Long-range correlations and trends in Colombian seismic time series

We study long-range correlations and trends in time series extracted from the data of seismic events occurred from 1973 to 2011 in a rectangular region that contains mainly all the continental part of Colombia. The long-range correlations are detected by the calculation of the Hurst exponents for the time series of interevent intervals, separation distances, depth differences and magnitude differences. By using a modification of the classical $R/S$ method that has been developed to detect short-range correlations in time series, we find the existence of persistence for all the time series considered except for magnitude differences. We find also, by using the $DFA$ until the third order, that the studied time series are not influenced by trends. Additionally, an analysis of the Hurst exponent as a function of the number of events in the time and the maximum window size is presented.Comment: 21 pages, 6 figures, 2 figures added, types corrected, accepted to be published in Physica

The Odyssey Approach for Optimizing Federated SPARQL Queries

Answering queries over a federation of SPARQL endpoints requires combining data from more than one data source. Optimizing queries in such scenarios is particularly challenging not only because of (i) the large variety of possible query execution plans that correctly answer the query but also because (ii) there is only limited access to statistics about schema and instance data of remote sources. To overcome these challenges, most federated query engines rely on heuristics to reduce the space of possible query execution plans or on dynamic programming strategies to produce optimal plans. Nevertheless, these plans may still exhibit a high number of intermediate results or high execution times because of heuristics and inaccurate cost estimations. In this paper, we present Odyssey, an approach that uses statistics that allow for a more accurate cost estimation for federated queries and therefore enables Odyssey to produce better query execution plans. Our experimental results show that Odyssey produces query execution plans that are better in terms of data transfer and execution time than state-of-the-art optimizers. Our experiments using the FedBench benchmark show execution time gains of at least 25 times on average.Comment: 16 pages, 10 figure

A new method for the solution of the Schrodinger equation

We present a new method for the solution of the Schrodinger equation applicable to problems of non-perturbative nature. The method works by identifying three different scales in the problem, which then are treated independently: An asymptotic scale, which depends uniquely on the form of the potential at large distances; an intermediate scale, still characterized by an exponential decay of the wave function and, finally, a short distance scale, in which the wave function is sizable. The key feature of our method is the introduction of an arbitrary parameter in the last two scales, which is then used to optimize a perturbative expansion in a suitable parameter. We apply the method to the quantum anharmonic oscillator and find excellent results.Comment: 4 pages, 4 figures, RevTex

Mejora metodológica de las enseñanzas en el EEES en el caso de las materias pedagógicas

The following document is the final report of an institutional project that the Department of Teaching and Theory of Education in 2009 introduced to the Office of European convergence aimed at boosting teacher quality improvement and renewal of the teaching methodology in the Teacher Training Degree. The activities developed by the team of teachers are here described in order to revise the aims and features of the different pedagogical subjects included in the degree of Child Education and Primary Education. We also include the indicators used to make a follow-up of the activities. To conclude, we include the results obtained in the opinion survey about the changes this project introduces in the teaching of this degree. In addition, we show here a little sample of the study of the profile of teaching professionals carried out by the Secondary Education teamworkEste trabajo reúne los principales resultados de un proyecto institucional que el Departamento de Didáctica y Teoría de la educación presentó en el año 2009 a la Oficina de Convergencia europea destinado a impulsar la mejora de la calidad docente y la renovación metodológica de las enseñanzas en las titulaciones de maestro .Se describen las actividades realizadas por el equipo docente a fin de revisar los objetivos y características de la materias pedagógicas en los Grados de Maestro de Infantil y Maestro de Primaria así como los indicadores de seguimiento de esas actividades .Para terminar se incluyen los resultados obtenidos en la encuesta de opinión sobre los cambios que introduce este proyecto en las enseñanzas de Grado. Así mismo, se aporta una pequeña muestra del equipo de trabajo de Educación Secundaria sobre el estudio del perfil profesional docente

Double Threefold Degeneracies for Active and Sterile Neutrinos

We explore the possibility that the 3 active (doublet) neutrinos have nearly degenerate masses which are split only by the usual seesaw mechanism from 3 sterile (singlet) neutrinos in the presence of a softly broken $A_4$ symmetry. We take the unconventional view that the sterile neutrinos may be light, i.e. less than 1 keV, and discuss some very interesting and novel phenomenology, including a connection between the LSND neutrino data and solar neutrino oscillations.Comment: 8 pages, no figur