759 research outputs found
The Minimal Geometric Deformation Approach: a brief introduction
We review the basic elements of the Minimal Geometric Deformation approach in
details. This method has been successfully used to generate brane-world
configurations from general relativistic perfect fluid solutions.Comment: Brief review; minor corrections; references adde
Anisotropic solutions by gravitational decoupling
We investigate the extension of isotropic interior solutions for static
self-gravitating systems to include the effects of anisotropic spherically
symmetric gravitational sources by means of the gravitational decoupling
realised via the minimal geometric deformation approach. In particular, the
matching conditions at the star surface with the outer Schwarzschild space-time
are studied in great details, and we describe how to generate, from a single
physically acceptable isotropic solution, new families of anisotropic solutions
whose physical acceptability is also inherited from their isotropic parent.Comment: 20 pages, 4 figures; references and typos corrected; final version to
match the EPJC versio
A causal Schwarzschild-de Sitter interior solution by gravitational decoupling
We employ the minimal geometric deformation approach to gravitational
decoupling (MGD- decoupling) in order to build an exact anisotropic version of
the Schwarzschild interior solution in a space-time with cosmological constant.
Contrary to the well-known Schwarzschild interior, the matter density in the
new solution is not uniform and possesses subluminal sound speed. It therefore
satisfies all standard physical requirements for a candidate astrophysical
object.Comment: 15 pages, 6 figure
Non-uniform Braneworld Stars: an Exact Solution
The first exact interior solution to Einstein's field equations for a static
and non-uniform braneworld star with local and non-local bulk terms is
presented. It is shown that the bulk Weyl scalar is always
negative inside the stellar distribution, in consequence it reduces both the
effective density and the effective pressure. It is found that the anisotropy
generated by bulk gravity effect has an acceptable physical behaviour inside
the distribution. Using a Reissner-N\"{o}rdstrom-like exterior solution, the
effects of bulk gravity on pressure and density are found through matching
conditions.Comment: 22 pages, 3 figures, version to be published in International Journal
of Modern Physics D (IJMPD
The Other September 11th: El Mercurio Media Coverage after the Chilean Coup of 1973
This thesis provides an exploratory overview of the role the El Mercurio newspaper played along with the military after the Chilean coup of 1973. The study reviews the contents of the newspaper’s front pages, including their coverage of the events during the coup. The thesis will show how the paper revisited its coverage each year on the September 11th anniversary, beginning with the years dominated by the military government, from 1973 through 1990, and continuing through the transition to democracy, from 1991 through 2007. The primary method used in the course of this examination is a content analysis, which will determine how propaganda was used during and after the coup, and to show media bias in favor of the government through the use of language used images conveyed by the conservative faction during the dictatorship and even later during Chile’s transition to democracy
Stable Solutions of the Double Compactified D=11 Supermembrane Dual
The hamiltonian formulation of the supersymmetric closed 2-brane dual to the
double compactified D=11 closed supermembrane is presented. The formulation is
in terms of two U(1) vector fields related by the area preserving constraint of
the SUSY 2-brane. Stable solutions of the field equations, which are local
minima of the hamiltonian, are found. In the semiclassical approximation around
the stable solutions the action becomes the reduction of D=10 Super-Maxwell to
the worldvolume. The solutions carry RR charges as a type of magnetic charges
associated with the worldvolume vector field. The geometrical interpretation of
the solution in terms of U(1) line bundles over the worldvolume is obtained.Comment: 14 pages, late
Integración de procesos de negocio basados en servicios Web: Coreografía y satisfacción de restricciones
Los procesos de negocio en ocasiones necesitan funcionalidades adicionales que pueden alcanzarse empleando servicios del mismo dominio o de uno externo. Durante este procedimiento, los servicios web involucrados deben integrarse, de tal forma que sus funcionalidades individuales generen un comportamiento global. La coreografía de servicios web controla la secuencia de las interacciones entre los servicios durante el proceso de integración. Este artículo presenta una aproximación al modelado basado en restricciones de la coreografía de servicios web, a fin de lograr su automatización
On the Substitution of Identicals in Counterfactual Reasoning
It is widely held that counterfactuals, unlike attitude ascriptions, preserve the referential transparency of their constituents, i.e., that counterfactuals validate the substitution of identicals when their constituents do. The only putative counterexamples in the literature come from counterpossibles, i.e., counterfactuals with impossible antecedents. Advocates of counterpossibilism, i.e., the view that counterpossibles are not all vacuous, argue that counterpossibles can generate referential opacity. But in order to explain why most substitution inferences into counterfactuals seem valid, counterpossibilists also often maintain that counterfactuals with possible antecedents are transparency‐preserving. I argue that if counterpossibles can generate opacity, then so can ordinary counterfactuals with possible antecedents. Utilizing an analogy between counterfactuals and attitude ascriptions, I provide a counterpossibilist‐friendly explanation for the apparent validity of substitution inferences into counterfactuals. I conclude by suggesting that the debate over counterpossibles is closely tied to questions concerning the extent to which counterfactuals are more like attitude ascriptions and epistemic operators than previously recognized
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