( Umar Tal \,u-mar-'tal\ in full al-Hajj ‘Umar ibn SaTd Tal (b. c.
1797, Halvar, Fouta-Toro [Senegal]—d. Feb. 12, 1864, near Hamdalahi, Tukulor empire [Mali]) West African founder of the Tukulor empire. Bom in the Senegal River valley, he became a mystic and set out to Mecca on a pilgrimage at age 23. Through political and religious connections he made during and after his journey, he was appointed caliph for black Africa by the head of the TijanI brotherhood. He returned to Africa in
1833, and in 1854, in the area of upper Guinea, eastern Senegal, and western and central Mali, he ordered a jihad to sweep away the pagans and bring back lapsed Muslims. He defeated the Bambara pagans of Mali, but they soon rebelled. Attacked by the Tuaregs, Moors, and Fulani in 1863, 'Umar’s army was destroyed, and he was pursued and killed in an explosion. His empire lasted under his son Ahmadu Seku until 1897, when it was annexed by the French.
Umayyad \u-'ma-yod\ dynasty (661-750) First great Muslim dynasty. It was founded by Mu'awiyah I, who triumphed over the Prophet Muhammad’s son-in-law, c AlT, to become the fifth caliph. He moved the capital from Medina to Damascus and used the Syrian army to extend the Arab empire. The Umayyads’ greatest period was under Abd al-Malik (r. 685-705), when their empire extended from Spain to Central Asia and India. Their decline began with a defeat by the Byzantine Empire in 717; intertribal feuding, discontent among non-Arab Muslim converts, and the failure of financial reforms eventually led to their unseating by the ‘Abbasid dynasty. See also c Abd al-Rahman III; AbG Muslim; al-HusAYN ibn ‘All
Umberto I (b. March 14, 1844, Turin, Piedmont, Kingdom of Sardinia—d. July 29, 1900, Monza, Italy) King of Italy (1878-1900) and duke of Savoy. The son of Victor Emmanuel II, he fought in the wars against Austria (1866). After ascending the throne in 1878, he led his country out of its isolation and into the Triple Alliance (1882). However, a tariff war with France led to economic difficulties (1888), and Umberto’s colonial policy in Africa was ended by Italy’s defeat by Ethiopia (1896). Facing increasing social unrest, he supported the imposition of martial law (1898) and created a period of turmoil that culminated in his assassination by an anarchist.
Umberto II (b. Sept. 15, 1904, Racconigi, Italy—d. March 18, 1983, Geneva, Switz.) Prince of Savoy and briefly king of Italy (1946). Son of Victor Emmanuel III, he commanded an Italian army division in World War II. In May 1946 his father abdicated in his favour, but Umberto was him¬ self forced to abdicate in June after the Italian people voted for a repub¬ lic. He and his male heirs were permanently banished from Italy (though the ban was lifted in 2002), and he settled in Portugal.
Umbria Region (pop., 2001 prelim.: 815,588), central Italy. It is located on 3,265 sq mi (8,456 sq km) in the Apennines; its capital is Perugia. Originally inhabited by the ancient Italic Umbrian tribe, it came under Rome c. 300 bc and was made one of its administrative regions in the 1st century ad. During the Christian era it became part of the Papal States. It was the seat of the 15th-16th-century Umbrian school of painting, which included Perugino and Pinturicchio, and was the home of St. Francis of Assisi. Agriculture is an economic mainstay, while its industries produce steel, chemicals, and textiles.
Umbrian Any member of an ancient pre-Etruscan people pushed into central Italy (Umbria) by the Etruscans and Gauls. They never fought an important war with the Romans. In the Social War they were among the first to make peace with Rome. They are described by ancient authors as being similar to their Etruscan enemies in culture. The Umbrian alphabet is undoubtedly of Etruscan origin. Their dialect was Indo-European.
Umbrian Vsm-bre-onV language Ancient Italic language spoken in central Italy in the last few centuries bc. Umbrian was related closely to Oscan and Volscian and more distantly to Latin. It was displaced by Latin at an unknown date. Modern knowledge of the language is derived almost entirely from the Iguvine Tables (c. 300-90 bc).
UN See United Nations
Un-American Activities Committee, House See House Un-American Activities Committee
Unabomber See Theodore Kaczynski
Unamuno V.ii-na-'mu-noX (y Jugo), Miguel de (b. Sept. 29, 1864, Bilbao, Spain—d. Dec. 31, 1936, Salamanca) Spanish philosopher and writer. He served twice as rector of the University of Salamanca (1901— 14; 1931-36); he was dismissed first for espousing the Allied cause in World War I and later for denouncing Francisco Franco’s Falangists. Though he also wrote poetry and plays, he was most influential as an essayist and novelist. In The Tragic Sense of Life in Men and Peoples (1913), he stressed the role spiritual anxiety plays in driving one to live the fullest possible life. His most famous novel is Abel Sanchez (1917), a modem re-creation of the biblical story of Cain and Abel. The Christ of Velazquez (1920), a study in poetic form of the great Spanish painter, is a superb example of modem Spanish verse.
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1962 I uncertainty principle ► ungulate
uncertainty principle or Heisenberg uncertainty principle or indeterminacy principle Principle that states that the position and velocity of an object cannot both be measured exactly at the same time, and that the concepts of exact position and exact velocity together have no meaning in nature. Articulated by Werner Heisenberg in 1927, it applies only at the small scales of atoms and subatomic particles and is not notice¬ able for macroscopic objects, such as moving vehicles. Any attempt to measure the velocity of a subatomic particle precisely will displace the particle in an unpredictable way, thus invalidating any simultaneous mea¬ surement of its position. This displacement is a result of the wave nature of particles (see wave-particle duality). The principle also applies to other related pairs of variables, such as energy and time.
Uncle Sam Popular U.S. symbol, usually associated with a cartoon fig¬ ure having long white hair and chin whiskers and dressed in a swallow¬ tailed coat, vest, tall hat, and striped trousers. The name probably origi¬ nated with “Uncle Sam” Wilson, a businessman who provided beef to the army during the War of 1812.
The “U.S.” stamp on his barrels, meant to indicate government prop¬ erty, came to be associated with his nickname, which in time came to symbolize the U.S. government. The Uncle Sam figure evolved in the hands of British and U.S. cartoon¬ ists; its most familiar treatment appeared on recruiting posters dur¬ ing World Wars I and II with the cap¬ tion “I want you.”
unconscious or subconscious
In psychoanalysis, the part of the psy¬ chic apparatus that does not ordi¬ narily enter the individual’s awareness but may be manifested by slips of the tongue, dreams, or neurotic symptoms (see neurosis). The existence of unconscious mental activities was first elaborated by Sigmund Freud and is now a well-established principle of psychiatry. The origin of many neurotic symptoms is said to depend on conflicts that have been removed from consciousness by repression and maintained in the uncon¬ scious through various defense mechanisms. Recent biopsychological explo¬ rations have shed light on the relationship between brain physiology and the levels of consciousness at which people retain memories.
underground See subway Underground See Resistance
Underground Railroad Secret system in northern U.S. states to help escaping slaves. Its name derived from the need for secrecy and the railway terms used in the conduct of the system. Various routes in 14 states, called lines, provided safe stopping places (stations) for the leaders (conductors) and their charges (packages) while fleeing north, sometimes to Canada. The system developed in defiance of the Fugitive Slave Acts and was active mainly from 1830 to 1860. An estimated 40,000 to 100,000 slaves used the network. Assistance was provided mainly by free blacks, including Harriet Tubman, and philanthropists, church leaders, and abolitionists. Its existence aroused support for the antislavery cause and convinced Southerners that the North would never allow slavery to remain unchallenged.