1,218 research outputs found
The wage gap between immigrant and native workers in Spain: an analysis using matched employer-employee data
The fact that Spain has witnessed a sharp increase in the number of immigrants over the past decade has generated considerable interest, particularly as regards wages earned by immigrants in host industries. We analyze whether controlling for both observable and unobservable characteristics of employers —in addition to individual variables and the economic context— makes any difference as regards the debate regarding the existence of wage differences between immigrant and native workers in Spain. As we show, doing this considerably reduces (or even eliminates) the inequalities found in previous research, thereby questioning the results attained by previous studies on this issue.Immigration, salaries, assimilation.
On the relation between the IR continuum and the active galactic nucleus in Seyfert galaxies
A sample of the brightest known Seyfert galaxies from the CfA sample is
analyzed on the basis of ISO photometric and spectroscopic data.
Regardless of the Seyfert type, the mid-IR continuum emission from these
galaxies is found to be correlated with the coronal line emission arising in
the nuclear active region. Conversely, the correlation degrades progressively
when moving from the mid- to the far-IR emission, where it ends to vanish. It
is concluded that the mid-IR emission is largely dominated by dust heated by
processes associated with the active nucleus whereas the far-IR is a different
component most probably unrelated with the active region. We suggest that the
far-IR component is due to dust heated by the stellar population in the disks
of these galaxies.Comment: 6 pages, 3 figures To be published in Astronomy and Astrophysic
Wear Fast, Die Young: More Worn Teeth and Shorter Lives in Iberian Compared to Scottish Red Deer
Teeth in Cervidae are permanent structures that are not replaceable or repairable; consequently their rate of wear, due to the grinding effect of food and dental attrition, affects their duration and can determine an animal's lifespan. Tooth wear is also a useful indicator of accumulative life energy investment in intake and mastication and their interactions with diet. Little is known regarding how natural and sexual selection operate on dental structures within a species in contrasting environments and how these relate to life history traits to explain differences in population rates of tooth wear and longevity. We hypothesised that populations under harsh environmental conditions should be selected for more hypsodont teeth while sexual selection may maintain similar sex differences within different populations. We investigated the patterns of tooth wear in males and females of Iberian red deer (Cervus elaphus hispanicus) in Southern Spain and Scottish red deer (C. e. scoticus) across Scotland, that occur in very different environments, using 10343 samples from legal hunting activities. We found higher rates of both incisor and molar wear in the Spanish compared to Scottish populations. However, Scottish red deer had larger incisors at emergence than Iberian red deer, whilst molars emerged at a similar size in both populations and sexes. Iberian and Scottish males had earlier tooth depletion than females, in support of a similar sexual selection process in both populations. However, whilst average lifespan for Iberian males was 4 years shorter than that for Iberian females and Scottish males, Scottish males only showed a reduction of 1 year in average lifespan with respect to Scottish females. More worn molars were associated with larger mandibles in both populations, suggesting that higher intake and/or greater investment in food comminution may have favoured increased body growth, before later loss of tooth efficiency due to severe wear. These results illustrate how independent selection in both subspecies, that diverged 11,700 years BP, has resulted in the evolution of different longevity, although sexual selection has maintained a similar pattern of relative sex differences in tooth depletion. This study opens interesting questions on optimal allocation in life history trade-offs and the independent evolution of allopatric populations.The European Union Lifelong Learning programme (Leonardo da Vinci) supported the post-graduate students that collaborated in this study. The Scottish Government through the Rural and Environment Science and Analytical Services Division (RESAS), Deer Commission Scotland and Scottish Natural Heritage (project RP64) and Spanish Ministry of Science (projects CGL2007-63594 and CGL2010-17163) funded this study. During the writing up of this study FJPB was granted with a visiting professor fellowship by the University of Cordoba (Spain)
On the relation between the coronal line emission and the IR/X-ray emission in Seyfert galaxies
The relation between the X-ray, the coronal line and the infrared (IR)
emissions in a sample of the brightest known Seyfert galaxies is analysed. A
close relationship between the absorption-corrected soft X-ray emission and
both the mid-IR and the coronal line emission is found for the Seyfert type 2
objects in the sample. The coronal line and the X-ray emissions are both main
tracers of the central activity, hence their relationship with the mid-IR
emission points to nuclear energetic process as the main responsibles of the
heating of the circumnuclear dust. On the other hand, the above relations do
not seem to hold for the Seyfert type 1 discussed in the sample, at least when
the comparisons are done in a flux diagram. This is partially because of the
reduced number of objects of this type analysed in this work and the fact that
the measured soft X-ray emission in Seyfert 1s is systematically larger, by at
least an order of magnitude, than that in the Seyfert 2 counterparts. Finally,
the hard X-ray emission in the studied sample appears unrelated to either the
mid-IR or the coronal line emission.Comment: 14 pages, 3 figures To be published in MNRAS (accepted
IBSE: An OWL Interoperability Evaluation Infrastructure
The technology that supports the Semantic Web presents a great diversity and, whereas all the tools use different types of ontologies, not all of them share a common knowledge representation model, which may pose problems when they try to interoperate. The Knowledge Web European Network of Excellence is organizing a benchmarking of interoperability of ontology tools using OWL as interchange language with the goal of assessing and improving tool interoperability. This paper presents the development of IBSE, an evaluation infrastructure that allows executing automatically the benchmarking experiments and provides an easy way of analysing the results. Thus,including new tools into the evaluation infrastructure will be simple and straightforward
A Modal-Based Partition of Unity Finite Element Method for Elastic Wave Propagation Problems in Layered Media
Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] The time-harmonic propagation of elastic waves in layered media is simulated numerically by means of a modal-based Partition of Unity Finite Element Method (PUFEM). Instead of using the standard plane waves or the Bessel solutions of the Helmholtz equation to design the discretization basis, the proposed modal-based PUFEM explicitly uses the tensor-product expressions of the eigenmodes (the so-called Love and interior modes) of a spectral elastic transverse problem, which fulfil the coupling conditions among layers. This modal-based PUFEM approach does not introduce quadrature errors since the coefficients of the discrete matrices are computed in closed-form. A preliminary analysis of the high condition number suffered by the proposed method is also analyzed in terms of the mesh size and the number of eigenmodes involved in the discretization. The numerical methodology is validated through a number of test scenarios, where the reliability of the proposed PUFEM method is discussed by considering different modal basis and source terms. Finally, some indicators are introduced to select a convenient discrete PUFEM basis taking into account the observability of cracks located on a coupling boundary between two adjacent layers.This work has been supported by Xunta de Galicia project “Numerical simulation of high-frequency hydro-acoustic problems in coastal environments - SIMNUMAR” (EM2013/052), co-funded with European Regional Development Funds (ERDF). Moreover, the second and fifth authors have been supported by MICINN projects MTM2014-52876-R, MTM2017-82724-R, PID2019-108584RB-I00, and also by ED431C 2018/33 - M2NICA (Xunta de Galicia & ERDF) and ED431G 2019/01 - CITIC (Xunta de Galicia & ERDF). Additionally, the third author has been supported by Junta de Castilla y León under projects VA024P17 and VA105G18, co-financed by ERDF funds. This work has been funded for open access charge by Universidade da Coruña/CISUGXunta de Galicia; EM2013/052Xunta de Galicia; ED431C 2018/33Xunta de Galicia; ED431G 2019/01Junta de Castilla y León; VA024P17Junta de Castilla y León; VA105G1
Transient interference of transmission and incidence
Due to a transient quantum interference during a wavepacket collision with a
potential barrier, a particular momentum, that depends on the potential
parameters but is close to the initial average momentum, becomes suppressed.
The hole left pushes the momentum distribution outwards leading to a
significant constructive enhancement of lower and higher momenta. This is
explained in the momentum complex-plane language in terms of a saddle point and
two contiguous ``structural'' poles, which are not associated with resonances
but with incident and transmitted components of the wavefunction.Comment: 4 pages of text, 6 postscript figures, revte
Evolution induced by dry minor mergers onto fast-rotator S0 galaxies
We analysed collisionless N-body simulations of intermediate and minor dry
mergers onto S0s to test whether these mergers can generate S0 galaxies with
kinematics intermediate between fast and slow rotators. We find that minor
mergers induce a lower decrease of the global rotational support than
encounters of lower mass ratios, which results in S0s with properties
intermediate between fast and slow rotators. The resulting remnants are
intrinsically more triaxial, less flattened, and span the whole range of
apparent ellipticities up to . They do not show
lower apparent ellipticities in random projections than initially; on the
contrary, the formation of oval distortions and the disc thickening increase
the percentage of projections at . In the
experiments with S0b progenitor galaxies, minor mergers tend to spin up the
bulge and to decrease slightly its intrinsic ellipticity, whereas in the cases
of primary S0c galaxies they keep the rotational support of the bulge nearly
constant and decrease significantly its intrinsic ellipticity. The remnant
bulges remain nearly spherical (), but exhibit a wide range
of triaxialities (). In the plane of global anisotropy of
velocities () vs. intrinsic ellipticity (),
some of our models extend the linear trend found in previous major merger
simulations towards higher values, while others
depart from it. This is consistent with the wide dispersion exhibited by real
S0s in this diagram compared with ellipticals, which follow the linear trend
drawn by major merger simulations. The different trends exhibited by
ellipticals and S0 galaxies in the - diagram may
be pointing to the different role played by major mergers in the build-up of
each morphological type.Comment: Corrected typos. 20 pages, 14 figures. Accepted for publishing in A&
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