quadratic equation Algebraic equation of particular importance in optimization. A more descriptive name is second-degree polynomial equa¬ tion. Its standard form is ax 2 + bx + c = 0, and its solution is given by the quadratic formula
_ -b ± \/b 2 -4ac
X ~ (2a)
which guarantees two real-number solutions, one real-number solution, or two complex-number solutions, depending on whether the discriminate, b 2 - 4 ac, is greater than, equal to, or less than 0.
quadrille \kwa-'dril\ Dance for four couples in square formation, fash¬ ionable from the late 18th through the 19th century. Imported to England from Parisian ballrooms in 1815, it consisted of four or five contredanses (see country dance), each danced with prescribed combinations of inter¬ twining figures rather than depending on intricate individual steps. It was often danced to opera melodies. See also American square dance.
Quadros, Janio da Silva (b. Jan. 25, 1917, Campo Grande, Mato Grosso, Braz.—d. Feb. 16, 1992, Sao Paulo) President of Brazil (1961). A colourful and eccentric populist, he campaigned with a broom to dra¬ matize his pledge to “sweep out corruption.” In his seven months as president, he banned bikini swimsuits and cockfights, reestablished rela¬ tions with the Soviet Union, decorated Che Guevara, and refused to sup¬ port the U.S. in the Bay of Pigs invasion of Cuba. He attributed his sudden resignation to “terrible forces” conspiring against him. Stripped of politi¬ cal rights and exiled in 1968, he was granted amnesty in 1980 and returned to serve two terms as mayor of Sao Paulo.
Quadruple Alliance (1718) Alliance between Austria, Britain, the Dutch Republic, and France, formed to prevent Spain from altering the terms of the Peace of Utrecht (1713). When Philip V of Spain seized Sar¬ dinia and Sicily, the British fleet brought Austrian troops to Sicily and the French occupied northern Spain, and Philip was forced to renounce his claims in Italy.
Quadruple Alliance (1815) Alliance between Britain, Russia, Aus¬ tria, and Prussia first formed in 1813 to oppose France in the final phase of the Napoleonic Wars. It was officially renewed in 1815 to enforce the peace settlement concluded at the Congress of Vienna. The allies agreed to meet occasionally to keep European political development within terms of the 1815 settlement. This program was partially carried out by the Congresses of Aix-la-Chapelle (1818), Troppau (1820), Laibach (1821), and Verona (1822).
quaestor Vkwe-stor, 'kwe-stor\ Latin "investigator" In ancient Rome, the lowest ranking regular magistrate, whose traditional responsi¬ bility was the treasury. Quaestors functioned as deputies to consuls. Like
consuls, praetors, and prefects they were of the magistrate class, high-level government administrators. Quaestors were the lowest level of this class and were elected by the people. Initially they were appointed by the con¬ suls, but later they were elected. After 421 bc there were four quaestors, two public treasurers and two who assisted the consuls, serving as quar¬ termasters. From the time of Augustus, the number of quaestors increased to 20, many of whom acted as financial officers and assistants to provin¬ cial governors.
quahog Vko-.hog, l kw6- l hog\ Thick-shelled edible clam of the U.S. The northern quahog (Mercenaria mercenaria ), also known as the cherrystone, littleneck, or hard-shell clam, is 3-5 in. (8-13 cm) long. The dingy white shell is thick and rounded and has prominent concentric lines. It is found in the intertidal zone from the Gulf of St. Lawrence to the Gulf of Mexico. It is the most important food clam of the Atlantic coast. The southern qua¬ hog (M. campechiensis), found in the intertidal zone from Chesapeake Bay to the West Indies, is about 3-6 in. (8-15 cm) long and has a heavy, white, plump shell.
quail Any of several species of short-tailed game birds (family Phasi- anidae), some with a head plume that is straight or curled forward. Species range from 5 to 13 in. (13-33 cm) long. Some of the 95 Old World spe¬ cies have leg spurs, but the 36 New World species never do. Quails pre¬ fer open country and brushy borders.
The male may help incubate the 12 eggs. Quails mainly eat seeds and berries but also leaves, roots, and insects. The common quail ( Coturnix coturnix) of Eurasia and Africa is the only migratory bird in the order Gal- liformes. Quails are generally smaller than partridges. See also bob- white.
Quaker Oats Co. International manufacturer of grocery products. It was formed in 1901 by the merging of three milling companies from Ohio and Iowa, including the coun¬ try’s largest cereal mill. The com¬ pany initially produced oat and wheat cereals, cornmeal, and baby food. By the late 20th century, hun¬ dreds of food products had been added. In the 1960s and ’70s, the com¬ pany diversified into chemical products, restaurants, and toys. Quaker purchased Gatorade in 1983 and sold most of its nonfood assets in the 1990s. The company merged with PepsiCo, Inc., in 2001.
Quakers See Society of Friends
quality In philosophy, a property that applies to things taken singly, in contrast to a relation, which applies to things taken in pairs, triples, etc. The distinction drawn by Galileo and John Locke between primary and secondary qualities is motivated by the fact that modern science seems to reveal that unaided sensory perception gives false or incomplete infor¬ mation about the intrinsic qualities of physical objects. In this view, pri¬ mary qualities, such as shape, quantity, and motion, are genuine properties of things that are describable by mathematics, whereas secondary quali¬ ties, such as odour, taste, sound, and colour, exist only in human con¬ sciousness.
Quant, Mary (b. Feb. 11, 1934, London, Eng.) English fashion designer. Specializing in youth-oriented fashions, she was responsible in the 1960s for the “Chelsea look” of England and the widespread popu¬ larity of the miniskirt and “hot pants.” After opening a successful bou¬ tique called Bazaar in 1957, she went on to mass-produce her designs on a multimillion-dollar annual scale.
Quantrill Vkwan-trol\, William C(larke) (b. July 31, 1837, Canal Dover, Ohio, U.S.—d. June 6, 1865, Louisville, Ky.) U.S. outlaw and Confederate guerrilla. After working as an itinerant schoolteacher, he moved to Kansas, where he failed at farming. By 1860 he was a horse thief and murderer. In the American Civil War he joined the Confederate army and later gathered a gang of guerrillas to raid and rob Union towns
California quail (Callipepla californica).
© WILLIAM H. MULLINS, THE NATIONAL AUDUBON SOCIETY COLLECTION/PHOTO RESEARCHERS
© 2006 Encyclopaedia Britannica, Inc.
1574 I quantum ► quartz
and farms. Quantrill’s Raiders were made an official troop by the Con¬ federates in 1862. In 1863 Quantrill and his group of about 450 men sacked the free-state town of Lawrence, Kan., killing 150 people. They later defeated a Union detachment, killing 90 soldiers. Quantrill was mor¬ tally wounded in a raid into Kentucky.
quantum In physics, a discrete natural unit, or packet, of energy, charge, angular momentum, or other physical property. Light, for example, which appears in some respects as a continuous electromagnetic wave, on the submicroscopic level is emitted and absorbed in discrete amounts, or quanta; for light of a given wavelength, the magnitude of all the quanta emitted or absorbed is the same in both energy and momentum. These particlelike packets of light are called photons, a term also applicable to quanta of other forms of electromagnetic energy such as X rays and gamma rays. Submicroscopic mechanical vibrations in the layers of atoms com¬ prising crystals also give up or take on energy and momentum in quanta called phonons. See also quantum mechanics.
quantum chromodynamics (QCD) Theory that describes the action of the strong force. The strong force acts only on certain particles, principally quarks that are bound together in the protons and neutrons of the atomic nucleus, as well as in less stable, more exotic forms of matter. Quantum chromodynamics has been built on the concept that quarks inter¬ act via the strong force because they carry a form of “strong charge,” which has been given the name “colour.” The three types of charge are called red, green, and blue, in analogy to the primary colours of light, though there is no connection with the usual sense of colour.