373 research outputs found
Electromagnetic shape resonances of a dielectric sphere and radiation of portable telephones
The frequency band used by cellular telephones includes the eigenfrequencies
of a dielectric sphere with physical characteristics close to those of a human
head. Proceeding from the spatial features of the natural modes of such a
sphere we propose an independent and clear evident accuracy test for the
complicated numerical calculations which are conducted when estimating the
potential hazard due to the use of cellular telephones, in particular, for the
check of a proper handling of the electromagnetic shape resonances of a human
head.Comment: 10 pages, 1 figure with 2 eps file
Neutrino mass spectrum from gravitational waves generated by double neutrino spin-flip in supernovae
The supernova (SN) neutronization phase produces mainly electron ()
neutrinos, the oscillations of which must take place within a few
mean-free-paths of their resonance surface located nearby their neutrinosphere.
The state-of-the-art on the SN dynamics suggests that a significant part of
these can convert into right-handed neutrinos in virtue of the
interaction of the electrons and the protons flowing with the SN outgoing
plasma, whenever the Dirac neutrino magnetic moment be of strength , with being the Bohr magneton. In the
supernova envelope, part of these neutrinos can flip back to the left-handed
flavors due to the interaction of the neutrino magnetic moment with the
magnetic field in the SN expanding plasma (Kuznetsov & Mikheev 2007; Kuznetsov,
Mikheev & Okrugin 2008), a region where the field strength is currently
accepted to be ~G. This type of oscillations were
shown to generate powerful gravitational wave (GW) bursts (Mosquera Cuesta
2000, Mosquera Cuesta 2002, Mosquera Cuesta & Fiuza 2004, Loveridge 2004). If
such double spin-flip mechanism does run into action inside the SN core, then
the release of both the oscillation-produced s, s and the GW
pulse generated by the coherent spin-flips provides a unique emission
offset for measuring the
travel time to Earth. As massive s get noticeably delayed on its
journey to Earth with respect to the Einstein GW they generated during the
reconversion transient, then the accurate measurement of this time-of-flight
delay by SNEWS + LIGO, VIRGO, BBO, DECIGO, etc., might readily assess the
absolute mass spectrum.Comment: 14 pages, 2 figures, ApJ aastex.cls style. In press by The
Astrophysical Journa
Neutrino Oscillations Induced by Gravitational Recoil Effects
Quantum gravitational fluctuations of the space-time background, described by
virtual D branes, may induce neutrino oscillations if a tiny violation of the
Lorentz invariance (or a violation of the equivalence principle) is imposed. In
this framework, the oscillation length of massless neutrinos turns out to be
proportional to M/E^2, where E is the neutrino energy and M is the mass scale
characterizing the topological fluctuations in the vacuum. Such a functional
dependence on the energy is the same obtained in the framework of loop quantum
gravity.Comment: 5 pages, LaTex fil
Noninvasive electrocardiographic imaging of dynamic atrioventricular delay programming in a patient with left bundle branch block
Introduction
The response to cardiac resynchronization therapy (CRT) is determined by various factors, including left ventricular (LV) lead location, atrioventricular (AV) delay, and inter-/intraventricular delays. Advances in quadripolar lead technology and device algorithms have improved patient response, yet selection of optimal settings remains challenging. Studies have shown acute improvement in electrical synchrony with manual AV optimization by fusion optimized intervals1,2; automated device algorithms, for example AdaptivCRT (Medtronic, Minneapolis, MN),3 SmartDelay (Boston Scientific, Marlborough, MA),4 and SyncAVTM (Abbott, Sylmar, CA)5; and pacing from multiple LV lead electrodes with MultiPoint Pacing (MPP).6,7 The aim of this clinical case report was to evaluate the acute benefits of SyncAV Plus in the new-generation, Bluetooth-enabled GallantTM CRT device (Abbott, Sylmar, CA). SyncAV Plus continually programs the paced AV delay shorter than the intrinsic PR interval by a programmable offset (% of PR duration) to synchronize intrinsic and ventricular paced activation wavefronts. Twelve-lead electrocardiogram (ECG) and noninvasive electrocardiographic imaging (ECGi) epicardial mapping analyses were performed to characterize the impact of SyncAV Plus on electrical synchrony during a range of CRT programming strategies, including biventricular (BiV) pacing, MPP, LV-only pacing, and LV-only pacing with MPP
On the influence of the magnetic field of the GSI experimental storage ring on the time-modulation of the EC-decay rates of the H-like mother ions
We investigate the influence of the magnetic field of the
Experimental storage ring (ESR) at GSI on the periodic time-dependence of the
orbital K-shell electron capture decay ) rates of the H--like heavy ions.
We approximate the magnetic field of the ESR by a uniform magnetic field.
Unlike the assertion by Lambiase et al., arXiv: 0811.2302 [nucl-th], we show
that a motion of the H-like heavy ion in a uniform magnetic field cannot be the
origin of the periodic time-dependence of the EC-decay rates of the H-like
heavy ions.Comment: 3 pages, 1 figur
Spin Flavor Conversion of Neutrinos in Loop Quantum Gravity
Loop quantum gravity theory incorporates a new scale length which
induces a Lorentz invariance breakdown. This scale can be either an universal
constant or can be fixed by the momentum of particles ().
Effects of the scale parameter and helicity terms occurring in the
dispersion relation of fermions are reviewed in the framework of spin-flip
conversion of neutrino flavors.Comment: 7 pages, no figur
Effects of CPT and Lorentz Invariance Violation on Pulsar Kicks
The breakdown of Lorentz's and CPT invariance, as described by the Extension
of the Standard Model, gives rise to a modification of the dispersion relation
of particles. Consequences of such a modification are reviewed in the framework
of pulsar kicks induced by neutrino oscillations (active-sterile conversion). A
peculiar feature of the modified energy-momentum relations is the occurrence of
terms of the form \delta {\bbox \Pi}\cdot {\bf {\hat p}}, where \delta
{\bbox \Pi} accounts for the difference of spatial components of flavor
depending coefficients which lead to the departure of the Lorentz symmetry, and
, being the neutrino momentum. Owing to the
relative orientation of with respect to \delta {\bbox \Pi}, the
{\it coupling} \delta {\bbox \Pi}\cdot {\bf {\hat p}} may induce the
mechanism to generate the observed pulsar velocities. Topics related to the
velocity distribution of pulsars are also discussed.Comment: 10 pages, 1 figur
Radiation in Lorentz violating electrodynamics
Synchrotron radiation is analyzed in the classical effective Lorentz
invariance violating model of Myers-Pospelov. Within the full far-field
approximation we compute the electric and magnetic fields, the angular
distribution of the power spectrum and the total emitted power in the m-th
harmonic, as well as the polarization. We find the appearance of rather
unexpected and large amplifying factors, which go together with the otherwise
negligible naive expansion parameter. This opens up the possibility of further
exploring Lorentz invariance violations by synchrotron radiation measurements
in astrophysical sources where these amplifying factors are important.Comment: Presented at the Second Mexican Meeting on Theoretical and
Experimental Physics, El Colegio Nacional, Mexico City, 6-10 September 200
Spin-gravity coupling and gravity-induced quantum phases
External gravitational fields induce phase factors in the wave functions of
particles. The phases are exact to first order in the background gravitational
field, are manifestly covariant and gauge invariant and provide a useful tool
for the study of spin-gravity coupling and of the optics of particles in
gravitational or inertial fields. We discuss the role that spin-gravity
coupling plays in particular problems.Comment: 18 pages, 1 figur
Quantum physics in inertial and gravitational fields
Covariant generalizations of well-known wave equations predict the existence
of inertial-gravitational effects for a variety of quantum systems that range
from Bose-Einstein condensates to particles in accelerators. Additional effects
arise in models that incorporate Born reciprocity principle and the notion of a
maximal acceleration. Some specific examples are discussed in detail.Comment: 25 pages,1 figure,to appear in "Relativity in Rotating Frame
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