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.
A period during which an eruptive astronomical phenomenon is in a state of inactivity.
Being at rest; quiet; still; inactive. → quiescent prominence.
From L. quiescens, pr.p. of quiescere, from quies "rest, quiet."
Âramidé "quiescent, reposed, rested," from âramidan "to rest, repose," related to ârâm "quiet" (Mid.Pers. râm "peace," râmenidan "to give peace, pleasure," râmišn "peace, pleasure" (Mod.Pers. râmiš), Av. ram- "to stay, rest;" cf. Skt. ram- "to stop, stand still, rest, become appeased;" Gk. erema "quietly, gently;" Goth. rimis "rest;" Lith. rãmas "rest").
Fr.: protuberance quiescente
A → solar prominence of relatively cool material that hovers over Sun's surface for weeks or months with relatively little overall change. Such prominences are suspended above the → chromosphere by → magnetic fields. A quiescent prominence may suddenly erupt outward and dissipate, often to be replaced, in the same location, by a new one. See also → eruptive prominence; → loop prominence.
Fr.: Soleil calme
The Sun when the 11-year cycle of → solar activity is at a minimum.
Quiet, M.E., from from O.Fr. quiete, from L. quies (genitive quietis) "rest, quiet;" → Sun.
panjomin gowhar (#)
In cosmology, a hypothetical new "element," distinct from any normalmatter (either → baryonic or not) or radiation, intended to explain the observed ever → accelerating expansion of the Universe. Quintessence can have several types and differs from the → cosmological constant in that it can vary in space and time. In modern physics, the four known "elements" are the → baryons (proton, neutron, etc.), the → leptons (neutrinos, electrons, etc.), the → photon, and the hypothetical → non-baryonic matter, which is thought to be 80% of the total matter in the Universe. The quintessence field is a possibility which can be confirmed or disproved by measurements of the → dark energy value at different → redshifts. In some models, the quintessence is fine-tuned to explain both the → cosmological constant problem and the → inflation in the very → early Universe.
Literally "fifth essence," from M.Fr. quinte essence, from M.L. quinta essentia, from L. quinta, fem. of quintus "fifth," from quinque "five," cognate with Pers. panj, → five + essentia "being, essence," from esse "being; → existence" + -entia "-ence." In Aristotelianism, the fifth element, distinguished from the four earthly elements, was the substance of celestial bodies. Subsequently, quintessence became the purest, most highly concentrated form of a nature or essence.
Panjomin gowhar "fifth essence," from panjomin "fifth," from panj, → five, cognate with L. quinque, + gowhar "essence, substance; jewel, pearl, gem," Mid.Pers. gohr "essence, substance; jewel; stock, lineage;" cf. Skt. gôtra- "family, race, lineage, origin."
Any group of five things or persons. → Stephan's Quintet.
From Fr. quintette, from It. quintetto, diminutive of quinto "fifth," from L. quintus, related to quinque "five" cognate with Pers. panj→ five.
Panjtâyé, from panj, → five, + tâ "fold, plait, ply, part;" Mid.Pers. tâg "piece, part" + -(y)é nuance suffix.
Math.: Of the fifth degree; a quantity of the fifth degree.
Panjomik, from panjom "fifth," from panj "five" + -om "-th" + -ik, → -ic.
Fr.: équation quintique
An equation containing unknowns of the fifth power.
Fr.: polynôme quintique
A polynomial of degree five.
Fr.: amas du quintuplet
A bright → open cluster of stars located within 100 light-years of the center of the Milky Way Galaxy, and one of the three → Galactic center clusters. The Quintuplet cluster was originally noted for its five very bright stars, but it is now known to contain many luminous → massive stars that are not detected at visible wavelengths due to heavy extinction by dust along the line of sight. The cluster is about 4 million years old and had an initial mass over 104 solar masses. The five brighter stars of the cluster are dusty → WC Wolf-Rayet stars. The Quintuplet cluster also contains two → Luminous Blue Variables, the Pistol star and FMM362. The Pistol star has a luminosity 107 times solar making it one of the most luminous stars known. The Quintuplet cluster is more dispersed than the nearby → Arches cluster.
Quintuplet, from the five brightest stars originally observed; → cluster.
1) General: A proportional part or share of a fixed total amount or quantity.
From L. quota pars "how big a share?," from quotus "of what number."
The number resulting from the division of one number by another. Also the fractional notation that indicates this number.
From L. quotiens "how many times," from quot "how many," related to quis "who."
Bahr "part, portion, share, lot," related to baxš "portion, part, division," baxšidan "to divide, distribute, grant" (Mid.Pers. baxt "fortune, fate," baxtan, baxšidan "to distribute, divide;" Av. base bag- "to attribute, allot, distribute," baxš- "to apportion, divide, give to," baxta- "what is allotted (luck, fortune)," baxədra- "part, portion," baγa- "master, god;" O.Pers. bâji- "tribute, tax;" cf. Skt. bhaj- "to share, divide, distribute, apportion," bhájati "divides," bhakta- "allotted; occupied with; a share; food or a meal, time of eating?" pitu-bháj- "enjoying food;" Gk. phagein "to eat (to have a share of food)"; PIE base *bhag- "to share out, apportion").