Search results for "matemática"
showing 10 items of 434 documents
Minimum main sequence mass in quadratic Palatini f ( R ) gravity
2019
General relativity yields an analytical prediction of a minimum required mass of roughly ∼0.08-0.09 M for a star to stably burn sufficient hydrogen to fully compensate photospheric losses and, therefore, to belong to the main sequence. Those objects below this threshold (brown dwarfs) eventually cool down without any chance to stabilize their internal temperature. In this work we consider quadratic Palatini f(R) gravity and show that the corresponding Newtonian hydrostatic equilibrium equation contains a new term whose effect is to introduce a weakening/strengthening of the gravitational interaction inside astrophysical bodies. This fact modifies the general relativity prediction for this m…
Gamificación en educación superior. Una escape room para el aula de matemáticas
2020
[ES] De unos años a esta parte, el perfil de nuestros estudiantes ha cambiado de manera considerable. Esto hace que, de manera complementaria a las clases magistrales, los profesores poco a poco debamos adaptarnos a las nuevas generaciones, mucho más tecnológicas que años atrás. Una de las maneras de aumentar la motivación y la participación de los estudiantes en nuestra asignatura es el planteamiento y la realización de diferentes actividades de manera que esto nos ayude también a desarrollar materiales que se adecuen al mayor número de alumnos posible. El objetivo general del presente artículo es utilizar la gamificación como herramienta docente en el aula. En concreto, proponemos el uso …
Improving the Representativeness of a Simple Random Sample: An Optimization Model and Its Application to the Continuous Sample of Working Lives
2020
This paper proposes an optimization model for selecting a larger subsample that improves the representativeness of a simple random sample previously obtained from a population larger than the population of interest. The problem formulation involves convex mixed-integer nonlinear programming (convex MINLP) and is, therefore, NP-hard. However, the solution is found by maximizing the size of the subsample taken from a stratified random sample with proportional allocation and restricting it to a p-value large enough to achieve a good fit to the population of interest using Pearson&rsquo
Canciones infantiles para aprender matemáticas
2021
Resumen basado en el de la publicación Resumen en inglés Web del proyecto que se describe: http://guiadecancionesmatematicas.piojosoft.es/ Monográfico con el título: Aprendizaje-servicio (ApS): aprender desde la responsabilidad social La música es un recurso para la enseñanza y el aprendizaje de los contenidos matemáticos para la etapa de Educación Infantil y los primeros cursos de Educación Primaria. Se describe un estudio que consistió en realizar una búsqueda, selección y categorización de canciones que son una herramienta para facilitar el trabajo de los docentes en la enseñanza y aprendizaje de los contenidos matemáticos. El producto obtenido de tal investigación son 98 canciones distr…
Light ring images of double photon spheres in black hole and wormhole spacetimes
2022
The silhouette of a black hole having a critical curve (an unstable bound photon orbit) when illuminated by an optically thin accretion disk whose emission is confined to the equatorial plane shows a distinctive central brightness depression (the shadow) whose outer edge consists of a series of strongly lensed, self-similar rings superimposed with the disk's direct emission. While the size and shape of the critical curve depend only on the background geometry, the pattern of bright and dark regions (including the size and depth of the shadow itself) in the image is strongly influenced by the (astro)physics of the accretion disk. This aspect makes it difficult to extract clean and clear obse…
Structure and stability of traversable thin-shell wormholes in Palatini f(R) gravity
2020
We study the structure and stability of traversable wormholes built as (spherically symmetric) thin shells in the context of Palatini f(R) gravity. Using a suitable junction formalism for these theories we find that the effective number of degrees of freedom on the shell is reduced to a single one, which fixes the equation of state to be that of massless stress-energy fields, contrary to the general relativistic and metric f(R) cases. Another major difference is that the surface energy density threading the thin shell, needed in order to sustain the wormhole, can take any sign and may even vanish, depending on the desired features of the corresponding solutions. We illustrate our results by…
Combinatorics of the SU(2) black hole entropy in loop quantum gravity
2009
We use the combinatorial and number-theoretical methods developed in previous works by the authors to study black hole entropy in the new proposal put forth by Engle, Noui, and Perez. Specifically, we give the generating functions relevant for the computation of the entropy and use them to derive its asymptotic behavior, including the value of the Immirzi parameter and the coefficient of the logarithmic correction.
Geometric inequivalence of metric and Palatini formulations of General Relativity
2020
Projective invariance is a symmetry of the Palatini version of General Relativity which is not present in the metric formulation. The fact that the Riemann tensor changes nontrivially under projective transformations implies that, unlike in the usual metric approach, in the Palatini formulation this tensor is subject to a gauge freedom, which allows some ambiguities even in its scalar contractions. In this sense, we show that for the Schwarzschild solution there exists a projective gauge in which the (affine) Kretschmann scalar, K≡R R , can be set to vanish everywhere. This puts forward that the divergence of curvature scalars may, in some cases, be avoided by a gauge transformation of the …
La Modelización como herramienta de evaluación competencial
2016
[EN] The concept of competency has become more and more important in our educational system, partly due because of external tests assessing educational quality, as PISA, highlight the need not only to introduce methodological changes in the teaching of mathematics in the Secondary education, but also to design new tools in order to develop mathematical competence, understood as the ability of our students to mathematize real life situations. In this thesis we want to study the role that modelling tasks can play in the development of mathematical competency, and, particularly, in problem solving. For this aim, we have designed a series of modelling tasks based on three different perspectives…
Vector-valued sequences and multipliers
2015
El texto que se presenta trata de establecer un marco teórico en el que poder manejar dos nuevos conceptos (extensión de conceptos ya conocidos): los multiplicadores por coeficientes a través de una aplicación bilineal y el producto proyectivo tensorial de Hadamard. Ambos espacios se ven siempre como espacios de sucesiones a valores vectoriales, esto es, en un espacio de Banach cualquiera. Posteriormente, se estudia la relación entre ellos y se aportan algunos ejemplos. El punto de partida del proyecto son las clases de espacios introducidas por O.Blasco y M. Pavlovic en el trabajo "Coefficient multipliers on spaces of analytic functions" (Revista Mat. Iberoamericana, 2011) donde se formali…