bolur-e âvé (#)
Fr.: cristaux liquides
A type of material that possesses less geometrical regularity or order than normal solid crystals, and whose order varies in response to alterations in temperature, electric field, and other quantities.
Fr.: hélium liquide
The state of helium (4He) below its boiling point of 4.2 K. Its normal form is called → helium I, but converts into superfluid → helium II below 2.17 K (→ lambda point). Liquid helium is colorless and transparent so that it is impossible to see the surface of the liquid with the naked eye. Helium was first liquefied in 1911 by the Dutch physicist Heike Kamerlingh Onnes (1853-1936), Physics Nobel Prize 1913.
Fr.: miroir liquide
A mirror composed of liquid, taking advantage of the parabolic shape of a spinning liquid and the fact that the mirror's focal length can be adjusted by altering the velocity at which the liquid's container spins.
Fr.: eau liquide
Water in a state that is neither ice nor vapor.
In the → phase diagram of a → mixture (such as an → alloy) at constant pressure, the → curve that separates the all liquid phase from the liquid+solid phase. Below the liquidus the mixture will be partly or entirely → solid. See also → solidus.
From L. liquidus, → liquid.
Fr.: LISA Pathfinde
An → ESA spacecraft that was launched on December 3, 2015 to test technologies needed for the Evolved Laser Interferometer Space Antenna (eLISA), an ESA → gravitational wave observatory planned to be launched in 2034. LISA Pathfinder paves the way for future missions by testing in flight the very concept of gravitational wave detection.
xam-e Lissajous (#)
Fr.: courbe de Lissajous, figure de ~
A curve traced out by a point which is oscillating simultaneously in two mutually perpendicular directions. In general, the amplitude and frequency may be different in the two directions, and the two oscillations may have an arbitrary initial phase difference. The simplest pattern is a straight line, being obtained from two oscillations of equal frequency in phase with each other. The patterns can become very involved if the ratio of the frequencies is not a simple one.
After the French physicist Jules Antoine Lissajous (1822-1880), who first demonstrated such curves (Comptes-Rendus, 1857, 44, 727); → figure.
Xam, → curve.
Fr.: orbite de Lissajous
A quasi-periodic path resembling a → Lissajous figure around the L1 or L2 → Lagrangian points of a two-body system. Lissajous orbits, resulting from a combination of planar and vertical components, are used by certain space telescopes (such as → WMAP, → Planck Satellite, and → Herschel Satellite) that are required to be in a stable position relative to the Earth and Sun while making long-term observations.
A metric unit of volume, formerly defined as the volume of one kilogram of pure water under standard conditions; now equal to 1 cubic decimeter (dm3); hence 1 liter = 0.001 m3 and 1000 liter = 1 m3.
From Fr. litre, from litron, obsolete Fr. measure of capacity for grain, from M.L. litra, from Gk. litra "pound."
1) Writings in which expression and form, in connection with ideas of
permanent and universal interest, are characteristic or essential
features, as poetry, novels, history, biography, and essays.
From L. literatura/litteratura "writing, grammar, learning," from litera/littera "letter."
Neveštârgân, from neveštâr, literally "written; writing," verbal noun from neveštan, nevis- "to write;" Mid.Pers. nibištan, nibes- "to write;" Av./O.Pers. nī- "down; in, into," → ni- (PIE), + paēs- "to paint; to adorn," paēsa- "adornment" (Mid.Pers. pēsīdan "to adorn"); O.Pers. pais- "to adorn, cut, engrave" (Mod.Pers. pisé "variegated"); cf. Skt. piśáti "adorns; cuts;" Gk. poikilos "multicolored;" L. pingit "embroiders, paints;" O.C.S. pisati "to write;" O.H.G. fēh "multicolored;" Lith. piēšti "to draw, adorn;" PIE base *peik- "colored, speckled," + -gân suffix of suffix forming plural entities, from Mid.Pers. -gânag.
A metallic → chemical element; symbol Li.
→ Atomic number 3;
→ atomic weight 6.941;
→ melting point about 180.54°C;
→ boiling point about 1,342°C.
Lithium is a soft, silver-white metal. It is the lightest
metal and one of the alkali metals in Group 1 of the → periodic table.
Lithium does not occur on Earth in its free form. It is a minor
part of almost all igneous rocks and is found in many natural brines,
in total 0.0007% of the Earth's crust. It has two stable
→ isotopes, 7Li (92.5%) and 6Li (7.5%).
The element was discovered in the mineral
petalite, LiAl(Si2O5)2, by the Swedish mineralogist Johan August
Arfwedson in 1817. It was isolated by W.T. Brande and Sir Humphrey
Davy. Many uses have been found for lithium and its compounds. Lithium
has the highest → specific heat (3.6 J/gK)
of any solid element and is used in heat transfer applications. It is used in
rechargeable lithium ion batteries. It is also used as an alloy with
→ aluminum, → copper, and
→ manganese to make high performance aircraft parts. It is
used to make special glasses and ceramics, including the Mount Palomar
telescope's 5 m mirror. Lithium also has various nuclear applications,
for example as a coolant in nuclear breeder reactors and a source of
→ tritium, which is formed by bombarding lithium with neutrons. In
medicine it is used to treat bipolar disorder (manic depression), a
serious mental illness that causes extreme shifts in mood, energy, and
Lithium, from L. lithos "stone" because lithium was thought to exist only in minerals.
lithium I line
xatt-e litiom I
Fr.: raie de lithium I
setâre-ye litiomi (#)
Fr.: étoile à lithium
A peculiar evolved star of spectral type G or M whose spectrum displays a high abundance of lithium.
Fr.: test du lithium
The presence or not of the lithium absorption line at 6708 Å, which is considered to be a sufficient condition for → substellarity in → L dwarfs. It has been shown that any object with lithium absorption and → effective temperature less than 2670 K is a → brown dwarf. For a discussion of potential problems with the lithium test see Kirkpatrick et al. (1993, ApJ 406, 701).
The solid portion of the → Earth, as compared to the → atmosphere and the → hydrosphere. The lithosphere consists of semi-rigid plates that move relative to each other on the underlying → asthenosphere. The process is known as → plate tectonics and helps explain → continental drift.
From litho- a combining form of Gk. lithos "stone," + → sphere.
haft xâharân (#), camce-ye kucak (#)
Little, from M.E., O.E. lytel, from W.Gmc. *lutila- (cf. Du. luttel, O.H.G. luzzil, Ger. lützel, Goth. leitils), from PIE *leud- "small;" dipper, from dip, O.E. dyppan "immerse," from P.Gmc. *dupjanan.
Haft xâharân "the seven sisters," from haft "seven"
(Mid.Pers. haft; Av. hapta; cf. Skt. sapta; Gk. hepta;
L. septem; P.Gmc. *sebun; Du. zeven; O.H.G. sibun;
Ger. sieben; E. seven; PIE *septm)
+ xâharân plural of xâhar "sister;" Mid.Pers. xwâhar
"sister;" Av. xvanhar- "sister;" cf. Skt. svásar- "sister;"
Sogdian xwār; Gk. eor; L. soror (Fr. soeur);
O.C.S., Rus. sestra; Lith. sesuo; O.Ir. siur; Welsh chwaer;
M.Du. suster; Du. zuster; O.H.G. swester;
Goth. swistar; Ger. Schwester;
Swed. sister; Dan. søster;
O.E. sweostor, swuster; E. sister.
Little Ice Age
asr-e yax-e kucek
Fr.: petit âge glaciaire
A roughly 400-year period from the mid-16th through the mid-19th centuries when temperatures over much of Europe were unusually cold. Glaciers in the Alps advanced and European rivers froze much more often than during the past century. Harvests failed, livestock perished, and poor people suffered from famine and disease. The Little Ice Age coincided with two successive low → solar activity periods, the → Sporer minimum and the → Maunder minimum.
Fr.: prisme de Littrow
A prism having angles of 30, 60, and 90°, which uses the same face for input and dispersed radiation. The beam is reflected at the face opposite to the 60° angle because it is coated to be highly reflecting. A beam entering at the → Brewster angle undergoes minimum deviation and hence maximum dispersion. Littrow prisms are used in laser cavities to fine tune lasers by selection of wavelength.
Joseph Johann Littrow (1781-1840), Austrian astronomer; → prism.
âyene-ye Lloyd (#)
Fr.: miroir de Lloyd
An optical arrangement in which light from a source is allowed to fall on a plane mirror at → grazing incidence. The light directly coming from the source interferes with the light reflected from the mirror forming an → interference pattern. See also → Fresnel's biprism, → Fresnel's mirrors.
After the Irish physicist Humphry Lloyd (1800-1881); → mirror.
1) bâr; 2) bâr kardan (#)
Fr.: 1) charge; 2) charger
1) Something that is borne or carried.
From M.E. lode, originally the same word as lode, from O.E. lāad "way, course, carrying;" cf. O.N. leith "way, route," O.H.G. leita "procession."
Bâr kardan "to load," composite verb from bâr "load, charhe, burden," (Mid.Pers. bâr, from O.Pers./Av. base bar- "to bear, carry;" Mod.Pers. bordan "to carry;" L. brutus "heavy, dull, stupid, brutish;" Skt. bhara- "burden, load," bharati "he carries;" Gk. baros "weight;" Mod.Pers. gerân "heavy;" Skt. guru; L. gravis; PIE *gwere- "heavy," *bher- "carry, give birth") + kardan "to do, to make" (Mid.Pers. kardan; O.Pers./Av. kar- "to do, make, build;" Av. kərənaoiti "he makes;" cf. Skt. kr- "to do, to make," krnoti "he makes, he does," karoti "he makes, he does," karma "act, deed;" PIE base kwer- "to do, to make").