1,157 research outputs found
Background-independent charges in Topologically Massive Gravity
We construct background-independent Noether charges in Topologically Massive
Gravity with negative cosmological constant using its first-order formulation.
The procedure is carried out by keeping track of the surface terms in the
variation of the action, regardless the value of the gravitational Chern-Simons
coupling . In particular, this method provides a definition of conserved
quantities for solutions at the chiral point ( is the AdS
radius) that contain logarithmic terms (Log Gravity). It is also shown that the
charge formula gives a finite result for warped AdS black holes without the
need for any background-substraction procedure.Comment: 23 pages; appendix and a few references added; final version for JHE
Synthesis, thermal behavior, and aggregation in aqueous solution of poly(methyl methacrylate)-b-poly(2-hydroxyethyl methacrylate)
Indexación: ScieloABSTRACT
Amphiphilic block copolymers of poly(methyl methacrylate) PMMA and poly(2-hidroxyethyl methacrylate) PHEMA were synthesized by a two-step atom transfer radical polymerization (ATRP). Copolymers with various degrees of polymerization and different relative block sizes were obtained. The structure of the resulting polymers have been characterized and verified by FT-IR and 1H-NMR, molecular weight were determined by size exclusion chromatography analyses. The thermal properties of these polymers were investigated by differential scanning calorimetry DSC and thermogravimetric analysis TGA. The glass transition temperature of mono halogenated PMMA increases from 116 °C to 123 °C with increasing molecular weight, whereas the glass transition temperature of block copolymers depends slightly on polymer structure. The derivatives of TGA curves indicate that thermal degradation occurs in one stage. The self-assembly of PMMA-b-PHEMA in aqueous solution have been investigated by fluorescence probing methods. The critical micelle concentrations are in the range 10-6 - 10-7 M. The micropolarity sensed by pyrene is higher than in aggregates formed by block copolymers based on polystyrene.
Keywords: Block copolymers, glass transition temperature, thermogravimetric analysis, critical micelle concentration, fluorescence probing methods
Star Wars Episode III: Revenge of the Sith
This is a review of Star Wars Episode III: Revenge of the Sith (2005)
La participación de indocumentados mexicanos en Estados Unidos: Un modelo tobit de ecuaciones simultáneas
Falso aneurisma tras fractura diafisaria de fémur: Tratamiento mediante embolización
Un falso aneurisma es una complicación rara de una fractura de la diáfisis femoral. Se presenta un caso que fue diagnosticado tardíamente debido a la ausencia de sintomatología típica. Se discuten la etiología, profilaxis, diagnóstico y posibilidades terapéuticas; destacándose la novedad del diagnóstico y tratamiento mediante arteriografía y embolización selectiva.A false aneurysm following a closed femoral-shaft fracture is a rare complication. The author report a case that was lately diagnosed because of the absence of typical symptomatology. Aetiology, prophylaxis, diagnosis and treatment are discussed, emphasizing the new method of diagnosis and treatment by arteriography and selective embolism
Hamilton-Jacobi Counterterms for Einstein-Gauss-Bonnet Gravity
The on-shell gravitational action and the boundary stress tensor are
essential ingredients in the study of black hole thermodynamics. We employ the
Hamilton-Jacobi method to calculate the boundary counterterms necessary to
remove the divergences and allow the study of the thermodynamics of
Einstein-Gauss-Bonnet black holes.Comment: 21 pages, LaTe
Posterior distribution of nondifferentiable functions
This paper examines the asymptotic behavior of the posterior distribution of a possibly nondifferentiable function g(θ), where θ is a finite-dimensional parameter of either a parametric or semiparametric model. The main assumption is that the distribution of a suitable estimator θ^n, its bootstrap approximation, and the Bayesian posterior for θ all agree asymptotically. It is shown that whenever g is locally Lipschitz, though not necessarily differentiable, the posterior distribution of g(θ) and the bootstrap distribution of g(θ^n) coincide asymptotically. One implication is that Bayesians can interpret bootstrap inference for g(θ) as approximately valid posterior inference in a large sample. Another implication—built on known results about bootstrap inconsistency—is that credible intervals for a nondifferentiable parameter g(θ) cannot be presumed to be approximately valid confidence intervals (even when this relation holds true for θ)
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