3,141 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
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
Vortices in Maxwell-Higgs models with a global factor
This paper deals with planar vortices in a generalized model that presents a
global factor which depends on the scalar field in the Nielsen-Olesen Lagrange
density. We show that the system supports a first order framework. Contrary to
what occurs with kinks in the line, planar vortices require the presence of
constraints that brings modifications into the first order equations. Novel
features are unveiled, such as finite energy configurations with infinite
energy density at the origin and the presence of parameters that modifies the
energy, keeping the solutions unchanged.Comment: 6 pages, 4 figure
Evolution of the fine-structure constant in the non-linear regime
We study the evolution of the fine-structure constant, , induced by
non-linear density perturbations in the context of the simplest class of
quintessence models with a non-minimal coupling to the electromagnetic field,
in which the two available free functions (potential and gauge kinetic
function) are Taylor-expanded up to linear order. We show that the results
obtained using the spherical infall model for an infinite wavelength
inhomogeneity are inconsistent with the results of a local linearized gravity
study and we argue in favour of the second approach. We also discuss recent
claims that the value of inside virialised regions could be
significantly different from the background one on the basis of these findings.Comment: 5 pages, 3 figure
Impacto da queimada e do pousio sobre a qualidade de um solo sob caatinga no semi-árido Nordestino.
Cardiopatias Congénitas Complexas: Influência do Diagnóstico Pré-Natal
INTRODUCTION:
Complex congenital heart disease is a group of severe conditions. Prenatal diagnosis has implications on morbidity and mortality for most severe conditions. The purpose of this work was to evaluate the influence of prenatal diagnosis and distance of residence and birth place to a reference center, on immediate morbidity and early mortality of complex congenital heart disease.
MATERIAL AND METHODS:
Retrospective study of complex congenital heart disease patients of our Hospital, born between 2007 and 2012.
RESULTS:
There were 126 patients born with complex congenital heart disease. In 95%, pregnancy was followed since the first trimester, with prenatal diagnosis in 42%. There was a statistically significant relation between birth place and prenatal diagnosis. Transposition of great arteries was the most frequent complex congenital heart disease (45.2%), followed by pulmonary atresia with ventricular septal defect (17.5%) and hypoplastic left ventricle (9.5%). Eighty-two patients (65.1%) had prostaglandin infusion and 38 (30.2%)were ventilated before an intervention. Surgery took place in the neonatal period in 73%. Actuarial survival rate at 30 days, 12 and 24 months was 85%, 80% and 75%, respectively. There was no statistically significant relation between prenatal diagnosis and mortality.
DISCUSSION:
Most patients with complex congenital heart disease did not have prenatal diagnosis. All cases with prenatal diagnosis were born in a tertiary center. Prenatal diagnosis did not influence significantly neonatal mortality, as already described in other studies with heterogeneous complex heart disease.
CONCLUSION:
prenatal diagnosis of complex congenital heart disease allowed an adequate referral. Most patients with complex congenital heart disease were not diagnosed prenatally. This data should be considered when planning prenatal diagnosis of congenital heart disease
- …