4,521 research outputs found
Do wage subsidies affect the subsequent employment stability of permanent workers?: the case of Spain
This article studies how job creation subsidies designed for several Spanish regional governments to foster the creation of new permanent contracts during the period 1997-2004 might affect the subsequent employment stability of the eligible workers. We use a triple difference approach that focuses on regional and temporal variability in individual eligibility conditions of these subsidies to obtain the causal effect of the policy. Our data comes from the Muestra Continua de Vidas Laborales (MCVL) and from a database that contains information on the policy analyzed. Our main result is that workers who are eligible for these subsidies face a higher probability of exiting from their current permanent contract than those who do not. These effects vary by age and gender, as well as by contract duration and contract type. This result is particularly relevant for male workers whose contracts also benefited with nationally subsidized payroll deductions and for women with such deductions but only during their first year of employment. During that initial first-year period, the exit rate among eligible workers in our sample increased by 9%, 21% and 16% for younger, middle-aged and older female workers, respectively, and by about 13% and 25% for younger and older male workers, respectively.labour market rotation, permanent contracts, wage subsidies, triple difference, causal inference, average treatment effects, duration model.
The use of permanent and temporary jobs across Spanish regions: Do unit labour cost differentials offer an explanation?
We study the use of permanent and temporary contracts across Spanish regions during the period 1995-2001. First we show that there are significant differences among the regional rates of permanent employment and that these differences tend to persist over time. To understand the underlying factors behind these observed differences we estimate a binary choice model for the individual probability of having a permanent contract, taking advantage of the panel data dimension of the Spanish Labour Force Survey. Our main results are that unit labour cost differentials, and thus labour productivity and total labour cost differentials, partially explain the divergence of regional permanent employment rates. Moreover, compared to the influence of regional fixed effects and other possible explanations such as sector specialisation or the presence of small firms in the region, unit labour costs explain more than two thirds of the observed variance in the permanent employment rate across Spanish regions, once all the relevant heterogeneity is taken into account.Temporary Employment, Unit Labour Costs, Random Effects, Spanish Regions.
New capabilities for Monte Carlo simulation of deuteron transport and secondary products generation
Several important research programs are dedicated to the development of facilities based on deuteron accelerators. In designing these facilities, the definition of a validated computational approach able to simulate deuteron transport and evaluate deuteron interactions and production of secondary particles with acceptable precision is a very important issue. Current Monte Carlo codes, such as MCNPX or PHITS, when applied for deuteron transport calculations use built-in semi-analytical models to describe deuteron interactions. These models are found unreliable in predicting neutron and photon generated by low energy deuterons, typically present in those facilities.
We present a new computational tool, resulting from an extension of the MCNPX code, which improve significantly the treatment of problems where any secondary product (neutrons, photons, tritons, etc.) generated by low energy deuterons reactions could play a major role. Firstly, it handles deuteron evaluated data libraries, which allow describing better low deuteron energy interactions. Secondly, it includes a reduction variance technique for production of secondary particles by charged particle-induced nuclear interactions, which allow reducing drastically the computing time needed in transport and nuclear response calculations. Verification of the computational tool is successfully achieved. This tool can be very helpful in addressing design issues such as selection of the dedicated neutron production target and accelerator radioprotection analysis. It can be also helpful to test the deuteron cross-sections under development in the frame of different international nuclear data program
La gestiĂłn del tiempo por parte de los profesores principiantes
En el curso 2010-2011 se ha constituido en el Departamento de Derecho Financiero y Tributario de la Facultad de Derecho de la Universidad de Sevilla un equipo docente, formado por un profesor principiante y un profesor mentor con amplia experiencia docente para participar en el Programa de FormaciĂłn de Profesores Noveles de la Universidad de Sevilla. La finalidad del proyecto era facilitar la introducciĂłn en la funciĂłn docente del profesor novel y, especĂficamente, dotarle de los instrumentos adecuados para una adecuada gestiĂłn del tiempo, herramientas para una comunicaciĂłn eficaz y pautas sobre el uso correcto de los medios de apoyo a la exposiciĂłn en clase, particularmente medios TIC.A teaching group was created in the Department of Tax Law (Faculty of Law, University of Seville) for the 2010-2011 academic year in order to participate in the teacher training program at the University of Seville. This group consisted of a novice teacher and a mentor teacher with extensive teaching experience. The objective of the project was to ease the introduction of the novice teachers into their educational role, and specifically to provide them with the right tools both for planning and scheduling, and for effective communication, and with guidelines on the proper use of ICT and other resources as an aid to class presentation
Matrix Product States: Symmetries and Two-Body Hamiltonians
We characterize the conditions under which a translationally invariant matrix
product state (MPS) is invariant under local transformations. This allows us to
relate the symmetry group of a given state to the symmetry group of a simple
tensor. We exploit this result in order to prove and extend a version of the
Lieb-Schultz-Mattis theorem, one of the basic results in many-body physics, in
the context of MPS. We illustrate the results with an exhaustive search of
SU(2)--invariant two-body Hamiltonians which have such MPS as exact ground
states or excitations.Comment: PDFLatex, 12 pages and 6 figure
A scenario of planet erosion by coronal radiation
Context: According to theory, high-energy emission from the coronae of cool
stars can severely erode the atmospheres of orbiting planets. No observational
tests of the long term effects of erosion have yet been made. Aims: To analyze
the current distribution of planetary mass with X-ray irradiation of the
atmospheres in order to make an observational assessment of the effects of
erosion by coronal radiation. Methods: We study a large sample of
planet-hosting stars with XMM-Newton, Chandra and ROSAT; make a careful
identification of X-ray counterparts; and fit their spectra to make accurately
measurements of the stellar X-ray flux. Results: The distribution of the
planetary masses with X-ray flux suggests that erosion has taken place: most
surviving massive planets, (M_p sin i >1.5 M_J), have been exposed to lower
accumulated irradiation. Heavy erosion during the initial stages of stellar
evolution is followed by a phase of much weaker erosion. A line dividing these
two phases could be present, showing a strong dependence on planet mass.
Although a larger sample will be required to establish a well-defined erosion
line, the distribution found is very suggestive. Conclusions: The distribution
of planetary mass with X-ray flux is consistent with a scenario in which planet
atmospheres have suffered the effects of erosion by coronal X-ray and EUV
emission. The erosion line is an observational constraint to models of
atmospheric erosion.Comment: A&A 511, L8 (2010). 4 pages, 3 figures, 1 online table (included).
Language edited; corrected a wrong unit conversion (g/s -> M_J/Gyr);
corrected values in column 12 of Table 1 (slightly underestimated in first
version), and Figure 2 updated accordingl
Molecular Dynamics Simulations for Genetic Interpretation in Protein Coding Regions: Where we Are, Where to Go and When
The increasing ease with which massive genetic information can be obtained from patients or healthy individuals has stimulated the development of interpretive bioinformatics tools as aids in clinical practice. Most such tools analyze evolutionary information and simple physicalâchemical properties to predict whether replacement of one amino acid residue with another will be tolerated or cause disease. Those approaches achieve up to 80â85% accuracy as binary classifiers (neutral/pathogenic). As such accuracy is insufficient for medical decision to be based on, and it does not appear to be increasing, more precise methods, such as full-atom molecular dynamics (MD) simulations in explicit solvent, are also discussed. Then, to describe the goal of interpreting human genetic variations at large scale through MD simulations, we restrictively refer to all possible protein variants carrying single-amino-acid substitutions arising from single-nucleotide variations as the human variome. We calculate its size and develop a simple model that allows calculating the simulation time needed to have a 0.99 probability of observing unfolding events of any unstable variant. The knowledge of that time enables performing a binary classification of the variants (stable-potentially neutral/unstable-pathogenic). Our model indicates that the human variome cannot be simulated with present computing capabilities. However, if they continue to increase as per Mooreâs law, it could be simulated (at 65°C) spending only 3 years in the task if we started in 2031. The simulation of individual protein variomes is achievable in short times starting at present. International coordination seems appropriate to embark upon massive MD simulations of protein variants
Control architecture of the ATLAS 2020 lower-limb active orthosis
This paper outlines the
control details implemented in the wearable gait exoskeleton ATLAS 2020 for
improving the therapy of SMA children. This paper discusses the control challenges
of a gait-training wearable exoskeleton for SMA children. Such device would
also increase these children's quality of life, achieving a reduction of disability
and increased functional independence.Peer reviewe
Massive Parallel Current Power Amplifier Concept for Power Hardware in the Loop Applications
The development of the smartgrid increases the complexity of the current electric grid. To verify and validate the operation of the systems involved in it, Power Hardware-In-theLoop (PHIL) technique allows to test the complete system in an exhaustive way. But the reduced bandwidth of the overall test system can cause inaccuracies and instabilities, which can be harmful for the Hardware Under Test (HUT) or the people who are performing the test. To increase PHIL performance and tackle these problems, this paper proposes a new concept of high bandwidth current amplifier. It is based on a topology of massive parallel interleaved buck-boost converter, which distribute in an equal manner the total current in all the branches. This current reduction allows to use transistors with better switching behaviour, which increase the bandwidth of the converter. Furthermore, a Discontinuous Conduction Mode (DCM) is used, obtaining the nominal output current in only one switching cycle. Description of the concept and the design parameters are provided. Finally, the behaviour of the proposed Power Amplifier (PA) at high frequency setpoint currents is shown in a Matlab/Simulink simulation. © 2022, European Association for the Development of Renewable Energy, Environment and Power Quality (EA4EPQ). All rights reserved
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