Shapes of clusters and groups of galaxies: Comparison of model predictions with observations

We study the properties of the 3-dimensional and projected shapes of haloes using high resolution numerical simulations and observational data where the latter comes from the 2PIGG (Eke et al. 2004) and SDSS-DR3GC group catalogues (Merchan & Zandivarez 2005). We investigate the dependence of halo shape on characteristics such as mass and number of members. In the 3-dimensional case, we find a significant correlation between the mass and halo shape; massive systems are more prolate than small haloes. We detect a source of strong systematics in estimates of the triaxiality of a halo, which is found to be a strong function of the number of members; LCDM haloes usually characterised by triaxial shapes, slightly bent toward prolate forms, appear more oblate when taking only a small subset of the halo particles. The ellipticities of observed 2PIGG and SDSS-DR3GC groups are found to be strongly dependent on the number of group members, so that poor groups appear more elongated than rich ones. However, this is again an artifact caused by poor statistics and not an intrinsic property of the galaxy groups, nor an effect from observational biases. We interpret these results with the aid of a GALFORM mock 2PIGG catalogue. When comparing the group ellipticities in mock and real catalogues, we find an excellent agreement between the trends of shapes with number of group members. When carefully taking into account the effects of low number statistics, we find that more massive groups are consistent with more elongated shapes. Finally, our studies find no significant correlations between the shape of observed 2PIGG or SDSS-DR3GC groups with the properties of galaxy members such as colour or spectral type index.Comment: 9 pages, 10 figures, submitted to MNRA

La colección herpetológica de Bolivia depositada en la Estación Biológica de Doñana

The collection consists of 822 specimens, of which 529 are amphibians, all of them anurans (5 families, 17 genera and 51 species) and 293 specimens are reptiles (10 families, 28 genera and 49 species). The collection has around 25% of the amphibians species known to occur in Bolivia and about 19% of the reptile species. They come from 55 localities of the Bolivian Departments of Beni, Chuquisaca, Cochabamba, La Paz, Potosí and Santa Cruz and represent the following bioregions: Puna, Chaco, Chiquitanian Forest, Wet Savannas, Ceja de Montaña, Yungas, Interandean Dry Valleys and Humid Lowland Forest. The specimens of Scinax chiquitanus and Phrynopus kempffi are paratypes. The record of Pleurodema borelli is the first for the Santa Cruz Department and second for Bolivia. Liolaemus dorbignyi also constitutes the second report for the country and Tropidurus melanopleurus is cited for the first time for the Beni Department.La colección se compone de 822 ejemplares, 529 anfibios y 293 reptiles. Los anfibios son todos anuros, pertenecientes a 51 especies de 17 géneros y cinco familias. Los reptiles estan representados por 49 especies, incluidas en 28 géneros de 10 familias. Los ejemplares provienen de 55 localidades repartidas en los Departamentos bolivianos de Beni, Chuquisaca, Cochabamba, La Paz, Potosí y Santa Cruz, y representan las siguientes bioregiones: Puna, Chaco, Bosque Chiquitano, Sabanas Húmedas, Ceja de Montaña, Yungas, Valles Secos Interandinos y Bosque Húmedo de Llanura. Los ejemplares de Scinax chiquitanus y Phrynopus kempffi son paratipos. Pleurodema borelli es citada por primera vez para el Departamento de Santa Cruz y por segunda vez para Bolivia; también el registro de Liolaemus dorbignyi constituye el segundo para el país y el de Tropidurus melanopleurus el primero para el Departamento Beni

Quasar-galaxy and AGN-galaxy cross-correlations

We compute quasar-galaxy and AGN-galaxy cross-correlation functions for samples taken from the \cite{VCV98} catalog of quasars and active galaxies, using tracer galaxies taken from the Edinburgh/Durham Southern Catalog. The sample of active galaxy targets shows positive correlation at projected separations $r_p < 6 h^{-1} Mpc$ consistent with the usual power-law. On the other hand, we do not find a statistically significant positive quasar-galaxy correlation signal except in the range $3 h^{-1} Mpc < r_p < 6 h^{-1} Mpc$ where we find similar AGN-galaxy and quasar-galaxy correlation amplitudes. At separations $r_p<3 h^{-1} Mpc$ a strong decline of quasar-galaxy correlations is observed, suggesting a significant local influence of quasars in galaxy formation. In an attempt to reproduce the observed cross-correlation between quasars and galaxies, we have performed CDM cosmological hydrodynamical simulations and tested the viability of a scenario based on the model developed by \cite{silkrees98}. In this scheme a fraction of the energy released by quasars is considered to be transferred into the baryonic component of the intergalactic medium in the form of winds. The results of the simulations suggest that the shape of the observed quasar-galaxy cross-correlation function could be understood in a scenario where a substantial amount of energy is transferred to the medium at the redshift of maximum quasar activity.Comment: 11 pages, 9 figures. Accepted for publication in Ap

Correlation Function of Galaxy Groups

We use the Updated Zwicky Catalog of galaxies (Falco et al. 1999) to generate a catalog of groups, by means of a friend-of-friend algorithm. The correlation length of the total sample is well fitted with a power law $\xi(r)=(r/r_0)^\gamma$ with parameters $r_0=9.0 \pm 0.4 h^{-1}Mpc$ and $\gamma = -1.67 \pm 0.09$ for values of $r<70 h^{-1} Mpc$. Three subsamples defined by the range of group virial masses ${\cal M}$ were used to have their clustering properties examined throughout the autocorrelation function. We find an increase of the amplitude of the correlation function according to the group masses which extends the results of the $r_0-d_c$ relation for galaxy systems at small $d_c$. For completeness we have also analyzed a sample of groups obtained from the Southern Sky Redshift Survey (da Costa et al.1998) in the range of virial masses $5\times10^{12}M_{\odot}<{\cal M}<4\times10^{14}M_{\odot}$ to compare the results with those obtained from GUZC.Comment: 9 figures, accepted for publication in Ap

Assessment of the potential energy hypersurfaces in thymine within multiconfigurational theory: CASSCF vs. CASPT2

The present study provides new insights into the topography of the potential energy hypersurfaces (PEHs) of the thymine nucleobase in order to rationalize its main ultrafast photochemical decay paths by employing two methodologies based on the complete active space self-consistent field (CASSCF) and the complete active space second-order perturbation theory (CASPT2) methods: (i) CASSCF optimized structures and energies corrected with the CASPT2 method at the CASSCF geometries and (ii) CASPT2 optimized geometries and energies. A direct comparison between these strategies is drawn, yielding qualitatively similar results within a static framework. A number of analyses are performed to assess the accuracy of these different computational strategies under study based on a variety of numerical thresholds and optimization methods. Several basis sets and active spaces have also been calibrated to understand to what extent they can influence the resulting geometries and subsequent interpretation of the photochemical decay channels. The study shows small discrepancies between CASSCF and CASPT2 PEHs, displaying a shallow planar or twisted 1(ππ*) minimum, respectively, and thus featuring a qualitatively similar scenario for supporting the ultrafast bi-exponential deactivation registered in thymine upon UV-light exposure. A deeper knowledge of the PEHs at different levels of theory provides useful insight into its correct characterization and subsequent interpretation of the experimental observations. The discrepancies displayed by the different methods studied here are then discussed and framed within their potential consequences in on-the-fly non-adiabatic molecular dynamics simulations, where qualitatively diverse outcomes are expected

FACTORES PSICOLÓGICOS QUE INCIDEN EN LOS JUGADORES PROFESIONALES DE SAMPAS BOYACÁ EN COMPETENCIA

Los jugadores del club deportivo Sampas en la ciudad de Tunja- Boyacá, son jugadores profesionales de Fútbol sala. Durante los torneos disputados se obtenían mínimos resultados a pesar del trabajo realizado en los entrenamientos, con relación a la preparación física. Esta situación es susceptible de investigar para identificar otros elementos que, influyen en el rendimiento deportivo como los psicológicos, a través de un estudio cuantitativo, de tipo no experimental descriptivo, con la aplicación del cuestionario de características psicológicas relacionado con el rendimiento deportivo (CPRD), el cual describe los factores psicológicos que inciden en los jugadores de futbol sala objeto de estudio en competencia, y es el resultado de un proceso de investigación que puntualiza, el estado psicológico en el cual se encuentran estos jugadores profesionales antes de una competencia, la muestra fueron 12 jugadores profesionales con edades entre los 19 y 31 años boyacenses, realizada antes de un encuentro deportivo clasificatorio a cuartos de final de la liga argos Fútbol sala, y donde se logra establecer que el (CPRD) fue la técnica adecuada para realizar un análisis de los factores psicológicos que inciden en los jugadores en competencias, se encontró que los factores psicológicos que inciden en competencias en el equipo de Sampas en orden de importancia son; control de estrés, influencia, cohesión de equipo, motivación y habilidad mental.se logro al final del estudio determinar que el estrés es el factor que presenta mayor incidencia al momento de competir con un percentil de 80 según la tabla de baremos y además que la motivación y la habilidad mental los factores que requieren menos intervención por parte del especialista y que la estrategia de intervención psicofisiológica fue la adecuada para fortalecer el grupo en competencia

Galaxy groups in the 2dF redshift survey: Galaxy Spectral Type Segregation in Groups

The behaviour of the relative fraction of galaxies with different spectral types in groups is analysed as a function of projected local galaxy density and the group-centric distance. The group sample was taken from the 2dF Group Galaxy Calatogue constructed by Merch\'an & Zandivarez. Our group sample was constrained to have a homogeneous virial mass distribution with redshift. Galaxies belonging to this group sample were selected in order to minimize possible biases such as preferential selection of high luminosity objects. We find a clear distinction between high virial mass groups (M_V\gsim 10^{13.5} M_{\odot}) and the less massive ones. While the massive groups show a significant dependence of the relative fraction of low star formation galaxies on local galaxy density and group-centric radius,groups with lower masses show no significant trends. We also cross-correlate our group subsample with the previously identified clusters finding that this sample shows a very similar behaviour as observed in the high virial mass group subsample.Comment: 3 figures replaced, accepted for publication in MNRA