1,193 research outputs found

    The Association of Compact Groups of Galaxies with Large-scale Structures

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    We use various samples of compact groups (CGs) to examine the types of association CGs have with rich and poor clusters of galaxies at low (z~0.04) and intermediate (z~0.1) redshifts. We find that ~10-20 % of CGs are associated with rich clusters and a much larger fraction with poorer clusters or loose groups. Considering the incompleteness of catalogs of poorer systems at intermediate redshift, our result is consistent with all CGs at intermediate redshift being associated with larger-scale systems. The richness of the clusters associated with CGs significantly increases from z~0.04 to z~0.1, while their Bautz-Morgan type changes from early to late type for the same range in z. Neither trend is compatible with a selection effect in the cluster catalogs used. We find earlier morphological types of galaxies to be more frequent in CGs associated with larger-scale structures, compared to those in CGs not associated to such structures. We consider this as new evidence that CGs are part of the large-scale structure formation process and that they may play an important role in the evolution of galaxies in these structures.Comment: 5 pages, no figures, Proc. ESO Workshop "Groups of galaxies in the nearby Universe", Santiago, Chile, 5-9 Dec. 2005, ESO Astrophysics Symposia, eds. I. Saviane, V. Ivanov & J. Borissova, Springer-Verlag; very minor revision of text on 15 Mar 2006, added one referenc

    Growth, functional capacities and motivation for achievement and competitiveness in youth basketball: An interdisciplinary approach

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    The interaction of multiple influences on the path to sport success is not yet fully understood by sport scientists. In this study, we examined variation in body size, functional capacities and motivation for achievement, competitiveness and deliberate practice of youth basketball players associated with differences in biological maturity status and chronological age. Reflecting the importance of interactive effects, we examined the relationships between the psychological variables and functional capacities. Fifty-eight male basketball players aged 9.5 to 15.5 years were considered. Variables included chronological age, estimated age at PHV, stature, body mass and sitting height by anthropometry; the Work and Family Orientation and Deliberate Practice Motivation Questionnaires were also used. Finally, the Line Drill test and Yo-Yo Intermittent Recovery level 1 (Yo-Yo IR1) tests were used as functional capacities indicators for basketball. Variance components models derived from series of multilevel linear regression models revealed a significant variation by maturity status for body size, functional capacities indicators, mastery and will to excel. The influence of estimated maturity status on mastery and will to excel was independent of chronological age. Furthermore, after controlling for age, an influence of estimated maturity on competitiveness was apparent. In contrast, no relationships were observed between psychological variables and functional capacities indicators. We conclude that growth-related changes are relevant to understanding players´ motivations for achievement, competitiveness and deliberate practice. This should be of interest to those involved in the selection and development of youth basketball players

    Production of entanglement in Raman three-level systems using feedback

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    We examine the theoretical limits of the generation of entanglement in a damped coupled ion-cavity system using jump-based feedback. Using Raman transitions to produce entanglement between ground states reduces the necessary feedback bandwidth, but does not improve the overall effect of the spontaneous emission on the final entanglement. We find that the fidelity of the resulting entanglement will be limited by the asymmetries produced by vibrations in the trap, but that the concurrence remains above 0.88 for realistic ion trap sizes.Comment: 8 pages, 8 figure

    Radiative decays of light vector mesons in a quark level linear sigma model

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    We calculate the P0 to gamma gamma, V0 to P0 gamma and V0to V'0 gamma gamma decays in the framework of a U(3)xU(3) linear sigma model which includes constituent quarks. For the first two decays this approach improves results based on the anomalous Wess-Zumino term, with contributions due to SU(3) symmetry breaking and vector mixing. The phi to (omega,rho) gamma gamma decays are dominated by resonant eta' exchange . Our calculation for the later decays improves and update similar calculations in the -closely related- framework of vector meson dominance. We obtain BR(phi to rho gamma gamma)=2.5x10^{-5} and BR(phi to omega gamma gamma)=2.8x10^{-6} within the scope of the high-luminosity phi factories.Comment: 8 pages, submitted to Phys. Rev.

    Variabilidade Do Desempenho No Line-drill Test Em Adolescentes Jogadores De Basquetebol

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    Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)The practice of basketball during adolescence increases the body size and functional performance. Basketball involves short-time maximum effort for changes of direction, which use anaerobic metabolism and agility. Objective: To examine the variation in performance in the Line-drill Test in adolescent basketball players (n=59, age 9-15 years) in relation to the stage of somatic maturity (estimated age of peak growth velocity [PGV]) and the variation in body size. Methods: We considered chronological age, estimated time for the age of PGV by the maturity offset protocol, height and body mass measured by anthropometry, and performance in the Line Drill Test. Proportional allometric models were used to control the variation associated with the body size, chronological age, and maturity of inter-individual variation in the Line-drill Test. Results: We found a high negative linear relationship between performance in the Line-drill Test and chronological age (r=-0.64, 95% IC -0.77 - -0.46, p<0.01). The relationship between performance on the Line-drill Test and the time until the age of PGV proved to be non-linear, indicating slowdown in performance variation, approximately from the age of PGV and one year after the predicted PGV. The allometric models showed a negative relationship between body size and performance in the Line-drill Test. The amplitude of variance explained in the proportional allometric models ranged from 0.28 to 0.48. Negative exponents of small magnitude were observed for chronological age and the indicator of maturity being, however, significant and with reduced amplitude (-0.05 to -0.06) Conclusion: The use of allometric models to control the influence of body size can potentially help to understand the development of agility performances in adolescent basketball players. © 2016, Redprint Editora Ltda. All rights reserved.226445449PNPD/CAPES/2013, CAPES, Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorFAPESP, Fundação de Amparo à Pesquisa do Estado de São PauloCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

    Constraining the dark energy with galaxy clusters X-ray data

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    The equation of state characterizing the dark energy component is constrained by combining Chandra observations of the X-ray luminosity of galaxy clusters with independent measurements of the baryonic matter density and the latest measurements of the Hubble parameter as given by the HST key project. By assuming a spatially flat scenario driven by a "quintessence" component with an equation of state px=ωρxp_x = \omega \rho_x we place the following limits on the cosmological parameters ω\omega and Ωm\Omega_{\rm{m}}: (i) 1ω0.55-1 \leq \omega \leq -0.55 and Ωm=0.320.014+0.027\Omega_{\rm m} = 0.32^{+0.027}_{-0.014} (1σ\sigma) if the equation of state of the dark energy is restricted to the interval 1ω<0-1 \leq \omega < 0 (\emph{usual} quintessence) and (ii) ω=1.290.792+0.686\omega = -1.29^{+0.686}_{-0.792} and Ωm=0.310.034+0.037\Omega_{\rm{m}} = 0.31^{+0.037}_{-0.034} (1σ1\sigma) if ω\omega violates the null energy condition and assume values <1< -1 (\emph{extended} quintessence or ``phantom'' energy). These results are in good agreement with independent studies based on supernovae observations, large-scale structure and the anisotropies of the cosmic background radiation.Comment: 6 pages, 4 figures, LaTe

    Bianchi Type I Cosmology in Generalized Saez-Ballester Theory via Noether Gauge Symmetry

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    In this paper, we investigate the generalized Saez-Ballester scalar-tensor theory of gravity via Noether gauge symmetry (NGS) in the background of Bianchi type I cosmological spacetime. We start with the Lagrangian of our model and calculate its gauge symmetries and corresponding invariant quantities. We obtain the potential function for the scalar field in the exponential form. For all the symmetries obtained, we determine the gauge functions corresponding to each gauge symmmetry which include constant and dynamic gauge. We discuss cosmological implications of our model and show that it is compatible with the observational data.Comment: 13 pages, 2 figures, accepted for publication in 'European Physical Journal C

    Alternatives to Quintessence Model Building

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    We discuss the issue of toy model building for the dark energy component of the universe. Specifically, we consider two generic toy models recently proposed as alternatives to quintessence models, known as Cardassian expansion and the Chaplygin gas. We show that the former is enteriely equivalent to a class of quintessence models. We determine the observational constraints on the latter, coming from recent supernovae results and from the shape of the matter power spectrum. As expected, these restrict the model to a behaviour that closely matches that of a standard cosmological constant Λ\Lambda.Comment: RevTex4; 7 pages, 4 figures. v2: Improved discussion of constraints on Chaplygin gas models. Other clarifications added. Phys Rev. D (in press

    Degeneration rate of preantral follicles in the ovaries of goats

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    The degeneration rate of ovarian preantral follicles in goats, and the distribution in the follicular classes (primordial, primary or secondary) was assessed. Ovaries from adult goats were collected at a local slaughterhouse. To evaluate the morphology of the caprine preantral follicles in situ, one fragment from each ovary was fixed individually in Carnoy for 12 h, sectioned serially at a thickness of 7 μm and stained with Periodic Acid Shiff-hematoxylin. Preantral follicles were then classified according to the stage of development. Preantral follicles were classified individually either as morphologically normal; as Type 1 degenerated follicles (only the oocyte was degenerated); or as Type 2 degenerated follicles (when degeneration occurred at both oocyte and granulosa cells). The total examined was 235 primordial, 195 primary and 101 secondary follicles. The distribution of degenerated follicles as primordial, primary and secondary follicles was 8.5, 14.3 and 16.8%, respectively. When Types 1 and 2 degenerated follicles were pooled, secondary follicles were significantly more degenerated than primordial and primary follicles. When degeneration Types 1 and 2 was compared in each follicular class, a higher (P<0.05) percentage of Type 1 degeneration was observed in primordial and primary follicles. Conversely, secondary follicles were significantly more affected by Type 2 degeneration. When the follicular classes were taken together, a significantly higher percentage of Type 1 degenerated preantral follicles was observed when compared with Type 2 degenerated follicles (P<0.05). In conclusion, a low percentage of degenerated preantral follicles was observed and secondary follicles were more affected by degeneration than primordial follicles. Thus, primordial follicles constitute a large and potentially valuable source of oocytes for reproductive programs after in vitro growth and maturation
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