Fr.: critère de Ledoux
An improvement of → Schwarzschild's criterion for convective instability, which includes effects of chemical composition of the gas. In the Ledoux criterion the gradient due to different molecular weights is added to the adiabatic temperature gradient.
After the Belgian astrophysicist Paul Ledoux (1914-1988), who studied problems of stellar stability and variable stars. He was awarded the Eddington Medal of the Royal Astronomical Society in 1972 (Ledoux et al. 1961 ApJ 133, 184); → criterion.
Of, pertaining to, or located on or toward the west when somebody or something is facing north. Opposite of → right.
M.E. left, lift, luft, O.E. left, lyft- "weak, idle," cf. Ger. link, Du. linker "left," from O.H.G. slinc, M.Du. slink "left," Swed. linka "limp," slinka "dangle."
Cap "left," from unknown origin.
razan-e dast-e cap
Fr.: règle de la main gauche
See → Fleming's rules.
capâl (#) , capdast (#)
Using the left hand with greater ease than the right.
1) Permitted by law; lawful.
From M.Fr. légal or directly from L. legalis "legal, pertaining to the law," from lex (genitive legis) "law."
Qânuni, of or relating to qânun, → law.
1) A non-historical or unverifiable story handed down by tradition from
earlier times and popularly accepted as historical.
M.E. legende "written account of a saint's life," from O.Fr. legende and directly from M.L. legenda literally, "(things) to be read," noun use of feminine of L. legendus, gerund of legere "to read" (on certain days in church).
Cirok, from Kurd. cirok "story, fable," related to Kurd. cir-, cirin "to sing, [to recite?];" Av. kar- "to celebrate, praise;" Proto-Ir. *karH- "to praise, celebrate;" cf. Skt. kar- "to celebrate, praise;" O.Norse herma "report;" O.Prussian kirdit "to hear;" PIE *kerH2- "to celebrate" (Cheung 2007).
Of, relating to, or of the nature of a legend.
Fr.: équation de Legendre
The → differential equation of the form: d/dx(1 - x2)dy/dx) + n(n + 1)y = 0. The general solution of the Legendre equation is given by y = c1Pn(x) + c2Qn(x), where Pn(x) are Legendre polynomials and Qn(x) are called Legendre functions of the second kind.
Named after Adrien-Marie Legendre (1752-1833), a French mathematician who made important contributions to statistics, number theory, abstract algebra, and mathematical analysis; → equation.
Fr.: transformation de Legendre
A mathematical operation that transforms one function into another. Two differentiable functions f and g are said to be Legendre transforms of each other if their first derivatives are inverse functions of each other: df(x)/dx = (dg(x)/dx)-1. The functions f and g are said to be related by a Legendre transformation.
1) The act of making or enacting laws.
From Fr. législation, from L.L. legislationem, from legis latio, "proposing (literally 'bearing') of a law," → legislator.
Qânungoz&acric;ri "act or process followed by the qânungoz&acric;r", → legislator.
1) A person who gives or makes laws.
From L. legis lator "proposer of a law," from legis, genitive of lex, → law, + lator "proposer," agent noun of latus "borne, brought, carried."
Qânungozâr, literally "he who places the law," from qânun, → law, + gozâr, present stem and agent noun of gozâštan "to place, put; perform; allow, permit," related to gozaštan "to pass, to cross," → trans-
giti-ye Lemaître (#)
Fr.: Univers de Lemaître
A cosmological hypothesis, based on Einstein's relativity, in which the expanding Universe began from an exploding "primeval atom." In the Lemaître Universe the rate of expansion steadily decreases.
Named after Monsignor Georges Edouard Lemaître (1894-1966), a Belgian Roman Catholic priest, honorary prelate, professor of physics and astronomer; → universe.
1) A subsidiary proposition, proved for use in the proof of another proposition.
From L. lemma, from Gk. lemma "something received or taken; an argument; something taken for granted," from root of lambanein "to take," → analemma.
Nehak, from neh present stem of nehâdan "to place, put; to set," → position, + -ak a diminutive suffix of nouns.
lemniscate of Bernoulli
Fr.: lemniscate de Bernoulli
A closed curve with two loops resembling a figure 8. It is represented by the Cartesian equation (x2 + y2)2 = a2(x2 - y2), where a is the greatest distance from the origin (pole) to the curve. Its polar equation is r2 = a2 cos 2θ.
From L. Latin lemniscatus "adorned with ribbons," from lemniscus "a pendent ribbon," from Gk. lemniskos "ribbon;" First described by Jacques Bernoulli (1654-1705) in 1694.
derâzâ (#), tul (#)
A distance determined by the extent of something specified. → Jeans length
M.E. length(e), O.E. lengthu "length," from P.Gmc. *langitho, noun of quality from *langgaz (root of O.E. lang "long," cognate with Pers. derâz, as below) + -itho, abstract noun suffix. Cognate with O.N. lengd, O.Fris. lengethe, Du. lengte.
Derâzâ quality noun of derâz "long," variants Laki, Kurdi derež; Mid.Pers. drâz "long;" O.Pers. dargam "long;" Av. darəga-, darəγa- "long," drājištəm "longest;" cf. Skt. dirghá- "lon (in space and time);" L. longus "long;" Gk. dolikhos "elongated;" O.H.G., Ger. lang; Goth. laggs "long;" PIE base *dlonghos- "long;" tul loan from Ar. ţaul, used in → wavelength.
Fr.: contraction de longueur
Same as → Lorentz contraction.
Fr.: long, interminable
1) Having or being of great length; very long.
From → length + -y.
Kešnâk "lengthy" (Bardsiri, Kermâni), from kešidan, kašidan "to draw, protract, trail, drag, carry," → tide. Bardesir, Kermân
A transparent optical component consisting of one or more pieces of optical glass with surfaces so curved (usually spherical) that they serve to converge or diverge the transmitted rays from an object, thus forming a real or virtual image of that object.
From L. lens (gen. lentis) "lentil," cognate with Gk. lathyros, on analogy of the double-convex shape.
Adasi, related to adas "lentil," from Ar. 'adas.
Fr.: système de lentilles
Fr.: effet Lense-Thirring
An effect predicted by → general relativity whereby a rotating body alters the → space-time around it. This effect can be thought of as a kind of "dragging of inertial frames," as first named by Einstein himself. A massive spinning object pulls nearby objects out of position compared to predictions for a non-rotating object. The effect is important for rapidly rotating → neutron stars and → black holes, but that near Earth is extraordinarily small: 39 milli-arc second per year, about the width of a human hair seen from 400 meters away.
Named after Austrian physicists Joseph Lense (1890-1985) and Hans Thirring (1888-1976), who first discovered this phenomenon in 1918; → effect.