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951.
952.
Keka Chakraborty S K Paranjpe V Siruguri O D Jayakumar S K Kulshreshtha 《Pramana》1997,48(6):1115-1122
Neutron diffraction and M?ssbauer measurements have been carried out on the cubic Laves phase intermetallic TbMnFe. The magnetic
moment on the transition metal atom is found to be low, 0.2μ
B, at room temperature. This moment is temperature independent down to 10 K. Magnetic moment on the rare earth atom varies
from 2.5μ
B at 296 K to 7.27μ
B at 10 K. M?ssbauer spectra recorded at 298 K and 78 K have magnetic character but there is a large distribution of hyperfine
field values. Both these features arise due to magnetic frustration created in the sample due to the competing ferro and antiferromagnetic
interactions between the transition metal atoms. 相似文献
953.
It is shown that a completely ionized, classical, Coulombian plasma, placed in an adiabatic enclosure, possesses a stationary state. At the same time, a plasma placed in a thermostat recombines through triple collisions, with a velocity satisfactorily accounted for by well-known theoretical results. The results obtained by numerical modeling have shown that, for a plasma placed in an adiabatic enclosure, the ergodic assumption is not valid. Various possible kinetic mechanisms, ensuring the existence of a stationary state of the adiabatically enclosed plasma, are considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 3–34, November, 1991. 相似文献
954.
S. N. Lakaev 《Theoretical and Mathematical Physics》1992,91(1):362-372
The existence of bound states and resonances of the Hamiltonian of a system ofN different quantum lattice particles with nonvanishingN-particle short-range interaction is proved. The dependence of the bound states and the resonances on the coupling constant and the quasimomentum is studied.Samarkand State University. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 91, No. 1, pp. 51–65, April, 1992. 相似文献
955.
Carmelo Nú¯nez 《Annali di Matematica Pura ed Applicata》1992,161(1):43-56
Summary Let K be a compact Hausdorff space and let E be a Banach space. We denote by C(K, E) the Banach space of all E-valued continuous functions defined on K, endowed with the supremum norm. We study in this paper Banach-Saks operators defined on C(K, E) spaces. We characterize these operators for a large class of compacts K (the scattered ones), or for a large class of Banach spaces E (the superreflexive ones). We also show by some examples that our theorems can not be extended directly.Partially supported by C.A.I.C.Y.T. grant 0338-84. The author wishes to thank Professor F.Bombal for his encouragement. 相似文献
956.
R. P. Spielmann Jin Zhen H. J. Triebel V. Nicolas M. Heller E. Bü cheler 《Magnetic resonance imaging》1992,10(6):893-901
To correlate the appearance of poststenotic jets on gradient echo images with features of localized Doppler spectra of the jets, we studied an in vitro model of steady flow-through stenoses of 86, 96, and 99% area reduction. As fluids, water and a 40% glycerol solution in water were used. MRI was performed with a 1.5 T whole body imager and gradient echo images were obtained in planes parallel to the direction of flow. Doppler spectra were acquired separately from the MR measurements at 1 cm intervals for a distance of 10 cm downstream from the stenosis. Poststenotic signal void was observed for water and for the 40% glycerol solution only if the mean velocity within the stenosis exceeded a limit of 50–60 cm/sec. On the MR images, the jets could be divided into two segments: A proximal jet segment of uniform width equal to the diameter of the stenosis, followed by a distal jet segment which was characterized by broadening and then dissipating signal void. Except for the 99% stenosis, a high signal intensity core was present within the proximal jet segment. In the proximal jet segment, the Doppler measurements showed a low temporal fluctuation of the maximal flow velocity and only little flow opposite to the main flow direction. In the distal jet segment, the velocity fluctuation and the intensity of reverse flow increased sharply. The high signal intensity core of the jet was associated with a poststenotic zone of constant maximal flow velocity. The results demonstrate a close relationship between characteristic features of poststenotic jets in MRI and pulsed Doppler sonography. 相似文献
957.
A. N. Kochubei 《Ukrainian Mathematical Journal》1992,44(7):836-840
A manifold M with semi-Riemannian almost product structure invariant relative to a transformation group G is considered. A connection with special G-invariance property is constructed in the corresponding bundle of frames.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 44, No. 7, pp. 926–931, July, 1992. 相似文献
958.
959.
Summary We discuss a null experiment to search for the fifth force at ranges around 10 km. It is proposed to use a three-axis gravity
gradiometer to measure the trace of the Earth gravity tensor from a freely falling elevator dropped by a balloon. The main
error sources are considered to some extent.
Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990. 相似文献
960.
I. I. Murav'ev E. V. Chernikova A. D. Shatova A. M. Yancharina 《Russian Physics Journal》1992,35(11):1008-1011
An experimental study has been made of the characteristics of radiation from a dispersing helium plasma. From measurements of the space-time dependence of the line intensities of the helium 23P — n3D series we obtained the distribution of the populations of the n3D levels for n=3–10. The study has shown that over a wide range of conditions the high-lying levels (n=5–10) are in equilibrium with electrons while a substantial deviation from equilibrium is observed for levels n=3, 4. From the energy distribution of the populations of the upper levels we determined the space-time dependence of the electron temperature, which reflects the process of effective electron cooling during dispersal of the plasma. The gas temperature was estimated from the populations of helium singlet and triplet levels with n=5. The time distribution of the electron density in the plasma was found from the Stark broadening of the spectral lines.Deceased.V. D. Kuznetsov Siberian Physicotechnical Institute, Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 15–19, November, 1992. 相似文献