servitude In property law, a right by which property owned by one per¬ son is subject to a specified use or enjoyment by another. Servitudes allow people to create stable long-term arrangements for a wide variety of pur¬ poses, including shared land uses; maintaining the character of a residen¬ tial neighbourhood, commercial development, or historic property; and financing infrastructure and common facilities. Modem European civil law is derived from Roman law, which divides real servitudes into rural (those owed by one estate to another) and urban (those established for conve¬ nience). Rural servitudes include various rights of way; urban servitudes include building rights in neighbouring properties, such as drainage and encroachment rights, and rights to light, support, and view. See also ease¬ ment.
servomechanism Device used to correct the performance of a mecha¬ nism automatically, by means of error-sensing feedback. The term prop¬ erly applies only to systems in which the feedback and error-correction signals control mechanical position or velocity. Servomechanisms were first used in military and marine navigation equipment. Today they are used in automatic machine tools, satellite-tracking antennas, celestial¬ tracking systems on telescopes, automatic navigation systems, and antiaircraft-gun control systems. The design of servomechanisms is con¬ sidered to be a branch of both robotics and cybernetics.
sesame Erect, annual plant ( Sesamum indicum ) of numerous types and varieties in the family Pedaliaceae. It has been cultivated since antiquity for its seeds, which are used as food and flavouring and yield a prized oil. The hulled seeds, creamy or pearly white and tiny, have a mild, nutlike aroma and taste. The whole seed is used extensively in the cuisines of the Middle East and Asia. Sesame oil, noted for its stability and its resistance to becoming rancid, is used as a salad or cooking oil, in shortening and margarine, in the manufacture of soaps, pharmaceuticals, and lubricants, and as an ingredient in cosmetics.
Sessions, Roger (Huntington) (b. Dec. 28, 1896, Brooklyn, N.Y., U.S.—d. March 16, 1985, Princeton, N.J.) U.S. composer. He attended Harvard and Yale, lived in Italy and Germany (1925-33), and later taught principally at Princeton University (1935—45, 1953-65). His early inter¬ est in Neoclassicism was replaced c. 1953 by his adoption of serialism. His works include the operas The Trial of Lucullus (1947) and Montezuma (1963), incidental music to The Black Maskers (1923), eight symphonies, a Concerto for Orchestra (1982, Pulitzer Prize), and the cantata When Lilacs Last in the Door-yard Bloom’d (1970), as well as several widely read books on music.
set In mathematics and logic, any collection of objects (elements), which may be mathematical (e.g., numbers, functions) or not. The intuitive idea
of a set is probably even older than that of number. Members of a herd of animals, for example, could be matched with stones in a sack without members of either set actually being counted. The notion extends into the infinite. For example, the set of integers from 1 to 100 is finite, whereas the set of all integers is infinite. A set is commonly represented as a list of all its members enclosed in braces. A set with no members is called an empty, or null, set, and is denoted 0. Because an infinite set cannot be listed, it is usually represented by a formula that generates its elements when applied to the elements of the set of counting numbers. Thus, {2x | x = 1,2,3,...} represents the set of positive even numbers (the vertical bar means “such that”).
set theory Branch of mathematics that deals with the properties of sets. It is most valuable as applied to other areas of mathematics, which bor¬ row from and adapt its terminology and concepts. These include the opera¬ tions of union (u), and intersection (n). The union of two sets is a set containing all the elements of both sets, each listed once. The intersec¬ tion is the set of all elements common to both original sets. Set theory is useful in analyzing difficult concepts in mathematics and logic. It was placed on a firm theoretical footing by Georg Cantor, who discovered the value of clearly formulated sets in the analysis of problems in symbolic logic and number theory.
setback In architecture, a steplike recession in the profile of a high-rise building. Usually dictated by building codes to allow sunlight to reach streets and lower floors, the building must take another step back from the street for every specified added height interval. Without building set¬ backs, many of New York City’s streets would be in constant shadow. In the 1920s architects drew attention to their setbacks with decorative devices—mosaics; Chinese, Mayan, or Greek motifs; or geometric blocks—but later architects deemphasized them. The International Style glass-wall skyscraper was typically built without intermittent setbacks, but architects met zoning requirements by creating one huge setback at ground level that created a plaza. The late 20th century saw a return to decorative setbacks.
Seth or Set Ancient Egyptian god and patron of the 11th nome, or prov¬ ince, of Upper Egypt. A trickster, he was a sky god, lord of the desert, and master of storms, disorder, and warfare. He was the brother of Osiris, whom he killed, and he was antagonistic to Horus, the child of Osiris’s sister, Isis. Seth’s cult largely died out in the 1st millennium bc, and he was gradually ousted from the Egyptian pantheon. He was later regarded as entirely evil and identified as a god of the Persians and other invaders of Egypt.
SETI in full search for extraterrestrial intelligence Ongoing effort to seek intelligent extraterrestrial life. SETI focuses on receiving and analyzing signals from space, particularly in the radio and visible- light regions of the electromagnetic spectrum, looking for nonrandom pat¬ terns likely to have been sent either deliberately or inadvertently by technologically advanced beings. The first modem SETI search was Project Ozma (I960), which made use of a radio telescope in Green Bank, W.Va. SETI approaches include targeted searches, which typically con¬ centrate on groups of nearby sunlike stars, and systematic surveys cov¬ ering all directions. The value of SETI efforts has been controversial; programs initiated by NASA in the 1970s were terminated by congres¬ sional action in 1993. Subsequently, SETI researchers organized privately funded programs—e.g., the targeted-search Project Phoenix in the U.S. and the survey-type SERENDIP projects in the U.S. and Australia. See also Drake equation.
Seti I (d. 1279 bc) Egyptian king of the 19th dynasty (r. 1290-79 bc). His father, Ramses I, had reigned only two years, and it was Seti who was the real founder of the greatness of the Ramessids. Seti did much to pro¬ mote Egypt’s prosperity. He fortified the frontier, opened mines and quar¬ ries, dug wells, and rebuilt temples and shrines; he continued work on the great hall at Karnak and built a temple at Abydos decorated with reliefs of great delicacy.
Seton \se-t°n. Saint Elizabeth Ann orig. Elizabeth Ann Bay-
ley known as Mother Seton (b. Aug. 28, 1774, New York, N.Y.—d. Jan. 4, 1821, Emmitsburg, Md., U.S.; canonized Sept. 14, 1975; feast day January 4) U.S. religious leader and educator, the first native-born U.S. citizen canonized by the Roman Catholic church. Bom into an upper-class family, she married William Magee Seton in 1794. In 1797 she founded the Society for the Relief of Poor Widows with Small Children, and in 1803 she was herself left a widow with five children. After converting
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1726 I Seton ► Seven Weeks'War
from Episcopalianism to Roman Catholicism in 1805, she opened a free Catholic elementary school in Baltimore, Md., in 1809. In 1813 she founded the Sisters of Charity, the first U.S. religious order, and she served as its superior until her death. She is often considered the mother of the parochial school system in the U.S.