An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 86 Search : action
 packing fraction   برخه‌ی ِ انباشتگی   barxe-ye anbâštegi (#)Fr.: coefficient de tassement   The difference between the isotopic mass of a nuclide and its mass number divided by its mass number. The packing fraction is a measure of the stability of the nucleus.Packing, from the verb pack "to put together in a pack," from the noun pack, from M.E. pak, packe, from M.D. pac or perhaps M.L.G. pak; → fraction.Barxé, → fraction; anbâštegi quality noun of anbâštan, anbârdan "to fill, to replete;" Mid.Pers. hambāridan "to fill;" from Proto-Iranian *ham-par-, from prefix ham- + par- "to fill;" cf. Av. par- "to fill," parav-, pauru-, pouru- "full, much, many;" O.Pers. paru- "much, many;" Mid.Pers. purr "full;" Mod.Pers. por "full, much, very;" PIE base *pelu- "full," from *pel- "to be full;" cf. Skt. puru- "much, abundant;" Gk. polus "many," plethos "great number, multitude;" O.E. full. polarization fraction   برخه‌ی ِ قطبش   barxe-ye qotbešFr.: fraction de polarisation   The ratio expressed by P = (Ipar - Iper) / (Ipar + Iper), where Ipar and Iper are the light intensities with the electric field vector respectively parallel and perpendicular to the incident beam.→ polarization; → fraction. principle of action and reaction   پَروز ِ ژیرش و واژیرش، ~ کنش و واکنش   parvaz-e žireš va vâžireš, ~ koneš va vâkonešFr.: principe d'action et de réaction   Newton's third law of motion, which states that for every action there must be an equal and opposite reaction.→ principle; → action; → reaction. principle of least action   پَروز ِ کمترین ژیرش، ~ ~ کنش   parvaz-e kamtarin žireš, ~ ~ konešFr.: principe de moindre action   The principle that, for a system whose total mechanical energy is conserved, the path to be taken for the system from one configuration to another is the one whose action has the least value relative to all other possible paths and from the same configurations. Also called Maupertuis' principle, least-action principle.→ principle; → least; → action. proton-proton reaction   واژیرش ِ پروتون-پروتون   vâžireš-e-e proton-protonFr.: réaction proton-proton   A → thermonuclear reaction in which two protons collide at very high velocities and combine to form a → deuterium. See also → proton-proton chain.→ proton; → reaction. pycnonuclear reaction   واژیرش ِ چگال‌هسته‌ای   vâžireš-e cagâl-hasteyiFr.: réaction pycnonucléaire   A nuclear reaction that takes place at high densities and relatively low temperatures. Pycnonuclear reactions are almost temperature independent and occur even at zero temperature. These reactions are extremely slow at densities typical for normal stars but intensify with increasing density. For example, carbon burns into heavier elements at densities over 1010 g cm-3.Pycnonuclear, from pycno- a combining form meaning "dense, thick," from Gk. pyknos "dense, solid" + → nuclear; → reaction.Vâžireš, → reaction; cagâl-hasteyi, from cagâl, → dense, + hasteyi, → nuclear. quantum of action   کو‌آنتوم ِ ژیرش   kuântom-e žirešFr.: quantum d'action   Since → Planck's constant has the dimension of → energy × → time, its sometimes called the quantum of → action.→ quantum; → action. rarefaction   آلرش   âlarešFr.: raréfaction   The state of being rarefied, less dense. An instantaneous reduction in density of a gas resulting from passage a sound wave; opposite of → compression.M.E. rarefien, from M.Fr. rarefier, from L. rarefacere "make rare," from rarus "loose, wide apart, thin, infrequent."Verbal noun from âlar present stem of âlaridan→ rarefy + -š, a suffix. rarefaction wave   موج ِ آلرش   mowj-e âlarešFr.: onde de raréfaction   A pressure wave in a fluid generated by rarefaction. It travels in the opposite direction to that of a shock wave in the medium.→ rarefaction; → wave. reaction   واژیرش، واکنش   vâžireš, vâkonešFr.: réaction   1) General: Action in response to some influence, event, stimulus. 2) An equal and opposite force exerted by a body against a force acting upon it. → principle of action and reaction. 3) A → nuclear reaction; → chain reaction. 4) → chemical reaction.Verbal noun of → react. reaction rate   نرخ ِ واژیرش   nerx-e vâžirešFr.: taux de réaction   The speed with which a → chemical reaction takes place. In other words, the change in → concentration of a → substance divided by the → time interval during which the change is observed.→ reaction; → rate. refraction   شکست   šekast (#)Fr.: réfraction   1) Optics: The change of direction which a beam of light undergoes as it enters a medium of different → refractive index. 2) Acoustics: The change in direction in sound waves on reaching the boundary between two media. 3) Seismology: The bending of a seismic wave as it enters a material of different density.From L.L. refractionem (nominative refractio) "a breaking up," from L. refractus, p.p. of refringere "to break up," from re- "back" + combining form of frangere "to break," from PIE base *bhreg- "to break" (cf. Goth. brikan, O.E. brecan "to break;" Lith. brasketi "crash, crack").Šekast, past stem of šekastan "to break, split;" Mid.Pers. škastan "to break;" Av. scind-, scand "to beak, cleave;" Proto-Iranian *skand- "to break, cleave;" PIE sken- "to cut off." resonant reaction   واژیرش ِ باز‌آوا   vâžireš-e bâzâvâFr.: réaction résonnante   A nuclear reaction whose probability is enhanced at an energy corresponding to an energy level of one of the nuclei. → resonance capture.Resonant, verbal adj. of → resonate; → reaction. screened Coulomb interaction   اندرژیرش ِ باپرده‌ی ِ کولن   andaržireš-e bâparde-ye CoulombFr.: interaction de Coulomb écrantée   The → Coulomb interaction reduced owing to the presence of other electrons. See → shielding effect.→ screen; → coulomb; → interaction. simple fraction   برخه‌ی ِ ساده   barxe-ye sâdéFr.: fraction simple   A fraction in which the → numerator and → denominator are positive → integer numbers. Compare → compound fraction.→ simple; → fraction. sky subtraction   زیرکرشش ِ آسمان   zirkaršeš-e âsmânFr.: soustraction de ciel   The act or instance of removing the contribution of non-related, intervening foreground light to the object.→ sky; → subtraction. strong interaction   اندرژیرش ِ سترگ   andaržireš-e sotorgFr.: interaction forte   The interaction between quarks that is transmitted by gluons. The characteristic range of the strong interaction is 10-13 cm, and the time scale over which it operates is on the order of 10-23 second. Also called → strong force.→ strong; → interaction. subtraction   زیرکرشش   zirkaršešFr.: soustraction   The operation of finding the difference between two numbers or quantities.Verbal noun of → subtract. tensor contraction   ترنگش ِ تانسور   terengeš-e tânsorFr.: contraction de tenseur   An operation of tensor algebra that is obtained by setting unlike indices equal and summing according to a summation convention.→ contraction; → tensor. thermonuclear reaction   واژیرش ِ گرماهسته‌ای   vâžireš-e garmâhaste-yi (#)Fr.: réaction thermonucléaire   A nuclear reaction in which two or more atomic nuclei fuse into a single heavier nucleus by a collision of the interacting particles at extremely high temperatures. Chains of thermonuclear reactions, such as the → proton-proton chain and the → CNO cycle, account for the energy radiated from the Sun and more massive stars.→ thermo- + → nuclear; → reaction.