Teflon Trademark for a polymer of tetrafluoroethylene fluorocarbon (poly- tetrafluoroethylene [PTFEJ). Teflon is a tough, waxy, nonflammable organic compound with a slippery surface, attacked by very few chemi¬ cals and stable over a wide temperature range. Its qualities make it use¬ ful in gaskets, bearings, container and pipe linings, electrical insulation, parts for valves and pumps used for corrosive fluids, and protective non¬ stick coatings on cooking utensils, saw blades, and other articles. A closely related fluorocarbon polymer, fluorinated ethylene-propylene (FEP), has properties and applications similar to those of Teflon.
Tegea \'te-je-o\ Ancient city, eastern Arcadia, southern Greece. It was under Spartan rule from the mid-6th century bc until Thebes' victory over Sparta in the battle of Leuctra c. 371 bc. Afterward it joined a succession of leagues, and by the early 1st century ad was the only important town in Arcadia. It survived the Goth invasion in 395-396 and flourished under Byzantine and Frankish rule. It is the site of the Temple of Athena Alea, built by the city’s traditional founder, Aleus, and rebuilt in the 4th cen¬ tury bc by the sculptor Scopas.
Tegernsee \ , ta-gom- 1 za\ Lake, southern Bavaria, southeastern Germany. Located in the foothills of the Alps, it covers 3.5 sq mi (9 sq km). Sur¬ rounded by wooded mountains, it is a popular resort and recreation area. The castle of Maximilian I lies on the eastern shore.
Tegucigalpa \ta-,gu-se-'gal-pa\ City (pop., 2001: 769,061), capital of Honduras. Located on hilly terrain hemmed in by mountains, it was founded in 1578 as a gold- and silver-mining centre. It was made the per¬ manent capital of Honduras in 1880. It produces textiles and sugar. Prin¬ cipal buildings include the presidential and legislative palaces, the National University of Honduras (1847), and an 18th-century cathedral.
Tehran or Teheran \,ta-(9-)'ran\ City (pop., 1996: 6,758,845), capital of Iran. It is situated on the southern slopes of the Elburz Mountains. It was originally a suburb of ancient Rhagae (Rey), which was destroyed by the Mongols in 1220 and was later the home of several Safavid rulers of Persia (16th-18th centuries). It became prominent after its capture by Agha Muhammad Khan, founder of the Qajar dynasty, who made it his capital in 1785. It underwent rapid modernization after 1925 and espe¬ cially after World War II (1939-45). In 1943 it was the site of the Tehran Conference. In 1979, following the Islamic revolution in Iran, the U.S. embassy there was seized and its staff taken hostage by Iranian militants (see Iran hostage crisis). A transportation and industrial centre, Tehran produces more than half of Iran’s manufactured goods. It is the seat of several educational institutions, including the University of Tehran
(1934).
Tehran Conference (Nov. 28-Dec. 1, 1943) Meeting of Franklin Roosevelt, Winston Churchill, and Joseph Stalin in Tehran during World War II to discuss military strategy and political issues. Stalin agreed to launch a military offensive from the east to coincide with a planned inva¬ sion of German-occupied France from the west. Also discussed but not settled were eastern Europe’s postwar borders, including Poland’s post¬ war status, and a postwar international organization.
Tehuantepec \ta-'wan-ta-,pek\ A Gulf of Inlet of the Pacific Ocean, southeastern Mexico. It extends 300 mi (500 km) between Oaxaca and Chiapas states and is 100 mi (160 km) wide at its mouth. Numerous lagoons mark its shores, and the Tehuantepec River and numerous smaller streams flow into it. Its southern shore forms the Isthmus of Tehuantepec.
Teide \'ta-,tha\ A Pico de or Pico de Tenerife Vpe-ko-da-.tan-o-'ref-oV Volcanic peak on the island of Tenerife, Canary Islands. At 12,198 ft (3,718 m) tall, it is the highest point on Spanish soil. Vents within its cra¬ ter and on its slopes eject hot gases. The peak is atop a volcanic cone on
the upper reaches of El Teide, a conglomeration of several volcanoes; its last eruption was in 1789. It lies within a national park. Nearby is an international solar observatory.
Teilhard de Chardin N.ta-yar-do-shar-'daA, (Marie-Joseph-) Pierre (b. May 1, 1881, Sarcenat,
France—<1. April 10, 1955, New York, N.Y., U.S.) French philosopher and paleontologist. Ordained a Jesuit priest in 1911, he taught geology from 1918 at the Institut Catholique in Paris. In 1929 he directed the excavations at the Peking man site at Zhoukoudian. This and other geologi¬ cal work won him high honours, though it came to be disapproved of by the Jesuit order. His philosophy was strongly informed by his scien¬ tific work, which he believed helped prove the existence of God. He is known for his theory that mankind is evolving, mentally and socially, toward a final spiritual unity that he called the Omega point. Though his major philosophical works. The Divine Milieu (1957) and The Phe¬ nomenon of Man (1955), were written in the 1920s and ’30s, their pub¬ lication in his lifetime was forbidden by the Jesuits.
Tekakwitha \,tek-3-'kwith-3\ A Kateri (b. 1656, probably Ossernenon, New Netherland—d. April 17, 1680, Caughnawaga, Que.) First North American Indian considered for canonization. The daughter of an Algon¬ quin Christian mother and a non-Christian Mohawk father, she was born in what is now Auriesville, N.Y., U.S., and was partially blinded by small¬ pox as a child. She was deeply impressed by the lives and words of three Jesuit missionaries she met at age 11, and at 20 she was baptized. Harassed and threatened with torture in her home village, she fled 200 mi (320 km) to a Christian Indian mission near Montreal, where she became known as the “Lily of the Mohawks” for her kindness, faith, and heroic suffering before her early death. She was beatified in 1980.
tektite Any of a class of small, natural glassy objects found on the Earth’s surface and associated with meteorite impacts. The extremely high temperatures and enormous pressures generated when a large meteorite, comet, or asteroid hits the Earth melt the rocks at the site, producing masses of molten droplets that are blasted into and out of the Earth’s atmosphere. The droplets cool quickly to a glassy form and then fall back to the Earth.
Tel Aviv-Yafo Vel-o-'vev-'ya-foV or Tel Aviv-Jaffa
N.tel-o-'vev-'ja-foX City (pop., 1999 est.: 348,100) and main port of Israel. The hub of Israel’s largest urban centre, it was formed in 1950 by the incorporation of the ancient port of Jaffa with Tel Aviv, its former sub¬ urb. Tel Aviv was founded in 1909 and was the capital of Israel (1948- 50). It grew with Jewish immigration in the early 20th century and by 1936 was the largest and most important city in Palestine. Jaffa was an old Canaanite city that was taken by Egypt in the 15th century bc and occupied by the Israelite kings David and Solomon. Over the centuries it was ruled by the Ptolemies, Syrians, and Romans, captured by the Cru¬ saders, and razed by the Mamluks. The British occupied it in 1917; it surrendered to Jewish military forces during the first Arab-Israeli war (1948). Israel’s main business, communications, and cultural centre, it is the site of more than half of Israel’s industrial plants, the country’s stock exchange, Tel Aviv University (1953), and Bar-Ilan University (1953).
telecommunications Communication between parties at a distance from one another. Modem telecommunication systems—capable of trans¬ mitting telephone, fax, data, radio, or television signals—can transmit large volumes of information over long distances. Digital transmission is employed in order to achieve high reliability with minimal noise, or inter¬ ference, and because it can transmit any signal type, digital or analog. For digital transmission, analog signals must be subjected to a process of analog-to-digital conversion; most television, radio, and voice communi¬ cations are analog and must be digitized before transmission. Transmis¬ sion may occur over cables, wireless radio relay systems, or via satellite links.