Massive star formation in Wolf-Rayet galaxies. IV: Colours, chemical composition analysis and metallicity-luminosity relations

(Abridged) We performed a multiwavelength analysis of a sample of starburst galaxies that show the presence of a substantial population of very young massive (WR) stars. Here we present the global analysis of the derived photometric and chemical properties. We compare optical/NIR colours and the physical properties (reddening coefficient, equivalent widths of the emission and underlying absorption lines, ionization degree, electron density, and electron temperature) and chemical properties with previous observations and galaxy evolution models. Attending to their absolute B-magnitude many of them are not dwarf galaxies, but they should be during their quiescent phase. We found that both C(Hb) and Wabs increase with increasing metallicity. We detected a high N/O ratio in objects showing strong WR features. The ejecta of the WR stars may be the origin of the N enrichment in these galaxies. We compared the abundances provided by the direct method with those obtained using empirical calibrations, finding that (i) the Pilyugin method is the best suitable empirical calibration, (ii) the relations between the oxygen abundance and the N2 or the O3N2 parameters provided by Pettini & Pagel (2004) give acceptable results for objects with 12+log(O/H)>8.0, and (iii) the results provided by empirical calibrations based on photoionization models are systematically 0.2-0.3 dex higher than the values derived from the direct method. The O and N abundances and the N/O ratios are related to the optical/NIR luminosity; the dispersion is consequence of the differences in the star-formation histories. Galaxies with redder colours tend to have higher oxygen and nitrogen abundances. Our detailed analysis is fundamental to understand the nature of galaxies showing strong starbursts, as well as to know their star formation history and the relationships with the environment.Comment: 30 pages, 22 figures, accepted to A&A. Updated with the final version

Confusiones de interpretación en Mecánica Cuántica elemental

Quantum Mechanics is a fundamental physical theory about atomic-scale processes. It was built between 1920 and 1940 by the most distinguished physicists of that time. The accordance between the predictions of the theory and experimental results is remarkable. The physical interpretation of its mathematical constructs, however, raised unprecedented controversies. Ontological, semantic, and epistemic vagueness abound in the orthodox interpretations and have resulted in serious misunderstandings that are often repeated in textbooks and elsewhere. In this work, we identify, criticize, and clarify the most spread ones.La Mecánica Cuántica es una teoría de física fundamental que modela procesos a escalas atómicas. La teoría fue formulada entre los años 1920 y 1940. El acuerdo entre las predicciones de su formalismo matemático y los resultados experimentales es notable. Sin embargo, las interpretaciones físicas de sus constructos originaron controversias sin precedentes en la historia de la Física. Las imprecisiones ontológicas, semánticas y epistémicas de las distintas interpretaciones han ocasionado que se repitan y propaguen graves malentendidos que obstaculizan la investigación básica. En este trabajo identificaremos, criticaremos y aclararemos filosóficamente algunas de estas confusiones, con énfasis en las más básicas y difundidas.Fil: Lopez Armengol, Federico Gaston. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Romero, Gustavo Esteban. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; Argentin

The tidally disturbed luminous compact blue galaxy Mkn 1087 and its surroundings

We present new broad-band optical and near-infrared CCD imaging together with deep optical intermediate-resolution spectroscopy of Mkn 1087 and its surrounding objects. We analyze the morphology and colors of the stellar populations of the brightest objects, some of them star-formation areas, as well as the kinematics, physical conditions and chemical composition of the ionized gas associated with them. Mkn 1087 does not host an Active Galactic Nucleus, but it could be a Luminous Compact Blue Galaxy. Although it was classified as a suspected Wolf-Rayet galaxy, we do not detect the spectral features of these sort of massive stars. Mkn 1087 shows morphological and kinematical features that can be explained assuming that it is in interaction with two nearby galaxies: the bright KPG 103a and a dwarf ($M_B\sim-18$) star-forming companion. We argue that this dwarf companion is not a tidal object but an external galaxy because of its low metallicity [12+log(O/H) = 8.24] with respect to the one derived for Mkn 1087 [12+log(O/H) = 8.57] and its kinematics. Some of the non-stellar objects surrounding Mkn 1087 are connected by bridges of matter with the main body, host star-formation events and show similar abundances despite their different angular distances. These facts, together their kinematics, suggest that they are tidal dwarf galaxies formed from material stripped from Mkn 1087. A bright star-forming region at the south of Mkn 1087 (knot #7) does not show indications of being a tidal galaxy or the product of a merging process as suggested in previous works. We argue that Mkn 1087 and its surroundings should be considered a group of galaxies.Comment: Accepted by A&A, 21 pages, 13 figures, 8 table

Optimización multi-objetivo en las ciencias de la vida.

Para conseguir este objetivo, en lugar de intentar incorporar nuevos algoritmos directamente en el código fuente de AutoDock, se utilizó un framework orientado a la resolución de problemas de optimización con metaheurísticas. Concretamente, se usó jMetal, que es una librería de código libre basada en Java. Ya que AutoDock está implementado en C++, se desarrolló una versión en C++ de jMetal (posteriormente distribuida públicamente). De esta manera, se consiguió integrar ambas herramientas (AutoDock 4.2 y jMetal) para optimizar la energía libre de unión entre compuesto químico y receptor. Después de disponer de una amplia colección de metaheurísticas implementadas en jMetalCpp, se realizó un detallado estudio en el cual se aplicaron un conjunto de metaheurísticas para optimizar un único objetivo minimizando la energía libre de unión, el cual es el resultado de la suma de todos los términos de energía de la función objetivo de energía de AutoDock 4.2. Por lo tanto, cuatro metaheurísticas tales como dos variantes de algoritmo genético gGA (Algoritmo Genético generacional) y ssGA (Algoritmo Genético de estado estacionario), DE (Evolución Diferencial) y PSO (Optimización de Enjambres de Partículas) fueron aplicadas para resolver el problema del acoplamiento molecular. Esta fase se dividió en dos subfases en las que se usaron dos conjuntos de instancias diferentes, utilizando como receptores HIV-proteasas con cadenas laterales de aminoacidos flexibles y como ligandos inhibidores HIV-proteasas flexibles. El primer conjunto de instancias se usó para un estudio de configuración de parámetros de los algoritmos y el segundo para comparar la precisión de las conformaciones ligando-receptor obtenidas por AutoDock y AutoDock+jMetalCpp. La siguiente fase implicó aplicar una formulación multi-objetivo para resolver problemas de acoplamiento molecular dados los resultados interesantes obtenidos en estudios previos existentes en los que dos objetivos como la energía intermolecular y la energía intramolecular fueron minimizados. Por lo tanto, se comparó y analizó el rendimiento de un conjunto de metaheurísticas multi-objetivo mediante la resolución de complejos flexibles de acoplamiento molecular minimizando la energía inter- e intra-molecular. Estos algoritmos fueron: NSGA-II (Algoritmo Genético de Ordenación No dominada) y su versión de estado estacionario (ssNSGA-II), SMPSO (Optimización Multi-objetivo de Enjambres de Partículas con Modulación de Velocidad), GDE3 (Tercera versión de la Evolución Diferencial Generalizada), MOEA/D (Algoritmo Evolutivo Multi-Objetivo basado en la Decomposición) y SMS-EMOA (Optimización Multi-objetivo Evolutiva con Métrica S). Después de probar enfoques multi-objetivo ya existentes, se probó uno nuevo. En concreto, el uso del RMSD como un objetivo para encontrar soluciones similares a la de la solución de referencia. Se replicó el estudio previo usando este conjunto diferente de objetivos. Por último, se analizó de forma detallada el algoritmo que obtuvo mejores resultados en los estudios previos. En concreto, se realizó un estudio de variantes del SMPSO minimizando la energía intermolecular y el RMSD. Este estudio proporcionó algunas pistas sobre cómo nuevos algoritmos basados en SMPSO pueden ser adaptados para mejorar los resultados de acoplamiento molecular para aquellas simulaciones que involucren ligandos y receptores flexibles. Esta tesis demuestra que la inclusión de técnicas metaheurísticas de jMetalCpp en la herramienta de acoplamiento molecular AutoDock incrementa las posibilidades a los usuarios de ámbito biológico cuando resuelven el problema del acoplamiento molecular. El uso de técnicas de optimización mono-objetivo diferentes aparte de aquéllas ampliamente usadas en las comunidades de acoplamiento molecular podría dar lugar a soluciones de mayor calidad. En nuestro caso de estudio mono-objetivo, el algoritmo de evolución diferencial obtuvo mejores resultados que aquellos obtenidos por AutoDock. También se propone diferentes enfoques multi-objetivo para resolver el problema del acoplamiento molecular, tales como la decomposición de los términos de la energía de unión o el uso del RMSD como un objetivo. Finalmente, se demuestra que el SMPSO, una metaheurística de optimización multi-objetivo de enjambres de partículas, es una técnica remarcable para resolver problemas de acoplamiento molecular cuando se usa un enfoque multi-objetivo, obteniendo incluso mejores soluciones que las técnicas mono-objetivo.Las herramientas de acoplamiento molecular han llegado a ser bastante eficientes en el descubrimiento de fármacos y en el desarrollo de la investigación de la industria farmacéutica. Estas herramientas se utilizan para elucidar la interacción de una pequeña molécula (ligando) y una macro-molécula (diana) a un nivel atómico para determinar cómo el ligando interactúa con el sitio de unión de la proteína diana y las implicaciones que estas interacciones tienen en un proceso bioquímico dado. En el desarrollo computacional de las herramientas de acoplamiento molecular los investigadores de este área se han centrado en mejorar los componentes que determinan la calidad del software de acoplamiento molecular: 1) la función objetivo y 2) los algoritmos de optimización. La función objetivo de energía se encarga de proporcionar una evaluación de las conformaciones entre el ligando y la proteína calculando la energía de unión, que se mide en kcal/mol. En esta tesis, se ha usado AutoDock, ya que es una de las herramientas de acoplamiento molecular más citada y usada, y cuyos resultados son muy precisos en términos de energía y valor de RMSD (desviación de la media cuadrática). Además, se ha seleccionado la función de energía de AutoDock versión 4.2, ya que permite realizar una mayor cantidad de simulaciones realistas incluyendo flexibilidad en el ligando y en las cadenas laterales de los aminoácidos del receptor que están en el sitio de unión. Se han utilizado algoritmos de optimización para mejorar los resultados de acoplamiento molecular de AutoDock 4.2, el cual minimiza la energía libre de unión final que es la suma de todos los términos de energía de la función objetivo de energía. Dado que encontrar la solución óptima en el acoplamiento molecular es un problema de gran complejidad y la mayoría de las veces imposible, se suelen utilizar algoritmos no exactos como las metaheurísticas, para así obtener soluciones lo suficientemente buenas en un tiempo razonable

Conodonts, microfacies and palaeoenvironment during the mid-Tournaisian Event - comparison of platform and basin (lower Mississsippian, Germany and Belgium)

The globally traceable mid-Tournaisian Event (lower Carboniferous, Mississippian) was the result of glacio-eustatic sea-level fluctuations and its formation a matter of ongoing discussions. Two opposing sides postulate either a formation during a transgression or during an episode of a waxing ice sheet. Here, an attempt is made to clarify the formation mechanisms, employing conodont biostratigraphy, conodont biofacies zonation, microfacies analysis and sequence stratigraphy. A review of the existing conodont biozonation models for the lower Carboniferous visualizes the differences that are the result of varying accumulation realms, and allows the correlation between the models. Sequence stratigraphy is used to support the correlation. The review also questions the usefulness of "standard" biozonation models as they cannot be applied to conodont faunas originating from shallow-water environments. Three studies from the Rhenish Mountains (Riescheid, Gladenbach, Wettmarsen) and one from the eastern Belgian Namur-Dinant Basin (Dolhain) represent different settings along a platform-basin transect and were used to reconstruct the conditions during the mid-Tournaisian Event. The section Riescheid, that is situated within the Herzkamp Syncline in the western Rhenish Mountains exposes middle Famennian to Upper Viséan strata of the Kulm facies (basin facies). The middle Tournaisian Kahlenberg Fm consists of dark shales and a package of intercalated calciturbidites and was accumulated during the Transgressive Systems Tract (TST) and Highstand Systems Tract (HST) of Sequence 2. The retrieved very poor conodont fauna indicates the affiliation to the isosticha-Upper crenulata Zone and the Siphonodellid Biofacies that represents lower slope to basin environments. The microfacies analysis allows the reconstruction of the sedimentational conditions. They reveal the accumulation of hemipelagic calciturbidites in distal, lower slope environments. The Gladenbach section, situated in the eastern Rhenish Mountains, exposes middle Tournaisian strata. They differ from the “normal” facies due to their origin from the allochthonous Hörre Nappe. The Gladenbach Fm, equivalent to the Kahlenberg Fm and the lower part of the Hardt Fm, consists of dark, bituminous limestones and intercalated dark shales, representing many turbiditic fining upward cycles. These can be assigned to the Transgressive Systems Tract (TST) and HST of Sequence 2 and the lower part of Sequence 3. The rich conodont fauna allows the recognition of the Lower crenulata, isosticha-Upper crenulata and Lower typicus zones and the assignment to the Siphonodellid-Polygnathid Biofacies (lower slope and basin) of the Gladenbach Fm. The microfacies analysis reveals an accumulation realm in a deep basin close to the lower slope. The section Wettmarsen is situated in the Remscheid-Altena Anticline in the Rhenish Mountains and exposes middle Famennian to middle Tournaisian strata of the Kulm type facies. It contains a depositional gap between Upper Devonian and lower Carboniferous. Sequence 2 as well as the Lowstand Systems Tract (LST) and undifferentiated TST/HST of Sequence 3 can be recognized. The calciturbidite bed of the Kahlenberg Fm originated from a high rising intrabasinal swell on top of the former Devonian Balve reef complex southwest of the section. A rich conodont fauna could be retrieved from this calciturbidite bed, allowing the assignment to the isosticha-Upper crenulata Zone. An allocation to middle to upper shelf slope areas was possible, based on the gnathodid-dominated conodont fauna and the microfacies analysis. The recently cut (2010), hardly studied eastern Belgian Dolhain section is situated in the Verviers Syncline within the Vesdre-Aachen sedimentation area and exposes uppermost Famennian to Ivorian strata. The Pont d'Arcole Fm is composed of a variety of shales and limestones, representing Sequence 2 together with the pure limestone succession of the overlying Landelies Fm. Dark shales in the middle part of the Pont d’Arcole Fm represent the maximum flooding interval (mfi). Strongly increasing percentages of limestone beds above indicate the beginning of the HST. A single rich conodont fauna directly above the mfi indicates the Lower crenulata Zone. The polygnathid-pseudopolygnathid dominated fauna, as well as microfacies and sequence stratigraphy indicate deep (outer) shelf below wave base. In the studied sections from the Rhenish Mountains the middle Tournaisian Kahlenberg Fm and the Gladenbach Fm represent accumulations of deep basins or deep distal slope areas that in part were fed by calciturbidites deriving from deeper water and lower, middle and upper slope deposits. The studied section of the Pont d’Arcole Fm is a deep open-shelf succession. In summary, the results of this study support an exaggerated transgression resulting in the mid-Tournaisian Event

Discovery of First-in-Class Small Molecule Agonists of the RXFP2 Receptor as Therapeutic Candidates for Osteoporosis

Osteoporosis is a chronic bone disease characterized by decreased bone mass and increased risk of developing fractures, predominantly observed in the elderly. The pathophysiological cause of the disease is a decrease in the activity of the bone-forming cells (osteoblasts) that alters bone remodeling in favor of bone resorption, leading to a decrease in bone mass. Recent studies identified the relaxin family peptide receptor 2 (RXFP2), the G protein-coupled receptor (GPCR) for insulin-like 3 peptide (INSL3), as an attractive target expressed in osteoblast cells to increase bone formation. The goal of this dissertation is to discover and characterize small molecule agonists of RXFP2 that are stable and can be delivered orally to promote bone growth. Several low molecular weight compounds were identified as agonists of the RXFP2 receptor using a cAMP high-throughput screen of the NCATS small molecule library. An extensive structure-activity relationship campaign resulted in highly potent and efficient full RXFP2 agonists. The selectivity and specificity of these compounds for human and mouse RXFP2 was shown in counter-screens against the related relaxin receptor RXFP1 and other GPCRs. Using a series of RXFP2/RXFP1 chimeric receptors, in silico modeling and RXFP2 point mutants, we established that the compounds are allosteric agonists of the RXFP2 receptor and identified the GPCR transmembrane domains as the specific region for compound interaction. We also showed that the candidate compounds promoted mineralization in primary human osteoblasts and had low cytotoxicity in various cell types. The compound with the highest activity in vitro was selected for pharmacokinetics profiling in mice, showing oral bioavailability and bone exposure. Moreover, an efficacy study in wild-type female mice treated orally with the lead compound showed a significant increase of the vertebral trabecular number and thickness compared to vehicle treated controls. Overall, our study has successfully identified and characterized the first-in-class small molecule series of RXFP2 agonists, which may lead to the development of a new class of orally bioavailable drugs for the treatment of diseases associated with bone loss

A monitoring and threat detection system using stream processing as a virtual function for big data

The late detection of security threats causes a significant increase in the risk of irreparable damages, disabling any defense attempt. As a consequence, fast realtime threat detection is mandatory for security guarantees. In addition, Network Function Virtualization (NFV) provides new opportunities for efficient and low-cost security solutions. We propose a fast and efficient threat detection system based on stream processing and machine learning algorithms. The main contributions of this work are i) a novel monitoring threat detection system based on stream processing; ii) two datasets, first a dataset of synthetic security data containing both legitimate and malicious traffic, and the second, a week of real traffic of a telecommunications operator in Rio de Janeiro, Brazil; iii) a data pre-processing algorithm, a normalizing algorithm and an algorithm for fast feature selection based on the correlation between variables; iv) a virtualized network function in an open-source platform for providing a real-time threat detection service; v) near-optimal placement of sensors through a proposed heuristic for strategically positioning sensors in the network infrastructure, with a minimum number of sensors; and, finally, vi) a greedy algorithm that allocates on demand a sequence of virtual network functions.A detecção tardia de ameaças de segurança causa um significante aumento no risco de danos irreparáveis, impossibilitando qualquer tentativa de defesa. Como consequência, a detecção rápida de ameaças em tempo real é essencial para a administração de segurança. Além disso, A tecnologia de virtualização de funções de rede (Network Function Virtualization - NFV) oferece novas oportunidades para soluções de segurança eficazes e de baixo custo. Propomos um sistema de detecção de ameaças rápido e eficiente, baseado em algoritmos de processamento de fluxo e de aprendizado de máquina. As principais contribuições deste trabalho são: i) um novo sistema de monitoramento e detecção de ameaças baseado no processamento de fluxo; ii) dois conjuntos de dados, o primeiro ´e um conjunto de dados sintético de segurança contendo tráfego suspeito e malicioso, e o segundo corresponde a uma semana de tráfego real de um operador de telecomunicações no Rio de Janeiro, Brasil; iii) um algoritmo de pré-processamento de dados composto por um algoritmo de normalização e um algoritmo para seleção rápida de características com base na correlação entre variáveis; iv) uma função de rede virtualizada em uma plataforma de código aberto para fornecer um serviço de detecção de ameaças em tempo real; v) posicionamento quase perfeito de sensores através de uma heurística proposta para posicionamento estratégico de sensores na infraestrutura de rede, com um número mínimo de sensores; e, finalmente, vi) um algoritmo guloso que aloca sob demanda uma sequencia de funções de rede virtual