First Point of Aries
noqte-ye âqâz-e barré (#)
Fr.: premier point de Bélier
One of the two points on the celestial sphere where the ecliptic and the celestial equator crossed one another at → vernal equinox several thousands years ago.
First Point of Libra
noqte-ye âqâz-e tarâzu (#)
Fr.: permier point de Balance
One of the two points on the celestial sphere where the ecliptic and the celestial equator crossed one another at → autumnal equinox several thousands years ago. Because of → precession, this equinoctial point no longer lies in Libra but in neighboring Virgo.
Fr.: premier quartier
A → lunar phase that occurs in the middle of the interval between the → new Moon and the → full Moon, when half of the Moon's disk is illuminated. At first quarter, the Moon is situated at 90° east of the Sun.
Fr.: première étoile
A member of the → Population III → massive stars that formed some 500 Myr after the → Big Bang. First stars had a simple chemical composition consisting only of H, He, and traces of 7Li and were very short-lived. They are the most likely sources of → reionization of the Universe, which put an end to the → Cosmic Dark Age.
first-order differential equation
hamugeš-e degarsâne-yi-ye râye-ye naxost
Fr.: équation différentielle du premier ordre
first-order logic (FOL)
guyik-e farâsani-ye râye-ye naxost, ~ farâsanhâ-ye ~ ~
Fr.: logique des prédicats du premier ordre
A system of → formal logic that is an extension of → propositional logic. It is also known as → first-order predicate calculus and → predicate logic. FOL eliminates deficiencies of propositional logic by: representing → objects (their properties, relations and statements about them), introducing → variables, and introducing → quantifiers.
first-order partial derivative
vâxane-ye pâri-ye râye-ye naxost
Fr.: dérivée partielle du premier degré
first-order predicate calculus
afmârik-e farâsani-ye râye-ye naxost
Fr.: cacul des prédicats du premier ordre
Same as → first-order logic.
binâb-e râye-ye naxost
Fr.: spectre du premier ordre
An optical spectrum, produced by a diffraction grating, in which the difference in path length of light from adjacent slits is one wavelength.
A limbless cold-blooded vertebrate animal with gills and fins living wholly in water (OxfordDictionaries.com).
M.E. fis(c)h, fyssh, O.E. fisc; cognate with Du. vis, Ger. Fisch, O.Norse fiskr, Goth. fisks; akin to L. piscis; PIE root *pisk- "a fish."
Mâhi "fish," from Mid.Pers. mâhik; Av. masya-; cf. Skt. matsya-, Pali maccha-.
šekâftpazir (#), šekâftani (#)
Any material that is capable of undergoing → nuclear fission by → thermal neutrons. The three primary fissile materials are uranium-233, uranium-235, and plutonium-239. Although sometimes used as a synonym for → fissionable material, this term has acquired a more restricted meaning.
From L. fissilis, from fiss(us), + -illis a suffix of adjectives expressing capability, susceptibility, liability, aptitude, etc.
Šekâftani, from šekâft, → fission + -i a suffix expressing capability, aptitude, etc.
Fr.: isotope fissile
An isotope that is capable of undergoing nuclear fission after capturing either fast neutron or thermal neutron. Typical fissionable isotopes: 238U, 240Pu, but also 235U, 233U, 239Pu, 241Pu
1) The act or process of splitting or breaking into parts.
Fission, from L. fissionem "a breaking up, cleaving," from root of findere "to split."
Šekâft, stem of šekâftan "to split, break, tear," akin to kaftan, kâftan "to split; to dig," Parthian Mid.Pers. q'f- "to split;" Sogdian kβ "to split;" Chorasmian kf- "to split, be split;" Proto-Iranian *kap-, *kaf- "to split."
farâvardehâ-ye šekâft (#)
Fr.: produits de fission
Nuclides generated by the fission of higher mass elements or by subsequent radioactive decay of nuclides directly generated by fission.
The material that can be fissioned by fast neutrons, such as uranium-238. Commonly used as a synonym for → fissile material.
1) saz kardan; 2) saz
Fr.: 1) ajuster; 2) ajustement
1) (v.) To pass a mathematical line or curve through data points.
From M.E. fitten; akin to M.Du. vitten "to befit."
Saz, from sazidan "to suit, fit, be worthy," sazâ "suitable, agreeing with, congruous, deserving of," Mid.Pers. sacitan/sazidan "to fit," sazešn "fitness," sazâg "fitting, worth;" Av. 1sak- "to understand or know a thing; to mark;" cf. Skt. śak- "to be able, powerful" śakta- "able, competent," śakti- "ability, power;" alternatively from Av. 2sak- "to go by, pass, pass away; to be up or over (of time)."
The process or instance of adapting a mathematical curve to data points.
Verbal form of → fit.
irang-e saz-kard, ~ saz
Fr.: erreur d'ajustement
The discrepancy between the mathematical curve and data points. → fit.
A cardinal number whose symbol is 5, V, or
Five, from O.E. fif, from P.Gmc. *fimfe (cf. O.S. fif, O.H.G. funf), from PIE *penkwe "five;" cognate with Pers. panj, as below.
Panj, from Mid.Pers. panj; Av. panca; cf. Skt. páñca; Gk. pente; L. quinque; E. five, as above.
Fr.: système à cinq couleurs
A photometric system which uses five filters, from ultraviolet to the red part of the visual spectrum: U, B, V, R and I.