We consider the twistor descriptions of harmonic maps of the Riemann sphere into Kähler manifolds and Yang–Mills fields on four-dimensional Euclidean space. The motivation to study twistor interpretations of these objects comes from the harmonic spheres conjecture stating the existence of the bijective correspondence between based harmonic spheres in the loop space ΩG of a compact Lie group G a...

In [4], D. Osipov and A. Parshin developed an approach to harmonic analysis on higher dimensional local fields through categories of filtered vector spaces as in [3]. In the present paper we give a variant of this approach that behaves nicely for inductive arguments. We establish Pontryagin duality, the Fourier inversion formula, and a Plancherel formula for all dimensions. ∗This paper was writ...

Filtered-backprojection formulae for the tomographic reconstruction of three-dimensional, divergenceless vector fields from their line integrals (Doppler transforms) are obtained, for both the cases of longitudinal and transverse measurement. The longitudinal formula is numerically simulated, and shown to be robust in the presence of noise. If, in the longitudinal case, there are non-zero norma...

In time-harmonic acoustic fields, energy streamlines are defined as the integral curves of the power-flux density vector, averaged over a period. They provide a tool to visualize the details of propagation of energy. After reviewing the role of energy streamlines in the linear sampling method for acoustic inverse scattering, this work formulates a physical interpretation of the same qualitative...

We study de Wit-Hoppe-Nicolai supermembrane with emphasis on the winding in M-direction. We propose a SUSY algebra of the supermembrane in the Lorentz invariant form. We analyze the BPS conditions and argue that the area preserving diffeomorphism constraints associated with the harmonic vector fields play an essential role. We derive the first order partial differential equation that describes ...

“Symplectic” schemes for stochastic Hamiltonian dynamical systems are formulated through “composition methods or operator splitting methods ” proposed by Misawa 2001 . In the proposed methods, a symplectic map, which is given by the solution of a stochastic Hamiltonian system, is approximated by composition of the stochastic flows derived from simpler Hamiltonian vector fields. The global error...

The problem of determining a current density confined to a volume from measurements of the magnetic and electric fields it produces exterior to that volume is known to have nonunique solutions. Despite the nonuniqueness of the inversion we show that one may nevertheless uniquely determine certain moments of the vector spherical harmonic expansion of the current. It is demonstrated that the dete...

The Einstein-Maxwell equations in D-dimensions admitting (D−3) commuting Killing vector fields have been investigated. The existence of the electric, magnetic and twist potentials have been proved. The system is formulated as the harmonic map coupled to gravity on three-dimensional base space generalizing the Ernst system in the four-dimensional stationary Einstein-Maxwell theory. Some classes ...

Besides using standard radial basis functions, there are a few good reasons to look for kernels with special properties. This survey will provide several examples, starting from an introduction into kernel construction techniques. After providing the “missing” Wendland functions, we focus on kernels based on series expansions. These have some very interesting special cases, namely polynomial an...

We report a comprehensive numerical study of a type of quasi-phase-matched Cherenkov third harmonic generation in a nonlinear waveguide, and this Cherenkov third harmonic generation consists of a guided-to-guided second harmonic generation cascaded with a guided-to-radiated sum-frequency generation. Following the coupled-mode theory, the temperature-detuning characteristics of third harmonic (T...