Small batch deep reinforcement learning

In value-based deep reinforcement learning with replay memories, the batch size parameter specifies how many transitions to sample for each gradient update. Although critical to the learning process, this value is typically not adjusted when proposing new algorithms. In this work we present a broad empirical study that suggests {\em reducing} the batch size can result in a number of significant performance gains; this is surprising, as the general tendency when training neural networks is towards larger batch sizes for improved performance. We complement our experimental findings with a set of empirical analyses towards better understanding this phenomenon.Comment: Published at NeurIPS 202

The nature of GRB-selected submillimeter galaxies: hot and young

We present detailed fits of the spectral energy distributions (SEDs) of four submillimeter (submm) galaxies selected by the presence of a gamma-ray burst (GRB) event (GRBs 980703, 000210, 000418 and 010222). These faint ~3 mJy submm emitters at redshift ~1 are characterized by an unusual combination of long- and short-wavelength properties, namely enhanced submm and/or radio emission combined with optical faintness and blue colors. We exclude an active galactic nucleus as the source of long-wavelength emission. From the SED fits we conclude that the four galaxies are young (ages <2 Gyr), highly starforming (star formation rates ~150 MSun/yr), low-mass (stellar masses ~10^10 MSun) and dusty (dust masses ~3x10^8 MSun). Their high dust temperatures (Td>45 K) indicate that GRB host galaxies are hotter, younger, and less massive counterparts to submm-selected galaxies detected so far. Future facilities like Herschel, JCMT/SCUBA-2 and ALMA will test this hypothesis enabling measurement of dust temperatures of fainter GRB-selected galaxies.Comment: 9 pages, 2 figures, submitted to ApJ, for SED templates, see http://archive.dark-cosmology.dk

Optical afterglows of gamma-ray bursts: a bimodal distribution?"

The luminosities of the optical afterglows of Gamma Ray Bursts, 12 hours (rest frame time) after the trigger, show a surprising clustering, with a minority of events being at a significant smaller luminosity. If real, this dichotomy would be a crucial clue to understand the nature of optically dark afterglows, i.e. bursts that are detected in the X-ray band, but not in the optical. We investigate this issue by studying bursts of the pre-Swift era, both detected and undetected in the optical. The limiting magnitudes of the undetected ones are used to construct the probability that a generic bursts is observed down to a given magnitude limit. Then, by simulating a large number of bursts with pre-assigned characteristics, we can compare the properties of the observed optical luminosity distribution with the simulated one. Our results suggest that the hints of bimodality present in the observed distribution reflects a real bimodality: either the optical luminosity distributions of bursts is intrinsically bimodal, or there exists a population of bursts with a quite significant grey absorption, i.e. wavelength independent extinction. This population of intrinsically weak or grey-absorbed events can be associated to dark bursts.Comment: 10 pages, 5 figures, accepted for publication in MNRA

Bigger, Better, Faster: Human-level Atari with human-level efficiency

We introduce a value-based RL agent, which we call BBF, that achieves super-human performance in the Atari 100K benchmark. BBF relies on scaling the neural networks used for value estimation, as well as a number of other design choices that enable this scaling in a sample-efficient manner. We conduct extensive analyses of these design choices and provide insights for future work. We end with a discussion about updating the goalposts for sample-efficient RL research on the ALE. We make our code and data publicly available at https://github.com/google-research/google-research/tree/master/bigger_better_faster.Comment: ICML 2023 Camera Read

Labor conditions of a group of social work graduates from the northern subregion of Valle del Cauca, Colombia

Este artículo presenta los resultados de una investigación descriptiva, desarrollada bajo una metodología mixta, cuyo objeto fue analizar la situación laboral de un grupo de egresados de Trabajo Social. Se aplicó una encuesta aleatoria a 62 personas para indagar sobre las principales tendencias en relación a sus condiciones laborales y 16 entrevistas semiestructuradas que, a través de un proceso de análisis de contenido, señaló las principales limitaciones para el ejercicio profesional y sus formas de afrontamiento. Frente a las condiciones laborales se encontró que comportan características propias de un mercado laboral atravesado por la flexibilización, tercerización y precariedad laboral propios del mundo del trabajo y de los procesos de privatización de los servicios sociales. Con relación a los aspectos que condicionan y limitan el desarrollo de la intervención profesional, se halló excesiva carga laboral, inestabilidad por contratos de corto plazo, sumado al cumplimiento de múltiples trámites administrativos, bajos presupuestos para inversión social, concepciones asistencialistas y cuantificadoras de la intervención, así como dificultades en los equipos para el trabajo interdisciplinario, inexperiencia profesional por alta rotación laboral, demandas por fuera del quehacer profesional y reducido tiempo para desarrollar la intervención; aspectos que afectan la vida personal y laboral de los y las egresadas.This article presents the results of a descriptive research, developed under a mixed methodology, whose purpose was to analyze the labor situation of a group of Social Work graduates. A random survey was applied to 62 people, to inquire about the main trends in relation to their working conditions and 16 semi-structured interviews, which through a process of content analysis, pointed out the main limitations for the professional practice and their ways of coping. Regarding working conditions, it was found that they involve characteristics of a labor market characterized by flexibilization, outsourcing and labor precariousness typical of the world of work and of the privatization processes of social services. In relation to the aspects that condition and limit the development of professional intervention, we found an excessive workload, instability due to short-term contracts, in addition to compliance with multiple administrative procedures, low budgets for social investment, assistance and quantifying conceptions of intervention, as well as difficulties in the teams for interdisciplinary work, professional inexperience due to high labor turnover, demands outside the professional work and reduced time to develop the intervention; aspects that affect the personal and working life of the graduates

On the Afterglow of the X-ray Flash of 2003 July 23: Photometric evdence for an Off-Axis Gamma-Ray burst with an Associated Supernova

Peer reviewe

Condiciones laborales de un grupo de egresados de Trabajo Social de la subregión norte del Valle del Cauca, Colombia

Este artículo presenta los resultados de una investigación descriptiva, desarrollada bajo una metodología mixta, cuyo objeto fue analizar la situación laboral de un grupo de egresados de Trabajo Social. Se aplicó una encuesta aleatoria a 62 personas para indagar sobre las principales tendencias en relación a sus condiciones laborales y 16 entrevistas semiestructuradas que, a través de un proceso de análisis de contenido, señaló las principales limitaciones para el ejercicio profesional y sus formas de afrontamiento. Frente a las condiciones laborales se encontró que comportan características propias de un mercado laboral atravesado por la flexibilización, tercerización y precariedad laboral propios del mundo del trabajo y de los procesos de privatización de los servicios sociales. Con relación a los aspectos que condicionan y limitan el desarrollo de la  intervención profesional, se halló excesiva carga laboral, inestabilidad por contratos de corto plazo, sumado al cumplimiento de múltiples trámites administrativos, bajos presupuestos para inversión social, concepciones asistencialistas y cuantificadoras de la intervención, así como dificultades en los equipos para el trabajo interdisciplinario, inexperiencia profesional por alta rotación laboral, demandas por fuera del quehacer profesional y reducido tiempo para desarrollar la  intervención; aspectos que afectan la vida personal y laboral de los egresados

Condiciones laborales de un grupo de egresados de Trabajo Social de la subregión norte del Valle del Cauca, Colombia

This article presents the results of a descriptive research, developed under a mixed methodology, whose purpose was to analyze the labor situation of a group of Social Work graduates. A random survey was applied to 62 people, to inquire about the main trends in relation to their working conditions and 16 semi-structured interviews, which through a process of content analysis, pointed out the main limitations for the professional practice and their ways of coping. Regarding working conditions, it was found that they involve characteristics of a labor market characterized by flexibilization, outsourcing and labor precariousness typical of the world of work and of the privatization processes of social services. In relation to the aspects that condition and limit the development of professional intervention, we found an excessive workload, instability due to short-term contracts, in addition to compliance with multiple administrative procedures, low budgets for social investment, assistance and quantifying conceptions of intervention, as well as difficulties in the teams for interdisciplinary work, professional inexperience due to high labor turnover, demands outside the professional work and reduced time to develop the intervention; aspects that affect the personal and working life of the graduates.Este artículo presenta los resultados de una investigación descriptiva, desarrollada bajo una metodología mixta, cuyo objeto fue analizar la situación laboral de un grupo de egresados de Trabajo Social. Se aplicó una encuesta aleatoria a 62 personas para indagar sobre las principales tendencias en relación a sus condiciones laborales y 16 entrevistas semiestructuradas que, a través de un proceso de análisis de contenido, señaló las principales limitaciones para el ejercicio profesional y sus formas de afrontamiento. Frente a las condiciones laborales se encontró que comportan características propias de un mercado laboral atravesado por la flexibilización, tercerización y precariedad laboral propios del mundo del trabajo y de los procesos de privatización de los servicios sociales. Con relación a los aspectos que condicionan y limitan el desarrollo de la  intervención profesional, se halló excesiva carga laboral, inestabilidad por contratos de corto plazo, sumado al cumplimiento de múltiples trámites administrativos, bajos presupuestos para inversión social, concepciones asistencialistas y cuantificadoras de la intervención, así como dificultades en los equipos para el trabajo interdisciplinario, inexperiencia profesional por alta rotación laboral, demandas por fuera del quehacer profesional y reducido tiempo para desarrollar la  intervención; aspectos que afectan la vida personal y laboral de los egresados

The very red afterglow of GRB 000418 - further evidence for dust extinction in a GRB host galaxy

We report near-infrared and optical follow-up observations of the afterglow of the Gamma-Ray Burst 000418 starting 2.5 days after the occurrence of the burst and extending over nearly seven weeks. GRB 000418 represents the second case for which the afterglow was initially identified by observations in the near-infrared. During the first 10 days its R-band afterglow was well characterized by a single power-law decay with a slope of 0.86. However, at later times the temporal evolution of the afterglow flattens with respect to a simple power-law decay. Attributing this to an underlying host galaxy we find its magnitude to be R=23.9 and an intrinsic afterglow decay slope of 1.22. The afterglow was very red with R-K=4 mag. The observations can be explained by an adiabatic, spherical fireball solution and a heavy reddening due to dust extinction in the host galaxy. This supports the picture that (long) bursts are associated with events in star-forming regions.Comment: Accepted for publication in The Astrophysical Journal. 12 pages; citations & references updated; minor textual change

Contrasting effects of aliskiren versus losartan on hypertensive vascular remodeling

Background: Hyperactivation of the renin-angiotensin system contributes to hypertension-induced upregulation of vascular matrix metalloproteinases (MMPs) and remodeling, especially in the two kidney, one clip (2K1C) hypertension model. We hypothesized that the AT(1)R antagonist losartan or the renin inhibitor aliskiren, given at doses allowing similar antihypertensive effects, could prevent in vivo vascular MMPs upregulation and remodeling, and collagen/elastin deposition found in 2K1C hypertension by preventing the activation of extracellular signal-regulated kinase 1/2 (ERK 1/2) and transforming growth factor-beta(1) (TGF-beta(1)). We also hypothesized that aliskiren could enhance the effects of losartan.Methods: 2K1C rats were treated with aliskiren (50 mg.kg(-1).day(-1)), or losartan (10 mg.kg(-1).day(-1)), or both by gavage during 4 weeks.Results: Aliskiren, losartan, or both drugs exerted similar antihypertensive effects when compared with 2K1C rats treated with water. Aliskiren reduced plasma renin activity in both sham and 2K-1C rats. Losartan alone or combined with aliskiren, but not aliskiren alone, abolished 2K1C-induced aortic hypertrophy and hyperplasia, and prevented the increases in aortic collagen/elastin content, MMP-2 levels, gelatinolytic activity, and expression of phospho-ERK 1/2 and TGF-beta(1). No significant differences were found in the aortic expression of the (pro) renin receptor.Conclusions: These findings show that although losartan and aliskiren exerted similar antihypertensive effects, only losartan prevented the activation of vascular profibrotic mechanisms and MMP upregulation associated with vascular remodeling in 2K1C hypertension. Our findings also suggest that aliskiren does not enhance the protective effects exerted by losartan. (C) 2012 Elsevier Ireland Ltd. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Univ São Paulo, Fac Med Ribeirao Preto, Dept Pharmacol, BR-14049900 Ribeirao Preto, SP, BrazilUniv São Paulo, Fac Med Ribeirao Preto, Dept Biochem & Immunol, BR-14049900 Ribeirao Preto, SP, BrazilUniversidade Federal de São Paulo, Dept Med, Div Nephrol, São Paulo, BrazilUniv São Paulo, Dent Sch Ribeirao Preto, Dept Morphol Estomatol & Physiol, BR-14049900 Ribeirao Preto, SP, BrazilUniversidade Federal de São Paulo, Dept Med, Div Nephrol, São Paulo, BrazilWeb of Scienc