82 research outputs found
Dirac-like Monopoles in Three Dimensions and Their Possible Influences on the Dynamics of Particles
Dirac-like monopoles are studied in three-dimensional Abelian Maxwell and
Maxwell-Chern-Simons models. Their scalar nature is highlighted and discussed
through a dimensional reduction of four-dimensional electrodynamics with
electric and magnetic sources. Some general properties and similarities of them
when are considered in Minkowski or Euclidian space are mentioned. However, by
virtue of the structure of the space-time in which they are considered a number
of differences among them take place. Furthermore, we pay attention to some
consequences of these objects when acting upon usual particles. Among other
subjects, special attention is given to the study of a Lorentz-violating
non-minimal coupling between neutral fermions and the field generated by a
monopole alone. In addition, an analogue of the Aharonov-Casher effect is
discussed in this framework.Comment: 20 pages. Latex format. No figures. Accepted for publication in Phys.
Rev.
Emission and absorption of photons and the black-body spectra in Lorentz-odd Electrodynamics
We study a number of issues related to the emission and absorption radiation
by non-relativistic electrons within the framework of a Lorentz-breaking
electrodynamics in (3+1) dimensions. Our main results concern how Planck-like
spectrum law is sensitive to terms that violate Lorentz symmetry. We have
realized that Planck law acquires extra terms proportional to the violating
parameters: for the CPT-odd model, the leading extra terms appear to be linear
or quadratic in these violating parameters according to the background vector
is parallel or perpendicular to the photon wave-vector. In the CPT-even case a
linear `correction' shows up. Among other possible ways to probe for these
violations, by means of the present results, we may quote the direct
observation of the extra contributions or an unbalancing in the mean occupation
number of photon modes in a given thermal bath.Comment: 11 pages, Late
Classical Solutions in a Lorentz-violating Maxwell-Chern-Simons Electrodynamics
We take as starting point the planar model arising from the dimensional
reduction of the Maxwell Electrodynamics with the (Lorentz-violating)
Carroll-Field-Jackiw term. We then write and study the extended Maxwell
equations and the corresponding wave equations for the potentials. The solution
to these equations show some interesting deviations from the usual MCS
Electrodynamics, with background-dependent correction terms. In the case of a
time-like background, the correction terms dominate over the MCS sector in the
region far from the origin, and establish the behaviour of a massless
Electrodynamics (in the electric sector). In the space-like case, the solutions
indicate the clear manifestation of spatial anisotropy, which is consistent
with the existence of a privileged direction is space.Comment: latex, 8 page
Geometrical pinning of magnetic vortices induced by a deficit angle on a surface: anisotropic spins on a conic space background
We study magnetic vortex-like excitations lying on a conic space background.
Two types of them are obtained. Their energies appear to be linearly dependent
on the conical aperture parameter, besides of being logarithmically divergent
with the sample size. In addition, we realize a geometrical-like pinning of the
vortex, say, it is energetically favorable for it to nucleate around the
conical apex. We also study the problem of two vortices on the cone and obtain
an interesting effect on such a geometry: excitations of the same charge, then
repealing each other, may nucleate around the apex for suitable cone apertures.
We also pay attention to the problem of the vortex pair and how its
dissociation temperature depends upon conical geometry.Comment: 13 pages, 06 figures, Latex. Version accepted for PHYSICS LETTERS
Scattering of charge carriers in graphene induced by topological defects
We study the scattering of graphene quasiparticles by topological defects,
represented by holes, pentagons and heptagons. For holes, we found that at low
concentration they give a negligible contribution to the resistivity. Whenever
pentagons or heptagons are introduced we realize that a fermionic current is
scattered by defects
Remarks on Dirac-like Monopole, Maxwell and Maxwell-Chern-Simons Electrodynamics in D=(2+1)
Classical Maxwell and Maxwell-Chern-Simons (MCS) Electrodynamics in (2+1)D
are studied in some details. General expressions for the potential and fields
are obtained for both models, and some particular cases are explicitly solved.
Conceptual and technical difficulties arise, however, for accelerated charges.
The propagation of electromagnetic signals is also studied and their
reverberation is worked out and discussed. Furthermore, we show that a
Dirac-like monopole yields a (static) tangential electric field. We also
discuss some classical and quantum consequences of the field created by such a
monopole when acting upon an usual electric charge. In particular, we show that
at large distances, the dynamics of one single charged particle under the
action of such a potential and a constant (external) magnetic field as well,
reduces to that of one central harmonic oscillator, presenting, however, an
interesting angular sector which admits energy-eigenvalues. Among other
peculiarities, both sectors, the radial and the angular one, present
non-vanishing energy-eigenvalues for their lowest level. Moreover, those
associated to the angle are shown to respond to discrete shifts of such a
variable. We also raise the question whether the formation of bound states is
possible in the system.Comment: 17 pages, 2 figures. To appear in Phys. Rev.
Four-dimensional anti-de Sitter black holes from a three-dimensional perspective: Full complexity
The dimensional reduction of black hole solutions in four-dimensional (4D)
general relativity is performed and new 3D black hole solutions are obtained.
Considering a 4D spacetime with one spacelike Killing vector, it is possible to
split the Einstein-Hilbert-Maxwell action with a cosmological term in terms of
3D quantities. Definitions of quasilocal mass and charges in 3D spacetimes are
reviewed. The analysis is then particularized to the toroidal charged rotating
anti-de Sitter black hole. The reinterpretation of the fields and charges in
terms of a three-dimensional point of view is given in each case, and the
causal structure analyzed.Comment: 26 pages, 1 figure, Uses revtex
Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.
BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362
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