yard Unit of length equal to 36 iNCHes, or 3 feet (see foot), in the U.S. Customary System or 0.9144 metre in the International System of Units. A cloth yard, used to measure cloth, is 37 in. long; it was also the standard length for arrows. In casual speech, a yard (e.g., of concrete, gravel, or topsoil) may refer to a cubic yard.
Yarmuk \yar-'muk\ River River, northwestern Jordan. It rises in south¬ western Syria and flows southwest to its confluence with the Jordan River. For most of its total course of about 50 mi (80 km), it forms the bound¬ ary between Syria and Jordan. A major battle along the river between invading Muslim Arabs and Byzantine forces in 636 ad established Mus¬ lim dominance in Palestine. That dominance, broken only by the period of the Crusades (1099-1291), lasted until World War I (1914-18). Since the Six-Day War of 1967, the lower river valley has been under Israeli control.
yarn Continuous strand of fibres grouped or twisted together and used to construct textile fabrics. Yams are made from both natural and synthetic fibres, in filament or staple form. Filament is very long fibre, including the natural fibre SILK and the synthetic fibres. Most fibres that occur in nature are fairly short, or staple, and synthetic fibres may be cut into short, uniform lengths to form staple. Spinning is the process of drawing out and twisting a mass of cleaned, prepared fibres. Filament yarns generally require less twist than do staple yarns. More twist produces stronger yam; low twist produces softer, shinier yam. Two or more single strands may be twisted together to form ply yarn. Knitting yams have less twist than weaving yams. Thread, used for sewing, is a tightly twisted ply yarn.
Yaroslav \y3-re-'slaf\ known as Yaroslav the Wise (b. 980—d. Feb. 2, 1054) Grand prince of Kiev (1019-54). A son of Vladimir I, he defeated
his brother Svyatopolk the Accursed to become ruler of Kiev. He consoli¬ dated the state through administra¬ tive reforms and military campaigns, codified laws, and promoted the spread of Christianity. He also built many fortifications and churches in the Byzantine style, including the Cathedral of St. Sophia. Yaroslav regained Galicia from the Poles and expanded Kievan possessions in the Baltic region, but his military cam¬ paign against Constantinople was a failure (1043).
Yarqon \yar-'kon\ River River, west-central Israel. It rises near Rosh Ha-Ayin and flows westward for about 16 mi (26 km) to the Mediter¬ ranean Sea near northern Tel Aviv- Jaffa. It marks the boundary between the Plain of Sharon and the coastal
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Yao, imaginative portrait by an artist of the Ch'ien-lung period (1735-96); in the Metropolitan Museum of Art, New York City.
COURTESY OF THE METROPOLITAN MUSEUM OF ART, NEW YORK, GIF OF MRS. EDWARD S. HARKNESS, 1947
© 2006 Encyclopaedia Britannica, Inc.
2092 I yarrow ► Yekaterinburg
lowlands. Since the construction and expansion of the Yarqon-Negev Project in the 1950s (see Negev), the water level has gone down, and pol¬ lution has increased. During World War I (1914-18), it was the site of several important British victories over the Ottoman Empire in the Allied Powers’ conquest of Palestine.
yarrow \'yar-o\ Any of about 80 species of perennial herbs that make up the genus Achillea in the compos¬ ite family, native mainly to the north¬ ern temperate zone. Some species are cultivated as garden ornamentals.
They have toothed, often finely cut, sometimes aromatic leaves. Many small white, yellow, or pink flowers are often grouped into flat-topped clusters, which can be dried for win¬ ter bouquets.
Yasin \ya-'sen\, ‘Abd al-Salam
(b. 1928) Moroccan religious leader.
A former school inspector fluent in English and French, he began prac¬ ticing Sufism in the 1960s. By the early 1970s he had adopted a more political view of Islam and was influ¬ enced by the writings of the Egyp¬ tian Islamists Hasan al-BANNA and Sayyid Qujb. After sending a letter to the king of Morocco advocating the establishment of an Islamic state—a consistent theme in his work—he was confined to a mental institution (1974-77), and in 1986 he founded a movement, Charity and Justice. From 1989 he was under house arrest.
yaws or frambesia \fram-'be-zho\ Contagious tropical disease, caused by a variant of the spirochete that causes syphilis. Yaws spreads mainly by discharge from skin sores, not sexual activity. It is common in children, who usually become immune. In the first stage, a skin sore starts as a wartlike thickening, cracks open, leaks fluid, and bleeds easily. A month or more later, multiple sores erupt. The third stage (much rarer than in syphilis) involves destruction of skin, mucous membranes, and bones. Penicillin cures early-stage yaws. Prevention requires isolation and prompt treatment and personal and group hygiene.
Yayoi Vya-,y6i\ culture (c. 250 bc-c. ad 250) Prehistoric culture of Japan subsequent to Jomon culture. It arose on the island of Kyushu and spread northeastward across Honshu. The Yayoi people mastered bronze and iron casting, wove hemp, and employed a Chinese method of wet- paddy rice cultivation. Yayoi pottery is unglazed; early examples have incised decorations, but pieces produced in the last stage of the period are often undecorated. Chinese-style bronze mirrors and coins indicate con¬ tact with Han-dynasty China.
YazTd \ya-'zed\ I (b. c. 645, Arabian Peninsula—d. 683, Damascus, Syria) Second caliph (680-683) of the Umayyad dynasty. He oversaw the events at the Battle of Karbala’ (680), which contributed to the eventual split of Islam into Sunnite and ShTite sects. He succeeded his father, Mua'wiyah I, as caliph, keeping Mua'wiyah’s advisers and retaining most of his policies, while reforming the financial system, adjusting tax policy, and improving the irrigation system of the Damascus oasis. See also fit- nah; al-HusAYN ibn c Au.
YazTdi \'ya-zi-de\ Middle Eastern religion, a syncretic combination of Zoroastrian, Manichaean, Jewish, Nestorian Christian, and Islamic ele¬ ments. Its adherents, numbering fewer than 100,000, are found in Iraq, Turkey, Syria, Armenia, the Caucasus, and Iran. Most speak Kurdish. They believe that they were created separately from the rest of human¬ kind and segregate themselves from the rest of society. In Yazld! belief, seven angels, subordinate to a supreme but uninvolved God, rule the uni¬ verse. The belief that God restored the Devil to his position as chief of the angels upon the Devil’s repentance has earned the Yazld! an unde¬ served reputation as Devil worshipers. Their chief saint is Sheikh c AdI, a 12th-century Muslim mystic. Their name derives from YazId I (c. 645- 683), from whose supporters they may be descended.
Yazoo land fraud \ya-'zii\ (1795-1814) Scheme to sell land in Geor¬ gia. After legislators were bribed to sell Georgia’s western land claims
around the Yazoo River to four land companies for $500,000, public anger forced a newly elected Georgia legislature to rescind the act (1796) and return the money. Much of the land had meanwhile been resold to third parties, who refused the money and maintained their claim to the prop¬ erty. The state ceded its claim to the U.S. in 1802. In 1810 the U.S. Supreme Court ruled that the 1796 rescinding law was an unconstitutional infringement on a contract. By 1814 the U.S. government assumed pos¬ session of the territory and awarded the claimants over $4 million.
Yazoo \ya-'zii\ River River, west-central Mississippi, U.S. Formed by the confluence of the Tallahatchie and Yalobusha rivers north of Green¬ wood, Miss., it meanders 189 mi (304 km) south and southwest to join the Mississippi River above Vicksburg. Its basin is protected from flooding by an extensive system of levees.