5,294 research outputs found
SPH simulations of the chemical evolution of bulges
We have implemented a chemical evolution model on the parallel AP3M+SPH DEVA
code which we use to perform high resolution simulations of spiral galaxy
formation. It includes feedback by SNII and SNIa using the Qij matrix
formalism. We also include a diffusion mechanism that spreads newly introduced
metals. The gas cooling rate depends on its specific composition. We study the
stellar populations of the resulting bulges finding a potential scenario where
they seem to be composed of two populations: an old, metal poor,
-enriched population, formed in a multiclump scenario at the beginning
of the simulation and a younger one, formed by slow accretion of satellites or
gas, possibly from the disk due to instabilities.Comment: 2 pages, 3 figures. Proceedings of IAUS 245 "Formation and Evolution
of Galaxy Bulges
Work, Risk and Health: Differences between Immigrants and Natives in Spain
We analyze the impact of working and contractual conditions, particularly exposure to job risks, on the probability of acquiring a disability. We postulate a model in which this impact is mediated by the choice of occupation, with a level of risk associated to it. We assume this choice is endogenous, and that it depends on preferences and opportunities in the labour market, both of which may differ between immigrants and natives. To test this hypothesis we use data from the Continuous Sample of Working Lives of the Spanish SS system. It contains individual, job and firm information of over a million workers, including a representative sample of immigrants. We find that risk exposure increases the probability of permanent disability by 5.3%; temporary employment also influences health. Migrant status – with differences among regions of origin – significantly affects both disability and the probability of being employed in a risky occupation. Most groups of immigrants work in riskier jobs, but have lower probability of becoming disabled. Nevertheless, our theoretical hypothesis that disability and risk are jointly determined is not valid for immigrants: i.e. for them working conditions is not a matter of choice in terms of health.disability, working conditions, immigration, Spain, MCVL
R-Band Imaging of Fields Around 1<z<2 Radiogalaxies
We have taken deep -band images of fields around five radiogalaxies:
0956+47, 1217+36, 3C256, 3C324 and 3C294 with . 0956+47 is found to
show a double nucleus. Our data on 1217+36 suggest the revision of its
classification as a radiogalaxy. We found a statistically significant excess of
bright () galaxies on scales of 2 arcmin around the radiogalaxies
(which have ) in our sample. The excess has been determined
empirically to be at level. It is remarkable that this excess
is not present for galaxies within the same area, suggesting that
the excess is not physically associated to the galaxies but due to intervening
groups and then related to gravitational lensing.Comment: 20 pages, uuencoded compressed PostScript including tables. Figures
available upon request. To appear in the March 1995 issue of The Astronomical
Journa
Assessment of unintentional islanding operations in distribution networks with large induction motors
This paper is aimed at assessing the impact of unintentional islanding operations (IOs) in the presence of large induction motors (IMs) within distribution networks (DNs). When a fault occurs,followingthecircuitbreaker(CB)faultclearing,theIMsacttransientlyasgenerators,duetoits inertia, until the CB reclosing takes place. The present work is the outcome of a project carried out in a small DN, where ¿eld measurements were recorded over two years. This paper provides a detailed description of the test system, a selected list of ¿eld measurements, and a discussion on modeling guidelinesusedtocreatethemodeloftheactualpowersystem. Themaingoalistovalidatethesystem model by comparing ¿eld measurements with simulation results. The comparison of simulations and ¿eld measurements prove the appropriateness of the modeling guidelines used in this work and highlight the high accuracy achieved in the implemented three-phase Matlab/Simulink modelPostprint (published version
A Unified Approach to the Very Fast Torque Control Methods for DC and AC Machines
(c) 2007 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.[EN] The general strategy to get a very fast torque control in a dc or ac machine is based on keeping the pulsational electromotive forces (EMFs) of all of its phases as small as possible during the transient states and achieving the torque changes by exclusively enhancing the rotational EMFs. All the resources available have to be oriented in this direction. This very simple but profound physical idea, when applied to dc or ac machines, allows the different control methods for these machines that have been developed to date and regarded as the best from a dynamic point of view to be deduced in a unified, systematic, and straightforward way.Serrano Iribarnegaray, L.; Martinez-Roman, J. (2007). A Unified Approach to the Very Fast Torque Control Methods for DC and AC Machines. IEEE Transactions on Industrial Electronics. 54(4):2047-2056. doi:10.1109/TIE.2007.895148S2047205654
Voluntary pre-trade anonymity and market liquidity
This paper analyses the effects on liquidity of voluntary pre-trade
anonymity in the trading process. We confirm previous studies showing
that market liquidity improves immediately after anonymous
trading. Using the daily percentage of effective volume traded anonymously,
we show that the anonymity–liquidity relationship presents
a non-linear U-shape. We focus on the voluntary concealment of
broker identification introduced by the Spanish Stock Exchange in
October 2015. We conclude that, in our sample, anonymity increases
stock liquidity but at a decreasing rate; when a considerable part of
the effective volume is traded anonymously, additional percentages
of anonymous trading deteriorates stock liquidity.This work was supported by the Comunidad de Madrid [S2015/HUM-3353 (EARLYFIN-CM)]; Ministerio de Ciencia y TecnologÃa [ECO2015-69205-P]; Ministerio de EconomÃa y Competitividad [ECO2014-51914-P]; Fondos FEDER [UNC315-EE-3636]; Basque Government [IT1336-19]
MOOC en nanotecnologÃa en la UA: Un ejemplo de innovación docente y tecnológica en QuÃmica Inorgánica
Las plataformas virtuales y herramientas on-line son parte de la vida cotidiana de los estudiantes que llenan nuestras aulas. El término web 2.0, introducido por O’Reilly y Dougherty en 2004, describe la transición de la web como una fuente de información a la web basada en comunidades de usuarios, con una gama especial de servicios y aplicaciones de internet que se modifica gracias a la participación social. La creación de comunidades on-line para mejorar la calidad del binomio enseñanza-aprendizaje es, por lo tanto, una herramienta útil para la educación superior. En este contexto, el Laboratorio de NanotecnologÃa Molecular de la UA ha desarrollado un proyecto educativo innovador, el primer MOOC (del inglés Massive On-line Open Course) sobre nanotecnologÃa en España. El objetivo de este curso es obtener una mejor comprensión de lo que es la nanotecnologÃa y su conexión con la vida real. El sitio web es la principal guÃa a través de los recursos y actividades del curso, dividido en diez unidades didácticas. El estudiante dispone, además, de una serie de herramientas gratuitas que descubrirá en las diferentes unidades, como vÃdeos, tutoriales, applets, etc. La única condición para acceder al curso es registrarse con una dirección de Gmail
Methodology to design a bottoming Rankine cycle, as a waste energy recovering system in vehicles. Study in a HDD engine
This article describes a methodology for the optimization of a bottoming cycle as a waste heat recovering system in vehicles. The methodology is applied to two particular cases in order to evaluate the preliminary energetic and technical feasibility of the implementation of a bottoming cycle in a heavy duty diesel (HDD) engine considering two different criteria. Initially, a study of the different waste heat sources of the engine is described. In this study, the power and exergy of each heat source is quantified, in order to evaluate which sources are suitable to be used in the bottoming cycle. The optimum working fluids to run the cycles are selected (water and R245fa). Then, the ideal Rankine cycle is optimized for the two different working fluids and different sets of heat sources (all the available heat sources and the sources with high exergy respectively) throughout the engine operating range, reaching a maximum improvement of 15% of the fuel consumption of the engine. Later, a study of the minimum temperature difference between the hot and cold flow of the heat exchangers is described. The improvements in fuel consumption and the size of the installed heat exchanger are related to this temperature difference. Finally, the non-ideal behavior of the machines (pump and expander) is analyzed, obtaining a maximum improvement of 10% in brake specific fuel consumption (bsfc).This work was partially funded by the "Programa de Formacion de Profesorado Universitario (FPU)", "Programa de Apoyo a la Investigacion y Desarrollo de la Universidad Politecnica de Valencia 2010", "Proyectos I + D para grupos de investigacion emergentes 2011" and "Programa de apoyo a la investigacion y desarrollo de la U.P.V (PAID-06-09)". The authors thank J. Dahlqvist for his help in improving the English grammar.Macian Martinez, V.; Serrano Cruz, JR.; Dolz Ruiz, V.; Sánchez Serrano, J. (2013). Methodology to design a bottoming Rankine cycle, as a waste energy recovering system in vehicles. Study in a HDD engine. Applied Energy. 104:758-771. https://doi.org/10.1016/j.apenergy.2012.11.075S75877110
The regulatory and Health Technology processes in Europe and drug market access. The case of cystic fibrosis
In order to reach the European market, a new drug needs to receive a positive evaluation regarding its quality, safety and efficacy by regulatory health authorities and also obtain a positive HTA appraisal regarding its cost-effectiveness by HTA bodies. Regulators and HTA bodies are collaborating in several projects at European level in order to harmonize the scientific requirements of both evaluations to the maximum extent possible. The comparison of the regulatory evaluation performed by EMA for Kalydeco and the HTA appraisals issued by several EU bodies exemplifies the dilemma between scientific evidence and local economic considerations and the difficulties in the achievement of harmonization and therefore equity in the access to drugs
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