fermion Any of a group of subatomic particles having odd half-integral spin (Vi, %). Fermions are named for the Fermi-Dirac statistics that describe
their behaviour. They include particles in the class of leptons, baryons, and nuclei of odd mass number (e.g., tritium, helium-3, uranium-233). They obey the Pauli exclusion principle. Fermions are produced and undergo annihilation in particle-antiparticle pairs. See also boson.
fern Any of about 10,000-12,000 species (division Filicophyta) of non¬ flowering vascular plants that have true roots, stems, and complex leaves and reproduce by spores. Though ferns were once classified with the primi-
The life cycle of the fern. (1) Clusters (sori) of sporangia (spore cases) grow on the undersurface of mature fern leaves. (2) Released from its spore case, the haploid spore is carried to the ground, where it germinates into a tiny, usually heart- shaped, gametophyte (gamete-producing structure), anchored to the ground by rhizoids (rootlike projections). (3) Under moist conditions, mature sperm are released from the antheridia and swim to the egg-producing archegonia that have formed on the gametophyte's lower surface. (4) When fertilization occurs, a zygote forms and develops into an embryo within the archegonium. (5) The embryo even¬ tually grows larger than the gametophyte and becomes a sporophyte.
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tive horsetails and club mosses, botanists have since made a clear distinc¬ tion between the scalelike, one-veined leaves of those plants and the more complexly veined fronds of the ferns, which are more closely related to the leaves of seed plants. Ferns come in a wide variety of sizes and shapes.
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668 i Fernando Poo ► Fessenden
Many are small, fragile plants; others are treelike (see tree fern). The life cycle is characterized by an alternation of generations between the mature, fronded form (the sporophyte) familial’ in greenhouses and gardens and the form that strongly resembles a moss or liverwort (the gametophyte). Ferns are popular houseplants.
Fernando Poo See Bioko
Ferrara \fer-'ra-ra\ City (pop., 2001 prelim.: 130,461), northern Italy. Situated near the Po River, it is probably the site of the ancient Forum Alieni. Ferrara first appears in historical records in ad 753, when it was captured from Ravenna by the Lombards. It became a cultural centre and the seat of a principality, but it declined after its incorporation into the Papal States in 1598. The site of an Austrian garrison from 1832, Ferrara became part of the Kingdom of Italy in 1861. It was severely damaged in World War II. Sites of interest include a 12th-century cathedral, a 14th- century moated castle, and the University of Ferrara (founded 1391).
Ferrara-Florence, Council of (1438-45) Ecumenical council held in an attempt to reunify the Eastern Orthodox and Roman Catholic churches. It was called by Pope Eugenius IV; the Eastern church was rep¬ resented by Emperor John VIII Palaeologus and others. Fear of facing the Turks without Western support led the Eastern participants to sign the Decree of Union (1439), but on their return to Constantinople most renounced it. Union was officially declared in Hagia Sophia in 1452, but the following year the Ottoman Empire captured Constantinople, and the few partisans of the union fled. In 1448 a council of Eastern bishops con¬ demned it officially. General support for the council and its goals strength¬ ened the authority of the papacy and contributed to the failure of the CONCILIAR MOVEMENT.
Ferraro, Geraldine (Anne) (b. Aug. 26, 1935, Newburgh, N.Y., U.S.) U.S. politician. She received her law degree from Fordham Univer¬ sity Law School in 1960 and was admitted to the New York bar in 1961. She practiced law in New York until 1974, when she became assistant U.S. district attorney. In 1978 she was elected to the U.S. House of Represen¬ tatives as a Democrat. In 1984 the Democratic Party nominated her for vice president on a ticket with Walter Mondale; she thereby became the first woman to be nominated for vice president by a major U.S. political party. In 1992 and 1998 she ran unsuccessfully for the U.S. Senate.
ferret Either of two species in the carnivore family Mustelidae. The common ferret (Mustela putorius furo) is a domesticated form of the European polecat. It has a long, lithe body and is brown, black, or white (albino). Its average length is 20 in. (51 cm), including the 5-in. (13-cm) tail, and it weighs about 2 lbs (1 kg). It was originally domesticated for hunting mice, rats, and rabbits; today ferrets are commonly kept as pets. The black-footed ferret (M. nigripes), of the North American plains, has a black mask across the eyes and brownish black markings on the feet and tail tip. It is an endangered species, owing to the loss of its main source of food, the prairie dog.
ferrimagnetism Type of permanent magnetism that occurs in solids, in which the magnetic fields associated with individual atoms spontaneously align themselves, some parallel (as in ferromagnetism), and others anti¬ parallel, or paired off in opposite directions (as in antiferromagnetism). The materials are less magnetic than ferromagnets, as the antiparallel atoms dilute the magnetic effect of the parallel arrangement. Ferrimag¬ netism occurs mainly in magnetic oxides known as ferrites. Above a tem¬ perature called the Curie point, the spontaneous alignment is disrupted and ferrimagnetism is destroyed, but it is restored upon cooling below the Curie point.
ferroalloy Alloy of iron (less than 50%) and one or more other metals, important as a source of various metallic elements in the production of alloy steels. The principal ferroalloys are ferromanganese, ferrochromium, ferromolybdenum, ferrotitanium, ferrovanadium, ferrosilicon, ferroboron, and ferrophosphorus. They usually have lower melting ranges than do the pure elements and can be incorporated more readily in the molten steel. Ferroalloys are prepared from charges of the nonferrous metal ore, iron or iron ore, coke or coal, and flux by treatment at high temperature in submerged-arc electric furnaces.
ferromagnetism Physical phenomenon in which certain electrically uncharged materials strongly attract others. It is associated with iron, cobalt, nickel, and some alloys or compounds containing these elements. It is caused by the alignment patterns of the material’s atoms, each of which acts as a simple electromagnet, due to the motion and spin of the
electrons. The tiny magnets spontaneously align themselves in the same direction, so their magnetic fields reinforce each other. Ferromagnetic mate¬ rials are magnetized easily. Above a temperature called the Curie point, they cease to be magnetic, but they become ferromagnetic again upon cooling below the Curie point. See also ferrimagnetism.
Ferry \fe-'re\, Jules (-Francois-Camille) (b. April 5, 1832, Saint- Die, France—d. March 17, 1893, Paris) French politician. He held a num¬ ber of offices in the early Third Republic, including mayor of Paris (1870) and premier of France (1880-81, 1883-85). His government established free, compulsory, secular education (1882), enacting such anticlerical measures as dissolving the Jesuits and forbidding their members to teach. Ferry played a major part in extending France’s colonial territories in Asia and Africa, but public anger for colonial expenditures forced his resigna¬ tion, though he was later elected to the Senate. He was assassinated by a madman.
Fertile Crescent Region, Middle East. The term describes a crescent¬ shaped area of arable land, probably more agriculturally productive in antiquity than it is today. Historically the area stretched from the south¬ eastern coast of the Mediterranean Sea around the Syrian Desert north of the Arabian Peninsula to the Persian Gulf; in general, it often includes the Nile River valley as well. Sedentary agricultural settlements in the Fertile Crescent can be dated to c. 8000 bc. It was the scene of the struggles and migrations of some of the earliest known peoples, including Sumerians, Assyrians, Akkadians, various Semitic groups, Babylonians, and Phoeni¬ cians.