Time domain study of the Drude–Born–Fedorov model for a class of heterogeneous chiral materials

We deal with the well‐posedness of the transient Maxwell equations in a particular class of heterogeneous isotropic chiral material modeled by the Drude–Born–Fedorov constitutive relations with different boundary conditions. A new formulation of the underlying evolution problems allows us to establish existence and uniqueness results. The selfadjointness of the curl operator multiplied by a piecewise smooth function in an appropriated Hilbert space is also proved. Copyright © 2012 John Wiley & Sons, Ltd.     

Modulation of rectification and negative differential resistance in graphene nanoribbon by nitrogen doping

By applying the nonequilibrium Green?s function formalism combined with density functional theory, we have investigated the electronic transport properties of two nitrogen-doped armchair graphene nanoribbon-based junctions M1 and M2. In the left part of M1 and M2, nitrogen atoms are doped at two edges of the nanoribbon. In the right part, nitrogen atoms are doped at one edge and at the center for M1 and M2, respectively. Obvious rectifying and negative differential resistance behaviors are found, which are strongly dependent on the doping position. The maximum rectification and peak-to-valley ratios are up to the order of 10⁴ in M2.     

Fresnel coefficients for a layer of NIM

Reflection and transmission of traveling and evanescent waves by a layer of material with a negative index of refraction (NIM) is studied by means of the Fresnel coefficients. We derive their values in the “NIM limit”, and we show that this limit is consistent with the exact solution. It is also indicated that simply substituting the negative values of the relative permittivity and permeability of the NIM material into the exact solution leads to incorrect results for evanescent waves.     

靛蓝胭脂红-高碘酸钾-草酸钠催化光度法测定钢中微量钒

研究了在1 mol/L磷酸介质中，钒(V)对KIO4氧化靛蓝胭脂红褪色反应的催化作用及草酸钠的活化作用，建立了一种测定钒的方法。无草酸钠时该体系为准零级反应，表观活化能为76.7 kJ/mol，在22℃时钒量在0～5mg/L范围内与?A呈线性，检出限为0.1　mg/L。在草酸钠存在下则为准一级反应，表观活化能为60.1 kJ/mol，钒量在0～mg/L范围内与1g(A0/A)呈线性，检出限为0.02mg/L。提高介质酸度，可显著降低反应温度。在NaF及尿素存在下，大多数常见离子无干扰。本法简便快速，选择性和灵敏度较高，用于钢中微量钒的直接测定，结果满意。     

On finite unions of ideals and cosets

Abstract

Although it is well known that the growth of Thompson's group F is exponential, the exact growth function is still unknown. Elements of its submonoid of positive words can be described using a binary rooted tree, whose norm can be computed assigning weights to each caret. Combining this fact with a combinatorial argument, the growth function of the submonoid is computed and thus providing a first step in the computation of the growth function of the group, as well as a lower bound for the growth rate for the group.     

Bell’s Theorem,Many Worlds and Backwards-Time Physics: Not Just a Matter of Interpretation

The classic “Bell’s Theorem” of Clauser, Holt, Shimony and Horne tells us that we must give up at least one of: (1) objective reality (aka “hidden variables”); (2) locality; or (3) time-forwards macroscopic statistics (aka “causality”). The orthodox Copenhagen version of physics gives up the first. The many-worlds theory of Everett and Wheeler gives up the second. The backwards-time theory of physics (BTP) gives up the third. Contrary to conventional wisdom, empirical evidence strongly favors Everett-Wheeler over orthodox Copenhagen. BTP allows two major variations—a many-worlds version and a neoclassical version based on Partial Differential Equations (PDE), in the spirit of Einstein. Section 2 of this paper discusses the origins of quantum measurement according to BTP, focusing on the issue of how we represent condensed matter objects like polarizers in a model “Bell’s Theorem” experiment. The backwards time telegraph (BTT) is not ruled out in BTP, but is highly speculative for now, as will be discussed. The views herein are not anyone’s official views, but this does constitute work produced on government time.     

Explicit solutions of the one‐dimensional Vlasov–Poisson system with infinite mass

A collisionless plasma is modelled by the Vlasov–Poisson system in one dimension. A fixed background of positive charge, dependent only upon velocity, is assumed and the situation in which the mobile negative ions balance the positive charge as |x| → ∞ is considered. Thus, the total positive charge and the total negative charge are infinite. In this paper, the charge density of the system is shown to be compactly supported. More importantly, both the electric field and the number density are determined explicitly for large values of |x|. Copyright © 2007 John Wiley & Sons, Ltd.     

Quadrature methods for highly oscillatory linear and nonlinear systems of ordinary differential equations: part I

This work presents methods of efficient numerical approximation for linear and nonlinear systems of highly oscillatory ordinary differential equations. We show how an appropriate choice of quadrature rule improves the accuracy of approximation as the frequency of oscillation grows. We present asymptotic and Filon-type methods to solve highly oscillatory linear systems of ODEs, and WRF method, representing a special combination of Filon-type methods and waveform relaxation methods, for nonlinear systems. Numerical examples support this paper. Dedicated to the memory of Rudolf Khanamiryan. AMS subject classification (2000)  65L05, 34E05, 34C15     

Boundary layers for parabolic perturbations of quasi‐linear hyperbolic problems

In this paper, we study the asymptotic relation between the solutions to the one‐dimensional viscous conservation laws with the Dirichlet boundary condition and the associated inviscid solution. We assume that the viscosity matrix is positive definite, then we prove the existence and the stability of the weak boundary layers by discussing nonlinear well‐posedness of the inviscid flow with certain boundary conditions. Copyright © 2009 John Wiley & Sons, Ltd.