defecation \,def-3-'ka-sh9n\ or bowel movement Elimination of feces from the digestive tract. Peristalsis moves feces through the colon to the rectum, where they stimulate the urge to defecate. The rectum short¬ ens, pushing the feces into the anal canal, where internal and external sphincters allow them to be passed or retained. Chest, abdominal, and pelvic muscles are used to pass them. Long delay of defecation causes constipation and hardened feces. See also diarrhea, incontinence.
defense economics Field of national economic management con¬ cerned with peacetime and wartime military expenditures. It arose in response to the greater scale and sophistication of warfare in the 20th century. Most nations seek to avoid the vast financial and human costs of war—which include the lost earnings of those killed or injured, lifetime medical care needed for those permanently incapacitated, and losses to the economy caused by diverting resources from investments in future economic capacity—by maintaining a level of military preparedness suf¬ ficient to deter aggressors. Peacetime defense economics focuses on issues of allocation of resources between the military and civilian sectors, the relative size and character of the various armed forces, and the choice and design of their weapons.
defense mechanism In psychoanalytic theory, an often unconscious mental process (such as repression) that makes possible compromise solu¬ tions to personal problems or conflicts. The compromise generally involves concealing from oneself internal drives or feelings that threaten to lower self-esteem or provoke anxiety. The term was first used by Sig¬ mund Freud in 1894. The major defense mechanisms are repression, the process by which unacceptable desires or impulses are excluded from con¬ sciousness; reaction formation, a mental or emotional response that rep¬ resents the opposite of what one really feels; projection, the attribution of one’s own ideas, feelings, or attitudes (especially blame, guilt, or sense of responsibility) to others; regression, reversion to an earlier mental or behavioral level; denial, the refusal to accept the existence of a painful fact; rationalization, the substitution of rational and creditable motives for the true (but threatening) ones; and sublimation, the diversion of an instinc¬ tual desire or impulse from its primitive form to a more socially or cul¬ turally acceptable form. See also ego; neurosis; psychoanalysis.
deficit financing In government, the practice of spending more money than is received as revenue, the difference being made up by borrowing or minting new funds. The term usually refers to a conscious attempt to stimulate the economy by lowering tax rates or increasing government expenditures. Critics of deficit financing regularly denounce it as an example of shortsighted government policy. Advocates argue that it can be used successfully in response to a recession or depression, proposing that the ideal of an annually balanced budget should give way to that of a budget balanced over the span of a business cycle. See also John May¬ nard Keynes; national debt.
definition In philosophy, the specification of the meaning of an expres¬ sion relative to a language. Definitions may be classified as lexical, osten- sive, and stipulative. Lexical definition specifies the meaning of an expression by stating it in terms of other expressions whose meaning is assumed to be known (e.g., a ewe is a female sheep). Ostensive defini¬ tion specifies the meaning of an expression by pointing to examples of things to which the expression applies (e.g., green is the color of grass, limes, lily pads, and emeralds). Stipulative definition assigns a new mean¬ ing to an expression (or a meaning to a new expression); the expression defined (definiendum) may either be a new expression that is being intro¬ duced into the language for the first time, or an expression that is already current.
deflation Contraction in the volume of available money or credit that results in a general decline in prices. A less extreme condition is known as disinflation. Attempts are sometimes made to bring on deflation (through raising interest rates and tightening the money supply) in order to combat inflation and slow the economy. Deflation is characteristic of depressions and RECESSIONS.
Defoe \di-'fo\, Daniel orig. Daniel Foe (b. 1660, London, Eng.—d. April 24, 1731, London) British nov¬ elist, pamphleteer, and journalist. A well-educated London merchant, he became an acute economic theorist and began to write eloquent, witty, often audacious tracts on public affairs. A satire he published resulted in his being imprisoned in 1703, and his business collapsed. He traveled as a government secret agent while continuing to write prolifically. In 1704-13 he wrote practically single- handedly the periodical Review, a serious and forceful paper that influ¬ enced later essay periodicals such as The Spectator. His Tour Through the Whole Island of Great Britain, 3 vol.
(1724-26), followed several trips to Scotland. Late in life he turned to fic¬ tion. He achieved literary immortal¬ ity with the novel Robinson Crusoe (1719), which drew partly on mem¬ oirs of voyagers and castaways. He is also remembered for the vivid, picaresque Moll Flanders (1722); the nonfictional Journal of the Plague Year (1722), on the Great Plague in London in 1664-65; and Roxana (1724), a prototype of the modem novel.
defoliant Chemical dust or spray applied to plants to cause their leaves to drop off prematurely. Defoliants sometimes are applied to crop plants such as cotton to facilitate harvesting. They have also been used in war¬ fare to eliminate enemy food crops and potential areas of concealment (as in the Vietnam War). See also Agent Orange.
deforestation Process of clearing forests. Rates of deforestation are particularly high in the tropics, where the poor quality of the soil has led to the practice of routine clear-cutting to make new soil available for agri¬ cultural use. Deforestation can lead to erosion, drought, loss of biodiver¬ sity through extinction of plant and animal species, and increased atmospheric carbon dioxide. Many nations have undertaken afforestation or reforestation projects to reverse the effects of deforestation, or to increase available timber. See also greenhouse effect.
deformation and flow Alteration in size or shape of a body under the influence of mechanical forces. Flow is a change in deformation that continues as long as the force is applied. Gases and liquids normally flow relatively freely, while solids deform when subjected to forces. Most sol¬ ids initially deform elastically (see elasticity), though rigid material such as metals, concrete, or rocks can sustain large forces while undergoing little deformation. If enough force is applied, even these materials will reach their elastic limit, at which point brittle substances fracture while ductile materials (see ductility) rearrange their internal structure, the result being plastic deformation (see plasticity).
Degas \d3-'ga\, (Hilaire-Germain-) Edgar (b. July 19,1834, Paris, France—d. Sept. 27, 1917, Paris) French painter, graphic artist, and sculp¬ tor. The son of a wealthy banker, he entered the Ecole des Beaux-Arts in 1855. He spent much time in Italy studying and copying the Old Masters and became a skilled draftsman, producing history paintings and portraits. In the 1860s he was introduced to Impressionism by Edouard Manet and gave up his academic aspirations, turning for his subject matter to the fast-moving city life of Paris, particularly the ballet, theatre, circus, race¬ track, and cafes. Influenced by Japanese prints and the new medium of photography, he used displaced figure groupings and unfamiliar perspec¬ tive to create figure groups seen informally and in movement, similar in effect to snapshots. His fascination with the ballet and the racetrack sprang from his interest in picturing people absorbed in the practiced movements of their occupations. He often worked in pastel, his favourite medium, producing series of women, bathers, ballerinas, and horse races. From c.