1) The mental process in which an element or quality is separated from a
total object. Also the result of this process.
vâžireš-e âhanješ (#)
Fr.: réaction d'abstraction
Chemistry: A bimolecular chemical reaction that involves removal of an atom or ion from a molecule. For example, hydrogen abstraction from methane: CH4 + Cl → CH3 + HCl.
→ abstraction; → reaction.
žireš, koneš (#)
1) The process or state of acting or of being active.
Action, from O.Fr. action, from L. actionem, from agere "to do," → act.
Žireš, verbal noun from žir stem of žiridan "to act;" → act. Koneš, noun from kardan "to do, to make," Mid.Pers. kardan, O.Pers./Av. kar- "to do, make, build," Av. kərənaoiti "makes," cf. Skt. kr- "to do, to make," krnoti "makes," karma "act, deed;" PIE base kwer- "to do, to make."
action at a distance
žireš az dur
Fr.: action à distance
The instantaneous action of a body on another body independently of the distance separating them. The description of → gravity by → Newton's law and → electrostatics by → Coulomb's law are examples of action at a distance. According to Newton, → gravitation acts directly and instantaneously between two objects. For example, if the Sun should suddenly break apart, the Earth's orbit would be affected instantaneously. However, action at a distance violates the → principle of relativistic causality. According to → general relativity, gravitational effects travel at the → speed of light. For modern physics there is no instantaneous action at a distance.
Fr.: variable d'action
The time integral associated with the evolution of a physical system in the phase space.
angle of refraction
zâviye-yé šekast (#)
Fr.: angle de réfraction
The angle between the direction in which a ray is refracted and the normal to the refracting surface.
→ angle; → refraction.
Fr.: réfraction astronomique
The → angular → displacement of a point on the → celestial sphere due to the Earth's → atmospheric refraction.
→ astronomical; → refraction.
Fr.: réfraction atmosphérique
The shift in apparent direction of a celestial object caused by the bending of light while passing through the Earth's atmosphere. Since the density of the atmosphere decreases with altitude, the starlight will bend more as it continues down through the atmosphere. As a result, a star will appear higher in the sky than its true direction.
→ atmospheric; → refraction.
The act or capability of attracting. A physical force (gravitational, electric, magnetic, etc.) exerted by material bodies.
Attraction, n. from → attract.
žireš-e muyiné, muyinegi
The ability of a → liquid to → flow in a → narrow space, such as a thin → tube, without the assistance of, and in opposition to, external forces like → gravity. Also called → capillarity. It occurs because of intermolecular → attractive forces between the liquid and solid surrounding surfaces. If the diameter of the tube is sufficiently small, then the combination of → surface tension (which is caused by → cohesion within the liquid) and → adhesion (between the liquid and the → container) acts to lift the liquid. The capillarity of the liquid is high when adhesion is greater than cohesion. For example, water in a thin glass tube has strong → adhesive forces due to the hydrogen bonds that form between the water molecules and the oxygen atoms in the glass wall (made of → silica, SiO2). In contrast, mercury is characterized by stronger cohesion, and hence its capillarity is much lower.
center of attraction
Fr.: centre d'attraction
A point toward which a force on a body is always directed.
→ center; → attraction.
vâžireš-e zanjiri, vâkoneš-e ~
Fr.: réaction en chaîne
A succession of → nuclear fissions when the neutrons released by previous fissions produce other nuclear fissions which themselves cause other reactions and the reactions goes on increasing exponentially.
vâžireš-e šimiyâyi, vâkoneš-e ~
Fr.: réaction chimique
A → change or → transformation in which a → substance → decomposes, → combines with other → substances, or interchanges constituents with other substances.
Fr.: fraction d'entiers
A fraction written as a/b where a and b are → positive → integers, as opposed to a → decimal fraction; for example, 5/7. Common fractions are sometimes also called → vulgar fractions.
1) The act of compacting or the state of being compacted.
Fr.: fraction complexe
A fraction in which the → numerator or → denominator, or both, contain fractions. For example (3/5)/(6/7). Also called → compound fraction.
Fr.: fraction composée
Same as → complex fraction.
Fr.: fraction continue
In mathematics, a fraction whose numerator is an integer and whose denominator is an integer plus a fraction whose numerator is an integer and whose denominator is an integer plus a fraction and so on.
An act or instance of contracting; the quality or state of being contracted.
Verbal noun of → contract.
corotating interaction region (CIR)
nâhiye-ye andaržireš-e hamcarxandé
Fr.: région d'interaction en corotation
A spiral-shaped density enhancement formed around a star when fast stellar winds collide with slower material. This large-scale wind structure can extend from the stellar surface to possibly several tens of stellar radii. The CIRs can be produced by intensity irregularities at the stellar surface, such as dark and bright spots, magnetic loops and fields, or non-radial pulsations. The surface intensity variations alter the radiative wind acceleration locally, which creates streams of faster and slower wind material. CIRs are responsible for the → discrete absorption components seen in some ultraviolet → resonance lines of → hot stars (S. R. Cranmer & S. P. Owocki, 1996, ApJ 462, 469).
→ corotate; → interaction; → region.