fibre optics Thin transparent fibres of glass or plastic that transmit light through their length by internal reflections, used for transmitting data, voice, and images. Fibre-optic technology has virtually replaced copper wire in long-distance telephone lines and is used to link computers in local area networks, with digitized light pulses replacing the electric current formerly used for the signal. Telecommunication using fibre optics is usu¬ ally conducted with infrared light. Fibre optics uses light in the visible wavelengths to transmit images directly, in various technical devices such as those developed for endoscopy.
fibreglass or glass fibre Fibrous form of glass, developed in the 1930s. Liquid glass issues in fine streams through hundreds of fine nozzles, and the solidifying streams are gathered into a single strand and wound onto a spool. Strands can be twisted into yams, woven into fab¬ rics, or chopped into short pieces and then bonded into mats. Glass fila¬ ments and yams add strength and electrical resistivity to molded plastic products. Glass fabrics are used as electrical insulators and as reinforc¬ ing belts in automobile tires. Discontinuous fibres are formed into wools, mats, or boards, commonly used in buildings, appliances, and plumbing.
fibrillation See atrial fibrillation, ventricular fibrillation fibrolite See sillimanite
fibromyalgia Chronic syndrome that is characterized by musculoskel¬ etal pain, often at multiple sites. The cause is unknown. A significant num¬ ber of persons with fibromyalgia also have mental disorders, especially depression. Many also have overlap¬ ping symptoms of other so-called functional somatic syndromes— especially chronic fatigue syndrome—such as fatigue, stiffness, irritable bowel syndrome, and sleep disturbances. It is common in young and middle-aged women. No treat¬ ment has been proved fully effective, although medications, physical therapy, or counseling may reduce disability and help the patient cope.
Fichte Vfik-t3\, Johann Gott¬ lieb (b. May 19, 1762, Rammenau,
Upper Lusatia, Saxony—d. Jan. 27,
1814, Berlin) German philosopher and patriot. Fichte’s Science of Knowledge (1794), a reaction to the critical philosophy of Immanuel Kant and especially to Kant’s Critique of
Johann Gottlieb Fichte, lithograph by F.A. Zimmermann after a painting by H.A. Daehling.
DEUTSCHE FOTOTHEK, DRESDEN, GER.
© 2006 Encyclopaedia Britannica, Inc.
Ficino ► Fielding I 671
Practical Reason (1788), was his most original and characteristic work. To demonstrate that practical reason is really the root of reason in its entirety, the absolute ground of all knowledge as well as of humanity altogether, he started from a supreme principle, the ego, which is inde¬ pendent and sovereign, so that all other knowledge is deducible from it. In his famous patriotic lectures Addresses to the German Nation (1807- OS) he attempted to rally German nationalists against Napoleon. He is regarded as one of the great transcendental idealists. His son Immanuel Hermann von Fichte (1796-1879) was also a philosopher.
Ficino Xfe-'che-noV Marsilio (b. Oct. 19, 1433, Figline, Republic of Florence—d. Oct. 1, 1499, Careggi, near Florence) Italian philosopher, theologian, and linguist. His translations and commentaries on the writ¬ ings of Plato and other Classical Greek authors marked the beginning of the Florentine Platonist Renaissance. In conceiving the universe as a hier¬ archy of substances that descends from God to matter, he was strongly influenced by Neoplatonism and medieval views. The Cambridge Platonists and related movements in France and Italy reflect Ficino’s interpretation of Platonism. Of his original writings, Platonic Theology (1482) and Book on the Christian Religion (1474) are most significant.
fiddler crab Any of about 65 species of decapods (genus Uca) whose males hold one claw, always much larger than the other, somewhat like a violin. Both claws of the female are relatively small. Fiddler crabs often live in large numbers on beaches in temperate to tropical regions of the world. They inhabit water-covered burrows up to about 1 ft (30 cm) deep and feed on algae and other organic matter. Common North American species (e.g., marsh fiddler, china-back fiddler) live all along the U.S. Atlantic coast. Brightly coloured, they range in body size from about 1 to 1.2 in. (2.5 to 3 cm).
Fides \'fi-dez\ Roman goddess of good faith and honesty, who oversaw the integrity of the Romans. She was closely associated with Jupiter, and her temple was built near his on the Capitoline Hill in 254 bc. In the later Roman period she was called Fides Publica (“Public Faith”) and was con¬ sidered the guardian of treaties and other state documents, which were placed in her temple for safekeeping.
fiduciary \f3-'du-she- l er-e\ In law, a person in a position of authority whom the law obligates to act solely on behalf of the person he or she represents and in good faith. Examples of fiduciaries are agents, execu¬ tors, trustees, guardians, and officers of corporations. Unlike people in ordinary business relationships, fiduciaries may not seek personal benefit from their transactions with those they represent.
Fiedler Vfed-larV, Arthur (b. Dec. 17, 1894, Boston, Mass., U.S.—d. July 10, 1979, Brookline, Mass.) U.S. conductor. Son of a distinguished violinist, he was trained in Berlin and joined the Boston Symphony Orchestra in 1915. In the 1920s he began conducting and recording with his own Boston Sinfonietta and various choral groups. In 1929 he orga¬ nized a series of open-air concerts, which was successful enough to even¬ tually become an institution, the Boston Pops. Thereafter his name was inextricably linked with the Pops, which achieved enormous success under his direction.
fief Vfef\ In European feudalism, a vassal’s source of income, granted to him by his lord in exchange for his services. The fief usually consisted of land and the labor of peasants who were bound to cultivate it. The income it provided supported the vassal, who fought for his lord as a knight. Dignities, offices, and money rents were also given in fief.
Field In physics, a region in which each point is affected by a force. Objects fall to the ground because they are affected by the force of earth’s gravitational field (see gravitation). A paper clip, placed in the magnetic field surrounding a magnet, is pulled toward the magnet, and two like magnetic poles repel each other when one is placed in the other’s mag¬ netic field. An electric field surrounds an electric charge; when another charged particle is placed in that region, it experiences an electric force that either attracts or repels it. The strength of a field, or the forces in a particular region, can be represented by field lines; the closer the lines, the stronger the forces in that part of the field. See also electromagnetic FIELD.
Field, Marshall (b. Aug. 18, 1834, near Conway, Mass., U.S.—d. Jan. 16, 1906, New York, N.Y.) U.S. department-store owner. Born on a farm, he became an errand boy for a dry-goods store at age 16. He moved to Chicago and was hired in 1856 by a mercantile house, in which he later attained full partnership. In 1867 he and a partner bought the merchan¬
dising firm they had joined two years earlier, and in 1888 he bought out his partner, creating Marshall Field and Co. In his store Field emphasized customer service, liberal credit, the one-price system, and the acceptance of returned merchandise. His department store was the first to have a res¬ taurant for shoppers.
Field, Sally (b. Nov. 6, 1946, Pasadena, Calif., U.S.) U.S. film actress. She played saccharine television roles in Gidget (1965-66) and The Fly¬ ing Nun (1967-70) before developing her talent at the Actors Studio (1973-75), from which she emerged as a dramatic actress in the televi¬ sion movie Sybil (1977, Emmy Award). Hollywood finally rewarded her with strong roles in Norma Rae (1979, Academy Award), Absence of Malice (1981), Places in the Heart (1984, Academy Award), and Steel Magnolias (1989). Her other films include Soapdish (1991), Mrs. Doubt- fire (1993), and Forrest Gump (1994).