Sentences with phrase «oxygen concentrations of»

To achieve their protective effects, Yu and Wei are using oxygen concentrations of 0.5 %.

«The resulting six-fold increase in oxygen would have significantly influenced biogeochemical cycling of [oxidation] sensitive elements such as [iron] and [sulfur] and ultimately increased the oxygen concentration of the atmosphere,» the team writes in a paper published online today by the journal Science.

Not exact matches

Landon was diagnosed with hypernatremic dehydration (a high concentration of sodium in the blood), cardiac arrest from hypovolemic shock (a condition where the liquid portion of the blood is dangerously low), and hypoxic - ischemic encephalopathy (a brain injury caused by oxygen deprivation).

What happens is that a too high concentration of nitrates can prevent oxygen from being carried properly in your baby's blood.

High nitrate concentrations can be particularly dangerous for babies under six months, since nitrate interferes with the ability of blood to carry oxygen.

This expanse of low - oxygen, or hypoxic, waters is produced by an overgrowth of algae caused by high nutrient concentrations.

Notably, Terada and his colleagues say, previous studies have shown that the overall proportions of oxygen isotopes in the ozone layer also are skewed toward above - average concentrations of oxygen - 17 and oxygen - 18.

Another strategy is to make alternative versions of terminal oxidases, enzymes in the membrane that transfer electrons to oxygen, which use oxygen more efficiently or are better at scavenging oxygen when its concentration is low.

Examining the distribution patterns of microfossils, Shen's Harvard colleagues have discovered that the marine eukaryotic algae of 1.5 billion years ago occupied only the ocean shallows and not the deeper basins, indicating a smaller oxygen concentration in the atmosphere than exists today.

This technique provides a measure of blood oxygen concentration in surface blood vessels, indicative of activity in the brain's outer layers, using a set of wearable probes in a cap that is placed on the head.

Near - freezing water, lack of sunlight, and low oxygen concentrations discourage the growth of bacteria and other organisms that can break down debris.

This includes places like parts of the eastern Pacific Ocean where small animals like nematodes and specially adapted fish live on the fringes of habitability, subsisting in waters where oxygen concentrations can be only about 1 % of normal surface water levels.

Because oxygen is critical to many forms of life and geochemical processes, numerous models and indirect proxies for the oxygen content in the atmosphere have been developed over the years, but there was no consensus on whether oxygen concentrations were rising, falling or flat during the past million years (and before fossil fuel burning).

Globular clusters contain far lower concentrations of the planet - forming heavy elements — such as carbon, oxygen, and iron — than do our sun and nearby stars, leading some to suspect that it might be difficult for planets to form there.

The animal's greatest advantage seems to lie in the ability of its haemocyanin to take up oxygen from water passing over its gills even when the concentration of oxygen is very low.

Curiously, the decline in atmospheric oxygen over the past 800,000 years was not accompanied by any significant increase in the average amount of carbon dioxide in the atmosphere, though carbon dioxide concentrations do vary over individual ice age cycles.

The separation into two chambers means there are two separate flue gas streams to deal with too: air with a reduced concentration of oxygen is discharged from one chamber, water vapour and CO2 from the other.

In places where sea - floor oxygen levels are a bit higher — about 0.5 — 3 % of concentrations at the sea surface — animals are more abundant but their food webs remain limited: the animals still feed on microbes rather than on each other.

They charted how fluctuating oxygen concentrations correlated with the emergence of new animals as seen in the fossil record and from genetic data.

For each degree of ocean warming, oxygen concentration goes down by 2 percent.

These proxies seemed to indicate that oxygen concentrations in the oceans rose in several steps, approaching today's sea - surface concentrations at the start of the Cambrian, around 541 million years ago — just before more - modern animals suddenly appeared and diversified.

The increasing concentration of oxygen in the atmosphere eventually overwhelmed the control on oxygen and meant it could finally rise to the levels we are used to today.

Mimicking this behaviour of biological tissues in nature, the research team comprising CMU scientists Changjin Huang, David Quinn, K. Jimmy Hsia and NTU President - designate Prof Subra Suresh, showed that through manipulation of oxygen concentration, one can pattern and control the growth rate of hydrogels to create the desired complex 3D shapes.

Depending on the concentration of oxygen atoms, the chain - like slabs were two, three, or four layers thick, sometimes varying within the same material.

By watching a capsule pass through the gut with an ultrasound, the researchers found that oxygen concentrations varied in different regions of the gut, for example between the stomach and the small intestine.

«Concentrations of oil in this deep plume are so low that we don't see oxygen depletion,» he explains.

Other specific conditions, such as the concentration of dissolved oxygen in the pore water of the filter body, reduce the ability of pathogens to survive in planted soil filters.

As a result, oxygen saturation at depth dropped from an average of 67 percent to 59 percent while microbial cell concentrations doubled to 5,510 cells per milliliter compared with just 2,730 cells per milliliter outside the plume.

Because diffusion becomes less efficient as the tubes get longer, the atmospheric concentration of oxygen is a powerful constraint on body size, especially for active insects that fly.

They also used satellite precipitation data to «backsolve» the brine's origins using sodium concentrations, oxygen and hydrogen isotopes, as the isotopic composition of water reflects the condensation temperature and precipitation rate over time.

The normal job of the carotid body, nestled in the carotid artery, is to signal your brain to step up your breathing if your blood oxygen concentrations drop too low.

Results of the study, which the researchers report online today in the Proceedings of the National Academy of Sciences, show that for the first 170 million years or so of flying - insect evolution, wing length grew and shrank in step with variations in average oxygen concentration.

Previous studies have shown that they have lower oxygen concentrations in the blood of their arteries (ScienceNOW, 16 September 2004).

To isolate the effects of oxygen concentration, researchers from the University of Colorado compared the rate of SIDS in infants living at high altitudes, where the air is thin, to those living closer to sea level.

Oxygen sensors in the body measure the concentration of oxygen in the Oxygen sensors in the body measure the concentration of oxygen in the oxygen in the cells.

When a certain amount of oxygen vacancies (4 mol %) exists in the material, the proton concentration around Zr is higher than that around the rare - earth element which indicates protons with less influence from the trapping effects of the rare - earth element (Fig. 1).

This reduces the concentration of oxygen available in the tissue, which may aggravate conventional PDT.

The team used the data from charcoal in coal to propose that the development of fire systems through this interval was controlled predominantly by the elevated atmospheric oxygen concentration (p (O2)-RRB- that mass balance models predict prevailed.

The strength of the light depends on the concentration in «oxyhemoglobin» which gives the oxygen to the nerve cells working actively.

Using molecular beam epitaxy, a well - known technique from semiconductor technology, the group was able to produce RRAM structures where only the oxygen concentration was varied while all the rest of the device was identical.

The time required by the electrons to lower their energy level is directly related to the concentration of oxygen in the surrounding air.

«However, we noted that the biological approaches, which analyse the concentrations of bacteria, their DNA, and oxygen consumption, were very sensitive and provided us with a great deal of information.

In some of the samples, the team dramatically reduced the concentrations of dissolved phosphate and oxygen to simulate conditions that might exist inside equipment used to recycle urine into water on spacecraft during long - duration flights.

Their analysis showed a 3 - to 4 - ppm (parts per million) difference between the oxygen isotopic concentrations of the lunar rocks and the terrestrial basalts, but no significant difference between the lunar samples and terrestrial olivine, a common mineral in Earth's subsurface.

In fact, the completely unplanned «experiment» had left the crew gasping for breath as the oxygen concentration gradually fell from 21 per cent to less than 15 per cent, making the atmosphere as thin as at an altitude of 4000 metres.

Lyons notes that the factors controlling the rise of animals are under close scrutiny, including challenges to the long - held view that a major rise in atmospheric oxygen concentrations triggered the event.

One possible explanation the researchers found for the continued decline of oxygen concentrations is related to changes in water temperature.

Mangrove rivulus, which can live out of the water for extended periods of time (days or weeks, as long as the conditions are moist), uses its specialised jumping technique when water has low oxygen concentrations or high levels of hydrogen sulphide, or to escape predators and search for terrestrial prey such as crickets.

Analyzing sensor data and field measurements, Cohen and his students have found new clues for the algal abundance, such as declining concentrations of dissolved oxygen and the role of snails in keeping springs clear.

By triggering a process called autophagy — in which cells literally engulf their own insides — researchers from Drexel University and Yale University were able to decrease lung injury in mice that were exposed to high concentrations of oxygen.