40,910 research outputs found

    A\u27s from Zzzz\u27s? The Causal Effect of School Start Time on the Academic Achievement of Adolescents

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    Recent sleep research finds that many adolescents are sleep-deprived because of both early school start times and changing sleep patterns during the teen years. This study identifies the causal effect of school start time on academic achievement by using two policy changes in the daily schedule at the US Air Force Academy along with the randomized placement of freshman students to courses and instructors. Results show that starting the school day 50 minutes later has a significant positive effect on student achievement, which is roughly equivalent to raising teacher quality by one standard deviation. (JEL I23, J13

    Development of optical modulators for measurements of solar magnetic fields

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    The measurement of polarized light allows solar astronomers to infer the magnetic field on the Sun. The accuracy of these measurements is dependent on the stable retardation characteristics of the polarization modulators used to minimize the atmospheric effects seen in ground-based observations. This report describes the work by the Space Science Laboratory at Marshall Space Flight Center to improve two types of polarization modulators. As a result, the timing characteristics for both electrooptic crystals (KD*Ps) and liquid crystal devices (LCDs) have been studied and will be used to enhance the capabilities of the MSFC Vector Magnetograph

    Discrete mechanics and variational integrators

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    This paper gives a review of integration algorithms for finite dimensional mechanical systems that are based on discrete variational principles. The variational technique gives a unified treatment of many symplectic schemes, including those of higher order, as well as a natural treatment of the discrete Noether theorem. The approach also allows us to include forces, dissipation and constraints in a natural way. Amongst the many specific schemes treated as examples, the Verlet, SHAKE, RATTLE, Newmark, and the symplectic partitioned Runge–Kutta schemes are presented

    Increasing EHR Use for Quality Improvement in Community Health Centers: The Role of Networks

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    Describes how five community health center networks helped implement electronic health records to improve chronic and preventive care, as well as the obstacles they faced, including limited software capabilities, funding, and ability to share resources

    Internal protein dynamics shifts the distance to the mechanical transition state

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    Mechanical unfolding of polyproteins by force spectroscopy provides valuable insight into their free energy landscapes. Most experiments of the unfolding process have been fit to two-state and/or one dimensional models, with the details of the protein and its dynamics often subsumed into a zero-force unfolding rate and a distance x(u)(1D) to the transition state. We consider the entire phase space of a model protein under a constant force, and show that x(u)(1D) contains a sizeable contribution from exploring the full multidimensional energy landscape. This effect is greater for proteins with many degrees of freedom that are affected by force; and surprisingly, we predict that externally attached flexible linkers also contribute to the measured unfolding characteristics

    What makes a good employer?

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    Profiling Consumer Trend-setters in the Canadian Healthy-foods Market

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    The agri-food industry faces new challenges as consumer demand for new, healthier foods increases. Media headlines frequently mention health benefits from certain foods and food components, and consumers are more health conscious because they are aging. They realize their food choices can reduce their risk of developing chronic illnesses such as cancer and heart disease. The competitive advantages for firms who are the first to bring their food innovations to market will depend in part on the efficacy of their marketing strategies. Firms that can identify and target those consumers who are most interested in trying new foods with enhanced functional health properties will likely be the most successful. This paper identifies attitudinal and sociodemographic characteristics that influence a consumer’s desire to be among the first to try innovative functional foods.Consumer/Household Economics, Health Economics and Policy, Marketing,

    E_11 and M Theory

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    We argue that eleven dimensional supergravity can be described by a non-linear realisation based on the group E_{11}. This requires a formulation of eleven dimensional supergravity in which the gravitational degrees of freedom are described by two fields which are related by duality. We show the existence of such a description of gravity.Comment: 21 pages, some typos corrected and two references adde
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