Fr.: lame quart d'onde
A plate of doubly refracting material cut parallel to the optic axis of the crystal and of such a thickness that a phase difference of 90° is introduced between the ordinary and extraordinary rays for light of a particular wavelength. → half-wave plate.
Fr.: équation quartique
An equation containing unknowns of the fourth power; the general form: ax4 + bx3 + cx2 + dx + e = 0.
In statistics, any of the four groups of a frequency distribution each containing 25% of the total number of individual observations.
From M.L. quartilis, from quart(us) "fouth" + -ilis "-ile" a suffix of adjectives expressing capability, susceptibility, liability, aptitude.
Cârakvâr, from cârak, → quarter, + -vâr suffix of similarity, size, aptitude.
From Ger. Quarz "rock crystal," from M.H.G. twarc.
kuâsâr (#), setârevaš (#)
An compact, extragalactic object which is highly luminous and looks like a star. Their redshifts can be large and their brightness varies. Quasars have an intrinsic luminosity which can reach some 100 times that of bright galaxies. They are thought to be active galactic nuclei with a size a little larger than the solar system. The first quasar to be identified as such, in 1963, was the radio source 3C 273 at a redshift of 0.158. With its 13th magnitude, it is the optically brightest quasar as observed from Earth. Some quasars are strong radio sources.
From quas(i) + (stell)ar (object).
A prefix meaning "resembling, almost, having some, but not all of the features of."
From L. quasi "as if, as though," from qua(m)" as" + si "if."
Cunân "so, like that; just as if," from cun "how?," (Mid.Pers. cigôn "how?," cigônêh "nature, character," O.Pers/Av. ci- "what, any," collateral stem to ka- "who?, what?;" cf. Skt. ka-; Gk. po-; L. quo-; E. what, who; PIE *qwos/*qwes) + suffix ân. -vaš a suffix of similitude.
A system in which the nuclei of two colliding atoms approach each other closely for a brief lapse of time so that their electrons are arranged in atomic orbitals characteristic of a single atom with combined atomic number.
Fr.: sous-système quasi-fermé
A subsystem if its intrinsic energy is large, on the average, with respect to the energy of its interaction with other portions of the → closed system.
Fr.: théorie quasi-linéaire
In plasma physics, the theory that considers the interactions between waves and particles are of first order only. It ignores all terms of second order in the fluctuating quantities.
An asteroid moving around the Sun having the same mean motion and mean → longitude as a planet, but a different → eccentricity. The asteroid remains near the planet much like a satellite even when its distance is large enough so that it is well outside the planet's → Hill sphere. The quasi-satellite motion is one class of possible → co-orbital motions of small bodies in 1:1 mean-motion → resonance with a planet. If the quasi-satellite orbit is coplanar with the planet, then the motion is stable in the → secular approximation. When the orbits are inclined enough, an asteroid can be trapped into such a motion for a finite period of time. Earth has several quasi-satellites (mainly 3753 Cruithne, 2002 AA29, 2003 YN107), also does Venus (the only one so far discovered, 2002 VE68). The possibility of such orbits was first suggested by J. Jackson (1913, MNRAS 74, 62).
quasi-separatrix layer (QSL)
Fr.: couche quasi-séparatrice
A region of the solar atmosphere where the gradient of the field line → linkage from one boundary to another is large so that the field lines can slip-run rapidly through the → plasma. The QSL results from → magnetic reconnection without → null point.
A model of radiative transfer that ignores forward scattering of photons; assuming forward-scattered light as un-scattered.
Fr.: objet quasi-stellaire
Initial name of → quasars.
quasi-stellar radio source
râdio-xan-e cunân setâré, ~ ~ setâré-vaš
Fr.: radiosource quasi-stellaire
A quasar with detectable radio emission.
A form of solid made up of ordered but non-repeating patterns of atoms, a symmetry that is forbidden for periodic crystals. In an ordinary crystal, only 1-, 2-, 3-, 4-, and 6-fold symmetries are possible, since these are the only symmetries that, when combined, can fill space. Prior to the discovery of quasicrystals, it was believed that 5-fold crystal symmetry could never occur. Quasicrystals are remarkable in that some of them display 5-fold or higher-fold forbidden symmetries. They are used as catalysts, in particular at high temperatures, to produce durable kinds of steel, like those used in objects such as razor blades and thin needles made specifically for eye surgery. The Nobel Prize in Chemistry 2011 was awarded to Daniel Schechtman for his discovery of quasicrystals in 1982.
Fr.: mouvement quasipériodique
In a dynamical system, a form of motion that is regular but never exactly repeating. Quasiperiodic motion appears when the system contains two or more incommensurate frequencies.
The last two million years of geologic time, comprising the Pleistocene and Holocene glacial epochs. Estimates of the date of the beginning of the Quaternary vary between 2.5 and 1.6 million years ago.
Quaternary, from L. quaternarius "consisting of four," from quatern(i) "fourt at a time" + -arius "-ary;" → period.
Dowrân, → period; cahârom "fourth," from cahâr "four" + -om "-th."
1) oserândan 2, 3) oseridan; 3) âb dâdan
Fr.: 1) étouffer, découper, étancher, assécher; 2) s'étouffer; 3) tremper
1a) To put out or extinguish.
M.E. quenchen, from O.E. acwencan "to quench," form of root of cwincan "to go out, be extinguished."
Oseridan, oserândan, from Yaghnobi oser- "to cool," Wakhi wəsər-/wəsərt "to fade, wither," related to Pers. sard "cold, cool" (Kurd. sar, Baluchi sârt, Ossetian sald "cold" ), afsordan, afsârdan "to congeal;" Mid.Pers. sard/sart "cold;" Av. sarəta- "cold;" cf. Skt. śiśira- "cold;" L. calidus "warm;" Lith. šaltas "cold;" Welsh clyd "warm;" PIE *keltos- "cool."
Fr.: fréquence de découpage
The frequency at which an oscillation is intermittently quenched, as in a super-regenerative receiver.
Fr.: étouffement, découpage, étanchement, assèchement; trempe
The process of extinguishing, removing, or diminishing a physical property.