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Altitude Acclimatization
The effects of high altitude on humans are mostly the consequences of reduced partial pressure of oxygen in the atmosphere. The medical problems that are direct consequence of high altitude are caused by the low inspired partial pressure of oxygen, which is caused by the reduced atmospheric pressure, and the constant gas fraction of oxygen in atmospheric air over the range in which humans can survive. The other major effect of altitude is due to lower ambient temperature. The oxygen saturation of hemoglobin determines the content of oxygen in blood. After the human body reaches around above sea level, the saturation of oxyhemoglobin begins to decrease rapidly. However, the human body has both short-term and long-term adaptations to altitude that allow it to partially compensate for the lack of oxygen. There is a limit to the level of adaptation; mountaineers refer to the altitudes above as the death zone, where it is generally believed that no human body can acclimatize. At ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
M Rainier
M, or m, is the thirteenth Letter (alphabet), letter of the Latin alphabet, used in the English alphabet, modern English alphabet, the alphabets of several Languages of Europe, western European languages and others worldwide. Its name in English is English alphabet#Letter names, ''em'' (pronounced ), plural ''ems''. History The letter M is derived from the Phoenician alphabet, Phoenician Mem via the Greek alphabet, Greek Mu (letter), Mu (Μ, μ). Semitic alphabets, Semitic Mem is most likely derived from a "Proto-Sinaitic script, Proto-Sinaitic" (Bronze Age) adoption of the N-water ripple (n hieroglyph), "water" ideogram in Egyptian hieroglyphs, Egyptian writing. The Egyptian sign had the acrophonic value , from the Egyptian word for "water", ''nt''; the adoption as the Semitic letter for was presumably also on acrophonic grounds, from the Semitic languages, Semitic word for "water", '':wikt:Reconstruction:Proto-Semitic/maʾ-, *mā(y)-''. Use in writing systems En ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pressure Air
Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and even by industry. Further, both spellings are often used ''within'' a particular industry or country. Industries in British English-speaking countries typically use the "gauge" spelling. is the pressure relative to the ambient pressure. Various units are used to express pressure. Some of these derive from a unit of force divided by a unit of area; the SI unit of pressure, the pascal (Pa), for example, is one newton per square metre (N/m2); similarly, the pound-force per square inch (psi, symbol lbf/in2) is the traditional unit of pressure in the imperial and US customary systems. Pressure may also be expressed in terms of standard atmospheric pressure; the unit atmosphere (atm) is equal to this pressure, and the torr is defined as of thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
USARIEM
The U.S. Army Research Institute of Environmental Medicine (USARIEM) is the U.S Army’s main institution and facility for military environmental medicine and exercise physiology research. It is located at Natick, Massachusetts, within the U.S. Army Soldier Systems Center (SSC) installation, but is a subordinate lab of the U.S. Army Medical Research and Materiel Command (USAMRMC), headquartered at Fort Detrick, Maryland, USA. Mission USARIEM’s ''Mission Statement'' mandates that the Institute: The Institute has four divisions, each relating to military human performance as it relates to the environment — Biophysical and Biomedical Modeling, Military Nutrition, Military Performance, and Thermal and Mountain Medicine. Research in the divisions focuses on three elements: the ''servicemember'' (acclimation; body size; gender; race; age; health; hydration; nutrition; fitness; and sleep status), the ''environment'' (temperature; wind; humidity; and altitude), and the ''miss ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mount Everest
Mount Everest (), known locally as Sagarmatha in Nepal and Qomolangma in Tibet, is Earth's highest mountain above sea level. It lies in the Mahalangur Himal sub-range of the Himalayas and marks part of the China–Nepal border at its summit. Its height was most recently measured in 2020 by Chinese and Nepali authorities as . Mount Everest attracts many climbers, including highly experienced mountaineers. There are two main climbing routes, one approaching the summit from the southeast in Nepal (known as the standard route) and the other from the north in Tibet. While not posing substantial technical climbing challenges on the standard route, Everest presents dangers such as altitude sickness, weather, and wind, as well as hazards from avalanches and the Khumbu Icefall. As of May 2024, 340 people have died on Everest. Over 200 bodies remain on the mountain and have not been removed due to the dangerous conditions. Climbers typically ascend only part of Mount Eve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Everest Base Camp
There are two Base camp#Shelter, base camps on Mount Everest, on opposite sides of the mountains: #South Base Camp in Nepal, South Base Camp is in Nepal at an altitude of (), while #North Base Camp in Tibet, North Base Camp is in Tibet at (). The base camps are rudimentary campsites at the base of Mount Everest that are used by mountain climbers during their ascent and descent. They are also visited by hikers. South Base Camp is used when climbing via the Mount Everest#Southeast ridge, southeast ridge, while North Base Camp is used when climbing via the Mount Everest#North ridge route, northeast ridge. Supplies are shipped to the South Base Camp by Porter (carrying), porters, and with the help of animals, usually yaks. The North Base Camp is accessed by a Everest road, paved road that branches from China National Highway 318. Climbers typically rest at base camp for several days for acclimatization, to reduce the risk of altitude sickness. South Base Camp in Nepal The Everest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Altitude
Altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum (geodesy), datum and a point or object. The exact definition and reference datum varies according to the context (e.g., aviation, geometry, geographical survey, sport, or atmospheric pressure). Although the term ''altitude'' is commonly used to mean the height above sea level of a location, in geography the term elevation is often preferred for this usage. In aviation, altitude is typically measured relative to mean sea level or above ground level to ensure safe navigation and flight operations. In geometry and geographical surveys, altitude helps create accurate topographic maps and understand the terrain's elevation. For high-altitude trekking and sports, knowing and adapting to altitude is vital for performance and safety. Higher altitudes mean reduced oxygen levels, which can lead to altitude sickness if proper acclimatization measures are not taken. Vertical distance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barometric Formula
The barometric formula is a formula used to model how the air pressure (or air density) changes with altitude. Pressure equations There are two equations for computing pressure as a function of height. The first equation is applicable to the atmospheric layers in which the temperature is assumed to vary with altitude at a non null lapse rate of L_b: P = P_ \left 1 - \frac (h - h_)\right The second equation is applicable to the atmospheric layers in which the temperature is assumed not to vary with altitude ( lapse rate is null): P = P_b \exp \left frac\right/math> where: *P_b = reference pressure *T_ = reference temperature ( K) *L_ = temperature lapse rate (K/m) in ISA *h = geopotential height at which pressure is calculated (m) *h_b = geopotential height of reference level ''b'' (meters; e.g., ''hb'' = 11 000 m) *R^* = universal gas constant: 8.3144598 J/(mol·K) *g_0 = gravitational acceleration: 9.80665 m/s2 *M = molar mass of Earth's air: 0.0289644&nb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Blood Cells
Red blood cells (RBCs), referred to as erythrocytes (, with -''cyte'' translated as 'cell' in modern usage) in academia and medical publishing, also known as red cells, erythroid cells, and rarely haematids, are the most common type of blood cell and the vertebrate's principal means of delivering oxygen () to the body tissue (biology), tissues—via blood flow through the circulatory system. Erythrocytes take up oxygen in the lungs, or in fish the gills, and release it into tissues while squeezing through the body's capillary, capillaries. The cytoplasm of a red blood cell is rich in hemoglobin (Hb), an iron-containing biomolecule that can bind oxygen and is responsible for the red color of the cells and the blood. Each human red blood cell contains approximately 270 million hemoglobin molecules. The cell membrane is composed of proteins and lipids, and this structure provides properties essential for physiological Cell (biology), cell function such as erythrocyte deformabil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Partial Pressure
In a mixture of gases, each constituent gas has a partial pressure which is the notional pressure of that constituent gas as if it alone occupied the entire volume of the original mixture at the same temperature. The total pressure of an ideal gas mixture is the sum of the partial pressures of the gases in the mixture (Dalton's Law). In respiratory physiology, the partial pressure of a dissolved gas in liquid (such as oxygen in arterial blood) is also defined as the partial pressure of that gas as it would be undissolved in gas phase yet in equilibrium with the liquid. This concept is also known as blood gas tension. In this sense, the diffusion of a gas liquid is said to be driven by differences in partial pressure (not concentration). In chemistry and thermodynamics, this concept is generalized to non-ideal gases and instead called fugacity. The partial pressure of a gas is a measure of its Thermodynamic activity, thermodynamic activity. Gases dissolve, diffuse, and react accor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmospheric Chemistry
Atmospheric chemistry is a branch of atmospheric science that studies the chemistry of the Earth's atmosphere and that of other planets. This multidisciplinary approach of research draws on environmental chemistry, physics, meteorology, computer modeling, oceanography, geology and volcanology, climatology and other disciplines to understand both natural and human-induced changes in atmospheric composition. Key areas of research include the behavior of trace gasses, the formation of pollutants, and the role of aerosols and greenhouse gasses. Through a combination of observations, laboratory experiments, and computer modeling, atmospheric chemists investigate the causes and consequences of atmospheric changes. Atmospheric composition The composition and chemistry of the Earth's atmosphere is important for several reasons, but primarily because of the interactions between the atmosphere and living organisms. Natural processes such as volcano emissions, lightning and bombardme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmosphere (unit)
The standard atmosphere (symbol: atm) is a unit of pressure defined as Pa. It is sometimes used as a ''reference pressure'' or ''standard pressure''. It is approximately equal to Earth's average atmospheric pressure at sea level. History The standard atmosphere was originally defined as the pressure exerted by a 760 mm column of mercury at and standard gravity (''g''n = ). It was used as a reference condition for physical and chemical properties, and the definition of the centigrade temperature scale set 100 °C as the boiling point of water at this pressure. In 1954, the 10th General Conference on Weights and Measures (CGPM) adopted ''standard atmosphere'' for general use and affirmed its definition of being precisely equal to dynes per square centimetre (). This defined pressure in a way that is independent of the properties of any particular substance. In addition, the CGPM noted that there had been some misapprehension that the previous definition (from the 9th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bar (unit)
The bar is a metric unit of pressure defined as 100,000 Pa (100 kPa), though not part of the International System of Units (SI). A pressure of 1 bar is slightly less than the current average atmospheric pressure on Earth at sea level (approximately 1.013 bar). By the barometric formula, 1 bar is roughly the atmospheric pressure on Earth at an altitude of 111 metres at 15 °C. The bar and the millibar were introduced by the Norwegian meteorologist Vilhelm Bjerknes, who was a founder of the modern practice of weather forecasting, with the bar defined as one megadyne per square centimetre. The SI brochure, despite previously mentioning the bar, now omits any mention of it.. The bar has been legally recognised in countries of the European Union since 2004. British Standard BS 350:2004 ''Conversion Factors for Units''. The US National Institute of Standards and Technology (NIST) deprecates its use except for "limited use in meteorology" and lists ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
