number and kind of legal issues surrounding the technology. Hotly debated issues include the obscenity of some on-line sites, the right of pri¬ vacy, freedom of speech, regulation of electronic commerce, and the appli¬ cability of COPYRIGHT laws.
cybernetics Science of regulation and control in animals (including humans), organizations, and machines when they are viewed as self- governing whole entities consisting of parts and their organization. It was conceived by Norbert Wiener, who coined the term in 1948. Cybernetics views communication and control in all self-contained complex systems as analogous. It differs from the empirical sciences (physics, biology, etc.) in not being interested in material form but in organization, pattern, and communication in entities. Because of the increasing sophistication of computers and the efforts to make them behave in humanlike ways, cyber¬ netics today is closely allied with artificial intelligence and robotics, and it draws heavily on ideas developed in information theory.
eye ad \'s!-kod\ Any of the palmlike woody plants that constitute the order Cycadales, containing four families: Cycadaceae, Zamiaceae, Stan- geriaceae, and Boweniaceae. Cycads have crowns of large, feathery com¬ pound leaves and cones at the ends of their branches. Some have tall, unbranched, armourlike trunks; others have partially buried stems with swollen trunks. Slow-growing cycads are used as ornamental conserva¬ tory plants, but some survive outdoors in temperate regions. The stems of some cycads yield starch that is edible if thoroughly cooked. The young leaves and seeds of others also are edible.
Cyclades VsI-klo-.dezX Greek Kikladhes \ke-'kla-thes\ Group of about 30 islands, southern Aegean Sea. They cover a land area of 976 sq mi (2,528 sq km) and constitute the Cyclades department of Greece, which has its capital at Ermoupolis. Their name refers to the ancient tradition that they formed a circle around the sacred island of Delos. The chief islands are Andros, Tfnos, Naxos, Amorgos, Melos, Paros, Syros, Kea, Kfthnos, Serifos, Ios, and Thira. They were the centre of a Bronze Age culture—the Cycladic, noted for its white marble idols—and later belonged to the Mycenaean culture in the 2nd millennium bc. Colonized by Ionians in the 10th-9th century bc, they later were successively held by Persians, Athenians, Ptolemaic Egyptians, and Macedonians. Ruled by Venice after the eai'ly 13th century ad, the islands fell to the Turks at dif¬ ferent times during the 16th to 18th centuries. They became part of Greece in 1829. The economy is now based on tourism and on the export of wine, hides, pottery, and handicrafts.
cyclamen VsI-klo-monX Any of about 15 species of flowering perennial herbaceous plants that make up the genus Cyclamen, in the primrose fam¬ ily (Primulaceae), native to the Middle East and southern and central Europe. The florist’s cyclamen (C. persicum), the best-known species, is an indoor plant cultivated for its attractive white to pink to deep red flow¬ ers. Long-stalked, rounded, or kidney-shaped leaves, often variously marked, grow from the base of the plant, which has no aboveground stem. Solitary flowers grow on stalks less than 12 in. (30 cm) tall.
cycling Use of the bicycle in competitive sport or in recreation. The clas¬ sic professional races are held mainly in Europe; the first was held in Paris in 1868. There are basically two types of race: road races and track races. The first U.S. cycling competition, a six-day race, was held in 1891. Six- day racing was reintroduced to Europe as a two-man team event in the 20th century, but it has largely died out in the U.S. The first Tour de France, the premier race, was held in 1903. Cycling has been part of the Olym¬ pics since the first modern games in 1896. Events include a variety of open-road and circuit races for both men and women.
cyclone Any large system of winds that circulates about a centre of low atmospheric pressure in a counterclockwise direction north of the Equa¬ tor and in a clockwise direction south of it. Cyclones that occur in the mid- and high latitudes are known as extratropical cyclones; they are fre¬ quently preceded by thickening and lowering clouds, followed by pre¬ cipitation. Cyclones that form in the lower latitudes are known as tropical cyclones; smaller than extratropical cyclones, they tend to be more vio¬ lent and can cause considerable damage (see tropical cyclone). Wind sys¬ tems that circulate around a high-pressure centre in directions opposite to that of cyclones are known as anticyclones.
Cyclops \'sl-,klaps\ In Greek mythology, any of several one-eyed giants. In the Odyssey, the Cyclopes were cannibals who lived in a faraway land (traditionally Sicily). Odysseus was captured by the Cyclops Polyphemus, but he escaped being devoured by blinding the giant. According to Hesiod,
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500 i cyclotron ► Cyprus
there were three Cyclopes (Arges, Brontes, and Steropes) who forged thunderbolts for Zeus. In a later tradition, they were assistants to Hephaes¬ tus in this task. Apollo destroyed them after one of their thunderbolts killed Asclepius.
cyclotron VsI-klo-.traM Particle accelerator that accelerates charged atomic or subatomic particles in a constant magnetic field. It consists of two hollow semicircular electrodes, called dees, in a large evacuated cylindri¬ cal box. An alternating electric field between the dees continuously accel¬ erates the particles from one dee to the other, while the magnetic field guides them in a circular path. As the speed of the particles increases, so does the radius of their path, and the particles spiral outward. In this man¬ ner, a cyclotron can accelerate protons to energies of up to 25 million electron volts.
Cydones VsI-'do-nezV, Demetrius (b. c. 1324, Thessalonica, Byzan¬ tine Empire—d. c. 1398, Crete) Byzantine humanist scholar, statesman, and theologian. After studying under a Greek scholar, he made Greek translations of St. Augustine and St. Thomas Aquinas. He was twice prime minister of the Byzantine empire (1369-83, 1391-96). An academy of Greek culture that he established in Venice in 1390 diffused Greek thought throughout Italy, stimulating the Italian Renaissance. A convert to Latin Catholicism, he worked unsuccessfully for East-West Christian unity; in his Symbouleutikoi (“Exhortations”) he vainly encouraged the Byzantine people to unite with the Latins against the Turks. He is considered the most brilliant Byzantine writer of the 14th century.
Cygnus Vsig-nosV A Radio-emitting galaxy lying in the constellation Cygnus, about 700 million light-years from Earth. It is the brightest cos¬ mic source of radio waves in the sky and the first radio galaxy to be detected. Because of its peculiar divided appearance, it was once thought to be two galaxies colliding. Astronomers now believe it to be a single galaxy with a large black hole at its core; emanating from this central region are two opposing jets of hot gas that end in radio- and X-ray- emitting lobes called "hot spots." See also active galactic nucleus.
cylinder See piston and cylinder
cylinder seal Small stone cylinder engraved in intaglio on its surface to leave impressions when rolled on wet clay. It first appeared c. 3400- 2900 bc and is considered to be one of the finest artistic achievements of Mesopotamia. The earliest examples used geometric or animal patterns; later seals incorporated the owner’s name and depicted a variety of motifs. They were used to mark personal property and make documents legally binding. The seals were adopted in Egypt and the Indus civilization.
cymbal Percussion instrument consisting of a circular metal plate that is struck with a drumstick or two such plates that are struck together. They were used, often ritually, in Assyria,
Israel (from c. 1100 bc), Egypt, and other ancient civilizations, spread to East Asia, and reached Europe by the 13th century ad. Western orchestral cymbals derive from those used in the Turkish military bands in vogue in 18th-century Europe. Though Asian cymbals are often flat. Middle Eastern and Western cymbals usually have a central concave dome, or boss, so that only the edges touch when they are clashed. The finest cymbals have long been manufac¬ tured in Turkey by means of closely guarded techniques. In popular music, cymbals are not clashed manually; instead, a cymbal sus¬ pended on a sticklike stand may be brushed or struck, and horizontal “hi-hat” cymbals are clashed lightly by use of a pedal mechanism.