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tropics

(Encyclopedia)tropics, also called tropical zone or torrid zone, all the land and water of the earth situated between the Tropic of Cancer at lat. 231⁄2°N and the Tropic of Capricorn at lat. 231⁄2°S. Every po...

Umayyad

(Encyclopedia)Umayyad o͞omäˈyäd [key], the first Islamic dynasty (661–750). Their reign witnessed the return to leadership roles of the pre-Islamic Arab elite, and the rejuvenation of tribal loyalties. The Ba...

polymer

(Encyclopedia)CE5 A. Addition polymerization: Two ethylene molecules, C2H4, combine to form two links in the polyethylene chain molecule (C2H4)n. B. Condensation polymerization: Two glycine molecules, NH2CH2COOH...

radio-frequency identification

(Encyclopedia)radio-frequency identification (RFID), a technology that uses radio waves to transmit data and uniquely identify an animal, person, or thing. An RFID system typically consists of a tag and a reader. T...

particle detector

(Encyclopedia)CE5 Particle detector—Bubble chamber: A. Pressure drops as piston is raised; B. Charged particles passing through chamber ionize atoms in liquid; C. Bubbles form around atoms and form visible tra...

Franco, Francisco

(Encyclopedia)Franco, Francisco fränthēsˈkō frängˈkō [key], 1892–1975, Spanish general and caudillo [leader]. He became a general at the age of 32 after commanding the Spanish Foreign Legion in Morocco. Du...

Fujimori, Alberto

(Encyclopedia)Fujimori, Alberto älbĕrˈtō fo͞oˌjĭmôrˈē [key], 1938–, president of Peru (1990–2000), b. Lima, Peru. The son of Japanese immigrants, he was educated in Peru and attended Univ. of Wisconsi...

electron tube

(Encyclopedia)CE5 Triode electron tube electron tube, device consisting of a sealed enclosure in which electrons flow between electrodes separated either by a vacuum (in a vacuum tube) or by an ionized gas at l...

gun control

(Encyclopedia)gun control, government limitation of the purchase and ownership of firearms. The availability of guns is controlled by nations and localities throughout the world. In the United States the “right o...

Katharine of Aragón

(Encyclopedia)Katharine of Aragón, 1485–1536, first queen consort of Henry VIII of England; daughter of Ferdinand II of Aragón and Isabella of Castile. In 1501 she was married to Arthur, eldest son of Henry VII...