusive media, such as biological tissues, working in the red and near- infrared spectral range, between 600 and 1100 nm.
|
|
The minority carrier diffusion length is critical in determining the performance of devices such as photoconducting detectors and bipolar transistors. In both cases the ratio of the diffusion length to the device dimensions determines the gain. In photovoltaic devices, photodiodes and field-effect transistors, the drift behavior due to built-in fields is more important under typical conditions than the diffusive behavior. Even so the SPV is a convenient method of measuring the density of impurity-derived recombination centers that limit device performance.
|
|
Bell was awarded the 2014 Fred Hoyle Medal and Prize of the Institute of Physics "for elucidating the origin and impact of cosmic rays and for his seminal contributions to electron energy transport in laboratory plasmas". In 2016 he was awarded the Eddington Medal of the Royal Astronomical Society for "his development of the theory of the acceleration of charged particles in astrophysics, known as Diffusive Shock Acceleration". He was elected a Fellow of the Royal Society (FRS) in 2017.
|
|
The study of long chain polymers has been a source of problems within the realms of statistical mechanics since about the 1950s. One of the reasons however that scientists were interested in their study is that the equations governing the behavior of a polymer chain were independent of the chain chemistry. What is more, the governing equation turns out to be a random walk, or diffusive walk, in space. Indeed, the Schrödinger equation is itself a diffusion equation in imaginary time, t' = it.
|
|
K promotes the synthesis of carbon dioxide fixing enzymes, decreases the diffusive resistance of CO2 in the leaf and activates various enzyme reaction systems. Potassium is highly mobile in plants. Leaf potassium content decreases rapidly during fruiting because the fruit requires substantial K. Symptoms of K deficiency include lower growth rates, smaller fruit and seed sizes, reduced root systems, disease and winterkill susceptibility and lower moisture and nitrogen absorption and content. Chlorosis starts from old leaves after K moves to other plant parts.
|
|
The local mean magnetic field scales as k^{-1/3} , substitution of which in Dobrowolny's equation yields Kolmogorov's energy spectrum for MHD turbulence. Renormalization group analysis have been also performed for computing the renormalized viscosity and resistivity. It was shown that these diffusive quantities scale as k^{-4/3} that again yields k^{-5/3} energy spectra consistent with Kolmogorov-like model for MHD turbulence. The above renormalization group calculation has been performed for both zero and nonzero cross helicity.
|
|
In addition to general severe symptoms, one unusual case reported that the severe perineal infection of a led to acute large intestinal obstruction. Moreover, other rare cases also reported the infections happened on other anatomical regions such as the colon in the case of gastrointestinal basidiobolomycosis. Infections may be associated with a diffusive bluish pigmentation generally associated with swelling. Joint function is often not affected; however, a few other cases reported the subcutaneous infection transfect local muscle tissues and lymph nodes.
|
|
By means of different factors, such as diffusion and steric, hydrodynamic, dielectric and other effects, or a combination thereof, particles (<1 μm in diameter) with different dielectric or diffusive properties attain different positions away from the chamber wall, which, in turn, exhibit different characteristic concentration profile. Particles that move further away from the wall reach higher positions in the parabolic velocity profile of the liquid flowing through the chamber and will be eluted from the chamber at a faster rate.
|
|
A random laser (RL) is a laser in which optical feedback is provided by scattering particles.M. A. Noginov Solid-state random lasers (Springer, New York, 2005). . As in conventional lasers, a gain medium is required for optical amplification. However, opposite to Fabry–Pérot cavities and distributed feedback laser, neither reflective surfaces nor distributed periodic structures are used in RLs, as light is confined in an active region by diffusive elements that either can or cannot be spatially distributed inside the gain medium.
|
|
For example, cross-linked polymers are less capable of diffusion and interdigitation because they are bonded together at many points of contact, and are not free to twist into the adjacent surface. Uncrosslinked polymers (thermoplastics), on the other hand are freer to wander into the adjacent phase by extending tails and loops across the interface. Another circumstance under which diffusive bonding occurs is “scission”. Chain scission is the cutting up of polymer chains, resulting in a higher concentration of distal tails.
|
|
The simplest theory to predict the behaviour of detonations in gases is known as Chapman-Jouguet (CJ) theory, developed around the turn of the 20th century. This theory, described by a relatively simple set of algebraic equations, models the detonation as a propagating shock wave accompanied by exothermic heat release. Such a theory confines the chemistry and diffusive transport processes to an infinitesimally thin zone. A more complex theory was advanced during World War II independently by Zel'dovich, von Neumann, and W. Doering.
|
|
Time-domain diffuse optics or time-resolved functional near-infrared spectroscopy is branch of functional near-Infrared spectroscopy which deals with light propagation in diffusive media. There are three main approaches to diffuse optics namely continuous wave (CW), frequency domain (FD) and time- domain (TD). Biological tissue in the range of red to near-infrared wavelengths are transparent to light and can be used to probe deep layers of the tissue thus enabling various in vivo applications and clinical trials.
|
|
Since 2016 Caro is president of the Society of German Chemists GDCh district Hannover.GDCh-Presidents of the German districts . In 2019 he was awarded with the literature price of chemical industry (Fonds der Chemischen Industrie) together with his co-authors Armin Bunde, Jörg Kärger und Gero Vogl for the book „Diffusive Spreading in Nature, Technology and Society“.Press release of VCI about literature prize 2019 . Caro is author of 380 scientific publications, 10 book chapters, 43 patents and patent applications.
|
|
Glass micropipettes are filled with an ionic solution to make them conductive; a silver-silver chloride (Ag-AgCl) electrode is dipped into the filling solution as an electrical terminal. Ideally, the ionic solutions should have ions similar to ionic species around the electrode; the concentration inside the electrode and surrounding fluid should be the same. Additionally, the diffusive characteristics of the different ions within the electrode should be similar. The ion must also be able to "provide current carrying capacity adequate for the needs of the experiment".
|
|
Dew drops adhering to a spider web frog on a wet vertical glass surface. Adhesion is the tendency of dissimilar particles or surfaces to cling to one another (cohesion refers to the tendency of similar or identical particles/surfaces to cling to one another). The forces that cause adhesion and cohesion can be divided into several types. The intermolecular forces responsible for the function of various kinds of stickers and sticky tape fall into the categories of chemical adhesion, dispersive adhesion, and diffusive adhesion.
|
|
The heightened concentration of these chain ends gives rise to a heightened concentration of polymer tails extending across the interface. Scission is easily achieved by ultraviolet irradiation in the presence of oxygen gas, which suggests that adhesive devices employing diffusive bonding actually benefit from prolonged exposure to heat/light and air. The longer such a device is exposed to these conditions, the more tails are scissed and branch out across the interface. Once across the interface, the tails and loops form whatever bonds are favorable.
|
|
The lungs, lymph nodes, and mucous membrane of the mouth are the most frequently infected tissues. The pathological features of paracoccidioidomycosis are similar to those seen in coccidioidomycosis and blastomycosis. However, in the former, the lesions first appear in the lymphoid tissue and then extend to mucous membranes, producing localized to diffusive tissue necrosis of the lymph nodes. The typically extensive involvement of lymphoid tissue and the limited occurrence of the gastrointestinal tract, bone and prostate set the clinical picture of paracoccidioidomycosis apart from that of blastomycosis.
|
|
In this case the magnetic mirror is a moving interstellar magnetized cloud. In a random motion environment, Fermi argued, the probability of a head-on collision is greater than a head-tail collision, so particles would, on average, be accelerated. This random process is now called second-order Fermi acceleration, because the mean energy gain per bounce depends on the mirror velocity squared, \beta_m^2. The resulting energy spectrum anticipated from this physical setup, however, is not universal as in the case of diffusive shock acceleration.
|
|
Most species of aphids, at all stages of development, move about over the surface of their host plants and even between adjacent plants. These local movements result in slow diffusive dispersal. In contrast, aphids also show persistent 'straightened out' movements during which their vegetative responses are depressed; these movements are a means of transport over larger distances. Local 'trivial' movements and distant 'migratory' movements can be recognized, and it is possible that they are the extremes of a continuum of movement that disperses all species of aphids.
|
|
In physics and engineering, the Fourier number (Fo) or Fourier modulus, named after Joseph Fourier, is a dimensionless number that characterizes transient heat conduction. Conceptually, it is the ratio of diffusive or conductive transport rate to the quantity storage rate, where the quantity may be either heat (thermal energy) or matter (particles). The number derives from non- dimensionalization of the heat equation (also known as Fourier's Law) or Fick's second law and is used along with the Biot number to analyze time dependent transport phenomena.
|
|
Facilitated diffusion in cell membrane, showing ion channels and carrier proteins Facilitated diffusion (also known as facilitated transport or passive-mediated transport) is the process of spontaneous passive transport (as opposed to active transport) of molecules or ions across a biological membrane via specific transmembrane integral proteins. Being passive, facilitated transport does not directly require chemical energy from ATP hydrolysis in the transport step itself; rather, molecules and ions move down their concentration gradient reflecting its diffusive nature. Insoluble molecules diffusing through an integral protein. Facilitated diffusion is different from simple diffusion in several ways.
|
|
The computational core of MIKE 11 is a hydrodynamic simulation engine, and this is complemented by a wide range of additional modules and extensions covering almost all conceivable aspects of river modeling. HD module: provides fully dynamic solution to the complete nonlinear 1-D Saint Venant equations, diffusive wave approximation and kinematic wave approximation, Muskingum method and Muskingum-Cunge method for simplified channel routing. It can automatically adapt to subcritical flow and supercritical flow. It has ability to simulate standard hydraulic structures such as weirs, culverts, bridges, pumps, energy loss and sluice gates.
|
|
The early lines of research and applications of the FPM to fluid flow problems are summarized in (Fischer, 1996). There, convective-diffusive problems were studied using LSQ and WLSQ polynomial approximations. The study focused on the effects of the cloud of points and weighting functions on the accuracy of the local approximation, which helped to understand the basic behavior of the FPM. The results showed that the 1D FPM approximation leads to discrete derivative forms similar to those obtained with central difference approximations, which are second-order accurate.
|
|
He has authored more than 200 mathematical research papers centered around partial differential equations. He has made contributions to the understanding of the asymptotic and qualitative behavior of solutions to nonlinear diffusion equations, particularly through the use of entropy methods and gradient flow techniques. He obtained results on the exponential convergence to equilibrium of the porous medium equation by using an analogue of the Bakry-Émery method . He has also worked on kinetic and diffusive models in mathematical biology describing chemotaxis, flocking and swarming behavior of interacting agents, as well as on computational neuroscience.
|
|
The terms 'classical irreversible thermodynamics' and 'local equilibrium thermodynamics' are sometimes used to refer to a version of non- equilibrium thermodynamics that demands certain simplifying assumptions, as follows. The assumptions have the effect of making each very small volume element of the system effectively homogeneous, or well-mixed, or without an effective spatial structure, and without kinetic energy of bulk flow or of diffusive flux. Even within the thought-frame of classical irreversible thermodynamics, care is needed in choosing the independent variablesPrigogine, I., Defay, R. (1950/1954). Chemical Thermodynamics, Longmans, Green & Co, London, page 1.
|
|
The developing limb has to align itself in relation to three axes of symmetry. These are the craniocaudal (head to tail), dorsoventral (back to front), and proximodistal (near to far) axes. Many investigations into the development of the limb skeletal pattern have been influenced by the positional information concept proposed by Lewis Wolpert in 1971. In tune with this idea, efforts have been made to identify diffusive signaling molecules (morphogens) that traverse orthogonal axes of developing limbs and determine locations and identities of skeletal elements in a concentration-dependent fashion.
|
|
Biological flight data can also apparently be mimicked by other models such as composite correlated random walks, which grow across scales to converge on optimal Lévy walks. Composite Brownian walks can be finely tuned to theoretically optimal Lévy walks but they are not as efficient as Lévy search across most landscapes types, suggesting selection pressure for Lévy walk characteristics is more likely than multi-scaled normal diffusive patterns. Efficient routing in a network can be performed by links having a Levy flight length distribution with specific values of alpha.
|
|
Convection in fluids is driven by density variations within them under the influence of gravity. These density variations may be caused by gradients in the composition of the fluid, or by differences in temperature (through thermal expansion). Thermal and compositional gradients can often diffuse with time, reducing their ability to drive the convection, and requiring that gradients in other regions of the flow exist in order for convection to continue. A common example of double diffusive convection is in oceanography, where heat and salt concentrations exist with different gradients and diffuse at differing rates.
|
|
Further investigation of the SCN as a central structure of circadian rhythms by Silver, et al. found that the SCN can control circadian rhythmicity by a diffusive signal. They transplanted the SCN as previously done by Menaker, but they encapsulated the graft thus preventing outgrowth by mutant SCN neurons. Even with the SCN restrained in this way the wild type hamster displayed a shorter period consistent with the period of the SCN donated by the mutant tau hamster, suggesting the SCN emits diffusable factors to control circadian rhythms.
|
|
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.
|
|
In structural geology and diagenesis, pressure solution or pressure dissolution is a deformation mechanism that involves the dissolution of minerals at grain-to-grain contacts into an aqueous pore fluid in areas of relatively high stress and either deposition in regions of relatively low stress within the same rock or their complete removal from the rock within the fluid. It is an example of diffusive mass transfer. The detailed kinetics of the process was reviewed by Rutter (1976), and since then such kinetics has been used in many applications in earth sciences.
|
|
Despite the nuclear fusion occurring in the core, the majority of solar material is representative of the material that formed the solar system. By studying SEP's isotopic composition, scientists can indirectly measure the material that formed the solar system. Two main mechanisms of acceleration are possible: diffusive shock acceleration (DSA, an example of second-order Fermi acceleration) or the shock-drift mechanism. SEPs can be accelerated to energies of several tens of MeV within 5–10 solar radii (5% of the Sun–Earth distance) and can reach Earth in a few minutes in extreme cases.
|
|
The effect is quantum- mechanical in nature and has the following origin: In a disordered electronic system, the electron motion is diffusive rather than ballistic. That is, an electron does not move along a straight line, but experiences a series of random scatterings off impurities which results in a random walk. The resistivity of the system is related to the probability of an electron to propagate between two given points in space. Classical physics assumes that the total probability is just the sum of the probabilities of the paths connecting the two points.
|
|
This is a reason to think of heat as a specialized concept that relates primarily and precisely to closed systems, and applicable only in a very restricted way to open systems. In many writings in this context, the term "heat flux" is used when what is meant is therefore more accurately called diffusive flux of internal energy; such usage of the term "heat flux" is a residue of older and now obsolete language usage that allowed that a body may have a "heat content".Gyarmati, I. (1970), p. 68.
|
|
This is to be contrasted with the highly sensitive and fading footprint of hyperbolic LCSs away from strongly hyperbolic regions in diffusive tracer patterns. Under variable endpoint boundary conditions, initial positions of parabolic LCSs turn out to be alternating chains of shrink lines and stretch lines that connect singularities of these line fields. These singularities occur at points where \lambda_1(x_0)=\lambda_2(x_0), and hence no infinitesimal deformation takes place between the two time instances t_0 and t_1. Fig. 14b shows an example of parabolic LCSs in Jupiter's atmosphere, located using this variational theory.
|
|
In structural geology and diagenesis, pressure solution or pressure dissolution is a deformation mechanism that involves the dissolution of minerals at grain-to- grain contacts into an aqueous pore fluid in areas of relatively high stress and either deposition in regions of relatively low stress within the same rock or their complete removal from the rock within the fluid. It is an example of diffusive mass transfer. Stylolites are formed by this process. Stylolites can be classified according to their geometry or their orientation and relationship to bedding.
|
|
The HGS model is a three-dimensional control-volume finite element simulator which is designed to simulate the entire terrestrial portion of the hydrologic cycle. It uses a globally implicit approach to simultaneously solve the 2D diffusive-wave equation and the 3D form of Richards’ equation. HGS also dynamically integrates key components of the hydrologic cycle such as evaporation from bare soil and water bodies, vegetation-dependent transpiration with root uptake, snowmelt and soil freeze/thaw. Features such as macro pores, fractures, and tile drains can either be incorporated discretely or using a dual-porosity, dual permeability formulation.
|
|
Schematic illustration of an initially sharp > concentration gradient between mineral growth zones (blue dashed line) and > subsequent measured diffusive gradient (red lines).Geologists apply > diffusion theory to natural minerals in order to understand the thermal > histories of igneous and metamorphic systems. Diffusion profiles of a given > element are measured between growth zones of a single mineral, or at the > interface between two different minerals. In order to measure a diffusion > profile in a single crystal, geologists measure one-dimesional transects > using high spatial resolution instruments such as the scanning electron > microscope, electron microprobe, secondary ion mass spectrometry or > nanoscale secondary ion mass spectrometry.
|
|
The medium's anisotropy is represented by the factor g, which is the average cosine of the angular deflection. Light propagation through highly diffusive media is typically described through the heuristic approach of the radiative transport theory, sided by the so-called “diffusion approximation”: scattering is assumed to be isotropic and strongly dominant over absorption. This is fairly accurate for example for the breast tissue, in the red and near infrared spectral range (between 600 and 1100 nm), known also as "therapeutic window". In the therapeutic window, light can penetrate a few centimetres, so that it can explore the volume at exam.
|
|
To study finite-size effects in transport such as the transition from diffusive to ballistic transport requires the precise placement and addressing of nanoscale electrodes, typically fabricated using electron beam lithography. Structural characterization of CNTs using transmission electron microscopy has been shown to be a useful method for structures identification and measures. Results have been reported with resolutions down to about 1 nm and very good material contact. Due to the experimental difficulties of contacting nano-objects inside an electron microscope, there have only been few attempts to combine transmission electron microscopy structural characterization with in-situ electrical transport measurements.
|
|
It has been shown that there is an abrupt transition between these two regimes. In fact, all network descriptors depending on some diffusive process, from centrality measures to community detection, are affected by the layer-layer coupling. For instance, in the case of community detection, low coupling (where information from each layer separately is more relevant than the overall structure) favors clusters within layers, whereas high coupling (where information from all layer simultaneously is more relevant than the each layer separately) favors cross- layer clusters. Diffusion reaction process on a multilayer system has been studied by Lazaridis et al.
|
|
Schmittmann was named a Fellow of the American Physical Society (APS) in 2004, after a nomination from the APS Topical Group on Statistical & Nonlinear Physics, for "seminal and sustained research on fundamental and applied problems in non- equilibrium statistical physics, in particular driven diffusive systems". In 2010, the Southeastern Section of the APS gave her their for research excellence. She became a Fellow of the American Association for the Advancement of Science in 2015 for "seminal and sustained research on fundamental and applied problems in nonequilibrium statistical physics, and for contributions to administration and to increasing diversity in STEM".
|
|
The thermophoretic force has a number of practical applications. The basis for applications is that, because different particle types move differently under the force of the temperature gradient, the particle types can be separated by that force after they've been mixed together, or prevented from mixing if they're already separated. Impurity ions may move from the cold side of a semiconductor wafer towards the hot side, since the higher temperature makes the transition structure required for atomic jumps more achievable. The diffusive flux may occur in either direction (either up or down the temperature gradient), dependent on the materials involved.
|
|
The mole fraction of A at the upper mouth of the tube is zero, as a consequence of the gas flow. At the interface between A and B the flux of B is zero (because it is insoluble in A) and the mole fraction is the equilibrium value. The flux of B, denoted NB, is thus zero throughout the tube, its diffusive flux downward (along its concentration gradient) is balanced by its convective flux upward caused by A. Applying these assumptions, the system can be modelled using Fick's laws of diffusion or as Maxwell–Stefan diffusion.
|
|
During the mission the crew deployed two satellites, Canada's Anik D-2 (Telesat H) and Hughes' LEASAT-1 (Syncom IV-1), and operated the 3M Company's Diffusive Mixing of Organic Solutions experiment. In the first space salvage attempt in history, Allen and Gardner performed spacewalks and successfully retrieved for return to Earth the Palapa B-2 and Westar VI communications satellites. STS 51-A completed 127 orbits of the Earth in 192 hours before landing at Kennedy Space Center, Florida, on November 16, 1984. With the completion of this flight Allen logged a total of 314 hours in space.
|
|
Numerical simulations results by Singh and Srinivasan show concentration fields at different Rayleigh numbers for fixed value of . The parameters are: (a) RaT = 7×108 , t=1.12×10−2, (b) RaT =3.5×108, t=1.12×10−2, (c) RaT =7×106, t=1.31×10−2, (d) RaT=7×105, t=3.69×10−2. It is seen from the figure that finger characteristics such as width, evolution pattern are a function of Rayleigh numbers. Double diffusive convection is a fluid dynamics phenomenon that describes a form of convection driven by two different density gradients, which have different rates of diffusion.
|
|
The Goldstein model predicts enhanced transport (over transport characterized by strictly longitudinal cytoplasmic flow) into the vacuolar cavity due to the complicated flow trajectories arising from the cytoplasmic streaming. Although, a nutrient concentration gradient would result from longitudinally uniform concentrations and flows, the complicated flow trajectories predicted produce a larger concentration gradient across the vacuolar membrane. By Fick's laws of diffusion, it is known that larger concentration gradients lead to larger diffusive flows. Thus, the unique flow trajectories of the cytoplasmic flow in Chara coralina lead to enhanced nutrient transport by diffusion into the storage vacuole.
|
|
A number of formulations of the phase-field model are based on a free energy function depending on an order parameter (the phase field) and a diffusive field (variational formulations). Equations of the model are then obtained by using general relations of statistical physics. Such a function is constructed from physical considerations, but contains a parameter or combination of parameters related to the interface width. Parameters of the model are then chosen by studying the limit of the model with this width going to zero, in such a way that one can identify this limit with the intended sharp interface model.
|
|
The total transport rate of the species is then given by a summation of the Stefan flow and diffusive contributions. An example of the Stefan flow occurs when a droplet of liquid evaporates in air. In this case, the vapor/air mixture surrounding the droplet is the flowing fluid, and liquid/vapor boundary of the droplet is the interface. As heat is absorbed by the droplet from the environment, some of the liquid evaporates into vapor at the surface of the droplet, and flows away from the droplet as it is displaced by additional vapor evaporating from the droplet.
|
|
Passive or "diffusive" air sampling depends on meteorological conditions such as wind to diffuse air pollutants to a sorbent medium. Passive samplers have the advantage of typically being small, quiet, and easy to deploy, and they are particularly useful in air quality studies that determine key areas for future continuous monitoring. Air pollution can also be assessed by biomonitoring with organisms that bioaccumulate air pollutants, such as lichens, mosses, fungi, and other biomass. One of the benefits of this type of sampling is how quantitative information can be obtained via measurements of accumulated compounds, representative of the environment from which they came.
|
|
The use of passive samplers greatly reduces the cost and the need of infrastructure on the sampling location. Passive samplers are semi-disposable and can be produced at a relatively low cost, thus they can be employed in great numbers, allowing for a better cover and more data being collected. Due to being small the passive sampler can also be hidden, and thereby lower the risk of vandalism. Examples of passive sampling devices are the diffusive gradients in thin films (DGT) sampler, Chemcatcher, Polar organic chemical integrative sampler (POCIS), semipermeable membrane devices (SPMDs), stabilized liquid membrane devices (SLMDs), and an air sampling pump.
|
|
In 1830 Henson wrote The Civil, Political, and Mechanical History of the Framework-Knitters, Vol 1, but only the one volume, down to 1780, was published, due to a lack of public support. According to William Felkin, this was because of "his diffusive manner and some peculiar opinions set forth with needless prominence." He left behind him at his death the manuscripts of Notes of Inventions and Improvements of Lace Machines down to the year 1850, and some (or all) of these were published in an edition of 1970.W. Felkin, A History of... (1867), p.
|
|
These conditions have the potential to elevate brine pH and to further contribute to the creation of an extreme environment. In these conditions, high concentrations of DOM and ammonia and low concentrations of nutrients often characterize the ice matrix. High brine salinity combined with an elevated pH reduces the rate at which gases and inorganic nutrients diffuse into the ice matrix. The concentration of nutrients such as nitrate, phosphate and silicate inside the sea ice matrix relies largely on the diffusive influx from the sea ice-water interface and to some extent on the atmospheric deposits on the sea ice-air interface.
|
|
Carboxylation enzymes in the cytosol can, therefore, be kept separate from decarboxylase enzymes and RuBisCO in the chloroplasts, and a diffusive barrier can be established between the chloroplasts (which contain RuBisCO) and the cytosol. This enables a bundle-sheath-type area and a mesophyll-type area to be established within a single cell. Although this does allow a limited cycle to operate, it is relatively inefficient, with the occurrence of much leakage of from around RuBisCO. There is also evidence for the exhibiting of inducible photosynthesis by non-kranz aquatic macrophyte Hydrilla verticillata under warm conditions, although the mechanism by which leakage from around RuBisCO is minimised is currently uncertain.
|
|
This process is grain- size sensitive and occurs at low strain rates or very high temperatures, and is accommodated by migration of lattice defects from areas of low to those of high compressive stress. The main mechanisms of diffusive mass transfer are Nabarro-Herring creep, Coble creep, and pressure solution. Nabarro–herring creep, or volume diffusion, acts at high homologous temperatures and is grain size dependent with the strain-rate inversely proportional to the square of the grain size (creep rate decreases as the grain size increases). During Nabarro-Herring creep, the diffusion of vacancies occurs through the crystal lattice [microtectonics], which causes grains to elongate along the stress axis.
|
|
The reason why the precipitation temporarily or permanently stops in these regions is that the oblique, passive edges of the precipitate act as a semipermeable membrane, blocking the diffusion of the outer electrolyte . The mechanism behind the regression of the active front segments is not fully understood. It is believed that a diffusive intermediate compound forms at the active segments having reduced concentration at the sides, and a critical concentration is required for the precipitation to occur. When the outer electrolyte is poured onto the top of a gel column in a glass tube, the diffusion front takes roughly the form of a disk.
|
|
In the mathematical modeling of seismic waves, the Cagniard–De Hoop method is a sophisticated mathematical tool for solving a large class of wave and diffusive problems in horizontally layered media. The method is based on the combination of a unilateral Laplace transformation with the real-valued and positive transform parameter and the slowness field representation. It is named after Louis Cagniard and Adrianus de Hoop; Cagniard published his method in 1939, and de Hoop published an ingenious improvement on it in 1960.De Hoop, A. T. "A modification of Cagniard's method for solving seismic pulse problems". Applied Scientific Research, B8 (1960): 349–356.
|
|
Turbulence causes the air within the lower atmospheric regions below the turbopause at about 110 km to be a mixture of gases that does not change its composition. Its mean molecular weight is 29 g/mol with molecular oxygen (O2) and nitrogen (N2) as the two dominant constituents. Above the turbopause, however, diffusive separation of the various constituents is significant, so that each constituent follows its barometric height structure with a scale height inversely proportional to its molecular weight. The lighter constituent's atomic oxygen (O), helium (He), and hydrogen (H) successively dominate above about 200 km altitude and vary with geographic location, time, and solar activity.
|
|
Since the stress is now spread out over some area, the stress at any given point has less of a chance of overwhelming the total adhesive force between the surfaces. If failure does occur at an interface containing a viscoelastic adhesive agent, and a crack does propagate, it happens by a gradual process called “fingering”, rather than a rapid, brittle fracture. Stringing can apply to both the diffusive bonding regime and the chemical bonding regime. The strings of molecules bridging across the gap would either be the molecules that had earlier diffused across the interface or the viscoelastic adhesive, provided that there was a significant volume of it at the interface.
|
|
In the case of a flowing system of only one chemical constituent, in the Lagrangian representation, there is no distinction between bulk flow and diffusion of matter. Moreover, the flow of matter is zero into or out of the cell that moves with the local center of mass. In effect, in this description, one is dealing with a system effectively closed to the transfer of matter. But still one can validly talk of a distinction between bulk flow and diffusive flow of internal energy, the latter driven by a temperature gradient within the flowing material, and being defined with respect to the local center of mass of the bulk flow.
|
|
The magnetic Reynolds number has a similar form to both the Péclet number and the Reynolds number. All three can be regarded as giving the ratio of advective to diffusive effects for a particular physical field, and have a similar form of a velocity times a length divided by a diffusivity. The magnetic Reynolds number is related to the magnetic field in an MHD flow, while the Reynolds number is related to the fluid velocity itself, and the Péclet number is related to heat. The dimensionless groups arise in the non-dimensionalization of the respective governing equations, the induction equation, the momentum equation, and the heat equation.
|
|
In stellar astrophysics, Ledoux's name is now associated with the criterion under which material in a star becomes unstable to convection in the presence of a gradient of chemical composition. In homogenous material, the Schwarzschild criterion shows that material is unstable to convection if the radiation field alone would establish a steeper temperature gradient steeper than the adiabatic (or isentropic) temperature gradient. However, Ledoux showed that a composition gradient stabilises or destabilises the material against convection. In convectively-stable regions destabilised by the composition gradient, one expects thermohaline mixing; in convectively- unstable regions that are stabilised, one expects double-diffusive mixing, known in stellar astrophysics as semiconvection.
|
|
Computer simulation of DLA is one of the primary means of studying this model. Several methods are available to accomplish this. Simulations can be done on a lattice of any desired geometry of embedding dimension (this has been done in up to 8 dimensions) or the simulation can be done more along the lines of a standard molecular dynamics simulation where a particle is allowed to freely random walk until it gets within a certain critical range whereupon it is pulled onto the cluster. Of critical importance is that the number of particles undergoing Brownian motion in the system is kept very low so that only the diffusive nature of the system is present.
|
|
His monument in the Church of St Peter and St Paul, Belton, comprising half statues of himself and his wife finely carved in white marble, is inscribed as follows: :He dyed 24th Nov 1679 aet(atis) 89. Shee dyed 27th Jun 1676 aet(atis) 70. M(emoriae) S(acrum) Neer the dust of his deare Father Richard Brownlow Esquire: his Eldest Son Sir John Brownlow Baronet doth deposit his own. Who for his Sincere Piety towards God; Diffusive Charity to the Poor, Conjugall affection to his Lady; Love and Liberality to his neer Relations; With his Prudent Improvement of his Paternall Patrimony; May be a fair pattern to this and After Ages to follow.
|
|
Biological tissues are diffusive media, which means that light attenuation during propagation is due not only to absorption, but also to scattering. The former is related to the chemical composition of the medium and induces photon annihilation, whereas the latter depends on the microscopic inhomogeneities of its refractive index and determines deviations in photon's trajectory. The absorption coefficient \mu_a represents the probability per unit length that an absorption event takes place, while the scattering coefficient \mu_s denotes the probability per unit length that a scattering event occurs. However, many studies refer to the reduced scattering coefficient \mu_s^'=\mu_s (1-g) rather than the simple scattering coefficient, in order to take into account the medium's anisotropy.
|
|
In the context of fish skin pigmentation, the associated equation is a three field reaction–diffusion where the linear parameters are associated with pigmentation cell concentration and the diffusion parameters are not the same for all fields. In dye-doped liquid crystals, photoisomerization process in the liquid crystal matrix is described as a reaction–diffusion equation of two fields (liquid crystal order parameter and concentration of cis-isomer of the azo-dye). Both systems have very different physical mechanisms on the chemical reactions and diffusive process, but on a phenomenological level, both have the same ingredients. Turing-like patterns have also been demonstrated to arise in developing organisms without the classical requirement of diffusible morphogens.
|
|
Since the 6th conference 2015 in Dresden the conference series with the accompanying Diffusion-Fundamentals-Online-Journal has been under the auspices of the Saxon Academy of Sciences and Humanities in Leipzig. The Dresden conference gave rise to the edition of a book on "Diffusive Spreading in Nature, Technology and Society", for which he, together with Armin Bunde, Jürgen Caro and Gero Vogl, was awarded the Literature Prize of the Fonds der Chemischen Industrie in 2019. In 2005, Kärger was awarded the Theodor Litt Prize of the University of Leipzig for his merits in teaching. His Sunday lectures at the Faculty of Physics and Earth Sciences with up to 500 listeners had a special impact on the media.
|
|
Additionally, it measures the density-density correlation (or intermediate scattering function) F(Q,t) as a function of momentum transfer Q and time. Other neutron scattering techniques measure the dynamic structure factor S(Q,ω), which can be converted to F(Q,t) by a Fourier transform, which may be difficult in practice. For weak inelastic features S(Q,ω) is better suited, however, for (slow) relaxations the natural representation is given by F(Q,t). Because of its extraordinary high effective energy resolution compared to other neutron scattering techniques, NSE is an ideal method to observe overdamped internal dynamic modes (relaxations) and other diffusive processes in materials such as a polymer blends, alkane chains, or microemulsions.
|
|
In the Knudsen diffusion regime, the molecules do not interact with one another, so that they move in straight lines between points on the pore channel surface. Self-diffusivity is a measure of the translational mobility of individual molecules. Under conditions of thermodynamic equilibrium, a molecule is tagged and its trajectory followed over a long time. If the motion is diffusive, and in a medium without long-range correlations, the squared displacement of the molecule from its original position will eventually grow linearly with time (Einstein’s equation). To reduce statistical errors in simulations, the self-diffusivity, D_{S}, of a species is defined from ensemble averaging Einstein’s equation over a large enough number of molecules N.
|
|
The entropy of mixing is entirely accounted for by the diffusive expansion of each material into a final volume not initially accessible to it. In the general case of mixing non-ideal materials, however, the total final common volume may be different from the sum of the separate initial volumes, and there may occur transfer of work or heat, to or from the surroundings; also there may be a departure of the entropy of mixing from that of the corresponding ideal case. That departure is the main reason for interest in entropy of mixing. These energy and entropy variables and their temperature dependences provide valuable information about the properties of the materials.
|
|
The central section or upper sections of many large ultramafic intrusions are poorly layered, massive gabbro. This is because as the magma differentiates it reaches a composition favouring crystallisation of only two or three minerals; the magma may also have cooled by this stage sufficiently for the increasing viscosity of the magma to halt effective convection, or convection may stop or break up into inefficient small cells because the revervoir becomes too thin and flat. Crystals accumulation and layering can expel interstitial melt that migrates through the cumulate pile, reacting with it.Irvine TN (1980) "Magmatic infiltration metasomatism, double-diffusive fractional crystallization, and adcumulus growth in the Muskox intrusion and other layered intrusions", pp.
|
|
According to Holman, it exists in around a 100 manuscripts and printings across Europe including England, Scotland, The Netherlands, France, Germany, Austria, Denmark, Sweden, and Italy, in different arrangements for ensemble and solo. The "Lachrimae" tend to be much more abstract than later music (such as Bach and Chopin) and there is no "definitive" version of the piece. Dowland and his contemporaries supposedly played their own versions in a semi-improvised fashion, like jazz musicians today.. Holman argues that the popularity of "Lachrimae" came from its rich melodic and motivic nature. Other English composers in the period generally gave only one or two ideas per strain and padded them out with dull, diffusive contrapuntal writing.
|
|
It was believed that air entered the tracheae through the spiracles, and diffused through the tracheal system to the tracheoles, whereupon O2 was delivered to the cells. However, even at rest, insects show a wide variety of gas exchange patterns, ranging from largely diffusive continuous ventilation, to cyclic respiration, of which discontinuous gas exchange cycles are the most striking. Discontinuous gas exchange cycles have been described in over 50 insect species, most of which are large beetles (order Coleoptera) or butterflies or moths (order Lepidoptera). As the cycles have evolved more than once within the insects, discontinuous gas exchange cycles are likely adaptive, but the mechanisms and significance of their evolution are currently under debate.
|
|
The microgravity environment of the International Space Station is of special importance to this project because only there are all gravity-induced convections eliminated and well-defined conditions for solidification prevail that can be disturbed by artificial fluid flow being under full control of the experimenters. Design solutions that make it possible to improve casting processes and especially aluminium alloys with well-defined properties will be provided. MICAST studies the influence of pure diffusive and convective conditions on aluminium-silicon (AlSi) and aluminium-silicon-iron (AlSiFe) cast alloys on the microstructure evolution during directional solidification with and without rotating magnetic field. The major objective of CETSOL is to improve and validate the modelling of Columnar-Equiaxed Transition (CET) and of the grain microstructure in solidification processing.
|
|
Illustration of a random walk on the top of a special multilayer system, i.e. a multiplex network Diffusion processes are widely used in physics to explore physical systems, as well as in other disciplines as social sciences, neuroscience, urban and international transportation or finance. Recently, simple and more complex diffusive processes have been generalized to multilayer networks. One result common to many studies is that diffusion in multiplex networks, a special type of multilayer system, exhibits two regimes: 1) the weight of inter-layer links, connecting layers each other, is not high enough and the multiplex system behaves like two (or more) uncoupled networks; 2) the weight of inter-layer links is high enough that layers are coupled each other, raising unexpected physical phenomena.
|
|
This method is an approximation of the Richards' (1931) partial differential equation that de-emphasizes soil water diffusion. This was established by comparing the solution of the advection-like term of the Soil Moisture Velocity Equation and comparing against exact analytical solutions of infiltration using special forms of the soil constitutive relations. Results showed that this approximation does not affect the calculated infiltration flux because the diffusive flux is small and that the finite water-content vadose zone flow method is a valid solution of the equation is a set of three ordinary differential equations, is guaranteed to converge and to conserve mass. It requires the assumptions that the flow occurs in the vertical direction only (1-dimensional), and that that soil is uniform within layers.
|
|
Timbered cottage in Jablonec nad Jizerou An already medieval built-up area, which is probably to be found in the vicinity of the St. Procopius Church (originally wooden, from bricks since 1777 thanks to the support of Ernst Adalbert von Harrach) had more diffusive character, also the area from the second half of the 18th century was almost out of order on the slope of the valley. The only organizational factors were contour lines and parcels of land, a completely non-agricultural dwelling were chaotically centered on the link between the church and the mill. Thanks to the large reconstruction of the market town connected with the construction of the railway (1899) and the textile factories along the Jizera, Jablonec nad Jizerou gained the character of a modern mountainous town.
|
|
Gribov V., The Theory of Complex Angular Momentum, 1969 In quantum field theory, Gribov was instrumental in understanding how Regge behavior emerges from field theories which are described by point-particles. He developed the parton model with a different focus than Richard Feynman, using partons to give a qualitative description of the pomeron as a diffusive process. close collaborators went on to formulate a perturbative description of the closely related hard pomeron within QCD. Gribov was the first to note that covariant gauge fixing in a non-abelian gauge theory leaves a large amount of gauge freedom unfixed, which separates the Gauge field phase space into oddly shaped regions called Gribov copies which have the property that it is difficult to stay in any one copy while randomly walking around field space.
|
|
These particles are extremely rare; between 2004 and 2007, the initial runs of the Pierre Auger Observatory (PAO) detected 27 events with estimated arrival energies above , that is, about one such event every four weeks in the 3000 km2 area surveyed by the observatory. There is evidence that these highest- energy cosmic rays might be iron nuclei, rather than the protons that make up most cosmic rays. The postulated (hypothetical) sources of EECR are known as Zevatrons, named in analogy to Lawrence Berkeley National Laboratory's Bevatron and Fermilab's Tevatron, and therefore capable of accelerating particles to 1 ZeV (1021 eV, zetta-electronvolt). In 2004 there was a consideration of the possibility of galactic jets acting as Zevatrons, due to diffusive acceleration of particles caused by shock waves inside the jets.
|
|
It has been shown that in some cases phonon- boundary scattering effects dominate the thermal conduction processes, reducing thermal conductivity. Depending on the nanostructure size, the phonon mean free path values (Λ) may be comparable or larger than the object size, L. When L is larger than the phonon mean free path, Umklapp scattering process limits thermal conductivity (regime of diffusive thermal conductivity). When L is comparable to or smaller than the mean free path (which is of the order 1 µm for carbon nanostructures ), the continuous energy model used for bulk materials no longer applies and nonlocal and nonequilibrium aspects to heat transfer also need to be considered. In this case phonons in defectless structure could propagate without scattering and thermal conductivity becomes ballistic (similar to ballistic conductivity).
|
|
The analysis assumes that the flow is an incompressible flow, and that the perturbations are governed by the linearized Euler equations and, thus, are inviscid. With these considerations, the main result of this analysis is that, if the density of the burnt gases is less than that of the reactants, which is the case in practice due to the thermal expansion of the gas produced by the combustion process, the flame front is unstable to perturbations of any wavelength. Another result is that the rate of growth of the perturbations is inversely proportional to their wavelength; thus small flame wrinkles (but larger than the characteristic flame thickness) grow faster than larger ones. In practice, however, diffusive and buoyancy effects that are not taken into account by the analysis of Darrieus and Landau may have a stabilizing effect.
|
|
Oak Ridge National Laboratory - New Oak Ridge company putting hybrid solar lighting on map Sunlight Direct- Architectural Design Information However, this system was taken off the market in 2009. In view of the usually small diameter of the fibers, an efficient daylighting set-up requires a parabolic collector to track the sun and concentrate its light. Optical fibers intended for light transport need to propagate as much light as possible within the core; in contrast, optical fibers intended for light distribution are designed to let part of the light leak through their cladding.Use Of Diffusive Optical Fibers For Plant Lighting Optical fibers are also used in the Bjork system sold by Parans Solar Lighting AB.Parans Bjork Parans Bjork system review by Inhabitat The optic fibers in this system are made of PMMA (PolyMethylMethAcrylate) and sheathed with Megolon, a halogen-free thermoplastic resin.
|
|
Neutrons are uncharged constituents of atoms and penetrate materials well, deflecting only from the nuclei of atoms. The statistical accumulation of deflected neutrons at different positions beyond the sample can be used to find the structure of a material, and the loss or gain of energy by neutrons can reveal the dynamic behaviour of parts of a sample, for example diffusive processes in solids. At ISIS the neutrons are created by accelerating 'bunches' of protons in a synchrotron, then colliding these with a heavy tungsten metal target, under a constant cooling load to dissipate the heat from the 160 kW proton beam. The impacts cause neutrons to spall off the tungsten atoms, and the neutrons are channelled through guides, or beamlines, to around 20 instruments, each individually optimised for the study of different types of interactions between the neutron beam and matter.
|
|
Convective heat transfer is one of the major types of heat transfer, and convection is also a major mode of mass transfer in fluids. Convective heat and mass transfer takes place both by diffusion – the random Brownian motion of individual particles in the fluid – and by advection, in which matter or heat is transported by the larger-scale motion of currents in the fluid. In the context of heat and mass transfer, the term "convection" is used to refer to the combined effects of advective and diffusive transfer. See Table 1.5 Sometimes the term "convection" is used to refer specifically to "free heat convection" (natural heat convection) where bulk-flow in a fluid is due to temperature-induced differences in buoyancy, as opposed to "forced heat convection" where forces other than buoyancy (such as pump or fan) move the fluid.
|
|
However quantum mechanics tells us that to find the total probability we have to sum up the quantum-mechanical amplitudes of the paths rather than the probabilities themselves. Therefore, the correct (quantum-mechanical) formula for the probability for an electron to move from a point A to a point B includes the classical part (individual probabilities of diffusive paths) and a number of interference terms (products of the amplitudes corresponding to different paths). These interference terms effectively make it more likely that a carrier will "wander around in a circle" than it would otherwise, which leads to an increase in the net resistivity. The usual formula for the conductivity of a metal (the so-called Drude formula) corresponds to the former classical terms, while the weak localization correction corresponds to the latter quantum interference terms averaged over disorder realizations.
|
|
Interconnected 3 compartment models, as used in the Goldman models In contrast to the independent parallel compartments of the Haldanean models, in which all compartments are considered risk bearing, the Goldman model posits a relatively well perfused "active" or "risk-bearing" compartment in series with adjacent relatively poorly perfused "reservoir" or "buffer" compartments, which are not considered potential sites for bubble formation, but affect the probability of bubble formation in the active compartment by diffusive inert gas exchange with the active compartment. During compression, gas diffuses into the active compartment and through it into the buffer compartments, increasing the total amount of dissolved gas passing through the active compartment. During decompression, this buffered gas must pass through the active compartment again before it can be eliminated. If the gas loading of the buffer compartments is small, the added gas diffusion through the active compartment is slow.
|
|
The work by his group led to the development of the concept and elucidation of the properties of ballistic, snake, and diffusive photons based on the time of flight of photons within the media. He introduced the terms ballistic and snake photons, and identified these photons as carriers of information for direct shadowgram imaging. Comprehending of the characteristics of these photons led to the development of various gating techniques for sorting out image-bearing photons for direct two-dimensional imaging of inhomogeneities in turbid media in general, and biomedical samples in particular. In addition to his technical contributions, Alfano has encouraged the growth of the field by organizing topical meetings and conferences for OSA and SPIE, and later co- chairing many optical imaging conferences with Britton Chance, whereby he introduced young scientists and engineers to biomedical optics, and attracted other researchers to the field.
|
|
Thomas Graham is known for his studies on the behaviour of gases, which resulted in his formulation of two relationships, both since becoming known as "Graham's Laws," the first regarding gas diffusion, and the second regarding gas effusion. In the former case, Graham deduced that when measured repeatedly under the same conditions of pressure and temperature, the rate of diffusive mixing of a gas is inversely proportional to the square root of its density, and given the relationship between density and molar mass, also inversely proportional to the square root of its molar mass. In the same way, in the latter case, regarding effusion of a gas through a pin hole in to a vacuum, Graham deduced that the rate of effusion of a gas is inversely proportional to the square root of its molar mass. These two are sometimes referred to as a combined law (describing both phenomena).
|
|
Two quite different types of fluid motion exist—and therefore are classified accordingly—depending on whether the stable stratification is provided by the density-affecting component with the lowest or the highest molecular diffusivity. If the stratification is provided by the component with the lower molecular diffusivity (for example in case of a stable salt-stratified ocean perturbed by a thermal gradient due to an iceberg—a density ratio between 0 and 1), the stratification is called to be of "diffusive" type (see external link below), otherwise it is of "finger" type, occurring frequently in oceanographic studies as salt-fingers. These long fingers of rising and sinking water occur when hot saline water lies over cold fresh water of a higher density. A perturbation to the surface of hot salty water results in an element of hot salty water surrounded by cold fresh water.
|
|
These expansions are performed both in the interfacial region (inner expansion) and in the bulk (outer expansion), and then are asymptotically matched order by order. The result gives a partial differential equation for the diffusive field and a series of boundary conditions at the interface, which should correspond to the sharp interface model and whose comparison with it provides the values of the parameters of the phase-field model. Whereas such expansions were in early phase-field models performed up to the lower order in \varepsilon only, more recent models use higher order asymptotics (thin interface limits) in order to cancel undesired spurious effects or to include new physics in the model. For example, this technique has permitted to cancel kinetic effects, to treat cases with unequal diffusivities in the phases, to model viscous fingering and two-phase Navier–Stokes flows, to include fluctuations in the model, etc.
|
|
Since moving to Trondheim in 1977, Naqvi has worked on a wide range of problems within physics, chemistry and biology, dividing his time equally between theory and experiment and between the pure and the applied. These topics include: (1) calculation of Franck–Condon factors, (2) applications of linear transport theory to chemical kinetics, diffuse reflection spectroscopy, and phonon transport in semiconductors, (3) spectroscopy of absorbing and scattering specimens, (4) primary photophysical processes in carotenoids, vitamin E and related molecules, (5) revival of quantum wave packets, (6) photoprotection in artificial and natural photosynthesis, (7) use of diffusive gradient in thin films (DGTF) for the in situ measurement of the labile forms of chemical elements in aqueous environments, sediments and soils, and (8) non-invasive measurement of blood pressure. Naqvi’s many coauthors include a very large number of scientists from all over the world. Within NTNU, his collaborators include, apart from many physicists, several chemists (analytical, organic, physical) and two mathematicians.
|
|
The number which the > nature and extent of his business require, in addition to the many drawn > from the line to fill the different offices of the staff, when it is > considered, that they ought all to be men of abilities, may seem too large a > draft upon the line. But a consideration still more forcible is, that in a > service so complex as ours, it would be wrong and detrimental to restrict > the choice; the vast diversity of objects, occurrences and correspondencies, > unknown in one more regular and less diffusive; constantly calling for > talents and abilities of the first rate, men who possess them, ought to be > taken, wherever they can be found. On the battlefield, the aides-de-camp were couriers--delivering Washington's orders on horseback and gathering or relaying intelligence on enemy troop movement. Samuel Blachley Webb was wounded at the October 28, 1776, Battle of White Plains and at the December 26, 1776, Battle of Trenton.
|
|
A Shock-Induced Combustion Ramjet Engine (abbreviated as Shcramjet; also called Oblique Detonation Wave Engine (ODWE), or simply referred to as Shock- Ramjet Engine) is a concept of air-breathing ramjet engine, proposed to be used for hypersonic, as well as, single-stage-to-orbit (SSTO) propulsion applications. From the overall design point of view, the shcramjet engine is similar to a scramjet engine; however, unlike the diffusive mode of combustion in scramjet engine, a shcramjet engine combustion takes place across a very thin region of standing oblique shock and/or detonation waves stabilized over a wedge, blunt body etc. Since combustion in a shcramjet engine is confined to very short region across the igniting wave, the combustor length in a shcramjet can be significantly shorter than the scramjet that requires a lengthy combustor for complete fuel-air mixing and combustion. Also, the shcramjet is believed to have a better overall propulsive performance than the scramjet at higher Mach numbers, especially above Mach 12.
|
|
China is home to many of the world's tallest religious statues, including the tallest of all, the Spring Temple Buddha in Henan. Clear data on religious affiliation in China is difficult to gather due to varying definitions of "religion" and the unorganized, diffusive nature of Chinese religious traditions. Scholars note that in China there is no clear boundary between three teachings religions and local folk religious practice. A 2015 poll conducted by Gallup International found that 61% of Chinese people self-identified as "convinced atheist", though it is worthwhile to note that Chinese religions or some of their strands are definable as non- theistic and humanistic religions, since they do not believe that divine creativity is completely transcendent, but it is inherent in the world and in particular in the human being. According to a 2014 study, approximately 74% are either non-religious or practise Chinese folk belief, 16% are Buddhists, 2% are Christians, 1% are Muslims, and 8% adhere to other religions including Taoists and folk salvationism.
|
|
The atmosphere includes a representation of radiative fluxes, mixing in the atmospheric boundary layer, representations of the impacts of stratus and cumulus clouds, a scheme for representing drag on upper level winds caused by gravity waves, changes in the spatial distribution of ozone and the ability to represent the impact of multiple greenhouse gases. Ocean The ocean component is a 50-level ocean, run at a resolution of 1° in the east–west direction and varying in the north-south direction from 1 degree in the polar regions to 1/3 of a degree along the equator. This resolution is sufficient to resolve the equatorial current system, but is too coarse to capture the highly energetic mesoscale eddies- whose advective and diffusive effects are parameterized. Other key parameterizations include a free surface height that changes in response to evaporation, precipitation, and convergence of ocean currents, absorption of sunlight tied to observed chlorophyll concentrations, a representation of the oceanic mixed layer, inclusion of turbulence generated by tidal mixing on shelves and schemes allowing water from marginal seas such as the Red and Baltic Seas to "mix" across narrow straits at their mouths.
|
|