Cosmic Ray Small Scale Anisotropies and Local Turbulent Magnetic Fields

Cosmic ray anisotropy has been observed in a wide energy range and at different angular scales by a variety of experiments over the past decade. However, no comprehensive or satisfactory explanation has been put forth to date. The arrival distribution of cosmic rays at Earth is the convolution of the distribution of their sources and of the effects of geometry and properties of the magnetic field through which particles propagate. It is generally believed that the anisotropy topology at the largest angular scale is adiabatically shaped by diffusion in the structured interstellar magnetic field. On the contrary, the medium- and small-scale angular structure could be an effect of non-diffusive propagation of cosmic rays in perturbed magnetic fields. In particular, a possible explanation of the observed small-scale anisotropy observed at TeV energy scale, may come from the effect of particle scattering in turbulent magnetized plasmas. We perform numerical integration of test particle trajectories in low-$\beta$ compressible magnetohydrodynamic turbulence to study how the cosmic rays arrival direction distribution is perturbed when they stream along the local turbulent magnetic field. We utilize Liouville's theorem for obtaining the anisotropy at Earth and provide the theoretical framework for the application of the theorem in the specific case of cosmic ray arrival distribution. In this work, we discuss the effects on the anisotropy arising from propagation in this inhomogeneous and turbulent interstellar magnetic field.Comment: 14 pages, 7 figures. Accepted for publication in Ap

Identification and quantification of drivers of forest degradation in tropical dry forests: a case study in Western Mexico

The intensity of forest degradation is linked to landowners' decisions on management of their shifting cultivation systems. Understanding the processes involved in this land use type is therefore essential for the design of sustainable forest management practices. However, knowledge of the processes and patterns of forest transition that result from this practice is extremely limited. In this study, we used spatially-explicit binary logistic regression to study the proximate factors that relate to forest degradation by combining biophysical and socio-economic variables. Our study region is within the Ayuquila Basin, in Western Mexico, a typical fragmented tropical dry forest landscape dominated by shifting cultivation. Through a survey and semi-structured interviews with community leaders, we obtained data on the forest resources and on the uses that people make of them. Detailed forest cover maps for 2004 and 2010 were produced from high-resolution SPOT 5 data, and ancillary geographical data were used to extract spatial variables. The degree of social marginalization of each community and the ratio of forest area to population size were the main factors positively correlated with the probability of the occurrence of forest degradation. Livestock management and use of fence posts by the communities were also positively associated with forest degradation. Among biophysical factors, forest degradation is more likely to occur in flatter areas. We conclude that local drivers of forest degradation include both socioeconomic and physical variables and that both of these factors need to be addressed at the landscape level while developing measures for activities related to REDD+. (C) 2015 Elsevier Ltd. All rights reserved

La migración internacional en Costa Rica: estado actual y consecuencias

En la actualidad los flujos migratorios internacionales obedecen a las desigualdades existentes en los procesos de desarrollo económico y social de los países, a los efectos de políticas para atender dichos procesos, a conflictos sociopolíticos y situaciones de emergencia, todo lo cual afecta la sobrevivencia de las poblaciones más vulnerables. La estimación de la migración internacional es una necesidad cada vez más prioritaria a escala mundial y en la región latinoamericana en particular, dadas las características del contexto de globalización y desregulación de mercados imperante, con la consecuente mayor movilidad de recursos y población entre países. La agudización de la movilidad internacional de población hacia Costa Rica en la década del noventa y la ausencia de un censo nacional desde 1984, despertaron gran interés por el estudio de este fenómeno que tiene presencia histórica en el país, y generaron expectativas mayores sobre los resultados que arrojaría el Censo Nacional 2000. De las variables demográficas que determinan el crecimiento de la población, la migración internacional es la que presenta mayor dificultad para su captación y estimación, ya que una persona puede experimentar un número casi indeterminado de movimientos y cada movimiento involucrar al menos dos lugares o zonas (origen y destino). La definición tradicional de migración, utilizada y recomendada por Naciones Unidas, establece que la migración internacional es el cambio de país de la residencia habitual. De manera que un migrante internacional será aquella persona que en un determinado momento se encuentra residiendo en un país distinto al de nacimiento o al de residencia anterior (CELADE e IUSSP, 1985). Lo anterior implica una primera limitación, toda vez que esta definición operacional capta sólo movimientos o cambios permanentes de residencia, mientras que lo que parece estar predominando en el ámbito nacional y en la región latinoamericana, es una alta movilidad de la población. La movilidad espacial alude a un fenómeno más complejo, que involucra distintas modalidades de desplazamientos poblacionales, respondiendo a una multidimensionalidad de causas y afectando a un espacio de vida más amplio que sólo un origen y un destino. Entre las modalidades de movilidad, resaltan aquellos traslados de un país a otro por motivos estacionales o temporales –para realizar algún tipo de trabajo– así como los originados por turismo y estudio; lo cual provoca otras variantes de migración internacional como las poblaciones en tránsito, la residencia múltiple, el pluriempleo (traslados circulares o pendulares) y las migraciones de retorno. Esto establece retos a la definición y operacionalización de la migración internacional y, sobre todo, a las fuentes de información para su estudio: registros de entradas y salidas, censos y encuestas (Barquero,2000)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Sociales::Centro Centroamericano de Población (CCP

Broadcasting scalable video with generalized spatial modulation in cellular networks

This paper considers the transmission of scalable video via broadcast and multicast to increase spectral and energy efficiency in cellular networks. To address this problem, we study the use of generalized spatial modulation (GSM) combined with non-orthogonal hierarchical M-QAM modulations due to the capability to exploit the potential gains of large scale antenna systems and achieve high spectral and energy efficiencies. We introduce the basic idea of broadcasting/multicasting scalable video associated to GSM, and discuss the key limitations. Non-uniform hierarchical QAM constellations are used for broadcasting/multicasting scalable video while user specific messages are carried implicitly on the indexes of the active transmit antennas combinations. To deal with multiple video and dedicated user streams multiplexed on the same transmission, an iterative receiver with reduced complexity is described. 5G New Radio (NR) based link and system level results are presented. Two different ways of quadruplicating the number of broadcasting programs are evaluated and compared. Performance results show that the proposed GSM scheme is capable of achieving flexibility and energy efficiency gain over conventional multiple input multiple output (MIMO) schemes.info:eu-repo/semantics/publishedVersio

Predictive capacity of boar sperm morphometry and morphometric sub-populations on reproductive success after artificial insemination

The aim of the study was to compare the morphometric features of sperm head size and shape from the Pietrain line and the Duroc × Pietrain boar crossbred terminal lines, and to evaluate their relationship with reproductive success after artificial insemination of sows produced from crossbreeding the York, Landrace and Pietrain breeds. Semen samples were collected from 11 sexually mature boars. Only ejaculates with greater than 70% motility rate and <15% of abnormal sperm were used for artificial inseminations (AI) and included in the study. Samples were analyzed using an ISAS®v1 computer-assisted sperm analysis system for eight morphometric parameters of head shape and size (CASA-Morph). Sub-populations of morphometric ejaculates were characterized using multivariate procedures, such as principal component (PC) analysis and clustering methods (k-means model). Four different ejaculate sub-populations were identified from two PCs that involved the head shape and size of the spermatozoa. The discriminant ability of the different morphometric sperm variables to predict sow litter size was analyzed using a receiver operating characteristics (ROC) curve analysis. Sperm head length, ellipticity, elongation, and regularity showed significant predictive capacity on litter size (0.59, 0.59, 0.60, and 0.56 area under curve (AUC), respectively). The morphometric sperm sub-populations were not related to sow litter size

Increasing particle concentration enhances particle penetration depth but slows down liquid imbibition in thin fibrous filters

The transport of particles within thin, porous media is a complex process which received growing attention due to its applications in filtration, printing and microfluidics devices. The effect of particles on liquid imbibition and particle clogging can reduce the performance and lifetime of these applications. However, these processes are still not clearly understood and are challenging to investigate. The goal of this study is to increase our understanding about the effect of particle concentration on the imbibition process in thin fibrous membrane filters. In this study, an Ultra-Fast Imaging NMR method is used to study the particle penetration inside nylon membrane filters for particle suspensions with varying particle concentrations (C0). The measurements revealed that increasing the particle concentration increases the particle penetration depth S(t) as governed by a Langmuir isotherm given by S(t)=l(t)(1+κC0)/1+κ(C0+Cb,m), with Cb,m the bound particles and κ the binding constant. Secondly, in droplet penetration, particles slow down liquid penetration in a Darcy like manner where effect on viscosity (η) and surface tension (σ) determine the penetration speed rather than changes within permeability (K0). The final liquid front (l), scaled according to l2∝σt/η. The particle penetration depths were verified using scanning electron microscopy images.</p

Magnetite-latex nanoparticle motion during capillary uptake in thin, porous layers studied with UFI‐NMR

The transport of nanoparticles in porous media has received growing attention in the last decades due to environmental concerns in, for example, the printing industry, filtration, and transport of pollutants. Experimental studies on the imbibition of particle dispersions in porous media with sufficiently high spatial and temporal resolution are still challenging. This study shows how Ultra-Fast Imaging (UFI) NMR is an ideal tool for studying Fe3O4-latex particles penetration with a temporal resolution of 15 ms and spatial resolution of 18 µm. In the first part, it is shown that a calibration curve between the UFI‐NMR signal intensity and the particle concentration exists. In the second part, UFI‐NMR is used to study the penetration of a particles inside a thin nylon membrane during capillary uptake, which revealed liquid-particle front splitting and an inhomogeneous buildup of the particle concentration. Both the liquid-particle front splitting and inhomogeneous build up could be verified by Scanning Electron Microscopy. Our method allows to determine particle concentration profiles during capillary uptake within thin, porous media. Therefore, the technique can be easily extended to study particle penetrations in a wide variety of systems such thin interfaces, biomaterials, films, and filter media.</p

Estrategias para la formación de profesorado en Objetivos de Desarrollo Sostenible y su implementación transversal en la asignatura de Macroeconomía.

Formación del profesorado en Educación para el Desarrollo y Objetivos de Desarrollo Sostenible e Implementación DidácticaLa estructura y contenidos que ofrecen los Objetivos de Desarrollo Sostenible (ODS) presentan el marco conceptual que facilita el análisis crítico y la comprensión de las causas de la pobreza y desigualdad. En este sentido, aunque los ODS puedan recibir críticas por no ser un instrumento eficaz para alcanzar los propósitos para los que han sido diseñados, constituyen una referencia útil para los estudiantes de grado universitario y un recurso didáctico eficaz para cumplir simultáneamente con la implementación de los contenidos de la asignatura y la introducción de la Educación para el Desarrollo y para la Ciudadanía Global (EDCG) en la Universidad. Esta educación, aplicada transversalmente, permite al alumnado comprender mejor el mundo que le rodea, promueve una ciudadanía global, crítica y comprometida para actuar y abordar las causas fundamentales de la injusticia, así como crear y transformar un futuro más justo y sostenible para todos. Este artículo reflexiona sobre los resultados de un proyecto de innovación docente de tres años de duración en el que se integraron los contenidos de los ODS en un programa tradicional de macroeconomía. El resultado obtenido fue que, a la vez que proporcionó formación en EDCG a profesores universitarios en ejercicio, incluyó en la actividad docente el análisis de los efectos que determinadas decisiones económicas y políticas pueden generar en dimensiones sociales, medioambientales y económicas. Así, bajo un enfoque humanista, en la asignatura de macroeconomía se examinaron y valoraron algunas tendencias económicas y sociales teniendo en cuenta los efectos secundarios que estas acciones pueden producir, entre ellos, la generación de pobreza e injusticia social.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Plan Propio de Investigación de la UM