8,410 research outputs found
Self-Interacting Electromagnetic Fields and a Classical Discussion on the Stability of the Electric Charge
The present work proposes a discussion on the self-energy of charged
particles in the framework of nonlinear electrodynamics. We seek magnet- ically
stable solutions generated by purely electric charges whose electric and
magnetic fields are computed as solutions to the Born-Infeld equa- tions. The
approach yields rich internal structures that can be described in terms of the
physical fields with explicit analytic solutions. This suggests that the
anomalous field probably originates from a magnetic excitation in the vacuum
due to the presence of the very intense electric field. In addition, the
magnetic contribution has been found to exert a negative pressure on the
charge. This, in turn, balances the electric repulsion, in such a way that the
self-interaction of the field appears as a simple and natural classical
mechanism that is able to account for the stability of the electron charge.Comment: 8 pages, 1 figur
Taxonomic results of the Bryotrop expedition to Zaire and Rwanda : 26., a new checklist of the mosses of Central Africa
Central Africa was one of the first regions in the tropics, if not the first, for which a checklist of mosses was compiled. In 1940, Demaret published the "Prodrome des Bryophytes du Congo Belge et du Ruanda-Urundi", followed by a supplement in 1946. In the 50 years since that time, numerous new contributions to the bryophyte flora of Central Africa have been made. Demaret added seven more publications on Zaire (formerly Belgian Congo). Potier de la Varde studied the bryophyte collections made during the surveys of the flora of the Central African volcanoes by Hedberg
Thermodynamics of black holes in -dimensional Einstein-Born-Infeld dilaton gravity
We construct a new class of -dimensional black hole
solutions in Einstein-Born-Infeld-dilaton gravity with Liouville-type potential
for the dilaton field and investigate their properties. These solutions are
neither asymptotically flat nor (anti)-de Sitter. We find that these solutions
can represent black holes, with inner and outer event horizons, an extreme
black hole or a naked singularity provided the parameters of the solutions are
chosen suitably. We compute the thermodynamic quantities of the black hole
solutions and find that these quantities satisfy the first law of
thermodynamics. We also perform stability analysis and investigate the effect
of dilaton on the stability of the solutions.Comment: 18 pages, 15 figure
Vertical cavity surface emitting laser action of an all monolithic ZnO-based microcavity
We report on room temperature laser action of an all monolithic ZnO-based
vertical cavity surface emitting laser (VCSEL) under optical pumping. The VCSEL
structure consists of a 2{\lambda} microcavity containing 8
ZnO/Zn(0.92)Mg(0.08)O quantum wells embedded in epitaxially grown
Zn(0.92)Mg(0.08)O/Zn(0.65)Mg(0.35)O distributed Bragg reflectors (DBRs). As a
prerequisite, design and growth of high reflectivity DBRs based on ZnO and
(Zn,Mg)O for optical devices operating in the ultraviolet and blue-green
spectral range are discussed.Comment: Copyright (2011) American Institute of Physics. This article may be
downloaded for personal use only. Any other use requires prior permission of
the author and the American Institute of Physics. The following article
appeared in Appl. Phys. Lett. 98, 011101 (2011) and may be found at
http://apl.aip.org/resource/1/applab/v98/i1/p011101_s
Nonperturbative calculation of Born-Infeld effects on the Schroedinger spectrum of the hydrogen atom
We present the first nonperturbative numerical calculations of the
nonrelativistic hydrogen spectrum as predicted by first-quantized
electrodynamics with nonlinear Maxwell-Born-Infeld field equations. We also
show rigorous upper and lower bounds on the ground state.
When judged against empirical data our results significantly restrict the
range of viable values of the new electromagnetic constant which is introduced
by the Born-Infeld theory.
We assess Born's own proposal for the value of his constant.Comment: 4p., 2 figs, 1 table; submitted for publicatio
Singularity-Free Electrodynamics for Point Charges and Dipoles: Classical Model for Electron Self-Energy and Spin
It is shown how point charges and point dipoles with finite self-energies can
be accomodated into classical electrodynamics. The key idea is the introduction
of constitutive relations for the electromagnetic vacuum, which actually
mirrors the physical reality of vacuum polarization. Our results reduce to
conventional electrodynamics for scales large compared to the classical
electron radius cm. A classical simulation for a
structureless electron is proposed, with the appropriate values of mass, spin
and magnetic moment.Comment: 3 page
Spontaneous Generation of Photons in Transmission of Quantum Fields in PT Symmetric Optical Systems
We develop a rigorous mathematically consistent description of PT symmetric
optical systems by using second quantization. We demonstrate the possibility of
significant spontaneous generation of photons in PT symmetric systems. Further
we show the emergence of Hanbury-Brown Twiss (HBT) correlations in spontaneous
generation. We show that the spontaneous generation determines decisively the
nonclassical nature of fields in PT symmetric systems. Our work can be applied
to other systems like plasmonic structure where losses are compensated by gain
mechanisms.Comment: 4 pages, 5 figure
Ultrahigh reflection from a medium with ultraslow group velocity
We show that an incident wavepacket at the boundary to a medium with
extremely slow group velocity, experiences enhanced reflection and a
substantial spatial and temporal distortion of the transmitted wave packet. In
the limit of vanishing group velocity, light cannot be transferred into the
medium due to its perfect reflectivity.Comment: 3 pages, 3 figure
Dirac-Kronig-Penney model for strain-engineered graphene
Motivated by recent proposals on strain-engineering of graphene electronic
circuits we calculate conductivity, shot-noise and the density of states in
periodically deformed graphene. We provide the solution to the
Dirac-Kronig-Penney model, which describes the phase-coherent transport in
clean monolayer samples with an one-dimensional modulation of the strain and
the electrostatic potentials. We compare the exact results to a qualitative
band-structure analysis. We find that periodic strains induce large pseudo-gaps
and suppress charge transport in the direction of strain modulation. The
strain-induced minima in the gate-voltage dependence of the conductivity
characterize the quality of graphene superstructures. The effect is especially
strong if the variation of inter-atomic distance exceeds the value a^2/l, where
a is the lattice spacing of free graphene and l is the period of the
superlattice. A similar effect induced by a periodic electrostatic potential is
weakened due to Klein tunnelling.Comment: 11 pages, 8 figure
Generating Functional for Gauge Invariant Actions: Examples of Nonrelativistic Gauge Theories
We propose a generating functional for nonrelativistic gauge invariant
actions. In particular, we consider actions without the usual magnetic term.
Like in the Born-Infeld theory, there is an upper bound to the electric field
strength in these gauge theories.Comment: 14 pages, 2 figures; v2: misprints correcte
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