Measuring the transition to homogeneity with photometric redshift surveys

We study the possibility of detecting the transition to homogeneity using photometric redshift catalogs. Our method is based on measuring the fractality of the projected galaxy distribution, using angular distances, and relies only on observable quantites. It thus provides a way to test the Cosmological Principle in a model-independent unbiased way. We have tested our method on different synthetic inhomogeneous catalogs, and shown that it is capable of discriminating some fractal models with relatively large fractal dimensions, in spite of the loss of information due to the radial projection. We have also studied the influence of the redshift bin width, photometric redshift errors, bias, non-linear clustering, and surveyed area, on the angular homogeneity index H2 ({\theta}) in a {\Lambda}CDM cosmology. The level to which an upcoming galaxy survey will be able to constrain the transition to homogeneity will depend mainly on the total surveyed area and the compactness of the surveyed region. In particular, a Dark Energy Survey (DES)-like survey should be able to easily discriminate certain fractal models with fractal dimensions as large as D2 = 2.95. We believe that this method will have relevant applications for upcoming large photometric redshift surveys, such as DES or the Large Synoptic Survey Telescope (LSST).Comment: 14 pages, 14 figure

Interacting dark sector with variable vacuum energy

We examine a cosmological scenario where dark matter is coupled to a variable vacuum energy while baryons and photons are two decoupled components for a spatially flat Friedmann-Robertson-Walker spacetime. We apply the $\chi^{2}$ method to the updated observational Hubble data for constraining the cosmological parameters and analyze the amount of dark energy in the radiation era. We show that our model fulfills the severe bound of $\Omega_{x}(z\simeq 1100)<0.009$ at the $2\sigma$ level, so it is consistent with the recent analysis that includes cosmic microwave background anisotropy measurements from the Planck survey, the Atacama Cosmology Telescope, and the South Pole Telescope along with the future constraints achievable by the Euclid and CMBPol experiments, and fulfills the stringent bound $\Omega_{x}(z\simeq 10^{10})<0.04$ at the $2\sigma$ level in the big-bang nucleosynthesis epoch.Comment: 5 pages,3 figures, 2 tables. (http://prd.aps.org/abstract/PRD/v88/i8/e087301

Osuna contra Lemos: la polémica del Panegyricus

La imprenta napolitana del Seicento produjo un notable número de publicaciones en castellano, en latín y en italiano que, pertenecientes al vasto campo de la literatura celebrativa, se presentan como documentos en donde las instancias del poder empapan la materia literaria: los textos se convierten en signos de institución, productos de una práctica escritoria que responde a ciertas exigencias del poder constituido. El artículo examina los más destacados ejemplos de este tipo de literatura durante el virreinato del VII Conde de Lemos (1610-1616) y compara la abundancia de esta práctica escritoria en ese arco de tiempo con la escasez que se manifiesta durante el virreinato del III Duque de Osuna (1616-1620). The Neapolitan printing from the Seicento produced a remarkable number of publications in Spanish, Latin and Italian belonging to the vast field of laudatory literature. They are presented as documents in which the corridors of power pervade the literary stuff; texts turn into signs of institution, into the products of the writing practice that responds to certain demands of the established power. The article explores the most salient examples of this kind of literature during the viceroyalty of the seventh Count of Lemos (1610-1616) and it also compares the plenty of this writing practice in this concrete lapse of time with the manifest scarcity during the viceroyalty of the third Duke of Osuna (1616- 1620)

Medición informal del p-valor mediante simulación

Existe un creciente reconocimiento de la importancia de desarrollar el razonamiento inferencial informal (RII) antes de aprender los conceptos formalmente. No obstante todavía hay poca investigación sobre su desarrollo en el aula en el nivel bachillerato (15-18 años). En situaciones informales, la principal dificultad es medir el p-valor de un estadístico, debido que no se tiene la noción de distribución muestral de forma natural. En el presente estudio se analiza el razonamiento de estudiantes de bachillerato para medir el p-valor de un estadístico al usar una aplicación dinámica que crea una distribución muestral empírica mediante la simulación computarizada. Se encuentra que la mayoría de los estudiantes miden el p-valor adecuadamente con ayuda de la simulación, lo que representa un cambio significativo en el RII

A Mathematical Model to Study the Meningococcal Meningitis

AbstractThe main goal of this work is to introduce a novel mathematical model to study the spreading of meningococcal meningitis. Specifically, it is a discrete mathematical model based on cellular automata where the population is divided in five classes: sus- ceptible, asymptomatic infected, infected with symptoms, carriers, recovered and died. It catches the individual characteristics of people in order to give a prediction of both the individual behavior, and whole evolution of population

A Highly Available Cluster of Web Servers with Increased Storage Capacity

Ponencias de las Decimoséptimas Jornadas de Paralelismo de la Universidad de Castilla-La Mancha celebradas el 18,19 y 20 de septiembre de 2006 en AlbaceteWeb servers scalability has been traditionally solved by improving software elements or increasing hardware resources of the server machine. Another approach has been the usage of distributed architectures. In such architectures, usually, file al- location strategy has been either full replication or full distribution. In previous works we have showed that partial replication offers a good balance between storage capacity and reliability. It offers much higher storage capacity while reliability may be kept at an equivalent level of that from fully replicated solutions. In this paper we present the architectural details of Web cluster solutions adapted to partial replication. We also show that partial replication does not imply a penalty in performance over classical fully replicated architectures. For evaluation purposes we have used a simulation model under the OMNeT++ framework and we use mean service time as a performance comparison metric.Publicad

Full two-photon downconversion of just a single photon

We demonstrate, both numerically and analytically, that it is possible to generate two photons from one and only one photon. We characterize the output two photon field and make our calculations close to reality by including losses. Our proposal relies on real or artificial three-level atoms with a cyclic transition strongly coupled to a one-dimensional waveguide. We show that close to perfect downconversion with efficiency over 99% is reachable using state-of-the-art Waveguide QED architectures such as photonic crystals or superconducting circuits. In particular, we sketch an implementation in circuit QED, where the three level atom is a transmon

Cattle marks similarity measure by shape distributions

This paper reports the investigation results addressed to design of a di­gital image processing method for automate the registration and control process of livestock marks according to Colombian regulations livestock sector. It allows automate the process of search and comparison required for livestock mark uniqueness assurance on a computer assisted system. First, a histogram is generated based on statistical distribution of geome­trical information, which permit to detect similarities between registered marks by means Minkowski-based metric. The results show that the method allows discriminating between images using a digital signature from a Shape Distribution the geometric structure reducing ambiguity and ensuring the uniqueness of registered marks. We show the results and make an analysis of system application.Este documento reporta los resultados de una investigación orientada hacia el diseño de un método de tratamiento de imágenes digitales para la automatización de los procesos de registro y control de marcas de ga­nado requeridas por las regulaciones del sector ganadero en Colombia. El método permite automatizar los procesos de búsqueda y de comparación necesarios para garantizar la unicidad de las marcas dentro de un sistema asistido por computadora. Se inicia con la generación de un histograma estimado de la geometría de la marca, lo que permite comparar y detec­tar similitudes entre las figuras previamente almacenadas, mediante una métrica de similitud basada en la distancia de Minkowski. Los resultados obtenidos indican que el método es adecuado para realizar un proceso de discriminación de dichas imágenes, reducir las ambigüedades y garantizar la unicidad de los registros. Los resultados obtenidos y un análisis de su aplicación son reportados