نتایج جستجو برای: extreme altitude
تعداد نتایج: 108126 فیلتر نتایج به سال:
THE STUDIES of Amann et al. (1, 2) provide the final evidence necessary to solve the “lactate paradox” that has haunted the exercise sciences since first described in 1936 (4) and which was the recent focus of a Point:Counterpoint debate (25, 26). In its simplest form the paradox describes the finding of lower than expected blood lactate concentrations during maximal exercise at altitude, espec...
To investigate the influence of hypoxia during the early stage of incubation on embryonic developmentand hatching events, and consequently on incidence of ascites in broiler chickens, one thousand fertile eggswere incubated in two commercial incubators. Half the eggs were incubated in a low altitude incubator untilhatched. The second half were incubated in a high altitude incubator until day 10...
Contrast sensitivity thresholds were studied over 40 d during gradual ascent to a simulated terrestrial altitude of 25,000 ft in a decompression chamber. Only ambient pressure, and thus inspired oxygen pressure, was varied, thereby eliminating many of the confounding effects of cold, dehydration, malnutrition and exhaustion, inevitably encountered on very high mountains. Contrast sensitivity th...
Bar-headed geese migrate over the Himalayas at up to 9000 m elevation, but it is unclear how they sustain the high metabolic rates needed for flight in the severe hypoxia at these altitudes. To better understand the basis for this physiological feat, we compared the flight muscle phenotype of bar-headed geese with that of low altitude birds (barnacle geese, pink-footed geese, greylag geese and ...
to investigate the influence of hypoxia during the early stage of incubation on embryonic developmentand hatching events, and consequently on incidence of ascites in broiler chickens, one thousand fertile eggswere incubated in two commercial incubators. half the eggs were incubated in a low altitude incubator untilhatched. the second half were incubated in a high altitude incubator until day 10...
“Earth summit mission 2022” is one of the landmark scientific research activities Second Tibetan Plateau Scientific Expedition and Research (STEP). This expedition firstly used advanced technology methods to detect vertical meteorological elements produce forecasts for mountain climbing. The Qomolangma exceeded an altitude over 8000 meters first time carried out a comprehensive investigation on...
Bar-headed geese are renowned for migratory flights at extremely high altitudes over the world's tallest mountains, the Himalayas, where partial pressure of oxygen is dramatically reduced while flight costs, in terms of rate of oxygen consumption, are greatly increased. Such a mismatch is paradoxical, and it is not clear why geese might fly higher than is absolutely necessary. In addition, dire...
CONTEXT Chronic hypoxia induces complex metabolic and endocrine adaptations. High-altitude (HA) exposure is a physiological model of hypoxia. OBJECTIVE To further investigate the endocrine and metabolic responses to extreme HA. METHODS We studied nine male elite climbers at sea level and at 5200 m after climbing Mt. Everest. RESULTS After 7 weeks at HA, body weight was reduced (P<0.05); r...
Antarctic ozone depletion is associated with enhanced chlorine from anthropogenic chlorofluorocarbons and heterogeneous chemistry under cold conditions. The deep Antarctic "hole" contrasts with the generally weaker depletions observed in the warmer Arctic. An unusually cold Arctic stratospheric season occurred in 2011, raising the question of how the Arctic ozone chemistry in that year compares...
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