Encyclopædia Britannica Australia -

Encyclopedias since 1768

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Direct Action ... display behaviour

Direct Action: French clandestine terrorist group that emerged in 1979 and is believed to have been an amalgam of earlier extremist groups. Sometimes compared with older terrorist groups such as the Italian Red Brigades and the German Red Army Faction, Direct Action ...
direct current: flow of electric charge that does not change direction. Direct current is produced by batteries, fuel cells, rectifiers, and generators with commutators. Direct current was supplanted by alternating current (AC) for common commercial power in the late 1880s because it ...
direct dye: any of a class of coloured, water-soluble compounds that have an affinity for fibre and are taken up directly, such as the benzidine derivatives. Direct dyes are usually cheap and easily applied, and they can yield bright colours. Washfastness is ...
directing: the craft of controlling the evolution of a performance out of material composed or assembled by an author. The performance may be live, as in a theatre and in some broadcasts, or it may be recorded, as in motion pictures ...
direction field: way of graphically representing the solutions of a first-order differential equation without actually solving the equation. The equation y' = f (x,y) gives a direction, y', associated with each point (x,y) in the plane that must be satisfied by any ...
direction finder: radio receiver and antenna system for determining the direction of the source of a radio signal. A direction finder (DF) can be used by an aircraft or ship as a navigational aid. This is accomplished by measuring the direction (bearing) ...
Directoire style: style of dress, furniture, and ornament popular in France during the period of the Directory (1795-99). Dress for men, mixing ancient and contemporary elements, featured trousers and high boots, vests, long, open coats, and top hats. Women dressed in chemises ...
Directory: the French Revolutionary government set up by the Constitution of the Year III, which lasted four years, from November 1795 to November 1799.
Diriamba: city, southwestern Nicaragua. It lies in the Diriamba Highlands at an elevation of 1,891 feet (576 m). Diriamba is a major commercial and manufacturing centre; its hinterland is known primarily for its coffee, but lumbering is also significant. Limestone quarries ...
Dirichlet problem: in mathematics, the problem of formulating and solving certain partial differential equations that arise in studies of the flow of heat, electricity, and fluids. Initially, the problem was that of determining the equilibrium temperature distribution on a disk from measurements ...
Dirichlet's theorem: statement that there are infinitely many prime numbers contained in the collection of all numbers of the form na + b, in which the constants a and b are integers that have no common divisors except the number 1 (in ...
Dirichlet, Peter Gustav Lejeune: German mathematician who made valuable contributions to number theory, analysis, and mechanics. He taught at the universities of Breslau (1827) and Berlin (1828-55) and in 1855 succeeded Carl Friedrich Gauss at the University of Gottingen.
Dirk Hartog Island: Australian island in the Indian Ocean, just north of Edel Land Peninsula, Western Australia. Naturaliste Channel passes north to enter Denham Sound (which washes the eastern shore), and Shark Bay lies to the northeast. The island was named after a ...
Dirks, Rudolph: U.S. cartoonist who created the comic strip "Katzenjammer Kids."
Dirksen, Everett McKinley: U.S. politician, leader of the Senate Republicans during the Kennedy and Johnson administrations.
Dis Pater: (Latin: Rich Father), in Roman religion, god of the infernal regions, the equivalent of the Greek Hades (q.v.), or Pluto (Rich One). Also known to the Romans as Orcus, he was believed to be the brother of Jupiter and was ...
Disa: genus of orchids, family Orchidaceae, containing as many as 200 species of plants. They grow in marshes and grasslands in southeastern Africa, Madagascar, and on nearby islands.
disaccharide: any substance that is composed of two molecules of simple sugars (monosaccharides) linked to each other. Sucrose, which is formed following photosynthesis in green plants, consists of one molecule of glucose and one of fructose; lactose (milk sugar), found in ...
disarmament: in international relations, any of four distinct conceptions: (1) the penal destruction or reduction of the armament of a country defeated in war (the provision under the Versailles Treaty [1919] for the disarmament of Germany and its allies is an ...
disbarment: the process whereby an attorney is deprived of his license or privileges for failure to carry out his practice in accordance with established standards. Temporary suspension may be employed if some lesser punishment is warranted.
disc jockey: person who conducts a program of recorded music on radio, on television, or at discotheques or other dance halls. Disc jockey programs became the economic base of many radio stations in the United States after World War II. The format ...
discharge printing: method of applying a design to dyed fabric by printing a colour-destroying agent, such as chlorine or hydrosulfite, to bleach out a white or light pattern on the darker coloured ground. In colour-discharge printing, a dye impervious to the bleaching ...
Disciples of Christ: group of Protestant churches that originated in the religious revival movements of the American frontier in the early 19th century. There are three major bodies of the Disciples of Christ, all of which stem from a common source.
disco: beat-driven style of popular music that was the preeminent form of dance music in the 1970s. Its name was derived from discotheque, the name for the type of dance-oriented nightclub that first appeared in the 1960s.
Discoglossidae: family of primitive toads (order Anura) whose tongues are disk-shaped. The family contains four genera, which are confined to the Old World. Representatives occur in Europe, northern Africa, China, Korea, and the Philippines.
discount rate: interest rate charged by a central bank for loans of reserve funds to commercial banks and other financial intermediaries. This charge originally was an actual discount (an interest charge held out from the amount loaned), but the rate is now ...
discount store: in merchandising, a retail store that sells products at prices lower than those asked by traditional retail outlets. Some discount stores are similar to department stores in that they offer a wide assortment of goods; indeed, some are called discount ...
Discoverer: any of a series of unmanned experimental satellites launched by the United States Air Force. Although the Discoverer satellites had several apparent applications-such as testing orbital maneuvering and reentry techniques-they often are regarded as a forerunner of the military reconnaissance ...
discovery: in law, pretrial procedures providing for the exchange of information between the parties involved in the proceedings. Discovery may be made through interrogatories, which consist of written questions sent from one side to the other in an attempt to secure ...
Discovery Bay: wide curved bay indenting the south coast of Australia. An inlet of the Indian Ocean, it is 50 miles (80 km) across and is bounded on the east by Cape Bridgewater (Victoria) and on the west by Cape Northumberland (South ...
discriminant: in mathematics, a parameter of an object or system calculated as an aid to its classification or solution. In the case of a quadratic equation ax² + bx + c = 0, the discriminant is b² − 4ac; for a cubic equation x³ + ax² + bx + c = 0, the discriminant is a²b² + 18abc − 4b³ − 4a³c − 27c². The ...
discrimination: in psychology, the ability to perceive and respond to differences among stimuli. It is considered a more advanced form of learning than generalization (q.v.), the ability to perceive similarities, although animals can be trained to discriminate as well as to ...
discus fish: two species of the genus Symphysodon of fishes in the family Cichlidae (order Perciformes), characterized by a compressed, disk-shaped body. The two species (S. discus and S. aequifasciata) occur naturally in tributaries of the Amazon River in South America. Discus ...
discus throw: sport in athletics (track and field) in which a disk-shaped object, known as a discus, is thrown for distance. In modern competition the discus must be thrown from a circle 2.5 metres (8.2 feet) in diameter and fall within a ...
disease: a harmful deviation from the normal structural or functional state of an organism. A diseased organism commonly exhibits signs or symptoms indicative of its abnormal state. Thus, the normal condition of an organism must be understood in order to recognize ...
disease: an impairment of the normal state of an organism that interrupts or modifies its vital functions.
disinfectant: any substance, such as creosote or alcohol, applied to inanimate objects to kill microorganisms. Disinfectants and antiseptics are alike in that both are germicidal, but antiseptics are applied primarily to living tissue. The ideal disinfectant would rapidly destroy bacteria, fungi, ...
disjunction: in logic, relation or connection of terms in a proposition to express the concept "or"; it is a statement of alternatives (sometimes called "alternation"). For clarity, exclusive disjunction (either x or y but not both), symbolized x ∨· y, x ...
disk-winged bat: any of three species of bats inhabiting Central America and northern South America that are distinguished by round disks at the base of the thumb and on the sole of the foot.
dislocation: in physiology and medicine, displacement of the bones forming a joint, with consequent disruption of tissues.
Disney Company: American corporation that was the best-known purveyor of family entertainment in the 20th century.
Disney, Walt: American motion-picture and television producer and showman, famous as a pioneer of animated cartoon films and as the creator of such cartoon characters as Mickey Mouse and Donald Duck. He also planned and built Disneyland, a huge amusement park that ...
disorderly conduct: in law, intentional disturbing of the public peace and order by language or other conduct. It is a general term including various offenses that are usually punishable by minor penalties.
dispensation: in Christian ecclesiastical law, the action of a competent authority in granting relief from the strict application of a law. It may be anticipatory or retrospective.
dispersion: in wave motion, any phenomenon associated with the propagation of individual waves at speeds that depend on their wavelengths. Ocean waves, for example, move at speeds proportional to the square root of their wavelengths; these speeds vary from a few ...
dispersion: in biology, the dissemination, or scattering, of organisms over periods within a given area or over the Earth.
displacement: in mechanics, distance moved by a particle or body in a specific direction. In the , A is the initial position of a point, B is the final position, and the straight line directed from A to B is the ...
displacement activity: the performance by an animal of an act inappropriate for the stimulus or stimuli that evoked it. Displacement behaviour usually occurs when an animal is torn between two conflicting drives, such as fear and aggression. Displacement activities often consist of ...
displacement current: in electromagnetism, a phenomenon analogous to an ordinary electric current, posited to explain magnetic fields that are produced by changing electric fields. Ordinary electric currents, called conduction currents, whether steady or varying, produce an accompanying magnetic field in the vicinity ...
displacement law: in physics, any of the statements (originally formulated in 1913) that radioactive decay produces daughter atoms whose position in the periodic table of the chemical elements is shifted from that of their parents: two lower for alpha decay and one ...
display behaviour: ritualized behaviour by which an animal provides specific information to others, usually members of its own species. Virtually all higher animals use displays to some extent. The best-known displays are visual ones-and some biologists restrict the term display to visual ...