asymmetric synthesis Chemical reaction by which unequal amounts of two product isomers are formed. It is normally not possible to synthe¬ size from materials that do not have optical activity (i.e., are not chiral) one stereoisomer of a chiral compound without the other, but use of a chiral auxiliary, such as an enzyme or other catalyst, a solvent, or an intermedi¬ ate, can force the reaction to produce predominantly or only one isomer. Asymmetric syntheses are often called stereoselective; if one product forms exclusively, it is stereospecific.
asymptote Va-som-.toA In mathematics, a line or curve that acts as the limit of another line or curve. For example, a descending curve that approaches but does not reach the horizontal axis is said to be asymptotic to that axis, which is the asymptote of the curve.
AT&T Inc. formerly American Telephone and Telegraph Co.
U.S. telecommunications corporation. It was established as a subsidiary of Bell Telephone Co. (founded by Alexander Graham Bell in 1877) to build long-distance telephone lines and later became the parent company of the Bell System. In the early 20th century it gained a virtual monopoly over the U.S. telecommunications industry, and by 1970 it was the world’s largest corporation. It developed transoceanic radiotelephone links and
Miguel Angel Asturias.
CAMERA PRESS
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Atacama ► Atget I 123
telephone cable systems and created the Telstar satellite communications system. Years of federal antitrust litigation resulted in 1984 in the divest¬ ment by AT&T (nicknamed “Ma Bell”) of its 22 regional telephone com¬ panies, which were combined to form seven “Baby Bells”: Nynex, Bell Atlantic, Ameritech, BellSouth, Southwestern Bell Corp. (renamed SBC Corp. in 1995), US West, and Pacific Telesis Group. Although several Baby Bells merged following the Telecommunications Act of 1996, AT&T proceeded to divide its operations into three separate companies: AT&T Corp., Lucent Technologies Inc. (composed of the former operations of Western Electric and Bell Laboratories), and the NCR Corp. In 2005 AT&T was acquired by SBC Corp., which then changed its name to AT&T Inc. Its diversified telecommunications businesses included local and long¬ distance telephone service, wireless voice and data networks, broadband DSL (Digital Subscriber Line), and Internet communication and Web man¬ agement services.
Atacama \,a-ta-'ka-ma\ Desert Cool, arid area, north-central Chile. Extending north from the city of Copiapo, the area runs from north to south for a distance of some 600 to 700 mi (1,000 to 1,100 km) and cov¬ ers most of the Antofagasta region and the northern part of the Atacama region. Because of its location between low coastal mountains and a higher inland range, the region is meteorologically anomalous. Despite its low latitude, summer temperatures average only about 65 °F (18 °C), and, though heavy fogs are common, the desert is one of the driest regions in the world. Some areas receive heavy rain only two to four times a cen¬ tury. For much of the 19th century, the desert was the object of conflicts between Chile, Bolivia, and Peru; after the War of the Pacific (1879-83), Chile emerged with permanent ownership of sectors previously controlled by Peru and Bolivia. For years before the development of synthetic meth¬ ods of fixing nitrogen, the desert was a chief source of the world’s nitrates.
Atahuallpa \,a-ta-'wal-pa\ (b. c. 1502—d. Aug. 29, 1533, Cajamarca, Inca empire) Last free-reigning emperor of the Incas. He became ruler after defeating his half brother in what may have been the greatest mili¬ tary engagement in Inca history. The conquistador Francisco Pizarro met Atahuallpa just before the emperor’s triumphal entry into Cuzco and invited him to a feast in his honour. When Atahuallpa and his unarmed retainers arrived, Pizarro ambushed them on horseback with cannons and guns, slaughtered thousands, and took Atahuallpa prisoner. Pizarro accepted Atahuallpa’s offer of a ransom of a roomful of gold; then, hav¬ ing received 24 tons of gold and silver, he ordered Atahuallpa burned at the stake. The sentence was changed to death by garrote when Atahuall¬ pa agreed to convert to Christianity.
Atalanta \,a-t 3 l-'an-t9\ In Greek mythology, a swift-footed huntress. Born in Boeotia or Arcadia, she was left to die at birth but was suckled by a bear.
As an adult she took part in the famous Calydonian boar hunt and drew first blood. She offered to marry any man who could outrun her in a race, but the losers were required to pay with their lives. One contes¬ tant, Hippomenes (or Milanion), obtained three golden apples from Aphrodite to carry in the race. As he dropped them, Atalanta stooped to pick them up, and thus lost the race.
The two were later turned into lions after they desecrated a shrine to Cybele or Zeus.
Atanasoff Vo-'tan-o-.soA, John V(incent) (b. Oct. 4, 1903, Hamil¬ ton, N.Y., U.S.—d. June 15, 1995,
Frederick, Md.) U.S. physicist. He received his Ph.D. from the Univer¬ sity of Wisconsin. With Clifford Berry, he developed the Atanasoff-Berry Computer (1937-42), a machine capable of solving differential equations using binary arithmetic. In 1941 he joined the Naval Ordnance Labora¬ tory; he participated in the atomic bomb tests at Bikini Atoll (1946). In 1952 he established the Ordnance Engineering Co., which he later sold to Aerojet Engineering Corp. In 1973, after a judge voided a patent owned by Sperry Rand Corp. on ENIAC, the Atanasoff-Berry Computer was credited as the first electronic digital computer.
Atargatis \3-'tar-go-tis\ Goddess of northern Syria who was worshiped at Hierapolis, northeast of Aleppo, along with her consort, Hadad. Pri¬ marily a goddess of fertility, she was also mistress of the city and its people. She was often depicted wearing a crown and carrying a sheaf of grain, and her throne was supported by lions, suggesting her power over nature. Considered a combination of Anath and Astarte, she also showed kinship with the Anatolian Cybele (Great Mother of the Gods). Merchants and mercenaries carried her cult throughout the Greek world, where she was considered a form of Aphrodite.
Ataturk Yat-s-.torkV Mustafa Kemal orig. Mustafa Kemal (b.
1881, Salonika, Greece, Ottoman Empire—d. Nov. 10, 1938, Istanbul, Tur.) Founder of modem Turkey. Dedicated by his father to military ser¬ vice, he graduated near the top of his class in military school. As a young officer, he was critical of the government of the Ottoman Empire and became involved with the Turkish nationalist Committee of Union and Progress. He nevertheless fought for the government during World War I (1914-18), achieving great success against Allied forces during the Dardanelles Cam¬ paign. The eventual Allied victory brought British, French, and Italian troops to Anatolia; appointed to restore order there, he used the opportunity to incite the people against the Allied occupation. Greece and Armenia, ter¬ ritorial beneficiaries of the Ottoman defeat, opposed the Turkish national¬ ists, but Mustafa Kemal overcame all opposition, and the Republic of Turkey was established in 1923. He was given the name Ataturk (“Father of the Turks”) in 1934. He pursued a policy of Westernization and secu¬ larization, in which Western styles of dress and appellation were made mandatory, seclusion of women was abolished, and the legal and educa¬ tional system was overhauled. See also Enver Pasha; Young Turks.
ataxia \a-'tak-se-9\ Inability to coordinate voluntary muscular move¬ ments. In common usage, the term describes an unsteady gait. Hereditary ataxias are usually caused by degeneration of the spinal cord, cerebellum, or other parts of the nervous system. The most common is Friedreich ataxia, which begins at ages 3-5, progressing slowly to almost complete inca¬ pacity by age 20. There is no specific therapy. Metabolic disorders, brain injuries, and toxins can cause ataxia.