Effects of mergers and galaxy interactions at intermediate densities in the SDSS-DR4

Recently, several observational works have provided evidence in favor of a pre-processing of galaxies at moderate environments. These evidences show that the transition of galaxies onto the red-sequence could take place in galaxy groups in the outskirt of clusters or in the infalling populations. Based on the evidence that interacting and merging systems are priviledged found at intermediate densities, we use the SDSSDR4 data to analyse the role of mergers and close galaxy interactions as environmental processes to lead to evolutionary transformations. We explore the properties of galaxy pairs and merging systems at different local and global density environments, comparing them with those of isolated galaxies in an unbiased control sample.Recientemente varios autores han aportado evidencia observacional que sugerir´ıa que las galaxias son pre-procesadas en regiones de densidad intermedia, produciendo una gran transformacion en las mismas. Estos resultados observacionales muestran que la transicion de las galaxias hacia la secuencia roja se producir´ıa en regiones perifericas de los cumulos de galaxias. Por otra parte, existe evidencia tanto teorica como observacional que indicar´ıa que las interacciones y fusiones de galaxias son particularmente frecuentes en estas regiones. En este trabajo analizamos el rol de las interacciones y colisiones de galaxias en regiones de densidad intermedia, utilizando para tal efecto galaxias del cat´alogo SDSS-DR4.Facultad de Ciencias Astronómicas y GeofísicasConsejo Nacional de Investigaciones Científicas y Técnica

Effects of mergers and galaxy interactions at intermediate densities in the SDSS-DR4

Recently, several observational works have provided evidence in favor of a pre-processing of galaxies at moderate environments. These evidences show that the transition of galaxies onto the red-sequence could take place in galaxy groups in the outskirt of clusters or in the infalling populations. Based on the evidence that interacting and merging systems are priviledged found at intermediate densities, we use the SDSSDR4 data to analyse the role of mergers and close galaxy interactions as environmental processes to lead to evolutionary transformations. We explore the properties of galaxy pairs and merging systems at different local and global density environments, comparing them with those of isolated galaxies in an unbiased control sample.Recientemente varios autores han aportado evidencia observacional que sugerir´ıa que las galaxias son pre-procesadas en regiones de densidad intermedia, produciendo una gran transformacion en las mismas. Estos resultados observacionales muestran que la transicion de las galaxias hacia la secuencia roja se producir´ıa en regiones perifericas de los cumulos de galaxias. Por otra parte, existe evidencia tanto teorica como observacional que indicar´ıa que las interacciones y fusiones de galaxias son particularmente frecuentes en estas regiones. En este trabajo analizamos el rol de las interacciones y colisiones de galaxias en regiones de densidad intermedia, utilizando para tal efecto galaxias del cat´alogo SDSS-DR4.Facultad de Ciencias Astronómicas y GeofísicasConsejo Nacional de Investigaciones Científicas y Técnica

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

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 $\Lambda$CDM 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

Aplicación de la topología molecular en la predicción de la inhibición de Trypanosoma cruzi Hexokinasa y un grupo de derivados bifosfonatos

A topological-mathematical model has been arranged to search for new derivatives of bisphosphonate compounds actingas inhibitors against Trypanosoma cruzi hexokinase. By using linear discriminant analysis, a four-variable function wasachieved allowing an accurate prediction of the IC50 for each compound of the training and test series. After carryingout a virtual screening based upon such a model, new structures potentially actives against T. cruzi are proposedSe ha desarrollado un modelo topológico-matemático para la búsqueda de nuevos derivados bisfosfonatos activosfrente a la hexokinasa de Trypanosoma cruzi. Utilizando el análisis lineal discriminante se ha seleccionado una funcióncon cuatro variables capaz de predecir adecuadamente la CI50 para cada compuesto de las series de entrenamientoy test. El modelo propuesto se ha aplicado a una librería molecular y se han propuesto nuevas estructuraspotencialmente activas frente a T. cruzi

Application of molecular topology to the prediction of inhibition of Trypanosoma cruzi Hexokinase by bisphosphonates

Se ha desarrollado un modelo topológico-matemático para la búsqueda de nuevos derivados bisfosfonatos activos frente a la hexokinasa de Trypanosoma cruzi. Utilizando el análisis lineal discriminante se ha seleccionado una función con cuatro variables capaz de predecir adecuadamente la CI50 para cada compuesto de las series de entrenamiento y test. El modelo propuesto se ha aplicado a una librería molecular y se han propuesto nuevas estructuras potencialmente activas frente a T. cruzi.A topological-mathematical model has been arranged to search for new derivatives of bisphosphonate compounds acting as inhibitors against Trypanosoma cruzi hexokinase. By using linear discriminant analysis, a four-variable function was achieved allowing an accurate prediction of the IC50 for each compound of the training and test series. After carrying out a virtual screening based upon such a model, new structures potentially actives against T. cruzi are proposed.Este trabajo ha sido posible gracias al Fondo de Investigación Sanitaria, Ministerio de Sanidad, España (proyecto SAF2005-PIO52128) y al Máster Internacional en Enfermedades Parasitarias Tropicales, Universidad de Valencia

Optical spectroscopy of 4U 1812-12: an ultra-compact X-ray binary seen through an H II region

The persistent, low-luminosity neutron star X-ray binary 4U 1812-12 is a potential member of the scarce family of ultra-compact systems. We performed deep photometric and spectroscopic optical observations with the 10.4 m Gran Telescopio Canarias in order to investigate the chemical composition of the accreted plasma, which is a proxy for the donor star class. We detect a faint optical counterpart (g~25, r~23) that is located in the background of the outskirts of the Sharpless 54 H II region, whose characteristic nebular lines superimpose on the X-ray binary spectrum. Once this is corrected for, the actual source spectrum lacks hydrogen spectral features. In particular, the Halpha emission line is not detected, with an upper limit (3 sigma) on the equivalent width of <1.3 A. Helium (He I) lines are neither observed, albeit our constraints are not restrictive enough to properly test the presence of this element. We also provide stringent upper limits on the presence of emission lines from other elements, such as C and O, which are typically found in ultra-compact systems with C-O white dwarfs donors. The absence of hydrogen features, the persistent nature of the source at low luminosity, as well as the low optical to X-ray flux ratio confirm 4U 1812-12 as a compelling ultra-compact X-ray binary candidate, for which we tentatively propose a He-rich donor based on the optical spectrum and the detection of short thermonuclear X-ray bursts. In this framework, we discuss the possible orbital period of the system according to disc instability and evolutionary models.Comment: Accepted for publication in A&

Handbook of successful open teaching practices

The document presents 24 open teaching practices, with the aim to inspire teachers to adopt open approaches, as well as an original competences framework for Open Education.Erasmus +info:eu-repo/semantics/publishedVersio

Estudio comparativo de la eficacia del índice de masa corporal y el porcentaje de grasa corporal como métodos para el diagnóstico de sobrepeso y obesidad en población pediátrica

La OMS considera la obesidad como uno de los problemas de salud pública más importantes en el mundo, especialmente entre la población infantil y juvenil. Según esto, resulta prioritario mejorar y profundizar en el estudio de las diferentes metodologías de diagnóstico y valoración del estado nutricional en población pediátrica y adolescente. Actualmente, son utilizados como indicadores del estado nutricional el índice de masa corporal y el porcentaje de grasa corporal. Ahora bien, respecto del segundo, existe cierta controversia por considerar que tiende a sobreestimar el sobrepeso y la obesidad. Los objetivos a alcanzar con el desarrollo de este estudio fueron determinar la prevalencia de sobrepeso y obesidad en una población de escolares de entre 9 y 17 años de edad pertenecientes a 13 centros educativos de la ciudad de Granada y provincia. En segundo lugar, verificar posibles diferencias significativas a nivel de la precisión del índice de masa corporal y el porcentaje de grasa corporal para diagnosticar sobrepeso y obesidad.The World Health Organization (WHO) regards obesity as one of the most serious public health problems in the world that can affect young children and adolescents. Accordingly, a major priority is to find ways to more effectively study and analyze the various methods used to diagnose and evaluate the nutritional state of the pediatric and adolescent population. The nutritional indicators currently employed for this purpose are the body mass index and body-fat percentage. However, there is a certain controversy related to the body-fat percentage since it tends to overestimate overweight and obesity. The main objectives of this study were the following: (i) to determine the prevalence of overweight and obesity in a population of primary and secondary school children between 9-17 years of age at 13 educational centers in the city and province of Granada; (ii) to verify possible differences regarding the accuracy of the body mass index and the body-fat percentage in the diagnosis of overweight and obesity

A novel Chilean salmon fish backbone-based nanoHydroxyApatite functional biomaterial for potential use in bone tissue engineering

IntroductionGiven the ensuing increase in bone and periodontal diseases and defects, de novo bone repair and/or regeneration strategies are constantly undergoing-development alongside advances in orthopedic, oro-dental and cranio-maxillo-facial technologies and improvements in bio−/nano-materials. Indeed, there is a remarkably growing need for new oro-dental functional biomaterials that can help recreate soft and hard tissues and restore function and aesthetics of teeth/ dentition and surrounding tissues. In bone tissue engineering, HydroxyApatite minerals (HAp), the most stable CaP/Calcium Phosphate bioceramic and a widely-used material as a bone graft substitute, have been extensively studied for regenerative medicine and dentistry applications, including clinical use. Yet, limitations and challenges owing principally to its bio-mechanical strength, exist and therefore, research and innovation efforts continue to pursue enhancing its bio-effects, particularly at the nano-scale.MethodsHerein, we report on the physico-chemical properties of a novel nanoHydroxyApatite material obtained from the backbone of Salmon fish (patent-pending); an abundant and promising yet under-explored alternative HAp source. Briefly, our nanoS-HAp obtained via a modified and innovative alkaline hydrolysis–calcination process was characterized by X-ray diffraction, electron microscopy, spectroscopy, and a cell viability assay.Results and DiscussionWhen compared to control HAp (synthetic, human, bovine or porcine), our nanoS-HAp demonstrated attractive characteristics, a promising biomaterial candidate for use in bone tissue engineering, and beyond