Columbia Encyclopedia

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nuclear reactor

(Encyclopedia)CE5 Power reactor system nuclear reactor, device for producing controlled release of nuclear energy. Reactors can be used for research or for power production. A research reactor is designed to pr...

air pollution

(Encyclopedia)air pollution, contamination of the air by noxious gases and minute particles of solid and liquid matter (particulates) in concentrations that endanger health. The major sources of air pollution are t...

power, electric

(Encyclopedia)power, electric, energy dissipated in an electrical or electronic circuit or device per unit of time. The electrical energy supplied by a current to an appliance enables it to do work or provide some ...

Moore, Henry

(Encyclopedia)Moore, Henry, 1898–1986, English sculptor. Moore's early sculpture was angular and rough, strongly influenced by pre-Columbian art. About 1928 he evolved a more personal style which has gained him a...

isomorphism

(Encyclopedia)isomorphism īˌsəmôrˈfĭzəm [key], of minerals, similarity of crystal structure between two or more distinct substances. Sodium nitrate and calcium sulfate are isomorphous, as are the sulfates of...

elasticity

(Encyclopedia)elasticity, the ability of a body to resist a distorting influence or stress and to return to its original size and shape when the stress is removed. All solids are elastic for small enough deformatio...

cube

(Encyclopedia)cube, in geometry, regular solid bounded by six equal squares. All adjacent faces of a cube are perpendicular to each other; any one face of a cube may be its base. The dimensions of a cube are the le...

schipperke

(Encyclopedia)schipperke skĭpˈərkē [key], a breed of small nonsporting dog developed in Belgium several hundred years ago. It stands about 13 in. (33 cm) high at the shoulder and weighs from 14 to 18 lb (6.4–...

porphyry, igneous rock

(Encyclopedia)porphyry pôrˈfərē [key], igneous rock composed of large, conspicuous crystals (phenocrysts) and a groundmass in which the phenocrysts are embedded. Some authorities consider the expression “porp...

tympanum

(Encyclopedia)CE5 Tympanum (west pediment, temple of Aphaia at Aegina) tympanum tĭmˈpənəm [key]. In architecture, the triangular space of a pediment, or low-pitched gable, above a portico, door, or window. ...