14,790 research outputs found

    The Role of Personality in Predicting Drug and Alcohol Use Among Sexual Minorities

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    Research consistently demonstrates that sexual minority status is associated with increased risk of problematic substance use. Existing literature in this area has focused on group-specific minority stress factors (e.g., victimization and internalized heterosexism). However, no known research has tested the incremental validity of personality traits as predictors of substance use beyond identified group-specific risk factors. A sample of 704 sexual minority adults was recruited nationally from lesbian, gay, bisexual, transgender, queer, and questioning community organizations and social networking Web sites and asked to complete an online survey containing measures of personality, sexual minority stress, and substance use. Hierarchical regression models were constructed to test the incremental predictive validity of five-factor model personality traits over and above known sexual minority risk factors. Consistent with hypotheses, extraversion and conscientiousness were associated with drug and alcohol use after accounting for minority stress factors, and all factors except agreeableness were associated with substance use at the bivariate level of analysis. Future research should seek to better understand the role of normal personality structures and processes conferring risk for substance use among sexual minorities

    A Universal Temperature Profile for Galaxy Clusters

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    We investigate the predicted present-day temperature profiles of the hot, X-ray emitting gas in galaxy clusters for two cosmological models - a current best-guess LCDM model and standard cold dark matter (SCDM). Our numerically-simulated "catalogs" of clusters are derived from high-resolution (15/h kpc) simulations which make use of a sophisticated, Eulerian-based, Adaptive Mesh-Refinement (AMR) code that faithfully captures the shocks which are essential for correctly modelling cluster temperatures. We show that the temperature structure on Mpc-scales is highly complex and non-isothermal. However, the temperature profiles of the simulated LCDM and SCDM clusters are remarkably similar and drop-off as T+AFwpropto(1+r/ax)+AFwdeltaT +AFw-propto (1+-r/a_x)^{-+AFw-delta} where ax+AFwsimrvir/1.5a_x +AFw-sim r_{vir}/1.5 and +AFwdelta+AFwsim1.6+AFw-delta +AFw-sim 1.6. This decrease is in good agreement with the observational results of Markevitch et al.(1998) but diverges, primarily in the innermost regions, from their fit which assumes a polytropic equation of state. Our result is also in good agreement with a recent sample of clusters observed by BeppoSAX though there is some indication of missing physics at small radii (r<0.2rvirr<0.2 r_{vir}). We discuss the interpretation of our results and make predictions for new x-ray observations that will extend to larger radii than previously possible. Finally, we show that, for r>0.2rvirr>0.2 r_{vir}, our universal temperature profile is consistent with our most recent simulations which include both radiative cooling and supernovae feedback.Comment: 8 pages, 6 figures, accepted for publication in ApJ, full-page version of Fig. 2 at http://www.cita.utoronto.ca/+AH4-cloken/PAPERS/UTP/f2.ep

    China's Ongoing Agricultural Modernization: Challenges Remain After 30 Years of Reform

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    Thirty years ago, China began implementing a series of reforms to improve efficiency in agricultural production. These, and subsequent, reforms reshaped China’s position in the world economy. China’s rapid economic development and transformation from a planned to a market-oriented economy, however, has reached a stage where further efficiency gains in agricultural production will likely hinge on the development of modern market-supporting institutions. The development of market-supporting institutions in China will bring about long-term and sustainable benefits to producers and consumers in China and the global agricultural economy. This report provides an overview of current issues in China’s agricultural development, policy responses to these issues, and the effects of these policies on China’s growing role in international markets.China, economic reform, economic development, agricultural production, agricultural trade, Agricultural and Food Policy, International Relations/Trade, Production Economics,

    Composite Payload Fairing Structural Architecture Assessment and Selection

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    This paper provides a summary of the structural architecture assessments conducted and a recommendation for an affordable high performance composite structural concept to use on the next generation heavy-lift launch vehicle, the Space Launch System (SLS). The Structural Concepts Element of the Advanced Composites Technology (ACT) project and its follow on the Lightweight Spacecraft Structures and Materials (LSSM) project was tasked with evaluating a number of composite construction technologies for specific Ares V components: the Payload Shroud, the Interstage, and the Core Stage Intertank. Team studies strived to address the structural challenges, risks and needs for each of these vehicle components. Leveraging off of this work, the subsequent Composites for Exploration (CoEx) effort is focused on providing a composite structural concept to support the Payload Fairing for SLS. This paper documents the evaluation and down selection of composite construction technologies and evolution to the SLS Payload Fairing. Development of the evaluation criteria (also referred to as Figures of Merit or FOMs), their relative importance, and association to vehicle requirements are presented. A summary of the evaluation results, and a recommendation of the composite concept to baseline in the Composites for Exploration (CoEx) project is presented. The recommendation for the SLS Fairing is a Honeycomb Sandwich architecture based primarily on affordability and performance with two promising alternatives, Hat stiffened and Fiber Reinforced Foam (FRF) identified for eventual program block upgrade

    A Search for Jovian Planets around Hot White Dwarfs

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    Current searches for extrasolar planets have concentrated on observing the reflex Doppler shift of solar-type stars. Little is known, however, about planetary systems around non-solar-type stars. We suggest a new method to extend planetary searches to hot white dwarfs. Near a hot white dwarf, the atmosphere of a Jovian planet will be photoionized and emit hydrogen recombination lines, which may be detected by high- dispersion spectroscopic observations. Multi-epoch monitoring can be used to distinguish between non-LTE stellar emission and planetary emission, and to establish the orbital parameters of the detected planets. In the future, high-precision astrometric measurements of the hot white dwarf will allow the masses of the detected planets to be determined. Searches for Jovian planets around hot white dwarfs will provide invaluable new insight on the development of planetary systems around stars more massive than the Sun and on how stellar evolution affects these systems. We present high-dispersion spectroscopic observations of the white dwarf Feige 34 to demonstrate the complexity and feasibility of the search method.Comment: 10 pages, 2 figures, accepted for publication in the ApJ Letter

    The X-ray surface brightness distribution from diffuse gas

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    We use simulations to predict the X-ray surface brightness distribution arising from hot, cosmologically distributed diffuse gas. The distribution is computed for two bands: 0.5-2 keV and 0.1-0.4 keV, using a cosmological-constant dominated cosmology that fits many other observations. We examine a number of numerical issues such as resolution, simulation volume and pixel size and show that the predicted mean background is sensitive to resolution such that higher resolution systematically increases the mean predicted background. Although this means that we can compute only lower bounds to the predicted level, these bounds are already quite restrictive. Since the observed extra-galactic X-ray background is mostly accounted for by compact sources, the amount of the observed background attributable to diffuse gas is tightly constrained. We show that without physical processes in addition to those included in the simulations (such as radiative cooling or non-gravitational heating), both bands exceed observational limits. In order to examine the effect of non-gravitational heating we explore a simple modeling of energy injection and show that substantial amounts of heating are required (i.e. 5 keV per particle when averaged over all baryons). Finally, we also compute the distribution of surface brightness on the sky and show that it has a well-resolved characteristic shape. This shape is substantially modified by non-gravitational heating and can be used as a probe of such energy injection.Comment: 11 pages, 11 figures, submitted to Ap

    Autosensitization to DNA

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