MOND as the weak-field limit of an extended metric theory of gravity

We show that the Modified Newtonian Dynamics (MOND) regime can be fully recovered as the weak-field limit of a particular theory of gravity formulated in the metric approach. This is possible when Milgrom's acceleration constant is taken as a fundamental quantity which couples to the theory in a very consistent manner. As a consequence, the scale invariance of the gravitational interaction is naturally broken. In this sense, Newtonian gravity is the weak-field limit of general relativity and MOND is the weak-field limit of that particular extended theory of gravity.Comment: To appear in the proceedings of the 2011 Spanish Relativity Meeting (ERE2011) held in Madrid, Spain, 4 page

Non-relativistic Extended Gravity and its applications across different astrophysical scales

Using dimensional analysis techniques we present an extension of Newton's gravitational theory built under the assumption that Milgrom's acceleration constant is a fundamental quantity of nature. The gravitational force converges to Newton's gravity and to a MOND-like description in two different mass and length regimes. It is shown that a modification on the force sector (and not in the dynamical one as MOND does) is more convenient and can reproduce and predict different phenomena usually ascribed to dark matter at the non-relativistic level.Comment: 4 pages, 2 figures. To appear in the proceedings of the 2011 Spanish Relativity Meeting (ERE2011) held in Madrid, Spai

Música y deconstrucción

Música y, con ella, una serie de presupuestos asociados, sin los cuales el acto musical entendido como tal no puede llevarse a cabo: 1. Delimitación de lo musical dentro de una esfera previamente definida, cerrando una posible permeabilidad político-social de su discurso. 2. Ordenación de su material de acuerdo con unos modelos jerárquicos impuestos. 3. Separación categorial de los elementos musicales, que niegan la posibilidad de existencia de fenómenos intercategoriales que cuestionen la arbitrariedad de las categorías fijadas. 4. Y como último y quizá también primer presupuesto: continuismo en la definición de lo que la música debe y no debe ser. Tomando como referencia conceptual -pero, en ningún caso, operativa- la deconstrucción iniciada por Derrida a la que son sometidos presupuestos filosófico-textuales de origen similar a los musicales, el presente texto trata de abordar si y, en caso afirmativo, cómo diversos dogmas, estrategias de poder e invisibilidades pueden hacerse visibles a través de la deconstrucción de los presupuestos musicales en los que se inscriben; todo ello, tratando de evitar la imposible y contradictoria extrapolación de constructos filosóficos al ámbito de lo artístico, en aras de una observación y deconstrucción de la problemática musical desde dentro de su propia realidad, si es que realmente podemos hablar de «una».Music: here, a set of presupposed characteristics is intended, without which the «Musical Act» cannot exist: 1. Delimitation of the musical act within a pre-defined realm, aborting the potential socio-political permeation of its discourse. 2. Arrangement of the musical material according to imposed hierarchical models. 3. Categorical separation of differing elements, thereby preventing the existence of inbetween phenomena which might otherwise call into question the arbitrary nature of the fixed categories. 4. And last, but not least, continuity in the definition of what music should and should not be. Taking Derrida's deconstructive procedures as a conceptual -but nonetheless operative- reference, to which philosophical and textual assumptions sharing similar origins with the musical assumptions are exposed, the present article contemplates if and how dogmas, power strategies, and indiscernable elements can be made apparent through the deconstruction of musical assumptions to which they subscribe; everything avoiding the impossible and contradictory extrapolation of philosophical constructs into the realm of the art, in pro of an observation and deconstruction of the musical problematic within its own reality, if we really can speak about «one»

Una comparación de algoritmos basados en trayectoria granular para el problema de localización y ruteo con flota heterogénea (LRPH)

Indexación: Scopus.We consider the Location-Routing Problem with Heterogeneous Fleet (LRPH) in which the goal is to determine the depots to be opened, the customers to be assigned to each open depot, and the corresponding routes fulfilling the demand of the customers and by considering a heterogeneous fleet. We propose a comparison of granular approaches of Simulated Annealing (GSA), of Variable Neighborhood Search (GVNS) and of a probabilistic Tabu Search (pGTS) for the LRPH. Thus, the proposed approaches consider a subset of the search space in which non-favorable movements are discarded regarding a granularity factor. The proposed algorithms are experimentally compared for the solution of the LRPH, by taking into account the CPU time and the quality of the solutions obtained on the instances adapted from the literature. The computational results show that algorithm GSA is able to obtain high quality solutions within short CPU times, improving the results obtained by the other proposed approaches.https://revistas.unal.edu.co/index.php/dyna/article/view/55533/5896