5,865 research outputs found

    ECONOMIC INSIGHTS INTO THE SITING PROBLEM: AN APPLICATION OF THE EXPECTED UTILITY MODEL

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    Despite the generally recognized need for facilities such as power plants, landfills, prisons, and medical laboratories, finding host sites has become extremely difficult. This study uses the expected utility (EU) model to explain individiuals' preferences in the hypothetical case of siting a municipal solid waste composting facility. The three principal factors which EU theory prescribes would affect the decision process- benefits of the proposed facility, losses from the facility, and the (perceived) probability of various scenarios occurring- embodied by the variables in a multinomial logit model explain a substantial amount of the variation in siting decisions.Public Economics,

    Linking Ultracold Polar Molecules

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    We predict that pairs of polar molecules can be weakly bound together in an ultracold environment, provided that a dc electric field is present. The field that links the molecules together also strongly influences the basic properties of the resulting dimer, such as its binding energy and predissociation lifetime. Because of their long-range character these dimers will be useful in disentangling cold collision dynamics of polar molecules. As an example, we estimate the microwave photoassociation yield for OH-OH cold collisions.Comment: 4 pages 2 figure

    Goals and Distractions: Explanations of Early Attrition from Traditional University Freshmen

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    This grounded theory study was designed to investigate the factors that influenced 20 traditional university freshmen to withdraw prior to the end of their first year at two Midwestern universities. A two-hour audio- taped interview was conducted with each of the participants, and the grounded theory method was utilized to analyze the interview data. Eighteen of the twenty participants had strong high school GPAs and ACT scores, and would not have been identified as being at-risk for attrition. The grounded theory that emerged from the participants\u27 data indicated that an absence of clear educational goals, as well as individual and institutional distractions, interacted to contribute to the participants\u27 withdrawal from their universities

    Fidelity for imperfect postselection

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    We describe a simple measure of fidelity for mixed state postselecting devices. The measure is most appropriate for postselection where the task performed by the output is only effected by a specific state.Comment: 8 Pages, 8 Figure

    Dynamic structure elucidation of chemical reactivity by laser pulses and X-ray probes

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    Visualising chemical reactions by X-ray methods is a tantalising prospect. New light sources provide the prospect for studying atomic, electronic and energy transfers accompanying chemical change by X-ray spectroscopy and inelastic scattering. Here we assess how this adventure can illuminate inorganic and catalytic chemistry. In particular X-ray inelastic scattering provides a means of exploiting X-ray free electron lasers, as a parallel to laser Raman spectroscopy

    An Alternative Path for the Evolution of Biological Nitrogen Fixation

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    Nitrogenase catalyzed nitrogen fixation is the process by which life converts dinitrogen gas into fixed nitrogen in the form of bioavailable ammonia. The most common form of nitrogenase today requires a complex metal cluster containing molybdenum (Mo), although alternative forms exist which contain vanadium (V) or only iron (Fe). It has been suggested that Mo-independent forms of nitrogenase (V and Fe) were responsible for N2 fixation on early Earth because oceans were Mo-depleted and Fe-rich. Phylogenetic- and structure-based examinations of multiple nitrogenase proteins suggest that such an evolutionary path is unlikely. Rather, our results indicate an evolutionary path whereby Mo-dependent nitrogenase emerged within the methanogenic archaea and then gave rise to the alternative forms suggesting that they arose later, perhaps in response to local Mo limitation. Structural inferences of nitrogenase proteins and related paralogs suggest that the ancestor of all nitrogenases had an open cavity capable of binding metal clusters which conferred reactivity. The evolution of the nitrogenase ancestor and its associated bound metal cluster was controlled by the availability of fixed nitrogen in combination with local environmental factors that influenced metal availability until a point in Earth’s geologic history where the most desirable metal, Mo, became sufficiently bioavailable to bring about and refine the solution (Mo-nitrogenase) we see perpetuated in extant biology

    Local light-ray rotation

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    We present a sheet structure that rotates the local ray direction through an arbitrary angle around the sheet normal. The sheet structure consists of two parallel Dove-prism sheets, each of which flips one component of the local direction of transmitted light rays. Together, the two sheets rotate transmitted light rays around the sheet normal. We show that the direction under which a point light source is seen is given by a Mobius transform. We illustrate some of the properties with movies calculated by ray-tracing software.Comment: 9 pages, 6 figure

    Effects of Brown Midrib Corn Silage Hybrids with or without Kernel Processing at Harvest on Nutrient Metabolism in Beef Steers

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    A 2 × 3 factorial digestion study evaluated three corn silage hybrids and kernel processing for finishing steers. The three hybrids included a control corn silage, a brown midrib, and a brown midrib with a softer endosperm. Both brown midrib hybrids had greater fiber digestibility than the traditional control corn silage hybrid. No differences were observed between brown midrib hybrids for all other nutrients. Cattle fed brown midrib hybrids had a lower average ruminal pH compared to the control suggesting more fermentation, but no differences in volatile fatty acid concentration or proportions. Kernel processing had no effect on apparent total tract nutrient digestibility for any nutrients measured in this study. Kernel processing did not impact any ruminal characteristics or metabolism by beef steers. In finishing diets including elevated levels of corn silage, brown midrib corn silage hybrids allow for improved fiber digestibility and more energy available to the animal for improved growth performance over cattle fed control corn silages. Kernel processing did not appear to affect any ruminal fermentation and digestibility parameters, despite an observed improvement in feed efficiency in a similar finishing trial

    Objective cough frequency in Idiopathic Pulmonary Fibrosis

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    Background: Cough is a common presenting symptom in patients with Idiopathic Pulmonary Fibrosis (IPF). This study measured cough rates in IPF patients and investigated the association between cough and measures of health related quality of life and subjective cough assessments. In addition, IPF cough rates were related to measures of physiological disease severity and compared to cough rates in health and other respiratory conditions.Methods: Nineteen IPF patients, mean age 70.8 years ± 8.6, five female (26.3%) were studied. Subjects performed full pulmonary function testing, 24 hour ambulatory cough recordings, completed a cough related quality of life questionnaire (Leicester Cough Questionnaire) and subjectively scored cough severity with a visual analogue scale. Ambulatory cough recordings were manually counted and reported as number of coughs per hour.Results: The 24hr cough rates were high (median 9.4, range 1.5-39.4), with day time rates much higher than night time (median 14.6, range 1.9-56.6 compared to 1.9, range 0-19.2, p = 0.003). Strong correlations were found between objective cough frequency and both the VAS (day r = 0.80, p &lt; 0.001, night r = 0.71, p = 0.001) and LCQ (r = -0.80, p &lt; 0.001), but not with measures of pulmonary function. Cough rates in IPF were higher than healthy subjects (p &lt; 0.001) and asthma patients (p &lt; 0.001) but similar to patients with chronic cough (p = 0.33).Conclusions: This study confirms objectively that cough is a major, very distressing and disabling symptom in IPF patients. The strong correlations between objective cough counts and cough related quality of life measures suggest that in IPF patient's, perception of cough frequency is very accurate.</p
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