Anoxia, as this physiological process is called, also sets in after death.
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The second child died of complications of anoxia, or lack of oxygen to the brain.
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In the case of the Cambrian it was periods of anoxia of as-yet-unknown cause.
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The custom-designed device mimicked natural organ systems inside the body, pumping a protective solution designed to promote recovery from prolonged anoxia.
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For example, if an object is made of an ether-based polyurethane, it's more susceptible to oxygen, and should be stored in anoxia.
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When the 86 sculptures arrived at destination, they were promptly put inside a gigantic "anoxia chamber" large enough to contain the four crates that housed them.
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The brains were removed from the skulls and hooked up to the BrainEx device four hours after death (so these brains experienced four hours of anoxia).
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The brains were hooked up to the system, known as BrainEx, four hours after death was declared and after severe oxygen starvation, or anoxia, had set in.
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The anoxia chamber is incredibly thorough—no matter where they're hiding, bugs can't get away from a lack of oxygen—and it's safe enough for wooden objects, which can be prone to contraction or expansion if treated with freezing temperatures or heat.
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Red-hot ordnance falls out of a clear blue sky; the thin platform of lava gives way; majestic seas become the drowning wave; the beautiful stillness of the storm becomes the shredding motion of the tornado; the exhilaration of altitude crosses into anoxia.
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While nobody is sure exactly how bad this will get, history doesn't bode well: Research published last year suggests that global warming-fueled ocean anoxia might have been the chief culprit in the worst mass extinction event life on Earth ever experienced.
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" After synthesizing a vast body of literature and reviewing almost 20 global mass extinctions over the past half billion years — including the most extreme ones, the so-called Big Five — the authors concluded that "large scale volcanism is the main driver of mass extinctions" and that "most extinctions are associated with global warming and proximal killers such as marine anoxia.
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Once anoxia became established, it would have been sustained by a positive feedback loop because deep water anoxia tends to increase the recycling efficiency of phosphate, leading to even higher productivity.
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The lack of oxygen (anoxia) kills bottom-living organisms and creates dead zones.
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In plants it regulates water intake/export in response to water availability and cytoplasmic pH during anoxia.
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This caused a temporary state of total anoxia in the fjord, and resulted in dramatic fish mortality.
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Adults of Cicindela togata are unable to survive immersion in water, but larvae are able to survive a prolonged period, up to 6 days, of anoxia during floods. Anoxia tolerance in the larvae may have been sustained by switching to anaerobic metabolic pathways or by reducing metabolic rate. Anoxia tolerance in the adult carabid beetle Pelophilia borealis was tested in laboratory conditions and it was found that they could survive a continuous period of up to 127 days in an atmosphere of 99.9% nitrogen at 0 °C.
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DXV was first isolated and named in 1978. DXV was discovered as a contaminant in adult D. melanogaster while studying rhabdoviruses. Assay results of DXV showed that DXV induces sensitivity to both carbon dioxide and NH2, which suggests general anoxia. Therefore, the pathogenic pathway for DXV leads to anoxia sensitivity and death of D. melanogaster.
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Black shale is one of the preliminary indicators of anoxia and perhaps euxinia Black shales are organic rich, microlaminated sedimentary rocks often associated with bottom water anoxia. This is because anoxia slows the degradation of organic matter, allowing for greater burial in the sediments. Other evidence for anoxic burial of black shale includes the lack of bioturbation, meaning that there were no organisms burrowing into the sediment because there was no oxygen for respiration. There must also be a source of organic matter for burial, generally from production near the oxic surface.
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Despite the anoxia indicated by the BIF, photosynthesis continued, stabilizing climates at new levels during the second part of the Proterozoic Era.
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Another anoxia-tolerant animal that is commonly used as a model to study anoxia in the mammalian brain is the crucian carp, which can survive at even more extreme anoxic conditions than the painted turtle can. Unlike C. picta, which takes such drastic measures in becoming comatose to maintain an optimum ATP concentration, the crucian carp does not become comatose in anoxia. Instead, it stays active by maintaining its normal cardial output as well as increasing its cerebral blood flow. Even though glycolysis is stimulated early in anoxia in both the crucian carp and C. picta, the crucian carp is able to stay active because of its capability to re-route the glycolytic pathway such that lactate is converted into ethanol, which can then be released into the water via the gills, thus preventing lactate overload and acidosis.
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The concentration of ferritin has been shown to increase in response to stresses such as anoxia; this implies that it is an acute phase protein.
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A section of mouse liver showing several apoptotic cells, indicated by arrows stained to show cells undergoing apoptosis (orange) Neonatal cardiomyocytes ultrastructure after anoxia-reoxygenation.
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All cells require ATP as an energy source for their metabolic activity. The kidney is damaged by anoxia when kidney cortical cells are unable to generate sufficient ATP under anaerobic conditions to meet the needs of the cells. When excising a kidney some anoxia is inevitable in the interval between dividing the renal artery and cooling the kidney. It has been shown by Bergstrom that 50% of a dog's kidney's cortical cells ATP content is lost within 1 minute of clamping the renal artery, and similar results were found by Warnick in whole mice kidneys, with a fall in cellular ATP by 50% after about 30 seconds of warm anoxia.
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Evidence for widespread ocean anoxia (severe deficiency of oxygen) and euxinia (presence of hydrogen sulfide) is found from the Late Permian to the Early Triassic. Throughout most of the Tethys and Panthalassic Oceans, evidence for anoxia, including fine laminations in sediments, small pyrite framboids, high uranium/thorium ratios, and biomarkers for green sulfur bacteria, appear at the extinction event. However, in some sites, including Meishan, China, and eastern Greenland, evidence for anoxia precedes the extinction. Biomarkers for green sulfur bacteria, such as isorenieratane, the diagenetic product of isorenieratene, are widely used as indicators of photic zone euxinia because green sulfur bacteria require both sunlight and hydrogen sulfide to survive.
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Bacteria, dissolved organics and oxygens consumption in salinity stratified Chesapeake Bay, an anoxia paradigm. Am. Zool. 37, 612-620.Officer, C.B., Smayda, T.J. and Mann, R., 1982.
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Their abundance in sediments from the P-T boundary indicates hydrogen sulfide was present even in shallow waters. This spread of toxic, oxygen-depleted water would have devastated marine life, causing widespread die-offs. Models of ocean chemistry suggest that anoxia and euxinia were closely associated with hypercapnia (high levels of carbon dioxide). This suggests that poisoning from hydrogen sulfide, anoxia, and hypercapnia acted together as a killing mechanism.
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If continental shelves are exposed by falling sea levels, then organic surface runoff flows into deeper oceanic basins. The organic matter would have more time to leach out phosphate and other nutrients before being deposited on the seabed. Increased phosphate concentration in the seawater would lead to eutrophication and then anoxia. Deep-water anoxia and euxinia would impact deep-water benthic fauna, as expected for the first pulse of extinction.
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More recently, in May 2020, a study suggested the first pulse of mass extinction was caused by volcanism which induced global warming and anoxia, rather than cooling and glaciation.
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Due to Prajmaline's sodium channel-blocking properties, it has been shown to protect rat white matter from anoxia (82 +/- 15%). The concentration used causes little suppression of the preanoxic response.
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In patients surviving traumatic brain injury, the occurrence of these episodes is one in every three. PSH can also be associated with severe anoxia, subarachnoid and intracerebral hemorrhage, and hydrocephalus.
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D 274:2481-2484. This mechanism is strictly regulated by conditions of partial anoxia in the soil, at a depth determined by whether the texture is sandy or clayey. Wood colonization inside the taproot spreads up to the collar and to other portions of the root system. A controlled and effective method for artificially infecting young Hevea plants has been developed by reproducing the conditions of soil anoxia in the greenhouse.Nandris, D.; Nicole, M. and Geiger, J. P. (1983).
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Another heavily-discussed factor in the Late Ordovician mass extinction is anoxia, the absence of dissolved oxygen in seawater. Anoxia not only deprives most life forms of a vital component of respiration, it also encourages the formation of toxic metal ions and other compounds. One of the most common of these poisonous chemicals is hydrogen sulfide, a biological waste product and major component of the sulfur cycle. Oxygen depletion when combined with high levels of sulfide is called euxinia.
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Modelers have hypothesized that due to environmental conditions anoxia and sulfide may have been brought up from a deep, vast euxinic reservoir in upwelling areas, but stable, gyre-like areas remained oxic.
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Hypercapnia best explains the selectivity of the extinction, but anoxia and euxinia probably contributed to the high mortality of the event. The persistence of anoxia through the Early Triassic may explain the slow recovery of marine life after the extinction. Models also show that anoxic events can cause catastrophic hydrogen sulfide emissions into the atmosphere (see below). The sequence of events leading to anoxic oceans may have been triggered by carbon dioxide emissions from the eruption of the Siberian Traps.
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Journal für Psychologie und Neurologie; Bd. 28. Joh.- Ambr.- Barth- Verlag. Leipzig. (German). Professor of neurology Terence Hines (2003) claimed that near-death experiences are hallucinations caused by cerebral anoxia, drugs, or brain damage.
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The resulting eutrophication and algae blooms result in anoxia and dead zones. As a consequence, as nitrate forms a component of total dissolved solids, they are widely used as an indicator of water quality.
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The consumption of this newly abundant organic life by aerobic bacteria would produce anoxia and mass extinction. The resulting elevated levels of carbon burial would account for the black shale deposition in the ocean basins.
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Pests may be treated with a number of methods, including freezing, insecticide, or anoxia. These treatments help kill off adults and larvae, though specimens may require additional cleaning and stabilization after these treatments are performed.
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Some species of billfish, predatory pelagic predators such as sailfish and marlin, that have undergone habitat compression actually have increased growth since their prey, smaller pelagic fish, experienced the same habitat compression, resulting in increased prey vulnerability to billfishes. Fish with tolerance to anoxic conditions, such as jumbo squid and lanternfish, can remain active in anoxic environments at a reduced level, which can improve their survival by increasing avoidance of anoxia intolerant predators and have increased access to resources that their anoxia intolerant competitors cannot.
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Nizofenone (Ekonal, Midafenone) is a neuroprotective drug which protects neurons from death following cerebral anoxia (interruption of oxygen supply to the brain). It might thus be useful in the treatment of acute neurological conditions such as stroke.
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An in vivo study in rats showed that oral administration of vicine resulted in only small reductions in glutathione concentrations and no mortality. Intraperitoneal administration however, led to a rapid decrease in glutathione followed by death because of anoxia.
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The hypolimnion can be anoxic for up to half the year. Anoxia is more common in the hypolimnion during the summer when mixing does not occur. In the absence of oxygen from the epilimnion, decomposition can cause hypoxia in the hypolimnion.
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Cerebral hypoxia is a form of hypoxia (reduced supply of oxygen), specifically involving the brain; when the brain is completely deprived of oxygen, it is called cerebral anoxia. There are four categories of cerebral hypoxia; they are, in order of severity: diffuse cerebral hypoxia (DCH), focal cerebral ischemia, cerebral infarction, and global cerebral ischemia. Prolonged hypoxia induces neuronal cell death via apoptosis, resulting in a hypoxic brain injury. Cases of total oxygen deprivation are termed "anoxia", which can be hypoxic in origin (reduced oxygen availability) or ischemic in origin (oxygen deprivation due to a disruption in blood flow).
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The navigator bailed the gunner out of the aircraft in a successful effort to save his life. Unknown to Morgan, the waist, tail and radio gunners became unconscious from lack of oxygen and were threatened with death by anoxia. Morgan, unable to call for assistance because of the damaged interphone, had to decide whether to turn back immediately or try to fly all the way to the target and back within the protection of the formation. He also had to decide whether or not to subject Campbell to anoxia by cutting off his oxygen to disable him.
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This period is reflected in the geological record by an increase in black shale deposition, representing global anoxia. This may be related to global changes in oceanic circulation and may have been the worst marine anoxic event of the last 550 million years.
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Non- traumatic injuries could include those caused by illnesses, such as tumours, encephalitis, meningitis and sinusitis. They could also be caused by infections such as septicaemia; events such as anoxia and hypoxia occasioned by strangulation or near drowning, lead toxicity, and substance misuse.
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In parts of the oceans, especially the north Atlantic Ocean, bioturbation was absent. This may be due to bottom-water anoxia, or by changing ocean circulation patterns changing the temperatures of the bottom water. However, many ocean basins remained bioturbated through the PETM.
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Around 60 tons of dead fish washed up in a lagoon in Rio de Janeiro beginning in January, possibly as a result of local ocean anoxia caused by algal blooms triggered by increased eutrophication from the excess run-off produced by the flooding.
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Ovchinnikov LP, Motuz LP, Natapov PG, Averbuch LJ, Wettenhall RE, Szyszka R, Kramer G, Hardesty B. 1990. Three phosphorylation sites in elongation factor 2. FEBS Lett. 275: 209– 212 Cellular stressors, such as anoxia have proven to induce translational inhibition through this biochemical interaction.
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Neurons are more susceptible to brain ischemia than the supporting glial cells, because neurons have higher energy demand, conduct an action potential, and produce glutamate, whereas glial cells lack those properties. Yet neurons differ among themselves in their sensitivity to ischemia, depending on the specific properties they exhibit, relating to their locations in the brain. Selective vulnerability is how some parts of the brain are more sensitive to anoxia than others, and thus to ischemic insult. Anoxia-prone cells in the brain include the hippocampal pyramidal cells of CA1, cerebellar purkinje cells, pyramidal neocortical neurons in some layers, basal ganglia, reticular neurons of the thalamus, and brainstem neurons.
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Drowning can be considered as going through four stages: # Breath-hold under voluntary control until the urge to breathe due to hypercapnia becomes overwhelming # Fluid is swallowed and/or aspirated into the airways # Cerebral anoxia stops breathing and aspiration # Cerebral injury due to anoxia becomes irreversible Generally, in the early stages of drowning a person holds their breath to prevent water from entering their lungs. When this is no longer possible a small amount of water entering the trachea causes a muscular spasm that seals the airway and prevents further passage of water. If the process is not interrupted, loss of consciousness due to hypoxia is followed rapidly by cardiac arrest.
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Much of his career was spent at the Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology before joining Cal Poly in 1988.Altenbach, A. V., In Bernhard, J. M., & In Seckbach, J. (2012). Anoxia: Evidence for eukaryote survival and paleontological strategies. Dordrecht: Kluwer Academic Publishers.
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Shirl Jennings (1940–2003) was blinded by illness as a young boy. Experimental surgery in 1991 partially restored his vision, but like Bradford and May, Jennings found the transition to sightedness difficult. In 1992, a pneumonia infection resulted in anoxia, and ultimately cost Jennings his vision again.
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In situations lacking oxygen (a.k.a., anoxia), many cryptobionts (such as M. tardigradum) take in water and become turgid and immobile, but can survive for prolonged periods of time. Some ectothermic vertebrates and some invertebrates, such as brine shrimps,Clegg et al. 1999 copepods,Marcus et al.
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Many papers discussing ancient euxinic events use the presence of black shale as a preliminary proxy for anoxic bottom waters, but their presence does not in and of itself indicate euxinia or even strong anoxia. Generally geochemical testing is needed to provide better evidence for conditions.
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In, R. Miller (ed.), The Geology of Namibia. Geological Society of Namibia Special Publication, Volume 2, p. 13-229 – 13-272. Schröder, S. and Grotzinger, J. P., 2007, Evidence for anoxia at the Ediacaran-Cambrian boundary: The record of redox-sensitive trace elements and rare-earth elements in Oman.
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Schwark, L., & Frimmel, A. (2004). Chemostratigraphy of the Posidonia Black Shale, SW- Germany: II. Assessment of extent and persistence of photic-zone anoxia using aryl isoprenoid distributions. Chemical Geology, 206(3-4), 231–248.Ghanizadeh, A., Amann-Hildenbrand, A., Gasparik, M., Gensterblum, Y., Krooss, B. M., & Littke, R. (2014).
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He experiences anoxia, resulting in brain damage. Henry survives but can neither move nor talk and he suffers retrograde amnesia. While in a nursing facility, he slowly regains movement and speech with the help of a physical therapist named Bradley. Henry's recovery creates a financial burden for the family.
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The brains of several mammalian neonates have been identified as able to confer resistance to anoxia in a fashion similar to that of the anoxic- tolerant aquatic organisms. This is still a relatively new area of study that could have a clinical significance in combating stroke in humans. A study that looked into anoxic-tolerance in newborn mammals identified two main ways in which they cope with acute hypoxia. While most newborns, preferentially, depress their metabolic rate to conserve energy during anoxia, some mammalian newborns—such as the pig, the deer, and other animals in their class, which are capable of a high degree of independent activity from birth—employ hyperpnoea (abnormally rapid or deep breathing).
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He first explained the Fink Effect in his 1955 paper "Diffusion anoxia". He went to the University of London at 16. He served as a medical officer during World War II in South Africa. He has two daughters (Jean Moore and Susan Myers), two sisters, one brother and five grandchildren.
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Adam, M. E. and J. W. Lewis. 1992. The lack of co-existence between Lymnaea peregra and Lymnaea auricularia (Gastropoda: Pulmonata). Journal of Molluscan Studies 58(2):227-228. It can tolerate polysaprobic waters, or areas of major pollution and anoxia with high concentrations of organic matter, sulfides and bacteria.
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Revised 17 July 2010. Retrieved 17 January 2010. This world perspective on oceanic currents demonstrates the interdependencies of transnational regions on circulating currents. Oceanic anoxic events or anoxic events (anoxia conditions) were intervals in the Earth's past where portions of oceans became depleted in oxygen (O2) over a large geographic areas.
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Because of its anoxia, the Cariaco Basin has also a unique chemistry. Bacteria inhabit both the oxic and anoxic portions of the water column, with a maximum around the interface where oxygen disappears.Taylor, G. T., M. I. Scranton, M. Iabichella, T.-Y. Ho, R. C. Thunell, R. Varela, and F. E. Muller-Karger.
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Numerous fouling control methods have been proposed and tested, either in laboratory conditions only, or in actual operating environments. These include antifouling materials and coatings, manual/mechanical cleaning, filtration, chemical treatments, thermal shock, anoxia and hypoxia, desiccation, ozonation, ultraviolet treatment, electric currents, ultrasound, manipulations of flow speed, biological control, and various miscellaneous methods.
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He dies from anoxia, Lloyd and Stone look on as Pruett's body drifts away into space. With Pruett gone, Stone takes command. A Soviet spacecraft suddenly appears and its cosmonaut tries to make contact. It can do nothing but deliver oxygen, since the Soviet ship is too small to carry additional passengers.
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The physical manifestations of this were elevated atmospheric and oceanic temperatures, a significant sea-level transgression, and a period of widespread anoxia, leading to the extinction of 26% of all genera. These eruptions would also have resulted in the emission of large quantities of carbon dioxide into the atmosphere, leading to global warming. Additionally, the emission of sulfur monoxide, hydrogen sulfide, carbon monoxide, and halogens into the oceans would have made seawater more acidic resulting in the dissolution of carbonate, and further release of . This runaway greenhouse effect was probably put into reverse by the decline of the anomalous volcanic activity and by increased -driven productivity in oceanic surface waters, leading to increased organic carbon burial, black shale deposition, anoxia and mass extinction in the ocean basins.
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Suicide attempts can result in serious and permanent injuries and/or disabilities. 700,000 (or more) Americans survive a suicide attempt each year. People who attempt either hanging or charcoal grill carbon monoxide poisoning and survive can face permanent brain damage due to cerebral anoxia. People who take a drug overdose and survive can face severe organ damage (e.g.
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Excretion of lactate in significant quantities is not a common nor a desirable metabolic facility, but the excretion of ethanol presents no serious metabolic challenges. This metabolic expedient avoids the fatal accumulation of acid end-products of anaerobic glycolysis.Johnston, Ian A. & Bernard, Lynne M. Utilization of the Ethanol Pathway in Carp Following Exposure to Anoxia. J. exp. exp. Biol.
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The mechanisms that damage kidneys during hypothermic storage can be sub-divided as follows: # Injury to the metabolic processes of the cell caused by: ## Cold ## Anoxia when the kidney is warm both before and after the period of hypothermic storage. ## Failure to supply the correct nutrients. ## Toxin accumulation in the perfusate. ## Toxic damage from the storage fluid.
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The central nervous system is often red or pink because it contains hemoglobin. This stores oxygen for peak activity or when the animal experiences anoxia, for example while burrowing in oxygen-free sediments. Some species have paired cerebral organs, sacs whose only openings are to the outside. Others species have unpaired evertible organs on the front of their heads.
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Hartmann published 90 papers during his career. His scientific work pertained to biochemistry and problems of metabolism, while his clinical pediatric interests included anoxia, hypoglycemia, nephritis, nephrosis and chemotherapy. He was among the first doctors to use insulin to treat diabetes in infants. His best known contribution to medicine was in body electrolytes and intravenous fluids replacement.
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Because of decaying milfoil in the lake's two hypolimnia during this era, the lake experienced an intensification of hypolimnetic anoxia. In the early 1990s the aquatic plant covered over 85 acres (over 40%) of the lake. This infestation creates a large oxygen demand in the lake, limiting cold water habitat. Aquatic macrophyte harvesting was initiated in 1980.
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Boulder, CO, Geological Society of America, 2002; pp. 525-9. Evidence points to a warming climate, the spread of anoxia in the oceans, and ocean acidifcation as the probable cause of these marine extinctions, linked in turn to the massive volcanism of the Karoo- Ferrar eruptions that occurred at this time.Marti, Joan, and Gerald Ernst. Volcanoes and the Environment.
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The Francevillian biota disappears and is absent in the overlying black shale. El Albani attributes this to their extinction. The biota formed with the Lomagundi event, a temporary increase in atmospheric oxygen, and became extinct from marine anoxia when the event ended. The biota represents the first known experiment in multicellularity, with no extant multicellular descendants.
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Poulton and his collaborators did research on oesophageal pain, dissociation curves of blood, physiological effects of anoxia, and creatinine excretions in dietary modifications. When Sir Frederick Taylor died in 1920, Poulton became the editor, assisted by C. Putnam Symonds and Harold Wordsworth Barber, for the 12th edition of Taylor's Practice of Medicine (1922) and for three subsequent editions.
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Repinotan is able to suppress caspase-3 through MAPK and PKCalpha. Apoptosis as a result of anoxia/reoxygenation and H(2)O(2) treatment may also be inhibited. Repinotan has been found to bind with high to moderate affinity to the receptors alpha-1 and alpha-2 adrenergic, 5-HT7- and 5-HT1D, dopamine D2 and D4, sigma sites, and 5-HT2C.
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Anoxia can be tolerated longest in the coldest water, even down to 0 °C, because colder conditions lower the metabolic rate. Alcohol production occurs mainly in the muscle tissues, but also in the liver, where the process is thought to have originated. Similarly goldfish can produce alcohol in muscle tissues, but to a much more limited extent.Shoubridge, E. A. & Hochachka, P. W. (1980).
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Ethical questions have been raised regarding the blood collection process due to the potential suffering caused to the fetus. Although anoxia or active slaughter could be used to induce unconsciousness or death prior to serum harvesting, exposure of live unborn calves to oxygen can cause them to gain awareness before being killed, resulting in active debate about the ethics of harvesting serum.
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The array consists of two lines of moorings, one off Newport, Oregon (the Oregon Line) and the other off Grays Harbor, Washington (the Washington Line). Gliders sample between the mooring lines. The array focuses on observing the influence of the Columbia River on the coastal ecosystem. It also samples a prototypical upwelling regime on a narrow continental shelf where anoxia events are common.
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A few studies have proposed that the first extinction pulse did not begin with the Hirnantian glaciation, but instead corresponds to an interglacial period or other warming event. Anoxia would be the most likely mechanism of extinction in a warming event, as evidenced by other extinctions involving warming. However, this view of the first extinction pulse is controversial and not widely accepted.
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The ichnogenus is found both in anaerobic, organic-rich sediments and in oxic layers, where it is almost invariably the last in the bioturbation sequence, i.e., it was placed deep within the sediments, away from oxidizing surficial and interstitial water. These suggest the tracemaker's ability to tolerate oxygen deprivation very well. Therefore, Chondrites can be used as an indicator of anoxia in sediments.
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A near- death experience (NDE) is a personal experience associated with impending death, encompassing multiple possible sensations. Research from neuroscience considers the NDE to be a hallucinatory state caused by various neurological factors such as cerebral anoxia, hypercarbia, abnormal activity in the temporal lobes and brain damage.Olaf Blanke, Sebastian Dieguez. "Leaving Body and Life Behind: Out-of-Body and Near-Death Experience" (2009).
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The painted turtle (Chrysemys picta) uses the mechanism of metabolic depression to combat oxygen depletion. Within a few minutes of anoxia onset in the turtle's brain there is decreased cerebral blood flow that eventually ceases. Meanwhile, glycolysis is stimulated to maintain a near optimum ATP production. This compensatory stimulation of glycolysis occurs because, in the turtle's brain, cytochrome a and a3 have a low affinity for oxygen.
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Other studies linked the lead (Pb) isotopes of OAE-2 to the Caribbean-Colombian and the Madagascar LIPs. A modeling study performed in 2011 confirmed that it is possible that a LIP may have initiated the event, as the model revealed that the peak amount of carbon dioxide degassing from volcanic LIP degassing could have resulted in more than 90 percent global deep-ocean anoxia.
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Non-dominant females are observed copulating more often with lower- ranking males. It is costly for female hyenas to give birth through their long peniform clitoris. The umbilical cord is 12–18 cm long, while the journey from the uterus to the clitoris end is 40 cm. The umbilical cord often breaks before the cub emerges, leading to death by anoxia for many young.
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Nutrient fluxes in the profundal zone are primarily driven by release from the benthos. The anoxic nature of the profundal zone drives ammonia release from benthic sediment. This can drive phytoplankton production, to the point of a phytoplankton bloom, and create toxic conditions for many organisms, particularly at a high pH. Hypolimnetic anoxia can also contribute to buildups of iron, manganese, and sulfide in the profundal zone.
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In many cases, OMZs are permanent or semipermanent areas. Remains of organisms found within sediment layers near the mouth of the Mississippi River indicate four hypoxic events before the advent of synthetic fertilizer. In these sediment layers, anoxia-tolerant species are the most prevalent remains found. The periods indicated by the sediment record correspond to historic records of high river flow recorded by instruments at Vicksburg, Mississippi.
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They commonly grow alongside Peltogyne purpurea, Caryocar costaricense, and Qualea paraensis. An adult tree is very flood tolerant, capable of withstanding long-term submersion. Despite this, early seedlings can only survive a few weeks in flooded conditions, limiting the range of environments Parkia pendula can thrive in.Scarano, F.R. and R.M. Crawford, Ontogeny and the concept of anoxia-tolerance: the case of the Amazonian leguminous tree Parkia pendula.
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Haematopoietic cells, in bone marrow, are sensitive to anoxia and are the first to die after reduction or removal of the blood supply. In anoxic conditions they usually die within 12 hours. Experimental evidence suggests that bone cells composed of osteocytes, osteoclasts, and osteoblasts die within 12–48 hours, and marrow fat cells die within 120 hours. The death of bone does not alter its radiographic opacity nor its mineral density.
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As the condition progresses, there is an increase in echogenicity of the corpora cavernosa, attributed to tissue edema. Eventually, changes in the echotexture of the corpora cavernosa can be observed due to the fibrotic transformation generated by tissue anoxia. In high-flow priapism normal or increased, turbulent blood flow in the cavernous arteries is seen. The area surrounding the fistula presents a hypoechoic, irregular lesion in the cavernous tissue.
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Another mechanism involves effects on the mitochondrial respiratory enzyme chain that is responsible for effective tissue utilization of oxygen. Carbon monoxide binds to cytochrome oxidase with less affinity than oxygen, so it is possible that it requires significant intracellular hypoxia before binding. This binding interferes with aerobic metabolism and efficient adenosine triphosphate synthesis. Cells respond by switching to anaerobic metabolism, causing anoxia, lactic acidosis, and eventual cell death.
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There are several hypotheses for the causes of these extinctions. There is evidence that major changes in the carbon cycle and sea level occurred during this time. Evidence also exists for the development of anoxia (a loss of oxygen) in some environments in the oceans. One hypothesis that unifies this evidence links these environmental changes to widespread volcanic eruptions caused by the emplacement of the Kalkarindji Large Igneous Province or LIP.
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In 1952, Henry and Scoville recorded the electrical activity of patients during lobotomy and found the burst suppression pattern present in the recorded electrical activity. In 1963, Fischer-Williams and Cooper found the pattern present in patients suffering from cerebral anoxia, hypoxia, and various types of intracortical lesions. Treiman et al. observed the pattern in deep coma, various infantile encephalopathies, and the final stages of deteriorated status epilepticus.
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Many of these blooms consist of more than one type of Karenia species. The cause of the blooms is still poorly understood. When a large bloom occurs, resources become limited, and this means greater competition for space and sunlight between several marine organisms—as the genus Karenia start dying they release their neurotoxins, which can kill fish and other organisms. The dense blooms can also cause animal mortalities through anoxia.
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Risk factors associated with steatosis are varied, and may include diabetes mellitus, protein malnutrition, hypertension, cell toxins, obesity, anoxia, and sleep apnea. Steatosis reflects an impairment of the normal processes of synthesis and elimination of triglyceride fat. Excess lipid accumulates in vesicles that displace the cytoplasm. When the vesicles are large enough to distort the nucleus, the condition is known as macrovesicular steatosis; otherwise, the condition is known as microvesicular steatosis.
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Eleven distinct flood basalt episodes occurred in the past 250 million years, resulting in large volcanic provinces, creating lava plateaus and mountain ranges on Earth. Large igneous provinces have been connected to five mass extinction events. The timing of six out of eleven known provinces coincide with periods of global warming and marine anoxia/dysoxia. Thus, suggesting that volcanic CO2 emissions can force an important effect on the climate system.
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As aerobic respiration decreases, the plants become oxygen deficient, since the roots are unable to produce enough oxygen in the reduced soil conditions. Decreased oxygen uptake can also decrease plant productivity.Mendelssohn I.A., McKee K.L., Patrick, W.H. (1981) "Oxygen deficiency in Spartina alterniflora roots: Metabolic adaptation to anoxia". Science 214: 439–441 To gain energy, these plants then go through a process of alcoholic fermentation (Mendelssohn et al. 1981).
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Marine life partially rediversified during the cold period and a new cold-water ecosystem, the "Hirnantia biota", was established. The second pulse of extinction occurred in the later half of the Hirnantian as the glaciation abruptly recedes and warm conditions return. The second pulse is associated with intense worldwide anoxia (oxygen depletion) and euxinia (toxic sulfide production), which persist into the subsequent Rhuddanian stage of the Silurian Period.
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Presence of euxinia in the world's ancient deep oceans. According to Canfield, the deep ocean became sulfitic around 1.8 billion years ago and stayed that way for much of the boring billion. Periodic euxinia dominated through the Late Devonian Kelwasser events, and then most likely disappeared during the Carboniferous. Euxinia reemerged at the Permian-Triassic Boundary, and may have been present during the Ocean Anoxia Events of the Mesozoic.
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Bottom-trawl surveys and pelagic-species acoustic surveys are used to assess changes in fish biodiversity and abundance in LMEs. Fish populations can be surveyed for stock identification, length, stomach content, age-growth relationships, fecundity, coastal pollution and associated pathological conditions, as well as multispecies trophic relationships.Sea Around Us Project at www.seaaroundus.org/ Fish trawls can also collect sediment and inform us about ocean-bottom conditions such as anoxia.
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Graham's studies focused on child and developmental psychology. While little is known about Graham's early life, she graduated with a Ph.D. in Psychology from Yale University in 1942. After graduating from Yale, Graham went on to work at Washington University where she studied anoxia in newborns. She continued her research at the University of Wisconsin-Madison, and in 1986 she became a professor at the University of Delaware. Prof.
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The boundary between the Ordovician and Silurian periods is marked by repetitive periods of anoxia, interspersed with normal, oxic conditions. In addition, anoxic periods are found during the Silurian. These anoxic periods occurred at a time of low global temperatures (although levels were high), in the midst of a glaciation. Jeppsson (1990) proposes a mechanism whereby the temperature of polar waters determines the site of formation of downwelling water.
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As a glycogen phosphorylase, GPBB catalyzes the phosphorolysis of glycogen to yield glucose 1-phosphate. This reaction serves as the rate-determining first step in glycogenolysis and, thus, contributes to the regulation of carbohydrate metabolism. In particular, GPBB is responsible for supplying emergency glucose during periods of stress, including anoxia, hypoglycemia, or ischemia. In normal cell conditions, GPBB is bound to the sarcoplasmic reticulum (SR) membrane by complexing with glycogen.
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There has been some speculation that using pulses of fertilization (around 20 days in length) may be more effective at getting carbon to ocean floor than sustained fertilization. There is some controversy over seeding the oceans with iron however, due to the potential for increased toxic phytoplankton growth (e.g. "red tide"), declining water quality due to overgrowth, and increasing anoxia in areas harming other sea-life such as zooplankton, fish, coral, etc.
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High levels of NO3 in water can adversely affect oxygen levels for both humans and aquatic systems. Human health issues include methemoglobinemia and anoxia, commonly referred to as blue baby syndrome. As a result of these toxic effects, regulatory agencies limit the amount of NO3 permissible in drinking water to 45–50 mg1-1. Eutrophication, a decline in oxygen content of water, of aquatic systems can cause the death of fish and other marine species.
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539 ;Toarcian During deposition of the Rydebäck Member, the Toarcian turnover happened. This event at the Pliensbachian-Toarcian boundary characterized by widespread anoxic conditions globally, led to the extinction of various groups of flora and fauna. Taxa inhabiting the upper water column were unaffected by anoxia and included ammonites and belemnites. Epifaunal taxa adapted to low-oxygen conditions, such as the buchiids, posidoniids and inoceramids, flourished in the post-extinction environment during the survival interval.
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The affinity of large ornamented Ediacaran microfossils is a matter of current research. Like the resting cysts of some animals, these microfossils have three layers in their cell walls. If large ornamented Ediacaran microfossils represent animal resting stages, this would be consistent with frequent periods of oceanic anoxia in the Ediacaran period, which disappear in the Cambrian period. They are much larger than any known dinoflagellate, and dinoflagellate biomarkers are absent in the Ediacaran period.
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Normal blood circulation in the lower limbs of a horse depends in part on the horse moving about. Lack of sufficient movement, alone or in combination with other factors, can cause stagnant anoxia, which in turn can cause laminitis. A horse favoring an injured leg will both severely limit its movement and place greater weight on the other legs. This sometimes leads to static laminitis, particularly if the animal is confined in a stall.
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The filter feeding behavior of oysters can buffer against environmental degradation caused by human induced eutrophication of estuary systems. Oysters feed on suspended phytoplankton and other organic matter. Disruption of the filter feeding by oysters can lead to a decrease in the elimination of organic matter from the water column and increase phytoplankton abundance. This in turn may lead to seasonal anoxia, which could increase mortality for other estuary animals, such as fish.
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A special effects engineer positions the inflatable plastic tube feeding the smoke. Atmospheric effects generated using water and dry ice or liquid nitrogen can present asphyxiation or breathing hazards. Both carbon dioxide and nitrogen displace ordinary air and the oxygen it contains, creating a risk of subtle anoxia (lack of oxygenation) for people working in these atmospheres. Adequate ventilation is essential to ensure that artists and technicians are surrounded by breathable air.
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People who survive either because the cord or its anchor point of attachment breaks, or because they are discovered and cut down, can face a range of serious injuries, including cerebral anoxia (which can lead to permanent brain damage), laryngeal fracture, cervical spine fracture, tracheal fracture, pharyngeal laceration, and carotid artery injury. Ron M. Brown writes that hanging has a "fairly imperspicuous and complicated symbolic history".The Art of Suicide. Reaktion Books. p. 226.
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The story follows a man who is given an experimental drug to heal brain damage caused by anoxia after he nearly drowns. The drug regenerates his damaged neurons and has the unintended side effect of exponentially improving his intellect and motor skills. As he gets smarter and smarter, he is pursued by several government agencies and eventually receives a message from—and then enters into conflict with—another super-intelligent test subject.
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Then, following the 2015 drought, extreme temperatures and heightened salinity reduced the amount of oxygen that could remain dissolved in the water, causing periods of anoxia during nighttime and thereby damaging the health of the turtlegrass in the bay. During the summer and fall of 2015, approximately 40,000 areas of seagrass died. Red = area containing dead turtle grass in patches of varying size; not 100% dead. Yellow = mixed live/dead impacted areas.
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The prevalence of metabolic suppression use among fish species has not been thoroughly explored. This is partly because the metabolic rates of hypoxia-exposed fish, including suppressed metabolic rates, can only be accurately measured using direct calorimetry, and this technique is seldom used for fish. The few studies that have used calorimetry reveal that some fish species employ metabolic suppression in hypoxia/anoxia (e.g., goldfish, tilapia, European eel) while others do not (e.g.
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The Dufek Intrusion is a mafic layered intrusion that was emplaced into present-day Antarctica approximately 183 million years ago.S.D.Burgess, S.A.Bowring, T.H.Fleming & D.H.Elliot, 2015. High-precision geochronology links the Ferrar large igneous province with early-Jurassic ocean anoxia and biotic crisis. Earth and Planetary Science Letters, , Vol: 415, Page: 90-99 It comprises two outcropping sections called the Dufek Massif and the Forrestal Range that are thought to be connected beneath the Sallee Snowfield.
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The night before the 1999 UEFA Cup Final, a video tape was released which showed Cannavaro being injected with a substance. The substance was found to be neoton (phosphocreatine), which is used in cardiac surgery to protect the heart during periods of anoxia and stress. It is not on the banned substance list. This chemical is, in partnership with adenosine triphosphate (ATP), fundamental to the ability of the body to produce muscular energy.
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It was observed that it can survive in an environment without fresh oxygen (anoxia). Since 1977, Sømme has participated in several research expeditions to the Antarctic, where he studied arthropods (mites and springtails) on Bouvet Island and in Queen Maud Land. The fauna there have the same survival mechanisms as Sømme had found earlier in Norway's high mountains at Finse. On Bouvet Island, there are eight to ten species of mites and springtails.
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Though less toxic, ferrous iron (Fe2+) is another substance which commonly forms in anoxic waters. Anoxia is the most common culprit for the second pulse of the LOME and is connected to many other mass extinctions throughout geological time. It may have also had a role the first pulse of the LOME, though support for this hypothesis is inconclusive and contradicts other evidence for high oxygen levels in seawater during the glaciation.
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The Ordovician ocean also had very low levels of sulfate, a nutrient which would otherwise resupply 32S from the land. Pyrite forms most easily in anoxic and euxinic environments, while better oxygenation encourages the formation of gypsum instead. As a result, anoxia and euxinia would need to be common in the deep sea to produce enough pyrite to shift the δ34S ratio. A more direct proxy for anoxic conditions is FeHR/FeT.
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The late Hirnantian experienced a dramatic increase in the abundance of black shales. Coinciding with the retreat of the Hirnantian glaciation, black shale expands out of isolated basins to become the dominant oceanic sediment at all latitudes and depths. The worldwide distribution of black shales in the late Hirnantian is indicative of a global anoxic event. Molybdenum, uranium, and neodymium isotope excursions found in many different regions also correspond to widespread anoxia.
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The most likely culprits are cyanobacteria, which can use nitrogen fixation to produce usable nitrogen compounds in the absence of nitrates. Nitrogen isotopes during the anoxic event record high rates of denitrification, a biological process which depletes nitrates. The Nitrogen- fixing ability of cyanobacteria would give them an edge over inflexible competitors like eukaryotic algae. At Anticosti Island, a uranium isotope excursion consistent with anoxia actually occurs prior to indicators of receding glaciation.
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Forensic diagnosis of drowning is considered one of the most difficult in forensic medicine. External examination and autopsy findings are often non-specific, and the available laboratory tests are often inconclusive or controversial. The purpose of an investigation is generally to distinguish whether the death was due to immersion, or whether the body was immersed post mortem. The mechanism in acute drowning is hypoxemia and irreversible cerebral anoxia due to submersion in liquid.
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Approximately , the δ34S values in seawater sulfates began to vary more and those in sedimentary sulfates grew more negative. Researchers have interpreted this excursion as indicative of an increase in water column oxygenation with continued periods of anoxia in the deepest waters. Modern seawater sulfate δ34S values are consistently 21.0 ± 0.2‰ across the world's oceans, while sedimentary sulfides vary widely. Seawater sulfate δ34S and δ18O values exhibit similar trends not seen in sedimentary sulfide minerals.
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If this situation is not immediately identified and corrected, death will ensue from cerebral and cardiac anoxia. Of 4,460 claims in the American Society of Anesthesiologists (ASA) Closed Claims Project database, 266 (approximately 6%) were for airway injury. Of these 266 cases, 87% of the injuries were temporary, 5% were permanent or disabling, and 8% resulted in death. Difficult intubation, age older than 60 years, and female gender were associated with claims for perforation of the esophagus or pharynx.
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These are much more common in premature babies, particularly those under 1500 g at birth. Premature birth can be associated with problems that result in sensorineural hearing loss such as anoxia or hypoxia (poor oxygen levels), jaundice, intracranial haemorrhages, meningitis. Fetal alcohol syndrome is reported to cause hearing loss in up to 64% of infants born to alcoholic mothers, from the ototoxic effect on the developing fetus, plus malnutrition during pregnancy from the excess alcohol intake.
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Water stratification is when water masses with different properties - salinity (halocline), oxygenation (chemocline), density (pycnocline), temperature (thermocline) - form layers that act as barriers to water mixing which could lead to anoxia or euxinia. These layers are normally arranged according to density, with the least dense water masses sitting above the more dense layers. Water stratification also creates barriers to nutrient mixing between layers. This can affect the primary production in an area by limiting photosynthetic processes.
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Inferences from Pr/Ph on the redox potential of source sediments should always be supported by other geochemical and geological data, such as sulfur content or the C35 homohopane index (i.e. the abundance of C35 homohopane relative to that of C31-C35 homohopanes). For example, the Baghewala-1 oil from India has low Pr/Ph (0.9), high sulfur (1.2 wt.%) and high C35 homohopane index, which are consistent with anoxia during deposition of the source rock.
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Oceanic current modelling suggest that glaciation would have encouraged oxygenation in most areas, apart from the Paleo-Tethys ocean. Deep-sea anoxia is not the only explanation for the δ34S excursion of pyrite. Carbonate-associated sulfate maintains high 32S levels, indicating that seawater in general did not experience 32S depletion during the glaciation. Even if pyrite burial did increase at that time, its chemical effects would have been far too slow to explain the rapid excursion or extinction pulse.
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This would make the Hirnantian-Rhuddanian anoxia one of the longest-lasting anoxic events in geologic time. Cyanobacteria blooms after the Hirnantian glaciation likely caused the Hirnantian-Rhuddanian global anoxic event, the main factor behind the second extinction pulse. The cause of the Hirnantian-Rhuddanian anoxic event is uncertain. Like most global anoxic events, an increased supply of nutrients (such as nitrates and phosphates) would encourage algal or microbial blooms that deplete oxygen levels in the seawater.
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The sulfur would strip iron ions from the sea water, resulting in iron sulfide (pyrite), a portion of which was eventually buried. When sulfide became the major oceanic reductant instead of iron, the deep water became euxinic. This has become what is known as the Canfield ocean, a model backed by the increase in presence of δ34S in sedimentary pyrite and the discovery of evidence of the first sulfate evaporites. Anoxia and sulfidic conditions often occur together.
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Reperfusion injury, sometimes called ischemia-reperfusion injury (IRI) or reoxygenation injury, is the tissue damage caused when blood supply returns to tissue (re- + perfusion) after a period of ischemia or lack of oxygen (anoxia or hypoxia). The absence of oxygen and nutrients from blood during the ischemic period creates a condition in which the restoration of circulation results in inflammation and oxidative damage through the induction of oxidative stress rather than (or along with) restoration of normal function.
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In either hypothesis, the agent causing the injury is usually not known. Thalidomide is known to cause PFFD when the mother is exposed to it in the fifth or sixth week of pregnancy, and it is speculated that exposure to other toxins during pregnancy may also be a cause. Other etiologies that have been suggested, but not proven, include anoxia, ischemia, radiation, infection, hormones, and mechanical force. PFFD occurs sporadically, and does not appear to be hereditary.
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Honzik's research explored human development over the lifespan. Several of her most influential papers aimed to measure growth in the mental abilities of infants over the first year of life through brain development and changes in observable behaviors. She conducted pioneering work investigating developmental outcomes of infants with perinatal conditions, such as anoxia (oxygen deficiency). Honzik conducted a landmark longitudinal study of parenting behaviors in relation to their children's mental abilities, assessed from age 21 months to 30 years.
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The Permian Mass Extinction was thought to have been brought on by such ocean warming, stratification, deoxygenation, anoxia, and subsequent extinction of 96% of all marine species. Reduced vertical mixing and marine heatwaves have decimated seaweed ecosystems in many areas. Marine Permaculture mitigates this by restoring some vertical mixing and preserves these important ecosystems. By preserving and regenerating habitat offshore on a platform, Marine Permaculture employs natural processes to ensure conditions that regenerate an abundance of marine life.
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The incident was also discussed in a government report about "mothering under duress", which called Erika a "legend". She was the subject of an episode of Life's Little Miracles, a TV show on Discovery Health Channel and was mentioned in an episode of Nova on PBS titled Making Stuff Colder. Erika's experience was mentioned as one indication of the medical relevance of a Fred Hutchinson Cancer Research Center study on "anoxia-induced suspended animation" in zebrafish.
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Environmental cues such as flooding, drought, chilling, wounding, and pathogen attack can induce ethylene formation in plants. In flooding, roots suffer from lack of oxygen, or anoxia, which leads to the synthesis of 1-aminocyclopropane-1-carboxylic acid (ACC). ACC is transported upwards in the plant and then oxidized in leaves. The ethylene produced causes nastic movements (epinasty) of the leaves, perhaps helping the plant to lose less water in compensation for an increase in resistance to water transport through oxygen-deficient roots .
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The Aitoliko Lagoon ( Limnothalassa Aitolikou) is a lagoon located in the south of Aetolia-Acarnania, Greece. It is separated from the larger Missolonghi Lagoon (a bay of the Gulf of Patras) to the south by the island of Aitoliko, but together they form the Missolonghi–Aitoliko Lagoons complex. Its maximum depth is 28 metres.A. Gianni and I. Zacharias, University of Ioannina, Morphology and anoxia in enclosed seas: Aitoliko lagoon - Greece At a salinity of 19-28 PSU, its water is brackish.
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As a result of these restrictive conditions, anoxic conditions frequently occurred during the deposition of the sediments that form the Haynesville Shale. Anoxic bottom water conditions allowed organic matter falling to the floor of this basin to be preserved and incorporated into sediments that became the Haynesville Shale. The mechanisms by which organic matter accumulated within these sediments consisted of a complex interplay of local carbonate generation, clastic input from outside sources, variable burial rates, and variable bottom water anoxia and euxinia.
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Van der Giezen has published extensively in his field of research and made over 50 contributions as external seminars and lectures at international scientific meetings. Van der Giezen investigates adaptations of microbial eukaryotes to life under anoxia, or low oxygen. He discovered mitochondrial remnants (mitosomes) in the human intestinal parasite Giardia intestinalis,Nature (2003) 426: 172-176 an organism until then considered to be one of the most primitive eukaryotes. This discovery called for re- assessment of the evolution of mitochondria.
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Eutrophication is a common phenomenon in coastal waters. In contrast to freshwater systems where phosphorus is often the limiting nutrient, nitrogen is more commonly the key limiting nutrient of marine waters; thus, nitrogen levels have greater importance to understanding eutrophication problems in salt water. Estuaries, as the interface between freshwater and saltwater, can be both phosphorus and nitrogen limited and commonly exhibit symptoms of eutrophication. Eutrophication in estuaries often results in bottom water hypoxia/anoxia, leading to fish kills and habitat degradation.
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Anoxia and sepsis are the most frequent causes at birth, while adrenal insufficiency often manifests in neonates. According to the degree and rate of hemorrhage, its clinical manifestations can vary widely. The non-specific signs and symptoms in prominent underlying diseases often prevents prompt recognition and proper treatment of the condition, which may result in adrenal crisis, shock, and death. Although the mortality rate varies with the severity of the underlying inductive disease, adrenal hemorrhage is related to 15% of the deaths.
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Some geologists have argued that anoxia played a role in the first extinction pulse, though this hypothesis is controversial. In the early Hirnantian, shallow-water sediments throughout the world experience a large positive excursion in the δ34S ratio of buried pyrite. This ratio indicates that shallow-water pyrite which formed at the beginning of the glaciation had a decreased proportion of 32S, a common lightweight isotope of sulfur. 32S in the seawater could hypothetically be used up by extensive deep-sea pyrite deposition.
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Chemical cycle disturbances would also steepen the chemocline, restricting the habitable zone of planktonic fauna which also go extinct in the first pulse. This scenario is congruent with both organic carbon isotope excursions and general extinction patterns observed in the first pulse. However, data supporting deep-water anoxia during the glaciation contrasts with more extensive evidence for well-oxygenated waters. Black shales, which are indicative of an anoxic environment, become very rare in the early Hirnantian compared to surrounding time periods.
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Although early Hirnantian black shales can be found in a few isolated ocean basins (such as the Yangtze platform of China), from a worldwide perspective these correspond to local events. Some Chinese sections record an early Hirnantian increase in the abundance of Mo-98, a heavy isotope of molybdenum. This shift can correspond to a balance between minor local anoxia and well-oxygenated waters on a global scale. Other trace elements point towards increased deep-sea oxygenation at the start of the glaciation.
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At least in European sections, late Hirnantian anoxic waters were originally ferruginous (dominated by ferrous iron) before gradually becoming more euxinic. In China, the second extinction pulse occurs alongside intense euxinia which spreads out from the middle of the continental shelf. On a global scale, euxinia was probably one or two orders of magnitude more prevalent than in the modern day. Global anoxia may have lasted more than 3 million years, persisting through the entire Rhuddanian stage of the Silurian period.
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Anaerobic glycolysis leads to lactate overload, which the turtle buffers to some extent by increased shell and bone CaCO3 production. However, glycolysis is not efficient for ATP production, and in order to maintain an optimum ATP concentration, the turtle's brain reduces its ATP consumption by suppressing its neuronal activity and gradually releasing adenosine. This re-establishes the ATP consumption/production balance, which is then maintained by reducing ion conductance and releasing GABA. The decrease in neuronal activity renders the turtle comatose for the duration of anoxia.
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When a bomber develops mechanical problems and the crew is ordered to bail out, Tom Hughes panics in fear and refuses to jump. His friend (and another suitor of Burt Hughes), Cadet Jim Carter (Walter Reed), crash- lands the aircraft, claiming that he is the one who panicked, but Hughes confesses afterward. Facing an elimination board, he successfully persuades Davis and receives a second chance. On a subsequent flight, Buck Oliver passes out from anoxia, nearly tossing Carter out of the opened bomb bay without a parachute.
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Hypoxia in which there is complete deprivation of oxygen supply is referred to as anoxia. Generalized hypoxia occurs in healthy people when they ascend to high altitude, where it causes altitude sickness leading to potentially fatal complications: high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE). Hypoxia also occurs in healthy individuals when breathing mixtures of gases with a low oxygen content, e.g. while diving underwater especially when using closed-circuit rebreather systems that control the amount of oxygen in the supplied air.
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Normally, organic carbon is decayed before it is rotted. Anoxia can prevent decay, but the prevalence of bioturbation associated with body fossils indicates that many BS sites were oxygenated when the fossils were deposited. It seems that the reduced permeability associated with the clay particles that make up the sediment restricted oxygen flow; furthermore, some beds may have been 'sealed' by the deposition of a carbonate cement. The chemistry of the clay particles that buried the organisms seems to have played an important role in preservation.
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Hypoventilation (also known as respiratory depression) occurs when ventilation is inadequate (hypo meaning "below") to perform needed respiratory gas exchange. By definition it causes an increased concentration of carbon dioxide (hypercapnia) and respiratory acidosis. Hypoventilation is not synonymous with respiratory arrest, in which breathing ceases entirely and death occurs within minutes due to hypoxia and leads rapidly into complete anoxia, although both are medical emergencies. Hypoventilation can be considered a precursor to hypoxia and its lethality is attributed to hypoxia with carbon dioxide toxicity.
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Adults are light brown above, with scattered darker spots and indistinct saddles. Epaulette sharks have nocturnal habits and frequent shallow water on coral reefs or in tidal pools. This shark has evolved to cope with the severe night time oxygen depletion (hypoxia) in isolated tidal pools by increasing the blood supply to its brain and selectively shutting down non-essential neural functions. It is capable of surviving complete anoxia for an hour without ill effects, and at a much higher temperature than most other hypoxia-tolerant animals.
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BioEssays 31: 1091–1099 bioenergetics of plant cells, Igamberdiev, A.U., Kleczkowski, L.A. (2011) Magnesium and cell energetic in plants under anoxia. Biochem. J. 437: 373–379Igamberdiev, A.U., Hill, R.D. (2018) Elevation of cytosolic Ca2+ concentration in response to energy deficiency in plants: the general mechanism of adaptation to low oxygen stress. Biochem. J. 475: 1411–1425 plant enzymology,Igamberdiev, A.U., Gardeström, P. (2003) Regulation of NAD- and NADP-dependent isocitrate dehydrogenases by reduction levels of pyridine nucleotides in mitochondria and cytosol of pea leaves. Biochim. Biophys.
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However, drawing conclusion on the oxic state of depositional environments only from Pr/Ph ratio can be misleading because salinity often controls the Pr/Ph in hypersaline environments. In another example, the decrease in Pr/Ph during deposition of the PermianKupferschiefer sequence in Germany is in coincidence with an increase in trimethylated 2-methyl-2-(4,8,12-trimethyltridecyl)chromans, an aromatic compound believed to be markers of salinity. Therefore, this decrease in Pr/Ph should indicate an increase in salinity, instead of an increase in anoxia.
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Coastal regions, such as the Baltic Sea, the northern Gulf of Mexico, and the Chesapeake Bay, as well as in large enclosed water bodies like Lake Erie, have been affected by deoxygenation due to eutrophication. Excess nutrients are input into these systems by rivers, ultimately from urban and agricultural runoff and exacerbated by deforestation. These nutrients lead to high productivity that produces organic material that sinks to the bottom and is respired. The respiration of that organic material uses up the oxygen and causes hypoxia or anoxia.
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He suffered from a heart attack that caused damage to his brain secondary to cerebral anoxia. Due to his injury, he developed severe selective amnesia for the people and dates associated with both personal and public events. Though he could describe what happened during the event as well as the setting of the event, he could not give any information about the event's date or the people involved. His amnesia was temporally limited, affecting only his memories of the last two to three decades.
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The 1922 Nobel Prize in Physiology or Medicine winner Archibald Hill proposed in 1924 that the heart was protected from anoxia in strenuous exercise by the existence of a governor. This hypothesis was disregarded and further research upon exercise fatigue was modeled in terms of it being due to a mechanical failure of the exercising muscles ("peripheral muscle fatigue"). This failure was caused either by an inadequate oxygen supply to the exercising muscles, lactic acid buildup, or total energy depletion in the exhausted muscles.Edwards RHT.
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This human intervention has also brought negative results in the quality of the water, after decades of toxic waste dumping causing a situation of anoxia (lack of oxygen), which almost eliminated the entire fauna and flora. However, in recent years this situation is being reversed, thanks to a dumping ban and natural regeneration. now it is possible to observe algae, tonguefishes, crabs, and seabirds, as well as occasional bathers in the summer months. The estuary is also a natural border for several neighbourhoods and districts within the borough.
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Since the crucian carp has a more efficient strategy to prevent lactate buildup than C. picta, the initial glycolysis continues without ceasing, a process called the Pasteur effect. In order to keep up with this fast glucose metabolism via glycolysis, as well as maintain the balance between ATP production and consumption, the crucian carp moderately suppresses its motor activities, releases GABA, and selectively suppresses some unnecessary sensory functions. Crucian carp also counteracts the damaging effects of anoxia by swimming into cooler water, a phenomenon known as voluntary hypothermia.
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Global anoxia during the latest Pliensbachian and the earliest Toarcian occurred in close association with regional drowning of the lower Liassic platforms and localized deposition of basinal marls. From Toarcian times, carbonate platforms of the Azilal Formation developed in the margins of the central High Atlas basin, whereas the basin axis was occupied by a mixed carbonate-siliciclastic platform system prograding eastward to basinal deposits. This mixed system progressively graded to an extensive shallow water carbonate platform of the Anoual Formation, Bajocian to early Bathonian in age that is recognized throughout the central High Atlas.
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The Chinese State Oceanic Administration has warned that the algae could threaten marine life and local tourism, and other scientists have stated that the bloom could decompose on beaches and release toxic gases if not cleaned up. Close to 4,000 tonnes a day of algae is being removed from the bloom, to be sent off and used as animal feed or fertilizer. Green and red tides have become more common in China in recent years. The green tides from the current algal blooms can also result in dead zones from localized ocean anoxia.
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A wide range of physiological theories of the NDE have been put forward including those based upon cerebral hypoxia, anoxia, and hypercapnia; endorphins and other neurotransmitters; and abnormal activity in the temporal lobes. Neurobiological factors in the experience have been investigated by researchers in the field of medical science and psychiatry.Mayank and Mukesh, 2004; Jansen, 1995; Thomas, 2004; Fenwick and Fenwick 2008 Among the researchers and commentators who tend to emphasize a naturalistic and neurological base for the experience are the British psychologist Susan Blackmore (1993), with her "dying brain hypothesis".
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Some species show a remarkable tolerance for hydrogen sulfide and anoxia. They can be quite abundant in some areas. In an Alaskan bay as many as 85 adult individuals of Priapulus caudatus per square meter has been recorded, while the density of its larvae can be as high as 58,000 per square meter.Kingdoms and Domains: An Illustrated Guide to the Phyla of Life on Earth Together with Echiura and Sipuncula, they were once placed in the taxon Gephyrea, but consistent morphological and molecular evidence supports their belonging to Ecdysozoa, which also includes arthropods and nematodes.
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Euthanasia can be accomplished either through an oral, intravenous, or intramuscular administration of drugs, or by oxygen deprivation (anoxia), as in some euthanasia machines. In individuals who are incapable of swallowing lethal doses of medication, an intravenous route is preferred. The following is a Dutch protocol for parenteral (intravenous) administration to obtain euthanasia: Intravenous administration is the most reliable and rapid way to accomplish euthanasia. A coma is first induced by intravenous administration of 20 mg/kg sodium thiopental (Nesdonal) in a small volume (10 ml physiological saline).
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The most quoted explanation is that belemnites were semelparous and died shortly after spawning, much like modern coleoids which migrate from the ocean to the shelf area. In battlefields comprising both adults and juveniles—as the former model would consist entirely of adults—large groups of belemnites may have been killed by volcanism, changes in salinity or temperature, harmful algal blooms (and, thereby, anoxia), or mass stranding. Another popular theory is that the guards were simply moved or redeposited by ocean currents into large aggregations. Some battlefields may be regurgitated indigestible matter from a predator.
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Since 2002, seasonal hypoxia has been observed annually to extend over an area >820 km2 along the Oregon coastal shelf region in the summer months. Samples of dissolved oxygen (DO) point to the fact that in the summer months, bottom waters at Heceta Head line (44.0 N, respectively) were consistently hypoxic, or falling between 43–64 micromolar(µm) of O2. In 2006, anoxia was first observed on the Oregon inner shelf. In August 2006, surveys along the central Oregon coast transect lines revealed the complete absence of all fish from rocky reefs.
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The Fink effect, also known as "diffusion anoxia", "diffusion hypoxia", or the "third gas effect", is a factor that influences the pO2 (partial pressure of oxygen) within the alveolus. When water-soluble gases such as anesthetic agent N2O (nitrous oxide) are breathed in large quantities they can be dissolved in body fluids rapidly. This leads to a temporary increase in both the concentrations and partial pressures of oxygen and carbon dioxide in the alveolus. The effect is named for Bernard Raymond Fink (1914–2000), whose 1955 paper first explained it.
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The oxygen effect is quantified by measuring the radiation sensitivity or Oxygen Enhancement Ratio (OER) of a particular biological effect (e.g., cell death or DNA damage), which is the ratio of doses under pure oxygen and anoxic conditions. Consequently, OER varies from unity in anoxia to a maximum value for 100% oxygen of typically up to three for low ionizing-density-radiation (beta-, gamma-, or x-rays), or so-called low linear energy transfer (LET) radiations. Radiosensitivity varies most rapidly for oxygen partial pressures below ~1% atmospheric (Fig. 1).
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This interval is also known as the Sandwick Fish Bed Member in Orkney and a series of other equivalent fish beds in Shetland and on the south side of the Moray Firth. A thick lake interval of similar age is also found in East Greenland. This deep lake interval is dated as late Eifelian and is correlated to the global Kačák Event of marine anoxia, which was associated with significant extinctions. The increase in lake size is explained as the result of an intensification of the monsoon system.
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Spewing of sewage, industrial and fishery wastes leads to anthropogenic eutrophication, where there is excess augmentation of ammonia; a principal nitrogen source for certain species of Tetraspora. The excess nitrogen is proposed to contribute to uncontrolled cell proliferation of Tetraspora colonies; resulting in algal blooms. Tetraspora blooms have negative effects on the overall environmental ecology because they shift and alter the chemical properties of the water. This is because with the mass growth, hypoxia and/or anoxia can occur and these may have detrimental effects on biodiversity and survivability of other organisms such as fish.
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Philosophies 3: 30 and dynamics of social systems. Igamberdiev, A.U. (2017) Evolutionary transition from biological to social systems via generation of reflexive models of externality. Prog. Biophys. Mol. Biol. 131: 336–347 Abir Igamberdiev has contributed to the characterization of metabolic pathways and enzymes of plant respiratory metabolism and to the discovery that plant mitochondria use nitrite as an alternative electron acceptor under anoxia (anaerobic respiration) and produce nitric oxide, which is scavenged by phytoglobin. He developed the concept of thermodynamic buffering in metabolism that supports stable non-equilibrium dynamics of living systems.
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Isorenieratene is a carotenoid light harvesting pigment with the chemical formula C40H48. Isorenieratene and its derivatives are useful to marine chemists studying the carbon cycle as biomarkers that indicate photic zone anoxia. Isorenieratene is produced by green sulfur bacteria (Chlorobium) which perform photosynthesis using hydrogen sulfide rather than water: :H2S + CO2 → SO42− \+ organic compounds Such anoxygenic photosynthesis requires reduced sulfur (and therefore strictly anaerobic conditions) and light (hν). This combination of conditions is very unusual nowadays, since it requires very stratified water columns to achieve a sharp density gradient, i.e.
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Agonal respiration, gasping respiration or agonal breathing is a distinct abnormal pattern of breathing and brainstem reflex characterized by gasping, labored breathing, accompanied by strange vocalizations and myoclonus. Possible causes include cerebral ischemia, extreme hypoxia (inadequate oxygen supply to tissue) or even anoxia (total depletion of oxygen). Agonal breathing is an extremely serious medical sign requiring immediate medical attention, as the condition generally progresses to complete apnea and heralds death. The duration of agonal respiration can be as brief as two breaths or last up to several hours.
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One possible explanation for the short anaerobic half life is the observation that alachlor is rapidly transformed under anoxia to up to 14 degradation products in the presence of iron-bearing ferruginous smectites. The iron in such minerals can be used by certain soil bacteria as an electron acceptor when soils are flooded, thus the process of herbicide transformation by reduced clay is thought to be microbially mediated.Xu, J., J. W. Stucki, J. Wu, J. Kostka, and G. K. Sims. 2001. Fate of atrazine and alachlor in redox-treated ferruginous smectite.
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Cold seeps and hydrothermal vents of deep oceans are communities that do not rely on photosynthesis for food and energy production. These systems are largely driven by chemosynthetic derived energy. Both systems share common characteristics such as the presence of reduced chemical compounds (H2S and hydrocarbonates), local hypoxia or even anoxia, a high abundance and metabolic activity of bacterial populations, and the production of autochthonous, organic material by chemoautotrophic bacteria. Both hydrothermal vents and cold seeps show regularly, highly increased levels of metazoan biomass in association with a low local diversity.
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A Zahn infarct is a pseudo-infarction of the liver, consisting of an area of congestion with parenchymal atrophy but no necrosis, and usually due to obstruction of a branch of the portal vein. Zahn infarcts are unique in that there is collateral congestion of liver sinusoids that do not include areas of anoxia seen in most infarcts. Fibrotic tissue may develop in the area of the infarct and it could be caused by an occlusive phlebitis in portal vein radicles. Non ischemic infarct of liver with lines of Zahn.
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Gondelellids and many other Permian species in the area disappeared, but ecologically tolerant Hindeodus survived and dominated the area. A similar situation occurred in Iran where Gondelellids were abruptly replaced by the Hindeodus in the deep-water areas. There is evidence that Hindeodus was able to migrate during the Permian Triassic transitional period which lead to its wide distribution worldwide during this time. They were able to survive and evolve in warm-water or cold water and shallow water or deep- water environments despite widespread anoxia during the Permian-Triassic transitional period.
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The Capitanian stage was between 265.1 ± 0.4 – 259.8 ± 0.4 Mya. The Guadalupian ended with a deteriorating environment, Greenhouse conditions, and several series of mass-extinctions; both the great dinocephalians, other taxa on land and various invertebrates in the sea. They would be succeeded by new types of mammal-like reptiles. A significant mass extinction event (the End-Capitanian extinction event) occurred at the end of this epoch, which was associated with anoxia and acidification in the oceans and possibly caused by the volcanic eruptions that produced the Emeishan Traps.
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Warnick and Bergstrom also showed that cooling the kidney immediately after removal markedly reduced any further ATP loss. When these non warm-injured kidneys were perfused with oxygenated hypothermic plasma, ATP levels were reduced by 50% after 24-hour storage and, after 48 hours, mean tissue ATP levels were a little higher than this indicating that synthesis of ATP had occurred. Pegg has shown that rabbit kidneys can resynthesize ATP after a period of perfusion storage following warm injury, but no resynthesis occurred in non warm-injured kidneys. Warm anoxia can also occur during reimplantation of the kidney after storage.
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It is located south of Oakley, Kansas. At a few times during the late Cretaceous the Western Interior Seaway went through periods of anoxia, where the bottom water was devoid of oxygen and the water column was stratified. At the end of the Cretaceous, a continuing uplift in a mountain- building episode called the Laramide orogeny hoisted the sandbanks (sandstone) and muddy brackish lagoons (shale) – the thick sequences of silt and sandstone still seen today as the Laramie Formation – while low-lying basins between them gradually subsided. The Western Interior Seaway divided across the Dakotas and retreated south towards the Gulf of Mexico.
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Variables that are considered, and often summarized by researchers, include: anoxia; cerebral hypoxia;Parnia S, Spearpoint K, Fenwick PB. "Near death experiences, cognitive function and psychological outcomes of surviving cardiac arrest". Resuscitation. 2007 Aug;74(2):215–21. hypercarbia; endorphins; serotonin or various neurotransmitters; temporal lobe dysfunction or seizures;Britton W. B., Bootzin R. R. "Near-death experiences and the temporal lobe". Psychol. Sci. 15, 254–258, 2004 the NMDA receptor; activation of the limbic system; drugs; retinal ischemia; and processes linked to rapid eye-movement (REM) sleep or phenomena generated on the border between sleep and wakefullness.
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These sources increase the biochemical oxygen demand in the waters where they are discharged which leads to the depletion of dissolved oxygen in the water and often causes anoxia. Legislation has banned the direct discharge of vinasse onto surface waters, leading it to be mixed with waste water from the sugarcane washing process to be reused as organic fertilizer on sugarcane fields. Despite this ban, some small sugarcane mills still discharge vinasse into streams and rivers due to a lack of transportation and application resources. Furthermore, vinasse is sometimes mishandled in storage and transport in mills.
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Because this is not a complete cessation of metabolic rate, metabolic suppression can only prolong hypoxic survival, not sustain it indefinitely. If the hypoxic exposure lasts sufficiently long, the fish will succumb to a depletion of its glycogen stores and/or the over- accumulation of deleterious anaerobic end-products. Furthermore, the severely limited energetic scope that comes with a metabolically suppressed state means that the fish is unable to complete critical tasks such a predator avoidance and reproduction. Perhaps for these reasons, goldfish prioritize their use of aerobic metabolism in most hypoxic environments, reserving metabolic suppression for the extreme case of anoxia.
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Degradation can be deforestation, desertification, soil erosion, mineral depletion, or chemical degradation (acidification and salinization). Agriculture lead to rise in Zoonotic disease like the Coronavirus disease 2019, by degrading natural buffers between humans and animals, reducing biodiversity and creating big groups of genetically similar animals. Eutrophication, excessive nutrients in aquatic ecosystems resulting in algal bloom and anoxia, leads to fish kills, loss of biodiversity, and renders water unfit for drinking and other industrial uses. Excessive fertilization and manure application to cropland, as well as high livestock stocking densities cause nutrient (mainly nitrogen and phosphorus) runoff and leaching from agricultural land.
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After opening the nest entrance, the oxygen concentration increased again, but for a 100 mm long nest it took nearly 20 minutes before the concentration was back to the normal depressed level. The dilemma faced by C. anderseni is to avoid drowning without suffering anoxia or hypercapnia, and they show a remarkable ability to adapt to the extreme conditions in the mangrove and exploit a niche where the density of other ants is insignificant. By adapting to these hostile situations, mangrove ants have developed the ability to switch to anaerobic respiration. This was proven by the observed oxygen and carbon dioxide levels.
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It is a common misconception that anaerobic conditions are necessary for the preservation of soft tissue; indeed much decay is mediated by sulfate-reducing bacteria which can only survive in anaerobic conditions. Anoxia does, however, reduce the probability that scavengers will disturb the dead organism, and the activity of other organisms is undoubtedly one of the leading causes of soft- tissue destruction. Plant cuticle is more prone to preservation if it contains cutan, rather than cutin. Plants and algae produce the most preservable compounds, which are listed according to their preservation potential by Tegellaar (see reference).
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Thus cells get less glucose than they normally do, which causes an "energy crisis". Concurrently with these processes, the activity of mitochondria may be reduced, which causes cells to rely on anaerobic metabolism to produce energy, increasing levels of the byproduct lactate. For a period of minutes to days after a concussion, the brain is especially vulnerable to changes in intracranial pressure, blood flow, and anoxia. According to studies performed on animals (which are not always applicable to humans), large numbers of neurons can die during this period in response to slight, normally innocuous changes in blood flow.
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The Steptoean Positive Carbon Isotope Excursion (SPICE) was a geological event which occurred about 500 million years ago at the end of the Cambrian Period. The SPICE event was a sudden reversal of the anoxia (lack of oxygen) that had steadily spread throughout the oceans during the Cambrian which also affected the atmosphere. After the SPICE event, oxygen levels recovered and levels in the atmosphere may have risen as high as 30%, higher than the 21% of the atmosphere that prevails today. The sudden increase in oxygen led to an explosion of life across the globe.
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Because the methane hydrates are unstable, except at cool temperatures and high (deep) pressures, scientists have observed smaller "burps" due to tectonic events. Studies suggest the huge release of natural gas could be a major climatological trigger, methane itself being a greenhouse gas many times more powerful than carbon dioxide. However, anoxia was also rife during the Hirnantian (late Ordovician) ice age. Oceanic anoxic events have been recognized primarily from the already warm Cretaceous and Jurassic Periods, when numerous examples have been documented, but earlier examples have been suggested to have occurred in the late Triassic, Permian, Devonian (Kellwasser event), Ordovician and Cambrian.
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His studies have identified molecular mechanisms that underlie metabolic arrest across phylogeny and that support phenomena including mammalian hibernation, estivation, and anoxia and ischemia tolerance. Control mechanisms include transcription factor changes that alter gene expression, and reversible phosphorylation of key metabolic enzymes by protein kinases and protein phosphatases. These studies across multiple species also hold key applications for medical science, particularly for preservation technologies that aim to extend the survival time of excised organs in cold or frozen storage. Additional applications include insights into hyperglycemia in metabolic syndrome and diabetes, and anoxic and ischemic damage caused by heart attack and stroke.
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During the late Cretaceous widespread conditions of oceanic anoxia occurred across the Cenomanian–Turonian (C-T) stage boundary between about 94.2 and 93.5 million years ago (Oceanic Anoxic Event II, OAE II). This Cenomanian–Turonian Boundary Event is reflected by one of the most extreme carbon cycle perturbations in Earth's history. Studies have been done on the marine reptiles to determine the impact of OAE II on the biodiversity of the group in the Western Interior Seaway. Results from that study seem to suggest that at least locally the OAE II had little to no effect on marine reptile diversity.
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These adaptations to life under the sediment provide protection for the worm from desiccation and predation while providing a plentiful supply of food and oxygen. At low tide, when the sediment in which the lugworm is living is no longer covered by water, aerial respiration takes place.The Effects of Oxygen Concentration and Anoxia on Respiration of Abarenicola pacifica and Lumbrineris zonata (Polychaeta) When feeding, A. pacifica everts its oesophagus (which then resembles a mushroom) and engulfs a "mouthful" of sand before restoring the oesophagus to its rightful position. Organic detritus and organisms such as nematodes, diatoms, bacteria and microphytes Abarenicola pacifica are ingested with the sand and digested in the gut.
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Patz proposed a clinical study to test his hypothesis, but the National Institutes of Health refused to fund the study on ethical grounds, fearing the study would "kill a lot of babies by anoxia to test a wild idea." Unable to obtain a grant, Patz borrowed money from his family to conduct a clinical study at Gallinger in the early 1950s. Patz conducted the study between 1951 and 1953 in conjunction with Leroy Hoeck (1911–2009), a pediatrician who was in charge of the newborn nursery at Gallinger. In the study, some infants were given concentrated oxygen, and others were given concentrated oxygen only if they showed signs of respiratory distress.
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The symptoms of generalized hypoxia depend on its severity and acceleration of onset. In the case of altitude sickness, where hypoxia develops gradually, the symptoms include fatigue, numbness / tingling of extremities, nausea, and cerebral anoxia. These symptoms are often difficult to identify, but early detection of symptoms can be critical. In severe hypoxia, or hypoxia of very rapid onset, ataxia, confusion / disorientation / hallucinations / behavioral change, severe headaches / reduced level of consciousness, papilloedema, breathlessness, pallor, tachycardia, and pulmonary hypertension eventually leading to the late signs cyanosis, slow heart rate / cor pulmonale, and low blood pressure followed by heart failure eventually leading to shock and death.
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That being so, proper caution must be exercised in accepting a diagnosis of its permanent loss before all cerebral blood flow has permanently ceased. The ability to breathe spontaneously depends upon functioning elements in the medulla – the 'respiratory centre'. In the UK, establishing a neurological diagnosis of death involves challenging this centre with the strong stimulus offered by an unusually high concentration of carbon dioxide in the arterial blood, but it is not challenged by the more powerful drive stimulus provided by anoxia – although the effect of that ultimate stimulus is sometimes seen after final disconnection of the ventilator in the form of agonal gasps.
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The organisms' presence shows that oxygen was present, but at worst this "paused" the mineralisation process. It seems that whilst anoxia improves Burgess Shale-type preservation, it is not essential to the process. In addition to the organic films, parts of many Burgess Shale creatures are preserved by phosphatisation: The mid-gut glands of arthropods often host a concentration of high reactivity phosphates, making them the first structures to be preserved; they may be preserved in three dimensions, having been solidified before they could be flattened. As these structures are unique to predatory and scavenging arthropods, this form of preservation is limited to – and diagnostic of – such creatures.
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This first pulse was the larger of the two and caused the extinction of most of the marine animal species that existed in the shallow and deep oceans. The second phase of extinction was associated with strong sea level rise, and due to the atmospheric conditions, namely oxygen levels being at or below 50% of present- day levels, high levels of anoxic waters would have been common. This anoxia would have killed off many of the survivors of the first extinction pulse. In all the extinction event of the Late Ordovician saw a loss of 85% of marine animal species and 26% of animal families.
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The differential diagnosis of PNES firstly involves ruling out epilepsy as the cause of the seizure episodes, along with other organic causes of non-epileptic seizures, including syncope, migraine, vertigo, anoxia, hypoglycemia, and stroke. However, between 5-20% of people with PNES also have epilepsy. Frontal lobe seizures can be mistaken for PNES, though these tend to have shorter duration, stereotyped patterns of movements and occurrence during sleep. Next, an exclusion of factitious disorder (a subconscious somatic symptom disorder, where seizures are caused by psychological reasons) and malingering (simulating seizures intentionally for conscious personal gain – such as monetary compensation or avoidance of criminal punishment) is conducted.
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Without protection in anoxic sediments, amber would gradually disintegrate; it is never found buried in fossil soils. Various factors contribute greatly to what kinds of insects become preserved and how well, if indeed at all, including lake depth, temperature, and alkalinity; type of sediments; whether the lake was surrounded by forest or vast and featureless salt pans; and if it was choked in anoxia or highly oxygenated. There are some major exceptions to the lacustrine theme of fossil insects, the most famous being the Late Jurassic limestones from Solnhofen and Eichstätt, Germany, which are marine. These deposits are famous for pterosaurs and the earliest bird, Archaeopteryx.
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Pcrit is nevertheless closely tied to a fish's hypoxia tolerance, in part because some fish prioritize their use of aerobic metabolism over anaerobic metabolism and metabolic suppression. It therefore remains a widely used hypoxia tolerance metric. A fish's hypoxia tolerance can also be represented as the amount of time it can spend at a particular hypoxic PO2 before it loses dorsal-ventral equilibrium (called time-to-LOE), or the PO2 at which it loses equilibrium when PO2 is decreased from normoxia to anoxia at some set rate (called PO2-of- LOE). A higher time-to-LOE value or a lower PO2-of-LOE value therefore imply enhanced hypoxia tolerances.
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Klüver–Bucy syndrome was first documented among certain humans who had experienced temporal lobectomy in 1955 by H. Terzian and G.D. Ore. It was first noted in a human with meningoencephalitis in 1975 by Marlowe et al. Klüver–Bucy syndrome can manifest after either of these (lobectomies can be medically required by such reasons as accidents or tumors), but may also appear in humans with acute herpes simplex encephalitis or following a stroke. Other conditions may also contribute to a diagnosis of Klüver–Bucy syndrome, including Pick's disease, Alzheimer's disease, ischemia, anoxia, progressive subcortical gliosis, Rett syndrome, porphyria and carbon monoxide poisoning, among others.
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There are severe reproductive costs as a result of the female spotted hyena's pseudo- penis. Nearly all female spotted hyena’s first-born cubs are stillborn, as the placenta is not long enough for the extended penile birth canal. In addition, the first birthing process is time-consuming, as it requires the meatus of the pseudo-penis to tear, allowing the fetus to pass through; as a result, the first-born often die of anoxia. Female spider monkeys have a clitoris that is referred to as a pseudo-penis because it is especially developed and has a shallow perineal groove that retains and distributes urine droplets as the female moves around.
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Studies were done measuring the nitrate uptake and nitrate reductase activity in anoxic conditions to see if there was a difference in activity level and tolerance to anoxia. These studies found that nitrate reductase, in anoxic conditions improves the plants tolerance to being less aerated. This increased activity of nitrate reductase was also related to an increase in nitrite release in the roots. The results of this study showed that the dramatic increase in nitrate reductase in anoxic conditions can be directly attributed to the anoxic conditions inducing the dissociation of 14-3-3 protein from NR and the dephosphorylation of the nitrate reductase.
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Reservoirs often serve as a catchment basin for organic matter such as vegetation, and waste transferred into the river via rainwater runoff. Initially, this organic matter provides a nutrient source; however, as it continues to accumulate and begins to decompose, the respiration of this organic matter can quickly deplete oxygen levels leading to anoxia. Under anoxic conditions, the large amount of organic matter are further broken down through anaerobic respiration and methanogenesis into carbon dioxide (CO2) and methane (CH4). These decomposition processes can occur rapidly after flooding, when large amount of fresh organic matter are transported into the river, and as a result methane and carbon dioxide release can be large.
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The effect of this warm water propagates through the ocean, and reduces the amount of that the oceans can hold in solution, which makes the oceans release large quantities of into the atmosphere in a geologically short time (tens or thousands of years). The warm waters also initiate the release of clathrates, which further increases atmospheric temperature and basin anoxia. Similar positive feedbacks operate during cold-pole episodes, amplifying their cooling effects. The periods with cold poles are termed "P-episodes" (short for primo), and are characterised by bioturbated deep oceans, a humid equator and higher weathering rates, and terminated by extinction events – for example, the Ireviken and Lau events.
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Deprivation of oxygen in the presence of carbon dioxide creates panic and a sense of suffocation (the hypercapnic alarm response), and struggling even when unconscious, whereas anoxia in the presence of an inert gas, like nitrogen, helium or argon, does not. Close contact with an enclosed inert gas is lethal, but released into the open air, it quickly disperses, and is safe for others. It is neither flammable nor explosive. Humphry's book describes close contact with the gas achieved by enclosing the head in a strong, clear plastic bag, secured around the neck, with the inert gas fed into the bag by plastic tubing.
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Both patient groups were further separated into those that suffered from traumatic brain injury and those that suffered from non- traumatic brain injures (anoxia, tumor, hydrocephalus, infection). The patients were assessed multiple times over a period of 12 months post injury using the Disability Rating Scale (DRS) which ranges from a score of 30=dead to 0=no disabilities. The results show that the DRS scores for the MCS subgroups showed the most improvement and predicted the most favorable outcomes 12 months post injury. Amongst those diagnosed with MCS, DRS scores were significantly lower for those with non-traumatic brain injuries in comparison to the vegetative state patients with traumatic brain injury.
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Also called live chilling, this method involves putting fish in baths of ice water, where they chill and eventually die of anoxia. Because chilling slows metabolic rate and oxygen needs, it may prolong the duration until death in some instances, with some cold adapted species taking more than an hour to die. On these grounds, the Farm Animal Welfare Council's 1996 report on farmed-fish welfare stated: "The cooling of live trout on ice after they have been removed from water should be prohibited." In contrast, later research suggested that for warm Mediterranean species such as sea bream and sea bass, the method might at least be preferable to air asphyxiation, with fish showing lower levels of stress indicators.
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During 1918–19 he was attached to the Australian Flying Corps medical boards in London, concurrently initiating research into problems related to anoxia under Henry Dale. Dale was doubtless Kellaway's lifelong scientific mentor and patron, and he is likely to have encouraged Kellaway to apply for the Royal Society's inaugural Foulerton Studentship in 1919. This Kellaway did after his repatriation to Australia, spending the second half of 1919 as acting professor of physiology at Adelaide University. Winning the Foulerton Studentship allowed Kellaway to return to Britain, spending the years 1920–23 working with Dale at the National Institute for Medical Research, with Charles Sherrington at Oxford University, and with Thomas Elliott at the University College Hospital in London.
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This value of 61% in the US is an average of 57% black male SIDS, 62.2% white male SIDS and 59.4% for all other races combined. Note that when multiracial parentage is involved, infant race is arbitrarily assigned to one category or the other; most often it is chosen by the mother. The X-linkage hypothesis for SIDS and the male excess in infant mortality have shown that the 50% male excess could be related to a dominant X-linked allele, occurring with a frequency of that is protective of transient cerebral anoxia. An unprotected male would occur with a frequency of and an unprotected female would occur with a frequency of .
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Acidification may also have played a role in the extinction of the calcifying foraminifera, and the higher temperatures would have increased metabolic rates, thus demanding a higher food supply. Such a higher food supply might not have materialized because warming and increased ocean stratification might have led to declining productivity and/or increased remineralization of organic matter in the water column, before it reached the benthic foraminifera on the sea floor (). The only factor global in extent was an increase in temperature. Regional extinctions in the North Atlantic can be attributed to increased deep-sea anoxia, which could be due to the slowdown of overturning ocean currents, or the release and rapid oxidation of large amounts of methane.
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The secretome of (mesenchymal) Stem Cells has positive effects on reestablishing the intra-articular homeostasis and stimulating regeneration by different growth factors, cytokines and miRNA that are contained within the extracellular vesicles of the secretome. As a consequence, efforts have been made to synthesize specific stem cell secretomes efficiently, in vitro. In general, stem cells become activated and produce higher amounts of secretome in response to external stress (for example, by damaged tissues in vivo). As such, the main preconditioning mechanism to induce secretome (extracellular vesicles) production are stress-inducing methods, most prominently anoxia and hypoxia, but also pharmacological, physical or cytokine-related methods that force the cells to produce secretome in vitro.
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1984, First Edition. ()Glasgow Herald 4 May 1967, article 'Air Vice-Marshal dies at 53' Royal Aeronautical Society, named lectures - Stewart Lecture. Retrieved 2011-01-18 The IAM obtained a decompression chamber (moved from the Physiological Laboratory) in 1945, and this was supplemented by a climatic chamber in 1952, and human centrifuge in 1955 (the latter facility is still in operation and was designated a Grade 2 Listed Building in August 2007). Additionally, the Institute was responsible for a number of mobile decompression chambers and the training of operators for chambers deployed at certain RAF operational stations with the object of familiarising flying personnel with the effects of anoxia at operational altitudes.
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Many hypoxic environments never reach the level of anoxia and most fish are able to cope with this stress using different physiological and behavioural strategies. Fish that use air breathing organs (ABO) tend to live in environments with highly variable oxygen content and rely on aerial respiration during times when there is not enough oxygen to support water-breathing. Though all teleosts have some form of swim bladder, many of them are not capable of breathing air, and they rely on aquatic surface respiration as a supply of more oxygenated water at the surface of the water. However, many species of teleost fish are obligate water breathers and do not display either of these surface respiratory behaviours.
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Donald Canfield detected records of the first significant quantities of atmospheric oxygen just before the first Ediacaran fossils appeared – and the presence of atmospheric oxygen was soon heralded as a possible trigger for the Ediacaran radiation. Oxygen seems to have accumulated in two pulses; the rise of small, sessile (stationary) organisms seems to correlate with an early oxygenation event, with larger and mobile organisms appearing around the second pulse of oxygenation. However, the assumptions underlying the reconstruction of atmospheric composition have attracted some criticism, with widespread anoxia having little effect on life where it occurs in the Early Cambrian and the Cretaceous. Periods of intense cold have also been suggested as a barrier to the evolution of multicellular life.
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There is debate over the dangers of choke- outs. After 4 to 6 minutes of sustained cerebral anoxia, permanent brain damage will begin to occur, but the long-term effects of a controlled choke- out for less than 4 minutes (as most are applied for mere seconds and released when unconsciousness is achieved) are disputed. There is always risk of short- term memory loss, hemorrhage and harm to the retina, concussions from falling when unconscious, stroke, seizures, permanent brain damage, coma, and even death. Some argue that when pressure is applied to the carotid artery, the baroreceptors send a signal to the brain via the glossopharyngeal nerveCONSTANTINOS H. DAVOS, LEWIS CERI DAVIES, MASSIMO PIEPOLI.
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In Canada, hanging is the most common method of suicide, and in the U.S., hanging is the second most common method, after self-inflicted gunshot wounds. In the United Kingdom, where firearms are less easily available, in 2001 hanging was the most common method among men and the second most commonplace among women (after poisoning). Those who survive a suicide- via-hanging attempt, whether due to breakage of the cord or ligature point, or being discovered and cut down, face a range of serious injuries, including cerebral anoxia (which can lead to permanent brain damage), laryngeal fracture, cervical spine fracture (which may cause paralysis), tracheal fracture, pharyngeal laceration, and carotid artery injury.
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Large phreatomagmatic eruptions occurred when the Emeishan Traps first started to erupt, leading to the extinction of fusulinacean foraminifera and calcareous algae. In the absence of radiometric ages directly constraining the extinction horizons themselves in the marine sections, most recent studies refrain from placing a number its age but based on extrapolations from the Permian timescale an age of approximately 260–262 Ma has been estimated;Bond, D.P.G., Wignall, P.B., Joachimski, M.M., Sun, Y., Savov, I., Grasby, S.E., Beauchamp, B. and Blomeier, D.P. 2015. An abrupt extinction in the Middle Permian (Capitanian) of the Boreal Realm (Spitsbergen) and its link to anoxia and acidification. Geological Society of America Bulletin, 127 (9-10): 1411-1421.
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The Proterozoic is the transition era between anoxic and oxygenated oceans. The classic model is that the end of the Banded iron formations (BIFs) was due to the injection of oxygen into the deep ocean, an approximately 0.6 billion year lag behind the Great Oxygenation Event. Canfield, however, argued that anoxia lasted much longer, and the end of the banded iron formations was due to the introduction of sulfide. Supporting Canfield's original hypothesis, 1.84 billion year old sedimentary records have been found in the Animike group in Canada that exhibit close to full pyritization on top of the last of the banded iron formations, showing evidence of a transition to euxinic conditions in that basin.
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The degree of pyritization and the δ34S were both high, supporting the presence of anoxia and sulfide, as well as the depletion of sulfate. A different study found biomarkers for green sulfur bacteria and purple sulfur bacteria in the same area, providing further evidence for the reduction of sulfate to hydrogen sulfide. Molybdenum isotopes have been used to examine the distribution of euxinia in the Proterozoic eon, and suggest that perhaps euxinia was not as widespread as Canfield initially postulated. Bottom waters may have been more widely suboxic than anoxic, and there could have been negative feedback between euxinia and the high levels of surface primary production needed to sustain euxinic conditions.
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By the mid-20th century, the tracheotomy as well as endoscopy and non-surgical tracheal intubation had evolved from rarely employed procedures to becoming essential components of the practices of anesthesiology, critical care medicine, emergency medicine, and laryngology. Tracheal intubation can be associated with complications such as broken teeth or lacerations of the tissues of the upper airway. It can also be associated with potentially fatal complications such as pulmonary aspiration of stomach contents which can result in a severe and sometimes fatal chemical aspiration pneumonitis, or unrecognized intubation of the esophagus which can lead to potentially fatal anoxia. Because of this, the potential for difficulty or complications due to the presence of unusual airway anatomy or other uncontrolled variables is carefully evaluated before undertaking tracheal intubation.
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The ideal relative humidity for wooden objects is 50%; museums aim to keep the environment’s relative humidity within a few percentage points of this target; typically with no more than 10% fluctuation within a 24 hour period. A stable temperature is also considered preferable, as any fluctuations directly affects relative humidity. Conservators use an Integrated Pest Management policy to reduce the threats of pests and vermin to collections, pest eradication processes are carefully selected to take into account the sacred nature of the shrines. For some religious groups, certain pest control methods such as freezing and anoxia are considered just as deadly to the sacred nature of the object as to pests; therefore, they should not be undertaken if the appropriate religious community forbids them.
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In non-bisphosphonate cases of ONJ, it is mainly the cancellous portion of the bone and its marrow content that are involved in the disease process. The first stage is an oedema of the bone marrow initiated by a bone infarct, which is itself modulated by numerous causes, leading to myelofibrosis as a result of hypoxia and gradual loss of bone density characteristic of ischaemic osteoporosis. Further deterioration can be triggered by additional bone infarcts leading to anoxia and localized areas of osteonecrosis within the osteoporotic cancellous bone. Secondary events such as dental infection, injection of local anaesthetics with vasoconstrictors, such as epinephrine, and trauma can add further complications to the disease process and chronic non-pus forming bone infection osteomyelitis can also be associated with ONJ.
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Though the two alkyl moieties readily support growth of certain microorganisms, the atrazine ring is a poor energy source due to the oxidized state of ring carbon. In fact, the most common pathway for atrazine degradation involves the intermediate, cyanuric acid, in which carbon is fully oxidized, thus the ring is primarily a nitrogen source for aerobic microorganisms. Atrazine may be catabolized as a carbon and nitrogen source in reducing environments, and some aerobic atrazine degraders have been shown to use the compound for growth under anoxia in the presence of nitrate as an electron acceptor, a process referred to as a denitrification. When atrazine is used as a nitrogen source for bacterial growth, degradation may be regulated by the presence of alternative sources of nitrogen.
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The relative delay in the recovery of benthic organisms has been attributed to widespread anoxia, but high abundances of benthic species contradict this explanation. More recent work suggests that the pace of recovery was intrinsically driven by the intensity of competition among species, which drives rates of niche differentiation and speciation. Accordingly, low levels of interspecific competition in seafloor communities that are dominated by primary consumers correspond to slow rates of diversification and high levels of interspecific competition among nektonic secondary and tertiary consumers to high diversification rates. Whereas most marine communities were fully recovered by the Middle Triassic, global marine diversity reached pre-extinction values no earlier than the Middle Jurassic, approximately 75 million years after the extinction event.
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These akinetes can persist in sediment for long periods of time, and are able to germinate once water temperatures rise to the appropriate level. The bacteria prefers temperatures ranging from 25–30 °C, light intensity of 80–121 μmol m-2 s-1, and a max salinity concentration of 4 g L-1 NaCl. The levels of the bacteria typically stay relatively low throughout the summer, however it can be associated with very high concentrations under certain conditions. These conditions include: low flow; low water level; low nitrogen to phosphorus ratio; high water temperature; stable thermal stratification; increased retention time; high pH; high sulfate concentration; anoxia in at least some strata; high turbidity; high incident irradiation; and low macrophyte biomass.
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Evidence for anoxia include the high amounts of organic matter, lack of evidence for benthic organisms (fossils or trace fossils), and enrichment in the redox proxies molybdenum and vanadium. After the significant drop in sea level (marine regression) associated with deposition of the Woodbine during the Early Cenomanian, the sea level began to rise (marine transgression), allowing for the deposition of Lower Eagle Ford organic-rich marls in South Texas and limestones of the Terrell Member of the Boquillas Formation in West Texas starting at about 96 million years ago. Gardner, R. D., M. C. Pope, M. P. Wehner, and A. D. Donovan (2013) “Comparative stratigraphy of the Eagle Ford Group in Lozier Canyon and Antonio Creek, Terrell County, Texas”: GCAGS Journal, v. 2, p. 42-52.
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These include the effects of watershed development on coastal bays and near-shore ocean waters, wastewater discharges, habitat loss and alteration of aquatic systems, nutrient enrichment and eutrophication, hypoxia and anoxia, organic pollution, chemical contaminants, climate change, sea-level rise, overfishing, invasive species, watercraft effects, dredging and dredged material disposal, freshwater diversions, calefaction of estuarine waters, and entrainment and impingement of electric generating stations. He has also examined the effects of construction and operation of industrial facilities, maintenance of shorelines and waterways, and human use of coastal space and aquatic systems. As the co- chair of the Coastal Climate Change Group in the Climate and Environmental Change Initiative, Kennish is heavily involved in the study of long-term climate change impacts on the New Jersey coast.
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In other species, the coalescence of the gill openings is less complete, and in Bdellostoma, each pouch opens separately to the outside like in lampreys. The unidirectional water flow passing the gills is produced by rolling and unrolling velar folds located inside a chamber developed from the nasohypophyseal tract, and is operated by a complex set of muscles inserting into cartilages of the neurocranium, assisted by peristaltic contractions of the gill pouches and their ducts. Hagfish also have a well- developed dermal capillary network that supplies the skin with oxygen when the animal is buried in anoxic mud, as well as a high tolerance for both hypoxia and anoxia, with a well developed anaerobic metabolism. The skin has also been suggested to be capable of cutaneous respiration.
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The bay approached sterile conditions at the peak of pollution and algal bloom-induced anoxia. Environmental actions from the 1970s to present have helped slowly bring back sea life, but current conditions pale to the wealth of marine resources of the past; certain species of fish and birds continue to decline, and the introduction of tenacious exotic species from around the world contribute to their decline. As a sign of optimism though, oysters are beginning to naturally reappear in the Hudson River after having vanished completely about the time of World War II. Regional industrial overdevelopment and other pollution factors have raised PCB levels in the fish catch and prompted government recommendations against its routine consumption. The bay is crossed by a dredged channel allowing commercial ships to enter the Arthur Kill.
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In healthy bone these cells are constantly replaced by differentiation of bone marrow mesenchymal stem cells (MSC). However, in both non-traumatic osteonecrosis and alcohol-induced osteonecrosis of the femoral head, a decrease in the differentiation ability of mesenchymal stem into bone cells has been demonstrated, and altered osteoblastic function plays a role in ON of the femoral head. If these results are extrapolated to ONJ the altered differentiation potential of bone marrow mesenchymal stem cells (MSC) combined with the altered osteoblastic activity and premature death of existing bone cells would explain the failed attempts at repair seen in ischaemic-damaged cancellous bone tissue in ONJ. The rapidity with which premature cell death can occur depends on the cell type and the degree and duration of the anoxia.
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It was revealed that during hypoxia phosphoinositide signaling is activated in endothelial cells, which leads to the activation of protein kinase C triggering the endocytosis of b-adrenergic receptors, which in turn leads to the cells developing insensitivity to catecholamines. During deep hypoxia and anoxia ATF- and ADF- hydrolyzing ferments disappear from the surface of endothelial cells, which leads to enhanced aggregation of platelets and endothelium hormone secretion. In the 90s, a group directed by V. A. Tkachuk published a number of papers on stretching receptors’ involvement in specific regulation of gene expression in vessel cells. It was demonstrated that when a single smooth muscle cell is rhythmically stretched, it shows increased expression of a number of genes (caldesmon, calpomin, α-actine, smooth muscle myosin), along with increased proliferation ability.
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Because air clathrates from melting glacial ice are the primary source of oxygen to subglacial lake waters, the concentration of oxygen generally decreases with depth in the water column if turnover is slow. Oxic or slightly suboxic waters often reside near the glacier-lake interface, while anoxia dominates in the lake interior and sediments due to respiration by microbes. In some subglacial lakes, microbial respiration may consume all of the oxygen in the lake, creating an entirely anoxic environment until new oxygen-rich water flows in from connected subglacial environments. The addition of oxygen from ice melt and the consumption of oxygen by microbes may create redox gradients in the subglacial lake water column, with aerobic microbial mediated processes like nitrification occurring in the upper waters and anaerobic processes occurring in the anoxic bottom waters.
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Interpreting the sulfur isotope composition of CAS can be complex. As discussed above, if seawater sulfate at a particular horizon in the geologic record gets heavier (i.e. more enriched in 34S relative to seawater sulfate before it) that could mean that the 34S-depleted products of sulfur-reducing reactions are being buried as sulfide minerals and removed from the oceans, possibly because of an instance of ocean anoxia or an increase in dissimilatory sulfate reduction by marine microorganisms. But it could also mean that the CAS measured at that particular horizon was derived not from seawater sulfate at the time of carbonate deposition, but from fluids moving through the sediment or porous rock from a later time, in which sulfate could have been enriched by processes in a more oxidizing world.
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The health management system’s idea of a top down neural control of the body is also found in the idea that a central governor regulates muscle fatigue to protect the body from the harmful effects (such as anoxia and hyperglycemia) of over prolonged exercise. The idea of a fatigue governor was first proposed in 1924 by the 1922 Nobel Prize winner Archibald Hill, and more recently, on the basis of modern research, by Tim Noakes. Like with the health management system, the central governor shares the idea that much of what is attributed to low level feedback homeostatic regulation is, in fact, due to top down control by the brain. The advantage of this top down management is that the brain can enhance such regulation by allowing it to be modified by information.
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Adriatic sturgeons are slow-growing, long-lived fish, wild males are sexually mature at 7–11 years old (about 80 cm long), females at 12–14 years old (at least 1 m long) and ovulate every 2–4 years. During spring months mature fish migrate to the upper part of the rivers, then they lay eggs from April to June in deep and oxygenated waters, on gravelly substrates at a depth of 2–10 m, with a current velocity of 0.8 m/s at least. Water turbulence is very important for the reproductive success of sturgeons, since it avoids egg stress, aggregation of the eggs, anoxia, parasites, and predators. The eggs adhere at the substrate and hatch after about a week, fry are about 8–10 mm long with pelagic attitude like other sturgeons, then after ten days they begin to be demersal.
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" Jason Braithwaite, a senior lecturer in Cognitive Neuroscience in the Behavioural Brain Sciences Centre, University of Birmingham, issued an in- depth analysis and critique of Lommel's prospective study published in the medical journal The Lancet, concluding that while Lommel's et al. study makes a useful contribution, it contains several factual and logical errors. Among these errors are Lommel's misunderstandings and misinterpretations of the dying-brain hypothesis, misunderstandings over the role of anoxia, misplaced confidence in EEG measurements (a flat electroencephalogram (EEG) reading is not evidence of total brain inactivity), etc. Jason concluded with, "it is difficult to see what one could learn from the paranormal survivalist position which sets out assuming the truth of that which it seeks to establish, makes additional and unnecessary assumptions, misrepresents the current state of knowledge from mainstream science, and appears less than comprehensive in its analysis of the available facts.
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Temperatures throughout the Jurassic and Cretaceous are generally thought to have been relatively warm, and consequently dissolved oxygen levels in the ocean were lower than today – making anoxia easier to achieve. However, more specific conditions are required to explain the short-period (less than a million years) oceanic anoxic events. Two hypotheses, and variations upon them, have proved most durable. One hypothesis suggests that the anomalous accumulation of organic matter relates to its enhanced preservation under restricted and poorly oxygenated conditions, which themselves were a function of the particular geometry of the ocean basin: such a hypothesis, although readily applicable to the young and relatively narrow Cretaceous Atlantic (which could be likened to a large-scale Black Sea, only poorly connected to the World Ocean), fails to explain the occurrence of coeval black shales on open-ocean Pacific plateaus and shelf seas around the world.
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Davis breathing apparatus tested at the submarine escape test tank at HMS Dolphin, Gosport, 14 December 1942 The DSEA rig chiefly addressed the problem of anoxia threatening a person ascending through water, by providing oxygen; and the associated risk of lung over-pressure injury as underwater pressure reduces with reducing depth, which it addressed by managing oxygen pressures. It also provided assistance with buoyancy, both in the ascent and after reaching the surface. The risk of decompression illness due to ascending too fast could be addressed by associated equipment; any other escape requirements, such as means of summoning help once the surface was reached, were not considered. The apparatus itself comprises a rubber breathing/buoyancy bag, which contains a canister of barium hydroxide to scrub exhaled CO2 and, in a pocket at the lower end of the bag, a steel pressure cylinder holding approximately 56 litres of oxygen at a pressure of 120 bar.
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Examples of common harmful effects of HABs include: #the production of neurotoxins which cause mass mortalities in fish, seabirds, sea turtles, and marine mammals #human illness or death via consumption of seafood contaminated by toxic algae #mechanical damage to other organisms, such as disruption of epithelial gill tissues in fish, resulting in asphyxiation #oxygen depletion of the water column (hypoxia or anoxia) from cellular respiration and bacterial degradation Due to their negative economic and health impacts, HABs are often carefully monitored. HABs occur in many regions of the world, and in the United States are recurring phenomena in multiple geographical regions. The Gulf of Maine frequently experiences blooms of the dinoflagellate Alexandrium fundyense, an organism that produces saxitoxin, the neurotoxin responsible for paralytic shellfish poisoning. The well-known "Florida red tide" that occurs in the Gulf of Mexico is a HAB caused by Karenia brevis, another dinoflagellate which produces brevetoxin, the neurotoxin responsible for neurotoxic shellfish poisoning.
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The main threat that Adriatic sturgeons face is damming, which involves the fragmentation of the habitat and prevents trophic and spawning migrations. The building of a dam severely modifies the river habitat upstream and downstream for many kilometers: upstream the current can be very slow, with water turbidity, water stratification and hypoxia or even anoxia on the bottom; downstream the nature of the substrate can change and water can be warmer and hypoxic, so the reproductive success of sturgeons can be very low or null and the metabolism of juveniles can be very stressed (above 23–25 °C for A. naccarii). Before the building of some fish ladders on the main watercourses, most (if any) of the traditional spawning areas of the Po basin were not available to Adriatic sturgeons for decades, and this involved the collapse of wild populations of A. naccarii, as well as of other species of sturgeon (A. sturio, Huso huso) in the Adriatic sea.
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Possible causes supported by strong evidence appear to describe a sequence of catastrophes, each worse than the last: the Siberian Traps eruptions were bad enough alone, but because they occurred near coal beds and the continental shelf, they also triggered very large releases of carbon dioxide and methane. The resultant global warming may have caused perhaps the most severe anoxic event in the oceans' history: according to this theory, the oceans became so anoxic, anaerobic sulfur-reducing organisms dominated the chemistry of the oceans and caused massive emissions of toxic hydrogen sulfide. However, there may be some weak links in this chain of events: the changes in the 13C/12C ratio expected to result from a massive release of methane do not match the patterns seen throughout the early Triassic; and the types of oceanic thermohaline circulation that may have existed at the end of the Permian are not likely to have supported deep-sea anoxia.
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Cyanobacterial harmful algae blooms (also known as blue-green algae) have flourished in the bay due to a variety of environmental stressors: Agricultural fertilizer run- off increases nutrients in the delicately balanced environment and the excess increases the bacteria's rate of growth; The newly hyper-saline environment provides an ideal breeding ground for cyanobacteria; Rafts of dead seagrass floating on the surface of the water as well as decaying on the bay bottom leads to anoxia and in turn, algal blooms. Blue-green algae causes numerous severe health consequences for the marine ecosystem as well surrounding human populations. Blooms result in reduced dissolved oxygen concentrations, alterations in aquatic food webs, algal scum lining the shores, the production of compounds that cause distasteful drinking water and fish flesh, and the production of toxins severe enough to poison aquatic as well as terrestrial organisms. Blooms have been reported throughout the continental United States, and resulting cyanotoxins have been associated with human and animal illness and death in at least 43 states.
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