tear duct and gland or lachrymal Ylak-re-msH duct and gland Structures that produce, distribute, and carry away tears. An almond-shaped gland above the outer comer of each eye secretes tears between the upper eyelid and the eyeball. Tears moisten and lubricate the conjunctiva (the membrane that lines the eyelid and covers the white of the eye) and then flow into the barely visible openings (near the inner comers of the eyelids) of the tear ducts, which lead to the nasal cavity. Oil (from sebaceous glands on the edge of the eyelid) keeps tears from spilling out unless secretion increases because of crying or a reflex trig¬ gered by stimuli such as eye irritation, bright lights, or spicy foods.
tear gas Any of a group of substances, most often synthetic organic halogen compounds, that irritate the mucous membranes of the eyes, caus¬ ing a stinging sensation and tears. They may also irritate the upper res¬ piratory tract, causing coughing, choking, and general debility. Tear gas was first used in warfare in World War I, but since its effects are short- lasting and rarely disabling, it came into use by law-enforcement agen¬ cies as a means of dispersing mobs, disabling rioters, and flushing out armed suspects without the use of deadly force.
Teasdale, Sara orig. Sara Trevor Teasdale (b. Aug. 8, 1884, St. Louis, Mo., U.S.—d. Jan. 29, 1933, New York, N.Y.) U.S. poet. While living in St. Louis she made frequent trips to Chicago, where she even¬ tually joined Harriet Monroe’s Poetry magazine circle. Her collection Riv¬ ers to the Sea (1915) established her as a popular poet, and Love Songs (1917) won the first Pulitzer Prize for poetry. Over time her verse became simpler and more austere. After her marriage ended in divorce in 1929, she moved to New York City, where she lived in virtual retirement. Many of the poems in her last book, Strange Victory (1933), foreshadow her suicide.
teasel Vte-zoL Any of about 15 species constituting the genus Dipsa- cus of the family Dipsacaceae (the teasel family), native to Europe, the Mediterranean area, and tropical Africa. Many teasels are prickly, coarse biennials with tall-domed heads of numerous, four-lobed flowers that sit on a crownlike circle of spiny, narrow bracts. The spiny, dry fruiting heads of fuller’s teasel ( D. sativus ) have been used since Roman times to raise the nap of woolen fabrics in a process known as fulling.
Tebaldi Xta-'bal-deX, Renata (b. Feb. 1, 1922, Pesaro, Italy—d. Dec. 19, 2004, San Marino) Italian soprano. After her debut in Mefistofele in 1944, she established herself at La Scala, performing with the conductor Arturo Toscanini for the 1946 reopening concert and over the next decade. Her debuts at Covent Garden (1950) and the Metropolitan Opera (1955) were both in the role of Desdemona, and she sang at the Met for 17 years in roles such as Tosca, Manon Lescaut, Mimi, and Violetta. She retired in 1976.
technetium \tek-'ne-she-3m\ Metallic chemical element, one of the tran¬ sition elements, chemical symbol Tc, atomic number 43. All its isotopes are radioactive (see radioactivity); some occur in trace amounts in nature as nuclear fission products of uranium. Its isotope technetium-97 was the first element artificially produced (1937; see cyclotron). Technetium-99, a fis¬ sion product of nuclear reactors that emits gamma rays, is the most-used tracer isotope in nuclear medicine. Technetium resembles platinum in appearance and manganese and rhenium in chemical behaviour. It is also used as a metallurgical tracer and in corrosion-resistant products.
technical education Academic and vocational preparation of students for jobs involving applied science and modern technology. It emphasizes the understanding and practical application of basic principles of science and mathematics, rather than the attainment of proficiency in manual skills that is properly the concern of vocational education. The goal of techni¬ cal education is to prepare graduates for occupations that are classified above the skilled crafts but below the scientific or engineering profes¬ sions. People so employed are frequently called technicians. See also employee training.
techno Electronic dance music that first appeared in the U.S. in the 1980s and became globally popular in the 1990s. It originated with Detroit deejay-producers who, inspired by European electro-pop, underlaid dreamy synthesizer melodies with rapid electronic rhythms. Imported in Europe, it was adopted by the burgeoning rave scene of all-night dance parties (which often featured the hallucinogen ecstasy) and is celebrated in the annual Love Parade in Berlin.
technology Application of knowledge to the practical aims of human life or to changing and manipulating the human environment. Technology includes the use of materials, tools, techniques, and sources of power to make life easier or more pleasant and work more productive. Whereas science is concerned with how and why things happen, technology focuses on making things happen. Technology began to influence human endeav¬ our as soon as people began using tools. It accelerated with the Industrial Revolution and the substitution of machines for animal and human labour. Accelerated technological development has also had costs, in terms of air and water pollution and other undesirable environmental effects.
tectonics Scientific study of the deformation of the rocks that make up the Earth’s crust and the forces that produce such deformation. It deals with the folding and faulting associated with mountain building; the large- scale, gradual, upward and downward movements of the crust; and sud¬ den horizontal displacements along faults. Other phenomena studied include igneous processes and metamorphism. The chief working prin¬ ciple of tectonics is the concept of plate tectonics. See also continental drift; seafloor spreading.
tectonism See diastrophism
Tecumseh Vto-'kom-soN (b. 1768, Old Piqua, in modern Clark county, Ohio, U.S.—d. Oct. 5, 1813, near Thames River, Upper Canada) Shaw¬ nee Indian chief. As a boy during the American Revolution, Tecumseh participated in combined British and Indian attacks on American colo¬ nists. In 1794 he fought unsuccessfully against Gen. Anthony Wayne. He eventually established a confederation made up of members of the Creek and other nations. In 1811 his brother’s attack on William H. Harrison’s troops at Tippecanoe, Ind., ended in defeat. As the War of 1812 approached, Tecumseh assembled his followers under the British banner and captured Detroit. Several lesser successes followed, ending with his death at the Thames River in what is now Ontario, marking the end of Indian resis¬ tance in the Old Northwest (as the East North Central states were some¬ times known).
Tedder (of Glenguin), Arthur William Tedder, 1 st Baron (b.
July 11, 1890, Glenguin, Stirling, Scot.—d. June 3, 1967, Banstead, Sur¬ rey, Eng.) British air marshal. He joined the British army in 1913, trans¬ ferred to the Royal Flying Corps in 1916, and after World War I commanded a branch of the Royal Air Force (RAF). As head of the RAF
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1882 I Tees River ► telecommunications
Middle East Command in World War II, he commanded Allied air opera¬ tions in North Africa and Italy, and in 1944 he was appointed head of Allied air operations in western Europe. His policy of bombing German communications and providing close air support of ground operations contributed significantly to the success of the Normandy Campaign and the Allied advance into Germany. He later became the first peacetime chief of the air staff (1946-50).
Tees River \'tez\ River, northern England. It rises in the northern Pen- nines and flows 70 mi (110 km) east to the North Sea. There are falls and reservoirs along its course. Teesside, the urban area at the river’s mouth, has seen large-scale industrial development since the railroad arrived in