Fr.: calcul opérationnel
A method of mathematical analysis which in many cases makes it possible to reduce the study of differential operators, pseudo-differential operators and certain types of integral operators, and the solution of equations containing them, to an examination of simpler algebraic problems. It is also known as operational analysis.
In the philosophy of science, the view that → concepts are defined in terms of measuring operations which determine their applicability. Same as operationism.
Fr.: aberration optique
Fr.: migration orbitale
Theoretical prediction according to which a → giant planet, formed in the outer regions of a → protoplanetary disk, could migrate inward by losing → energy and → angular momentum as the result of → gravitational interactions with the remnants of the disk. This orbital migration could explain the presence of giant gaseous Jupiter-like planets (→ hot Jupiters) very close to their host stars.
Fr.: rapport de partition
1) Depreciation; a lessening in worth, quality, etc.
Verbal noun of → pejorate.
The process by which atomic nuclei are broken apart into their constituent protons and neutrons by the impact of high energy gamma photons. Photodisintegration takes place during the core collapse phase of a → Type II supernova explosion.
A process going on in a molecular cloud surface whereby the surface material ionized by ultraviolet photons of neighboring stars is dissipated.
kabizeš-e šidsanjik, ~ nursanjik
Fr.: calibration photométrique
A calibration which converts the measured relative magnitudes into an absolute photometry.
halâzân-e fiziki, roxgard-e ~
Fr.: libration physique
A real periodic variation in the rotation rate of a celestial object, as distinct from a → geometrical libration. In particular, slight oscillations in the → Moon's rotation caused by the → gravitational attraction of the Earth on the → equatorial bulge of the Moon's near side. The Moon's physical libration is about 0.03° in longitude and about 0.04° in latitude.
plane of vibration
Fr.: plan de vibration
In a → linearly polarized light, a plane perpendicular to the → plane of polarization and containing the direction of propagation of light. It is also the plane containing the direction of propagation and the electric vector (E) of the electromagnetic light wave.
Fr.: aberration planétaire
The difference between the true position of a planet and its apparent position, due to the time required for light to travel the distance from the planet to Earth. Correction for planetary aberration is necessary in determining orbits.
Fr.: rapport de Pogson
Fr.: migration radiale
The process whereby a → disk star changes its → galactocentric distance. Radial migration involves → angular momentum transfer, resulting from → resonances created by transient → density waves such as → bars or → spiral arms in → galactic disks. According to → galactic dynamics models, → churning is the main cause of radial migration. Radial migration of stars plays an important role in shaping the properties of galactic disks.
Fr.: accélération radiative
The acceleration imparted to matter by → radiation pressure.
radius of gyration
Same as → Larmor radius.
Math.: The quotient of two quantities arrived at by dividing one by the other.
From L. ratio "reckoning, calculation," also "reason," from rat-,
p.p. stem of reri "to reckon, calculate," also "think," → reason.
Vâbar, on the model of Fr. rapport "bringing back," as above, from vâ- prefix meaning "back to the original place, again," → re-, + bar present stem of bordan "to carry, lead" (Mid.Pers. burdan, O.Pers./Av. bar- "to bear, carry," barəθre "to bear (infinitive)," Skt. bharati "he carries," Gk. pherein, L. fero "to carry;" PIE base *bher- "to carry").
1) râyani, râyanvâr; 2) xeradâné, xeradmandâné; 3) vâbari
1) Having or exercising the ability to → reason.
M.E. racional, from O.Fr. racionel, from L. rationalis "of or belonging to reason, reasonable," from ratio (genitive rationis) "reckoning, calculation, reason," from rat-, pp. stem of reri "to reckon, calculate; consider, think."
1) Râyani, of or pertaining to râyan, → reason.
Fr.: nombre rationnel
Any number that can be expressed as a ratio of two integers, providing the second number is not zero.
Fr.: raisonnement, exposé raisonné
1) The fundamental reason or reasons serving to account for something.
L. neuter of rationalis.