Fr.: équation d'Arrhenius
An important relationship in physical chemistry that combines the concepts of → activation energy and the → Maxwell-Boltzmann distribution law. It is expressed by: k = Ae-Ea/(RT), where k is the chemical → reaction rate, Ea is the activation energy, R is the → gas constant, and T is → temperature.
Named for Svante Arrhenius (1859-1927), Swedish chemist and physicist who suggested the relationship in 1889.
Fr.: temps d'arrivée
The precise time at which the gamma burst photons hit a detector. Measuring the time difference between the arrival time of the photons at different telescopes separated by known distances permits to determine the burst direction.
Zamân, → time; raseš n. from rasidan "to arrive," Mid.Pers. rasitan, O.Pers./Av. rasa- present stem of ar- "to move, go or come toward," cf. Skt. ar-, rcchati.
A slender, straight, generally pointed missile or weapon made to be shot from a bow and equipped with feathers at the end of the shaft near the → nock, for controlling flight (Dictionary.com). → Sagitta.
M.E. arewe, arwe, O.E. earh, possibly borrowed from O.N. ör; ultimately from PIE *arku- "bow and/or arrow," → arc.
Peykân "arrow, javelin" (cognate with afkan-, afkandan "to throw, cast away," parâkan-, parâkandan "to scatter, to disperse"), ultimately from Proto-Iranian *paiti-kan- "to throw against," from *paiti- "against, opposite, back" (cf. Mod.Pers. pâd- "against, contrary to;" Mid.Pers. pât-; O.Pers. paity "against, back, opposite to, toward, face to face, in front of;" Av. paiti; Skt. práti "toward, against, again, back, in return, opposite;" Pali pati-; Gk. proti, pros "face to face with, toward, in addition to, near;" PIE *proti) + *kan- "to throw."
A silver-gray black metallic → chemical element which is very brittle; symbol As. → Atomic number 33; → atomic weight 74.9216; → boiling point 613.0 °C (sublimation); → valence -3, 0, +3, or +5. The uncombined element is not considered poisonous, but many of its compounds are extremely so, and are used in medicine and for destroying pests. Its longest-lived radioactive → isotope, 73As, has a → half-life of 80.3 days.
M.E. arsenik, from O.Fr. arsenic, from L. arsenicum, from Gk. arsenikon "arsenic," adapted from Syriac (al) zarniqa "arsenic," from Mid.Pers. zarnik "arsenic," literally "gold-colored," probably because of the lemon-yellow color of arsenic trisulphide (Mod.Pers. zarnix, zarni "arsenic"), from zarr, zar "gold" (+ -ik→ -ic); Av. zaranya-, zarənu- "gold;" O.Pers. daraniya- "gold;" cf. Skt. hiranya- "gold;" also Av. zaray-, zairi- "yellow, green;" Mod.Pers. zard "yellow;" Skt. hari- "yellow, green;" Gk. khloe literally "young green shoot;" L. helvus "yellowish, bay;" Rus. zeltyj "yellow;" P.Gmc. *gelwaz; Du. geel; Ger. gelb; E. yellow.
Ârsenik, loan from Fr., as above.
The process or product of human activity which is the expression of creativity and/or imagination that appeals to the senses or emotions.
From O.Fr. art, from L. artem, (nominative ars) "art, skill, craft;" from PIE base *ar- "to fit, join;" cf. Mod.Pers. arm "arm, from the elbow to the shoulder;" Av. arma-, arəmo- "arm;" Skt. irma- "arm;" Gk. arthron "a joint;" L. armus "shoulder."
Honar, from Mid.Pers. hunar "skill, ability, virtue, manliness;" O.Pers. hūnarā- "abilities, skills;" Av. hunara- "ability, skill"; cf. Skt. sūnára- "powerful, joyous, beautiful;" Proto-Iranian *Hnar- "to be able, strong."
A blood vessel that conveys blood from the heart to any part of the body (Dictionary.com).
M.E. arterie, O.Fr. artaire, from L. arteria, from Gk. arteria "windpipe," also "an artery," as distinct from a vein; related to aeirein "to raise."
1) A nonfictional prose composition usually forming an independent
part of a publication in a magazine.
Article, from O.Fr. article, from L. articulus, diminutive of artus "a joint".
Vetâr, from Kurd. witâr "article, speech," from witten "to speak, say," from wit-; cf. Pers. vât "letter, word," vâžé "word;" Av. vac- "to speak, say;" Proto-Iranian *uac- "to say, speak;" → letter.
Fr.: objet fabriqué, artefact
1) An object made by a human being, typically one of cultural or historical
Not occurring naturally; produced by man.
M.E., from O.Fr., from L. artificialis "belonging to art," from artificium "craftsmanship."
Sâxtegi "artificial," from sâxtan "to build, to make," → structure.
Fr.: horizon artificiel
Fr.: langue artificielle
An artificially created language system for international communication or for a specific intellectual or scientific purpose. Examples include Esperanto, computer programing languages, → symbolic logic, and → tensor analysis.
Fr.: lumière artificielle
Any light other than that which proceeds from the heavenly bodies.
Fr.: satellite artificiel
A man-made equipment that orbits around Earth or a solar system body.
Fr.: étoile artificielle
In → adaptive optics, a point source created on the sky by means of a laser beam in order to correct for the → atmospheric turbulence. A laser tuned to the wavelength of 589 nm will excite sodium atoms at an altitude of ~ 100 km in the Earth's atmosphere, producing an artificial "star."
panbe-ye kuhi (#), ~ nasuz (#)
A family of fibrous mineral silicates that are incombustible, resistant to chemicals, and do not conduct electricity. In the past asbestos has been widely used for a range of fireproof materials and in the building industry. Asbestos causes very serious health problems if the fibers are inhaled (bronchial cancer, laryngeal cancer, and mesothelioma).
M.E. albeston, abestus, from O.Fr. abeste, abestos, from L. asbestos "quicklime," from Gk. asbestos, literally "inextinguishable," from → a- "not" + sbestos, verbal adjective from sbennynai "to quench."
Panbe-ye kuhi, literally "mountain cotton," from panbé,
→ cotton, + kuhi "pertaining to mountains,"
from kuh, → mountain.
Fr.: monter, s'élever
1) To move, climb, or go upward; mount; rise.
Farâzidan, from farâz "above, over, aloft."
Fr.: nœud ascendant
The point in an orbit where the orbiting body crosses a reference plane, such as the ecliptic or the celestial equator, going from south to north. The celestial longitude of the ascending node is one of the elements of the orbit. → descending node.
Ascending, from ascend, from L. ascendere "to climb up," from ad- "to" + scandere "to climb." Node, from L. nodus "knot".
Gereh "knot," from Mid.Pers. grih "knot." Farâzeši, relating to farâzeš "ascension," from farâzidan "to ascend," from farâz "up, upon, upward, aloft."
The act of ascending; ascent.
A standard code or protocol for displaying → characters as numbers. Each alphabetic, numeric, or special character is represented with a 7-bit binary number (a string of seven 0s or 1s). 128 possible characters are defined. For example, the ASCII code for uppercase C is 67 and for lowercase c is 99. Most computers use ASCII codes to represent text, which makes it possible to transfer data from one computer to another.
Short for American Standard Code for Information Interchange.
The powdery residue that remains after something is burnt. → ashen light.
M.E. a(i)sshe; O.E. asce, æsce; cf. Frisian esk, Dutch asch, O.N., O.H.G. aska, Ger. Asche; akin to Gk. azein "to dry up, parch," L. arere "be dry," → arid, Skt. asa- "ashes," PIE root *as- "to burn, glow."