An Approach to Publish Spatial Data on the Web: The GeoLinked Data Case

In this paper we report on an ongoing process aimed at publishing hydrographical data on the Web with a Spanish GeoLinked Data Use Case. Moreover, we discuss the process we followed, and propose methodological guidelines for all the activities involved within the process

On the Environmental Dependence of Cluster Galaxy Assembly Timescale

We present estimates of CN and Mg overabundances with respect to Fe for early-type galaxies in 8 clusters over a range of richness and morphology. Spectra were taken from the Sloan Digital Sky Survey (SDSS) DR1, and from WHT and CAHA observations. Abundances were derived from absorption lines and single burst population models, by comparing galaxy spectra with appropriately broadened synthetic model spectra. We detect correlations between [Mg/CN] and [CN/Fe] and cluster X-ray luminosity. No correlation is observed for [Mg/Fe]. We also see a clear trend with the richness and morphology of the clusters. This is interpreted given varying formation timescales for CN, Mg and Fe, and a varying star formation history in early-type galaxies as a function of their environment: intermediate-mass early-type galaxies in more massive clusters are assembled on shorter timescales than in less massive clusters, with an upper limit of ~1 Gyr.Comment: Accepted for publication in ApJ Letter

Construcción de ontologías a partir de tesauros

Tradicionalmente, los tesauros han sido una de las formas más extendidas para la organización y formalización del conocimiento. Estos, a través de su vocabulario controlado y relaciones, resultan destacados instrumentos para la organización y gestión del conocimiento de un área específica. La importancia de estas formas de organización originó tres estándares para llevar a cabo un proceso de construcción normalizado. El surgimiento de la Web Semántica permite que los datos sean compartidos y reutilizados a través de diferentes aplicaciones y comunidades. Este hecho conlleva un replanteamiento de las formas de organización del conocimiento y, por tanto, un cambio de estrategia. Estos cambios están vinculados a la necesidad de especificar de manera formal y explícita la semántica asociada a la información de una manera más eficiente que la realizada hasta el momento por los tesauros. Ante esta situación, el uso y desarrollo de ontologías se manifiesta como la mejor forma de especificar la semántica según lo requiere la Web Semántica. Esto está motivando que el proceso de reingeniería y/o la migración de los tesauros tradicionales a ontologías se esté convirtiendo en una tendencia actual

GeoLinked Data. An application case / Un caso de aplicación

In this paper we present the process that has been followed for the development of an application that makes use of several heterogeneous Spanish public datasets that are related to three themes of INSPIRE Directive, specifically Administrative Units, Hydrography, and Statistical Units. Our application aims at analysing existing relations between the Spanish coastal area and different statistical variables such as population, unemployment, dwelling, industry, and building trade. Besides providing ethodological guidelines for the generation, publishing and exploitation of Linked Data from such datasets, we provide an important innovation with respect to other similar processes followed in other initiatives by dealing with the geometrical information of features

Threading Through Macrocycles Enhances the Performance of Carbon Nanotubes as Polymer Fillers

In this work we study the reinforcement of polymers by mechanically interlocked derivatives of single-walled carbon nanotubes (SWNTs). We compare the mechanical properties of fibers made of polymers and of composites with pristine single-walled carbon nanotubes (SWNTs), mechanically interlocked derivatives of SWNTs (MINTs) and the corresponding supramolecular models. Improvements of both Young's modulus and tensile strength of up to 200 % were observed for the polystyrene-MINTs samples with an optimized loading of just 0.01 wt.%, while the supramolecular models with identical chemical composition and loading showed negligible or even detrimental influence. This behavior is found for three different types of SWNTs and two types of macrocycles. Molecular dynamics simulations show that the polymer adopts an elongated conformation parallel to the SWNT when interacting with MINT fillers, irrespective of the macrocycle chemical nature, whereas a more globular structure is taken upon facing with either pristine SWNTs or supramolecular models. The MINT composite architecture thus leads to a more efficient exploitation of the axial properties of the SWNTs and of the polymer chain at the interface, in agreement with experimental results. Our findings demonstrate that the mechanical bond imparts distinctive advantageous properties to SWNT derivatives as polymer fillers.Comment: 39 pages, 19 figure

A search for dark matter among Fermi-LAT unidentified sources with systematic features in Machine Learning

Around one third of the point-like sources in the Fermi-LAT catalogs remain as unidentified sources (unIDs) today. Indeed, these unIDs lack a clear, univocal association with a known astrophysical source. If dark matter (DM) is composed of weakly interacting massive particles (WIMPs), there is the exciting possibility that some of these unIDs may actually be DM sources, emitting gamma rays from WIMPs annihilation. We propose a new approach to solve the standard, Machine Learning (ML) binary classification problem of disentangling prospective DM sources (simulated data) from astrophysical sources (observed data) among the unIDs of the 4FGL Fermi-LAT catalogue. Concretely, we artificially build two systematic features for the DM data which are originally inherent to observed data: the detection significance and the uncertainty on the spectral curvature. We do it by sampling from the observed population of unIDs, assuming that the DM distributions would, if any, follow the latter. We consider different ML models: Logistic Regression, Neural Network (NN), Naive Bayes and Gaussian Process, out of which the best, in terms of classification accuracy, is the NN, achieving around 93% performance. Applying the NN to the unIDs sample, we find that the degeneracy between some astrophysical and DM sources can be partially solved within this methodology. Nonetheless, we conclude that there are no DM source candidates among the pool of 4FGL Fermi-LAT unIDs.Comment: 13 pages, 14 figures, ready for submission to MNRA

Sex-moderated socio-labor aspects as mediators of a cognitive stimulation program in older adults: randomized clinical trial

Cognitive stimulation is essential for successful aging. The influence of sex and socio-occupational elements on this area remains unknown. This study aimed to analyze the possible mediation of those elements in the effectiveness of a cognitive stimulation program in primary care. A randomized clinical trial was conducted with 232 adults aged 65 years or older without cognitive impairment. The intervention produced significant cognitive improvements. Women improved independently of social and occupational factors, while men’s improvement occurred at a low role level (zero to one), a medium level of interests (two to three), with a medium level of mental occupation (neither high nor low), and with marked personal values. The mediating variables were the intervention group in both sexes and, also in men, a low and medium role level. Therefore, the intervention and roles appear as mediating variables moderated by sex. In conclusion, cognitive stimulation programs should be adapted

The history of star formation and mass assembly in early-type galaxies

We define a volume limited sample of over 14,000 early-type galaxies (ETGs) selected from data release six of the Sloan Digital Sky Survey. The density of environment of each galaxy is robustly measured. By comparing narrow band spectral line indices with recent models of simple stellar populations (SSPs) we investigate trends in the star formation history as a function of galaxy mass (velocity dispersion), density of environment and galactic radius. We find that age, metallicity and alpha-enhancement all increase with galaxy mass and that field ETGs are younger than their cluster counterparts by ~2 Gyr. We find negative radial metallicity gradients for all masses and environments, and positive radial age gradients for ETGs with velocity dispersion over 180 km/s. Our results are qualitatively consistent with a relatively simple picture for ETG evolution in which the low-mass halos accreted by a proto-ETG contained not only gas but also a stellar population. This fossil population is preferentially found at large radii in massive ETGs because the stellar accretions were dissipationless. We estimate that the typical, massive ETG should have been assembled at z < 3.5. The process is similar in the cluster and the field but occurred earlier in dense environments.Comment: 5 pages, 2 figures. Submitted to MNRA

Geographical Linked Data: a Spanish Use Case

We present the process that has been followed for the development of an application that makes use of several heterogeneous Spanish public datasets that are related to administrative, hydrographic, and statistical domains. Our application aims at analysing existing relations between the Spanish coastal area and dierent statistical variables such as unemployment, population, dwelling, industry, and building trade. Moreover, we provide an important innovation with respect to other similar processes followed in other initiatives by dealing with the geometrical information of features