9,274 research outputs found

    Personality Profiles of Iditasport Ultra-marathon Participants

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    Each February, competitors convene in Big Lake, Alaska, to participate in the “Iditasport Human Powered Ultra-Marathon”. Who would attempt this challenging race? Personality might be one factor predicting participation. Iditasport represents a unique athletic event with a distinctive social and psychological climate that might be reflected in the personalities of the participants in many ways. This study was designed to identify the personality profile of Iditasport athletes when compared to normative populations and to explore differences between athletes competing in different race divisions

    Carbon and oxygen in metal-poor halo stars

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    Carbon and oxygen are key tracers of the Galactic chemical evolution; in particular, a reported upturn in [C/O] towards decreasing [O/H] in metal-poor halo stars could be a signature of nucleosynthesis by massive Population III stars. We reanalyse carbon, oxygen, and iron abundances in thirty-nine metal-poor turn-off stars. For the first time, we take into account three-dimensional (3D) hydrodynamic effects together with departures from local thermodynamic equilibrium (LTE) when determining both the stellar parameters and the elemental abundances, by deriving effective temperatures from 3D non-LTE HÎČ\beta profiles, surface gravities from Gaia parallaxes, iron abundances from 3D LTE Feii equivalent widths, and carbon and oxygen abundances from 3D non-LTE Ci and Oi equivalent widths. We find that [C/Fe] stays flat with [Fe/H], whereas [O/Fe] increases linearly up to 0.750.75 dex with decreasing [Fe/H] down to −3.0-3.0 dex. As such [C/O] monotonically decreases towards decreasing [O/H], in contrast to previous findings, mainly by virtue of less severe non-LTE effects for Oi at low [Fe/H] with our improved calculations.Comment: 5 pages, 2 figures; published in A&A Letter

    Effective temperature determinations of late-type stars based on 3D non-LTE Balmer line formation

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    Hydrogen Balmer lines are commonly used as spectroscopic effective temperature diagnostics of late-type stars. However, the absolute accuracy of classical methods that are based on one-dimensional (1D) hydrostatic model atmospheres and local thermodynamic equilibrium (LTE) is still unclear. To investigate this, we carry out 3D non-LTE calculations for the Balmer lines, performed, for the first time, over an extensive grid of 3D hydrodynamic STAGGER model atmospheres. For Hα\alpha, HÎČ\beta, and HÎł\gamma, we find significant 1D non-LTE versus 3D non-LTE differences (3D effects): the outer wings tend to be stronger in 3D models, particularly for HÎł\gamma, while the inner wings can be weaker in 3D models, particularly for Hα\alpha. For Hα\alpha, we also find significant 3D LTE versus 3D non-LTE differences (non-LTE effects): in warmer stars (Teff≈6500T_{\text{eff}}\approx6500K) the inner wings tend to be weaker in non-LTE models, while at lower effective temperatures (Teff≈4500T_{\text{eff}}\approx4500K) the inner wings can be stronger in non-LTE models; the non-LTE effects are more severe at lower metallicities. We test our 3D non-LTE models against observations of well-studied benchmark stars. For the Sun, we infer concordant effective temperatures from Hα\alpha, HÎČ\beta, and HÎł\gamma; however the value is too low by around 50K which could signal residual modelling shortcomings. For other benchmark stars, our 3D non-LTE models generally reproduce the effective temperatures to within 1σ1\sigma uncertainties. For Hα\alpha, the absolute 3D effects and non-LTE effects can separately reach around 100K, in terms of inferred effective temperatures. For metal-poor turn-off stars, 1D LTE models of Hα\alpha can underestimate effective temperatures by around 150K. Our 3D non-LTE model spectra are publicly available, and can be used for more reliable spectroscopic effective temperature determinations.Comment: 19 pages, 10 figures, abstract abridged; accepted for publication in Astronomy & Astrophysic

    Cellular automata on regular rooted trees

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    We study cellular automata on regular rooted trees. This includes the characterization of sofic tree shifts in terms of unrestricted Rabin automata and the decidability of the surjectivity problem for cellular automata between sofic tree shifts

    Moral reasoning and homosexuality: the acceptability of arguments about lesbian and gay issues

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    In the political arena, lesbian and gay issues have typically been contested on grounds of human rights, but with variable success. Using a moral developmental framework, the purpose of this study was to explore preferences for different types of moral arguments when thinking about moral dilemmas around lesbian and gay issues. The analysis presented here comprised data collected from 545 students at UK universities, who completed a questionnaire, part of which comprised a moral dilemma task. Findings of the study showed that respondents do not apply moral reasoning consistently, and do not (clearly) favour human rights reasoning when thinking about lesbian and gay issues. Respondents tended to favour reasoning supporting existing social structures and frameworks, therefore this study highlights the importance of structural change in effecting widespread attitude change in relation to lesbian and gay rights issues. The implications of the findings for moral education are also discussed.</p

    Coherence in scale-free networks of chaotic maps

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    We study fully synchronized states in scale-free networks of chaotic logistic maps as a function of both dynamical and topological parameters. Three different network topologies are considered: (i) random scale-free topology, (ii) deterministic pseudo-fractal scale-free network, and (iii) Apollonian network. For the random scale-free topology we find a coupling strength threshold beyond which full synchronization is attained. This threshold scales as k−Όk^{-\mu}, where kk is the outgoing connectivity and ÎŒ\mu depends on the local nonlinearity. For deterministic scale-free networks coherence is observed only when the coupling strength is proportional to the neighbor connectivity. We show that the transition to coherence is of first-order and study the role of the most connected nodes in the collective dynamics of oscillators in scale-free networks.Comment: 9 pages, 8 figure
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