1,002 research outputs found
The Devon Island Expedition 1960-64
The establishment of the Arctic Institute's Devon Island Base Station and the progress of the research program in 1960 and 1961 were reported in brief summaries and preliminary field reports in Arctic 13:270-71 and 14:252-65, and a review of the research from September 1961 to September 1962 appeared in Arctic 15:317-320. Preliminary field reports for that period are presented here. ..
Two Mathematically Equivalent Versions of Maxwell's Equations
This paper is a review of the canonical proper-time approach to relativistic
mechanics and classical electrodynamics. The purpose is to provide a physically
complete classical background for a new approach to relativistic quantum
theory. Here, we first show that there are two versions of Maxwell's equations.
The new version fixes the clock of the field source for all inertial observers.
However now, the (natural definition of the effective) speed of light is no
longer an invariant for all observers, but depends on the motion of the source.
This approach allows us to account for radiation reaction without the
Lorentz-Dirac equation, self-energy (divergence), advanced potentials or any
assumptions about the structure of the source. The theory provides a new
invariance group which, in general, is a nonlinear and nonlocal representation
of the Lorentz group. This approach also provides a natural (and unique)
definition of simultaneity for all observers. The corresponding particle theory
is independent of particle number, noninvariant under time reversal (arrow of
time), compatible with quantum mechanics and has a corresponding positive
definite canonical Hamiltonian associated with the clock of the source.
We also provide a brief review of our work on the foundational aspects of the
corresponding relativistic quantum theory. Here, we show that the standard
square-root and the Dirac equations are actually two distinct
spin- particle equations.Comment: Appeared: Foundations of Physic
Study of Photoluminescence Behaviour of Porous Silicon Samples Prepared at 20 mA Current Density
The paper presents a study on a series of porous silicon films of various thicknesses, prepared at 20 mA current density using a photoluminescence fitting model to determine the average crystallite size of sphe-rical shaped interconnected silicon quantum dots. Discrepancy in photoluminescence behavior of the samples is well explained with this model.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3097
Isotopic Grand Unification with the Inclusion of Gravity (revised version)
We introduce a dual lifting of unified gauge theories, the first
characterized by the isotopies, which are axiom- preserving maps into broader
structures with positive-definite generalized units used for the representation
of matter under the isotopies of the Poincare' symmetry, and the second
characterized by the isodualities, which are anti-isomorphic maps with
negative-definite generalized units used for the representation of antimatter
under the isodualities of the Poincare' symmetry. We then submit, apparently
for the first time, a novel grand unification with the inclusion of gravity for
matter embedded in the generalized positive-definite units of unified gauge
theories while gravity for antimatter is embedded in the isodual isounit. We
then show that the proposed grand unification provides realistic possibilities
for a resolution of the axiomatic incompatibilities between gravitation and
electroweak interactions due to curvature, antimatter and the fundamental
space-time symmetries.Comment: 20 pages, Latex, revised in various details and with added reference
X-Ray Scattering Measurements of the Transient Structure of a Driven Charge-Density-Wave
We report time-resolved x-ray scattering measurements of the transient
structural response of the sliding {\bf Q} charge-density-wave (CDW) in
NbSe to a reversal of the driving electric field. The observed time scale
characterizing this response at 70K varies from 15 msec for driving
fields near threshold to 2 msec for fields well above threshold. The
position and time-dependent strain of the CDW is analyzed in terms of a
phenomenological equation of motion for the phase of the CDW order parameter.
The value of the damping constant, eV
seconds \AA, is in excellent agreement with the value
determined from transport measurements. As the driving field approaches
threshold from above, the line shape becomes bimodal, suggesting that the CDW
does not depin throughout the entire sample at one well-defined voltage.Comment: revtex 3.0, 7 figure
Electronic Conduction in Annealed Sulfur-Doped a-Si:H Films
In present work, the effect of annealing on dark and photo conductivity as well as the various causes of
conduction mechanics in S doped amorphous hydrogenated silicon films (a-Si:H) is discussed. The variation
of the dark conductivity as a function of temperature has been carried out on unannealed and annealed
(annealed at an optimized temperature of 300 °C) thin film samples and the activation energy of dark conductivity
of respective samples was also calculated at different temperatures. The Study concludes that at
high temperatures, an activated type mechanism is responsible for conduction in the a-Si:H films
Distinguishing sequences for partially specified FSMs
Distinguishing Sequences (DSs) are used inmany Finite State Machine (FSM) based test techniques. Although Partially Specified FSMs (PSFSMs) generalise FSMs, the computational complexity of constructing Adaptive and Preset DSs (ADSs/PDSs) for PSFSMs has not been addressed. This paper shows that it is possible to check the existence of an ADS in polynomial time but the corresponding problem for PDSs is PSPACE-complete. We also report on the results of experiments with benchmarks and over 8 * 106 PSFSMs. © 2014 Springer International Publishing
Electronic dynamic Hubbard model: exact diagonalization study
A model to describe electronic correlations in energy bands is considered.
The model is a generalization of the conventional Hubbard model that allows for
the fact that the wavefunction for two electrons occupying the same Wannier
orbital is different from the product of single electron wavefunctions. We
diagonalize the Hamiltonian exactly on a four-site cluster and study its
properties as function of band filling. The quasiparticle weight is found to
decrease and the quasiparticle effective mass to increase as the electronic
band filling increases, and spectral weight in one- and two-particle spectral
functions is transfered from low to high frequencies as the band filling
increases. Quasiparticles at the Fermi energy are found to be more 'dressed'
when the Fermi level is in the upper half of the band (hole carriers) than when
it is in the lower half of the band (electron carriers). The effective
interaction between carriers is found to be strongly dependent on band filling
becoming less repulsive as the band filling increases, and attractive near the
top of the band in certain parameter ranges. The effective interaction is most
attractive when the single hole carriers are most heavily dressed, and in the
parameter regime where the effective interaction is attractive, hole carriers
are found to 'undress', hence become more like electrons, when they pair. It is
proposed that these are generic properties of electronic energy bands in solids
that reflect a fundamental electron-hole asymmetry of condensed matter. The
relation of these results to the understanding of superconductivity in solids
is discussed.Comment: Small changes following referee's comment
Probabilistic Anonymity
The concept of anonymity comes into play in
a wide range of situations, varying from voting
and anonymous donations to postings on bulletin
boards and sending mails. A formal definition of
this concept has been given in literature in
terms of nondeterminism. In this paper, we
investigate a notion of anonymity based on
probability theory, and we we discuss the relation
with the nondeterministic one. We then formulate
this definition in terms of observables for
processes in the probabilistic -calculus, and
propose a method to verify automatically the
anonymity property. We illustrate the method by
using the example of the dining cryptographers
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