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absorption spectrum
absorption spectrum A spectrum that consists primarily of dark absorption lines, created when light from a hot source passes through cooler material. The spectra of normal, cool stars such as the Sun fall into this category....
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convection
convection mode of heat transfer in fluids (liquids and gases). Convection depends on the fact that, in general, fluids expand when heated and thus undergo a decrease in density (since a given volume of the fluid contains less matter at a higher temperature than at the original, lower temperature...
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Whitehall
Whitehall 1 City (1990 pop. 20,572), Franklin co., central Ohio, a suburb of Columbus ; inc. 1948. Manufactures include water coolers and packaged meats. A large federal defense construction supply center is there. 2 Borough (1990 pop. 14,451), Allegheny co., SW Pa., a residential suburb of P...
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cinquefoil
cinquefoil [O.Fr.,=five leaves], name for any plant of the widely distributed genus Potentilla of the family Rosaceae ( rose family), chiefly herbs of north temperate and subarctic regions. Most cinquefoils are perennial; many but not all of them have leaves of five leaflets, for which they are ...
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Orazio Gentileschi
Orazio Gentileschi , c.1562-c.1639, Tuscan painter, b. Pisa. His real surname was Lomi, but he adopted his uncle's name. He studied in Rome, where he was associated with Agostino Tassi in the decoration of palace interiors. Influenced by Caravaggio , Gentileschi developed a more softly luminous lig...
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hashish
hashish , resin extracted from the flower clusters and top leaves of the hemp plant, Cannabis sativa, and C. indica. Hashish, called charas in India, is the most potent grade of cannabis and is obtained from cultivated plants grown in hot, moist climates. Marijuana , a cheaper and less potent s...
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limpet
limpet marine gastropod mollusk with a simple, flattened, conical shell, found in cooler waters of the Atlantic and the Pacific oceans. Certain species creep over rocks, feeding on algae during high tides, but when the tide recedes they return instinctively to the same spot occupied previously, t...
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Muhammad Hosni Mubarak
Muhammad Hosni Mubarak , 1928-, president of Egypt (1981-). air force commander (1972-75) and vice president (1975-81), he became president after Anwar al- Sadat was assassinated on Oct. 6, 1981. Mubarak pledged to continue Sadat's policies, particularly the Camp David accords with Israel. He has...
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palmetto palm
palmetto palm or palmetto [Span.,=little palm], common name for palm trees of the genera Sabal and Serenoa, ranging from the sandy pinelands of the S United States to Colombia. Sabal palmetto, the common native palm of the Southeastern states, is one of the trees called cabbage palm; it...
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typhus
typhus any of a group of infectious diseases caused by microorganisms classified between bacteria and viruses, known as rickettsias. Typhus diseases are characterized by high fever and an early onset of rash and headache. They respond to antibiotic treatment with tetracycline and chloramphenicol an...
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