Yeager Vya-gorV, Chuck orig. Charles Elwood Yeager (b. Feb. 13, 1923, Myra, W.Va., U.S.) U.S. test pilot. He served as a fighter pilot in World War II and became a flight instructor and test pilot after the war. Chosen to test-fly the secret experimental X-l aircraft, on Oct. 14, 1947, he became the first person to break the sound barrier in flight, which was approximately 662 mph (1,066 km/hr) at an altitude of 40,000 ft (12,000 m). A brash and colourful personality, he retired with the rank of brigadier general in 1975 and received the Presidential Medal of Freedom in 1985.
year Time required for the Earth to travel once around the Sun, slightly less than 36514 days. This fractional number makes necessary the peri¬ odic adjustment of days in any calendar that is to be kept in step with the seasons. In the Gregorian calendar, a common year contains 365 days, and every fourth year is a leap year of 366 days except for any year that is divisible by 100 but not divisible by 400 (e.g., 1900 was not a leap year).
Year 2000 bug See Y2K bug
yeast Any of certain economically important and usually single-celled fungi (see fungus), most of which are classified as ascomycetes. Found worldwide in soils and on plant surfaces, yeasts are especially abundant in sugary mediums such as flower nectar and fruits. The types commonly used in the production of bread, beer, and wine are selected strains of Saccharomyces cerevisiae, the small cakes and packets used contain bil¬ lions of individual yeast cells, each of which can ferment approximately its own weight of glucose per hour. Dried yeast is 50% protein and is rich in B vitamins; brewer’s yeast is sometimes taken as a vitamin supple¬ ment. Some yeasts are mild to dangerous pathogens of humans and other animals. Candida albicans, for example, irritates oral and vaginal linings, and Histoplasma and Blastomyces cause persistent lung infections.
Yeats \'yats\, William Butler (b. June 13, 1865, Sandymount, Dublin, Ire.—d. Jan. 28, 1939, Roquebrune-Cap-Martin, France) Irish poet, dra¬ matist, and prose writer. The son of a well-known painter, Yeats early developed an interest in mysticism and visionary traditions as well as in Irish folklore, and both interests would continue to be sources of poetic imagery for him. His early volumes include the poetry volume The Wan¬ derings of Oisin (1889) and the essay collection The Celtic Twilight (1893). In 1889 he fell in love with Maud Gonne, a brilliant, beautiful Irish patriot who inspired his involvement in Irish nationalism but did not recip¬ rocate his feelings. With Lady Augusta Gregory and others, he founded the theatre that became the Abbey Theatre; throughout his life he would remain one of its directors. He contributed plays to its repertoire, including The Countess Cathleen (1899), On Baile’s Strand (1905), and Deirdre (1907). His poetry changed decisively in the years 1909-14: the other¬ worldly, ecstatic atmosphere of the early lyrics cleared and his work gained in concreteness and complexity, often dealing with political themes, though his interest in mysticism and his passion for Maud Gonne continued unabated. With Responsibilities (1914) and The Wild Swans at Coole (1917) he began the period of his highest achievement. Some of his greatest verse appeal's in The Tower { 1928), The Winding Stair (1929), and Last Poems (1939). The individual poems of the latter are largely held together by the system of symbolism he developed in A Vision (1925), which used astrological images to link individual psychology with the larger patterns of history. Yeats was a member of the Irish Senate (1922- 28). He won the Nobel Prize for Literature in 1923, and he is regarded by some as the greatest English-language poet of the 20th century.
Yeh-lii Ch'u-ts'ai See Yelu Chucai
Yekaterinburg \yi-,ka-ti-ran-'hQrk\ formerly (1924-91) Sverd¬ lovsk \sfyird-'lofsk\ City (pop., 2001 est.: 1,256,900), west-central Rus-
Yarrow (Achillea millefolium variety lanulosa )
DENNIS E. ANDERSON
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Yelizavetpol ► Yeltsin I 2093
sia. An ironworks was established in 1721, and a fortress, named after Empress Catherine I, was founded there in 1722. It grew as the centre for all the ironworks of the Ural Mountains region, and its importance increased with the building of a highway (1783) and the Trans-Siberian Railroad. It achieved notoriety as the place where Tsar Nicholas II and his family were held prisoner and executed by the Bolsheviks in 1918. In 1924 it was renamed Sverdlovsk in honour of Yakov Sverdlov. The city reverted to its original name after the breakup of the U.S.S.R. in 1991. It is a major industrial centre, especially for heavy machinery.
Yelizavetpol See Ganca yellow bunting See yellowhammer
Yellow Emperor See Huangdi
yellow fever Acute infectious tropical disease, sometimes occurring in temperate zones. Abrupt onset of headache, backache, fever, nausea, and vomiting is followed by either recovery with immunity or by higher fever, slow pulse, and vomiting of blood. Patients may die in a week. Jaundice is common (hence the name). One of the world’s great plagues for 300 years, it is caused by a virus transmitted by several species of mosquitoes. Carlos Finlay suggested and Walter Reed proved this means of spread, leading to near elimination of the disease through mosquito control (see William Gor- gas). Treatment consists of supportive care, particularly fever reduction. Control of mosquitoes near cities and live-virus vaccines—developed by Max Theiler (1899-1972), who won a 1951 Nobel Prize for his work— have made yellow fever completely preventable.
yellow jacket Any of 35-40 species (genus Dolichovespula or Vesp- ula ) of social wasps, principally of the Northern Hemisphere, named for the black bands on its yellow abdomen. They differ from other wasps in having their wings folded longitudinally when at rest. Dolichovespula species typically build exposed nests. Vespula species build concealed nests underground or in protected cavities; when a nest is stepped on, the colony may erupt in an angry, stinging swarm. Nest size varies widely; some nests can be held in one hand, whereas nests in warmer climates may weigh half a ton.
yellow journalism In newspaper publishing, the use of lurid features and sensationalized news in newspaper publishing to attract readers and increase circulation. The phrase was coined in the 1890s to describe tac¬ tics employed in the furious competition between two New York papers, Joseph Puutzer’s World and William Randolph Hearst’s Journal. When Hearst hired away from Pulitzer a cartoonist who had drawn the immensely popular comic strip “The Yellow Kid,” another cartoonist was hired to draw the comic for the World ; the rivalry excited so much atten¬ tion that the competition was dubbed yellow journalism. Techniques of the period that became permanent features of U.S. journalism include banner headlines, coloured comics, and copious illustrations.
yellow poplar See tulip tree Yellow River See Huang He
Yellow Sea Chinese Huang Hai Vhwaq-'hlX Large inlet of the west¬ ern North Pacific Ocean, between northeastern China and the Korean peninsula. Renowned for its fishing grounds, it connects with the East China Sea on the south; the Shandong Peninsula extends into it from the west. Two major arms of it are the Bo Hai (northwest) and Korea Bay (north). Excluding the Bo Hai, it has an area of about 161,000 sq mi (417,000 sq km) and a maximum depth of 338 ft (103 m). It derives its name from the colour of the silt-laden water discharged into it by major Chinese rivers, including the Liao and the Huang He (Yellow River), both of which flow into the Bo Hai. Leading port cities include Qingdao and Dalian in China, Inch'on in South Korea, and Namp’o in North Korea.
Yellow Turbans Chinese secret society founded during a time of pes¬ tilence (2nd century ad). The rebels’ yellow headdresses signified their association with the earth element, which they believed would succeed the (red) fire element that represented Han rule. The sect was Daoist in inspiration, like the contemporaneous Five Pecks of Rice sect. Its rebellion (ad 184-c. 204) against the tyrannical eunuchs who influenced the emperor contributed to the fall of the Han dynasty. See also Daoism.