Optimates and Populares \,ap-ti- , ma-tez... 1 pap-y9- , lar-ez\ Ideo¬ logical positions in ancient Rome that became defined in the early 1st century bc. Both groups came from the wealthier classes. The Optimates (Latin: “Best Ones,” “Aristocrats”) promoted the dominance of the Sen¬ ate and the proper balance of the constitution. The Populares (“Dema¬ gogues,” “Populists”) used and defended the powers of the popular assemblies and the office of tribune and advocated such measures as land distribution, debt cancellation, and subsidized grain allowances. Their polarization led to civil wars—notably those between Julius Caesar and Pompey and between Octavian (Augustus) and Mark Antony —and the fall of the republic with Augustus’s accession.
optimization Field of applied mathematics whose principles and meth¬ ods are used to solve quantitative problems in disciplines including phys¬ ics, biology, engineering, and economics. Questions of maximizing or minimizing functions arising in the various disciplines can be solved using the same mathematical tools (see maximum; minimum). In a typical optimi¬ zation problem, the goal is to find the values of controllable factors deter¬ mining the behaviour of a system (e.g., a physical production process, an investment scheme) that maximize productivity or minimize waste. The simplest problems involve functions (systems) of a single variable (input factor) and may be solved with differential calculus. Linear programming was developed to solve optimization problems involving two or more input variables. See also simplex method.
optometry \ap-'ta-ni3-tre\ Profession concerned with examining the eyes for defects or faults of refraction. Optometrists prescribe optical aids (e.g., eyeglasses, contact lenses), supervise eye exercise programs to treat vision problems, and examine the eyes for disorders such as glaucoma and cataracts. They are generally not licensed to prescribe drugs or trained to perform surgery. See also ophthalmology.
opuntia \o-'p3n-sh3\ Any plant of the genus Opuntia, the largest genus of the cactus family. Native to the New World, it has characteristic small bristles with backward-facing barbs. Subgroups are based on the form of the stem segments: chollas have cylindrical joints, while prickly pears have flat joints. Sizes range from tiny, cold-hardy forms to treelike varieties. In the Northern Hemisphere, opuntia is found farther north than any other cactus.
Virginia, or common, opossum (Didel¬ phis virginiana).
ROBERT J. ELUSON-THE NATIONAL AUDUBON SOCIETY COLLECTION/PHOTO RESEARCHERS
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Opus Dei ► Orbison I 1413
Opus Dei Latin "work of God" Roman Catholic lay and clerical organization whose actions and beliefs have been both criticized and praised. Its members seek personal Christian perfection, strive to imple¬ ment Christian ideals in their chosen occupations, and promote Christian values to society as a whole. Opus Dei, in full Prelature of the Holy Cross and Opus Dei, was founded in 1928 in Spain by Josemarfa Escriva de Balaguer y Alba (canonzied in 2002). It is theologically conservative and accepts the teaching authority of the church without question. It was granted special status as the first and only personal prelature in the church by Pope John Paul II in 1982 and has established numerous vocational schools and universities. It is also highly controversial, accused of secrecy, using cult-like recruiting practices, and having grand political ambitions. There are separate organizations for men and women, which, since 1982, have been headed by a prelate elected by its members. At the beginning of the 21st century priests constituted only a tiny percentage of the orga¬ nization, numbering roughly 1,600 of the nearly 84,000 members living in 80 countries.
oracle Source of a divine communication delivered in response to a petitioner’s request. Ancient Greece and Rome had many oracles. The most famous was that of Apollo at Delphi, where the medium was a woman over 50 called the Pythia. After bathing in the Castalian spring, she appar¬ ently would descend into a basement cell, mount a sacred tripod, and chew the leaves of the laurel, sacred to Apollo. Her utterances, which were often highly ambiguous, were interpreted by priests. Other oracles, including those at Claros (Apollo), Amphicleia (Dionysus), Olympia (Zeus), and Epi- daurus (Asclepius), were consulted through various other methods; for example, the oldest of the oracles, that of Zeus at Dodona, spoke through the whispering of the leaves of a sacred oak. At some shrines, the inquirer would sleep in the holy precinct and receive an answer in a dream.
oral tradition Cultural information passed on from one generation to the next by storytellers. The forms of oral tradition include poetry (often chanted or sung), folktales, and proverbs as well as magical spells, reli¬ gious instruction, and recollections of the past. Music and rhyme com¬ monly serve as both entertainment and aids to memory. Epic poems concerning the destiny of a society or summarizing its myths often begin as oral tradition and are later written down. In oral cultures, oral tradi¬ tion is the only means of communicating knowledge. The prevalence of radio, television, and newspapers in Western culture has led to the decline of oral tradition, though it survives among old people and some minority groups as well as among children, whose games, counting rhymes, and songs are transmitted orally from generation to generation.
Oran \o-'ran\City (pop., 1998: 692,516), northwestern Algeria. Situated on the Mediterranean Sea, it is about midway between Tangier, Morocco, and Algiers. With the adjacent Mers el-Kebir, it is the country’s second largest port. Founded in the 10th century by Andalusians as a base for trade with the northern African hinterland, it was held by the Spanish until 1708, when it fell to the Ottomans. It was devastated by an earthquake in 1790. In 1792 the Ottomans settled a Jewish community there. In 1831 it was occupied by the French, who established a modem port and naval base. In World War II (1939—45) it came under the control of the Allied Powers. Most of its European inhabitants left after Algerian independence in 1962. It is divided into a waterfront and the old and new city sections built on terraces above it.
orange Any of several species of small trees or shrubs in the genus Citrus of the rue (or citrus) family and their fruits. Grown in tropical and subtropical regions, the nearly round fruits have leathery, oily rinds and edible, juicy inner flesh rich in vitamin C. Key commercial species include the China (sweet, or common) orange; the mandarin orange (including tangerines); and seedless navel oranges. The tree has broad, glossy, medium-size evergreen leaves, leafstalks with narrow wings, and very fragrant flowers. It bears fruit abundantly for 50-80 years. Oranges do not improve in quality off the tree, so they are picked when fully ripe. A sizeable portion of the U.S. crop is processed for frozen concentrated juice. By-products include essential oils, pectin, candied peel, orange mar¬ malade, and stock feed.
Orange, house of Princely dynasty and royal family of The Nether¬ lands. The title began with William I (the Silent), prince of Orange-Nassau, who was stadtholder (viceroy) of the Netherlands, as were his descen¬ dants until 1795. In 1815 William VI became William I, king of The Neth¬ erlands. Through his descendants, the male line of the royal dynasty