CONDUCTION ELECTRON IN THE ANISOTROPIC MEDIUM

1993 ◽  
Vol 07 (22) ◽  
pp. 3899-3905
Author(s):  
VLADIMIR L. SAFONOV

A new model for describing free electrons and holes in crystals in the long-wavelength approximation is proposed. The crystalline anisotropy in the framework of this model is introduced by means of corresponding space-time geometry. The generalized Dirac’s equation is constructed and non-relativistic Hamiltonian containing energy terms of the order of c–2 is calculated. It is shown that the spin magnetic components depend on corresponding effective cyclotron masses. Applicability of the results of the proposed model to different experiments is discussed. For the one-dimensional case, a hypothesis of para-Fermi statistics is suggested which may appear to explain one more mechanism of high-T c superconductivity.

2007 ◽  
Vol 16 (09) ◽  
pp. 1497-1517 ◽  
Author(s):  
CHRISTIAN CORDA

With an enlighting analysis, Baskaran and Grishchuk have recently shown the presence and importance of the so-called "magnetic" components of gravitational waves (GWs), which have to be taken into account in the context of the total response functions of interferometers for GWs propagating from arbitrary directions. In this paper, more detailed angular and frequency dependences of the response functions for the magnetic components are given in the approximation of wavelength much larger than the linear dimensions of the interferometer, with a specific application to the parameters of the LIGO and Virgo interferometers. The results of this paper agree with the work of Baskaran and Grishchuk, in which it has been shown that the identification of "electric" and "magnetic" contributions is unambiguous in the long-wavelength approximation. At the end of this paper, the angular and frequency dependences of the total response functions of the LIGO and Virgo interferometers are given. In the high-frequency regime, the division on "electric" and "magnetic" components becomes ambiguous, thus the full theory of gravitational waves has to be used. Our results are consistent with the ones of Baskaran and Grishchuk for this case.


2020 ◽  
Vol 75 (8) ◽  
pp. 727-738 ◽  
Author(s):  
Ramzy M. Abumandour ◽  
Islam M. Eldesoky ◽  
Mohamed H. Kamel ◽  
Mohamed M. Ahmed ◽  
Sara I. Abdelsalam

AbstractIn the article, the effects of the thermal viscosity and magnetohydrodynamic on the peristalsis of nanofluid are analyzed. The dominant neutralization is deduced through long wavelength approximation. The analytical solution of velocity and temperature is extracted by using steady perturbation. The pressure gradient and friction forces are obtained. Numerical results are calculated and contrasted with the debated theoretical results. These results are calculated for various values of Hartmann number, variable viscosity parameter and amplitude ratio. It is observed that the pressure gradient is reduced with an increase in the thermal viscosity parameter and that the Hartmann number enhances the pressure difference.


2016 ◽  
Vol 83 (5) ◽  
Author(s):  
Alan J. Levy ◽  
Xinyu Zhang

Tensile stability of healthy medial arterial tissue and its constituents, subject to initial geometrical and/or material imperfections, is investigated based on the long wavelength approximation. The study employs existing constitutive models for elastin, collagen, and vascular smooth muscle which comprise the medial layer of large elastic (conducting) arteries. A composite constitutive model is presented based on the concept of the musculoelastic fascicle (MEF) which is taken to be the essential building block of medial arterial tissue. Nonlinear equations governing axial stretch and areal stretch imperfection growth quantities are obtained and solved numerically. Exact, closed-form results are presented for both initial and terminal rates of imperfection growth with nominal load. The results reveal that geometrical imperfections, in the form of area nonuniformities, and material imperfections, in the form of constitutive parameter nonuniformities, either decrease or increase only slightly with increasing nominal load; a result which is to be expected for healthy tissue. By way of contrast, an examination of a simple model for elastin with a degrading stiffness gives rise to unbounded imperfection growth rates at finite values of nominal load. The latter result indicates how initial geometrical and material imperfections in diseased tissues might behave, a topic of future study by the authors.


1989 ◽  
Vol 04 (05) ◽  
pp. 1037-1053 ◽  
Author(s):  
KERSON HUANG

We give a critical review of the "triviality" of the λϕ4 theory, i.e., the vanishing of the renormalized self-coupling. Evidence from perturbation theory and Monte-Carlo simulations are cited. It is noted that (a) the theory is "trivial" but not entirely free, for there is spontaneous symmetry breaking; (b) perturbation theory is unreliable. Soluble examples with similar behavior are compared, in particular the Lee model and the 3D δ function potential. The latter case is especially important, for it shows that triviality is a symptom that the interaction is too singular, and suggests a cure. The import for the Higgs sector of the standard model is discussed. It is argued that, like the Fermi pseudopotential, the Higgs field is a long-wavelength approximation that should be used in lowest order perturbation theory only.


2003 ◽  
Vol 125 (2) ◽  
pp. 387-389 ◽  
Author(s):  
Jin Ho Song

A linear stability analysis is performed for a two-phase flow in a channel to demonstrate the feasibility of using momentum flux parameters to improve the one-dimensional two-fluid model. It is shown that the proposed model is stable within a practical range of pressure and void fraction for a bubbly and a slug flow.


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