Fr.: processus isotherme
A → thermodynamic process that takes place at → constant → temperature. For the temperature of a system to remain strictly constant, the changes in other coordinates (pressure and volume) must be carried out slowly, and → heat must enter or leave the system to maintain a constant temperature. → polytropic process. Astrophysical examples include the → collapse of a → protostar down the → Hayashi track, and the collapse of a star at the end of its life to become a → white dwarf.
Fr.: vent isotherme
A → stellar wind in which the gas is subject to only two forces: the inward directed gravity and the outward directed gradient of the gas pressure.
One of several nuclides having the same number of neutrons in their nuclei but differing in the number of protons.
Isotone, from → iso- + tone, from Gk tonos "strain, tone, mode," literally, "a stretching," akin to teinein "to stretch," cognate with Pers. tanidan "to spin, twist, weave" (Mid.Pers. tanitan; Av. tan- "to stretch, extend;" cf. Skt. tan- to spin, stretch;" tanoti "stretches," tantram "loom;" Gk. teinein "to stretch, pull tight;" L. tendere "to stretch; PIE base *ten- "to stretch;" Pers. târ "string," tân "thread," tur "fishing net, net, snare," and tâl "thread" (Borujerdi dialect) belong to this family; variants tanta "cobweb," tanadu, tafen, kartané, kârtané, kâtené, Pashtu tanistah "cobweb;" cf. Skt. tantu- "cobweb, thread, string").
izotop (#), hamjâ (#)
One of two or more atoms having the same number of protons in its nucleus, but a different number of neutrons and, therefore, a different mass.
Isotope, from → iso- + -tope, from Gk. topos "place."
Izotop, loan from Fr., as above. hamjâ, from ham- "together" → com- + jâ "place" (from Mid.Pers. giyag "place;" O.Pers. ā-vahana- "place, village;" Av. vah- "to dwell, stay," vanhaiti "he dwells, stays;" Skt. vásati "he dwells;" Gk. aesa (nukta) "to pass (the night);" Ossetic wat "room; bed; place;" Tokharian B wäs- "to stay, wait;" PIE base ues- "to stay, live, spend the night").
Fr.: fractionnement isotopique
A slight difference between the → abundances of → isotopes of the same → chemical element owing to → physical or → chemical → processes. It results in the → enrichment or → depletion of an isotope. Same as → isotopic fractionation.
Fr.: décalage isotopique
A displacement in the spectral lines due to the different isotopes of an element.
Of or relating to an → isotope.
Fr.: fractionnement isotopique
Same as → isotope fractionation.
Fr.: nombre isotopique
The difference between the number of neutrons in an isotope and the number of protons. Neutron excess.
Fr.: rapport isotopique
The relative abundances of two isotopes of a given chemical element, such as D/H (deuterium/hydrogen), (carbon) 12C/13C, and (uranium) 235U/238U.
spin-e izotopi (#), izospin (#)
Fr.: spin isotopique
Same as → isospin.
Any of molecular entities which differ in their isotopic composition but retain the same → chemical elements, e.g. H2O and HDO.
Any of → isomers having the same number of each isotopic atom but differing in their positions. For example, CH3CHDCH3 and CH3CH2CH2D are a pair of isotopomers.
Short for isotopic isomers.
izogard, hamsângard (#)
Having physical properties that do not vary with direction.
giti-ye izogard, ~ hamsângard (#)
Fr.: Univers isotrope
A Universe having observed properties that appear identical in every direction.
izogardi, hamsângardi (#)
The property by which physical properties are equal along all directions. → anisotropy.
Isotropy, noun of → isotropic.
1) borunây; 2) borunâyidan
Fr.: issue, question, problème
1a) A result or outcome of something.
M.E., from O.Fr. issue "a way out, a going out, exit; final event," from L. exire "to go out, go forth; become public; flow, pour forth," from → ex- "out," + ire "to go,"
Iterate "to do again, repeat," back-formation from iteration, from L. iterationem (nom. iteratio) "repetition," noun of action from iterare "to do again, repeat," from iterum "again, for the second time;" cf. Skt. itara- "the other (of the two), another."
Itaridan, from L. iter(um), Skt. itar(a-), as above, and Pers. dialects Kâšâni (Voništun) târ "the other;" Kurd. tir "the other" + -idan Pers. infinitive suffix.
A computational process involving a succession of approximations, which consists of repeating the operation by inputting the outcome of each preceding operation to improve the final result until a desired accuracy is achieved. Compare → repetition.
Verbal noun of → iterate.
Fr.: méthode itérative
A method of computation in mathematics using → iteration.