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Organisms At High Altitude
Organisms can live at high altitude, either on land, in water, or while flying. Decreased oxygen availability and decreased temperature make life at such altitudes challenging, though many species have been successfully adapted via considerable physiological changes. As opposed to short-term acclimatisation (immediate physiological response to changing environment), high-altitude adaptation means irreversible, evolved physiological responses to high-altitude environments, associated with heritable behavioural and genetic changes. Among animals, only few mammals (such as yaks, ibexes, Tibetan gazelles, vicunas, llamas, mountain goats, etc.) and certain birds are known to have completely adapted to high-altitude environments. Human populations such as some Tibetans, South Americans and Ethiopians live in the otherwise uninhabitable high mountains of the Himalayas, Andes and Ethiopian Highlands respectively. The adaptation of humans to high altitude is an example of natural se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
People Of Ethiopia
Ethiopians are the native inhabitants of Ethiopia, as well as the global diaspora of Ethiopia. Ethiopians constitute several component ethnic groups, many of which are closely related to ethnic groups in neighboring Eritrea and other parts of the Horn of Africa. The first documented use of the name "Ethiopia" from Greek name "Αἰθίοψ" (Ethiopian) was in the 4th century during the reign of Aksumite king Ezana. There were three ethnolinguistic groups in the Kingdom of Aksum; Semitic, Cushitic, and Nilo-Saharan (ancestors of the modern-day Kunama and Nara). The Kingdom of Aksum remained a geopolitically influential entity until the pillage of its capital — also named Axum — in the 10th century by Queen Gudit. Nevertheless, the core Aksumite civilization was preserved and continued into the successive Zagwe dynasty. By this time, new ethnic groups emerged – the Tigrayans and Amharas. During the Solomonic period, the latter established major political and cult ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Springtail
Springtails (Collembola) form the largest of the three lineages of modern hexapods that are no longer considered insects (the other two are the Protura and Diplura). Although the three orders are sometimes grouped together in a class called Entognatha because they have internal mouthparts, they do not appear to be any more closely related to one another than they are to all insects, which have external mouthparts. Collembolans are omnivorous, free-living organisms that prefer moist conditions. They do not directly engage in the decomposition of organic matter, but contribute to it indirectly through the fragmentation of organic matter and the control of soil microbial communities. The word ''Collembola'' is from the ancient Greek "glue" and "peg"; this name was given due to the existence of the collophore, which was previously thought to stick to surfaces to stabilize the creature. Some DNA sequence studies suggest that Collembola represent a separate evolutionary line fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Euophrys Omnisuperstes
''Euophrys omnisuperstes'' (the species name means ''standing above everything''), the Himalayan jumping spider, is a small and toxic jumping spider that lives at elevations of up to in the Himalayas, including Mount Everest, making it a candidate for the highest known permanent resident on Earth. They are found among rocky debris, feeding on tiny, stray springtails and flies. Discovery In 1924, Richard Hingston was the naturalist on the British expedition to Mount Everest. In 1925, he reported that spiders had been observed living permanently in rocky areas surrounded by snow and ice at , about above the highest plant growth. His observation that "for food they eat one another" was later described as a "self-defeating notion" and helped to support the view that the spiders had been blown there and were not permanent residents. In 1954, Lawrence W. Swan joined an American expedition to Makalu in the Himalayas, and re-discovered the jumping spiders that Hingston had observed. S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NBC News
NBC News is the news division of the American broadcast television network NBC. The division operates under NBCUniversal Television and Streaming, a division of NBCUniversal, which is, in turn, a subsidiary of Comcast. The news division's various operations report to the president of NBC News, Noah Oppenheim. The NBCUniversal News Group also comprises MSNBC, the network's 24-hour general news channel, business and consumer news channels CNBC and CNBC World, the Spanish language Noticias Telemundo and United Kingdom–based Sky News. NBC News aired the first regularly scheduled news program in American broadcast television history on February 21, 1940. The group's broadcasts are produced and aired from 30 Rockefeller Plaza, NBCUniversal's headquarters in New York City. The division presides over America's number-one-rated newscast, ''NBC Nightly News'', the world's first of its genre morning television program, ''Today'', and the longest-running television series in American ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space
Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum known as spacetime. The concept of space is considered to be of fundamental importance to an understanding of the physical universe. However, disagreement continues between philosophers over whether it is itself an entity, a relationship between entities, or part of a conceptual framework. Debates concerning the nature, essence and the mode of existence of space date back to antiquity; namely, to treatises like the ''Timaeus'' of Plato, or Socrates in his reflections on what the Greeks called ''khôra'' (i.e. "space"), or in the ''Physics'' of Aristotle (Book IV, Delta) in the definition of ''topos'' (i.e. place), or in the later "geometrical conception of place" as "spac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annual Review Of Physiology
The ''Annual Review of Physiology'' is a peer-reviewed academic journal that publishes review articles about physiology. First published in 1939 through a collaboration between the American Physiological Society and Annual Reviews, it was published solely by Annual Reviews after 1962. It covers various aspects of physiology, including cardiac, renal, respiratory, and gastrointestinal physiology, among other subfields. As of 2022, ''Journal Citation Reports'' lists the journal's 2021 impact factor as 22.163, ranking it second of 81 journal titles in the category "Physiology". History In 1938, the Annual Review of Biochemistry, Ltd and the American Physiological Society agreed to collaborate to create a new journal. As a result, the Annual Review of Biochemistry, Ltd, previously just the publisher of the journal of the same name, decided to change its name to reflect its expansion to other disciplines: Annual Reviews. The first volume of the ''Annual Review of Physiology'' was pu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Absolute Zero
Absolute zero is the lowest limit of the thermodynamic temperature scale, a state at which the enthalpy and entropy of a cooled ideal gas reach their minimum value, taken as zero kelvin. The fundamental particles of nature have minimum vibrational motion, retaining only quantum mechanical, zero-point energy-induced particle motion. The theoretical temperature is determined by extrapolating the ideal gas law; by international agreement, absolute zero is taken as −273.15 degrees on the Celsius scale (International System of Units), Note: The triple point of water is 0.01 °C, not 0 °C; thus 0 K is −2890.15 °C, not −273.16 °C. which equals −459.67 degrees on the Fahrenheit scale ( United States customary units or Imperial units). The corresponding Kelvin and Rankine temperature scales set their zero points at absolute zero by definition. It is commonly thought of as the lowest temperature possible, but it is not the lowest ''enthalpy'' state poss ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tardigrades
Tardigrades (), known colloquially as water bears or moss piglets, are a phylum of eight-legged segmented micro-animals. They were first described by the German zoologist Johann August Ephraim Goeze in 1773, who called them Kleiner Wasserbär ("little water bear"). In 1777, the Italian biologist Lazzaro Spallanzani named them Tardigrada (), which means "slow steppers". They have been found in diverse regions of Earth's biospheremountaintops, the deep sea, tropical rainforests, and the Antarctic. Tardigrades are among the most resilient animals known, with individual species able to survive extreme conditions – such as exposure to extreme temperatures, extreme pressures (both high and low), air deprivation, radiation, dehydration, and starvation – that would quickly kill most other known forms of life. Tardigrades have survived exposure to outer space. There are about 1,300 known species in the phylum Tardigrada, a part of the superphylum Ecdysozoa consisting of animals th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EPAS1
Endothelial PAS domain-containing protein 1 (EPAS1, also known as hypoxia-inducible factor-2alpha (HIF-2α)) is a protein that is encoded by the ''EPAS1'' gene in mammals. It is a type of hypoxia-inducible factor, a group of transcription factors involved in the physiological response to oxygen concentration. The gene is active under hypoxic conditions. It is also important in the development of the heart, and for maintaining the catecholamine balance required for protection of the heart. Mutation often leads to neuroendocrine tumors. However, several characterized alleles of ''EPAS1'' contribute to high-altitude adaptation in humans. One such allele, which has been inherited from Denisovan archaic hominins, is known to confer increased athletic performance in some people, and has therefore been referred to as the "super athlete gene". Function The EPAS1 gene encodes one subunit of a transcription factor involved in the induction of genes regulated by oxygen, and which is indu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergent Evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is homoplasy. The recurrent evolution of flight is a classic example, as flying insects, birds, pterosaurs, and bats have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are ''analogous'', whereas '' homologous'' structures or traits have a common origin but can have dissimilar functions. Bird, bat, and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions. The opposite of convergence is divergent evolution, where related species evolve different traits. Convergent evolution is similar to parallel evo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Selection
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Charles Darwin popularised the term "natural selection", contrasting it with selective breeding, artificial selection, which in his view is intentional, whereas natural selection is not. Genetic diversity, Variation exists within all populations of organisms. This occurs partly because random mutations arise in the genome of an individual organism, and their offspring can inherit such mutations. Throughout the lives of the individuals, their genomes interact with their environments to cause variations in traits. The environment of a genome includes the molecular biology in the Cell (biology), cell, other cells, other individuals, populations, species, as well as the abiotic environment. Because individuals with certain variants of the trait tend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
