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president farneštgâr Fr.: président 1) The highest executive officer of a modern republic, as the Chief Executive of
the United States (often initial capital letter). Farneštgâr, from farnešt, present stem of farneštidan, → preside, + agent noun suffix -gâr, → -or, on the model of âmuzgâr "teacher." |
presolar piš-xoršidi Fr.: pré-solaire Of or relating to an epoch earlier than the formation of the Sun. |
presolar grain dâne-ye piš-xoršidi Fr.: grain pré-solaire A → refractory → nanoparticle embedded in → meteorites and → interplanetary dust particles whose → isotopic ratios suggest formation earlier than the Solar System. |
Press-Schechter formalism disegerâyi-ye Press-Schechter Fr.: formalisme de Press-Schechter A mathematical analysis, based on → self-similarity, used to predict the → mass function of spherically collapsing → dark matter halos. The formalism assumes that the fraction of mass in halos more massive than M is related to the fraction of the volume in which the smoothed initial density field is above some threshold δcρ, where ρ is the average density of the Universe, with the volume encompassing a mass larger than M. A variety of smoothing → window functions and thresholds have been argued, but the most common is a top-hat window in real space and δc≅ 1.69. The Press-Schechter formalism provides a relatively good fit to the results of numerical simulations in cold dark matter theories. First described by William H. Press and Paul Schechter's paper (1974, ApJ 187, 425); → formalism. |
pressure fešâr (#) Fr.: pression The force per unit area. M.E., from O.Fr. pressure, from L. pressura "action of pressing," from pressus, p.p. of premere "to press, compress." Fešâr "squeezing, constriction, compression," verb fešordan, fešârdan "to press, squeeze;" phonetic variants Lori xošâr, Aftari xešâr, Qazvini, Qomi xošâl; cf. Khotanese ssarr- "to exhilarate;" loaned in Arm. ôšarak, in Ar. afšaraj "juice." |
pressure broadening pahneš-e fešâri Fr.: élargissement par pression A broadening of spectral lines caused mainly by the stellar atmospheric density and the surface gravity of the star. The line strength of a spectral line depends on the number of atoms in the star's atmosphere capable of absorbing the wavelength in question. For a given temperature, the more atoms there are, the stronger and broader the spectral line appears. Denser stars with higher surface gravity will exhibit greater pressure broadening of spectral lines. → pressure; → broadening. |
pressure gradient zine-ye fešâr Fr.: gradient de pression The pressure difference between two adjacent regions of a fluid that results in a force being exerted from the high pressure region toward the low pressure region. |
pressure gradient force niru-ye zine-ye fešâr Fr.: force du gradient de pression A force resulting from → pressure gradient that is directed from high to low pressure. |
pressure ionization yoneš-e fešâri Fr.: ionisation par pression A physical state of dense matter in which the electrostatic field of one atom should influence a neighboring atom and hence disturb atomic levels. In extreme case, such as white dwarfs, electron clouds practically rub and electrons are ionized off the parent atoms. → pressure; → ionization. |
pressure mode tarz-e fešâr, mod-e ~ Fr.: mode pression Same as → p mode |
pressure scale height bolandi-ye marpel-e fešâr Fr.: hauteur d'échelle de pression A basic ingredient of the → mixing length theory that scales with the → mixing length. It is defined by the relation: HP = -dr/dln P = -Pdr/dP , where r is the height and P the pressure. See also → scale height. |
previous pišin (#) Fr.: précédent Occurring before something else in time or order. From L. praevius "leading the way," from prae-, → pre- + via "way." Pišin, from piš "before," → pre-. |
previously pišâné Fr.: précédemment, auparavant Coming or occurring before something else; prior. |
Prevost's law of exchanges qânun-e gahuleš-e Prévost Fr.: loi des échanges de Prévost A statement concerned with thermodynamic heat exchange, according to which bodies in → thermal equilibrium are simultaneously absorbing and emitting radiant energy. A body radiates in the same way whether other bodies are present or not. Also called Prevost's theory of exchanges. Named after Pierre Prévost (1751-1839), a Swiss philosopher and physicist, who, in 1791, put forward the statement; → law; → exchange. |
prey 1) cavidan; 2) cavâk Fr.: 1) faire sa proie de; 2) proie 1) To seize and devour prey, as an animal does. M.E. preye, from O.Fr. preie, from L. praeda "booty, plunder, game hunted;" ultimately from prehendere "to grasp, seize." 1) Cavidan, related to Khotanese cev- "to get, seize,"
Ossetic cævyn, cavd "to hit, to strike," Pers. câpidan
"to plunder," cafsidan, caspidan "to stick; to plunder;" Proto-Ir.
*cap- "to seize." |
prey animal jânevar-e cavâk Fr.: animal proie An animal that is hunted and killed by a → predator as food. |
Priestley's rings halqehâ-ye Priestley Fr.: anneaux de Priestley The concentric colored rings formed by an electrical → spark when a → discharge takes place on a metallic plate. Joseph Priestley (1733-1804), English chemist, author, and clergyman; → ring. |
primary naxostân Fr.: primaire, principal 1) First or highest in rank or importance; chief; principal. M.E., from L. primarius "of the first rank, principal," from primus "first." Naxostân, from naxost, from Mid.Pers. naxust "the first," Parthian Mid.Pers. nxwšt, from naxu, Manichean Parthian nwx "beginning" + -ist superlative suffix, Av. -išta-, cf. Skt. -istha-, Gk. -istos, O.H.G. -isto, -osto, O.E. -st, -est, -ost. |
primary body jesm-e naxostân Fr.: corps principal The body that is being orbited; such as the → Sun in the → solar system. As regards → multiple star systems, the most massive, or → primary star. See also: → secondary body. |
primary cell pil-e noxostân Fr.: A → cell in which the electrochemical action producing the current is not normally reversible. Such a cell cannot be recharged by an electric current. → secondary cell. |
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