periscope Optical instrument (see optics) used in land and sea warfare, submarine navigation, and elsewhere to enable an observer to see the sur¬ roundings while remaining under cover, behind armour, or submerged. A periscope includes two mirrors or reflecting prisms to change the direction of the light coming from the scene observed: the first deflects it down through a vertical tube, the second diverts it horizontally so that the scene can be viewed conveniently.
peristalsis \,per-9-'st6l-s9s\ Progressive wavelike muscle contractions in the esophagus, stomach, and intestines, and sometimes in the ureters and other hollow tubes. The waves can be short, local reflexes or long, con¬ tinuous contractions along the length of the organ. In the esophagus, peri¬ staltic waves push food into the stomach. In the stomach, they help mix stomach contents and propel food to the small intestine, where they expose food to the intestinal wall for absorption and move it forward. Peristalsis in the large intestine pushes waste toward the anal canal and is important in removing gas and dislodging potential bacterial colonies.
I peritonitis \,per-3-t 3 n-'i-t3s\ Inflammation of the peritoneum (see abdomi-
m nal cavity), with pus accumulating between the parietal and the visceral
peritoneum, abdominal pain and distension, vomiting, and fever. It may be acute or chronic, local or generalized. Acute peritonitis usually results m from inflammation elsewhere (e.g., by spread of bacterial infection). Pri¬ ll mary peritonitis often comes from a perforated gastrointestinal tract, as
with rupture in appendicitis. Control of the source problem may be fol¬ lowed by remission, adhesions, or abscesses (much rarer since the devel¬ opment of antibiotics).
periwinkle In botany, any of various plants of the genus Vinca of the dogbane family. The lesser periwinkle (U minor), which has small lilac- blue flowers, is a dependable, trailing, evergreen perennial that is native to Europe and has become widespread over much of eastern North America. The greater periwinkle (U major), with larger leaves and larger purplish-blue flowers, is native to continental Europe and has become naturalized in England. Alkaloids derived from the periwinkle plant have had some success in inhibiting cancer growth.
periwinkle In zoology, any of some 80 species (family Littorinidae) of widely distributed, chiefly herbivorous shore SNAILS. Periwinkles are usu¬ ally found on rocks, stones, or pilings between high- and low-tide marks. The common periwinkle ( Littorina littorea), the largest northern species, may grow to 1.5 in. (4 cm) long. It is usually dark gray and has a solid spiral shell. Introduced into North America c. 1857, it is now common on Atlantic coasts. All periwinkle species are a favourite food of many shore- birds. See photograph above.
Periyar \,per-i-'yar\ River River, central Kerala state, southwestern India. It is 140 mi (225 km) long and rises in the Western Ghats range near the border with Tamil Nadu state. It flows north to Periyar Lake, an arti¬ ficial reservoir created by damming the river. A tunnel carries water from the lake eastward through the moun¬ tains to the Vaigai River, where it is used for irrigation. From the lake it flows northwest and empties into the Arabian Sea.
perjury In law, act or crime of knowingly making a false statement while under oath. The statement must be material to the issue of inquiry. Perjuries that have the effect of obstructing the adjudication of a case may be given increased punishment for that reason. A person who makes a false statement and later corrects it is usually not considered to have committed perjury.
Perkins, Anthony (b. April 4, 1932, New York, N.Y., U.S.—d. Sept. 12, 1992, Hollywood, Calif.) U.S. film actor. He was the son of the actor Osgood Perkins, and he studied at Columbia University. After making his screen debut in The Actress (1953), he appeared in films such as Friendly Persuasion (1956) and Fear Strikes Out (1957), but he was best known as the murderous motel owner Norman Bates in Alfred Hitchcock’s Psy¬ cho (1960). He later appeared in several films in Europe, including The Trial (1963), The Champagne Murders (1967), and Ten Days’ Wonder (1972), and in U.S. films such as Pretty Poison (1968), Catch-22 (1970), and WUSA (1970). He reprised his role as Norman Bates in three sequels (1983, 1986, and 1990).
Perkins, Frances orig. Fannie Coralie Perkins (b. April 10, 1882, Boston, Mass., U.S.—d. May 14,1965, New York, N.Y.) U.S. public official. She became a social worker in New York City and a leader in orga¬ nizations aiming to improve working conditions for women. From 1929 to 1933 she served as state industrial commissioner under New York Gov. Franklin D. Roosevelt. As president, Roosevelt appointed her U.S. secretary of labor; she thereby became the first woman to hold a U.S. cabinet post. In her long term of office (1933—45) she advocated reforms such as a minimum wage, a maximum workweek, and unemployment compensation; she also helped draft the Social Security Act and supervised the Fair Labor Standards Act (1938). She was later a U.S. Civil Service commissioner (1945-53).
Perkins, Jacob (b. July 9, 1766, Newburyport, Mass., U.S.—d. July 30, 1849, London, Eng.) U.S. inventor. He built a machine to cut and head nails in one operation c. 1790. He developed a method of engraving paper money that made counterfeiting difficult; lack of interest in the U.S. led him to set up a bank-note factory in England (1819). He experimented with high-pressure steam boilers, built a horizontal steam engine (1827), designed an improved paddle wheel (1829), and invented a means for the free circulation of water in boilers (1831) that led to the design of mod¬ ern water-tube boilers.
Perkins, Maxwell (Evarts) (b. Sept. 20, 1884, New York, N.Y., U.S.—d. June 17, 1947, Stamford, Conn.) U.S. editor. He worked as a reporter for The New York Times before joining the publishing firm of Charles Scribner’s Sons, of which he later became editorial director and vice president. He is best known for the intensive editorial work that shaped Thomas Wolfe’s sprawling manuscripts into publishable form, but he also assisted the early careers of F. Scott Fitzgerald, Ernest Hemingway, Ring Lardner, Erskine Caldwell, Edmund Wilson, and Alan Paton.
Perl in full Practical Extraction and Reporting Language.
High-level computer programming language, the most popular language for writing CGI scripts and the premier scripting (or interpreted) language of the World Wide Web. Since it has roots in UNIX, its syntax is similar to C and it includes several UNIX utilities. Because of its excellent text¬ processing capability, it is widely used by system administrators (for writ¬ ing administrative tasks) and is especially suited for developing prototype versions of programs. Because it is an interpreted language, its programs are highly portable across different operating systems. Originally devel¬ oped by Larry Wall at NASA’s Jet Propulsion Laboratory in 1986, it has since been improved by hundreds of volunteer developers. Like Linux, it can be obtained free of charge.
Periwinkles ( Littorina)
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perlite ► Perpignan I 1475
perlite or pearlstone Natural glass with concentric cracks such that the rock breaks into small, pearl-like bodies. It is formed by the rapid cooling of viscous lava or magma. Perlite is porous and has a waxy to pearly lustre and is commonly gray or greenish but may be brown, blue, or red. Since c. 1950, large deposits have been worked in New Mexico, Nevada, California, and other western states. Heat-treated perlite is a sub¬ stitute for sand in lightweight wall plaster and concrete aggregate. Perlite is used for heat and sound insulation, lightweight ceramic products, and filters.
Perlman, Itzhak (b. Aug. 31, 1945, Tel Aviv, Palestine) Israeli-born U.S. violinist. Despite a bout with polio at age four that left his legs para¬ lyzed, he was a prodigy, and he made his U.S. television debut at age 13. He studied with Ivan Galamian and Dorothy DeLay at Juilliard. Recog¬ nition of his gifts led to a highly successful career as orchestral soloist and chamber-music player, with scores of recordings. Blessed with a popular touch, he appeared on television, played jazz and klezmer music, and involved himself in educating young musicians.