Britannica Concise 2005

diabase or dolerite Fine- to medium-grained, dark gray to black intrusive igneous rock. Diabase is one of the dark rocks known commer¬ cially as “black granite.” It is extremely hard and tough and is commonly quarried for crushed stone, under the name “trap.” Chemically and min- eralogically, diabase closely resembles the volcanic rock basalt, but it is generally somewhat coarser grained.

diabetes insipidus X.dl-o-'be-tez-in-'si-po-dssX Endocrine disorder causing extreme thirst and excessive production of very dilute urine, apparently due to lack of antidiuretic hormone (vasopressin, which regu¬ lates the kidney’s water conservation and urine production) or failure of the kidney tubules to respond to it. Injections of synthetic vasopressin are effective if the hormone is lacking but not if the response is absent. Dis¬ orders of the hypothalamus are one cause of diabetes insipidus.

diabetes mellitus Vmel-ot-osX Disorder of insufficient production of or reduced sensitivity to insulin. Insulin, synthesized in the islets of Langerhans (see Langerhans, islets of), is necessary to metabolize glucose. In diabetes, blood sugar levels increase (hyperglycemia). Excess sugar is excreted in the urine (glycosuria). Symptoms include increased urine out¬ put, thirst, weight loss, and weakness. Type 1, or insulin-dependent dia¬ betes mellitus (IDDM), an autoimmune disease in which no insulin is produced, must be treated by insulin injections. Type 2, or non-insulin- dependent diabetes mellitus (NIDDM), in which tissues do not respond to insulin, is linked to heredity and obesity and may be controlled by diet; it accounts for 90% of all cases, many of which go undiagnosed for years. Untreated diabetes leads to accumulation of ketones in the blood, followed by acidosis (high blood acid content) with nausea and vomiting and then coma. Careful attention to content and timing of meals, with periodic

checking of blood sugar, may manage diabetes. If not, injected or oral insulin is necessary. Complications, including heart disease, diabetic ret¬ inopathy (a leading cause of blindness), kidney disease, and nerve disor¬ ders, especially in the legs and feet, account for most deaths. Degree of blood-sugar control does not always correlate with progression of com¬ plications. Gestational diabetes may occur as a complication of pregnancy.

diagenesis Sum of all processes, chiefly chemical, that produce changes in a sediment after its deposition but before its final lithification. Usually, not all the minerals in a sediment are in chemical equilibrium, so changes in interstitial water composition or in temperature or in both will lead to chemical alteration of one or more of the minerals present. Diagenesis is considered a relatively low-pressure, low-temperature alter¬ ation process that involves such processes as cementation, reworking, replacement, crystallization, and leaching.

Diaghilev Vde-'a-go-.lefV, Sergey (Pavlovich) (b. March 31, 1872, Novgorod province, Russia—d.

Aug. 19, 1929, Venice, Italy) Rus¬ sian impresario, founder-director of the Ballets Russes. After studying law at the University of St. Petersburg (1890-96), he cofounded and edited (1899-1904) the avant-garde maga¬ zine Mir Iskusstva (“World of Art”).

He then left Russia for Paris to present productions of Russian bal¬ let and opera, to wide acclaim. In 1909 he established the Ballets Russes, in which he achieved a stun¬ ning synthesis of dance, art, and music by bringing together superb choreographers, dancers, composers, and artists and set designers. He led the company until his death.

diagnosis Identification of a dis¬ ease or disorder. Diagnosis requires a medical history (including family history), a physical examination, and usually tests and diagnostic proce¬ dures (e.g., BLOOD ANALYSIS, DIAGNOSTIC imaging). A list of possible causes— the differential diagnosis—is devel¬ oped and then narrowed down by further tests that eliminate or support specific possibilities.

diagnostic imaging or medical imaging Use of electromagnetic radiation to produce images of internal body structures for diagnosis. X-rays have been used since 1895. Denser tissues, such as bones, absorb more X-rays and show as lighter areas on X-ray film. A contrast medium can be used to highlight soft tissues in still X-ray pictures or can be fol¬ lowed on X-ray motion-picture films as it moves through the body or part of the body to record body processes. In computed axial tomography, X-rays are focused on specific tissue planes, and a series of such parallel “slices” of the body are processed by computer to produce a 3-D image. The risks of X-ray exposure are reduced by more precise techniques using lower doses and by use of other imaging techniques. See also angiocardiography; angiography; magnetic resonance imaging; nuclear medicine; positron emission tomography; ultrasound.

dial gauge Any of a number of deviation-type gauges that indicate the amount by which an object being gauged deviates from the standard. This deviation is usually shown in units of measurement, but some gauges show only whether the deviation is within a certain range. They include dial indicators, in which movement of a gauging spindle deflects a pointer on a graduated dial; wiggler indicators, used by machinists to centre or align work in machine tools; comparators, or visual gauges; and air gauges, used to gauge holes of various types.

dialect Variety of a language spoken by a group of people and having features of vocabulary, grammar, and/or pronunciation that distinguish it from other varieties of the same language. Dialects usually develop as a result of geographic, social, political, or economic barriers between groups of people who speak the same language. When dialects diverge to the point that they are mutually incomprehensible, they become languages

Bayt ul-Mukarram mosque and shop¬ ping mall, Dhaka, Bangladesh.

FREDERIC OHRINGER-NANCY PALMER AGENCY/EB INC.

Sergey Diaghilev, c. 1916.

DANCE COLLECTION, THE NEW YORK PUBLIC LIBRARY AT LINCOLN CENTER, ASTER, LENOX AND TILDEN FOUNDATIONS

© 2006 Encyclopaedia Britannica, Inc.

dialectical materialism ► diary I 541

in their own right. This was the case with Latin, various dialects of which evolved into the different Romance languages. See also koine.

dialectical materialism Philosophical approach expressed through the writings of Karl Marx and Friedrich Engels, and later by Georgy Ple- khanov, Vladimir Ilich Lenin, and Joseph Stalin, the official philosophy of communism. Its central tenet, borrowed from Hegelianism, is that all his¬ torical growth, change, and development results from the struggle of opposites. (In philosophical terms, a thesis is opposed by its antithesis, which results in a synthesis.) Specifically, it is the class struggle—the struggle between the capitalist and landowning classes, on the one hand, and the proletariat and peasantry, on the other—that creates the dynamic of history. The laws of historical dialectics are seen to be so powerful that individual leaders are of little historical consequence. Originally con¬ ceived as operating primarily in the social, economic, and political realm, the principle was extended in the 20th century to the scientific realm as well, with major effects on Soviet science. Marx and Engels stated their philosophical views mainly in the course of polemics and brief historical studies; there is no systematic exposition of dialectical materialism.

dialysis \dl-'a-b-s9s\ In chemistry, separation of suspended colloidal (see colloid) particles from dissolved ions or small molecules via their unequal rates of diffusion through pores of semipermeable membranes (e.g., parchment, collodion, cellophane). A slow process, dialysis may be accel¬ erated by heating or by applying an electric field if the particles are charged.

dialysis \dl-'a-b-s3s\ or hemodialysis \ I he-mo-dI-'a-b-s9s\ Process of removing blood from a patient with kidney failure, purifying it with a hemodialyzer (artificial kidney), and returning it to the bloodstream. Many substances (including urea and inorganic salts) in the blood pass through a porous membrane in the machine into a sterile solution; particles such as blood cells and proteins are too large to pass. This process controls the acid-base balance of the blood and its content of water and dissolved materials.

diamagnetism Kind of magnetism characteristic of materials that line up at right angles to a nonuniform magnetic field and that partly expel from their interior the magnetic field in which they are placed. In most mate¬ rials, the magnetic fields of the electrons balance each other and add up to zero. However, when placed in an external magnetic field, the inter¬ action of this field with the electrons induces an internal field in the oppo¬ site direction. The substance can then be weakly repelled by magnetic poles. Examples of diamagnetic substances include bismuth, antimony, SODIUM CHLORIDE, GOLD, and MERCURY.

diamond Mineral composed of pure carbon, the hardest naturally occurring substance known and a valuable gemstone. Diamonds are formed deep in the Earth by tremendous pressures and temperatures over long periods of time. In the crystal structure of diamond, each carbon atom is linked to four other, equidistant, carbon atoms. This tight crystal struc¬ ture results in properties that are very different from those of graphite, the other common form of pure carbon. Diamonds vary from colourless to black and may be transparent, translucent, or opaque. Most gem diamonds are transparent and colourless or nearly so. Colourless or pale blue stones are most valued, but most gem diamonds are tinged with yellow. Because of their extreme hardness, diamonds have important industrial applica¬ tions. Most industrial diamonds are gray or brown and are translucent or opaque. In the symbolism of gemstones, the diamond represents steadfast love and is the birthstone for April.

diamond cutting Branch of lapidary art involving the five basic steps in fashioning a diamond: marking, cleaving, sawing, girdling, and face¬ ting. The most popular style is the brilliant cut, a round stone with 58 facets; a round diamond with only 18 facets is known as a single cut. Any other style is known as a fancy cut. See also gemstone.

Diamond Sutra in full Diamond-Cutter Perfection of Wis¬ dom Sutra Wisdom text of Mahayana Buddhism. It was composed c. ad 300 and translated into Chinese c. ad 400. The best known of the wis¬ dom texts contained in the Prajnaparamita, it is written in the form of a dialogue between the Buddha Gautama and a questioning disciple. The work emphasizes the transitory nature of the material world and suggests that spiritual fulfillment can be attained only by transcending ephemeral phenomena and abandoning rationalism.

Dian, Lake Chinese Dlan Chi \'dyen-'che\ or Tien Ch'ih Lake, cen¬ tral Yunnan province, southern China. It is about 25 mi (40 km) long and 8 mi (13 km) wide. The area was settled by sedentary agricultural peoples

as early as the 2nd century bc. It was the centre of the independent state of Dian (Tien), which became tributary to the Han dynasty after 109 bc.

Diana Roman goddess of nature, animals, and the hunt. As a fertility deity, she was invoked for aid in conception and childbirth. She was vir¬ tually indistinguishable from the Greek goddess Artemis. In her cult in Rome she was considered the protector of the lower classes, especially slaves.

Diana, princess of Wales orig. Lady Diana Frances Spencer

(b. July 1, 1961, Sandringham, Norfolk, Eng.—d. Aug. 31, 1997, Paris, France) Consort (1981-96) of Charles, prince of Wales. Daughter of Vis¬ count Althorp (later Earl Spencer), she was a kindergarten teacher at the time of her engagement to Charles, whom she married on July 29, 1981, in a globally televised ceremony. They had two sons. Princes William (1982) and Henry (1984). Her beauty and unprecedented popularity as a member of the royal family attracted intense press attention, and she became one of the most photographed women in the world. The marriage gradually broke down; Charles and Diana separated in 1992 and were divorced in 1996. She remained highly visible and continued her activi¬ ties on behalf of numerous charities. In 1997 she was killed in a car crash in Paris, along with her companion, Emad Mohamed (Dodi) al-Fayed (1955-97), and their driver. Her death brought on a massive public out¬ pouring of grief.

Diane de France \dyan-do- , fra n s\ / duchess de Montmorency and Angouleme (b. 1538, Paris, France—d. Jan. 11, 1619, Paris) Natural daughter (legitimated 1547) of King Henry II of France. In 1559 she was married to Francois de Montmorency (1530-79). She was known for her culture, intelligence, and beauty as well as for the influence she wielded during the reigns of Henry III and Henry IV.

Diane de Poitiers \de-'an-d3-pwa-'tya\, duchess de Valentinois

(b. Sept. 3, 1499—d. April 22,1566, Anet, France) Mistress of King Henry II of France. Diane came to the French court as a lady-in-waiting, where Henry, 20 years her junior, fell violently in love with her. After the death of her husband, Diane became Henry’s mistress from c. 1536. Throughout his reign (1547-59) she held court as queen of France in all but name, while the real queen, Catherine de Medicis, was forced to live in comparative obscu¬ rity. Beautiful and cultivated, Diane was a patron of poets and artists.

Dianetics See Church of Scientology dianthus See pink family

diaphragm \ , di-3-,fram\ Dome-shaped muscular and membranous structure between the thoracic and abdominal cavities. The principal muscle used in respiration, it is also important in coughing, vomiting, excretion, and other expulsive functions. Spasms of the diaphragm pro¬ duce hiccups. The aorta passes behind the diaphragm; the inferior vena cava and esophagus pass through it. Protrusion of part of the stomach above the diaphragm is called a hiatal hernia.

Diarmaid Macmurchada See Dermot Macmurrough

diarrhea \,di-9-'re-9\ Abnormally fast passage of waste material through the large intestine, resulting in frequent defecation with loose feces and sometimes cramps. Causes range widely and can include cholera, dysentery, highly seasoned foods or high alcohol intake, poisons (includ¬ ing food poisoning), drug side effects, and Graves' disease. Mild cases of diarrhea are treated with bismuth subsalicylate (trade name Pepto- Bismol); extreme cases are treated with fluid and electrolyte replacement while the underlying disease passes. Traveler’s diarrhea affects up to half of people who travel to developing countries. Its prevention includes tak¬ ing bismuth subsalicylate tablets, drinking only bottled or canned bever¬ ages, and eating only peeled fruits, canned products, and restaurant food that is well-cooked. Severe cases require antibiotics. In cases of severe malnutrition, diarrhea is potentially lethal, and it is responsible for hun¬ dreds of thousands of deaths annually in underdeveloped countries.

diary or journal Record of events, transactions, or observations kept daily or at frequent intervals; especially a daily record of personal activi¬ ties, reflections, or feelings. Written primarily for the writer’s use alone, the personal diary usually offers a frankness not found in writing done for publication. The diary form, which began to flower in the late Renais¬ sance, is important as a record of social and political history. The most famous diary in English is that of Samuel Pepys. Other notable journals include those of John Evelyn, Jonathan Swift, Fanny Burney, James Boswell, Andre Gide, and Virginia Woolf.

© 2006 Encyclopaedia Britannica, Inc.

542 I Dias ► Dickens

Dias \'de-3sh\, Bartolomeu or Bartholomew Diaz \'de-as\ (b. c. 1450—d. May 29, 1500, at sea, near Cape of Good Hope) Portuguese navigator and explorer. Given command of an expedition to ascertain the southern limit of Africa, he set sail in 1487. He sailed farther south than previous explorers and became the first European to round the Cape of Good Hope (1488). His voyage opened the sea route to Asia via the Atlantic and Indian oceans. He later commanded a ship in an expedition under Pedro Alvares Cabral, in which he participated in the discovery of Brazil; he was lost at sea when they reached the Cape.

Diaspora Ndl-'as-po-ro, de-'as-p9-ro\ Hebrew Galut ("Exile") Greek "Dispersion" The dispersion of Jews among the Gentiles after the Babylonian Exile (586 bc), or the aggregate of Jews outside Palestine or present-day Israel. The term also carries religious, philosophical, politi¬ cal, and eschatological connotations, inasmuch as the Jews perceive a special relationship between the land of Israel and themselves. Interpre¬ tations of this relationship range from the messianic hope of traditional Judaism for the eventual “ingathering of the exiles” to the view of Reform Judaism that the dispersal of the Jews was providentially arranged by God to foster monotheism throughout the world. Historically, Diaspora Jews outnumbered the Jews in Palestine even before the destruction of Jeru¬ salem in ad 70. Thereafter, the chief centres of Judaism shifted from coun¬ try to country (e.g., Babylonia, Persia, Spain, France, Germany, Poland, Russia, and the U.S.), and Jewish communities gradually adopted distinc¬ tive languages, rituals, and cultures, some submerging themselves in non- Jewish environments more completely than others. While some lived in peace, others became victims of violent anti-Semitism. While the vast majority of Orthodox Jews have supported Zionism, some Orthodox Jews go so far as to oppose the modem State of Israel on the grounds that it is a godless and secular state defying God’s will to send his messiah at the time he has preordained.

diastrophism Vdl-'as-tro-.fi-zonA or tectonism Large-scale deforma¬ tion of the Earth’s crust by natural processes, which leads to the forma¬ tion of continents and ocean basins, mountain systems and rift valleys, and other features by mechanisms such as lithospheric plate movement (see plate tectonics), volcanic loading, or folding. The study of diastro¬ phism, or tectonic processes, is the central unifying principle in modem geology and geophysics.

diathermy Vdl-o-.thsr-meX Use of high-frequency electric current for deep heating of tissues in physical therapy. Shortwave, ultrasound, and microwave diathermy heat tissues at different depths for different purposes. Low heat warms tissue to ease muscle pain. Higher degrees of diathermy destroy tissue; this is useful in surgery, particularly on the eye or nerves, to coagulate, limit bleeding, and seal off traumatized tissues.

diatom Vdl-o-.tamV Any member of the algal division or phylum Bacil- lariophyta (about 16,000 species), tiny planktonic (see plankton), uni¬ cellular or colonial algae found float¬ ing in all the waters of the earth. The intricate and delicate markings of the silicified cell wall are useful in test¬ ing the resolving power of micro¬ scope lenses. The beautiful

symmetry and design of diatoms jus¬ tify their title “jewels of the sea.”

Among the most important and pro¬ lific sea organisms, diatoms serve directly or indirectly as food for many animals. Diatomaceous earth, composed of fossil diatoms, is used in filters, insulation, abrasives, paints, and varnishes, and as an insecticide.

diatomaceous V.dl-o-to-'ma-shosV earth or kieselguhr Vke-zol- ,gur\ Light-coloured, porous, and friable sedimentary rock composed of the frustrules (silicate cell walls) of diatoms. It is used in industrial filtra¬ tion applications; as a filler or extender in paper, paint, brick, tile, ceram¬ ics, linoleum, plastic, soap, detergent, and other products; in insulation for boilers, blast furnaces, and other high-temperature devices; as a sound insulator; and as a carrier for herbicides and fungicides. The oldest and best-known commercial use is as a very mild abrasive in metal polishes

ERIC GRAVE-PHOTO RESEARCHERS

and toothpaste. Large deposits occur in California, Nevada, Washington, and Oregon; other sources are Denmark, France, Russia, and Algeria.

Diaz Vde-.asV Porfirio (b. Sept. 15, 1830, Oaxaca, Mex.—d. July 2,

1915, Paris, Fr.) Soldier and presi¬ dent of Mexico (1877-80, 1884— 1911). After training for the priesthood, he pursued a military career instead. When peace was restored to Mexico under Benito JuArez, Diaz resigned his command, but he soon became dissatisfied with the government. After leading two revolts, he was elected president in 1877. He succeeded in bolstering the export economy through foreign investment, while leading in the spirit of a caudillo, suppressing oppo¬ sition, rigging elections, and using patronage to win the cooperation of various groups. The Mexican Revolu¬ tion was launched in 1910 to end his dictatorship and reverse his policies. See also Francisco Madero, La Reforma.

Porfirio Diaz.

LIBRARY OF CONGRESS, WASHINGTON, D.C.

Dibdin, Charles (baptized March 4, 1745, Southampton, Hampshire, Eng.—d. July 25, 1814, London) British composer, novelist, and actor. A cathedral chorister, Dibdin began working for a music publisher at age 15 and began his stage career in 1762. His first operetta was The Shepherd’s Artifice (1764). By 1778, when he became exclusive composer for Cov¬ ent Garden, he had produced eight operas, including The Padlock (1768), The Waterman (1774), and The Quaker (1775). He later produced his bal¬ lad opera Liberty Hall. He was author, singer, and accompanist for his celebrated one-man “table entertainments”; most of his popular sea songs were written for these. In all, he wrote about 100 stage works and 1,400 songs. He was one of the most popular British composers of the 18th cen¬ tury.

Dibon \'dl-,ban\ modern DhTban \the-'ban\ Ancient city of Palestine. The capital of Moab, it was located north of the Arnon River in what is now west-central Jordan. Excavations have uncovered the remains of city walls and numerous buildings; pottery found at the site dates from c. 3200 bc to the 7th century ad. One of the most important finds was the Moabite Stone, written in the Moabite alphabet, an important representation of the Phoenician script. Dating from the 9th century bc, it commemorates a victory over the Israelites. See also Moabites.

dice Set of small cubes (each called a die) marked on each face with from one to six spots and used in gambling and in various social games by being shaken and thrown down to come to rest at random on a flat surface. The combined number of the spots on the topmost surface of the tossed dice decides, according to the rules of the game being played, whether the thrower (or “shooter”) wins, loses, or continues to throw. In numerous board games the thrown dice determine the player’s moves. Dice, which may be traced back to prehistory, were in many cultures magical devices used for the casting of lots to divine the future. In the modern era they became associated with the playing of games of chance, including craps.

dickcissel \dik-'si-sol, 'dik-.si-soL American passerine ( Spiza americana, family Fringillidae) bird that eats seeds and breeds in weedy fields of the central U.S. Most dickcissels winter in northern South America, but some stray to the Atlantic coast.

The male, for whose song the species is named, is a streaky brown bird 6.5 in. (16 cm) long, with a black bib on its yellow breast, resembling a min¬ iature MEADOWLARK.

Dickens, Charles (John Huf- fam) (b. Feb. 7, 1812, Portsmouth,

Hampshire, Eng.—d. June 9, 1870,

Gad’s Hill, near Chatham, Kent)

British novelist, generally considered the greatest of the Victorian period.

Dickcissel [Spiza americana)

THASE DANIEL

© 2006 Encyclopaedia Britannica, Inc.

Dickey ► Didot family I 543

The defining moment of Dickens’s life occurred when he was 12 years old. With his father in debtors’ prison, he was withdrawn from school and forced to work in a factory. This deeply affected the sensitive boy. Though he returned to school at 13, his formal education ended at 15. As a young man, he worked as a reporter. His fiction career began with short pieces reprinted as Sketches by “Boz” (1836). He exhibited a great ability to spin a story in an entertaining manner and this quality, combined with the seri¬ alization of his comic novel The Pickwick Papers (1837), made him the most popular English author of his time. The serialization of such works as Oliver Twist (1838) and The Old Curiosity Shop (1841) followed. After a trip to America, he wrote A Christmas Carol (1843) in a few weeks. With Dombey and Son (1848), his novels began to express a heightened uneasiness about the evils of Victorian industrial society, which intensi¬ fied in the semiautobiographical David Copperfield (1850), as well as in Bleak House (1853), Little Dorrit (1857), Great Expectations (1861), and others. A Tale of Two Cities (1859) appeared in the period when he achieved great popularity for his public readings. Dickens’s works are characterized by an encyclopaedic knowledge of London, pathos, a vein of the macabre, a pervasive spirit of benevolence and geniality, inex¬ haustible powers of character creation, an acute ear for characteristic speech, and a highly individual and inventive prose style.

Dickey, James (Lafayette) (b. Feb. 2, 1923, Atlanta, Ga., U.S.—d. Jan. 19, 1997, Columbia, S.C.) U.S. poet, novelist, and critic. Dickey served as a pilot in World War II. His poetry—published in such volumes as Into the Stone (1960), Drowning with Others (1962), Helmets (1964), Buckdancer’s Choice (1965), and The Zodiac (1976)—combines themes of nature mysticism, religion, and history. He became widely known with his powerful novel Deliverance (1970; film, 1972).

Dickinson, Emily (Elizabeth) (b. Dec. 10, 1830, Amherst, Mass., U.S.—d. May 15, 1886, Amherst) U.S. poet. Granddaughter of the cofounder of Amherst College and daughter of a respected lawyer and one-term congressman, Dickinson was educated at Amherst (Mass.) Acad¬ emy and Mount Holyoke Female Seminary. She subsequently spent vir¬ tually all her life, increasingly reclusive, in her family home in Amherst. She began writing in the 1850s; by 1860 she was boldly experimenting with language and prosody, striving for vivid, exact words and epigram¬ matic concision while adhering to the basic quatrains and metres of the Protestant hymn. The subjects of her deceptively simple lyrics, whose depth and intensity contrast with the apparent quiet of her life, include love, death, and nature. Her numerous letters are sometimes equal in art¬ istry to her poems. By 1870 she was dressing only in white and declin¬ ing to see most visitors. Of her 1,775 poems, only seven were published during her lifetime. After posthumous publications (some rather inaccu¬ rate), her reputation and readership grew. Her complete works were pub¬ lished in 1955, and she has since become universally regarded as one of the greatest American poets.

Dickinson, John (b. Nov. 8, 1732, Talbot county, Md.—d. Feb. 14, 1808, Wilmington, Del., U.S.) American statesman. He represented Penn¬ sylvania at the 1765 Stamp Act Congress and drafted the Congress’s dec¬ laration of rights and grievances. He won fame in 1767-68 as the author of the Letters from a Farmer in Pennsylvania, to the Inhabitants of the British Colonies, which influenced opinion against the Townshend Acts. A delegate to the Continental Congress, he helped draft the Articles of Confederation. Hoping for conciliation with the British, he voted against the Declaration of Independence. As a Delaware delegate to the Constitu¬ tional Convention, he signed the U.S. Constitution and urged its adoption in a series of letters signed “Fabius.” He is sometimes called the “pen¬ man of the Revolution.”

dicot See cotyledon, flowering plant

dictator In the Roman republic, a temporary magistrate with extraordi¬ nary powers. Nominated in times of crisis by a consul, recommended by the Senate, and confirmed by the Comitia Curiata, the dictator’s term was six months or the duration of the crisis, and he had authority over all other magistrates. By 300 bc his powers were limited; no dictators were cho¬ sen after 202. The dictatorships of Sulla and Julius Caesar were a new form with almost unlimited powers. Caesar became dictator for life just before his assassination; afterward the office was abolished.

dictatorship Form of government in which one person or an oligarchy possesses absolute power without effective constitutional checks. With constitutional democracy, it is one of the two chief forms of government in use today. Modern dictators usually use force or fraud to gain power

and then keep it through intimidation, terror, suppression of civil liber¬ ties, and control of the mass media. In 20th-century Latin America, nation¬ alist leaders often achieved power through the military and attempted either to maintain the privileged elite or to institute far-reaching social reform, depending on their class sympathies. In Europe’s communist and fascist dictatorships, a charismatic leader of a mass party used an official ideology to maintain his regime, and terror and propaganda to suppress opposition. In postcolonial Africa and Asia, dictators have often retained power by establishing one-party rule after a military takeover.

dictionary Reference work that lists words, usually in alphabetical order, and gives their meanings and often other information such as pro¬ nunciations, etymologies, and variant spellings. The earliest dictionaries, such as those created by Greeks of the 1 st century ad, emphasized changes that had occurred in the meanings of words over time. The close juxta¬ position of languages in Europe led to the appearance, from the early Middle Ages on, of many bilingual and multilingual dictionaries. The movement to produce an English dictionary was partly prompted by a desire for wider literacy, so that common people could read Scripture, and partly by a frustration that no regularity in spelling existed in the lan¬ guage. The first purely English dictionary was Robert Cawdrey’s A Table Alphabetical (1604), treating some 3,000 words. In 1746-47 Samuel Johnson undertook the most ambitious English dictionary to that time, a list of 43,500 words. Noah Webster’s dictionary of Americanisms in the early 19th century sprang from a recognition of the changes and varia¬ tions within language. The immense Oxford English Dictionary was begun in the late 19th century. Today there are various levels of dictionaries, general-purpose dictionaries being most common. Modern lexicographers (dictionary makers) describe current and past language but rarely pre¬ scribe its use.

Diderot \ded-'roV Denis (b. Oct. 5, 1713, Langres, France—d. July 31, 1784, Paris) French man of let¬ ters and philosopher. Educated by Jesuits, Diderot later received degrees from the University of Paris.

From 1745 to 1772 he served as chief editor of the 35-volume Ency- clopedie, a principal work of the Enlightenment. He composed such influential works as Letter on the Deaf and Dumb (1751), which stud¬ ies the function of language, and Thoughts on the Interpretation of Nature (1754), acclaimed as the method of philosophical inquiry of the 18th century. The first great art critic, he was especially admired posthumously for his Essay on Painting (written 1765). His novels include The Nun (written 1760) and Rameau’s Nephew (finished 1774); he also wrote plays and theoretical works on drama. See also Jean Le Rond d’ Alembert.

Didion, Joan (b. Dec. 5, 1934, Sacramento, Calif., U.S.) U.S. novelist and essayist. Her writing explores disorder and personal and social unrest. Her first novel was published in 1963; later novels include Play It as It Lays (1970), A Book of Common Prayer (1977), Democracy (1984), and The Last Thing He Wanted (1996). Her essay collections Slouching Towards Bethlehem (1968) and The White Album (1979) are perceptive, clear-eyed analyses of American culture. With her husband, John Gregory Dunne, she has written a number of screenplays, including A Star Is Born

(1976).

Dido \'di-do \ In Greek legend, the founder of Carthage. She fled to North Africa after the murder of her husband and bought land from a local chieftain, Iarbas. She killed herself rather than marry him. Virgil altered the story in his Aeneid, in which Dido welcomes Aeneas to Carthage dur¬ ing his travels, becomes his lover, and kills herself when he abandons her.

Didot family \de-'do\ Family of French printers, publishers, and type¬ founders. The family had a profound influence on the history of typog¬ raphy. Francois Didot (1689-1759) went into business as a printer and bookseller in Paris in 1713. Three successive generations kept the firm

Denis Diderot, oil painting by Louis- Michel van Loo, 1767; in the Louvre, Paris.

GIRAUDON/ART RESOURCE, NEW YORK

© 2006 Encyclopaedia Britannica, Inc.

544 I Didrikson ► dieting

flourishing into the 19th century. Under Francois’s elder son, Fran^ois- Ambroise (1730-1804), the Didot point system of 72 points to the French inch became the standard unit of type measurement, as it remains today. Francois-Ambroise changed the standard of type design by increasing the contrast between thick and thin letters. His sons Pierre (1761-1853) and Firmin (1764-1836) took charge of the printing and typefounding, respec¬ tively. Pierre published acclaimed editions of French and Latin classics, and Firmin designed the Didot typeface. Francois’s younger son, Pierre- Francois (1731-1793), and the latter’s two sons were also active in the business, as were Firmin’s three sons.

Didrikson, Babe See Babe Didrikson Zaharias

Didyma \'di-do-mo \ Ancient sanctuary, south of Miletus in modern Tur¬ key. Its temple, the seat of an oracle of Apollo, was plundered by the Per¬ sians c. 494 bc and resanctified after Alexander the Great conquered Miletus in 334 bc. About 300 bc the Milesians began to build a new temple, but it was never completed; the well-preserved remains were excavated in the early 20th century.

die Tool or device for imparting a desired shape, form, or finish to a material. Examples include a perforated block through which metal or plastic is drawn or extruded, the hardened steel forms for producing the patterns on coins and medals by pressure, and the hollow molds into which metal or plastic is forced. Modern tools and dies can be traced to the work of Honore Blanc at the Saint-Etienne armoury in France beginning in 1780. Blanc’s techniques were adopted and enlarged in the LJ.S. by Eli Whitney and others, who used templates (tool-guiding patterns) and fixtures—the antecedents of today’s tools and dies—to mass-produce fire¬ arms for the U.S. Army (see armoury practice). Today the demand for dies used in metal forming, die casting, and plastic molding is filled by tool- and die-making shops.

Die Brucke See Die Briicke

die casting Forming metal objects by injecting molten metal under pressure into dies or molds. An early and important use of the technique was in the Linotype machine (1884), but the mass-production automobile assembly line gave die casting its real impetus. Great precision is pos¬ sible, and products range from tiny parts for sewing machines and auto¬ mobiles to aluminum engine-block castings.

die making See tool and die making

Diebenkorn Vde-bon-.kornX, Richard (b. April 22, 1922, Portland, Ore., U.S.—d. March 30, 1993, Berkeley, Calif.) U.S. painter. After study¬ ing at Stanford University, he taught at California Institute of the Arts (1947-50), and there developed an abstract style under the influence of such painters as Clyfford Still and Mark Rothko. By the mid 1950s he had achieved some commercial success but turned to an expressionistic figu¬ rative style. He produced accomplished figure drawings, still lifes, land¬ scapes, and interiors in the Modernist tradition. Throughout his career he alternated between figuration and abstraction. His best-known works are the Ocean Park series, begun in the 1960s, comprising over 140 large abstract paintings that retain allusions to landscape.

Diefenbaker Vde-fon-.ba-korV John G(eorge) (b. Sept. 18, 1895, Grey county, Ont., Can.—d. Aug. 16, 1979, Ottawa) Prime minister of Canada (1957-63). After serving in World War I, he practiced law in Saskatchewan. He was elected to the Canadian House of Commons in 1940. He became leader of the Progressive Conservative Party in 1956 and served as prime minister from 1957 to 1963, when his party lost its majority in the House of Commons. He resigned as party leader in 1967. He was chancellor of the University of Saskatchewan from 1969 until his death.

dielectric \,dl-i-'lek-trik\ Insulating material or a very poor conductor of electric current. Dielectrics have no loosely bound electrons, and so no current flows through them. When they are placed in an electric field, the positive and negative charges within the dielectric are displaced minutely in opposite directions, which reduces the electric field within the dielec¬ tric. Examples of dielectrics include glass, plastics, and ceramics.

Diemen Vde-monV, Anthony van (b. 1593, Culemborg, Neth.—d. April 19, 1645, Batavia, Dutch East Indies) Dutch colonial administrator who consolidated the Dutch empire in the Far East. He joined the Dutch East India Company and served in Batavia from 1618. As governor-general of the Dutch East Indian settlements (1636-45), he enabled the Dutch to gain a monopoly of the spice trade in the Moluccas, conquer cinnamon-

producing areas in Ceylon (Sri Lanka), seize the key Portuguese strong¬ hold of Malacca, and capture all of Formosa (Taiwan). By 1645 he had established the United Provinces of The Netherlands as the paramount commercial and political power in the East Indies. Van Diemen also ini¬ tiated the exploring expeditions of Abel Janszoon Tasman and Frans Viss- cher (1642, 1644).

Dien Bien Phu Ydyen-'byen-'fiA, Battle of (1953-54) Decisive engagement in the first of the Indochina wars (1946-54) that marked the end of French involvement in Southeast Asia. The French fought the Viet Minh (Lien Viet) for control of a small mountain outpost near Laos. The French occupied the outpost, but the Vietnamese cut all the roads into it, leaving the French to rely on air supplies. Gen. Vo Nguyen Giap then attacked the base with heavy artillery and a force of 40,000 men; the base fell to him despite heavy U.S. aid to the French.

Dieppe Vdyep, de-'ep\ Town (pop., 1999: 34,598) and seaport, northern France, on the English Channel. French kings, realizing its strategic impor¬ tance, granted it numerous privileges. In 1668 almost 10,000 of its people died during a plague, and in 1694 the town was almost completely destroyed by English and Dutch fleets. In World War II it was the site of an unsuccessful Allied commando landing (1942). Its port is one of the safest on the Channel, but its shallowness hinders modern shipping.

Dies \'dlz\, Martin, Jr. (b. Nov. 5, 1901, Colorado, Texas, U.S.—d. Nov. 14, 1972, Lufkin, Texas) U.S. politician. He received a law degree from National University in Washington, D.C. in 1920. After practicing law in Texas, he won a seat in the U.S. House of Representatives (1931— 45, 1953-59). Though originally a supporter of the New Deal, by 1937 he had turned against it. In 1938 he was named chairman of the newly cre¬ ated House Un-American Activities Committee; popularly known as the Dies Committee, it pursued alleged communist subversives in New Deal agen¬ cies and labour unions. Wheareas conservatives applauded the exposure of supposedly disloyal government and union officials, liberals accused Dies of smearing reputations with unproved charges.

Diesel, Rudolf Christian Karl (b. March 18, 1858, Paris, France—d. Sept. 29, 1913, at sea in the English Channel) German thermal engineer. In the 1890s he invented the internal-combustion engine that bears his name, producing a series of increasingly successful models of the diesel engine that culminated in his demonstration in 1897 of a 25-horsepower, four-stroke, single vertical cylinder compression engine.

diesel engine Internal-combustion engine in which air is compressed to a temperature sufficiently high to ignite fuel injected into the cylinder, where combustion and expansion activate a piston (see piston and cylin¬ der). It converts the chemical energy stored in the fuel into mechanical energy, which can be used to power large trucks, locomotives, ships, small electric-power generators, and some automobiles. The diesel engine dif¬ fers from other internal-combustion engines (such as gasoline engines) in that it has no ignition system and so is often called a compression-ignition engine. Diesel fuel is low-grade and comparatively unrefined. Compared to other internal-combustion engines, diesel engines are more reliable, last longer, and cost less to operate, but they also produce more air pollution, noise, and vibration.

Diet Japanese national legislature. Under the Meiji Constitution, the Diet had two houses, a House of Peers and a House of Representatives, with equal powers. The Diet’s role was largely negative: it could block legis¬ lation and veto budgets. It was reconstituted under the U.S.-sponsored constitution of 1947. The (upper) House of Councillors seats 247 mem¬ bers, and the (lower) House of Representatives has 480 members. The prime minister, who leads the majority party in the lower house, must be a member. The House of Representatives can override the House of Coun¬ cillors on most issues.

Diet of Worms See Diet of Worms dietary fibre See dietary fibre

dieting Regulating food intake to improve physical condition, especially to lose weight. Examples include diets low in fat for weight loss, low in saturated fat and cholesterol to prevent or help treat coronary heart dis¬ ease, or high in carbohydrates and protein to build muscle. Weight-loss diets are based on reducing calorie intake in different proportions of fat, car¬ bohydrate, or protein; most result in some weight loss, but often the weight is gained back within a few years. Diets must include adequate

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