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Trisomy 21. Down syndrome (also known by the karyotype 47,XX,+21 for females and 47,XY,+21 for males) [98] is mostly caused by a failure of the 21st chromosome to separate during egg or sperm development, known as nondisjunction. [91] As a result, a sperm or egg cell is produced with an extra copy of chromosome 21; this cell thus has 24 ...
Down feather. Down feathers lack the interlocking barbules of pennaceous feathers, making them very soft and fluffy. The down of birds is a layer of fine feathers found under the tougher exterior feathers. Very young birds are clad only in down. Powder down is a specialized type of down found only in a few groups of birds.
Genetics of Down syndrome. Down syndrome is a chromosomal abnormality characterized by the presence of an extra copy of genetic material on chromosome 21, either in whole (trisomy 21) or part (such as due to translocations). The effects of the extra copy varies greatly from individual to individual, depending on the extent of the extra copy ...
Schematic of SPDC process. Note that conservation laws are with respect to energy and momentum inside the crystal.. Spontaneous parametric down-conversion (also known as SPDC, parametric fluorescence or parametric scattering) is a nonlinear instant optical process that converts one photon of higher energy (namely, a pump photon) into a pair of photons (namely, a signal photon, and an idler ...
Watership Down is an adventure novel by English author Richard Adams, published by Rex Collings Ltd of London in 1972. Set in Hampshire in southern England, the story features a small group of rabbits .
Contents. Bottom–up and top–down design. Bottom–up and top–down are both strategies of information processing and ordering knowledge, used in a variety of fields including software, humanistic and scientific theories (see systemics), and management and organization. In practice they can be seen as a style of thinking, teaching, or ...
e. In meteorology, a downburst is a strong downward and outward gushing wind system that emanates from a point source above and blows radially, that is, in straight lines in all directions from the area of impact at surface level. It originates under deep, moist convective conditions like cumulus congestus or cumulonimbus.
The Moon Is Down. The Moon Is Down is a novel by American writer John Steinbeck. Fashioned for adaptation for the theatre and for which Steinbeck received the Norwegian King Haakon VII Freedom Cross, it was published by Viking Press in March 1942. The story tells of the military occupation of a small town in Northern Europe by the army of an ...