11,694 research outputs found
Surface Waves and Forced Oscillations in QHE Planar Samples
Dispersion relations and polarizations for surface waves in infinite planar
samples in the QHE regime are explicitly determined in the small wavevector
limit in which the dielectric tensor can be considered as local. The wavelength
and frequency regions of applicability of the results extends to the infrared
region for typical experimental conditions. Then, standard samples with
millimetric sizes seem to be able to support such excitations. Forced
oscillations are also determined which should be generated in the 2DEG by
external electromagnetic sources. They show an almost frequency independent
wavevelength which decreases with the magnetic field. A qualitative model based
in these solutions is also presented to describe a recently found new class of
resonances appearing near the edge of a 2DEG in the QHE regime.Comment: latex file, 18 pages, 3 figures, spelling correcte
Coupled scalar fields Oscillons and Breathers in some Lorentz Violating Scenarios
In this work we discuss the impact of the breaking of the Lorentz symmetry on
the usual oscillons, the so-called flat-top oscillons, and the breathers. Our
analysis is performed by using a Lorentz violation scenario rigorously derived
in the literature. We show that the Lorentz violation is responsible for the
origin of a kind of deformation of the configuration, where the field
configuration becomes oscillatory in a localized region near its maximum value.
Furthermore, we show that the Lorentz breaking symmetry produces a displacement
of the oscillon along the spatial direction, the same feature is present in the
case of breathers. We also show that the effect of a Lorentz violation in the
flat-top oscillon solution is responsible by the shrinking of the flat-top.
Furthermore, we find analytically the outgoing radiation, this result indicates
that the amplitude of the outgoing radiation is controlled by the Lorentz
breaking parameter, in such away that this oscillon becomes more unstable than
its symmetric counterpart, however, it still has a long living nature
On the study of oscillons in scalar field theories: A new approach
In this work we study configurations in one-dimensional scalar field theory,
which are time-dependent, localized in space and extremely long-lived called
oscillons. It is investigated how the action of changing the minimum value of
the field configuration representing the oscillon affects its behavior. We find
that one of the consequences of this procedure, is the appearance of a pair of
oscillon-like structures presenting different amplitudes and frequencies of
oscillation. We also compare our analytical results to numerical ones, showing
excellent agreement
Case studies on the geological application of LANDSAT imagery in Brazil
The author has identified the following significant results. Sao Domingos Range, Pocos de Caldas, and Araguaia and Tocantins Rivers in Brazil were selected as test sites for LANDSAT imagery. The satellite images were analyzed using conventional photointerpretation techniques, and the results indicate the application of small scale image data in regional structural data analysis, geological mapping, and mineral exploration
MAMA: An Algebraic Map for the Secular Dynamics of Planetesimals in Tight Binary Systems
We present an algebraic map (MAMA) for the dynamical and collisional
evolution of a planetesimal swarm orbiting the main star of a tight binary
system (TBS). The orbital evolution of each planetesimal is dictated by the
secular perturbations of the secondary star and gas drag due to interactions
with a protoplanetary disk. The gas disk is assumed eccentric with a constant
precession rate. Gravitational interactions between the planetesimals are
ignored. All bodies are assumed coplanar. A comparison with full N-body
simulations shows that the map is of the order of 100 times faster, while
preserving all the main characteristics of the full system.
In a second part of the work, we apply MAMA to the \gamma-Cephei, searching
for friendly scenarios that may explain the formation of the giant planet
detected in this system. For low-mass protoplanetary disks, we find that a
low-eccentricity static disk aligned with the binary yields impact velocities
between planetesimals below the disruption threshold. All other scenarios
appear hostile to planetary formation
Information-Entropic Measure of Energy-Degenerate Kinks in Two-Field Models
We investigate the existence and properties of kink-like solitons in a class
of models with two interacting scalar fields. In particular, we focus on models
that display both double and single-kink solutions, treatable analytically
using the Bogomol'nyi--Prasad--Sommerfield bound (BPS). Such models are of
interest in applications that include Skyrmions and various
superstring-motivated theories. Exploring a region of parameter space where the
energy for very different spatially-bound configurations is degenerate, we show
that a newly-proposed momentum-space entropic measure called Configurational
Entropy (CE) can distinguish between such energy-degenerate spatial profiles.
This information-theoretic measure of spatial complexity provides a
complementary perspective to situations where strictly energy-based arguments
are inconclusive
The Resonance Overlap and Hill Stability Criteria Revisited
We review the orbital stability of the planar circular restricted three-body
problem, in the case of massless particles initially located between both
massive bodies. We present new estimates of the resonance overlap criterion and
the Hill stability limit, and compare their predictions with detailed dynamical
maps constructed with N-body simulations. We show that the boundary between
(Hill) stable and unstable orbits is not smooth but characterized by a rich
structure generated by the superposition of different mean-motion resonances
which does not allow for a simple global expression for stability.
We propose that, for a given perturbing mass and initial eccentricity
, there are actually two critical values of the semimajor axis. All values
are
unstable in the Hill sense. The first limit is given by the Hill-stability
criterion and is a function of the eccentricity. The second limit is virtually
insensitive to the initial eccentricity, and closely resembles a new resonance
overlap condition (for circular orbits) developed in terms of the intersection
between first and second-order mean-motion resonances.Comment: 33 pages, 14 figures, accepte
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