A performance criterion for an electronic detector, reciprocal of the corresponding → noise-equivalent power (D = 1/NEP).
A device whose main function is detection.
L.L. detector, from deteg(ere), → detect, + -tor suffix forming agent noun.
Âškârgar, from âškâr present-tense stem of âškâridan "to detect" + -gar a suffix of agent nouns, from kar-, 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").
An agent or factor that determines the nature of something or that fixes or
conditions an outcome.
From → determine + -ant suffix forming noun.
The act of deciding definitely and firmly; the result of such an act of decision.
Verbal noun of → determine.
1) General: To settle or decide by choice of alternatives or possibilities.
Âtarmidan, from âtarm + verb forming suffix -idan; âtarm from intensive prefix â- + tarm "limit, boundary," → term.
The belief that every event is necessitated by antecedent events and conditions together with the laws of nature. → deterministic physics.
Âtarmbâvari, from âtarm, → determine, + bâvari, noun of bâvar "beleif;" Mid.Pers. wâbar "beleif;" Proto-Iranian *uar- "to choose; to convince; to believe;" cf. Av. var- "to choose; to convince" varəna-, varana- "conviction, faith;" O.Pers. v(a)r- "to choose; to convince;" Skt. vr- "to choose," vara- "choosing."
Of, pertaining to, or dealing with → determinism.
From determinist + → -ic.
Fr.: physique déterministe
The classical representation of the laws of nature according to which a particular future state (B) will arise from a particular past one (A). In contrast to → quantum physics which deals with the probability for the transition from A to B.
Deterministic, adj. of determinism; → physics.
Fr.: théorie déterministe
A theory in which specification of the initial value of all relevant variables of the system is sufficient to calculate the past values and to predict the future values of such variables for any arbitrary time. Moreover, it is possible, for any arbitrary time, to assign a value to all the variables characterizing the system. In quantum mechanics, the time evolution of the → wave function, governed by the → Schrodinger equation, is deterministic. Quantum mechanics, however, is a non deterministic theory because of the probabilistic nature of the predictions for the values of the → observables of a quantum system.
Fr.: détoner, faire détoner, faire exploser
1) To set off a → detonation. 2) To explode or cause to explode.
From L. detonatus, p.p. of detonare "to thunder down, roar out," from → de- + tonare "to thunder," cf. Pers. tondar "thunder," Skt. stanáyati "thunders," tanyatá- "thundering," Gk. stonos "groan," stenein "to groan," Thôrr "the Old Norse god of thunder," P.Gmc. *thunraz (Du. donder, Ger. Donner "thunder," E. thunder, Fr. tonnerre), PIE base *(s)tene- "to resound, thunder."
Tarâkidan "to split, cleave; to make a noise in splitting," variants tarakidan, taraqidan, taraqqé "firecracker," from tarâk/tarak "split, cleft, crack; the noise of anything when splitting or cleaving," maybe related to Pers. dar-, daridan "to tear, cut," Av. dar- "to tear," dərəta- "cut," auua.dərənant- "shattering," Skt. dar- "to crack, split, break, burst," darati "he splits," cf. Gk. derma "skin," E. tear, Ger. zerren "to pull, to tear," zehren "to undermine, to wear out," PIE base *der- " to split, peel, flay."
Verbal noun of → detonate.
From L. deuter(ium), → deuterium, + -ate a suffix forming verbs from L. -atus (masc.), -ata (fem.), -atum (neut.).
Doteridan, infinitive from doteriom, → deuterium.
Past participle of → deuterate.
Fr.: espèce deutérée
Verbal noun of → deuterate.
The first heavy → isotope of
→ hydrogen (2H), the
→ nucleus of which consists of one
→ proton and one → neutron.
Like hydrogen, the deuterium atom has one
electron, and therefore has similar chemical properties to hydrogen, forming, e.g.,
→ heavy water (HDO). Deuterium is generated only during
→ Big Bang nucleosynthesis. It is destroyed in stars through the
reaction D + p → 3He + γ (→ deuterium burning).
As there is no net source of deuterium in stars, its abundance has decreased steadily since the
→ Big Bang, and any value measured today must be a lower limit
on the primordial value. However, → fractionation
processes lead to local → deuterium enhancements; see
→ deuterium abundance for more details. Theoretical models
of Big Bang nucleosynthesis predict D/H to be (2.61 ± 0.15) x 10-5
(Steigman et al. 2007, MNRAS 378, 576) and this is closely matched by measurements from
intergalactic Dα line absorption observations toward high-redshift quasars
that give 2.53±0.04 x 10-5 (Cooke et al. 2014, ApJ 781, 31).
From Gk. deutero-, combining form of deuterios "second" + -ium suffix occurring in scientific coinages on a Latin model. Coined in 1933 by U.S. chemist Harold C. Urey (1893-1981).
Fr.: abondance de deutérium
The number of → deuterium (D) atoms with respect to
→ hydrogen (H) in an astrophysical object.
Deuterium is a primordial product of → Big Bang nucleosynthesis.
According to theoretical models, the primordial D/H ratio is estimated to be
(2.61 ± 0.15) x 10-5 (Steigman et al. 2007, MNRAS 378, 576).
Nuclear reactions in stars convert D into
He tending to a lower D/H ratio in the → interstellar medium
over time (→ deuterium burning).
However, chemical and physical → fractionation
processes can produce local → enhancements in the D/H ratio.
For example, low-temperature ion-molecule reactions in
→ molecular cloud cores can enhance
the D/H ratio in icy grains by as much as two orders of magnitude
above that observed in the interstellar medium.
Fr.: combustion du deutérium
The fusion of a deuterium nucleus with a proton which produces the lightest isotope of helium: D + H → 3He + γ. Deuterium burning occurs in stellar cores at a temperature exceeding 106 K. The onset of deuterium burning marks the end of the → protostellar collapse. It is the only → nuclear reaction that occurs in → brown dwarfs. In normal stars, it is the second step in the → proton-proton chain which leads to the formation of 4He, allowing stars to arrive on the → main sequence.
Fr.: enrichissement de deutérium
The → enrichment of deuterium (D) with respect to
→ hydrogen (H) in
→ Solar System molecules
when compared with the D/H ratio in the
→ interstellar → solar nebula.
H-bearing molecules in → comets,
→ planets, and → chondrite
→ meteorites show a systematic D enrichment
relative to the → molecular hydrogen of the solar
nebula. Because there is no nuclear source for D in the Universe,
the observed → isotopic enrichment must have its
origin in chemical reactions having faster reaction rates for D than for H.
In the Solar nebula the → isotopic fractionation
of D between → water and H followed the reversible reaction:
deuterium enrichment factor
karvand-e pordâri-ye doteriom
Fr.: facteur d'enrichissement en deutérium