Galaxy size trends as a consequence of cosmology

We show that recently documented trends in galaxy sizes with mass and redshift can be understood in terms of the influence of underlying cosmic evolution; a holistic view which is complimentary to interpretations involving the accumulation of discreet evolutionary processes acting on individual objects. Using standard cosmology theory, supported with results from the Millennium simulations, we derive expected size trends for collapsed cosmic structures, emphasising the important distinction between these trends and the assembly paths of individual regions. We then argue that the observed variation in the stellar mass content of these structures can be understood to first order in terms of natural limitations of cooling and feedback. But whilst these relative masses vary by orders of magnitude, galaxy and host radii have been found to correlate linearly. We explain how these two aspects will lead to galaxy sizes that closely follow observed trends and their evolution, comparing directly with the COSMOS and SDSS surveys. Thus we conclude that the observed minimum radius for galaxies, the evolving trend in size as a function of mass for intermediate systems, and the observed increase in the sizes of massive galaxies, may all be considered an emergent consequence of the cosmic expansion.Comment: 14 pages, 13 figures. Accepted by MNRA

¿Sufren las mujeres inmigrantes una doble penalización salarial? Evidencia para España

El artículo examina los salarios relativos de las mujeres inmigrantes en España mediante la Encuesta de Estructura Salarial a través de una doble comparación con los hombres inmigrantes y las mujeres nativas. El análisis empírico muestra que las mujeres inmigrantes presentan desventajas salariales significativas frente a ambos colectivos. Los resultados de los ejercicios de descomposición de estas diferencias salariales permiten constatar que mientras que una parte importante de la desventaja salarial frente a los varones inmigrantes no resulta explicada por las diferencias en dotaciones de características productivas, por el contrario, la brecha salarial frente a las mujeres nativas es explicada en buena medida por este elemento. En consecuencia, la evidencia obtenida para España no concuerda plenamente con la hipótesis de la existencia de una doble penalización salarial para las mujeres inmigrantes.This study examines immigrant women relative wages in Spain as compared to those earned by immigrant men and native women on the basis of microdata from the Encuesta de Estructura Salarial. The results show that foreign-born women wages are significantly lower than those corresponding to both groups. It is also found that the wage gap compared to native women is explained largely by native women’s better endowments of productive characteristics whereas, on the contrary, a significant part of the wage disadvantage relative to male immigrants is not explained by this element. As a consequence, empirical evidence for the case of Spain does not seem to fully support the hypothesis of a double wage penalty for immigrant women.Este trabajo se ha beneficiado de la financiación del proyecto de investigación CSO2011-29943-C03-02 del Ministerio de Educación, Cultura y Deporte

La Gran Recesión y el diferencial salarial por género en España

El artículo examina la evolución de las diferencias salariales entre hombres y mujeres en España entre los años 2002 y 2010. La evidencia obtenida sugiere que el notable empeoramiento de la coyuntura económica tras el inicio de la Gran Recesión ha tenido dos impactos reseñables sobre el diferencial salarial por razón de género. El primero es que se ha revertido la tendencia hacia la reducción de la brecha salarial por género que se venía produciendo en la economía española con anterioridad, durante la expansión económica. El segundo es que se ha generado un perfil creciente de la brecha salarial a lo largo de la distribución de salarios coincidente con el fenómeno de techo de cristal observado para otros países, pero no en períodos previos para España.This article examines the evolution of the gender wage gap in Spain between 2002 and 2010. The evidence suggests that the significant worsening of the economic situation after the onset of the Great Recession has had two significant impacts on the gap. The first is that it has reversed the trend towards the reduction of the gender pay gap in the Spanish economy during the previous economic expansion. The second is that it has generated a growing profile of the wage gap across the wage distribution which is consistent with the glass ceiling phenomenon observed for other advanced countries, but not in previous periods for Spain.Este trabajo se ha beneficiado de la financiación del proyecto de investigación CSO2011-29943-C03-02 del Ministerio de Educación, Cultura y Deporte

Soft clustering analysis of galaxy morphologies: A worked example with SDSS

Context: The huge and still rapidly growing amount of galaxies in modern sky surveys raises the need of an automated and objective classification method. Unsupervised learning algorithms are of particular interest, since they discover classes automatically. Aims: We briefly discuss the pitfalls of oversimplified classification methods and outline an alternative approach called "clustering analysis". Methods: We categorise different classification methods according to their capabilities. Based on this categorisation, we present a probabilistic classification algorithm that automatically detects the optimal classes preferred by the data. We explore the reliability of this algorithm in systematic tests. Using a small sample of bright galaxies from the SDSS, we demonstrate the performance of this algorithm in practice. We are able to disentangle the problems of classification and parametrisation of galaxy morphologies in this case. Results: We give physical arguments that a probabilistic classification scheme is necessary. The algorithm we present produces reasonable morphological classes and object-to-class assignments without any prior assumptions. Conclusions: There are sophisticated automated classification algorithms that meet all necessary requirements, but a lot of work is still needed on the interpretation of the results.Comment: 18 pages, 19 figures, 2 tables, submitted to A

A robust morphological classification of high-redshift galaxies using support vector machines on seeing limited images. II. Quantifying morphological k-correction in the COSMOS field at 1<z<2: Ks band vs. I band

We quantify the effects of \emph{morphological k-correction} at $1<z<2$ by comparing morphologies measured in the K and I-bands in the COSMOS area. Ks-band data have indeed the advantage of probing old stellar populations for $z<2$, enabling a determination of galaxy morphological types unaffected by recent star formation. In paper I we presented a new non-parametric method to quantify morphologies of galaxies on seeing limited images based on support vector machines. Here we use this method to classify $\sim$$50 000$ $Ks$ selected galaxies in the COSMOS area observed with WIRCam at CFHT. The obtained classification is used to investigate the redshift distributions and number counts per morphological type up to $z\sim2$ and to compare to the results obtained with HST/ACS in the I-band on the same objects from other works. We associate to every galaxy with $Ks<21.5$ and $z<2$ a probability between 0 and 1 of being late-type or early-type. The classification is found to be reliable up to $z\sim2$. The mean probability is $p\sim0.8$. It decreases with redshift and with size, especially for the early-type population but remains above $p\sim0.7$. The classification is globally in good agreement with the one obtained using HST/ACS for $z<1$. Above $z\sim1$, the I-band classification tends to find less early-type galaxies than the Ks-band one by a factor $\sim$1.5 which might be a consequence of morphological k-correction effects. We argue therefore that studies based on I-band HST/ACS classifications at $z>1$ could be underestimating the elliptical population. [abridged]Comment: accepted for publication in A&A, updated with referee comments, 12 pages, 10 figure

¿Es rentable para el sector público invertir en educación?

The present paper analyzes one of the advantages that a country can derive from people with higher educational levels, i.e. higher tax revenues resulting from the higher earnings from higher school attainment.More specifically, we test whether the marginal revenue obtained by the public sector from taxpayers holding an additional educational level is higher than the marginal public expenditure on them. To accomplish this aim, we extend Psacharopoulos (1981) analysis and calculate internal rates of return for public expenditure in schooling. Our results suggest that taxpayers with an additional educational level, including those attaining post-compulsory educational levels, are profitable for the public sector.Education expenditure, tax burden, internal rate of return.

Proximity effect-assisted absorption of spin currents in superconductors

The injection of pure spin current into superconductors by the dynamics of a ferromagnetic contact is studied theoretically. Taking into account suppression of the order parameter at the interfaces (inverse proximity effect) and the energy-dependence of spin-flip scattering, we determine the temperature-dependent ferromagnetic resonance linewidth broadening. Our results agree with recent experiments in Nb|permalloy bilayers [C. Bell et al., arXiv:cond-mat/0702461].Comment: 4 page

Revisiting interregional wage differentials: New evidence from Spain with matched employer‐employee data

This article examines wage differences across Spain's NUTS‐2 regions along the entire wage distribution based on matched employer‐employee microdata from 2006 to 2014. Unlike previous related studies, we properly control for differences in regional purchasing power parities, which are very large in practice. Although part of the raw regional wage differences observed is explained by differences between regions in productive structures, and, to a much lesser extent, in labor forces, noteworthy, very similar throughout the wage distribution regional differences net of composition effects arise even after controlling for a broad set of individual and firm characteristics.This work was supported by the Spanish Ministry of Science, Innovation and Universities (Agencia Estatal de Investigación), the European Union (ERDF), and the Junta de Extremadura (grant numbers CSO2017‐86474‐R, ECO2014‐53702‐P, and ECO2016‐75805‐R, National Plan for Research, Development and Innovation, Spain, and GR18106)

FEM based mathematical modelling of thrust force during drilling of Al7075-T6

Like most machining processes, drilling is affected by many parameters such as the tool diameter, the cutting speed and feed. The current research investigates the possibility of developing a finite element modelling based prediction model for the generated thrust force during drilling of Al7075-T6 with solid carbide tools. A total of 27 drilling experiments were carried out in order to examine the interaction between three key parameters and their effect on thrust force. In addition, simulations of the experiments were realized with the use of DEFORM3D((TM))software in order to obtain the necessary numerical data. Finally, a comparison was made between the experimental and the numerical results to verify that reliable modelling is feasible. The mathematical model was acquired with the use of response surface methodology and the verification of the adequacy of the model was performed through an analysis of variance. The majority of the simulations yielded results in agreement with the experimental results at around 95% and the derived model offered an accuracy of 5.9%

CAD-Based Automated Design of FEA-Ready Cutting Tools

The resources of modern Finite Element Analysis (FEA) software provide engineers with powerful mechanisms that can be used to investigate numerous machining processes with satisfying results. Nevertheless, the success of a simulation, especially in three dimensions, relies heavily on the accuracy of the cutting tool models that are implemented in the analyses. With this in mind, the present paper presents an application developed via Computer-Aided Design (CAD) programming that enables the automated design of accurate cutting tool models that can be used in 3D turning simulations. The presented application was developed with the aid of the programming resources of a commercially available CAD system. Moreover, the parametric design methodology was employed in order to design the tools according to the appropriate standards. Concluding, a sample tool model was tested by performing a number of machining simulations based on typical cutting parameters. The yielded results were then compared to experimental values of the generated machining force components for validation. The findings of the study prove the functionality of the tool models since a high level of agreement occurred between the acquired numerical results and the experimental ones