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crucible
crucible vessel in which a substance is heated to a high temperature, as for fusing or calcining. The necessary properties of a crucible are that it maintain its mechanical strength and rigidity at high temperatures and that it not react in an undesirable way with its contents. Porcelain , iron, a...
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optician
optician filler of prescriptions for and dispenser of corrective lenses. An optician may grind lenses as instructed by the prescription of an optometrist (see optometry ) or ophthalmologist (see ophthalmology ) or transcribe the instructions for laboratory mechanics. The optician also fits and ad...
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Howard Hughes Medical Institute
Howard Hughes Medical Institute (HHMI), nonprofit medical research organization founded in 1953 by Howard Hughes and largly funded from proceeds of the 1984-85 sale of Hughes Aircraft. Headquartered in Chevy Chase, Md., it is one of the world's largest and wealthiest philanthropies. HHMI supports...
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Linus Benedict Torvalds
Linus Benedict Torvalds 1969-, Finnish computer software engineer. A member of Finland's Swedish-speaking minority, he attended the Univ. of Helsinki (M.S., 1996), where he also taught. In the early 1990s he began working on a Unix-like operating system for personal computers built with Intel micro...
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computer virus
computer virus rogue computer program , typically a short program designed to disperse copies of itself to other computers and disrupt those computers' normal operations. A computer virus usually attaches or inserts itself to or in an executable file or the boot sector (the area that contains the ...
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heroin
heroin , opiate drug synthesized from morphine (see narcotic ). Originally produced in 1874, it was thought to be not only nonaddictive but useful as a cure for respiratory illness and morphine addiction, and capable of relieving morphine withdrawal symptoms. Later it was discovered to have the...
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New Jersey
New Jersey Middle Atlantic state of the E United States. It is bordered by New York State (N and, across the Hudson R. and New York Harbor, E), the Atlantic Ocean (E), Delaware, across Delaware Bay (S), and Pennsylvania, across the Delaware R. (W).
Facts and Figures
Area, 7,836 sq mi (2...
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stem cells
stem cells unspecialized human or animal cells that can produce mature specialized body cells and at the same time replicate themselves. Embryonic stem cells are derived from a blastocyst (the blastula typical of placental mammals; see embryo ), which is very young embryo that contains 200 to 250 ...
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acetylcholine
acetylcholine , a small organic molecule liberated at nerve endings as a neurotransmitter . It is particularly important in the stimulation of muscle tissue. The transmission of an impulse to the end of the nerve causes it to release neurotransmitter molecules onto the surface of the next cell, sti...
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hypertrophy
hypertrophy , enlargement of a tissue or organ of the body resulting from an increase in the size of its cells. Such growth accompanies an increase in the functioning of the tissue. In normal physiology the growth in size of muscles (e.g., in an athlete as a result of increased exercise) and also th...
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