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servomechanism
servomechanism automatic device for the control of a large power output by means of a small power input or for maintaining correct operating conditions in a mechanism. It is a type of feedback control system. The constant speed control system of a DC motor is a servomechanism that monitors any va...
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air traffic control
air traffic control the system by which airplanes are safely routed into and out of major airports. Air traffic control in the United States is centered in a number of regional control centers that route airplanes along established airways to airport traffic control centers. There Instrument Landin...
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Centers for Disease Control and Prevention
Centers for Disease Control and Prevention (CDC), agency of the U.S. Public Health Service since 1973, with headquarters in Atlanta; it was established in 1946 as the Communicable Disease Center. The CDC is the federal agency responsible for administering national programs for the prevention and co...
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control systems
control systems combinations of components (electrical, mechanical, thermal, or hydraulic) that act together to maintain actual system performance close to a desired set of performance specifications. Open-loop control systems (e.g., automatic toasters and alarm clocks) are those in which the outpu...
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feedback
feedback arrangement for the automatic self-regulation of an electrical, mechanical, or biological system by returning part of its output as input. A simple example of feedback is provided by a governor on an engine; if the speed of the engine exceeds a preset limit, the governor reduces the supply...
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Fort Union
Fort Union trading post of the American Fur Company, erected in 1828 near the confluence of the Yellowstone and Missouri rivers, on the Mont.-N.Dak. line; it controlled converging routes of travel from the Rocky Mts. For c.40 years it was the most important post in the U.S. fur country and was unde...
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operon
operon in genetics , site on a bacterial chromosome containing genes that control protein synthesis (structural genes) together with a gene that determines whether the structural genes are active or not (operator gene). See nucleic acid .
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paregoric
paregoric , alcoholic solution of opium and camphor first prepared in the 18th cent. Because of the constipating effect of opium, paregoric has been used to control diarrhea. It was formerly a constituent of many cough elixirs.
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biofeedback
biofeedback method for learning to increase one's ability to control biological responses, such as blood pressure, muscle tension, and heart rate. Sophisticated instruments are often used to measure physiological responses and make them apparent to the patient, who then tries to alter and ultimatel...
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Marie Carmichael Stopes
Marie Carmichael Stopes , 1880-1958, English paleobotanist and eugenicist, b. Edinburgh, D.Sc. Univ. of London, Ph.D. Univ. of Munich. She lectured on paleobotany at the universities of London and Manchester. In 1921, with Humphrey Verdon Roe, her second husband, she founded the first birth-control ...
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