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Dietrich ► diffusion I 545

nutrition and are most effective combined with exercise. Appetite sup¬ pressants may have dangerous side effects. Excessive weight loss may be a sign of anorexia nervosa.

Dietrich Vde-trik,\ English Vde-trikA, Marlene orig. Maria Magdalene Dietrich (b. Dec.

27, 1901, Berlin, Ger.—d. May 6,

1992, Paris, France) German-U.S. film actress and singer. After joining Max Reinhardt’s theatre company in 1922, she appeared in German films and became an international star as the destructive cabaret singer Lola- Lola in Josef von Sternberg’s The Blue Angel (1930). Sternberg took her to Hollywood, where they made many films together, including Morocco (1930), Shanghai Express (1932), and The Scarlet Empress (1934), which established her aura of glamorous sophistication and lan¬ guid sensuality. During World War II she made over 500 appearances before Allied troops. She also starred in films such as Destry Rides Again (1939), A Foreign Affair (1948), Witness for the Prosecution (1957), and Touch of Evil (1958). She toured widely as a nightclub performer into the 1960s, singing trademark songs such as “Falling in Love Again.”

Dietz \'dets\ A Howard (b. Sept. 9, 1896, New York, N.Y., U.S.—d. July 30, 1983, New York City) U.S. songwriter. He studied at Columbia University and later joined an advertising agency, where he designed the trademark roaring lion for Goldwyn Pictures (later MGM). He joined the film studio in 1919 and became director of advertising, a post he held until 1957. From 1923 he wrote lyrics in his spare time. In 1929 he met the composer Arthur Schwartz (1900-84); the duo established their repu¬ tation with The Little Show and went on to write such Broadway shows as Three’s a Crowd (1930), The Band Wagon (1931), and The Gay Life (1961). Dietz wrote about 500 songs; the Dietz-Schwartz collaborations include “Something to Remember You By,” “Dancing in the Dark,” and “You and the Night and the Music.”

Dievs \'de-9fs\ In the pre-Christian Baltic religion, the sky god. Along with the goddess Laima, he determined the course of the world and human destiny. He was pictured as a Baltic king who lived on a farmstead in the heavens, occasionally descending to earth on horseback or in a chariot to serve as the protector of farmers and their crops. His two sons were the morning and evening stars. In modern Baltic, dievs refers to the Chris¬ tian God.

Diez \'dets\, Friedrich Christian (b. March 15, 1794, Giessen, Hesse- Darmstadt—d. May 29, 1876, Bonn, Ger.) German linguist, regarded as the founder of Romance philology. He began his career as a scholar of medieval Provencal poetry and taught literature at the University of Bonn from 1823 to the end of his life. Diez applied the methodology of com¬ parative linguistics pioneered by Jacob Grimm and Franz Bopp to the Romance languages. In his Grammar of the Romance Languages (1836— 44) and Etymological Dictionary of the Romance Languages (1853), he demonstrated the relationship of “Vulgar” or Spoken Latin to Classical Latin and the evolution of Romance languages from Spoken Latin into their modern forms.

difference equation Equation involving differences between succes¬ sive values of a function of a discrete variable (i.e., one defined for a sequence of values that differ by the same amount, usually 1). A function of such a variable is a rule for assigning values in sequence to it. For example,/(x + 1) = x/(x) is a difference equation. Methods developed for solving such equations have much in common with methods for solving linear differential equations, which difference equations are often used to approximate.

differential In calculus, an expression based on the derivative of a func¬ tion, useful for approximating certain values of the function. The differ¬ ential of an independent variable x, written Ax, is an infinitesimal change in its value. The corresponding differential of its dependent variable y is given by Ay = /(x + Ax) - /(x). Because the derivative of the function /(x), f'(x), is equal to the ratio as Ax approaches zero (see limit), for

small values of Ax, Ay =/'(x)Ax. This formula often enables a quick and fairly accurate approximation to be made for what otherwise would be a tedious calculation.

differential calculus Branch of mathematical analysis, devised by Isaac Newton and G.W. Leibniz, and concerned with the problem of find¬ ing the rate of change of a function with respect to the variable on which it depends. Thus it involves calculating derivatives and using them to solve problems involving nonconstant rates of change. Typical applications include finding maximum and minimum values of functions in order to solve practical problems in optimization.

differential equation Mathematical statement that contains one or more derivatives. It states a relationship involving the rates of change of continuously changing quantities modeled by functions. Differential equa¬ tions are very common in physics, engineering, and all fields involving quantitative study of change. They are used whenever a rate of change is known but the process giving rise to it is not. The solution of a differen¬ tial equation is generally a function whose derivatives satisfy the equa¬ tion. Differential equations are classified into several broad categories. The most important are ordinary differential equations (ODEs), in which change depends on a single variable, and partial differential equations (PDEs), in which change depends on several valuables. See also differen¬ tiation.

differential gear In automotive mechanics, a gear arrangement that transmits power from the engine to a pair of driving wheels, dividing the force equally between them but permitting them to follow paths of dif¬ ferent lengths, as when turning a comer or traversing an uneven road. On a straight road the wheels rotate at the same speed; when turning a cor¬ ner the outside wheel has farther to go and would turn faster than the inner wheel if unrestrained. The automobile differential was invented in 1827; originally used on steam-driven vehicles, it was well known when internal-combustion engines finally appeared.

differential geometry Field of mathematics in which methods of cal¬ culus are applied to the local geometry of curves and surfaces (i.e., to a small portion of a surface or curve around a point). A simple example is finding the tangent line on a two-dimensional curve at a given point. Similar operations may be extended to calculate the curvature and length of a curve and to analogous properties of surfaces in any number of dimensions.

differential operator In mathematics, any combination of derivatives applied to a function. It takes the form of a polynomial of derivatives, such as D 2 XX - D 2 xy • D 2 yx , where D 2 is a second derivative and the subscripts indicate partial derivatives. Special differential operators include the gra¬ dient, divergence, curl, and Laplace operator (see Laplace's equation). Dif¬ ferential operators provide a generalized way to look at differentiation as a whole, as well as a framework for discussion of the theory of differen¬ tial EQUATIONS.

differentiation Mathematical process of finding the derivative of a function. Defined abstractly as a process involving limits, in practice it may be done using algebraic manipulations that rely on three basic formulas and four rules of operation. The formulas are: (1) the derivative of x" is nxP ~ 1 , (2) the derivative of sin x is cos x, and (3) the derivative of the exponential function e x is itself. The rules are: (1) ( af+ bg)' = af + bg\ (2) (fg)' =fg' + gf, (3) (fig)' = (gf -fg')/g 2 , and (4) (f(g))'=f\g)g\ where a and b are constants,/and g are functions, and a prime (') indi¬ cates the derivative. The last formula is called the chain rule. The deri¬ vation and exploration of these formulas and rules is the subject of DIFFERENTIAL CALCULUS. See also INTEGRATION.

diffraction Spreading of waves around obstacles. It occurs with water waves, sound, electromagnetic waves (see electromagnetic radiation), and small moving particles such as atoms, neutrons, and electrons, which show wavelike properties. When a beam of light falls on the edge of an object, it is bent slightly by the contact and causes a blur at the edge of the shadow of the object. Waves of long wavelength are diffracted more than those of short wavelength.

diffusion Process by which there is a net flow of matter from a region of high concentration to one of low concentration. It occurs fastest in liq¬ uids and slowest in solids. Diffusion can be observed by adding a few drops of food colouring to a glass of water. The scent from an open bottle of perfume quickly permeates a room because of random motion of the vapour molecules. A spoonful of salt placed in a bowl of water will even¬ tually spread throughout the water.

Marlene Dietrich.

PICTORIAL PARADE

546 I digestion ► dik-dik

digestion Process of dissolving and chemically converting food for absorption by cells. In the mouth, food is chewed, mixed with saliva, which begins to break down starches, and kneaded by the tongue into a ball for swallowing. Peristalsis propels it through the esophagus and the rest of the alimentary canal. In the stomach, food mixes with acid and enzymes, which further break it down. The mixture, called chyme, enters the duodenum, the first part of the small intestine. Bile from the liver breaks up fat globules. Enzymes from the pancreas and intestinal glands act on specific molecules, breaking carbohydrates down into simple sugars, pro¬ teins into amino acids, and fats into glycerol and fatty acids. These prod¬ ucts are absorbed by the bloodstream. Indigestible substances, such as fibre, pass into the large intestine, where water and ions are reabsorbed and feces held for excretion. See illustration opposite.

digestive tract See alimentary canal

digital camera Camera that captures images electronically rather than on film. The image is captured by an array of charge-coupled devices (CCDs), stored in the camera’s random access memory or a special dis¬ kette, and transferred to a computer for modification, long-term storage, or printing out. Since the technology produces a graphics file, the image can be readily edited using suitable software. Models designed and priced for the mass consumer market—as opposed to costly models designed for photojournalism and industrial photography—first became available in 1996. They appeal particularly to users who want to send pictures over the Internet or to crop, combine, enhance, or otherwise modify their pho¬ tographs.

digital certificate Electronic credit card intended for on-line business transactions and authentications on the Internet. Digital certificates are issued by certification authorities (e.g., VeriSign). They typically contain identification information about the holder, including the person’s public key (used for encrypting and decrypting messages), along with the authority’s digital signature, so that the recipient can verify with the authority that the certificate is authentic. Web sites may also have digital certificates, to enable a person intending to buy its products to confirm that it is an authenticated e-commerce site.

digital computer Computer capable of solving problems by process¬ ing information expressed in discrete form. By manipulating combina¬ tions of binary digits (see binary code), it can perform mathematical calculations, organize and analyze data, control industrial and other pro¬ cesses, and simulate dynamic systems such as global weather patterns. See also analog computer.

Digital Subscriber Line See DSL

digital-to-analog conversion (DAC) Process by which digital sig¬ nals (which have a binary state) are converted to analog signals (which theoretically have an infinite number of states). For example, a modem converts computer digital data to analog audio-frequency signals that can be transmitted over telephone lines.

digital video disk See DVD

digitalis \,di-j3-'ta-l3s\ Drug derived from leaves of the common fox¬ glove and used as a drug that strengthens heart muscle contraction. It was first prescribed in the 18th century. Its active principles belong to a class of steroids called cardiac glycosides. Their dosage must be carefully moni¬ tored because the lethal dose may be only three times the effective dose. Digitoxin and digoxin are among the most commonly prescribed forms of digitalis.

diglossia \dI-'glos-e-3\ Coexistence of two varieties of the same lan¬ guage in a speech community, with each variety being more or less stan¬ dardized and occupying a distinct sociolinguistic niche. Typically, one variety is more formal or prestigious while the other is more suited to informal conversation or is taken as a mark of lower social status or less education. Classic diglossic situations can be found in ARABic-speaking communities, where Modern Standard Arabic coexists with dozens of regional Arabic dialects, and among speakers of Dravidian languages such as Tamil, where different words for basic concepts such as “house” or “water” are chosen depending on the speaker’s caste or religion.

Dijon \de-'zho n \ City (pop., 2004 est.: 149,000), east-central France. The site has been occupied from pre-Roman times. It became the capital of the duchy of Burgundy in 1015 and prospered under the Valois dynasty (1364-1477). Louis XI annexed the city in the late 15th century. Its his¬ toric buildings include a 13th-century church and 14th-century town hall

palate — tongue —

teeth-

epiglottis

salivary glands -pharynx

esophagus

stomach pancreas

colon cecum- sigmoid colon rectum -

small

intestine

___l_

duodenum jejunum — ileum

appendix

anus

Major organs of the human digestive system. Food taken in by the mouth is guided by the tongue as it is sheared and ground by the teeth. The bolus of chewed food is moistened and lubricated with saliva secreted by the salivary glands. Enzymes in the saliva begin the breakdown of starches. The epiglottis, a flap of tissue, prevents food from the pharynx from entering the larynx during swallowing. Muscles in the esophagus wall contract in waves to move the food to the stomach. Gastric juices secreted by the stomach contain a mixture of substances (including enzymes and hydrochloric acid) that break down the food into a semiliquid mass called chyme. The chyme passes into the small intestine, where food molecules are broken down into sugars, amino acids, and fatty acids. These useful substances are absorbed into the bloodstream as the food passes through the duodenum, jejunum, and ileum. The pancreas secretes digestive enzymes into the duodenum. The liver secretes bile salts that make insoluble fats entering the small intestine water-soluble and vulnerable to enzymatic action. Excess bile salts are stored in the gallbladder. The large intestine (colon) serves to remove water and electrolytes from the digested chyme and to compact and store undigestible material, called feces. Fecal matter is moved by muscular contractions into the rectum and expelled from the anus.

(the former palace of the dukes of Burgundy). Its university was founded in 1722. A market and tourist centre, it is still known for its food prod¬ ucts (e.g., mustard, vinegar, and gingerbread).

dik-dik Any of four species of delicate African antelope (genus Madoqua ), named for the sound it makes when alarmed. It stands 12-16 in. (30-40 cm) high at the shoulder and weighs 7-11 lbs (3-5 kg). It has an elongated snout and a soft coat that is gray or brownish above, white below. The hair on the crown forms an upright tuft and may partially con¬ ceal the short, ringed horns of the male. Dik-diks live in dry areas of dense brush in southern and eastern Africa, and feed chiefly on acacia and other shrubs. See photograph on opposite page.

dike ► diminishing returns I 547

dike Bank, usually of earth, constructed to control or confine water. Dikes were purely defensive at first but later became a means to acquire polders (tracts of land reclaimed from a body of water through the con¬ struction of offshore dikes roughly parallel to the shoreline). After a dike is built, the polder is drained by pumping out the water. Where the land surface is above low-tide level, tide gates discharge water into the sea at low tide and automatically close to prevent reentry of seawater at high tide. To reclaim lands that are below low-tide level, the water must be pumped over the dikes. The most notable example of polder construction is the system adjacent to Holland’s IJsselmeer (Zuider Zee) barrier dam. If The Netherlands were to lose the protection of its dikes, its most densely populated portion would be inundated by the sea and rivers.

dilemma tale or judgment tale Typical African form of short story. Its ending is open to conjecture or is morally ambiguous, allowing the audience to comment or speculate on the correct solution to the problem posed, whether a conflict of loyalty, the need to choose a just response to a difficult situation, or the laying of blame when several parties seem equally guilty. Dilemma tales function both as instruction and entertain¬ ment and help establish social norms.

Dili City (pop., 1999 est: 65,000), capital of East Timor. It lies on the northern coast of Timor Island on Ombai Strait. Dili has been the capital, chief port, and commercial centre of the eastern half of Timor since it was settled by the Portuguese about 1520. During World War II it was occu¬ pied by Japan. East Timor was under Portuguese rule until 1975, after which it was designated a province of Indonesia. Dili suffered major damage by Indonesian military “militias” after East Timor voted for inde¬ pendence in 1999. The city became the capital of newly sovereign East Timor in 2002.

Dilke \'dilk. Sir Charles Wentworth, 2nd Baronet (b. Sept. 4, 1843, London, Eng.—d. Jan. 26, 1911, London) British politician. He was elected to Parliament in 1868, first as an extremist then as a moderate. In 1882 he became a member of William E. Gladstone’s cabinet and was seen as a future prime minister. He was ruined at the height of his career when he was cited as a corespondent in a sensational divorce suit in 1886. Dilke denied the woman’s story, and the accumulated evidence showed that much of it was a fabrication. He returned to the House of Commons (1892-1911), where he promoted progressive labor legislation and gained a reputation as a military expert.

dill FENNEL-like annual or biennial herb (Anethum graveolens) of the pars¬ ley family or its dried ripe fruit (seeds) and leafy tops, which are used to season foods. Native to Mediterranean countries and southeastern Europe, dill is now widely cultivated in Europe, India, and North America. The entire plant is aromatic. Particularly in eastern Europe and Scandinavia, the small stems and immature umbels are used for flavouring foods. Dill has a warm, slightly sharp flavour.

Dillinger Vdil-on-jorV, John (Herbert) (b. June 28, 1902, or June 22, 1903, Indianapolis, Ind., U.S.—d. July 22, 1934, Chicago, Ill.) U.S. bank robber. Arrested in 1924 in the foiled holdup of a grocer in Mooresville, Ind., he spent the next several years in Indiana state prisons, where he learned the craft of bank robbery from tough professionals. After his parole in 1933, he and one to four confederates committed five bank rob¬ beries in Indiana and Ohio in a period of four months. Again captured and

imprisoned, he escaped with the help of other convicts whose own escape he had earlier financed and plotted. He and his gang then robbed banks in Indiana and Wisconsin and fled south to Florida and then to Tucson, Ariz., where they were discovered and arrested by local police. In 1934 he used a fake wooden pistol to effect yet another escape from an Indiana prison. His end came in an ambush set by the Federal Bureau of Investigation, Indiana police, and Dillinger’s friend Anna Sage, a brothel madam. The well-publicized “lady in red” drew Dillinger to the Biograph Theatre in Chicago, where, on emerging, he was shot to death.

Dilthey Vdil-.tlX, Wilhelm (b. Nov. 19, 1833, Biebrich, Nassau, Ger.—d. Oct. 1, 1911, Seis am Schlern, South Tirol, Austria-Hungary) German philosopher of history. Opposed to contemporary efforts to trans¬ form the methodology of the humanities and the social sciences on the model of natural science, Dilthey tried to establish these fields as inter¬ pretive sciences in their own right. Their subject matter, according to him, is the human mind, not as it is enjoyed in immediate experience nor as it is analyzed in psychological theory, but as it manifests or “objectifies” itself in languages and literatures, actions, and institutions. Dilthey emphasized that the essence of human beings cannot be grasped by intro¬ spection but only from a knowledge of all of history; this understanding, however, can never be final because history itself never is. His major work is Introduction to Human Science (1883); two influential essays are “Ideas Concerning a Descriptive and Analytical Psychology” (1894) and “The Structure of the Historical World in the Human Sciences” (1910).

DiMaggio \d3-'ma-zhe-,o, di-'ma-je-.oX, Joe orig. Joseph Paul DiMaggio (b. Nov. 25, 1914, Martinez, Calif., U.S.—d. March 8, 1999, Hollywood, Fla.) U.S. baseball star. DiMaggio joined the New York Yan¬ kees in 1936 and stayed with them until his retirement in 1951. Regarded as one of the greatest of all centre fielders, he played outfield with such languid grace that some inattentive fans thought he was lazy. Known as “Joltin’ Joe” or “the Yankee Clipper,” he achieved a career batting aver¬ age of .325. In 1941 he accomplished one of the most remarkable of all major league records with his feat of hitting safely in 56 consecutive games. DiMaggio helped the Yankees win 10 American League champi¬ onships and 9 World Series titles. His brothers Vincent and Dominic also played in the major leagues. DiMaggio’s second wife (for nine months in 1954) was Marilyn Monroe. After his retirement from baseball he served as an executive for two major-league teams and appeared in tele¬ vision commercials.

dimension In mathematics, a number indicating the fewest coordinates necessary to identify a point in a geometric space; more generally, a num¬ ber indicating a measurement of length (see length, area, and volume). One-dimensional space can be represented by a numbered line, on which a single number identifies a point. In two-dimensional space, a coordinate system may be superimposed, requiring only two numbers to identify a point. Three numbers suffice in three-dimensional space, and so on.

dimensional analysis Technique used in the physical sciences and engineering to reduce physical properties such as acceleration, viscosity, energy, and others to their fundamental dimensions of length, mass, and time. This technique facilitates the study of interrelationships of systems (or models of systems) and their properties. Acceleration, for example, is expressed as length per unit of time squared; whether the units of length are in the English or metric system is immaterial. Dimensional analysis is often the basis of mathematical models of real situations.

dimethyl ketone See acetone

dimethyl sulfoxide (DMSO) Xdl-'me-thol-sol-'fak-.sIdV Colourless, nearly odourless liquid organic compound. It mixes in all proportions with water, ethanol, and most organic solvents and dissolves a wide variety of compounds (but not aliphatic hydrocarbons). It readily penetrates skin and other tissues and is used to carry drugs and antitoxins through the skin. It has many nonmedical uses—as a solvent, cleaner, pesticide, paint strip¬ per, hydraulic fluid, preservative of cells at low temperatures, and metal complexing agent.

diminished responsibility or diminished capacity In law, doc¬ trine that absolves an accused person of part of the liability for his crimi¬ nal act if he suffers from such abnormality of mind as to substantially impair his responsibility in committing or being a party to an alleged vio¬ lation. The doctrine provides a mitigating defense in cases in which the mental disease or defect is not of such magnitude as to exclude criminal responsibility altogether. Diminished responsibility is most frequently asserted as a defense to murder charges that require proof of a particular mental state (e.g., premeditation). If diminished responsibility is shown, negating an element of the crime with which a defendant is charged, the defendant can be convicted only of a lesser offense that does not include the element. Although diminished responsibility is recognized as a defense in Britain, most other countries recognize only mental disease or abnormality of sufficient degree to sustain a defense of insanity.

diminishing returns, law of Economic law stating that if one input used in the manufacture of a product is increased while all other inputs

Dik-dik (Madoqua)

JACK CANNON-OSTMAN AGENCY

548 I Dimitrov ► Dinwiddie

remain fixed, a point will eventually be reached at which the input yields progressively smaller increases in output. For example, a farmer will find that a certain number of farm labourers will yield the maximum output per worker. If that number is exceeded, the output per worker will fall.

Dimitrov Vdi-'me-.trofV Georgi (Mikhailovich) (b. June 18, 1882, Kovachevtsi, Bulg.—d. July 2, 1949, near Moscow, Russia, U.S.S.R.) Bulgarian communist leader. He helped found the Bulgarian Communist Party in 1919. After leading a communist uprising in 1923 that provoked fierce government reprisals, he was forced to live abroad and became head of the central European section of the Comintern in Berlin (1929-33). He won worldwide fame for his defense against Nazi accusations in the Reichs¬ tag fire trial of 1933. He headed the Comintern in Moscow (1935—43), then returned to Bulgaria, where he served as prime minister (1945-49). He effected the communist consolidation of power that formed the Bul¬ garian People’s Republic in 1946.

Dinarchus or Deinarchus \dl-'nar-k9s\ (b. c. 360 bc —d. after 292) Professional speechwriter at Athens. He rose to fame through his speeches against Demosthenes and others accused of misusing the treasury. His work, however, reflects the decline of Attic oratory; his surviving speeches show little creativity, abuse instead of reason, and plagiarism.

cTlndy, Vincent See Vincent d’lNDY

Dinesen Vde-no-sonV Isak orig. Karen Christence Dinesen later Baroness Blixen-Finecke (b. April 17, 1885, Rungsted, Den.—d. Sept. 7, 1962, Rungsted) Danish writer. Dinesen married her cousin, a baron, and they moved to Kenya; Out of Africa (1937; film, 1985), a memoir of her years on their coffee plantation (1914-31), reveals a deep love of Africa and its people. Her characteristic writings took the form of highly polished narratives in the Romantic tradition, set in the past and pervaded with an aura of supematuralism; they incorporate themes of eros and dreams. Her collections include Seven Gothic Tales (1934) and Win¬ ter’s Tales (1942).

Ding Ling Vdig-'ligX or Ting Ling orig. Jiang Wei (b. 1904, Changde, Hunan province, China—d. March 4, 1986, Beijing) Chinese writer. She had written three collections, many of which contained stories centred on young, unconventional Chinese women, before publishing the proletarian-oriented Flood (1931), acclaimed as a model of Socialist Real¬ ism. She later expressed dissatisfaction with the government officials, for which she was censured and imprisoned during the Cultural Revolution; she was eventually reinstated in the party. Her later works include critical essays and fiction, some published in I Myself Am a Woman (1989).

dingo Australian wild dog ( Canis dingo, C. familiaris dingo, or C. lupus dingo), apparently introduced from Asia 3,500^1,000 years ago. It has short, soft fur, a bushy tail, and erect, pointed ears. It is about 4 ft (1.2 m) long, including the 12-in. (30-cm) tail, and stands about 24 in. (60 cm) tall at the shoulder. Its colour varies from yellowish to reddish brown, often with white underparts, paws, and tail tip. Dingoes hunt alone or in small groups. They formerly preyed mostly on kangaroos but now feed mainly on rabbits and sometimes on livestock. They contributed, through competition for resources, to the extermination of the Tasmanian wolf and the Tasmanian devil on the Australian mainland.

Dinka Cattle-herding people of the Nile basin in southern Sudan. They speak an eastern Sudanic language of the Nilo-Saharan family and are closely related to the Nuer. Numbering about four million, they are divided into independent groups of 1,000-30,000 persons. Leadership is provided by priest-chiefs. In recent years they have been involved in civil war. See also Nilot.

dinoflagellate V.dl-no-'fla-jo-lotX Any of numerous one-celled, aquatic organisms that have two dissimilar flagella and characteristics of both plants (algae) and animals (protozoans). Most are microscopic and marine. The group is an important component of phytoplankton in all but the colder seas, and it is an important link in the food chain. Dinoflagel- lates also produce part of the luminescence sometimes seen in the sea.

Under favourable conditions, dinoflagellate populations may reach 60 million organisms per litre of water. Such rapid growths, called blooms, result in the red tides that discolour the sea and poison fish and other marine animals. See also Ceratium.

dinosaur Any of the extinct reptiles that were the dominant land ani¬ mals during most of the Mesozoic Era (248-65 million years ago). The various species appeared at different times, and not all overlapped. The shape of the teeth reveal whether a given dinosaur was a carnivore or herbivore. Dinosaurs are classified as either ornithischians or saurischians, based on pelvic girdle structure. Most had a long tail, which they held straight out, apparently to maintain balance. Most, if not all, were egg layers. Some were probably warm-blooded. Dinosaur fossils have been found on every continent, including Antarctica. Most types of dinosaurs flourished until late in the Cretaceous Period (65 million years ago), then disappeared within the next million years. Two theories for the cause of this mass extinction, following some 140 million years of existence, are that mountain-building cycles altered habitat and changed climate or that an asteroid hit the Earth, resulting in immense dust clouds that blocked sunlight for several years. Birds are thought to be living descendants of the dinosaurs. See also carnosaur; sauropod.

Skeletons of an ornithischian dinosaur (Stegosaurus) and a saurischian dinosaur (Deinonychus). The skeleton of Stegosaurus shows a pelvic arrangement resembling that of birds, with a long ilium and a pubis having a short blade that extends back¬ ward into a long thin process lying below and parallel to the ischium. The pelvic girdle of Deinonychus shows the triangular outline formed by the ischium, pubis, and ilium characteristic of the saurischians.

Dinosaur National Monument National preserve, northwestern Colorado and northeastern Utah, U.S. It was set aside in 1915 to preserve rich fossil beds that include dinosaur remains. It was enlarged in 1938 and again in 1978 to its present 330 sq mi (855 sq km). It protects the canyons of the Green and Yampa rivers, which contain highly coloured geologic formations.

Dinwiddie \din-'wid-e\, Robert (b. 1693, Germiston, near Glasgow, Scot.—d. July 27, 1770, Clifton, Bristol, Eng.) British colonial adminis¬ trator. He entered government service in 1727 and was appointed surveyor general for the southern part of America (1739-51). As lieutenant gov¬ ernor of Virginia, he sent George Washington in 1753 to prevent the French from controlling the western frontier, an action that helped pre¬ cipitate the French and Indian War. He tried to obtain intercolonial coop¬ eration for the war effort, an issue taken up at the Albany Congress. In 1758 he returned to England.

Dingo ( Canis dingo , C. familiaris dingo, or C. lupus dingo).

G.R. ROBERTS

Diocletian ► Dior I 549

Diocletian y.dl-s-'kle-shonX Latin Gaius Aurelius Valerius Dio- cletianus orig. Diodes (b. ad

245, Salonae?, Dalmatia—d. 316,

Salonae) Roman emperor (284- 305). He was serving under the emperor Carinus (r. 283-285) when the co-emperor, Carinus’s brother Numerian, was killed. Diocletian’s army declared him emperor, but his domain was restricted to Asia Minor and possibly Syria. Carinus attacked Diocletian (285) but was assassi¬ nated before achieving victory, allowing Diocletian to become sole emperor. He sought to remove the military from politics and estab¬ lished a tetrarchy (four-ruler system) to spread his influence and combat rebellions throughout the empire.

Proclaiming himself and his corulers as gods, he added the trappings of a theocracy to the reign. His fiscal, administrative, and military reorga¬ nization laid the foundation for the Byzantine empire in the east and briefly strengthened the fading empire in the west. In 303-304 he issued four edicts decreeing the last great per¬ secution of Christians. He abdicated in 305.

Diocletian window Semicircular window divided into three lights (compartments) by two vertical mullions, with the central light usually wider than the two side lights. Its name comes from its use in the Baths of Diocletian in Rome (ad 302). It was revived in the 16th century by Andrea Palladio and others in the form of a window having an arched cen¬ tral light flanked by narrower, square-headed apertures, known as a Pal- ladian or Venetian window.

diode Electronic device that has two electrodes (anode and cathode) and that allows current to flow in only one direction, resisting current flow in the other. An applied voltage can cause electrons to flow in only one direction, from the cathode to the anode, and then back to the cathode through an external circuit. Diodes are used especially as rectifiers— which change alternating current into direct current —and to vary the amplitude of a signal in proportion to the voltage in a circuit, as in a radio or television receiver. The most familiar diodes are vacuum tubes and semi¬ conductor diodes. Semiconductor diodes, the simplest of semiconductor devices, consist of two electrodes and a sandwich of two dissimilar semi¬ conducting substances (a p-n junction). Such diodes form the basis for more complex semiconductor devices (including transistors) used in com¬ puters and other electronic equipment. Semiconductor diodes include light-emitting diodes and laser diodes; the latter emit laser light, useful for telecommunications via fibre optics and for reading compact discs.

Diogenes of Sinope \dI-'aj-3- l nez...s3- , n6-pe\ (b. Sinope,

Paphlygonia—d. c. 320 bc, probably Corinth) Greek philosopher, princi¬ pal member of the Cynics. He is credited by some with originating the Cynic way of life, but he himself acknowledged his debt to Antisthenes (c. 445-365 bc). He conveyed the Cynic philosophy by personal example rather than through any system of thought. He strove to destroy social conventions (including family life) as a way of returning to a “natural” life. To this end he lived as a vagabond pauper, sleeping in public build¬ ings and begging for food. He also advocated shamelessness (performing harmless unconventional actions), outspokenness, and training in auster¬ ity.

Diomede VdI-3-,med\ Islands Two islands in the Bering Strait. Lying about 2.5 mi (4 km) apart, they are separated by the U.S.-Russian bound¬ ary, which coincides with the International Date Line. The larger island, Big Diomede (Russian Ratmonov), belongs to Russia and is the site of an important weather station. To the east lies Little Diomede Island, a part of Alaska.

Diomedes \ 1 dI-3-'me- l dez\ Greek hero in the Trojan War. He was com¬ mander of 80 ships from Argos bringing soldiers to defeat Troy. His exploits included wounding the goddess Aphrodite, killing Rhesus and his Thracian followers, and stealing the Trojan Palladium (the sacred image of Athena that protected Troy). Aphrodite punished him by making his

wife unfaithful to him in his absence, and after the war he returned home to find his claim to the throne of Argos disputed. He then sailed to Italy and founded the colony of Argyripa (later Arpi) in Apulia.

Dionysia See Bacchanalia

Dionysius I or Dionysius the Elder (b. c. 430 bc —d. 367) Tyrant of Syracuse (405-367). He became ruler with Spartan help and retained power until his death, basing his strength on the support of his mercenary army. He held Carthaginian expansion on Sicily in check and hoped to acquire an empire in Greek Italy. Syracuse’s economy depended on war, and under Dionysius great advances were made in the technology of large-scale artillery and the manufacture of munitions. His disastrous third campaign against the Carthaginians resulted in the ceding of money and territory; he died during the next Carthaginian conflict.

Dionysius of Halicarnassus (fl. c. 20 bc) Greek historian and teacher of rhetoric. Born in Halicarnassus, Caria (Asia Minor), Dionysius went to Rome in 30 bc. His history of Rome, from its origins to the First Punic War, is written from a pro-Roman standpoint but carefully researched. It is, with Livy’s, the most valuable source for early Roman history. Its 20 books began to appear in 7 bc; the last 10 have been lost.

Dionysius the Areopagite X.ar-e-'a-po-jlt, .ar-e-'a-ps-.gfiA (fl. 1st century) Biblical figure, converted by St. Paul. His conversion at Athens is mentioned in Acts 17:34, and he acquired a posthumous reputation largely through confusion with later Christians similarly named. Around ad 500, a series of influential Greek treatises uniting Neoplatonism and Christian theology were forged in his name; the writer, probably a Syr¬ ian monk, is now known as Pseudo-Dionysius the Areopagite.

Dionysus \,dI-9-'nI-s9s\ Greek god of vegetation and fruitfulness, known especially as the god of wine and ecstasy. His Roman equivalent was Bacchus. His worship was introduced into Greece from Asia Minor, and he became one of the most important of all the Greek gods, while his cult remained associated with that of many Asiatic deities. A son of Zeus and (according to the standard tradition) Semele, he was brought up by the maenads, or bacchantes. The first creator of wine, he traveled widely teach¬ ing the winemaking art, with a following of satyrs, sileni (see satyr and silenus), and nymphs. He had the gift of prophecy and was received at Del¬ phi along with Apollo, though his principal oracle was at Thrace. Festivi¬ ties called Dionysia or (among the Romans) Bacchanalia were held in his honor; in their earlier years they were wild, ecstatic occasions, and they have often been the subject of artistic representation. Dionysus originally appeared as a bearded man, but later more often as a slim youth. His prin¬ cipal attribute was the thyrsus, a wand bound with vine leaves. The dithyramb, a choral hymn in his honor, is often seen as the basis of West¬ ern drama.

Diop VjopV Birago Ismael (b. Dec. 11, 1906, Dakar, French West Africa—d. Nov. 25, 1989, Dakar) Senegalese poet and recorder of tradi¬ tional Wolof folktales. A veterinarian and diplomat, he was active in the Negritude movement in the 1930s. His output of lyric poetry is small but the poetry is beautifully composed. His books containing tales told to him by his family’s griot include Tales of Amadou Koumba (1947) and Tales and Commentaries (1963).

diopside \dl-'ap-,sld\ Common silicate mineral in the pyroxene family. Diopside is a calcium and magne¬ sium silicate (CaMgSi 2 0 6 ) that occurs in metamorphosed siliceous limestones and dolomites, in skarns, and in igneous rocks. It is also found in small amounts in many chondritic meteorites. Clear specimens of good green colour are sometimes cut as gems.

Dior \'dy6r,\ English \de-'or,

'de-orV Christian (b. Jan. 21,

1905, Granville, France—d. Oct. 24,

1957, Montecatini, Italy) French fashion designer. He trained for the French diplomatic service, but in the financial crisis of the 1930s he began illustrating fashions for a weekly periodical. In 1942 he joined the Christian Dior, 1957. house of the Parisian designer encyclopedia britannica, inc.

Diocletian, detail of a bust in the Capi- toline Museum, Rome.

AUNARI/ART RESOURCE, NEW YORK

550 I diorite ► direct-mail marketing

Lucien Lelong. In 1947 he introduced his revolutionary “New Look,” which featured small shoulders, a natural waistline, and a voluminous skirt, a drastic change from the World War II look of padded shoulders and short skirts. In the 1950s the “sack,” or “H” line, became the char¬ acteristic silhouette of his designs. He was instrumental in commercial¬ izing Parisian fashion on a worldwide scale.

diorite Vdl-o-.rhA Medium- to coarse-grained igneous rock that com¬ monly is composed of about two-thirds plagioclase feldspar and one-third dark-coloured minerals, such as hornblende or biotite. Diorite has about the same structural properties as granite but, perhaps because of its darker colour and more limited supply, is rarely used as an ornamental building material. It is one of the dark gray stones that is sold commercially as “black granite.”

Dioscuri \ l dI-9s-'kyur-I, di-'as-kys-.rlN or Castor and Pollux (from Greek dioskouroi, “sons of Zeus”) Twin gods of ancient Greece and Rome. They aided shipwrecked sailors and accepted sacrifices for favor¬ able winds. Castor was mortal and Pollux was immortal; when Castor was killed, Pollux disowned his immortality to join his brother. Zeus later changed them into the constellation Gemini. They were believed to have aided the Romans in an important battle early in their history, and a temple in their honour was built in the Roman Forum.

dioxin \dl-'ak-s3n\ Aromatic compound, any of a group of contaminants produced in making herbicides (e.g., Agent Orange), disinfectants, and other agents. Their basic chemical structure consists of two benzene rings connected by a pair of oxygen atoms; when substituents on the rings are chlorine atoms, the molecules are particularly toxic. The best-known, usually called simply dioxin, is 2,3,7,8-tetrachlorodibenzo-/?-dioxin (2,3,7,8-TCDD). It is extremely stable chemically; it does not dissolve in water but dissolves in oils (and thus accumulates in body fat). The extent of its human toxicity is disputed and the subject of continuing research.

diphtheria \dif-'thir-e-9\ Acute infectious bacterial disease caused by Corynebacterium diphtheriae. The bacterium usually enters through the tonsils, nose, or throat and multiplies there, forming a thick membrane that adheres to the tissues and sometimes blocks the trachea, requiring emergency treatment.The bacteria produce a toxin that spreads to cause other symptoms, including fever, chills, sore throat, and lesions in heart muscle and peripheral nerve tissue that may cause death from heart fail¬ ure and paralysis. Diphtheria is treated with an antitoxin that neutralizes the toxin and produces long-term immunity. Vaccination has greatly reduced its occurrence in Europe and North America.

Diplodocus Xds-'pla-ds-kssX Genus of sauropod dinosaur found as fos¬ sils in Late Jurassic rocks of North America and related to Apatosaurus. Diplodocus and its relatives (diplodocids) were some of the longest land animals that ever lived, some approaching 100 ft (30 m). It had a long neck and extremely small brain and skull. Most diplodocids weighed about 30 tons, and some as much as 80 tons. It was formerly thought that Diplodocus may have spent a good deal of time in water, but fossil evi¬ dence indicates it moved freely on land, where it apparently fed on soft vegetation. It may be the most commonly displayed dinosaur.

diploidy See ploidy

diplomacy Art of conducting relationships for gain without conflict. It is the chief instrument of foreign policy. Its methods include secret nego¬ tiation by accredited envoys (though political leaders also negotiate) and international agreements and laws. Its use predates recorded history. The goal of diplomacy is to further the state’s interests as dictated by geog¬ raphy, history, and economics. Safeguarding the state’s independence, security, and integrity is of prime importance; preserving the widest pos¬ sible freedom of action for the state is nearly as important. Beyond that, diplomacy seeks maximum national advantage without using force and preferably without causing resentment.

diplomatic service See foreign service diplopia See double vision

Dipo Negoro Vde-po-ne-'gor-oV Pangeran (Prince) (b. c. 1785, Jogjakarta, Java—d. Jan. 8, 1855, Macassar [Ujung Pandang], Celebes) Javanese leader in the 19th-century conflict known to the West as the Java War (1825-30). He was the son of the ruler of Jogjakarta, a sultanate cre¬ ated in 1755 by a Dutch treaty that dismembered the once-powerful Jav¬ anese kingdom of Mataram. Dutch land reforms undercut the economic position of the Javanese aristocrats, and Dipo Negoro became the aristo¬

crats’ leader against the Dutch. The Javanese saw him as a “just prince” come to save the people, and the conflict itself was seen as a Muslim holy war against the infidels. For three years Dipo Negoro’s guerrilla forces had the upper hand, but the Dutch triumphed in the end. Dipo Negoro was arrested at the peace negotiations and died in exile.

dipole See electric dipole, magnetic dipole

dipper or water ouzel \'U-zsl\ Any of five songbird species in the genus Cinclus (family Cinclidae), noted for hunting insects by walking underwater in rushing streams. The species are widely distributed in Asia, Africa, Europe, and North and South America. Dippers are plump, stub-tailed birds, about 7 in. (18 cm) long, with a thrushlike bill and legs.

They are commonly blackish brown or dull gray. They nest in a dome of moss built in a crevice, often behind a waterfall. See also ouzel.

dipteran \'dip-ta-ren\ Any mem¬ ber of the more than 85,000 species in the insect order Diptera (the two¬ winged, or “true,” flies), character¬ ized by the use of only one pair of wings for flight and the reduction of the second pair of wings to knobs used for balance. Dipterans live in all habitats worldwide, including the subarctic and high mountains. They range in size from about 0.05 in. (1 mm) long (midges) to 3 in. (8 cm) long (robber flies). Dipteran larvae break down and redistribute organic materials, and both adults and larvae are a significant link in numerous food chains. Many species are annoying bloodsuckers, and several (e.g., housefly, mosquito, sand fly, tsetse fly) are vectors of disease. Other species cause great damage to agricultural crops. See also blowfly, crane fly, fruit fly, gnat, horsefly, leaf miner.

Dirac \di-'rak\, P(aul) A(drien) M(aurice) (b. Aug. 8, 1902, Bris¬ tol, Gloucestershire, Eng.—d. Oct. 20, 1984, Tallahassee, Fla., U.S.) English mathematician and theoretical physicist. His first major contri¬ bution (1925-26) was a general and logically simple form of quantum mechanics. About the same time, he developed ideas of Enrico Fermi, which led to the Fermi-Dirac statistics. He then applied Albert Einstein’s special theory of relativity to the quantum mechanics of the electron and showed that the electron must have spin of Vi. Dirac’s theory also revealed new states later identified with the positron. He shared the 1933 Nobel Prize for Physics with Erwin Schrodinger. In 1932 Dirac was appointed Luca¬ sian Professor of Mathematics at the University of Cambridge, a chair once occupied by Isaac Newton. Dirac retired from Cambridge in 1969 and held a professorship at Florida State University from 1971 until his death.

dire wolf Extinct wolf ( Canis dims ) that existed during the Pleistocene Epoch (1.8 million-10,000 years ago), probably the most common mam¬ malian species found preserved in the La Brea Tar Pits. It differed from the modern wolf in being larger and having a more massive skull, a smaller brain (and probably less intelligence), and relatively light limbs. The spe¬ cies was considerably widespread; skeletal remains have been found in Florida and the Mississippi valley in the U.S., as well as in the Valley of Mexico.

direct current (DC) Flow of electric charge that does not change direc¬ tion. Direct current is produced by batteries, fuel cells, rectifiers, and gen¬ erators with commutators. Direct current was supplanted by alternating current (AC) for common commercial power in the late 1880s because it was then uneconomical to transform it to the high voltages needed for long-distance transmission. Techniques developed in the 1960s overcame this obstacle, and direct current is now transmitted over very long dis¬ tances, though it must ordinarily be converted to alternating current for final distribution. For some uses, such as electroplating, direct current is essential.

direct-mail marketing Method of merchandising in which the sell¬ er’s offer is made through mass mailing of a circular or catalog or through a newspaper or magazine advertisement, and in which the buyer places an order by mail, telephone, or Internet. The rise of retail mail-order sell-

Eurasian dipper (Cinclus cinclus)

H.M. BARNFATHER-BRUCE COLEMAN INC.

directing ► Disney I 551

ing occurred in the late 19th century, when U.S. firms such as Sears, Roe¬ buck and Montgomery Ward built large businesses selling goods primarily to farmers. Its use has grown steadily since the introduction of comput¬ erized mailing lists after 1960; it is now employed by tens of thousands of firms, and it reaches virtually every consumer in the U.S.

directing Art of coordinating and controlling all elements in the stag¬ ing of a play or making of a film. Until the late 19th century, a theatrical director was usually the play’s leading actor or the company’s actor- manager. Today’s stage director combines elements such as actors, decor, costumes, and lighting to shape an imaginative interpretation of the play¬ wright’s script. The director must understand the art of acting and pro¬ vide guidance for the actors. The director also composes the “stage pictures,” the shifting arrangements of the actors and other elements on the stage. The film director combines the theatrical director’s responsi¬ bilities with the technical functions of cinematography, editing, and sound recording. See also actor-manager system; auteur theory.

Directoire style \de-rek-'twar\ Style of dress, furniture, and ornament popular in France during the Directory, 1795-99. Dress for men mixed the ancient and contemporary: high boots, vests, open coats, top hats. Women’s fashions featured dresses with long sleeves and V necklines, worn with ruffled caps. Directoire furniture and ornamentation were based on ancient Roman objects recently excavated at Pompeii.

Directory French Directoire \de-rek-'twar\ (1795-99) Government set up during the French Revolution by the Constitution of 1795. Legis¬ lative power was placed in the Council of Five Hundred and the Council of Ancients, while executive power was placed in a five-member Direc¬ tory. Though the Directors nominally inherited many of the powers of the Committee of Public Safety, they had no funds to finance their projects or courts to enforce their will. The regime was marked by administrative chaos and corruption and by the uprisings in the Vendee. It was overthrown in Napoleon’s Coup of 18-19 Brumaire.

dirigible See airship

Dirksen Vdork-sonX, Everett McKinley (b. Jan. 4, 1896, Pekin, Ill., U.S.—d. Sept. 7, 1969, Washington, D.C.) U.S. politician. After serving in World War I, he returned to Illinois to pursue business interests. He served in the U.S. House of Representatives (1932—48), where he voted against most New Deal measures and remained an isolationist until the U.S. entered World War II. He later served in the U.S. Senate (1950-69), becoming minority leader in 1959. He was noted for his oratorical style. Though a conservative, he helped secure passage of the Nuclear Test Ban Treaty, the Civil Rights Act, and the Voting Rights Act.

dirty sandstone See graywacke

disarmament Reduction in armaments by one or more nations. Arms reductions may be imposed by a war’s victors on the defeated (as hap¬ pened after Germany’s defeat in World War I). Bilateral disarmament agreements may apply to a specific area (such an agreement has kept the Great Lakes weapon-free since 1817). The term is most commonly used for multilateral reduction and limitation agreements, particularly in the context of nuclear weapons. See also arms control.

disc jockey (DJ) Person who plays recorded music on radio or tele¬ vision or at a nightclub or other live venue. Disc jockey programs became the economic base of many radio stations in the U.S. after World War II. The format generally involves one person, the disc jockey, introducing and playing phonograph records and chatting informally, usually extem¬ poraneously, in the intervals. Because popular DJs are in a position to influence public tastes, record companies have sometimes attempted to bribe them with money and gifts, known as “payola.”

Disciples of Christ Group of U.S. Protestant churches that originated in the frontier revivals of the early 19th century. Movements founded by Thomas and Alexander Campbell (1763-1854, 1788-1866) and Barton W. Stone (1772-1844) merged in 1832 and took the name Disciples of Christ. The new denomination grew rapidly. Its goal was to unite all Prot¬ estants on the basis of New Testament practices. The attempt failed, and the movement itself split into two major segments: the more conservative Churches of Christ (which rejects any innovation without New Testament precedent, including musical instruments in worship) and the Christian Church (Disciples of Christ). Other conservative congregations separated from the Christian Church (Disciples of Christ) in the 1920s; they estab¬ lished a separate annual gathering, the North American Christian Con¬

vention, in 1927. In 1985 the Disciples of Christ entered into an ecumenical partnership with the United Church of Christ. The common Disciples heritage is still manifest in the meetings of the World Conven¬ tion of Churches of Christ, organized in 1930.

disco Style of dance music that arose in the mid-1970s, characterized by hypnotic rhythm, repetitive lyrics, and electronically produced sounds. Disco (short for discotheque) evolved largely from New York City under¬ ground nightclubs, in which disc jockeys would play dance records for hours without interruption, taking care to synchronize the beats so as to make a seamless change between records. Artists such as Donna Summer, Chic, and the Bee Gees had many hits in the genre, which peaked with the release of the film Saturday Night Fever (1977). Disco faded quickly after 1980, but its powerful influence, especially its sequenced electronic beats, still continues to affect much of pop music.

discount rate or bank rate Interest rate charged by a central bank for loans of reserve funds to commercial banks and other financial inter¬ mediaries. The discount rate is one important indicator of the condition of monetary policy in an economy. Because raising or lowering the dis¬ count rate alters the rates that commercial banks charge on loans, adjust¬ ment of the discount rate is used as a tool to combat recession and inflation.

discovery In law, pretrial procedures providing for the exchange of information between the parties involved. Discovery may be made through interrogatories, written questions sent from one side to the other in an attempt to secure important facts. It also can be made through depo¬ sitions, whereby a witness is sworn and, in the presence of attorneys for both sides, is subjected to questions. (The written record of the proceed¬ ings also is called a deposition.) Other forms of discovery include an order of production and inspection, which compels the opposing party to pro¬ duce relevant documents or other evidence, and requests for medical examination in cases in which a party’s mental or physical condition is at issue.

discus throw Track-and-field sport of hurling for distance a disk¬ shaped object known as a discus. The discus is 8.6 in. (219 mm) in diam¬ eter and is thicker in the centre than at the perimeter; it must weigh at least 4.4 lbs (2 kg) for men’s events, 2.2 lbs (1 kg) for women’s. It is thrown by means of a whirling movement made by the athlete within a circle 8.2 ft (2.5 m) in diameter. The sport dates back to the ancient Greek Olympics.

disk, hard See hard disk disk flower See composite family diskette See floppy disk

dislocation Displacement of the bones of a joint. It disrupts the liga¬ ments, muscles, and capsule (encasing membrane) holding the joint in place. The joint, painful and tender, appears misshapen and swollen, with discoloration of the overlying skin. The patient cannot use the joint and often feels a grating or grinding sensation on trying to move it. The bones must be returned to their normal position (reduction) and the joint kept immobile until healed. Recurrent and congenital dislocations usually require surgical reconstruction.

Dismal Swamp or Great Dismal Swamp Wetland region, south¬ eastern Virginia and northeastern North Carolina, U.S. Despite much lum¬ bering and widespread destruction by fire, the area is still heavily wooded. About 30 mi (48 km) long and 10 mi (16 km) wide, it is home to many rare birds and numerous poisonous

snakes. Noted for its fishing and hunting, it is traversed by the Dismal Swamp Canal, part of the Atlantic Intracoastal Waterway.

Disney, Walt(er Elias) (b. Dec. 5, 1901, Chicago, Ill., U.S.—d. Dec. 15, 1966, Los Angeles, Calif.) U.S. animator and entertainment execu¬ tive. In the 1920s he joined with his brother Roy and his friend Ub Iwerks (1901-71) to establish an animation studio. Together they created Mickey Mouse, the cheerful rodent— customarily drawn by Iwerks, with Disney providing the voice—that

Walt Disney, 1950.

ALFRED EISENSTAEDT-TIME LIFE PICTURES/GETTY IMAGES

552 I Disney Co. ► distaff

starred in the first animated film with sound, Steamboat Willie (1928). The brothers formed Walt Disney Productions (later the Disney Co.) in 1929. Mickey Mouse’s instant popularity led them to invent other char¬ acters such as Donald Duck, Pluto, and Goofy and to make several short cartoon films, including The Three Little Pigs (1933). Their first full- length animated film, Snow White and the Seven Dwarfs (1937), was fol¬ lowed by classics such as Pinocchio (1940), Fantasia (1940), and Cinderella (1950). A perfectionist, an innovator, and a skilled business¬ man, Walt Disney maintained tight control over the company in both cre¬ ative and business aspects. He oversaw the company’s expansion into live-action films, television programming, theme parks, and mass mer¬ chandising. By his death in 1966, Disney had transformed the family entertainment industry and influenced more than one generation of Ameri¬ can children.

Disney Co. U.S. entertainment corporation. It was founded by Walt Disney and his brother Roy as Walt Disney Productions in 1929 to incor¬ porate their cartoon animation studio. It produced short and full-length animated cartoons in the 1930s and 1940s, then expanded in the 1950s to make nature documentaries and live-action films as well as television programs. The opening of the amusement parks Disneyland (1955) and Walt Disney World (1971; see Disney World and Disneyland) strengthened the company’s dominance of the family entertainment industry in the U.S. The company declined after Disney’s death in 1966 but was revitalized under new management in the 1980s. As the Walt Disney Co. it expanded its production units to include Touchstone Pictures and Miramax, makers of films for more mature audiences, and revitalized its animation divi¬ sion, producing films such as The Little Mermaid (1989) and Toy Story (1995), the first full-length computer-animated film. The company took an active role in reviving and commercializing New York City’s Times Square, including the recreation of some of its animated films, such as The Lion King (1994), as Broadway musicals. In 1994 it opened Celebra¬ tion, a planned community in central Florida. It acquired the ABC tele¬ vision network in 1996 and became the world’s largest media and entertainment corporation; it also operates the cable television Disney Channel. See also Michael Eisner.

Disney World and Disneyland Two theme parks built by the Walt Disney Co. (see Disney Co.), a U.S. corporation that became the best- known 20th-century purveyor of entertainment. Disneyland, an interac¬ tive, family-oriented fantasy environment that opened in Anaheim, Calif., in 1955, was Walt Disney’s response to typical amusement parks, which entertained children but not their parents. The park, which has architec¬ ture that is a blend of futurism and nostalgic 19th-century reproductions, has different sections devoted to specific themes. Walt Disney World opened near Orlando, Fla., in 1971. Besides containing Epcot Center (an idealized city), Disney-MGM Studios, and the Magic Kingdom and Ani¬ mal Kingdom theme parks, Disney World was the first amusement park to incorporate hotels (including two designed by Michael Graves) and sports and other recreational facilities into its master plan. In the late 20th century new Disney theme parks also opened in Paris and Tokyo.

disorderly conduct Conduct likely to lead to a disturbance of the public peace or that offends public decency. It has been held to include the use of obscene language in public, fighting in a public place, block¬ ing public ways, and making threats. Statutes against disorderly conduct must identify the specific acts that constitute it. The offense usually car¬ ries minor penalties.

dispersion Any phenomenon associated with the propagation of indi¬ vidual waves at speeds that depend on their wavelengths. Wavelength determines the speeds at which waves travel through media. This varia¬ tion in speed causes radiation to separate into components that have dif¬ ferent frequencies and wavelengths. For example, when a beam of white light is sent through a glass prism, refraction causes the beam to disperse into an array of its component colours of light, producing a rainbowlike effect.

displacement activity Performance by an animal of an act inappro¬ priate for the stimulus or stimuli that evoked it. It usually occurs when an animal is torn between two conflicting drives, such as fear and aggres¬ sion. Displacement activities often consist of comfort movements (e.g., grooming, scratching).

display behaviour Ritualized activity by which an animal conveys specific information. The best-known displays are visual, but others rely on sound, smell, or touch. Agonistic (aggressive) displays make it unnec¬

essary to chase intruders from a territory or for animals to injure each other in competition for mates. One type of defensive display deceives predators or lures them away from vulnerable young. See also birdsong; COURTSHIP BEHAVIOUR.

disposable income Portion of an individual’s income over which the recipient has complete discretion. To assess disposable income, it is nec¬ essary to determine total income, including not only wages and salaries, interest and dividend payments, and business profits, but also transfer income such as social-security benefits, pensions, and alimony. Obliga¬ tory payments, including personal income taxes and compulsory social- insurance contributions, must be subtracted. Disposable income may be used for consumption or saving.

Dispur \dis-'pur\ City, capital of Assam state, northeastern India. Fol¬ lowing the administrative reorganization of the region in 1972, Dispur, a suburb of Guwahati, became the state capital.

Disraeli \diz-'ra-le\, Benjamin, earl of Beaconsfield (b. Dec. 21, 1804, London, Eng.—d. April 19, 1881, London) British politician and author who was twice prime minister (1868, 1874-80). Of Italian-Jewish descent, he was baptized a Christian as a child, which enabled his future career, because until 1858, practitioners of Judaism were excluded from Parliament. He first made his mark as a writer with Vivian Grey (1826— 27); later novels included Coningsby (1844) and Sybil (1845). He was elected to Parliament as a Conservative in 1837. In 1845 he made a series of brilliant speeches against Sir Robert Peel’s decision to repeal the Corn Laws, which helped him to become leader of the Conservatives. He served three stints as chancellor of the Exchequer (1852, 1858-59, 1865-68) and played a prominent role in passing the Reform Bill of 1867. He was prime minister briefly in 1868, then returned in his second ministry (1874-80) to promote social reform. An advocate of a strong foreign policy, he secured a triumph for imperial prestige with his acquisition of Suez Canal shares and won concessions for England at the Congress of Berlin. A trusted friend of Queen Victoria, he introduced a bill conferring on her the title Empress of India. After the Conservatives were defeated in 1880, he kept the party leadership and finished his political novel Endymion (1880).

dissociation Breaking of a chemical compound into simpler constitu¬ ents as a result of added energy, as in the case of gaseous molecules dis¬ sociated by heating; also, the effect of a solvent on a dissolved polar compound (electrolyte), as in the case of an inorganic salt, such as sodium chloride, dissolved in water. All electrolytes dissociate into ions to a greater or lesser extent in polar solvents (in which the molecules are elec¬ tric dipoles). The degree of dissociation can be used to determine the equi¬ librium constant. Dissociation is used to explain electrical conductivity and many other properties of electrolytic solutions.

dissociative identity disorder formerly multiple personality disorder Rare condition indicated by the absence of a clear and com¬ prehensive identity. In most cases two or more independent and distinct personality systems develop in the same individual. Each personality may alternately inhabit the person’s conscious awareness to the exclusion of the others, but one is usually dominant. The various personalities typi¬ cally differ from one another in outlook, temperament, and body language and might assume different first names. The condition is generally viewed as resulting from dissociative mental processes—that is, the splitting off from conscious awareness and control of thoughts, feelings, memories, and other mental components in response to situations that are painful, disturbing, or somehow unacceptable to the person experiencing them. Treatment is aimed at integrating the disparate personalities back into a single and unified personality.

dissonance See consonance and dissonance dissonance, cognitive See cognitive dissonance

distaff Device used in hand spinning in which individual fibres are drawn out of a mass of prepared fibres held on a stick (the distaff), twisted together to form a continuous strand, and wound on a second stick (the spindle). It is most often used for making linen; wool does not require a distaff (see carding). The first stage in mechanizing spinning was to mount the spindle horizontally in bearings to rotate with a large hand-driven wheel; the distaff, carrying the mass of fibre, was held in the left hand, and the spinning wheel slowly turned with the right. The Saxon, or Sax¬ ony, wheel incorporated a bobbin on which the yarn was wound continu¬ ously; the distaff holding the raw fibre became a stationary vertical rod, and the wheel was activated by a foot treadle, freeing both the operator’s

distance formula ► diverticulum I 553

hands. From 17th-century England, the word distaff became a synonym for maternal as most spinning was done by women in their homes. See also DOMESTIC SYSTEM.

distance formula Algebraic expression that gives the distances between pairs of points in terms of their coordinates (see coordinate sys¬ tem). In two- and three-dimensional Euclidean space, the distance formu¬ las for points in rectangular coordinates are based on the Pythagorean theorem. The distance between the points (a,b) and ( c,d) is given by V(a - c ) 2 + (b - d) 2 . In three dimensional space, the distance between the points (a, b, c ) and ( d , e, f) is “n J(a - d) 2 + (b — e ) 2 + (c - f) 2 .

distemper Viral disease in two forms, canine and feline. Canine dis¬ temper is acute and highly contagious, affecting dogs, foxes, wolves, mink, raccoons, and ferrets. Most untreated cases are fatal. Infected ani¬ mals are best treated with prompt injections of serum globulins; second¬ ary infections are warded off by antibiotics. Immunity can be conferred by vaccination. Feline distemper causes a severe drop in the number of the infected cat’s white blood cells. It rarely lasts more than a week, but the mortality rate is high. Vaccines offer effective immunity.

disthene See kyanite

distillation Vaporization of a liquid and subsequent condensation of the resultant GAS back to liquid form. It is used to separate liquids from non¬ volatile solids or solutes (e.g., water from salt and other components of seawater) or to separate two or more liquids with different boiling points (e.g., alcohol from fermented beers and wines). Many variations have been devised for industrial applications. An important one is fractional distillation, in which vapour from a heated liquid mixture is contacted by a series of trays and condensed liquid as it rises through a vertical col¬ umn. The most volatile fraction of the mixture emerges from the top of the column, while less volatile fractions are withdrawn at lower points. In petroleum refining, this method is very efficient for removing naphtha, kerosene, and gas oils from crude oil.

A laboratory distillation apparatus demonstrating desalination of water. In the distil¬ lation flask, salt water is boiled to produce water vapour, or steam, while the salt remains in the liquid solution. The vapour rises through the top of the flask and passes into the condenser, which consists of a glass tube within a larger tube. Cold water flows through the space between the tubes, cooling the vapour in the inner tube so that it condenses and flows into the receiving flask.

distilled liquor Alcoholic beverage obtained by distillation from wine or other fermented fruit juice or from various cereal grains that have first been brewed. The essential ingredient is usually a natural sugar or a starchy substance that may be easily converted into a sugar. The distil¬ lation process is based on the different boiling points of water (212 °F [100 °C]) and alcohol (173 °F [78.5 °C]). The alcohol vapours that arise while the fermented liquid boils are trapped and recondensed to create a liquid of much greater alcoholic strength. The resultant distillate is matured, often for several years, before it is packaged and sold. See also aquavit; brandy; gin; liqueur; rum; vodka; and whiskey.

distribution See frequency distribution, normal distribution

distributive law One of the laws relating to number operations. In sym¬ bols, it is stated; a{b + c) = ab + ac. The monomial factor a is distributed, or separately applied, to each term of the polynomial factor b + c, resulting in the product ab + ac. It can also be stated in words: The result of first adding several numbers and then multiplying the sum by some number is the same as first multiplying each separately by the number and then adding the products. See also associative law; commutative law.

District Court, U.S. See United States District Court

District of Columbia Federal district of the U.S. Coextensive with the city of Washington, it is bounded by Maryland and Virginia. Originally 100 sq mi (259 sq km), the territory was authorized by Congress in 1790 and granted by Maryland and Virginia; it now occupies 68 sq mi (176 sq km). The site was chosen by Pres. George Washington and became the seat of the federal government by 1800. Part of the district (Alexandria, Va.) was retroceded to Virginia in 1847. The slave trade was prohibited in the District in 1850 and slavery was abolished in 1862. The territorial government was abolished in 1874 in favour of government by a com¬ mission appointed by the president. Residents were granted suffrage in national elections in 1961 by the 23rd Amendment to the U.S. Constitu¬ tion. The mayor-council form of government was established in 1967. Originally appointees of the president, the mayor and councilors became elected officials in 1973 and received local legislative powers in 1974.

dithyramb \'dith-i-,ram(b)\ Choric poem, chant, or hymn of ancient Greece. Dithyrambs were sung by revelers at the festival in honour of Dionysus. The form originated about the 7th century bc in extemporane¬ ous songs of banqueters; it was a recognized literary genre by the end of the 6th century bc. Dithyrambs were composed by Arion and Pindar, among others. By c. 450 bc the form was in decline; most dithyrambs were bombastic and turgid.

Differs von Dittersdorf Vdit-ors-.dorft, Carl orig. Carl Differs (b.

Nov. 2, 1739, Vienna, Austria—d. Oct. 24, 1799, Rothlhotta Castle, Neu- hof, Bohemia) Austrian composer. A violin prodigy, he served as kapell¬ meister at the court of the prince-bishop of Breslau (1770-95). Though ennobled by the empress in 1773, he apparently declined the offer of the post of kapellmeister at the imperial court in Vienna. Extremely prolific, he wrote some 120 symphonies, some 40 concertos (many for violin), sacred choral works, and many chamber pieces. Most important are some 40 stage works, particularly his singspiels, including Doctor und Apotheker (1786) and Die Liebe im Narrenhause (1787).

diuretic \,dl-yur-'e-tik\ Any drug that increases the flow of urine from the body. Diuretics promote removal of excess water, salts, poisons, and metabolic wastes to help relieve edema, kidney failure, or glaucoma. Most types act by decreasing the amount of fluid that is reabsorbed by the kid¬ ney’s nephrons and passed back into the blood. Diuretics that allow the body to retain potassium are used for patients with hypertension or conges¬ tive HEART FAILURE.

Divali or Diwali Vdo-'wa-le, d3-'va-le\ In Hinduism, a five-day religious festival in autumn. It honors Lakshmi, goddess of wealth, or, in Bengal, the goddess Kali. During its celebration, earthenware lamps are lit and placed on the parapets of houses and temples or set adrift on rivers and streams. The fourth day of the festival marks the start of a new year, a time of gift-giving, visiting friends, decorating homes, and wearing new clothes. Divali is celebrated by Jains and Sikhs as well.

diver See loon

divergence In mathematics, a differential operator applied to a three- dimensional vector-valued function. The result is a function that describes a rate of change. The divergence of a vector v is given by

div v =

dvi

dll . d_y dz

in which v l5 v 2 , and v 3 are the vector components of v, typically a veloc¬ ity field of fluid flow.

diverticulum X.dl-vor-'ti-kyo-bmX Small pouch or sac formed in the wall of a major organ, usually the esophagus, small intestine, or large intes¬ tine (the most frequent site of problems). In the large intestine, feces pushed into a pouch can make it bulge out from the colon wall, a con¬ dition known as diverticulosis, which has no symptoms. In the more seri-

554 I divertimento ► Dixieland

ous condition called diverticulitis, those sacs become inflamed, causing pain and tenderness, chills, and sometimes fever. Mild cases need only bed rest and antibiotics. In severe cases, perforation or rupture of the colon wall at the diverticulum can cause peritonitis. Rupture may require colos¬ tomy. Meckel diverticulum, a congenital malformation of the upper intes¬ tine that causes bleeding and inflammation, may require surgical removal.

divertimento Xdi-.vor-ti-'men-toN Eighteenth-century chamber music genre consisting of several movements, often of a light and entertaining nature, for strings, winds, or both. Though the name was applied (c. 1750-1800) to a confusingly varied range of works, it almost always referred to pieces with a single instrument to a part; this could include string quartets and even keyboard sonatas.

dividend Individual share of earnings distributed among stockholders of a corporation or company in proportion to their holdings. Usually paid in cash, dividends may also be distributed in the form of additional shares of stock. Preferred stockholders receive a preferential dividend, usually at a fixed rate; common stockholders get a portion of what remains after payment of the dividends on preferred stock.

dividing engine Machine used to mark off equal intervals accurately, usually on precision instruments. Georg Friedrich von Reichenbach (1772-1826), a German maker of astronomical instruments, designed an early dividing engine, and Jesse Ramsden (1735-1800), a British pioneer in the design of precision tools, designed dividing engines of great accu¬ racy for both circles and straight lines and produced highly accurate sex¬ tants, theodolites (see surveying), and vertical circles for astronomical observatories.

divination Practice of discerning the hidden significance of events and foretelling the future. Divination is found in all societies, ancient and modern, though methods vary. In the West, psychics claim innate ability to predict the future, and horoscopes, palm reading, and tarot cards are popular methods of divination. Other methods involve or have involved interpreting dreams, discovering omens in natural events, reading the entrails of animals, casting lots, and consulting oracles. Divination has long been viewed as the province of specially gifted persons, such as prophets, shamans, and magicians. See also astrology.

Divine, Father orig. George Baker (b. 1880?, Georgia?, U.S.—d. Sept. 10, 1965, Philadelphia, Pa.) U.S. religious leader. Reportedly born on a plantation, he began preaching in 1899 in the South and later in Bal¬ timore, Md., as “The Messenger.” He settled in New York City in 1915 and adopted the name Major J. Devine (later altered to Father Divine). In 1919 he established his first communal settlement in Sayville on Long Island, and he founded the Peace Mission movement. His predominantly black following expanded rapidly in the 1930s and ’40s, and his settle¬ ments, called “heavens,” eventually numbered about 170. He taught his followers to renounce personal property, and the strict moral code he preached included celibacy and a ban on alcohol and tobacco. Many of his followers, called “angels,” believed him to be God.

divine kingship Religio-political concept that views a ruler as an incarnation, manifestation, mediator, or agent of the sacred. In some non¬ literate societies, members view their rulers or chiefs as inheritors of the community’s own magical power. The ruler may exercise this power either malevolently or benevolently, but he is usually responsible for influ¬ encing the weather and the land’s fertility to ensure the harvest necessary for survival. In other societies, particularly those of ancient China, the Middle East, and South America, the ruler was identified with a particu¬ lar god or as a god himself; in Japan, Peru (among the Inca), Mesopot¬ amia, and the Greco-Roman world, the ruler was regarded as the son of a god. In either case—whether the ruler embodies his own magical power or that of the community—the ruler protects the community from enemies and generally feeds and cares for his people. A third form of divine king- ship, one practiced in Europe, is that of the ruler as mediator or execu¬ tive agent of a god. In this form it is the institution of kingship, more than an individual ruler, that bears the mark of the sacred.

diving Sport of plunging into water, usually headfirst and often follow¬ ing the execution of one or more acrobatic maneuvers. It emerged as a competitive sport in the late 19th century and became part of the Olym¬ pic Games in 1904. Dives are performed from a firm platform 5 or 10 m (16.4 or 32.8 ft) above the water, or from a springboard 1 or 3 m (3.3 or 9.8 ft) above the water. In Olympic contests, only the 10-m platform and 3-m springboard are used. Contestants are required to do certain dives,

as well as dives of their own choice, each rated according to its degree of difficulty. Judges score each dive, and the total score is multiplied by the degree of difficulty.

diving duck Any duck that obtains its food by diving to the bottom in deep water rather than by dabbling in shallows (see dabbling duck). Div¬ ing ducks prefer marine environments and are popularly called either bay ducks or sea ducks. Bay ducks (tribe Aythyini, family Anatidae), includ¬ ing canvasback, redhead, scaup, and allied species, are found more fre¬ quently in estuaries and tidal lagoons than on the open sea. Sea ducks (20 species in tribes Mergini and Somateriini) include the bufflehead, eiders, goldeneye, mergansers, oldsquaw, and scoters; some are also or mainly found on inland waters.

division of labour Specialization in the production process. Complex jobs can usually be less expensively completed by a large number of people each performing a small number of specialized tasks than by one person attempting to complete the entire job. The idea that specialization reduces costs, and thereby the price the consumer pays, is embedded in the principle of comparative advantage. Division of labour is the basic principle underlying the assembly line in mass production systems. See Emile Durkheim.

divorce Dissolution of a valid marriage, usually freeing the parties to remarry. In societies in which religious authority is strong and the reli¬ gion holds that marriage is indissoluble (e.g., Roman Catholicism, Hindu¬ ism), divorce may be difficult and rare. In the U.S. at the beginning of the 21st century there was about one divorce for every two marriages. The rate of divorce in the U.S. is greater than it is in most other Western coun¬ tries, though divorce rates climbed in those countries in the last decades of the 20th century. The most common grounds for divorce are absence from the marital home, drug or alcohol addiction, adultery, cruelty, con¬ viction of a crime, desertion, insanity, and nonsupport. See also annul¬ ment.

Diwali See Divali

Dix, Dorothea (Lynde) (b. April 4, 1802, Hampden, District of Maine, Mass., U.S.—d. July 17, 1887, Trenton, N.J.) U.S. social reformer on behalf of the mentally ill. She opened a school for girls in Boston in 1821, and in 1841 she began teaching Sunday school in a jail, where she was distressed to see the mentally ill imprisoned with criminals. For 18 months she toured mental institutions, and in 1843 she reported their deplorable conditions to the Massachusetts legislature. After improve¬ ments were made, she expanded her campaign to other states. Through her work, special mental hospitals were built in 15 states and in Canada.

Dix, Otto (b. Dec. 2, 1891, Untermhaus, Thuringia, Ger.—d. July 25, 1969, Singen, Baden-Wiirttemberg,

W.Ger.) German painter and print- maker. He studied at the academies of Diisseldorf and Dresden and experimented with Impressionism and Dada before arriving at Expressionism with a nightmarish personal vision of contemporary social reality, depict¬ ing the horrors of war and the depravities of a decadent society with great emotional effect. He was appointed professor at the Dresden Academy in 1926 and elected to the Prussian Academy in 1931. His anti¬ military works aroused the wrath of the Nazi regime and he was dis¬ missed from his academic posts in 1933. His later work was marked by religious mysticism. See also Neue Sachlichkeit.

Dixiecrat or States' Rights Democrat In the U.S., member of a right-wing Democratic splinter group in the 1948 election. Organized by Southerners who objected to the Democrats’ civil rights program, the Dixiecrats met in Birmingham, Ala., and nominated Gov. Strom Thurmond of South Carolina for president. He received more than one million votes in the 1948 election and won four states.

Dixieland Jazz played by a small ensemble featuring collective and solo improvisation. The term is often ascribed especially to the New Orleans

"Parents of the Artist," oil on canvas by Otto Dix, 1921; in the Offentliche Kunstsammlung, Basel, Switzerland

COURTESY OF THE OFFENTLICHE KUNSTSAMMLUNG AND THE EMANUEL HOFFMAN-STIFTUNG, BASEL, SWITZ; PHOTOGRAPH, HANS HINZ

Dixon ► DNA computing I 555

pioneers of jazz, although many critics of popular music believe the term better describes the music of a later wave of white Chicago musicians including Jimmy McPartland, Bud Freeman, and Frank Teschemacher. The earliest jazz ensembles grew out of the ragtime and brass bands of New Orleans, incorporating elements of the blues. In early jazz ensembles, such as those led by King Oliver and Jelly Roll Morton, the trumpet or comet plays the melody, with clarinet and trombone providing accompa¬ niment. The tension created by soloists contrasts with the release of ensemble refrains. It is played with a distinctive two-beat rhythm, result¬ ing in a joyous cacophony at fast tempos or slow, mournful dirges. Dix¬ ieland groups usually include banjo, tuba, and drums.

Dixon, Joseph (b. Jan. 18, 1799, Marblehead, Mass., U.S.—d. June 15, 1869, Jersey City, N.J.) U.S. inventor and manufacturer. Largely self- taught, Dixon began his pioneering industrial use of graphite in 1827 with the manufacture of lead pencils, stove polish, and lubricants. He discov¬ ered that graphite crucibles withstood high temperatures, and he secured patents on graphite crucibles for making steel and pottery. He established a crucible steelworks in Jersey City in 1850. He also experimented with photography and photolithography and devised a technique for printing banknotes in colour to prevent counterfeiting.

Dixon, Willie orig. William James Dixon (b. July 1, 1915, Vicks¬ burg, Miss., U.S.—d. Jan. 29, 1992, Burbank, Calif.) U.S. musician who influenced the emergence of electric blues and rock music. In 1936 Dixon moved from his native Mississippi to Chicago, won an Illinois Golden Gloves boxing championship, and began selling his songs. He played double bass in several bands before joining Chess Records. His lively compositions, which he sold for as little as $30, included “Little Red Rooster,” “You Shook Me,” and “Back Door Man”; many were later recorded by Muddy Waters, Elvis Presley, and the Rolling Stones. Dixon toured widely throughout the U.S. and Europe.

Djakarta See Jakarta

Djibouti \ji-'bu-te\ officially Republic of Djibouti, formerly (1967-

77) French Territory of the Afars and Issas \a-'far...e-'sa, a-'farz...e-'saz\ Country, eastern Africa, on the Gulf of Aden at the entrance

to the Red Sea. Area: 8,950 sq mi (23,200 o 25 so mi SC 1 km). Population (2005 est.): 476,700.

6 25 ' so 75 km Capital: Djibouti. Roughly half of the

people are Issas and related Somali clans; Afars are about one-third; the balance includes Yemeni Arabs and Europeans, mostly French. Languages: French, Arabic (both official). Religion: Islam (predominantly Sunni). Currency: Djibouti franc. Djibouti is divided into three principal regions: the coastal plain, the volcanic plateaus in the country’s south and centre,

and the mountain ranges in the north, reaching 6,654 ft (2,028 m) high at Mount Moussa (Mousa). The land is primarily desert—hot, dry, and desolate; virtually none is arable. Djibouti has a developing market economy that is based almost entirely on trade and commercial services, centring on Djibouti city. The country is a republic with one legislative house; its head of state and government is the president. Settled by the Arab ancestors of the Afars, it was later populated by Somali Issas. In ad 825 Islam was brought to the area by missionaries. Arabs controlled the trade in this region until the 16th century; it became a French pro¬ tectorate in the 19th century. It was made a French overseas territory in 1946, assumed the name French Territory of the Afars and Issas in 1967, and gained its independence in 1977. In the late 20th century it received refugees from the Ethiopian-Somali war and from civil conflicts in Eri¬ trea. From the 1990s the country experienced political unrest.

Djibouti City (pop., 1995 est.: 383,000), major port, and capital of Dji¬ bouti. Located on the southern shore of the Gulf of Tadjoura in the Gulf of Aden, it was founded by the French in 1888 and made the capital of French Somaliland in 1892. Linked by rail to Addis Ababa in 1917, it was made a free port in 1949. The economic life of both the city and the nation depends on the city’s function as a transshipment point, especially between Ethiopia and the Red Sea trade. Built on three level areas linked by jetties, the city has a mixture of ancient and modem architecture. Drought and war during the 1980s and early ’90s brought many refugees to Djibouti from Somalia and Ethiopia, swelling its population.

Djilas Vji-las\, Milovan (b. June 12, 1911, Podbisce, Montenegro—d. April 20, 1995, Belgrade, Serbia) Yugoslav politician and political writer. His opposition to Yugoslavia’s royalist dictatorship led to a prison term (1933-36). He joined the Yugoslav Communist Party’s central commit}tee in 1938 and its politburo in 1940. In World War II he played a major role in the partisan resistance to the Germans. In 1953 he became president of the Federal People’s Assembly, but his criticism of the party and calls for liberalization soon led to his ouster from all political posts by Tito. He was later arrested several times after his books criticizing communism, including The New Class (1957), were published in the West.

Dmitry, False or Pseudo-Demetrius Any of three pretenders to the Muscovite throne who, during the Time of Troubles, claimed to be Ivan IV’s child Dmitry Ivanovich, who had died mysteriously while still a child, possibly murdered at the order of Boris Godunov. The first False Dmitry challenged Godunov’s right to the throne and was proclaimed tsar in 1605. In 1606 he was murdered by Vasily Shuysky (1552-1612), who succeeded him. Rumors spread that Dmitry had survived, and a sec¬ ond pretender gained a large following before being killed in 1610. A third False Dmitry appeared in 1611, gaining the allegiance of the Cos¬ sacks and the inhabitants of Pskov, but he was executed in 1612.

DNA or deoxyribonucleic Xde-'ak-si-.ri-bo-nyu-'kle-ik, de-'ak- si-.ri-bo-nyu-'kla-ikA acid One of two types of nucleic acid (the other is RNA); a complex organic compound found in all living cells and many viRUSes. It is the chemical substance of genes. Its structure, with two strands wound around each other in a double helix to resemble a twisted ladder, was first described (1953) by Francis Crick and James D. Watson. Each strand is a long chain (polymer) of repeating nucleotides: adenine (A), guanine (G), cytosine (C), and thymine (T). The two strands contain complementary information: A forms hydrogen bonds (see hydrogen bonding) only with T, C only with G. When DNA is copied in the cell, the strands separate and each serves as a template for assembling a new complementary strand; this is the key to stable heredity. DNA in cells is organized into dense protein-DNA complexes (see nucleoprotein) called chromosomes. In eukaryotes these are in the nucleus, and DNA also occurs in mitochondria and chloroplasts (if any). Prokaryotes have a single cir¬ cular chromosome in the cytoplasm. Some prokaryotes and a few eukary¬ otes have DNA outside the chromosomes in plasmids. See also Rosalind Franklin; genetic engineering; mutation; Maurice Wilkins. See illustration on following page.

DNA computing Form of computing in which DNA molecules are used instead of digital logic circuits. The biological cell is regarded as an entity that resembles a sophisticated computer. The four amino acid bases that are constituents of DNA, traditionally represented by the letters A, T, C, and G, are used as operators, as the binary digits 0 and 1 are used in computers. DNA molecules are encoded to a researcher’s specifications and then induced to recombine (see recombination), resulting in trillions of

556 I DNA fingerprinting ► Doctorow

A. B.

1 2 ^ 3 4 5

DNA double helix. A. Molecular model of DNA. The molecules include (1) hydro¬ gen, (2) oxygen (3) carbon and nitrogen in the linked nitrogenous bases, (4) car¬ bon in the sugar deoxyribose, and (5) phosphorus. B. Schematic representation of DNA. The twisted ladder shape consists of (6) nitrogenous base pairs joined by hydrogen bonds, on (7) a sugar-phosphate backbone.

“calculations” simultaneously. The field is in its infancy and its implica¬ tions are only beginning to be explored. See also quantum computing.

DNA fingerprinting Method developed by the British geneticist Alec Jeffreys (born 1950) in 1984 for isolating and making images of sequences of DNA. The procedure consists of obtaining a sample of cells contain¬ ing DNA (e.g., from skin, blood, or hair), extracting the DNA, and puri¬ fying it. The DNA is then cut by enzymes, and the resulting fragments of varying lengths undergo procedures that permit them to be analyzed. The pattern of fragments is unique for each individual. DNA fingerprinting is used to help solve crimes and determine paternity; it is also used to locate gene segments that cause genetic diseases, to map the genetic material of humans (see Human Genome Project), to engineer drought-resistant plants (see genetic engineering), and to produce biological drugs from genetically altered cells.

Dnieper River \'ne-por\ Russian Dnepr Xdo-'nyeprA ancient Borys- thenes. River, eastern central Europe. One of the longest rivers in Europe, it rises west of Moscow and flows south through Belarus and Ukraine, emptying into the Black Sea after a course of 1,420 mi (2,285 km). More than 300 hydroelectric plants operate in the Dnieper basin, and it has several huge dams. Navigable for about 1,042 mi (1,677 km) during the 10 months of the year when it is not frozen, it is an important shipping artery for eastern Europe.

Dniester River \'ne-stor\ Russian Dnestr \do-'nyestr 3 \ ancient Tyras. River, southern central Europe. Rising on the northern side of the Carpathian Mtns., it flows south and east for 840 mi (1,352 km) to the Black Sea near Odessa. It is the second-longest river in Ukraine and the main water artery of Moldova. It is navigable for 750 mi (1,200 km).

Dnipropetrovsk \d9-,nye-pr9-pe-'tr6fsk\ formerly (1783-1926) Eka- terinoslav \i- l ka-ti-'re-no- l slaf\ City (pop., 2001: 3,567,600), south- central Ukraine. Located on the Dnieper River, it was founded in 1783 and named for Catherine the Great; it grew after the railroad arrived in the 1880s. In 1926 the Soviets gave it its current name. A railway junction

and a centre of the wheat trade, it has developed into one of the largest industrial cities of Ukraine, with a huge iron and steel industry. It is the site of institutes of higher education, and its cultural amenities include several theatres.

Doberman pinscher Vdo-bar-mon-'pin-choiA Breed of working dog developed in Apolda, Germany, by Louis Dobermann, a dog-pound keeper, in the late 19th century. This sleek, agile, powerful dog stands 24-28 in. (61-71 cm) high and weighs 60-88 lbs (27^10 kg). It has a short, smooth black, blue, fawn, or red coat, with rust markings on the head, throat, chest, tail base, and feet. Dobermans have a reputation for fearlessness, alertness, loyalty, and intelligence. They have been used in police and military work, as watchdogs, and as guide dogs for the blind.

Doblin Vdoe-.blenV Alfred (b. Aug. 10, 1878, Stettin, Ger.—d. June 26, 1957, Emmendingen, near Freiburg im Breisgau, W.Ger.) German novelist and essayist. He studied medicine at the Universities of Berlin and Freiburg, specializing in psychiatry. His first novel. The Three Leaps of Wang-Lun (1915), describes the quashing of a rebellion in China. His best-known work, Berlin Alexanderplatz (1929; film, 1931; adapted for television, 1980), is written in an Expressionist vein and dramatizes the miseries of working-class life in a disintegrating social order. His Jewish ancestry and socialist views compelled him to leave Germany upon the Nazi takeover, and he fled to France (1933) and then to the U.S. (1940), resettling in Paris in the early 1950s.

Dobrovsky Vdo-brof-skeV Josef (b. Aug. 17, 1753, Gyarmat, Hung.—d. Jan. 6, 1829, Brno, Moravia, Austrian Empire) Czech linguist. He was ordained a priest in 1786, but after 1791 noble patronage allowed him to devote himself to scholarship in Prague. His textual criticism of the Bible led him to study Old Church Slavonic and then the Slavic lan¬ guages as a group. An influential scholar of the Czech language and its literature, he published such works as History of the Bohemian Language and Literature (1792). His grammar of Czech, Learning System of the Bohemian Language (1809), helped standardize literary Czech, and his grammar of Old Church Slavonic (1822) laid the foundation of compara¬ tive Slavic LINGUISTICS.

dobsonfly Any insect of the family Corydalidae with four net-veined wings, found in North and South America, Asia, Australia, and Africa. The species Corydalus cornutus has a wingspread of about 5 in. (13 cm), and the male has very large jaws (mandibles) of about 1 in. (2.5 cm) or more. Females lay eggs near streams. Larvae live in the streams and, with their strong biting mouthparts, are ferocious predators on other aquatic insects and small invertebrates. Sometimes called hellgrammites or toe- biters, they can inflict painful bites on humans; they are eaten by fish, especially bass, and are used as bait by fishermen.

Dobzhansky \dob-'zhan-ske\, Theodosius orig. Feodosy Grig- orevich Dobrzhansky (b. Jan. 25, 1900, Nemirov, Ukr., Russian Empire—d. Dec. 18, 1975, Davis, Calif., U.S.) Ukrainian-born U.S. geneticist and evolutionist. He immigrated in 1927 to the U.S., where he taught at the California Institute of Technology, Columbia University, and Rockefeller University. He laid the groundwork for a theory combining Darwinian evolution and Mendelian genetics by changing the then com¬ monly held view that natural selection produced something close to the best of all possible results and that changes would be rare and slow and not apparent over one life span. He observed extensive genetic variabil¬ ity in wild populations of Drosophila, and he found that in a given popu¬ lation some genes would regularly change in abundance with the seasons of the year.

dock Any coarse weedy plant of the genus Rumex, in the buckwheat fam¬ ily, that has a long taproot and is sometimes used as a potherb. Most docks are native to Europe but naturalized throughout North America. Examples include curly dock ( R. crispus) and bitter dock (R. obtusifolius ). The early basal leaves of patience-dock ( R. patientia ) are sometimes used in salads. The common weed R. acetosa is known variously as dock, common sor¬ rel, or garden sorrel. See also sorrel.

Doctorow Vdak-t9-.ro\, E(dgar) L(aurence) (b. Jan. 6, 1931, New York, N.Y., U.S.) U.S. novelist. Doctorow worked as an editor and has since taught at colleges and universities. His best-selling novels have often focused on the working class and the dispossessed of earlier decades in the U.S. The Book of Daniel (1971) concerned the Rosenberg spy case. Ragtime (1975; film, 1981) incorporates actual early 20th-century Ameri¬ can figures. Loon Lake (1980), World’s Fair (1985), and Billy Bathgate

Doctors' Plot ► Doesburg I 557

(1989; film, 1991) examine the Great Depression and its aftermath. City of God (2000), concerns the efforts of a New York City Episcopal min¬ ister to renew his faith.

Doctors' Plot (1953) Alleged conspiracy of prominent Soviet medical specialists to murder leading government and party officials. In January 1953, the Soviet press reported that nine doctors, at least six of them Jews, had been arrested and confessed their guilt. Because of Joseph Stalin’s death in March, no trial occurred. Pravda later announced that the charges against the doctors were false and their confessions obtained by torture. In his secret speech at the Communist Party’s Twentieth Congress, Nikita Khrushchev asserted that Stalin intended to use the doctors’ trial to launch a massive party purge.

Doctors Without Borders French Medecins Sans Frontieres

\mad- , sa n -sa I1 -fro n - , tyer\ (MSF) World’s largest independent international medical relief agency. It was established by a group of French physicians in 1971. It aids victims of armed conflict, epidemics, and natural and man-made disasters and helps others whose lack of health care is due to geographic remoteness or ethnic or political marginalization. Teams pro¬ vide primary health care, perform surgery, vaccinate children, rehabilitate hospitals, operate emergency nutrition and sanitation programs, and train local medical staff. Operating independently of governments, the organi¬ zation depends on volunteer health professionals (more than 2,000 annu¬ ally) and private donations. It received the 1999 Nobel Peace Prize.

doctrine of the affections German Affektenlehre Aesthetic theory of music in the Baroque period. Under the influence of Classical rhetoric, late Baroque theorists and composers held that music is capable of arousing a variety of specific emotions in the listener, and that, by employing the proper musical procedure or device, the composer could produce a particular involuntary emotional response in his audience. By the end of the 17th century, individual movements were customarily orga¬ nized around a single emotion, resulting in the lack of strong contrasts and the repetitive rhythms characteristic of Baroque music. Several attempts at systematic lists of the emotional effects of different scales and figures were made, but to no general agreement.

Doctrine of the Mean See Zhong yong

rootlike organs called haustoria that penetrate the tissue of a host plant and may kill it. Dodder can do great damage to crops of clover, alfalfa, flax, HOPS, and beans. The best control is to remove the plant from fields by hand and to prevent its accidental introduction.

Dodge, Mary Mapes orig. Mary Elizabeth Mapes (b. Jan. 26, 1831, New York, N.Y., U.S.—d. Aug. 21, 1905, Onteora Park, N.Y.) U.S. author. She began writing children’s stories when she was suddenly wid¬ owed with two small sons. Her first collection, Irvington Stories (1864), was followed by Hans Brinker; or, The Silver Skates (1865), which became a children’s classic. In 1873 she was named editor of the new children’s magazine St. Nicholas', its success stemmed from her high standards, which attracted such writers as Mark Twain, Louisa May Alcott, Robert Louis Stevenson, and Rudyard Kipling.

Dodge, William E(arl) (b. Sept. 4, 1805, Hartford, Conn., U.S.—d. Feb. 9, 1883, New York, N.Y.) U.S. mining entrepreneur. He was a dry- goods merchant in Hartford, Conn., before founding the metal dealership Phelps, Dodge & Co. with his father-in-law, Anson G. Phelps, in 1833. They soon established a prosperous metal-importing business. Dodge made numerous other investments in timberland, mills, and iron and cop¬ per mines. After purchasing the Copper Queen mine in Arizona in 1882, the company became a major U.S. mining concern. Further acquisitions and diversifications have made Phelps Dodge Corp. one of the world’s largest copper producers.

dodo Extinct flightless bird ( Raphus cucullatus ) of Mauritius, first seen by Portuguese sailors about 1507.

Humans and the animals they intro¬ duced had exterminated the dodo by 1681. It weighed about 50 lbs (23 kg) and had blue-gray plumage, a big head, a 9-in. (23-cm) blackish bill with a reddish hooked tip, small use¬ less wings, stout yellow legs, and a tuft of curly feathers high on its rear end. The Reunion solitaire ( R. soli- tarius), also driven to extinction, may have been a white version of the dodo. Partial museum specimens and skeletons are all that remain of the dodo.

Dodoma \do-'do-ma\ City (pop.,

1995 est.: 189,000), Tanzania. Des¬ ignated the national capital since 1974, it awaits complete transfer of official functions from Dar es Salaam, the current capital. Located in a sparsely populated agricultural region at an elevation of 3,720 ft (1,135 m), it is a market centre for the surround¬ ing area. Industries produce wood and furniture, beverages, processed food, soap, and oil.

Dodona \do-'do-no\ Sanctuary of the Greek god Zeus, located at Epirus. Mentioned by Homer, it was the site of an oracle, where messages came through the rustling of leaves or other natural sounds. There was also a large bronze gong that vibrated in the breeze.

Doe, Samuel K(anyon) (b. May 6,1950/51, Tuzon, Liberia—d. Sept. 9/10, 1990, Monrovia) Liberian soldier and head of state (1980-90). A member of the Krahn ethnic group, Doe led a coup in 1980 that overthrew Pres. William R. Tolbert (b. 1913—d. 1980). He suspended Liberia’s con¬ stitution until 1984, and in 1985 he won a presidential election widely denounced as fraudulent. His regime was considered corrupt and brutal, and his life was continually threatened by assassination attempts. In the civil war that broke out in 1989, Doe was captured and killed.

Doenitz, Karl See Karl Donitz

Doesburg Vdiis-.biergV Theo van orig. Christian Emil Maries Kupper (b. Aug. 30, 1883, Utrecht, Neth.—d. March 7, 1931, Davos, Switz.) Dutch painter, decorator, and art theorist. Originally involved in theatre, in 1900 he began painting under the influence of Post-Impressionism and Fauvism. After meeting the painter Piet Mondrian in 1915, he turned to geometric abstraction. He was instrumental in founding the De Stijl group and the avant-garde periodical De Stijl. His advocacy of the geo¬ metric style was well received at the Bauhaus, where he taught briefly and influenced Le Corbusier, Walter Gropius, and Ludwig Mies van der Rohe. In

Restoration of a dodo (Raphus cuculla¬ tus)

COURTESY OF THE PEABODY MUSEUM OF NATURAL HISTORY, YALE UNIVERSITY

documentary Fact-based film that depicts actual events and persons. Documentaries can deal with scientific or educational topics, can be a form of journalism or social commentary, or can be a conduit for propa¬ ganda or personal expression. The term was first coined by Scottish-bom filmmaker John Grierson to describe fact-based features such as Robert Flaherty’s Nanook of the North (1922). Grierson’s Drifters (1929) and Pare Lorentz’s The Plow That Broke the Plains (1936) influenced docu¬ mentary filmmaking in the 1930s. During the World War II era documen¬ tary filmmaking was a valuable propaganda tool used by all sides. Leni Riefenstahl contributed to the Nazi propaganda efforts in the 1930s; the U.S. made films such as Frank Capra’s series Why We Fight (1942-45); and Britain released London Can Take It (1940). Cinema verite documen¬ taries, which gained notoriety in the 1960s, emphasized a more informal and intimate relationship between camera and subject. Television became an important medium for documentary films with goals that were more journalistic (such as CBS’s Harvest of Shame [I960]) and educational (such as Ken Burns’s Civil War [1990]).

documentary theatre See The¬ atre of Fact

dodder Any of the leafless, twin¬ ing, parasitic vines (see parasitism) that make up the genus Cuscuta (family Cuscutaceae), containing more than 150 species found throughout temperate and tropical regions. The stringlike stems may be yellow, orange, pink, or brown. Many species have been introduced with their host plants into new areas. Dod¬ ders contain no chlorophyll, instead absorbing water and food through

Dodder (Cuscuta gronovii)

RUSS KINNE-PHOTO RESEARCHERS

558 I dog ► Dolin

1926 Doesburg wrote his manifesto, “De Stijl”, and in 1930 he moved to Paris and opened a studio, which became the focus of the movement.

dog Any member of the canine genus Canis, particularly the domestic species, Canis familiaris. Domestic dogs seem to have decended from the wolf or a wolflike ancestor. Dogs were apparently the first animals to be domesticated, and domestication seems to have begun in various parts of the world at roughly the same time. Selective breeding by humans has resulted in myriad domestic breeds that vary widely in size (from the tiny Chihuahua to the huge mastiff), physical form (e.g., the short-legged dachs¬ hund and the flat-faced bulldog), coat texture and length (e.g., the sleek Doberman pinscher and the long-haired Afghan hound), and behavioral patterns (e.g., sporting dogs, toy dogs, and working dogs). The American Kennel Club now recognizes almost 150 breeds; other clubs, such as the United Kennel Club, recognize many more.

dog salmon See chum salmon Dog Star See Sirius

dogbane family Family Apocynaceae, of the gentian order, with about 1,000 member species of trees, shrubs, woody vines, and herba¬ ceous plants, found mostly in the tropics and subtropics. Dogbanes have milky, often poisonous juice and usually clustered, showy flowers. Gar¬ den ornamentals include periwinkle, oleander, yellow oleander ( Thevetia ), frangipani, Natal plum ( Carissa ), and crepe jasmine ( Tabernaemontana coronaria). Some species are African succulents. Arrow poisons are obtained from many dogbanes, and the poisonous alkaloids of some spe¬ cies are used in medicines.

doge \'doj\ (Venetian Italian: “duke”) Highest official of the republic of Venice in the 8th— 1 8th century. The office originated when the city was nominally subject to the Byzantine empire and became permanent in the 8th century. The doge was chosen from among the ruling families of Ven¬ ice and held office for life. He held extensive power, as evidenced by the rule of Enrico Dandolo (r. 1192-1205), though from the 12th century the aristocracy placed limits on the doge’s authority. Under Francesco Fos- cari (r. 1423-57), Venice undertook the first conquests of the Italian main¬ land. The last doge was deposed when Napoleon conquered northern Italy in 1797.

Dogen \'do-gen\ (b. Jan. 19, 1200, Kyoto, Japan—d. Sept. 22, 1253, Kyoto) Japanese Buddhist who introduced Soto Zen to Japan from China. Orphaned at age 7, he became a monk at 13. He studied in China under the Zen master Rujing (1223-27), and he also studied with Eisai. He returned to Japan and taught Zen meditation, spending his last years at Eihei Temple, which he founded.

dogfish Any of several species of small sharks. The spiny dogfish (Squalus acanthias, family Squalidae) has a sharp spine in front of each of its two dorsal fins. It is abundant along northern Atlantic and Pacific coasts. It is gray with white spots, about 2-4 ft (60-120 cm) long, and often found in schools. It preys on fishes and invertebrates and often steals bait and damages fishing nets. It yields liver oil or is ground for fertil¬ izer. Other well-known species are the spotted dogfishes (family Scyliorhinidae), which are sold as food, and the smooth hound or smooth dogfish {Mustelus canis, family Triakidae), one of the most common sharks on the U.S. Atlantic coast. See also bowfin.

Dogon \'do-,gan\ People of the central plateau region of Mali, around Bandiagara. Their language is of uncertain affinity within the Niger- Congo languages. Numbering about 450,000, the Dogon are mainly an agricultural people. Their distinctive villages are composed of elaborate mud buildings, often built on cliff faces. In addition to their characteris¬ tic architecture, the Dogon are known for their fine wood sculptures and masks, metalwork, and leatherwork.

dogsled racing Sport of racing sleds pulled by dogs over snow-covered cross-country courses. It developed from a traditional Eskimo method of transportation. Modem sleds are usually of wood (ash) construction, with leather lashings and steel- or aluminum-covered runners. Sled dogs are usually Eskimo dogs, Siberian huskies, Samoyeds, or Alaskan malamutes; teams typically consist of 4-10 dogs. The course is usually 12-30 mi (19-48 km) long, though some, including the Iditarod, are considerably longer.

dogtooth violet Any of the approximately 20 species of spring¬ blooming plants that make up the genus Erythronium, in the lily family, all native to North America except for the purple- or pink-flowered dogtooth violet of Europe ( E . dens-canis). The nodding flowers, usually one to a

plant or in small clusters, range in colour from white to purple. The two leaves, borne at the base of the plant, often are covered with white or brown spots. The common dogtooth violet of North America, E. ameri- canum, has yellow flowers and brown-mottled leaves. Several species are grown as rock-garden ornamentals.

dogwood Shrubs, trees, and herbaceous plants of the genus Cornus, in the dogwood family (Cornaceae), found in temperate and warm tem¬ perate zones and on tropical moun¬ tains. The family is noted for its woody ornamental species native to both coasts of North America and to eastern Asia and Europe. Some members, such as the flowering dog¬ wood ( Cornus florida), are chiefly ornamental; the European cornelian cherry (C. mas), also an ornamental, has edible fruit; others yield wood for furniture. In the flowering dog¬ woods, flowers are small; the con¬ spicuously expanded structures are coloured bracts that surround the cluster of true flowers.

Doha Vdo-hoX Arabic Al- Dawhah \ad-'dau-h9\ City (pop.,

1997: 264,009), capital of Qatar.

Located on the east coast of the Qatar Peninsula, it contains about three-fifths of the country’s population. Long a centre of pirate activity in the Persian Gulf, Doha was a small vil¬ lage when it became the capital of newly independent Qatar in 1971. The city has been thoroughly modernized. Its Government House (1969) was built on reclaimed waterfront land; its water supply is obtained by distill¬ ing seawater. The deepwater port, built in the 1970s, accommodates oceangoing vessels.

Doherty, Peter Charles (b. Oct. 15, 1940, Australia) Australian immunologist and pathologist. He earned a Ph.D. at the University of Edinburgh. With Rolf M. Zinkernagel, he found that T cells from mice infected with a meningitis virus destroyed virus-infected cells only from the same strain of mice, and he showed that T cells must recognize two signals on an infected cell—one from the virus and one from the cell’s own antigens—to destroy it. For the new understanding of general cel¬ lular immune mechanisms enabled by their research, the two men shared a 1996 Nobel Prize.

Dole, Bob in full Robert Joseph Dole (b. July 22, 1923, Russell, Kan., U.S.) U.S. politician. Seriously wounded while fighting in World War II, he recovered from near-total paralysis but permanently lost the use of his right arm and hand. He returned to Kansas, earned a law degree, and held state elective office as a Republican before serving in the U.S. House of Representatives (1961-69) and the Senate (1969-96). He was the running mate of Pres. Gerald R. Ford in 1976. In 1984 Dole became Republican Party leader in the Senate, and he twice served as majority leader (1984-86, 1994-96). After clinching his party’s nomination for president in 1996, he retired from the Senate to devote himself wholly to the campaign. He was defeated in the election by Democrat Bill Clinton. His wife, Elizabeth Hanford Dole (bom 1936), ran unsuccessfully for the Republican nomination in 2000 but was elected to the U.S. Senate from North Carolina in 2002.

Dole, Sanford Ballard (b. April 23, 1844, Honolulu, Hawaiian Islands—d. June 9, 1926, Honolulu) Hawaiian politician. The son of U.S. missionaries, he served in Hawaii’s legislature (1884-87) and on its supreme court (1887-93). He led the committee formed by local sugar interests that overthrew Queen Liliuokalani ( 1 893) and sought annexation by the U.S.; he then served as the first president of the Republic of Hawaii (1894-1900). Though U.S. Pres. Grover Cleveland demanded the queen’s restoration, Dole pressed successfully for annexation (1900) and after¬ ward served as governor of the Territory of Hawaii (1900-03). He later became a federal district judge (1903-15).

dolerite See diabase

Dolin, Sir Anton orig. Sydney F.P.C. Healey-Kay (b. July 27, 1904, Slinfold, Sussex, Eng.—d. Nov. 25, 1983, Paris, Fr.) British dancer

Flowers of flowering dogwood (Cornus florida)

J.C. ALLEN AND SON

doline ► domain name I 559

and choreographer. In 1921 he joined the Ballets Russes, where he created leading roles as a soloist. In the 1930s and 1940s he helped form several ballet companies; in 1949 he and his partner Alicia Markova founded the forerunner of London’s Festival Ballet, of which he was artistic director and premier dancer until 1961. He created leading roles in Le Train bleu. Job, and Bluebeard, choreographed works such as Capriccioso (1940), The Romantic Age (1942), and Variations for Four (1957), and wrote sev¬ eral books on dance.

doline See sinkhole

doll Small-scale figure of a human being or animal, used especially as a child’s plaything. The doll is perhaps humankind’s oldest toy. Some ancient dolls may have served reli¬ gious or magical functions—as do voodoo (see vodun) dolls in modern times. Dolls were buried in children’s graves in Egypt, Greece, and Rome and in early Christian catacombs. In Europe dolls have been commer¬ cially manufactured since about the 16th century. Doll heads were made of wood, terra-cotta, alabaster, and wax, while the bodies were made of carved wood or leather stuffed with sawdust. In about 1820 glazed porce¬ lain (Dresden) doll heads and unglazed bisque (ceramic) heads became popular. These were sup¬ planted in the 20th century by molded plastic. In Japan, dolls are used as traditional festival figures. In India, elaborately dressed dolls were given to child brides by both Hindus and Muslims. Today both antique and modern dolls are often collected.

Dollar Diplomacy U.S. foreign policy created by Pres. William H.

Taft to ensure financial stability in a region in exchange for favourable treatment of U.S. commercial interests.The policy grew out of Pres. The¬ odore Roosevelt’s peaceful intervention in the Dominican Republic, where U.S. loans had been exchanged for the right to choose the head of cus¬ toms (the country’s major revenue source). Taft’s secretary of state. Phi¬ lander Knox carried out Dollar Diplomacy in Central America (1909) and China (1910). Pres. Woodrow Wilson repudiated the policy in 1913. The term has become a disparaging reference to the manipulation of foreign affairs for economic ends.

Dollfuss \'dol-,fUs\, Engelbert (b. Oct. 4, 1892, Texing, Austro- Hungarian Empire—d. July 25,1934, Vienna, Austria) Austrian politician. He rose rapidly in Austrian politics to become chancellor in 1932. Opposed to the Nazis, he welcomed Benito Mussolini as an ally, convert¬ ing Austria virtually into an Italian satellite state. In 1933 he abolished the parliament and established an authoritarian regime based on conser¬ vative Roman Catholic and Italian Fascist principles. In 1934 after para¬ military groups loyal to him crushed Austria’s Social Democrats, he issued a new constitution establishing a dictatorship. Germany soon incited the Austrian Nazis to civil war, and Dollfuss was assassinated in a raid on the chancellery.

Dollond Vdal-sndX, John and George (respectively b. June 10, 1706, London, Eng.—d. Nov. 30, 1761, London; b. Jan. 25, 1774, London—d. May 13, 1852, London) British optical scientists. John devel¬ oped an achromatic (non-colour-distorting) refracting telescope and a prac¬ tical heliometer (a telescope that measures the Sun’s diameter and the angles between celestial bodies). His grandson George worked most of his life for the family firm of instrument makers, inventing various pre¬ cision instruments used in astronomy, geodesy, and navigation. His micrometer made of rock crystal was used by astronomers; his atmospheric recorder simultaneously measured and recorded on paper tape tempera¬ ture, atmospheric pressure, wind speed and direction, evaporation, and electrical phenomena.

dolmen Vdol-monN Prehistoric monument usually consisting of several large stone slabs set edgewise in the earth to support a flat stone roof, all

covered by a mound of earth that in most cases has weathered away.

Designed as a burial chamber, the structure is typical of the Neolithic Period in Europe. Dolmens, though found as far east as Japan, are mainly confined to western Europe and northern Africa. See also megalith;

MENHIR.

Dolmetsch \'dal- l mech\ / (Eu- gene) Arnold (b. Feb. 24, 1858,

Le Mans, France—d. Feb. 28, 1940,

Haslemere, Surrey, Eng.) French- bom British music scholar and performer. He moved to England after studying violin with Henri Vieuxtemps (1820-81). There he began col¬ lecting, repairing, and learning to play old instruments. He built copies of old lutes, clavichords, harpsichords, and recorders, ultimately involv¬ ing his wife and children in the performance and promulgation of early music. His Interpretation of Music of the 17th and 18th Centuries (1915) was highly influential, and he is regarded as the father of the 20th-century early music revival.

dolomite Type of limestone, the carbonate fraction of which is domi¬ nated by the mineral dolomite, calcium magnesium carbonate CaMg(C0 3 ) 2 . The carbonate mineral dolomite occurs in marbles, talc schists, and other magnesium-rich metamorphic rocks. It occurs in hydro- thermal veins, in cavities in carbonate rocks, and less often in various sedimentary rocks as a cement. It is most common as a rock-forming mineral in carbonate rocks.

Dolomites Vdo-lo-.mltsV Italian Alpi Dolomitiche Val-pe-do-lo-'me- te-ke\ Mountain group, northern Italian Alps. Including a number of impressive peaks, 18 of which rise to more than 10,000 ft (3,050 m), the range and its characteristic rock are named for the 18th-century French geologist Dieudonne Dolomieu, who made the first scientific study of the region. The mountains are formed of light-colored dolomitic limestone, which erosion has carved into grotesque shapes. Popular with tourists and mountain-climbers, the area has a number of resort towns.

dolphin One of a large group of small, gregarious, streamlined whales or one of two species of oceanic sport and food fishes. Mammalian dolphins are small toothed whales, usually with a well-defined, beaklike snout. (They are sometimes called porpoises, but that name is properly reserved for a blunt-snouted whale family.) The common dolphin ( Del- phinus delphis) and the bottlenose dolphin, both of the family Delphin- idae, are found widely in warm tem¬ perate seas, though some inhabit tropical rivers. Most of the 32 del- phinid species are marine; gray, blackish or brown above and pale below; and about 3-13 ft (1^1 m) long. River dolphins (family Pla- tanistidae; five species) live mainly in fresh water in South America and Asia. One of the two fish species,

Coryphaena hippuras (family Coryphaenidae), also called mahimahi and dorado, is a popular fish of tropical and temperate waters worldwide. The pompano dolphin (C. equiselis ) is similar. See also killer whale.

Domagk \'do-,mak\ / Gerhard (b. Oct. 30, 1895, Lagow, Branden¬ burg, Ger.—d. April 24, 1964, Burgberg, near Konigsfeld, W.Ger.) Ger¬ man bacteriologist and pathologist. While director of the Bayer Laboratory for Experimental Pathology and Bacteriology, Domagk noticed the antibacterial action of a dye, Prontosil red, against strepto¬ coccal infection in mice. Found to be an effective treatment in humans, Prontosil became the first sulfonamide drug. Awarded a Nobel Prize in 1939, Domagk was unable to accept it at the time because of Nazi policy. He also was active in research on tuberculosis and cancer.

domain name Address of a computer, organization, or other entity on a TCP/IP network such as the Internet. Domain names are typically in a