900 research outputs found

    Calibration of semi-analytic models of galaxy formation using Particle Swarm Optimization

    Get PDF
    We present a fast and accurate method to select an optimal set of parameters in semi-analytic models of galaxy formation and evolution (SAMs). Our approach compares the results of a model against a set of observables applying a stochastic technique called Particle Swarm Optimization (PSO), a self-learning algorithm for localizing regions of maximum likelihood in multidimensional spaces that outperforms traditional sampling methods in terms of computational cost. We apply the PSO technique to the SAG semi-analytic model combined with merger trees extracted from a standard Λ\LambdaCDM N-body simulation. The calibration is performed using a combination of observed galaxy properties as constraints, including the local stellar mass function and the black hole to bulge mass relation. We test the ability of the PSO algorithm to find the best set of free parameters of the model by comparing the results with those obtained using a MCMC exploration. Both methods find the same maximum likelihood region, however the PSO method requires one order of magnitude less evaluations. This new approach allows a fast estimation of the best-fitting parameter set in multidimensional spaces, providing a practical tool to test the consequences of including other astrophysical processes in SAMs.Comment: 11 pages, 4 figures, 1 table. Accepted for publication in ApJ. Comments are welcom

    Design of a band-pass sigma-delta modulator with reduced number of opamps

    Get PDF
    This paper is intended to compare the performance of a Band-Pass converter structure and its Low-Pass prototype 2nd order Sigma-Delta Analog to Digital converter. For this purpose Matlab simulations for the 4th order Band-Pass converter have been performed and its power consumption calculated when using the equivalent Op-Amp used m the Low-Pass modulator. First of all will be described the method used to calculate the transfer function and, thus the structure of the Band-Pass structure to be tested. After a band-pass transfer function has been obtained it is implemented using reduced number of opamps. This topology is compared to the existing ones and a system level simulation and characterisation is performed. Finally, jitter limitations are studied. Transistor level simulations using Spectre have been done in order to validate MATLAB simulations prior to layout design

    Controlled grain-size thermochromic VO2 coatings by the fast oxidation of sputtered vanadium or vanadium oxide films deposited at glancing angles

    Get PDF
    An original, simple and cost-effective oxidation strategy to attain thermochromic vanadium dioxide thin films is reported. This two-step procedure comprises the initial deposition of DC magnetron-sputtered vanadium or vanadium oxide films by the combination of glancing angle deposition and, if needed, reactive gas pulsing process, followed by fast oxidation of such layers in air atmosphere at high temperatures. Thanks to the careful control of the thermal treatment parameters, and taking advantage of the superior reactivity of the high surface-to-volume porous deposited structures, the formation of pure VO2 (M1) layers was achieved. The comprehensive characterization of such oxidized systems by means of scanning electron microscopy, Raman spectroscopy and scanning-transmission electron microscopy techniques such as electron energy-loss spectroscopy, not only confirmed the presence of the VO2 (M1) phase, but also allowed to shed light on the key role that reaction time plays in the selective formation of vanadium dioxide films of adjustable grain size and crystallinity. The optimal conditions to stabilize thermochromic VO2 consists in using large deposition angles (85 degrees) and short oxygen pulses (<= 2 s) during the growth, followed by fast and short thermal treatments (<= 45 s with a heating rate of 42 degrees C s(-1)) in air atmosphere at 550 degrees C. The metal-to-insulator response of the accomplished VO2 layers was finally evaluated by means of temperature dependent Kelvin probe force microscopy measurements, evidencing surface potential drops at heating, greater than those reported in the literature to date for VO2 thin films.A. J. Santos would like to thank the IMEYMAT Institute and the Spanish Ministerio de Educacion y Cultura for the concessions of grants (ICARO-173873 and FPU16-04386) . The "Talent Attraction Program" of the University of Cadiz is acknowledged by supporting B. Lacroix contract code E-11-2017-0117214. University of Cadiz and IMEYMAT are also agreed by financing the mutual facilities available at the UCA R&D Central Services (SC-ICYT) , the UCA projects reference "PUENTE PR2018-040 '' and "PUENTE PR2020-003 '', and the IMEYMAT project references "LINEAS PRIORITARIAS PLP2019120-3 and PLP2021120-1 ''. This work was supported by the Spanish State R&D project (Retos y Generacion de Conocimiento) ref. PID2020-114418RB-I00/AEI/10.13039/501100011033. The regional government of Andalusia with FEDER cofunding also participates through the projects AT-5983 Trewa 1157178 and FEDER-UCA18-10788. M. Dominguez acknowledges financial support from the Spanish Ministerio de Ciencia e Innovacion under project reference EQC 2018-004704-P FEDER 2014-2020, "Modernizacion del Servicio de Microscopia de Fuerza Atomica (AFM) del IMEYMAT"

    Simulación de un enfriador híbrido alimentado por energía solar térmica

    Get PDF
    CIES2020 - XVII Congresso Ibérico e XIII Congresso Ibero-americano de Energia SolarRESUMEN: En este trabajo se presenta la modelación y simulación de un enfriador híbrido compresión/absorción alimentado por un concentrador solar de disco parabólico. El enfriamiento producido por este sistema se utiliza para aire acondicionado de una vivienda. El estudio fue realizado mediante balances de energía y de masa, en cada componente de los sistemas de refrigeración y del sistema solar. La transferencia de calor por convección y por radiación también fueron considerados. Los resultados muestran que la carga proporcionada por el sistema de compresión es 20% mayor que el alimentado por el sistema de absorción. Aunque el sistema de absorción opera al 40% de la carga total requerida en el espacio a condicionar, requiere en torno a 40% más energía térmica que el sistema de compresión. Pueden obtenerse temperaturas cercanas a 1050 °C y 400 °C con relación de concentración de 20 y radiación solar de 600W/m2 respectivamente. La eficiencia del colector solar es 0.4 (40%) cuando la temperatura exterior es 35 °C a baja radiación de 200 W/m2.RESUMO: This paper presents the modeling and simulation of a compression/absorption hybrid chiller driven by a solar dish collector. The cooling produced by this system is used for air conditioning in a home. The study was carried out using energy and mass balances in each component of the cooling systems and the solar system. Convection and radiation heat transfer were also considered. The results show that the load provided by the compression system is 20% greater than that fed by the absorption system. Although the absorption system operates at 40% of the total load required in the space to be conditioned, it requires around 40% more thermal energy than the compression system. Temperatures close to 1050 °C and 400 °C can be obtained in concentration ratio of 20 and solar radiation of 600W/m2 respectively. Efficiency of the solar collector is 0.4 (40%) when the outdoor temperature is 35 °C at a low radiation of 200 W/m2.info:eu-repo/semantics/publishedVersio

    A strategic reflection for the management and implementation of CAR-T therapy in Spain: an expert consensus paper

    Get PDF
    CAR-T cell therapy represents a therapeutic revolution in the prognosis and treatment of patients with certain types of hematological cancer. However, they also pose new challenges in the healthcare, regulatory and financial fields. The aim of the RET-A project was to undertake a strategic reflection on the management of CAR-T therapies within the Spanish National Health System, to agree on recommendations that will help to better deal with the new context introduced by these cell therapies in the present and in the future. This think tank involved 40 key agents and opinion leaders. The experts identified three great challenges for implementing advanced therapies in Spain: therapeutic individualisation, with a multidisciplinary approach; acceleration of access times, by minimizing bureaucracy; and increase in the number of centers qualified to manage the CAR-T therapies in the NHS. The experts agreed on the ideal criteria for designating those qualified centers. They also agreed on a comprehensive CAR-T care pathway with the timings and roles which would ideally be involved in each part of the process.This study was funded by Gilead Sciences, Inc.Peer reviewe

    The CaT strength in Seyfert nuclei revisited: analyzing young stars and non-stellar light contributions to the spectra

    Get PDF
    In a former paper (Garcia-Rissmann et al. 2005; hereafter Paper I), we have presented spectra of 64 active, 9 normal and 5 Starburst galaxies in the region around the near-IR Calcium triplet absorption lines and the [SIII]9069 line. In the present paper we analyze the CaT strength (WCaT), and kinematical products derived in that study, namely stellar and ionized gas velocity dispersions. Our main results may be summarized as follows: (1) Seyfert 2s show no sign of dilution in WCaT with respect to the values spanned by normal galaxies, even when optical absorption lines such as the CaII K band at 3933 A are much weaker than in old, bulge-like stellar populations. (2) The location of Seyfert 2s in the WCaT-WCaK plane is consistent with evolutionary synthesis models. The implication is that the source responsible for the dilution of optical lines in these AGN is a young stellar population, rather than an AGN featureless continuum, confirming the conclusion of the pioneer study of Terlevich, Diaz & Terlevich. (3) In Seyfert 1s, both W[SIII] and WCaT tend to be diluted due to the presence of a non-stellar component, in agreement with the unification paradigm. (4) A comparison of stellar and gas velocity dispersions confirms the existence of a correlation between the typical velocities of stars and clouds of the Narrow Line Region. The strength and scatter around this correlation are similar to those previously obtained from the [OIII]5007 line width.Comment: 14 pages, 15 figures. Paper accepted for publication in MNRA

    Psicoterapia contemporánea: dilemas y perspectivas

    Get PDF
    Hablar de una psicoterapia contemporánea nos conduce necesariamente a abordajes en clave de complejidad que favorezcan miradas más abiertas, con más posibilidades, en su constitución, su ámbito de conocimiento, el ejercicio profesional y la formación de psicoterapeutas. Y pensarla desde una perspectiva interdisciplinar es fundamental para la comprensión, el análisis y las posibilidades de tratamiento de los problemas psicológicos que aquejan a las sociedades contemporáneas. Este es el planteamiento central que se desarrolla en esta obra conformada por ocho ensayos, en los cuales se abordan temas como la formación de los psicoterapeutas, la historia de este campo profesional, la influencia del entorno y de la familia en el consultante, así como la importancia del diálogo con otras disciplinas para el perfeccionamiento de este campo de generación e innovación en psicoterapia. Por ello, se recomienda la lectura de este volumen, el primero de la colección Psicoterapia y Diálogo Interdisciplinario, a estudiantes, docentes y profesionales en el campo de la psicoterapia y la salud mental, ya que este ejercicio profesional cobra cada día mayor relevancia para el entendimiento y abordaje de la complejidad de la vida humana hacia la promoción del bienestar.ITESO. A.C

    Molecular epidemiology, phylogeny, and phylodynamics of CRF63_02A1, a recently originated HIV-1 circulating recombinant form spreading in Siberia

    Get PDF
    The HIV-1 epidemic in Russia is dominated by the former Soviet Union subtype A (A(FSU)) variant, but other genetic forms are circulating in the country. One is the recently described CRF63_02A1, derived from recombination between a CRF02_AG variant circulating in Central Asia and A(FSU), which has spread in the Novosibirsk region, Siberia. Here we phylogenetically analyze pol and env segments from 24 HIV-1 samples from the Novosibirsk region collected in 2013, with characterization of three new near full-length genome CRF63_02A1 sequences, and estimate the time of the most recent common ancestor (tMRCA) and the demographic growth of CRF63_02A1 using a Bayesian method. The analyses revealed that CRF63_02A1 is highly predominant in the Novosibirsk region (81.2% in pol sequences) and is transmitted both among injecting drug users and by heterosexual contact. Similarity searches with database sequences combined with phylogenetic analyses show that CRF63_02A1 is circulating in East Kazakhstan and the Eastern area of Russia bordering China. The analyses of near full-length genome sequences show that its mosaic structure is more complex than reported, with 18 breakpoints. The tMRCA of CRF63_02A1 was estimated around 2006, with exponential growth in 2008-2009 and subsequent stabilization. These results provide new insights into the molecular epidemiology, phylogeny, and phylodynamics of CRF63_02A1.We thank the personnel at the Genomic Unit of Instituto de Salud Carlos III, Majadahonda, Madrid, Spain, for technical assistance in sequencing, and Bonnie Mathieson, from the Office of AIDS Research, National Institutes of Health, Bethesda, Maryland for her support of this study. This work was funded by Office of AIDS Research, National Institutes of Health, through the training program “Molecular Epidemiology of HIV-1 in Eastern Europe and Its Significance for Vaccine Development.”S

    Effect of β-Glucans in Diets on Growth, Survival, Digestive Enzyme Activity, and Immune System and Intestinal Barrier Gene Expression for Tropical Gar (Atractosteus tropicus) Juveniles

    Get PDF
    The application of β-1,3/1,6-glucan derived from yeast at five concentrations (0%, 0.5%, 1.0%, 1.5%, and 2.0%) in formulated diets was evaluated in juveniles for its effects on the growth, survival, digestive enzymatic activity, and expression of genes associated with the immune system (interlukin-10 (IL-10), transforming growth factor (TGF), occludin (OCC), mucin2 (MUC2), lysozyme (LYS), and nucleotide-binding and oligomerization domain 2 (NOD2)) in tropical gar (Atractosteus tropicus). For the experiment, three replicates of 30 fish per experimental unit (70 L) were cultivated for 62 days. The growth results showed no statistically significant differences in relation to weight and total length between treatments. The activity of digestive enzymes (alkaline proteases, trypsin, leucine aminopeptidase, and amylase) did not show significant differences between treatments, except for chymotrypsin activity, where fish fed 1.0% and 1.5% of β-glucans showed higher activities compared with the rest of the treatments. On the other hand, the analysis of gene expression did not show significant differences between treatments, although a tendency of increase in the expression of IL-10, TGF, MUC2, and OCC was observed with an addition of 1.5% of the prebiotic, but there was a decrease in the fish fed with 2% of the prebiotic. It is possible to include concentrations of between 0.5% and 1.5% of β-glucans in the diets for A. tropicus, with no detectable adverse effects on growth, survival, digestive enzyme activity, or specific gene expression. β-glucan 1,3/1,6 added at 1.0% and 1.5% in the diet significantly increases chymotrypsin activity.info:eu-repo/semantics/publishedVersio
    corecore