Tafonomía multiservicio. valvas, basura y palimpsestos flotantes

We discuss the importance of widening the scope of taphonomy, arguing that it is critical to study of different classes of materials within this framework. We introduce several examples related to the deposition of marine shells and garbage. In particular, we focus on debris generated by tsunamis.Se presenta una discusión acerca de la importancia de ampliar el campo de la tafonomía, considerando distintas clases de materiales. Se presentan varios ejemplos, relacionados con la depositación de valvas marinas y el estudio de la basura en diferentes contextos. Se desarrolla en particular el caso de los desechos derivados de la acción de tsunamis.Fil: Borrero, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Multidisciplinario de Historia y Ciencias Humanas; Argentin

Some global causal properties in certain classes of spacetimes

Fecha de lectura de Tesis: 13 de junio 2018.Causality is a specific tool of Lorentzian Geometry, with a clear physical motivation, which has played a central role in proving important theorems about the global structure of spacetimes. Causality conditions are classified in terms of the so called causal ladder, whose steps determine how these conditions are logically related. Each of these levels presents some specific properties, standing out at the top one, which is occupied by the condition of global hyperbolicity. In fact, it is believed that any physical spacetime must be globally hyperbolic (roughly, this is the content of the strong cosmic censorship hypothesis), and then, will admit a global splitting in terms of a Cauchy surface, on which the Einstein equations can be posed as an initial value problem. Causality theory also provides a boundary construction for the very general class of strongly causal spacetimes, namely, the so-called causal boundary or just c-boundary. This boundary is less commonly used in General Relativity than the conformal one, because some classical spacetimes present a simple conformal boundary with quite a few of interesting properties. However, beyond such examples, there is no a general way to ensure that the conformal boundary exists. In contraposition, the c-boundary is not only conformally invariant but also intrinsic and it can be computed systematically; such properties make it more suitable in general situations. This includes the holographic principle, which original started at a restricted situation concerning the conformal boundary of Anti-de Sitter spacetime for the AdS/CFT correspondence. The main purpose of this memory is to improve our knowledge about the c-boundary and the causal ladder of some important classes of spacetimes

Cosmological parameter inference with Bayesian statistics

Bayesian statistics and Markov Chain Monte Carlo (MCMC) algorithms have found their place in the field of Cosmology. They have become important mathematical and numerical tools, especially in parameter estimation and model comparison. In this paper, we review some fundamental concepts to understand Bayesian statistics and then introduce MCMC algorithms and samplers that allow us to perform the parameter inference procedure. We also introduce a general description of the standard cosmological model, known as the $\Lambda$CDM model, along with several alternatives, and current datasets coming from astrophysical and cosmological observations. Finally, with the tools acquired, we use an MCMC algorithm implemented in python to test several cosmological models and find out the combination of parameters that best describes the Universe.Comment: 30 pages, 17 figures, 5 tables; accepted for publication in Universe; references adde

On the Chow rings of classifying spaces for classical groups

We show how the stratification method, introduced by Vezzosi in his study of PGL_3, provides a unified approach to the known computations of the Chow rings of the classifying spaces of GL_n, SL_n, Sp_n, O_n and SO_n.Comment: 24 page