5,471 research outputs found
On the dynamic toroidal multipoles from localized electric current distributions
We analyze the dynamic toroidal multipoles and prove that they do not have an
independent physical meaning with respect to their interaction with
electromagnetic waves. We analytically show how the split into electric and
toroidal parts causes the appearance of non-radiative components in each of the
two parts. These non-radiative components, which cancel each other when both
parts are summed, preclude the separate determination of each part by means of
measurements of the radiation from the source or of its coupling to external
electromagnetic waves. In other words, there is no toroidal radiation or
independent toroidal electromagnetic coupling. The formal meaning of the
toroidal multipoles is clear in our derivations. They are the higher order
terms of an expansion of the multipolar coefficients of electric parity with
respect to the electromagnetic size of the source
Non-Kaehler Heterotic String Solutions with non-zero fluxes and non-constant dilaton
Conformally compact and complete smooth solutions to the Strominger system
with non vanishing flux, non-trivial instanton and non-constant dilaton using
the first Pontrjagin form of the (-)-connection} on 6-dimensional non-Kaehler
nilmanifold are presented. In the conformally compact case the dilaton is
determined by the real slices of the elliptic Weierstrass function. The dilaton
of non-compact complete solutions is given by the fundamental solution of the
Laplacian on .Comment: LaTeX 2e, 17 page
Exact dipolar moments of a localized electric current distribution
The multipolar decomposition of current distributions is used in many
branches of physics. Here, we obtain new exact expressions for the dipolar
moments of a localized electric current distribution. The typical integrals for
the dipole moments of electromagnetically small sources are recovered as the
lowest order terms of the new expressions in a series expansion with respect to
the size of the source. All the higher order terms can be easily obtained. We
also provide exact and approximated expressions for dipoles that radiate a
definite polarization handedness (helicity). Formally, the new exact
expressions are only marginally more complex than their lowest order
approximations
Avalanches, loading and finite size effects in 2D amorphous plasticity: results from a finite element model
Crystalline plasticity is strongly interlinked with dislocation mechanics and
nowadays is relatively well understood. Concepts and physical models of plastic
deformation in amorphous materials on the other hand - where the concept of
linear lattice defects is not applicable - still are lagging behind. We
introduce an eigenstrain-based finite element lattice model for simulations of
shear band formation and strain avalanches. Our model allows us to study the
influence of surfaces and finite size effects on the statistics of avalanches.
We find that even with relatively complex loading conditions and open boundary
conditions, critical exponents describing avalanche statistics are unchanged,
which validates the use of simpler scalar lattice-based models to study these
phenomena.Comment: Journal of Statistical Mechanics: Theory and Experiment, 2015, P0201
Exact dipolar moments of a localized electric current distribution
The multipolar decomposition of current distributions is used in many
branches of physics. Here, we obtain new exact expressions for the dipolar
moments of a localized electric current distribution. The typical integrals for
the dipole moments of electromagnetically small sources are recovered as the
lowest order terms of the new expressions in a series expansion with respect to
the size of the source. All the higher order terms can be easily obtained. We
also provide exact and approximated expressions for dipoles that radiate a
definite polarization handedness (helicity). Formally, the new exact
expressions are only marginally more complex than their lowest order
approximations
A Combined View of Sterile-Neutrino Constraints from CMB and Neutrino Oscillation Measurements
We perform a comparative analysis of constraints on sterile neutrinos from
the Planck experiment and from current and future neutrino oscillation
experiments (MINOS, IceCube, SBN). For the first time, we express the Planck
constraints on and from the Cosmic
Microwave Background in the parameter space used by oscillation experiments
using both mass-squared differences and mixing angles. In a model with a single
sterile neutrino species and using standard assumptions, we find that the
Planck data and the oscillation experiments measuring muon-neutrino
disappearance have similar sensitivity.Comment: 6 pages, 3 figures, Version accepted by Physics Letters B, minor
changes to text, results unchange
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