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Bose-Einstein condensation (BEC) cagâleš-e Bose-Einstein Fr.: condensation de Bose-Einstein A → quantum phase transition during which the → bosons constituting a sufficiently cooled boson gas are all clustered in the → ground energy state. The phase transition results in a → Bose-Einstein condensate. This phenomenon occurs when the temperature becomes smaller than a critical value given by: T_{c} = (2πħ^{2} / km)(n / 2.612)^{2/3}, where m is mass of each boson, ħ is the → reduced Planck's constant, k is → Boltzmann's constant, and n is the particle number density. When T ≤ T_{c}, the → de Broglie wavelength of bosons becomes comparable to the distance between bosons. → boson; → Einstein; → condensation. |
Bose-Einstein distribution vâbâžeš-e Bose-Einstein Fr.: distribution de Bose-Einstein For a → population of independent → bosons, a function that specifies the number of particles in each of the allowed → energy states. → boson; → Einstein; → distribution. |
Bose-Einstein statistics âmâr-e Bose-Einstein (#) Fr.: statistique de Bose-Einstein Same as → Bose-Einstein distribution. → boson; → Einstein; → statistics. |
boson boson (#) Fr.: boson Any of a class of particles (such as the → photon, → pion, or → alpha particle) that have zero or integral → spin and do not obey the → Pauli exclusion principle. The energy distribution of bosons is described by → Bose-Einstein statistics. See also: → gauge boson, → Higgs boson, → W boson, → Z boson, → intermediate boson. Boson, in honor of the Indian-American physicist Satyendra Nath Bose (1894-1974). |
botany giyâhšenâsi (#) Fr.: botanique The branch of → biology that deals with → plants. From botanic, from Fr. botanique, M.L. botanicus, from Gk. botanikos "of herbs," from botane "herb, grass, pasture." |
Botein (δ Ari) Boteyn (#) Fr.: Botein A dim, red star in the constellation → Aries; a → giant of → spectral type K2 III at a distance of 168 light-years. Botein, from Ar. Al-Butain "the little belly." Boteyn, from Ar. Al-Butain. |
bottle botri (#) Fr.: bouteille A portable vessel for liquids, typically cylindrical and often of glass or plastic with a narrow neck that can be closed. → magnetic bottle, → Leyden jar. From O.Fr. bo(u)teille, from L.L. butticula diminutive of L. buttis "a cask." Botri, loan from Fr. bouteille or E. bottle, as above. |
bottom tah (#), pâyin (#) Fr.: bas, fond 1) The lowest or deepest part of anything, as distinguished from the
→ top. The under or lower side; underside.
→ bottom-up structure formation. M.E. botme; O.E. botm, bodan "ground, soil, lowest part" (cf. O.Fris. boden "soil," O.N. botn, O.H.G. bodam, Ger. Boden "ground, earth, soil"), akin to Pers. bon "basis; root; foundation; bottom;" Mid.Pers. bun "root; foundation; beginning;" Av. būna- "base, depth" (Skt. bundha-, budhná- "base, bottom," Pali bunda- "root of tree;" Gk. pythmen "foundation;" L. fundus "bottom, piece of land, farm," O.Ir. bond "sole of the foot"). Tah "bottom; end"
(Mid.Pers. tah "bottom." The origin of this term is not clear.
It may be related to PIE *tenegos "water bottom;" cf.
Gk. tenagos "bottom, swamp," Latvian tigas, from *tingas, from
*tenegos "depth"). |
bottom-up structure formation diseš-e sâxtâr az pâyin bé
bâlâ Fr.: formation des structures du bas vers le haut A → structure formation scenario in which small galaxies form first, and larger structures are then formed in due course. Contrary to → top-down structure formation. |
bound 1) bandidé; 2) karân Fr.: lié; lien 1) (adj.) Tied, confined by bonds. → bound cluster,
→ bound charge, → bound system. |
bound charge bâr-e bandidé Fr.: charge liée Any electric charge which is bound to an atom or molecule, in contrast to free charge, such as metallic conduction electrons, which is not. Also known as → polarization charge. |
bound cluster xuše-ye bandidé Fr.: amas lié A cluster of astronomical objects, such as stars or galaxies, held together by their mutual gravitational attraction. → bound system. |
bound occurrence roxdâd-e bandidé Fr.: occurrence liée Any → occurrence of a → variable x in an x-bound part of a → wff. → bound; → occurrence. |
bound orbit madâr-e bandidé Fr.: orbite liée The orbit described by an object around a central gravitational force in a system whose total energy is negative. An elliptical orbit. |
bound system râžmân-e bandidé Fr.: système lié A system composed of several material bodies the total energy of which (the sum of kinetic and potential energies) is negative, e.g. a → bound cluster. |
bound-bound transition gozareš-e bandidé-bandidé Fr.: transition liée-liée A transition between two energy levels of an electron bound to a nucleus. The electron remains tied to the nucleus before and after the transition. → bound-free transition; → free-free emission. Bound, p.p. of → bind; → transition. |
bound-free transition gozareš-e bandidé-âzâd Fr.: transition liée-libre A transition in which a bound electron is liberated. → free-bound emission; → free-free emission. |
boundary karân (#) Fr.: limite, bord 1) General:
Something that indicates a border or limit; the border or limit so indicated. From Fr., from O.Fr. bodne, from M.L. bodina, butina "boundary, boundary marker." Karân, karâné, kenâr from Mid.Pers. karânag, Av. karana- "boundary." |
boundary conditions butârhâ-ye karân, ~ karâni Fr.: conditions à la limite 1) Math: Restriction on the limits of applicability of an equation.
In a differential equation, conditions that allow to fix the constant
of integration and reach a unique solution. The number of boundary conditions
necessary to determine a solution matches the order of the equation. |
boundary effect oskar-e karân Fr.: effet de bords An effect that forbids or invalidate locally the use of an idealized model of a system in which one or several of its dimensions are supposed to be infinite. |
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