Encyclopædia Britannica Australia -

Encyclopedias since 1768

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racism ... radiolarian

racism: any action, practice, or belief that reflects the racial worldview-the ideology that humans are divided into separate and exclusive biological entities called "races," that there is a causal link between inherited physical traits and traits of personality, intellect, morality, and ...
rack and pinion: mechanical device consisting of a bar of rectangular cross section (the rack), having teeth on one side that mesh with teeth on a small gear (the pinion). The pinion may have straight teeth, as in the figure, or helical (twisted) ...
rackets: game played with a ball and a strung racket in an enclosed court, all four walls of which are used in play. Rackets is played with a hard ball in a relatively large court, usually about 18 m (60 ft) ...
rackett: (from German Rank, "bend"), in music, double-reed wind instrument of the 16th and 17th centuries. It consisted of a short wooden or ivory cylinder bored with six or seven extremely narrow channels connected in a series and emerging at the ...
Rackham, Arthur: British artist best known for his illustrations for classic fiction and children's literature.
rada': (Arabic: "to suckle"), in Islam, a legal relationship established between children when they are nursed by the same woman, the result being that they are forbidden to intermarry. Such a prohibition was prevalent in Arabian society even before Islam. Arabs ...
radar: electromagnetic sensor used for detecting, locating, tracking, and recognizing objects of various kinds at considerable distances. It operates by transmitting electromagnetic energy toward objects, commonly referred to as targets, and observing the echoes returned from them. The targets may be ...
Radbruch, Gustav: German jurist and legal philosopher, one of the foremost exponents of legal relativism and legal positivism. Radbruch served on the faculties of the universities at Konigsberg, Kiel, and Heidelberg. He also served the Weimar government as a minister of justice ...
Radcliffe, Ann: nee Ward the most representative of English Gothic novelists. She stands apart in her ability to infuse scenes of terror and suspense with an aura of romantic sensibility.
Radcliffe-Brown, A R: English social anthropologist of the 20th century who developed a systematic framework of concepts and generalizations relating to the social structures of relatively simple societies.
Raddall, Thomas Head: English-Canadian novelist, who accurately depicted the history, manners, and idiom of Nova Scotians.
Radegunda, Saint: queen of the Merovingian king Chlotar I, who left her husband to become a nun and later founded a monastery at Poitiers. She was one of the first of the Merovingian saints.
Radek, Karl: original name Karl Sobelsohn Communist propagandist and early leader of the Communist International (Comintern), who fell victim to Joseph Stalin's Great Purge of the 1930s.
raden: Japanese decorative technique used for lacquerware and woodenware, in which linings of mother-of-pearl or of abalone shells are cut into designs and either glued onto or inserted into the surface of the lacquer or wood. There are several varieties of ...
Radescu, Nicolae: Romanian army officer and prime minister of Romania (December 1944-March 1945).
Radetzky, Joseph, Graf: Austrian field marshal and military reformer, whose long record of victorious campaigns made him a national hero.
Radewyns, Florentius: Dutch Roman Catholic theologian, successor to Gerhard Groote as leader of the Brethren of the Common Life, a community of laymen dedicated to the care and education of the poor, and founder of the monastic Congregation of Windesheim.
Radha: in Hindu mythology, the mistress of the god Krishna during that period of his life when he lived among the cowherds of Vrndavana. Radha was the wife of another gopa (cowherd) but was the most beloved of Krishna's consorts and ...
Radha Soami Satsang: esoteric religious sect of India that has followers among both Hindus and Sikhs. The sect was founded in 1861 by Siva Dayal Saheb (also called Sivdayal), a Hindu banker of Agra, who believed that human beings could perfect their highest ...
Radhakrishnan, Sarvepalli: scholar and statesman who was president of India from 1962 to 1967. He served as professor of philosophy at Mysore (1918-21) and Calcutta (1921-31; 1937-41) universities and as vice chancellor of Andhra University (1931-36). He was professor of Eastern religions ...
radial keratotomy: surgical procedure to correct myopia (nearsightedness) by reducing the radius of curvature of the cornea and astigmatism (asymmetrical curvature of the cornea). A series of 4 to 8 equally spaced deep cuts are made in the peripheral cornea, leaving the ...
radiation: flow of atomic and subatomic particles and of waves, such as those that characterize heat rays, light rays, and X rays. All matter is constantly bombarded with radiation of both types from cosmic and terrestrial sources. This article delineates the ...
radiation: either the process by which energy is emitted from a source and propagated through the surrounding medium or the energy involved in this process. Familiar examples of radiant energy include light (a form of electromagnetic radiation) and sound (a form ...
radiation injury: tissue damage or changes caused by exposure to ionizing radiation-namely, gamma rays, X rays, and such high-energy particles as neutrons, electrons, and positrons. Sources of ionizing radiation may be natural (e.g., radioactive substances such as the element radium or the ...
radiation measurement: technique for detecting the intensity and characteristics of ionizing radiation, such as alpha, beta, and gamma rays or neutrons, for the purpose of measurement.
radiation pressure: the pressure on a surface resulting from electromagnetic radiation that impinges on it, which results from the momentum carried by that radiation; radiation pressure is doubled if the radiation is reflected rather than absorbed.
radiation therapy: use of radiation sources in the treatment or relief of diseases. Radiation therapy almost always makes use of ionizing radiation, deep tissue-penetrating rays, which can physically and chemically react with diseased cells to destroy them. The other forms of radiation, ...
radiation-damage dating: method of age determination that makes use of the damage to crystals and the radiation from radioactive substances caused by storage of energy in electron traps. In the mineral zircon, for example, radiation damage results in a change in colour, ...
Radic, Stjepan: peasant leader and advocate of autonomy for Croatia (within a federalized Yugoslavia).
radical: in politics, one who desires extreme change of part or all of the social order. The word was first used in a political sense in England, and its introduction is generally ascribed to Charles James Fox, who in 1797 declared ...
radical: in chemistry, molecule that contains at least one unpaired electron. Most molecules contain even numbers of electrons, and the covalent chemical bonds holding the atoms together within a molecule normally consist of pairs of electrons jointly shared by the atoms ...
Radical Civic Union: major centre-left political party in Argentina. For much of the 20th century, the Radical Civic Union (UCR) was the primary opposition party to the Peronists, who are represented by the Justicialist Party. The UCR draws significant support from Argentina's urban ...
Radical Democratic Party: centrist political party of Switzerland. With the Christian Democratic People's Party, the Social Democratic Party, and the Swiss People's Party, the Radical Democratic Party has governed Switzerland as part of a grand coalition since 1959.
radical empiricism: a theory of knowledge and a metaphysics (theory of Being) advanced by William James, an American pragmatist philosopher and psychologist, based on the pragmatic theory of truth and the principle of pure experience, which contends that the relations between things ...
Radical Republican: during and after the American Civil War, a member of the Republican Party committed to emancipation of the slaves and later to the equal treatment and enfranchisement of the freed blacks.
Radical-Socialist Party: the oldest of the French political parties, officially founded in 1901 but tracing back to "radical" groups of the 19th century. Traditionally a centrist party without rigid ideology or structure, it was most prominent during the Third Republic (to 1940) ...
Radiguet, Raymond: precocious French novelist and poet who wrote at 17 a masterpiece of astonishing insight and stylistic excellence, Le Diable au corps (1923; The Devil in the Flesh), which remains a unique expression of the poetry and perversity of an adolescent ...
Radin, Paul: U.S. anthropologist who was influential in advancing a historical model of primitive society based on a synthesis of economic and social structure, religion, philosophy, and psychology. He pioneered in such important fields of anthropology as culture-personality studies and the use ...
radio: transmission and detection of communication signals consisting of electromagnetic waves that travel through the air in a straight line or by reflection from the ionosphere or from a communications satellite.
radio and radar astronomy: study of celestial bodies by examination of the radio-frequency energy they emit or reflect.
radio direction finder: radio receiver and directional antenna system used to determine the direction of the source of a signal. It most often refers to a device used to check the position of a ship or aircraft, although it may also direct a ...
radio interferometer: apparatus that is used to study heavenly bodies by receiving and analyzing electromagnetic radiation that these bodies emit or reflect in the radio wavelengths. A radio interferometer is a radio telescope (q.v.) consisting of two or more separate antennas receiving ...
radio range: in aerial navigation, a system of radio transmitting stations, each of which transmits a signal that not only carries identification but also is of intrinsic value to a navigator in fixing his position. The older "A-N" type, dating from 1927, ...
radio source: in astronomy, any of various objects in the universe that emit relatively large amounts of radio waves. Nearly all types of astronomical objects give off some radio radiation, but the strongest sources of such emissions include pulsars, certain nebulas, quasars, ...
radio telescope: astronomical instrument consisting of a radio receiver and an antenna system that is used to detect radio-frequency radiation emitted by extraterrestrial sources. Because radio wavelengths are much longer than those of visible light, radio telescopes must be very large in ...
radio-frequency heating: process of heating materials through the application of radio waves of high frequency-i.e., above 70,000 hertz (cycles per second). Two methods of radio-frequency heating have been developed. One of these, induction heating, has proved highly effective for heating metals and ...
radioactive fallout: the deposition of radioactive materials on the Earth from the atmosphere. See fallout.
radioactive isotope: any of several species of the same chemical element with different masses whose nuclei are unstable and dissipate excess energy by spontaneously emitting radiation in the form of alpha, beta, and gamma rays.
radioactive series: any of four independent sets of unstable heavy atomic nuclei that decay through a sequence of alpha and beta decays until a stable nucleus is achieved. These four chains of consecutive parent and daughter nuclei (shown in the ) begin ...
radioactivity: property exhibited by certain types of matter of emitting energy and subatomic particles spontaneously. It is, in essence, an attribute of individual atomic nuclei.
radiolarian: any protozoan of the class Polycystinea (superclass Actinopoda), found in the upper layers of all oceans. Radiolarians, which are mostly spherically symmetrical, are known for their complex and beautifully sculptured, though minute, skeletons, referred to as tests. Usually composed of ...