11,370 research outputs found
Maxwell's theory on a post-Riemannian spacetime and the equivalence principle
The form of Maxwell's theory is well known in the framework of general
relativity, a fact that is related to the applicability of the principle of
equivalence to electromagnetic phenomena. We pose the question whether this
form changes if torsion and/or nonmetricity fields are allowed for in
spacetime. Starting from the conservation laws of electric charge and magnetic
flux, we recognize that the Maxwell equations themselves remain the same, but
the constitutive law must depend on the metric and, additionally, may depend on
quantities related to torsion and/or nonmetricity. We illustrate our results by
putting an electric charge on top of a spherically symmetric exact solution of
the metric-affine gauge theory of gravity (comprising torsion and
nonmetricity). All this is compared to the recent results of Vandyck.Comment: 9 pages, REVTeX, no figures; minor changes, version to be published
in Class. Quantum Gra
Unit hydrograph characterization of flow regimes leading to a streamflow estimation in ungauged catchments (regionalization)
Imaging Pulsed Laser Deposition oxide growth by in-situ Atomic Force Microscopy
To visualize the topography of thin oxide films during growth, thereby
enabling to study its growth behavior quasi real-time, we have designed and
integrated an atomic force microscope (AFM) in a pulsed laser deposition (PLD)
vacuum setup. The AFM scanner and PLD target are integrated in a single support
frame, combined with a fast sample transfer method, such that in-situ
microscopy can be utilized after subsequent deposition pulses. The in-situ
microscope can be operated from room temperature (RT) up to 700C and at
(process) pressures ranging from the vacuum base pressure of 10 mbar up
to 1 mbar, typical PLD conditions for the growth of oxide films. The
performance of this instrument is demonstrated by resolving unit cell height
surface steps and surface topography under typical oxide PLD growth conditions.Comment: 8 pages, 8 figure
Clinical presentation, treatment and outcome in 31 dogs with presumed primary colorectal lymphoma (2001-2013)
Recruiting and Nurturing a Pipeline of Future Basic Course Directors
This essay responds to the Basic Course Forum question about best practices for recruiting to and/or from the basic course
Semirelativistic stability of N-boson systems bound by 1/r pair potentials
We analyze a system of self-gravitating identical bosons by means of a
semirelativistic Hamiltonian comprising the relativistic kinetic energies of
the involved particles and added (instantaneous) Newtonian gravitational pair
potentials. With the help of an improved lower bound to the bottom of the
spectrum of this Hamiltonian, we are able to enlarge the known region for
relativistic stability for such boson systems against gravitational collapse
and to sharpen the predictions for their maximum stable mass.Comment: 11 pages, considerably enlarged introduction and motivation,
remainder of the paper unchange
Corrections to Sirlin's Theorem in Chiral Perturbation Theory
We present the results of the first two-loop calculation of a form factor in
full Chiral Perturbation Theory. We choose a specific
linear combination of and form factors (the one
appearing in Sirlin's theorem) which does not get contributions from order
operators with unknown constants. For the charge radii, the correction to
the previous one-loop result turns out to be significant, but still there is no
agreement with the present data due to large experimental uncertainties in the
kaon charge radii.Comment: 6 pages, Latex, 2 LaTeX figure
The Constitutive Relations and the Magnetoelectric Effect for Moving Media
In this paper the constitutive relations for moving media with homogeneous
and isotropic electric and magnetic properties are presented as the connections
between the generalized magnetization-polarization bivector and
the electromagnetic field F. Using the decompositions of F and ,
it is shown how the polarization vector P(x) and the magnetization vector M(x)
depend on E, B and two different velocity vectors, u - the bulk velocity vector
of the medium, and v - the velocity vector of the observers who measure E and B
fields. These constitutive relations with four-dimensional geometric
quantities, which correctly transform under the Lorentz transformations (LT),
are compared with Minkowski's constitutive relations with the 3-vectors and
several essential differences are pointed out. They are caused by the fact
that, contrary to the general opinion, the usual transformations of the
3-vectors , , , , etc. are
not the LT. The physical explanation is presented for the existence of the
magnetoelectric effect in moving media that essentially differs from the
traditional one.Comment: 18 pages, In Ref. [10] here, which corresponds to Ref. [18] in the
published paper in IJMPB, Z. Oziewicz's published paper is added. arXiv admin
note: text overlap with arXiv:1101.329
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