Fr.: mouvement de rotation
Of a → rigid body, a motion in which there are always two points of the body which remain motionless.
Fr.: période de rotation
Fr.: transition rotationnelle
A slight change in the energy level of a molecule due to the rotation of its constituent atoms about their center of mass.
Fr.: vitesse de rotation
carxandé (#), carxânandé (#)
A device that rotates or causes rotation.
Agent noun from → rotate.
A rotating part of an electrical apparatus, e.g. the armature of a generator,
or of a mechanical device.
Carxâ agent noun of carxidan, → rotate.
Fr.: ligne, rangée
CCD detector: Series of pixels arranged along a line. → column
O.E. ræw "a row, line;" cf. Du. rij "row;" O.H.G. rihan "to thread," riga "line;" Ger. Reihe "row, line, series."
Raj "line, row," variants raž, rak, râk, rezg (Lori), ris, risé, radé, rasté, râsté, related to râst "right, true; just, upright, straight;" Mid.Pers. râst "true, straight, direct;" Soghdian rəšt "right;" O.Pers. rāsta- "straight, true," rās- "to be right, straight, true;" Av. rāz- "to direct, put in line, set," razan- "order;" cf. Skt. raj- "to direct, stretch," rjuyant- "walking straight;" Gk. orektos "stretched out;" L. regere "to lead straight, guide, rule," p.p. rectus "right, straight;" PIE base *reg- "move in a straight line," hence, "to direct, rule."
Fr.: critère de Roxburgh
An integral constraint used to quantify the uncertainty on the extent of → convective overshooting and its effect on models of stars.
Roxburgh, I. 1989, A&A, 211, 361; → criterion.
RR Lyrae star
setâre-ye RR Cang
Fr.: étoile RR Lyrae
A member of a large class of → pulsating stars of type A2-F6 with periods less than 1 day. They are similar to → Cepheids, except that their periods are much shorter and are less luminous. RR Lyrae stars belong to → Population II and are often found in → globular clusters (hence one of their older names cluster variables) or elsewhere in the → galactic halo. They are used as distance indicators (→ standard candle) out to more than 200 kpc.
A metallic chemical element; symbol Rb. Atomic number 37; atomic weight 85.4678; melting point 38.89°C; boiling point 686°C; specific gravity 1.53 at 20°C. It was discovered in the mineral lepidolite by the German chemist Robert Wilhelm Bunsen and the German physicist Gustav-Robert Kirchoff in 1861. Bunsen isolated rubidium in 1863.
From L. rubidus "deep red," because of the two "deep red lines" in its spectra.
yâqut (#), yâkand (#)
Red form of corundum, Al2O3, which owes its color to traces of chromium. Used in laser as a gem stone.
M.E. rubi, from O.Fr. rubi, from M.L. rubinus lapis "red stone," from L. rubeus "red," related to ruber→ red.
Yâqut, yâkand related to Gk. hyakinthos "hyacinth," probably ult. from a non-I.E. Mediterranean language.
Fr.: Tables rudolphines
A set of astronomical tables created in 1627 by Johannes Kepler (1571-1630) based on observations by Tycho Brahe (1546-1601). These tables allowed Kepler to derive the three laws of planetary motions bearing his name (→ Kelpler's laws). These are the first tables in which → atmospheric refraction has been taken into account. They overruled the → Prutenic Tables.
From the L. title Tabulae Rudolphinae, in memory of Rudolf II (1552-1612), king of Hungary and Bohemia, and Holy Roman Emperor; → table.
Fr.: méthode de Ruffini-Horner
A method for finding the value of a → polynomial given by a real number and deriving its → roots. It consists essentially of factoring the polynomial in a nested form. Also known as → nested multiplication.
Named after Paolo Ruffini (1765-1822) and William Horner (1786-1837), who independently elaborated the method; → method.
Fr.: bobine de Ruhmkorff
An → induction coil which was a forerunner of today's automobile ignition coil. It consists of two coils wound on a single → iron core, and uses an → alternating current produced by a break-wheel to induce a high-voltage current in the secondary coil.
After Heinrich Daniel Ruhmkorff (1803-1877), a German-born instrument maker, who settled in Paris in 1819 for the rest of his life; → coil.
1) A law or regulation that governs behaviors, actions, or operations.
→ Arnett's rule, → commutation rule,
→ Fleming's rule, → Hund's rule,
→ left-hand rule, → Maxwell's rule,
→ right-hand rule, → rigorous selection rule,
→ selection rule, and
→ Trouton's rule.
M.E. riule, reule, from O.Fr. riule, from L. regula "straight stick, bar, ruler," related to regere "to rule, straighten, guide;" cognate with Pers. râst "right, straight," razan "rule," as below.
Razan from Av. razan "rule, order," from rāz- "to direct, put in line, set," rasman- "the lines or files of the army;" O.Pers. rāsta- "straight, true," rās- "to be right, straight, true;" Mid.Pers. râst "true, straight, direct;" Soghdian rəšt "right," rây-, râyênitan "to arrange;" Mod.Pers. râst "right, true; just, upright, straight;" raj "line, row," variants raž, rak, râk, rezg (Lori), radé, râdé "line, rule, row," rasté, râsté "row, a market with regular ranges of shops;" ris, risé "straight;" cf. Skt. raj- "to direct, stretch," rjuyant- "walking straight;" Gk. orektos "stretched out;" L. regere "to lead straight, guide, rule," p.p. rectus "right, straight;" PIE base *reg- "move in a straight line," hence, "to direct, rule."
rule of decision
Fr.: régle de décision
rule of three
Fr.: règle de trois
Te method of finding the fourth term in a proportion when three terms are given.
Fr.: réseau à traits
A → diffraction grating with a series of grooves that have been ruled on a reflective surface with a diamond tool mounted on a ruling machine. Ruled gratings may have triangular or trapezoidal groove profiles, whereas → holographic gratings usually have sinusoidal groove profiles.
ruye-ye xatt sâxté
Fr.: surface réglée
A surface, such as a cylinder or cone, that can be generated by moving a straight line.
Ruled, p.p. of rule; → surface.
Ruyé, → surface; xatt sâxté "built, formed by a line," from xatt→ line; sâxté, p.p. of sâxtan "to build, make, fashion; to adapt, adjust, be fit" (from Mid.Pers. sâxtan, sâz-, Manichean Parthian s'c'dn "to prepare, to form;" Av. sak- "to understand, to mark," sâcaya- (causative) "to teach").
kapal (#), sorin (#)
The hind part of the body of an animal, as the hindquarters of a quadruped or sacral region of a bird (Dictionary.com).
M.E. rumpe, from Scandinavian; compare Dan., Norw. Swed. rumpe rumpa "tail;" cognate with Ger. Rumpf "body, trunk."
Kapal, maybe from Ar. kafal.