Liege Vlyezh\ Flemish Luik Vloik\ City (pop., 2000 est.: 185,639), east¬ ern Belgium. Located at the confluence of the Meuse and Ourthe rivers, it was inhabited in prehistoric times and was known to the Romans as Leo- dium. It became a town when St. Hubert transferred his see there in 721, and it was noted as a centre of learning in the Middle Ages. Annexed to France in 1795, it was later assigned with the rest of Belgium to The Netherlands in 1815. A centre of the successful revolt for Belgian inde¬ pendence in 1830, it is now an industrial research centre and a major port.
liege \lej\ In European feudal society, an unconditional bond between a man and his overlord. Thus, if a tenant held estates from various over- lords, his obligations to his liege lord, to whom he had paid “liege hom¬ age,” were greater than his obligations to the other lords, to whom he had paid only “simple homage.” See also feudal land tenure.
lien \len\ In law, a charge or encumbrance on property for the satisfac¬ tion of a debt or other duty. Common law developed two kinds of posses¬ sory lien: the specific (a lien on the specific property involved in a
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© 2006 Encyclopaedia Britannica, Inc.
1112 I Liezi ► light-emitting diode
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transaction) and the general (a lien for the satisfaction of a balance due, not confined to a specific property involved in a transaction). Courts of equity may, through the device of the equitable lien, recognize a creditor’s interest in a debtor’s property. Statutory liens are also available; devel¬ opers and building contractors, for example, may use their interest in an improved site as security for payment (a mechanic’s lien).
Liezi or Lieh-tzu Vlye-'dzoX (fl. 4th century bc, China) Chinese Daoist philosopher. He was one of the three primary philosophers who devel¬ oped the tenets of Daoist thought, and he is the presumed author of the Daoist work Liezi. Many of the writings traditionally attributed to him have been identified as later forgeries, but he is still widely believed to have been a historical figure.
Liezi or Lieh-tzu Chinese Daoist classic. Though Liezi is traditionally named as its author, in its present form it probably dates from the 3rd or 4th century ad. Like earlier Daoist classics, it emphasizes the mysterious dao (way). The “Yang Zhu” chapter acknowledges the futility of chal¬ lenging the dao and asserts that all one can look forward to in life is sex, music, physical beauty, and material abundance. This fatalistic belief in a life of radical self-interest was a new development in Daoism.
Lifar Vle-.farV, Serge (b. April 2, Empire—d. Dec. 15, 1986, Lau¬ sanne, Switz.) Russian-born French dancer, choreographer, and ballet master. In 1923 he joined the Ballets Russes, where he became lead dancer in 1925 and created title roles in sev¬ eral of George Balanchine’s ballets.
He worked at the Paris Opera Ballet as lead dancer and ballet master (1929^-5, 1947-58), choreograph¬ ing more than 50 works, including Prometheus (1929), Icarus (1935), Les Mirages (1947), and Les Noces
1905, Kiev, Ukraine, Russian
Lifar in Night, 1930
BBC HULTON PICTURE LIBRARY
fantastiques (1955). He rebuilt the company as a separate performing
group, emphasizing the importance of male dancers. He retired as a dancer in 1956 but continued to choreograph for various European companies.
life State characterized by the ability to metabolize nutrients (process materials for energy and tissue building), grow, reproduce, and respond and adapt to environmental stimuli. Fossil evidence suggests that earth’s first living organisms, bacteria and cyanobacteria, arose about 3.5 billion years ago. All known life-forms possess either DNA or RNA. Viruses, which possess DNA and RNA, cannot reproduce without a host cell and do not metabolize nutrients, and it is uncertain whether they should be classified as living or nonliving. Scientists disagree on the likelihood of extraterrestrial life. See also Drake equation.
Life U.S. picture magazine published weekly in New York City from 1936 to 1972 and in special editions thereafter. One of the most popular and widely imitated of U.S. magazines, it was founded by Henry R. Luce and quickly became a cornerstone of Time-Life Publications. From the start it emphasized photography, with gripping, superbly chosen news photo¬ graphs, photographic features, and photo-essays by the best photogra¬ phers; gradually more writing was added. Its war coverage—particularly that of World War II—was notably vivid, authentic, and moving. Life ceased publication largely because its costs outstripped revenues. It reap¬ peared in special issues and then, from 1978 to 2000, as a monthly.
life insurance Method by which large groups of individuals equalize the burden of financial loss from death by distributing funds to the ben¬ eficiaries of those who die. Life insurance is most developed in wealthy countries, where it has become a major channel of saving and investing. There are three basic types of life-insurance contract. Term insurance is issued for a specified number of years; protection expires at the end of the period and there is no cash value remaining. Whole-life contracts run for the whole of the insured’s life and also accumulate a cash value, which is paid when the contract matures or is surrendered; the cash value is less than the policy’s face value. Endowment contracts run for a specified time period and pay their full face value at the end of the period.
life span Time between birth and death. It ranges from a mayfly’s day to certain trees’ thousands of years. Its limit appears to depend on hered¬ ity, but such factors as (in humans) disease, natural disasters, war, diet,
and habits such as smoking reduce it. Maximum life span is theoretical; more meaningful is average life span, which life-insurance companies and actuaries analyze and tabulate. Long-lived progenitors tend to beget long- lived descendants. A very-low-calorie diet appeal’s to prolong life. Reduced infant mortality and improved sanitation and nutrition account for much of the increase since c. 1800—from about 35 to over 70 years in most industrialized countries. The oldest well-documented age reached by a human is 122 years.
Liffey, River River, Ireland. Rising southwest of Dublin, it flows north¬ west, then runs west in the Kildare lowland. It crosses east through Dub¬ lin, where it is channeled into canals, and empties into Dublin Bay, an arm of the Irish Sea, after a course of 50 mi (80 km). The river is per¬ sonified as Anna Livia Plurabelle in James Joyce’s Finnegans Wake.
lift Upward-acting force on an aircraft wing or airfoil. An aircraft in flight experiences an upward lift force, as well as the thrust of the engine, the force of its own weight, and a drag force. The lift force arises because the speed at which the displaced air moves over the top of the airfoil (and over the top of the attached boundary layer) is greater than the speed at which it moves over the bottom and because the pressure acting on the airfoil from below is therefore greater than the pressure from above.
lift-slab construction Technique whereby concrete floor slabs are poured on the ground, one on top of the other, and then lifted into place on top of columns by hydraulic jacks. Used for very tall multistory build¬ ings, this method offers substantial savings in formwork.
ligament Tough fibrous band of connective tissue that supports internal organs and holds bones together properly in joints. It is composed of dense bundles of fibres and spindle-shaped cells (fibroblasts and fibrocytes), with little ground substance. White ligament is rich in sturdy, inelastic collagen fibres; yellow ligament is rich in tough elastic fibres, which allow more movement. See also tendon.
ligand Vli-gond, 'll-gondV Atom, group (see functional group), or mol¬ ecule attached to a central atom, usually of a transition element, in a coor¬ dination or complex compound (see bonding). It is almost always the electron-pair donor (nucleophile) in a covalent bond. Common ligands include the neutral molecules water (H 2 0), ammonia (NH 3 ), and carbon monoxide (CO) and the anions cyanide (CN - ), chloride (Cl - ), and hydrox¬ ide (OH - ). Rarely, ligands are cations and electron-pair acceptors (elec¬ trophiles). Organic ligands include EDTA (see chelate) and nitrilotriacetic acid. Biological systems rely on ligands such as the porphyrin in hemoglo¬ bin and chlorophyll, and numerous cofactors are ligands. In chelates, the ligand attaches at more than one point, sharing more than one electron pair, and is called bidentate or polydentate—having two or many “teeth.” The ligands in a complex may be the same or different.