Modelling of magnetic effects in near-field optics

Green's dyadic technique represents a powerful tool for calculations in electrodynamics, especially in modelling optical properties of nanoscopic objects. The method does not only provide field distributions, but also maps of susceptibilities and densities of states. Whereas the formalism is well established for dielectrics and electric fields, I present here a straight forward extension to tensors of both electric and magnetic type as well as mixed ones and furthermore to the situation where objects with dielectric and magnetic permeabilities are present together. As examples, characteristic field patterns are compared for elementary dielectric and magnetic perturbations. Green's tensors calculated for a coral structure reveal that mixed susceptibilities can exhibit other symmetries than pure electric or magnetic ones. Maps of all tensor components can thus give essential clues to the interpretation of near-field images. Received 15 December 2002 Published online 20 June 2003 RID="a" ID="a"Files “maths.ps” and “tensors.ps” are only available in electronic form at http://www.edpsciences.org RID="b" ID="b"e-mail: Ursula.Schroeter@uni-konstanz.de     

Existence for nonoscillatory solutions of higher-order nonlinear neutral difference equations

In this paper, we consider the following forced higher-order nonlinear neutral difference equation

     

Existence and stability of bounded solutions for a system of parabolic equations

In this paper we study the existence and the stability of bounded solutions of the following non-linear system of parabolic equations with homogeneous Dirichlet boundary conditions:

     

Multiplicity of positive solutions to a p-Laplacian equation involving critical nonlinearity

In this paper we deal with multiplicity of positive solutions to the p-Laplacian equation of the type

     

Small Solutions of Quadratic Diophantine Equations

We consider quadratic diophantine equations of the shape for a polynomial Q(X₁, ..., X_s) Z[X₁, ..., X_s] of degree 2.Let H be an upper bound for the absolute values of the coefficientsof Q, and assume that the homogeneous quadratic part of Q isnon-singular. We prove, for all s 3, the existence of a polynomialbound _s(H) with the following property: if equation (1) hasa solution x Z^s at all, then it has one satisfying For s = 3 and s = 4 no polynomial bounds _s(H) were previouslyknown, and for s 5 we have been able to improve existing boundsquite significantly. 2000 Mathematics Subject Classification11D09, 11E20, 11H06, 11P55.     

The blow-up rates for systems of heat equations with nonlinear boundary conditions

This paper deals with the blow-up rate estimates of positive solutions for systems of heat equations with nonlinear boundary conditions. The upper and lower bounds of blow-up rate are obtained.     

Oscillation of Forced Nonlinear Neutral Delay Difference Equations of First Order

Necessary and sufficient conditions are obtained for every solution of

First-Order Necessary Conditions of Optimality for Strongly Monotone Nonlinear Control Problems

Necessary conditions for the optimality of a pair (y*, u*) with respect to the cost functional g(y) + h(u) subject to AyBu + f are given in terms of generalized gradients. Here, g is locally Lipschitz, h is convex, A is a maximal strongly monotone operator, and B is linear. Two examples of applications of our necessary conditions to nonlinear partial differential equations of elliptic type are presented.     

Monodromy Approach to the Scaling Limits in Isomonodromy Systems

The isomonodromy deformation method is applied to the scaling limits in the linear N×N matrix equations with rational coefficients to obtain the deformation equations for the algebraic curves that describe the local behavior of the reduced versions for the relevant isomonodromy deformation equations. The approach is illustrated by the study of the algebraic curve associated with the n-large asymptotics in the sequence of the biorthogonal polynomials with cubic potentials.     

General Solution for Hamiltonians with Extended Cubic and Quartic Potentials

In terms of hyperelliptic functions, we integrate a two-particle Hamiltonian with quartic potential and additional linear and nonpolynomial terms in the Liouville integrable cases 1:6:1 and 1:6:8.