The origin of the LMC stellar bar: clues from the SFH of the bar and inner disk

We discuss the origin of the LMC stellar bar by comparing the star formation histories (SFH) obtained from deep color-magnitude diagrams (CMDs) in the bar and in a number of fields in different directions within the inner disk. The CMDs, reaching the oldest main sequence turnoffs in these very crowded fields, have been obtained with VIMOS on the VLT in service mode, under very good seeing conditions. We show that the SFHs of all fields share the same patterns, with consistent variations of the star formation rate as a function of time in all of them. We therefore conclude that no specific event of star formation can be identified with the formation of the LMC bar, which instead likely formed from a redistribution of disk material that occurred when the LMC disk became bar unstable, and shared a common SFH with the inner disk thereafter. The strong similarity between the SFH of the center and edge of the bar rules out significant spatial variations of the SFH across the bar, which are predicted by scenarios of classic bar formation through buckling mechanisms.Comment: MNRAS Letters, accepte

La geografía escolar ante el espejo de su representación social.

En los años sesenta-setenta del siglo XX se produjo un debate relevante sobre la explicación de los hechos y fenómenos sociales. Desde la Geografía y otras ciencias sociales se buscó la explicación del comportamiento humano en relación con el recuerdo del pasado, las relaciones sociales, la valoración espacial o la representación social del sistema escolar. Nuestro objetivo es mostrar los obstáculos que aparecen en el medio académico como referente para la construcción de un espacio público educativo, donde la Geografía pueda manifestar sus competencias para facilitar un aprendizaje útil al conocimiento del medio local en su contexto global

The ISW-tSZ cross correlation: ISW extraction out of pure CMB data

If Dark Energy introduces an acceleration in the universal expansion then large scale gravitational potential wells should be shrinking, causing a blueshift in the CMB photons that cross such structures (Integrated Sachs-Wolfe effect, [ISW]). Galaxy clusters are known to probe those potential wells. In these objects, CMB photons also experience inverse Compton scattering off the hot electrons of the intra-cluster medium, and this results in a distortion with a characteristic spectral signature of the CMB spectrum (the so-called thermal Sunyaev-Zel'dovich effect, [tSZ]). Since both the ISW and the tSZ effects take place in the same potential wells, they must be spatially correlated. We present how this cross ISW-tSZ signal can be detected in a CMB-data contained way by using the frequency dependence of the tSZ effect in multi frequency CMB experiments like {\it Planck}, {\em without} requiring the use of external large scale structure tracers data. We find that by masking low redshift clusters, the shot noise level decreases significantly, boosting the signal to noise ratio of the ISW--tSZ cross correlation. We also find that galactic and extragalactic dust residuals must be kept at or below the level of ~0.04 muK^2 at l=10, a limit that is a factor of a few below {\it Planck}'s expectations for foreground subtraction. If this is achieved, CMB observations of the ISW-tSZ cross correlation should also provide an independent probe for the existence of Dark Energy and the amplitude of density perturbations.Comment: submitted to MNRA

PERSPECTIVAS DE LOS GRADUADOS UNIVERSITARIOS NO TRADICIONALES SOBRE LAS PRÁCTICAS: COMPETENCIAS, EMPLEABILIDAD Y TRANSICIÓN AL MERCADO LABORAL EN ESPAÑA

Employability has become a principal aim of universities in Europe and beyond. In this context, internships are a central strategy for the promotion of employability. This qualitative study, conducted in Spain and based on biographical-narrative interviews, focuses on the voices and experiences of 25 non-traditional university graduates, all from the field of social sciences, on employability, internships, and skills. The data collected are analysed based on four categories: training received at the university; the influence of internships on employability; assessment of the internships; and perspectives on skills in demand and mismatches between graduate profiles and labour market demands. Graduates feel the internships has not helped in the transition to the workplace. Graduates have criticised the lack of connection between university and workplace, the short duration of internships, and the insufficient focus on professional and transversal skills. The results also suggest that universities should develop more initiatives to improve internships, working in coordination with employers and other stakeholders.A empregabilidade tornou-se um objetivo principal das universidades na Europa e fora dela. Neste contexto, os estagios são uma estratégia central para a promoção da empregabilidade. Este estudo qualitativo, realizado na Espanha e baseado em entrevistas biográfico-narrativas, enfoca as vozes e experiências de 25 graduados universitários não tradicionais, todos do campo das ciências sociais, sobre empregabilidade, estágios e habilidades. Os dados coletados são analisados com base em quatro categorias: treinamento recebido na universidade; influência dos estágios na empregabilidade; avaliação dos estágios; e perspectivas sobre habilidades em demanda e desencontros entre perfis de graduados e demandas do mercado de trabalho. Os estagiários sentem que os estágios não têm ajudado na transição para o mercado de trabalho. Os graduados têm criticado a falta de conexão entre universidade e mercado de trabalho, a curta duração dos estágios e o foco insuficiente nas habilidades profissionais e transversais. Os resultados também sugerem que as universidades deveriam desenvolver mais iniciativas para melhorar os estágios, trabalhando em coordenação com empregadores e outras partes interessadas.    La empleabilidad se ha convertido en un objetivo importante de las universidades en Europa y fuera de ella. En este contexto, las prácticas son una estrategia fundamental para la promoción de la empleabilidad. Este estudio cualitativo, realizado en España y basado en entrevistas biográficas, se centra en las voces y experiencias de 25 graduados universitarios no tradicionales, todos ellos del ámbito de las ciencias sociales, sobre la empleabilidad, las prácticas y las competencias. Los datos recogidos se analizan sobre la base de cuatro categorías: la formación recibida en la universidad; la influencia de las prácticas en la empleabilidad; la evaluación de las prácticas; y las perspectivas sobre las competencias demandadas y los desajustes entre los perfiles de los graduados y las demandas del mercado de trabajo. Los graduados consideran que las prácticas no han ayudado a la transición al mercado laboral. Los graduados han criticado la falta de conexión entre la universidad y el mercado laboral, la corta duración de las prácticas y la insuficiente atención a las competencias profesionales y transversales. Los resultados también sugieren que las universidades deberían desarrollar más iniciativas para mejorar las prácticas, trabajando en coordinación con los empleadores y otros grupos interesados. &nbsp

A sweet deal? Sugarcane, water and agricultural transformation in Sub-Saharan Africa

Globally, the area of sugarcane is rising rapidly in response to growing demands for bioethanol and increased sugar demand for human consumption. Despite considerable diversity in production systems and contexts, sugarcane is a particularly “high impact” crop with significant positive and negative environmental and socio-economic impacts. Our analysis is focused on Sub-Saharan Africa (SSA), which is a critical region for continued expansion, due to its high production potential, low cost of production and proximity, and access, to European markets. Drawing on a systematic review of scientific evidence, combined with information from key informants, stakeholders and a research-industry workshop, we critically assess the impacts of sugarcane development on water, soil and air quality, employment, food security and human health. Our analysis shows that sugarcane production is, in general, neither explicitly good nor bad, sustainable nor unsustainable. The impacts of expansion of sugarcane production on the environment and society depend on the global political economy of sugar, local context, quality of scheme, nature of the production system and farm management. Despite threats from climate change and forthcoming changes in the trade relationship with the European Union, agricultural development policies are driving national and international interest and investment in sugarcane in SSA, with expansion likely to play an important role in sustainable development in the region. Our findings will help guide researchers and policy makers with new insights in understanding the situated environmental and social impacts associated with alternative sugar economy models, production technologies and qualities of management

Signals of the cosmological reionization in the radio sky through C and O fine structure lines

We study the excitation of fine structure levels of C I, C II and O I by ultraviolet (UV) photons around strong UV sources which are also ionizing sources of the cosmological reionization at redshift of $\sim 10$. The evolutions of ionized regions around a point source are calculated by solving rate equations for non-equilibrium chemistry. Signals of UV photons through the fine structure lines are considered to be stronger at locations of more abundant chemical species of C I, C II and O I. Such environments would be realized where strong fluxes of non-ionizing UV line photons available for the pumping up of fine structure levels exist, and simultaneously ionizing UV photons are effectively shielded by dense H I regions. Signals from H I regions of moderately large densities induced by redshifted UV photons emitted at the point sources are found to be dominantly large over those of others. We discuss the detectability of the signals, and show that signals from idealized environments will be possibly detected by radio observations with next-generation arrays to come after the Atacama Large Millimeter/submillimeter Array (ALMA).Comment: 23 pages, 21 figures, significant revisions in Secs. 2, 3, and 4, and Appendix, main conclusions unchanged, accepted for publication in Monthly Notices of the Royal Astronomical Societ

Efficient plot-based floristic assessment of tropical forests

The tropical flora remains chronically understudied and the lack of floristic understanding hampers ecological research and its application for large-scale conservation planning. Given scarce resources and the scale of the challenge there is a need to maximize the efficiency of both sampling strategies and sampling units, yet there is little information on the relative efficiency of different approaches to floristic assessment in tropical forests. This paper is the first attempt to address this gap. We repeatedly sampled forests in two regions of Amazonia using the two most widely used plot-based protocols of floristic sampling, and compared their performance in terms of the quantity of floristic knowledge and ecological insight gained scaled to the field effort required. Specifically, the methods are assessed first in terms of the number of person-days required to complete each sample (‘effort’), secondly by the total gain in the quantity of floristic information that each unit of effort provides (‘crude inventory efficiency’), and thirdly in terms of the floristic information gained as a proportion of the target species pool (‘proportional inventory efficiency’). Finally, we compare the methods in terms of their efficiency in identifying different ecological patterns within the data (‘ecological efficiency’) while controlling for effort. There are large and consistent differences in the performance of the two methods. The disparity is maintained even after accounting for regional and site-level variation in forest species richness, tree density and the number of field assistants. We interpret our results in the context of selecting the appropriate method for particular research purposes

Tomography of the Reionization Epoch with Multifrequency CMB Observations

We study the constraints that future multifrequency Cosmic Microwave Background (CMB) experiments will be able to set on the metal enrichment history of the Inter Galactic Medium at the epoch of reionisation. We forecast the signal to noise ratio for the detection of the signal introduced in the CMB by resonant scattering off metals at the end of the Dark Ages. We take into account systematics associated to inter-channel calibration, PSF reconstruction errors and innacurate foreground removal. We develop an algorithm to optimally extract the signal generated by metals during reionisation and to remove accurately the contamination due to the thermal Sunyaev-Zel'dovich effect. Although demanding levels of foreground characterisation and control of systematics are required, they are very distinct from those encountered in HI-21cm studies and CMB polarization, and this fact encourages the study of resonant scattering off metals as an alternative way of conducting tomography of the reionisation epoch. An ACT-like experiment with optimistic assumtions on systematic effects, and looking at clean regions of the sky, can detect changes of 3%-12% (95% c.l.) of the OIII abundance (with respect its solar value) in the redshift range $z\in$ [12,22], for reionization redshift $z_{\rm re}>10$. However, for $z_{\rm re} <10$, it can only set upper limits on NII abundance increments of $\sim$ 60% its solar value in the redshift range $z\in$ [5.5,9], (95% c.l.). These constraints assume that inter-channel calibration is accurate down to one part in $10^{4}$, which constitutes the most critical technical requirement of this method, but still achievable with current technology.Comment: 10 pages, 2 figures, submitted to Astrophysical Journal. Comments are welcom

Cómo evalúa el profesorado de Geografía e Historia de Enseñanza Secundaria

The purpose of this article is to analyse the assessment procedures and instruments used by teachers of Geography and History of Compulsory Secondary School (ESO) in the Region of Murcia (Spain). The data have been extracted implementing a survey technique proceeded by a descriptive analysis. The results show that teachers generally have a traditional conception of assessment, reflected in the fact that they think that assessment should not change when teaching strategies are changed or when they innovate. On the other hand, although they consider that is necessary to employ a variety of instruments to assess well and to prevent school failure, they still use exams as the most objective and essential instrument in the assessment, while they don’t apply continuous assessment, only tests in a continuous way. The implementation of similar research in other areas or in other subjects shows the existence of contrasts in teacher assessment practices.La finalidad de este artículo es analizar los procedimientos e instrumentos de evaluación que emplea el profesorado de Geografía e Historia de Educación Secundaria Obligatoria (ESO) de la Región de Murcia. Los datos han sido extraídos mediante técnica de encuesta, tras un análisis descriptivo. Los resultados indican que en los docentes, en general, predomina una concepción tradicional de la evaluación, traducida en el hecho de que estos piensan que no deben cambiar su evaluación al cambiar su práctica docente o al innovar. Por otro lado, aunque consideran que es necesario emplear gran variedad de instrumentos para evaluar bien y para evitar el fracaso escolar, siguen empleando mayoritariamente el examen como el instrumento más objetivo e imprescindible en la evaluación, tanto que no llega a practicarse la evaluación continua, sino continuos exámenes. La puesta en marcha de investigaciones similares en otros territorios o en otras materias del currículo mostraría la existencia o no de contrastes en las prácticas de evaluación del profesorado

Optimal management of the Jucar River and Turia River basins under uncertain drought conditions

This paper presents a methodology to assess the best behavior achievable for a water resources system, and we apply it to the joint system of the Jucar River and Turia River basins in Spain. The resources of the two rivers are used jointly to meet the different water uses within the region, especially urban demands and environmental requirements. The climate change effects in this area are predicted to be particularly severe in this area with great variability in drought patterns. The results are particularly suitable for evaluating the best performance of the system under uncertain conditions