7,881 research outputs found
Cuscuton kinks and branes
In this paper, we study a peculiar model for the scalar field. We add the
cuscuton term in a standard model and investigate how this inclusion modifies
the usual behavior of kinks. We find the first order equations and calculate
the energy density and the total energy of the system. Also, we investigate the
linear stability of the model, which is governed by a Sturm-Liouville
eigenvalue equation that can be transformed in an equation of the Shcr\"odinger
type. The model is also investigated in the braneworld scenario, where a first
order formalism is also obtained and the linear stability is investigated.Comment: 21 pages, 9 figures; content added; to appear in NP
Identification of fullerene-like CdSe nanoparticles from optical spectroscopy calculations
Semiconducting nanoparticles are the building blocks of optical nanodevices
as their electronic states, and therefore light absorption and emission, can be
controlled by modifying their size and shape. CdSe is perhaps the most studied
of these nanoparticles, due to the efficiency of its synthesis, the high
quality of the resulting samples, and the fact that the optical gap is in the
visible range. In this article, we study light absorption of CdSe
nanostructures with sizes up to 1.5 nm within density functional theory. We
study both bulk fragments with wurtzite symmetry and novel fullerene-like
core-cage structures. The comparison with recent experimental optical spectra
allows us to confirm the synthesis of these fullerene-like CdSe clusters
Heuristic Backtracking Algorithms for SAT
In recent years backtrack search SAT solvers have been the subject of dramatic improvements. These improvements allowed SAT solvers to successfully replace BDDs in many areas of formal verification, and also motivated the development of many new challenging problem instances, many of which too hard for the current generation of SAT solvers. As a result, further improvements to SAT technology are expected to have key consequences in formal verification. The objective of this paper is to propose heuristic approaches to the backtrack step of backtrack search SAT solvers, with the goal of increasing the ability of the SAT solver to search different parts of the search space. The proposed heuristics to the backtrack step are inspired by the heuristics proposed in recent years for the branching step of SAT solvers, namely VSIDS and some of its improvements. The preliminary experimental results are promising, and motivate the integration of heuristic backtracking in state-of-the-art SAT solvers. 1
P-248 Futility and utility of two-stage hepatectomy
Meeting abstract in the European-Society-for-Medical-Oncology (ESMO) 21st World Congress on Gastrointestinal Cancer.info:eu-repo/semantics/publishedVersio
A model for vortex formation in magnetic nanodots
We use Monte Carlo simulation to study the vortex nucleation on magnetic
nanodots at low temperature. In our simulations, we have considered a simple
microscopic two-dimensional anisotropic Heisenberg model with term to describe
the anisotropy due to the presence of the nanodot edge. We have considered the
thickness of the edge, which was not considered in previous works, introducing
a term that controls the energy associated to the edge. Our results clearly
show that the thickness of the edge has a considerable influence in the vortex
nucleation on magnetic nanodots. We have obtained the hysteresis curve for
several values of the surface anisotropy and skin depth parameter (). The
results are in excellent agreement with experimental data
Compact Vortices
We study a family of Maxwell-Higgs models, described by the inclusion of a
function of the scalar field that represent generalized magnetic permeability.
We search for vortex configurations which obey first-order differential
equations that solve the equations of motion. We first deal with the asymptotic
behavior of the field configurations, and then implement a numerical study of
the solutions, the energy density and the magnetic field. We work with the
generalized permeability having distinct profiles, giving rise to new models,
and we investigate how the vortices behave, compared with the solutions of the
corresponding standard models. In particular, we show how to build compact
vortices, that is, vortex solutions with the energy density and magnetic field
vanishing outside a compact region of the plane.Comment: 9 pages, 12 figures; v2, motivation and references adde
First Order Formalism for Generalized Vortices
This work develops a procedure to find classes of Lagrangian densities that
describe generalizations of the Abelian Maxwell-Higgs, the Chern-Simons-Higgs
and the Maxwell-Chern-Simons-Higgs models. The investigation focuses on the
construction of models that support vortices that obey the stressless condition
and lead to first order differential equations which are compatible with the
equations of motion. The results induce the appearance of constraints that
restrict the choice of the Lagrangian densities, but help us to introduce an
auxiliary function that allows to calculate the energy without knowing the
explicit form of the solutions.Comment: 36 pages, 10 figures; new version, to appear in NP
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