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radioactive isotope

(Encyclopedia)radioactive isotope or radioisotope, natural or artificially created isotope of a chemical element having an unstable nucleus that decays, emitting alpha, beta, or gamma rays until stability is reache...

Pará, state, Brazil

(Encyclopedia)Pará pəräˈ [key], state (1996 pop. 5,552,783), 474,896 sq mi (1,229,981 sq km), N Brazil, in the lower Amazon River basin bordering on the Guianas and the Atlantic Ocean. Belém is the capital. Mo...

style, in literature

(Encyclopedia)style, in literature, the mysterious yet recognizable result of a successful blending of form with content. Generally speaking, all the arts reflect one of two stylistic tendencies: the classical or t...

swamp

(Encyclopedia)swamp, shallow body of water in a low-lying, poorly drained depression, usually containing abundant plant growth dominated by trees, such as cypress, and high shrubs. Swamps develop in moist climates,...

oxidation and reduction

(Encyclopedia)oxidation and reduction, complementary chemical reactions characterized by the loss or gain, respectively, of one or more electrons by an atom or molecule. Originally the term oxidation was used to re...

fracture

(Encyclopedia)fracture, breaking of a bone. A simple fracture is one in which there is no contact of the broken bone with the outer air, i.e., the overlying tissues are intact. In a comminuted fracture the bone is ...

Waco

(Encyclopedia)Waco wāˈkō [key], city (1990 pop. 103,590), seat of McLennan co., E central Tex., on the Brazos River, just below the mouth of the Bosque; inc. 1856. It is a rail junction and a trading, shipping, ...

matter

(Encyclopedia)matter, anything that has mass and occupies space. Matter is sometimes called koinomatter (Gr. koinos=common) to distinguish it from antimatter, or matter composed of antiparticles. The atomic th...

flood, in hydrology

(Encyclopedia)flood, inundation of land by the rise and overflow of a body of water. Floods occur most commonly when water from heavy rainfall, from melting ice and snow, or from a combination of these exceeds the ...

Arte Povera

(Encyclopedia)Arte Povera [Ital.,=poor art], influential art movement that arose in Italy in the late 1960s. It was championed by the Italian art critic Germano Celant, who also named (1967) the movement. It was ch...