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