lake-ye zard (#)
A small depression, approximately 1.5 millimeters in diameter, at the back of the → retina. It forms the area of the most acute vision.
Contraction of fovea centralis, from L. fovea "small pit," of unknown origin.
A geometrical or physical structure that repeats itself or nearly repeats itself on many different scales of magnification.
Fr.: cosmologie fractale
The postulate that the concentrations of matter in the Universe follow a → fractal structure over a wide range of scales.
Fr.: structure fractale
A → hierarchial structure that can be likened to fractals.
A rational number of the form a/b where a is called the numerator and b is called the denominator.
From L.L. fractionem (nom. fractio) "a breaking in pieces," from frangere "to break," from PIE base *bhreg- "to break" (cf. Goth. brikan, O.E. brecan "to break;" Lith. brasketi "crash, crack").
Barxé, from barx "lot, portion," variant bahr, from Mid.Pers. bahr "lot, share, portion," Av. baxəδra- "portion."
Fr.: fractionnaire, fractionné, partiel
1) Math.: Pertaining to fractions; constituting a fraction.
fractional sky coverage
pušeš-e barxe-yi-ye âsmân
Fr.: couverture partielle du ciel
The portion of the 4π → steradians of the sky that a radiotelescope can observe from a given location on Earth over a 24-hour time interval.
1) To break something up into smaller parts.
From → fraction + -ate a suffix forming verbs or nouns, from L. -atus, -ata, -atum.
Barxândan, from barx, barxé, → fraction, + -ândan suffix of transitive verbs.
1) Any of various methods of separating the components of a mixture into
fractions of different properties.
Verbal noun from → fractionate.
1) latté (#), latt (#), pâré (#); 2) latpâr šodan (#); 3) latpâridan
Fr.: 1) fragment; 2) se fragmenter; 3) fragmenter
1) (n.) A part broken off or detached.
From L. fragmentum, from frangere "to break."
1) Latté, lat, variant laxt, laxté "piece, part;"
pâré "piece, part, portion, fragment;" Mid.Pers. pârag
"piece, part, portion; gift, offering, bribe;" Av. pāra- "debt," from
par- "to remunerate, equalize; to condemn;"
PIE *per- "to sell, hand over, distribute; to assigne;" cf. L. pars
"part, piece, side, share,"
portio "share, portion;" Gk. peprotai "it has been granted;"
Skt. purti- "reward;"
Hitt. pars-, parsiya- "to break, crumble."
Generally, the process of breaking up into smaller parts. In particular, the splitting of a large molecular cloud into smaller, denser clumps. → cloud fragmentation.
From → fragmenta + -ation, a combination of -ate and -ion, used to form nouns from stems in -ate.
Latpâreš, verbal noun from latpâridan, → fragment.
Fr.: processus de fragmentation
1) cârcub (#); 2), 3) tasvirak
Fr.: 1) cadre; 2), 3) image
1) A border or case for enclosing a picture, mirror, etc.; a structure for admitting or
Frame, from M.E. verb framen "to prepare (timber)," from O.E. framian "to avail, profit."; cf. O.H.G. (gi)framon "to do."
1) Cârcub "frame," from câr, contraction of cahâr "four" (→ four) + cub "stick, satff, beam," Mid.Pers. côp "wood, stick." 2) Tasvirak from Ar. tasvir "image" + -ak suffix of relation and similarity (as in poštak, dastak, nâxonak), → fibril.
kerre-ye cârcub, cârcub-kerré
Fr.: entraînement des repères, effet Lense-Thirring
The alteration in the → free fall motion of a test → mass in the presence of a massive → rotating object, as compared to the identical case of a non-rotating object. This dragging of → inertial frames is predicted by → general relativity. Also called → Lense-Thirring effect.
Fr.: fréquence image
The number of times per second that the frame is scanned in television. Also known as picture frequency.
frame of reference
Fr.: système de référence
A set of axes to which positions and motions in a system can be referred.
The process of adjusting a television picture to a desired position in the direction of progression.
Cârcubeš, verbal noun of cârcubidan, from cârcub→ frame.
An extremely rare radioactive chemical element; symbol Fr. Atomic number 87; atomic weight of most stable isotope 223; melting point about 27°C; boiling point about 677°C. Its most stable isotope (half-life about 22 minutes) occurs naturally, to a very limited extent, in uranium minerals. More than 30 other isotopes of francium are known; some are prepared by bombarding thorium with protons, deuterons, or alpha particles.
From France, where the French physicist Marguerite Perey (1919-1975) discovered it in 1939 in the alpha particle decay of actinium.
Fr.: raie de Fraunhofer
One of many absorption lines and bands in the spectrum of the Sun. The most prominent features are labeled with capital letters A to K, starting at the red end. The A and B bands are now known to be caused by absorption in Earth's atmosphere, while the rest are due to absorption in the Sun's → photosphere. C and F are now better known as H-alpha and H-beta (→ Balmer series); the → D lines are of sodium, the → H and K lines of calcium, and the G band of neutral iron and the interstellar → CH (methylidine) molecule.
Named after Joseph von Fraunhofer (1787-1826), German optician and physicist, who discovered these lines in 1814; → line.
Fr.: réfracteur de Fraunhofer
The first modern refracting telescope which had an outstanding quality. It was built in 1824 by Fraunhofer for the Russian Imperial Observatory in Dorpat, now Tartu in Estonia. It had a 23-cm → achromatic lens and a German-type → equatorial mounting driven by a clockwork. Wilhelm Struve (1793-1864) used the refractor to observe many → visual binaries, and attempted to measure the distances of stars through their visual → parallaxes. He also obtaibned accurate values for the diameters of the → Galilean satellites of → Jupiter.
Named after Joseph von Fraunhofer (1787-1826), German optician and physicist; → refractor.