cachalot See sperm whale
cache \'kash\ Temporary computer storage used for quick retrieval of data in order to increase processing speed. The cached data can be stored in a reserved area of RAM, a special cache chip (separate from the CPU) that provides faster access than RAM, or on the disk drive. By keeping frequently accessed data in a rapidly accessible place, the computer can respond quickly to requests for those data without having to perform time-consuming searches of RAM or hard drives. Since a “stale” cache will contain data that have been superseded by later information, the cached data must be refreshed periodically.
cachet, lettre de See lettre de cachet
cactus Any of the flowering plants that make up the family Cactaceae, containing about 1,650 species, native through most of North and South America, with the greatest number and variety in Mexico. Cacti are succulent perennials. Most live in and are well adapted to dry regions. Cacti generally have thick herba¬ ceous or woody stems containing chlorophyll. Leaves usually are absent or greatly reduced, minimiz¬ ing the surface area from which water can be lost; the stem is the site of photosynthesis. The generally thin, fibrous, shallow root systems range widely in area to absorb super¬ ficial moisture. Cacti vary greatly in size and appearance, from buttonlike peyote and low clumps of prickly pear and hedgehog cactus ( Echinocereus) to the upright columns of barrel cacti (Ferocactus and Echinocactus) and the imposing saguaro. Cacti can be distinguished from other succulent
Golden rainbow cactus (Echinocereus dasyacanthus ), a hedgehog cactus, growing in the desert of southwestern Texas.
© ROBERT AND LINDA MITCHELL
© 2006 Encyclopaedia Britannica, Inc.
308 I Cacus and Caca > Caen
plants by the presence of small cushionlike structures (areoles) from which, in almost all species, spines arise, as do flowers, branches, and leaves (when present). Flowers, often large and colourful, are usually solitary. Cacti are widely cultivated as ornamentals. Various species, nota¬ bly prickly pears and chollas, are cultivated as food. Barrel cacti are an emergency source of water for people.
Cacus and Caca \'ka-k9s...'ka-k9\ In Roman religion, brother and sis¬ ter fire deities of the early Roman settlement on the Palatine Hill. Virgil described Cacus as the son of Vulcan and as a fire-breathing brigand who terrorized the countryside. He stole some of the giant Geryon’s cattle from Hercules (see Heracles) and hid them in his lair, but Hercules discovered Cacus’s hiding place and killed him. The story is traditionally connected with the establishment of Hercules’s oldest Roman place of worship, the Ara Maxima, in the Forum Boarium (cattle market).
CAD/CAMVkad-.kam, .kad-'kamX in full computer-aided design/ computer-aided manufacturing. Integration of design and manu¬ facturing into a system under direct control of digital computers. CAD systems use a computer with terminals featuring video monitors and inter¬ active graphics-input devices to design such things as machine parts, pat¬ terns for clothing, or integrated circuits. CAM systems use numerically controlled (see numerical control) machine tools and high-performance programmable industrial robots. Drawings developed during the design process are converted directly into instructions for the production machines, thus optimizing consistency between design and finished prod¬ uct, and providing flexibility in altering machine operations. These two processes are sometimes grouped as CAE (computer-aided engineering).
Cadbury, George (b. Sept. 19, 1839, Birmingham, Warwickshire, Eng.—d. Oct. 24, 1922, Birmingham) British businessman and social reformer. In 1861 he and his brother Richard took over their father’s fail¬ ing business and built it into the highly prosperous Cadbury Brothers cocoa- and chocolate-manufacturing firm. They improved working con¬ ditions and introduced a private social security program for employees. George was also noted for his successful experiments in housing and town planning in Bournville, where he built affordable working-class homes with large gardens.
caddis fly Any member of about 7,000 species of mothlike aquatic insects (order Trichoptera) found worldwide, usually in freshwater habi¬ tats but sometimes in brackish and tidal waters. Generally dull brownish, caddis flies have long antennae and hairy wings that fold rooflike over the abdomen. They feed primarily on plant juices and flower nectar, though a few are predaceous. Many caddis-fly larvae construct a portable case from grains of sand, bits of shells, and plant debris glued together by a sticky substance they secrete. This case surrounds the larva’s abdomen while it matures. Caddis flies are important to freshwater ecosystems because they clean the water by consuming plant and animal debris and serve, as larvae and adults, as an important food for fish, particularly trout.
Caddo One of a group of North American Indian people living mostly in western Oklahoma, U.S. Their language is of the Caddoan language family. Their name derives from a French truncation of kadohadacho, meaning “real chief’ in Caddo. From ancient times they occupied the lower Red River area in Louisiana and Arkansas, and many striking examples of prehistoric pottery and basketry have been found. They were a semisedentary agricultural people who lived in conical pole- and-thatch dwellings. In the 18th century pressures from white settlers pushed many Caddo off their lands, a process that intensified with the Louisiana Purchase in 1803. By 1835 the Caddo had ceded all their land to the U.S., and by 1859 most were living on reservations in Oklahoma. Some 2,700 Caddo claimed sole Caddo descent in the 2000 U.S. census.
Cade's Rebellion (1450) Uprising against the government of Henry VI of England. Jack Cade, an Irishman of uncertain occupation living in Kent, organized a rebellion among local small property holders angered by high taxes and prices. He took the name John Mortimer, identifying
himself with the family of Henry’s rival, the duke of York. Cade and his followers defeated a royal army in Kent and entered London, where they executed the lord treasurer. They were soon driven out of the city; Cade’s followers dispersed on being offered a pardon, and Cade was mortally wounded in Sussex. His rebellion contributed to the breakdown of royal authority that led to the Wars of the Roses.
Cadiz \ko-'diz,\ Spanish Vka-thes\ City (pop., 2001: city, 133,363; metro, area, 400,157), southwestern Spain. Located on a peninsula in the Bay of Cadiz northwest of Gibraltar, it is the main seaport of Cadiz province in Andalusia. Founded as Gadir by Phoenicians from Tyre c. 1100 bc, it was later ruled by Carthage, Rome (as Gades), and the Visigoths. It was held by the Moors beginning in ad 711. In 1262 Cadiz was captured by Alfonso X of Castile-Leon. The city enjoyed great prosperity as a centre for Span¬ ish trade with the American colonies in the 16th—18th centuries (see Sevilla). It now has naval and mercantile shipbuilding yards.
Cadiz, Bay of Inlet of the Gulf of Cadiz, southwestern Spain. An inlet indenting the coast of Cadiz province, it receives the Guadalete River and is partially protected by the Isle of Leon, on which the port of Cadiz is located. The Spanish-U.S. air and naval base at Rota is situated on the bay.
cadmium Metallic chemical element, chemical symbol Cd, atomic num¬ ber 48. It normally occurs along with other metals, especially zinc, in ores. A silvery white metal capable of taking a high polish, cadmium does not corrode under alkaline (see alkali) conditions; one of its major uses is in electroplating other metals and alloys to protect them. Because it absorbs neutrons effectively, it is used in control rods in some nuclear reactors. Its compounds, in which it has valence 2, are very toxic. They are used as pigments, as phosphors in television and computer monitor screens, as pesticides, and in photographic applications and analytical chemistry.