Global-String and Vortex Superfluids in a Supersymmetric Scenario

The main goal of this work is to investigate the possibility of finding the supersymmetric version of the U(1)-global string model which behaves as a vortex-superfluid. To describe the superfluid phase, we introduce a Lorentz-symmetry breaking background that, in an approach based on supersymmetry, leads to a discussion on the relation between the violation of Lorentz symmetry and explicit soft supersymmetry breakings. We also study the relation between the string configuration and the vortex-superfluid phase. In the framework we settle down in terms of superspace and superfields, we actually establish a duality between the vortex degrees of freedom and the component fields of the Kalb-Ramond superfield. We make also considerations about the fermionic excitations that may appear in connection with the vortex formation.Comment: 9 pages. This version presented the relation between Lorentz symmetry violation by the background and the appearance of terms that explicitly break SUS

Plane Gravitational Radiation from Neutrinos Source with Kalb-Ramond Coupling

In this work, we propose a model based on a non-minimal coupling of neutrinos to a Kalb-Ramond field. The latter is taken as a possible source for gravitational radiation. As an immediate illustration of this system, we have studied the case where gravitational (plane) wave solutions behave as damped harmonic oscillators.Comment: Presented at 7th Alexander Friedmann International Seminar on Gravitation and Cosmology, Joao Pessoa, Brazil, 29-05 Jul 200

Dilatonic, Current-Carrying Cosmic String

We study the implications of a scalar-tensorial gravity for the metric of an isolated self-gravitating superconducting cosmic string. These modifications are induced by an arbitrary coupling of a massless scalar field to the usual tensorial field in the gravitational Lagrangian. We derive the metric in the weak-field approximation and we analyse the behaviour of light in this spacetime. We end with some discussions.Comment: 12 pp, Latex, no figures, based on a talk given by M. E. X. Guimaraes at the COSMO 99, 27/9 to 02/10/99, ICTP, Trieste, I

The Effect of Health Care Entrepreneurship on Local Health: The Case of MedExpress in Appalachia

We test the hypothesis that the opening of an Urgent Care Center (UCC) has positive impacts on the local community. There are several mechanisms through which a UCC can have an impact: lower health care costs, emergency room decongestion, and improved access to medical information. We examine the entry of MedExpress into Appalachian counties between 2001 and 2013. Employing data from Health Resources Files, which provides information for all counties for specific years, we use Propensity Score Matching to create a year 2000 control group for the counties “treated” by MedExpress entry beginning in 2001. We then employ a standard difference-in-difference model on an unbalanced panel between 2001 and 2013. Our results suggest that MedExpress has a positive impact on different health outcome variables

Canonical transformation for stiff matter models in quantum cosmology

In the present work we consider Friedmann-Robertson-Walker models in the presence of a stiff matter perfect fluid and a cosmological constant. We write the superhamiltonian of these models using the Schutz's variational formalism. We notice that the resulting superhamiltonians have terms that will lead to factor ordering ambiguities when they are written as operators. In order to remove these ambiguities, we introduce appropriate coordinate transformations and prove that these transformations are canonical using the symplectic method.Comment: Revtex4 Class, 3 pages, No Figure

Lorentz-breaking effects in scalar-tensor theories of gravity

In this work, we study the effects of breaking Lorentz symmetry in scalar-tensor theories of gravity taking torsion into account. We show that a space-time with torsion interacting with a Maxwell field by means of a Chern-Simons-like term is able to explain the optical activity in syncrotron radiation emitted by cosmological distant radio sources. Without specifying the source of the dilaton-gravity, we study the dilaton-solution. We analyse the physical implications of this result in the Jordan-Fierz frame. We also analyse the effects of the Lorentz breaking in the cosmic string formation process. We obtain the solution corresponding to a cosmic string in the presence of torsion by keeping track of the effects of the Chern-Simons coupling and calculate the charge induced on this cosmic string in this framework. We also show that the resulting charged cosmic string gives us important effects concerning the background radiation.The optical activity in this case is also worked out and discussed.Comment: 10 pages, no figures, ReVTex forma