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71.
Jean Gay Franois Fressin Jean-Pierre Rivet Yves Rabbia Christophe Buisset 《Comptes Rendus Physique》2005,6(10):1169-1175
We present a new type of stellar interfero-coronagraph, the ‘CIAXE’, which is a variant of the ‘AIC’, the Achromatic Interfero-Coronagraph. The CIAXE is characterized by a very simple, compact and fully coaxial optical combination. Indeed, contrarily to the classical AIC which has a Michelson interferometer structure, the CIAXE delivers its output beam on the same axis as the input beam. This will ease its insertion in the focal instrumentation of existing telescopes or next generation ones. Such a device could be a step forward in the field of instrumental search for exoplanets. To cite this article: J. Gay et al., C. R. Physique 6 (2005). 相似文献
72.
Carlos Gay Gary E. Thomas 《Journal of Quantitative Spectroscopy & Radiative Transfer》1981,25(4):351-380
We have developed a new approach toward solving problems of linear radiative relaxation of LTE temperature perturbations in a plane-parallel atmosphere of finite extent. We show that the mathematical problem is one of solving an integral eigenvalue equation, for which non-trivial solutions exist only for discrete values of the radiative relaxation time. The solutions for the spatial part of the perturbation constitute a complete and orthogonal set of basis functions, making it possible to solve more general problems of temperature relaxation. In applying this method to radiative relaxation in the middle atmosphere of earth, we show how the additional influences of photochemical coupling, advection by winds, and eddy diffusion by small-scale turbulence may be easily included using matrix perturbation techniques. We have solved the homogeneous integral equation for a wide variety of vertical thicknesses in an idealized homogeneous slab medium. Adopting a number of different analytic line profiles (rectangular, Doupler, Voigt, and Lorentz) we have obtained numerical solutions using an exponential-kernel method for solving the integral equation. The discrete eigenvalue “spectrum” is presented for vertical optical depths (0–103) at line-center, and is used in solving several initial-value problems for a decaying temperature perturbation. We find that the eigenvalue spectrum is bounded from above by the lowest-order eigenvalue, and bounded from below by the familiar transparent approximation. The dependence of the lowest even eigenvalue on optical depth and the relative separation of the higher eigenvalues are found to depend sensitively on the line profile. 相似文献
73.
C. Dionisi R. Armenteros J. Diaz Ph. Gavillet J.B. Gay A. Gurtu R.J. Hemingway M. Mazzucato P. Trepagnier R. Blokzijl G.G.G. Massaro B. Jongejans J. Engelen J.J. Timmermans R.T. Van De Walle B. Foster P.R. Lamb W.L. McDowell 《Physics letters. [Part B]》1978,78(1):154-157
Evidence is presented for an I = 1 enhancement observed in the reactions K?p→Λ(Σ)K01K±π? at inciden momentum. The mass and width of the proposed new Y1 are, respectively, (1553 ± 7) MeV) and (80 ± 30) MeV. A decay branching ratio is also obtained. 相似文献
74.
T Gay 《The Journal of the Acoustical Society of America》1978,63(1):223-230
The purpose of this experiment was to study the effects of changes in speaking rate on both the attainment of acoustic vowel targets and the relative time and speed of movements toward these presumed targets. Four speakers produced a number of different CVC and CVCVC utterances at slow and fast speaking rates. Spectrographic measurements showed that the midpoint format frequencies of the different vowels did not vary as a function of rate. However, for fast speech the onset frequencies of second formant transitions were closer to their target frequencies while CV transition rates remained essentially unchanged, indicating that movement toward the vowel simply began earlier for fast speech. Changes in both speaking rate and lexical stress had different effects. For stressed vowels, an increase in speaking rate was accompanied primarily by a decrease in duration. However, destressed vowels, even if they were of the same duration as quickly produced stressed vowels, were reduced in overall amplitude, fundamental frequency, and to some extent, vowel color. These results suggest that speaking rate and lexical stress are controlled by two different mechanisms. 相似文献
75.
76.
D. C. Dejongh S. C. Perricone M. L. Gay W. Korytnyk 《Journal of mass spectrometry : JMS》1968,1(1):151-166
The mass spectra of the different forms of vitamin B6, some metabolites and antimetabolites, and some analogs are reported. The free bases are suitable for study, but the 5-phosphates are not sufficiently volatile. The hydrochloride salts dissociate thermally in the inlet system into the free base and HCl and give the spectrum of the free base with the spectrum of HCL superimposed on it. The compounds studied are: pyridoxol, pyridoxamine and pyridoxal, which are different forms of vitamin B6; 4-pyridoxic acid and its lactone, 5-pyridoxic acid lactone, isopyridoxal, 5-formyl-3-hydroxy-2-methylpyridine-4-carboxylic acid, and 3-hydroxy-2-methylpyridine-4,5-dicarboxylic acid, which are vitamin B6 metabolites; α4-and α5-deoxypyridoxol, 3-deoxypyridoxol, and 4- and 5- norpyridoxol, which are antimetabolites and analogs of vitamin B6. 相似文献
77.
The synthesis and mesomorphic properties of a new type of ferroelectric liquid crystals and dopants (for induced ferroelectric phases) containing cis or trans disub-stituted thiiranes as the chiral unit are described. A comparison of the thiiranes with the corresponding oxiranes is given. In the thiirane series the tendency to exhibit mesophases is less pronounced. S*C phases occur for three aromatic cores in the mesogenic part of the molecule. The temperature ranges of the liquid crystal phases are broader and the transition temperatures are higher in the trans compared with cis configured thiiranes and oxiranes. Cis configured thiiranes exhibit a higher spontaneous polarization than the corresponding trans compounds. 相似文献
78.
79.
Carlos Gay 《Journal of Quantitative Spectroscopy & Radiative Transfer》1984,31(5):423-438
The problem of the dissipation of temperature perturbations in a finite homogeneous atmosphere is solved for the situation in which the temperature at one boundary is maintained constant (that is, the temperature perturbation is zero for all times) while energy can be freely radiated to space through the other boundary. Exact solutions are shown for the exponential-sum fit to the kernel of the basic integral equation. These solutions constitute the set of radiative eigenfunctions. Also, approximate solutions in terms of the radiative eigenfunctions in the diffusion approximation (one exponential term in the expansion of the kernel) are obtained. These, in turn, are used in the solution of an initial value problem. The constant temperature boundary condition simulates the interface between two regions in one of which the relaxation processes are much more rapid than the purely radiative relaxation of the other. 相似文献
80.
C. Brenner Mariotto M.B. Gay Ducati G. Ingelman 《The European Physical Journal C - Particles and Fields》2002,23(3):527-538
Both hard and soft QCD dynamics are important in charmonium production, as presented here through a next-to-leading order
QCD matrix element calculation combined with the color evaporation model. The observed and distributions of in hadroproduction at fixed target and collider energies are reproduced. Quite similar results can also be obtained in a more phenomenologically useful Monte Carlo
event generator where the perturbative production of pairs is instead obtained through leading order matrix elements and the parton shower approximation of the higher order processes.
The soft dynamics may alternatively be described by the soft color interaction model, originally introduced in connection
with rapidity gaps. We also discuss the relative rates of different charmonium states and introduce an improved model for
mapping the continuous mass spectrum on the physical charmonium resonances
Received: 29 November 2001 / Published online: 1 March 2002 相似文献