prescriptivism In metaethics, the view that moral judgments are pre¬ scriptions and therefore have the logical form of imperatives. Prescrip¬ tivism was first advocated by Richard M. Hare (born 1919) in The Language of Morals (1952). Hare argued that it is impossible to derive any prescription from a set of descriptive sentences, but tried neverthe¬ less to provide a foothold for moral reasoning in the constraint that moral judgments must be “universalizable”: that is, that if one judges a particu¬ lar action to be wrong, one must also judge any relevantly similar action to be wrong. Universalizability is not a substantive moral principle but a logical feature of the moral terms: anyone who uses such terms as “right” and “ought” is logically committed to universalizability.
preservation, food See food preservation
preservative Any of numerous chemical additives used to prevent or slow food spoilage caused by chemical changes (e.g., oxidation, mold growth) and maintain a fresh appearance and consistency. Antimycotics (e.g., sodium and calcium propionate, sorbic acid) inhibit mold growth;
antioxidants (e.g., butylated hydroxytoluene or BHT) delay rancidity in foods containing fats and oils; antibiotics (e.g., tetracyclines) prevent bac¬ terial growth; humectants retain moisture in products like shredded coco¬ nut; and antistaling agents (e.g., glyceryl monostearate) maintain moisture and softness in baked goods. Some preservatives also improve the appear¬ ance of the product (e.g., sodium nitrate and nitrite in meats).
president In government, the officer who serves as head of state and sometimes also as chief executive. In countries where the president is chief of state but not of government, the role is largely ceremonial, with few or no political powers. Presidents may be elected directly or indi¬ rectly, for a limited or unlimited number of terms. In the U.S., the presi¬ dent’s chief duty is to ensure that the laws are faithfully executed, which he does through various executive agencies and with the aid of his cabi¬ net. He also serves as commander in chief of the armed forces, nominates judges to the Supreme Court, and makes treaties with foreign governments (contingent on Senate approval). The office of president is used in gov¬ ernments in South and Central America, Africa, and elsewhere. In west¬ ern Europe executive power is generally vested in a prime minister and his cabinet, and the president, where the office exists, has few responsibili¬ ties (though France is a significant exception).
Presley, Elvis (Aaron) (b. Jan. 8, 1935, Tupelo, Miss., U.S.—d. Aug. 16, 1977, Memphis, Tenn.) U.S. popular singer, the “King of Rock and Roll.” Presley was raised in Memphis, where he sang Pentecostal church music and listened to black bluesmen and Grand Ole Opry broadcasts. In 1954 he began to record for the producer Sam Phillips, who had been searching for a white singer who sounded like a black man. In 1956, under his new manager, “Colonel” Tom Parker, he released “Heartbreak Hotel,” the first of numerous million-selling hits that included “Hound Dog” and “All Shook Up.” In the same year, he appeared in Love Me Tender , the first of 33 mediocre films, and on several TV shows, notably the Ed Sul¬ livan Show. Presley’s intensely charismatic style—including his sexy hip shaking, ducktail haircut, and characteristic sneer—excited young fans, especially females, to wild adulation. After a stint in the army (1958-60) he resumed recording and acting, but his earlier raucous style was mod¬ erated. In 1968 he introduced a Las Vegas-based touring act with orches¬ tra and gospel-type choir. Battling public pressures, weight gain, and drug dependence, he underwent a personal decline. His death at age 42, attrib¬ uted to natural causes, was mourned by hundreds of thousands of fans at Graceland, his Memphis estate, which remains a place of international pilgrimage.
Prespa, Lake Lake on the boundary between Macedonia, Albania, and Greece. It is 14 mi (23 km) long, 8 mi (13 km) wide, 2,800 ft (853 m) above sea level, and it drains northwest into Lake Ohrid through a sub¬ terranean channel. South of it is Little Prespa Lake, which contains the island of St. Achilius; the island was an early capital of Bulgarian Tsar Samuel in the 10th century. It became a tourist and fishing centre in the 1970s.
Pressburg See Bratislava
Pressburg, Treaty of (Dec. 26, 1805) Agreement signed by Austria and France at Pressburg (now Bratislava, Slvk.) after Napoleon’s victo¬ ries at the Battles of Ulm and Austerutz. Austria gave up Venetia to Napo¬ leon’s kingdom of Italy and the Tirol and Vorarlberg to Bavaria. Austria agreed to admit the electors of Bavaria and Wurttemberg, allied with Napoleon, to the rank of kings, which further reduced Austrian influence in Germany. Austria’s influence was also excluded from Italy. The treaty enabled Napoleon to create a ring of French client states beyond France.
pressure Perpendicular force per unit area, or stress at a point within a confined fluid. A solid object exerts pressure on a floor equal to its weight divided by the area of contact. The weight of the Earth’s atmosphere on the surface constitutes atmospheric pressure, which varies from place to place but always decreases with altitude. The pressure exerted by a con¬ fined gas results from the average effect of the forces produced on the walls of the container by the continual, numerous collisions by gas mol¬ ecules. Hydrostatic pressure is the stress, or pressure, exerted equally in all directions at points within a confined fluid. Lithostatic pressure is the stress exerted on a body of rock in the Earth’s crust by surrounding rock, which increases with depth below the surface. The SI unit of pressure is the pascal (Pa), which is equal to one newton of force per square metre.
pressure gauge Instrument for measuring the condition of a fluid (liquid or gas) that is specified by the force the fluid would apply, when
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PresterJohn ► price I 1545
at rest, to a unit area, such as pounds per square inch (psi) or pascals (Pa). The reading on the gauge, called the gauge pressure, is always the dif¬ ference between two pressures. When the lower of the pressures is that of the atmosphere, the total (or absolute) pressure is the sum of the gauge and atmospheric pressures.
Prester John Legendary Christian ruler of the East. He was believed to be a Nestorian and a king-priest (prester being short for presbyter, “elder” or “priest”) reigning in an unspecified part of the Far East. The legend arose during the Crusades in the 12th century, among European Christians who hoped that Prester John would prove an ally in the effort to regain the Holy Land from the Saracens. In the 13th—14th century vari¬ ous missionaries and travelers, including Marco Polo, searched for his kingdom in Asia. After the mid-14th century, Ethiopia was the centre of the quest, as Prester John became identified with the emperor of that Afri¬ can Christian nation.
Prestes \'pras-tas\, Luis Carlos (b. Jan. 3, 1898, Porto Alegre, Rio Grande do Sul, Braz.—d. March 7, 1990, Rio de Janeiro) Brazilian revo¬ lutionary. Beginning in 1924, he led a rebel force on a three-year trek through Brazil’s interior in an effort to spark a rebellion in the country¬ side. Although the effort failed, he became a romantic hero. He went on to lead the Brazilian Communist Party, which advocated ending payments on the national debt, nationalization of foreign-owned companies, and land reform. Imprisoned after a violent uprising in 1935, he was released after World War II and later served briefly as a senator.
Preston City and borough (pop., 2001: 129,642), county seat of Lan¬ cashire, England. On the River Ribble, Preston grew near the site of a Roman fort and received its first charter in 1179. As a market centre, it became known for its wool and linen weaving and its cotton mills. It was the site of the Lancashire Royalist headquarters during the English Civil Wars. The Royalists were defeated there by Oliver Cromwell in 1648. Despite the decline of the cotton textile industry, the economy has remained strong through diversification, and it produces aircraft and motor vehicles.