Three Kingdoms (ad 220-80) Trio of warring Chinese states that fol¬ lowed the demise of the Han dynasty. Cao Cao put his son on the throne of the kingdom of Wei, which controlled northern China. The kingdom of Shu-Han was established in present-day Sichuan by Liu Bei and his adviser Zhuge Liang, and the kingdom of Wu was established in the south, with its capital at Nanjing. They were all subsumed into the Jin dynasty by ad 280. The 60 years of the Three Kingdoms have inspired Chinese literature, and especially historical fiction, ever since.
Three Mile Island Nuclear power station near Harrisburg, Pa., site of the most serious accident in the history of the U.S. nuclear power industry (March 28, 1979). Mechanical failures and human errors caused a partial meltdown of the nuclear core and the release of radioactive gases. Despite assurances that there had been little risk to people’s health, the accident increased public fears about the safety of nuclear power and strengthened public opposition to its use, effectively stopping construction of nuclear reactors and further development of U.S. nuclear power plants.
Three Stooges U.S. comedy team. It was originally formed as a vaude¬ ville team in 1923 by brothers Moe and Shemp Howard (1897-1975, 1900-55), who performed with “Ted Healy and His Stooges.” In 1928 the brothers added Larry Fine (1911-74) to the act, which appeared in Broad¬ way revues. After Shemp left the act (1930), he was replaced by his brother Curly (1906-52). They appeared in several feature films, and in 1934 they began a series of comedy shorts that numbered more than 200 when they ceased in 1958. Their films were characterized by violent slapstick.
3M Co. U.S. corporation headquartered in St. Paul, Minn., manufactur¬ ing a wide range of products. It was incorporated as Minnesota Mining and Manufacturing Co. in 1902; its first product was sandpaper. It grew steadily, adding the original cellophane tape, Scotch tape, as well as mask¬ ing tape to its product line. Other innovations included the widely used Post-it notes, introduced in 1980. 3M’s products include photographic film, videocassettes, computer-synthesized graphics, and health-care products. It is notable among diversified U.S. corporations in that its growth has been primarily by internal means rather than by large-scale acquisitions.
threonine Vthre-3-,nen\ One of the essential amino acids. It occurs in the proteins of egg, milk, gelatin, and other biological substances and may
be synthesized or obtained by hydrolyzing casein. It is used in nutritional and biochemical research and as a dietary supplement.
thresher shark Any of five species (family Alopiidae) of sharks with a long, scythelike tail that may constitute almost half their total length. They are found in tropical and temperate seas worldwide. They eat squid and schooling fishes, attacking after circling and herding their prey into small groups. They sometimes use their tail to stun their prey or, by thrashing the water, to frighten them. They are not considered dangerous to humans. The long-tailed thresher, or fox shark (Alopias vulpinus), is a big, dark fish that grows about 20 ft (6 m) long.
thrips Any of some 5,000 species (order Thysanoptera) of tiny winged insects that feed chiefly on plants, inhabiting temperate and tropical areas worldwide. Many species damage cultivated plants, by either sucking the sap or transmitting viral plant diseases. A few species are predators. Thrips reach a maximum length of about half an inch (15 mm). Most have two pairs of long, narrow, hair-fringed wings.
thrombocyte See platelet
thrombosis \thram-'bo-s9s\ Formation of a blood clot (thrombus) in the heart or a blood vessel. Contributing factors include injury to a blood vessel’s lining from inflammation (thrombophlebitis) or atherosclerosis, blood flow that is turbulent (e.g., from an aneurysm) or sluggish (e.g., from prolonged bed rest), or coagulation abnormalities (e.g., from high num¬ bers of platelets or excessive fats in the blood). Thrombosis, especially in deep veins of the leg, is a particular danger after major surgery. A throm¬ bus can block blood flow at the point of clot formation or break free to block it elsewhere (embolism).
throne Chair of state set on a dais and often surmounted by a canopy, representing the power of the digni¬ tary who sits on it and sometimes conferring that power. In Greek his¬ tory, thrones were identified as seats of the gods; soon the meaning of the word included the symbolic seats of those who held religious or secular power, a meaning common to virtu¬ ally all cultures. The oldest surviving throne was built into the walls of Knossos (c. 1800 bc). Probably the most magnificent was the jewel- studded Peacock Throne of the rul¬ ers of Delhi, stolen from India by Persia in 1739 and thereafter the symbol of the Persian/Iranian mon¬ archy. In the late 17th and 18th cen¬ tury, thrones were often made of silver, but later versions tend to be of gilded wood.
throttle Valve for regulating the supply of a fluid (as steam) to an engine, especially the valve control¬ ling the volume of vaporized fuel delivered to the cylinders of an internal-combustion engine. In an automo¬ bile engine, gasoline is held in a chamber above the carburetor. Air flows down through the throat of the carburetor, past the throttle valve, and into the intake manifold. A throat is formed by the reduced diameter, and acceleration of the air through this smaller passage causes a decrease in pressure related to the amount of air flowing. This decrease in throat pres¬ sure results in fuel flow from the jet into the airstream. Any increase in airflow caused by change in engine speed or throttle position increases the pressure differential acting on the fuel and causes more fuel to flow. See also venturi tube.
thrush Any of about 300 species of songbirds (family Turdidae) that usu¬ ally have a slender bill and “booted” lower legs (i.e., covered in front with one long scale instead of many short ones). Thrushes are 5-12 in. (13-30 cm) long. Most have dull plumage, often with patches of bright yellow, red, or blue. They are found virtually worldwide but are most diverse in the Old World, especially in Africa. The northern species are strong migrants. Occupying a wide range of arboreal and terrestrial habitats, thrushes eat insects and fruit; a few eat snails or earthworms. They lay three to six eggs in an open cup-shaped nest; a few occupy cavities. Some of the thrushes,
So-called throne of King Dagobert I, bronze, from the treasury of Saint- Denis, Paris, probably 8th century with 12th-century additions
COURTESY OF THE BIBLIOTHEQUE NATIONALE, PARIS
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Thuan Thien ► thyme I 1905
including the hermit thrush and wood thrush, have notably beautiful songs. See also blackbird, bluebird, chat, ouzel, redstart, robin.
Thuan Thien See Le Loi
Thucydides Uhii-'si-do-.dezX (b. c. ancient Greek historians. An Athe¬ nian who commanded a fleet in the Peloponnesian War, Thucydides failed to prevent the capture of the important city of Amphipolis and consequently was exiled for 20 years. During that period he wrote his History of the Peloponnesian War. ; evidently he did not live to complete it, for it stops abruptly in 411 bc. It presents the first recorded political and moral analysis of a nation’s war policies, treating the causes of the conflict, the characters of the two states, and the technical aspects of warfare in a carefully drawn, strictly chronological narra¬ tive of events, including some in which he took an active part.