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side bar (#), pahku (#), kenâr (#) Fr.: côté 1) A line segment that forms part of the perimeter of a plane geometric figure. M.E., from O.E. side "flanks of a person, the long part of anything;" cf. O.S. sida, O.N. sitha, M.Du. side, O.H.G. sita, Ger. Seite. Bar "side; breadth; breast,"
variant var; Mid.Pers. var "breast;"
Av. vouru "wide, broad, extended" (vourucašāni- "looking far"),
related to varah- "breast;" cf. Skt. urú- "wide, broad,"
úras- "breast;" Gk. eurus "wide, broad;"
PIE base uer-, ueru-s "wide, broad." |
side lobe lap-e kenâri Fr.: lobe secondaire 1) In → radio astronomy,
smaller amounts of gain found either side of the main lobe. |
sideband bând-e kenâri, kenâr-bând Fr.: bande latérale Either of the two bands of frequencies, one just above (upper side) and one just below (lower side) a carrier frequency, that result from modulation of a carrier wave. Bând, → band; kenâr "side," variant karân "edge, limit;" Mid.Pers. karân, karânak, kenâr "edge, limit, boundary;" Av. karana- "side, boundary, end." |
sidereal axtari (#) Fr.: sidéral Of, relating to, or determined by or from stars. From M.Fr. sidereal, from L. sidereus "starry, astral," from sidus (genitive sideris) "star, constellation." Axtari, pertaining to axtar "star," probably a variant of setâré→ star. |
sidereal day ruz-e axtari (#) Fr.: jour sidéral The period of → Earth's rotation around its axis, the mean value of which is about 23h 56m 04.092s (23.934 470 hours). In other words, the interval between two successive passages of a star across a given → meridian. The sidereal day is 3 minutes 56 seconds shorter than the → mean solar day. The reason is that Earth moves a little less than a degree around the Sun during the time it takes for one full axial rotation. So, for the Sun to appear on the same meridian in the sky again after one full axial rotation, the Earth has to rotate one extra degree to bring the Sun into the same apparent meridian in the sky. This is also why the stars rise and set about 4 min earlier each day. |
sidereal hour angle zâviye-ye sâ'ati-ye axtari (#) Fr.: angle horaire The angle on the celestial sphere measured westward from the hour circle of the vernal equinox to that of the celestial body. → sidereal; → hour angle. |
sidereal month mâh-e axtari (#) Fr.: mois sidéral The time taken by the Moon to complete one revolution around the Earth with respect to a fixed, background star. The average time is 27.321 661 days (27d 7h 43m 11.5s). |
sidereal period dowre-ye axtari (#) Fr.: période sidérale |
sidereal revolution period dowre-ye gardeš-e axtari (#) Fr.: période de révolution sidérale The time taken by a planet or satellite to complete one revolution about its primary with respect to stars. For Earth, same as → sidereal year. → sidereal; → revolution; → period. |
sidereal rotation period dowre-ye carxeš-e axtari Fr.: période de rotation sidérale The rotation period of a celestial body with respect to fixed stars. For Earth, same as → sidereal day. |
sidereal time zamân-e axtari (#) Fr.: temps sidéral The time based upon → Earth's rotation with respect to the stars, with the → sidereal day as the unit of measurement. At the moment when the → vernal equinox crosses the → meridian in → upper culmination, sidereal time is equal to zero hours for that observing position. The → hour angle of the vernal equinox is equal to sidereal time. |
sidereal year sâl-e axtari (#) Fr.: année sidérale The interval between two successive passages of the Sun, in its apparent → annual motion around the → celestial sphere, through a particular point relative to stars. It is equal to 365.256356 days for the J2000.0 epoch and is 20m 24.5s longer than the → tropical year. |
siderite siderit (#) Fr.: sidérite 1) A mineral composed of iron carbonate, FeCO_{3}, that is a valuable ore of
→ iron. From Gk. sider- variant of sidero- before a vowel, from sideros "iron" + -ite a suffix with several senses, specifically some minerals or chemical compounds. |
siderolite siderolit (#) Fr.: sidérolithe, sidérolite The category of → meteorites commonly referred to as → stony-irons. The three classes of siderolites are → lodranites, → mesosiderites, and → pallasites. From Gk. sidero-, from sideros "iron" + -lite a combining form used in the names of minerals. |
siderophile âhandust Fr.: sidérophile Any → chemical element that prefers to combine with → iron rather than some other element. From Gk. sidero-, from sideros "iron" + → -phile. |
siderostat axtardâštâr Fr.: sidérostat A mirror arrangement with clock drive that reflects light from a celestial body to a fixed position. → coelostat; → heliostat. From L. sidero-, from sidus (genitive sideris) "star, constellation" + -stat prefix denoting something that stabilizes, keeps, fixes, from -stata, from Gk. -states "one that causes to stand," or statos "standing," from *sta- "to stand." Axtardâštâr, from axtar, → star, + dâštâr "holder, maintainer," from dâštan "to hold, maintain; to have; to possess;" Mid.Pers. dâštan; O.Pers./Av. dar- "to hold, keep back, maintain, keep in mind;" cf. Skt. dhr-, dharma- "law;" Gk. thronos "elevated seat, throne;" L. firmus "firm, stable;" Lith. daryti "to make;" PIE base *dher- "to hold, support." |
siemens (S) siemens (#) Fr.: siemens The SI unit of electrical conductance, equal to the reciprocal of the ohm and replacing the equivalent MKS unit. Named for the German electrical engineer Werner von Siemens (1816-1892). |
sieve of Eratosthenes qarbâl-e Eratosthenes (#) Fr.: crible d'Eratosthène A classical method of finding all → prime numbers up to any given number n. The method consists of listing all positive integers from 2 up to the given number and then deleting some of them sequentially in steps. For example, if we wish to find the primes less than or equal to 50, we proceed as follows. All integers from 2 to 50 are first written. The integers that are divisible by 2, other than 2, are crossed out from the list. Since 3 is the first integer greater than 2 that is not removed, all the integers divisible by 3, other than 3, are crossed out. We do the same with 5 and then 7. Since all composite integers ≤ 50 are divisible by 2, 3, 5, or 7 (i.e. ≤ √50), all the remaining integers not deleted are prime numbers: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, and 47. M.E. sive, O.E. sife "sieve;" cf. M.Du. seve, Du. zeef, O.H.G. sib, Ger. Sieb, of unknown origin. Related to sift; → Eratosthenes experiment. Qarbâl (variants qarbil, qarbir, qelber, qalbur, gerbâl), probably related to the PIE base *krei- "to sieve, separate;" cf. Gk. krinein "to separate, decide, judge," krisis "decision;" L. cribrum "sieve" (Fr. crible), cernere "to sift, separate;" O.E. hriddel "sieve;" O.Ir. criathar; O.Welsh cruitr "sieve." Pers. qarbâl loaned in Ar. as gharbala "to sift," itself loaned in It. garbellare; M.Fr. garbeler "to sift;" E. garble "to sift impurities from." |
sievert (Sv) sievert (#) Fr.: sievert The SI unit for the dose equivalent of ionizing radiation. One sievert represents a dosage of 1 → joule per kg of tissue, absorbed from the ionizing radiation. The effect of radiation depends on its total amount of energy, the type of radiation, and the energy levels of particular particles. The dose equivalent in sieverts of radiation is the product of the absorbed dose in → gray (Gy)s and a dimensionless numeric factor, called the quality factor or relative biological effectiveness, dependent on the type of radiation. The sievert has replaced the → rem as the unit of dose equivalent. 1 rem = 10^{-2} Sv. The unit honors the Swedish physicist Rolf Sievert (1898-1966), who worked over many years to measure and standardize the radiation doses used in cancer treatment. |
sight did (#) Fr.: visée The act or fact of seeing; field of vision. → line of sight. M.E., from O.E. gesiht, gesihð "thing seen;" cf. Dan. sigte, Swed. sigt, M.Du. sicht, Du. zicht, O.H.G. siht, Ger. Sicht, Gesicht, related to → sign. Did "sight, vision," past stem of didan "to see" (Mid.Pers. ditan "to see, regard, catch sight of, contemplate, experience;" O.Pers. dī- "to see;" Av. dā(y)- "to see," didāti "sees;" cf. Skt. dhī- "to perceive, think, ponder; thought, reflection, meditation," dādhye; Gk. dedorka "have seen"). |
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