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991.
We determine in closed form the general static solution with cylindrical symmetry to the Brans-Dicke equations for an energy-momentum tensor corresponding to that of the straight U(1) global string outside the core radius assuming that the Higgs boson field takes its asymptotic value. 相似文献
992.
A. B. Drovosekov N. M. Kreines D. I. Kholin V. F. Meshcheryakov M. A. Milyaev L. N. Romashev V. V. Ustinov 《JETP Letters》1998,67(9):727-732
The excitation spectrum in an [Fe/Cr]n multilayer structure with non-collinear magnetic ordering was studied by the ferromagnetic resonance (FMR) method in the
frequency interval 9.5–37 GHz at room temperature. Besides an acoustic branch, several additional modes were observed under
parallel excitation of resonance. The FMR spectrum was calculated analytically in a biquadratic exchange model, neglecting
in-plane anisotropy, for an infinite number of layers in the structure and numerically for a finite number of layers contained
in real samples. It was shown that the observed modes correspond to excitation of standing spin waves with wave vectors perpendicular
to the film plane.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 9, 690–695 (10 May 1998) 相似文献
993.
994.
The thermodynamic and transport properties of normal disordered conductors are strongly influenced by the proximity of a superconductor.
A cooperation between mesoscopic coherence and Andreev scattering of particles from the superconductor generates new types
of interference phenomena. A field theoretic approach is introduced which is capable of exploring both the averaged properties
and mesoscopic fluctuations of superconductor/normal-metal systems. As an example the method is applied to the study of the
level statistics of a SNS junction.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 1, 21–26 (10 January 1998)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
995.
D. B. Saakian 《JETP Letters》1998,67(6):440-444
A layered random spin model, equivalent to the generalized random energy model (GREM), is introduced. In analogy with diluted
spin systems, a diluted GREM (DGREM) is constructed. It can be applied to calculate approximately the thermodynamic properties
of spin glass models in low dimensions. For the Edwards-Anderson model it gives the correct critical dimension and 5% accuracy
for the ground state energy in two dimensions.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 6, 415–419 (25 March 1998)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
996.
997.
Limit theorems for the number of records in a sequence of independent nonidentically distributed random variables are obtained.
A generalization of the so-called Fα-scheme is given. Bibliography: 4 titles.
Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 216, 1994, pp. 42–51.
Translated by A. Sudakov. 相似文献
998.
Bohm M. Torven S.B. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1992,20(5):525-536
Recent measurements of the response to an applied step voltage in collisionless plasmas have demonstrated the importance of the initial ion density distribution for the resulting time evolution and the formation of electric double layers. The dynamic response of a plasma diode to an applied step voltage is studied by particle-in-cell simulations and an analytical model. It is shown that an ion-density cavity (a local ion-density minimum with a width of many Debye lengths) can support large potential drops for several electron transit times. The potential drop extends over a distance related to the cavity width. When the applied potential drop exceeds a certain critical value, which depends on the cavity depth, the drop instead concentrates in a cathode sheath, which also is the response obtained for homogeneous initial plasma. The existence regions for the two different response in the appropriate parameter plane are found from the simulations and shown to agree with the regions predicted analytically. The analytical potential profiles agree with those simulated 相似文献
999.
1000.