15,566 research outputs found

    Silver-base ternary alloy proves superior for slip ring lead wires

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    Slip ring lead wires composed of ternary alloys of silver, have high electrical conductivity, a tensile strength of at least 30,000 psi, high ductility, and are solderable and weldable. An unexpected advantage of these alloys is their resistance to discoloration on heating in air

    Simple numerical method for predicting steady compressible flows

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    A numerical method for solving the isenthalpic form of the governing equations for compressible viscous and inviscid flows was developed. The method was based on the concept of flux vector splitting in its implicit form. The method was tested on several demanding inviscid and viscous configurations. Two different forms of the implicit operator were investigated. The time marching to steady state was accelerated by the implementation of the multigrid procedure. Its various forms very effectively increased the rate of convergence of the present scheme. High quality steady state results were obtained in most of the test cases; these required only short computational times due to the relative efficiency of the basic method

    Esscher transform and the duality principle for multidimensional semimartingales

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    The duality principle in option pricing aims at simplifying valuation problems that depend on several variables by associating them to the corresponding dual option pricing problem. Here, we analyze the duality principle for options that depend on several assets. The asset price processes are driven by general semimartingales, and the dual measures are constructed via an Esscher transformation. As an application, we can relate swap and quanto options to standard call and put options. Explicit calculations for jump models are also provided.Comment: Published in at http://dx.doi.org/10.1214/09-AAP600 the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Family Supportive Supervision Around the Globe

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    Family-supportive supervision (FSS) refers to the degree to which employees perceive their immediate supervisors as exhibiting attitudes and behaviors that are supportive of their family role demands (Hammer, Kossek, Zimmerman, & Daniels, 2007; Kossek, Pichler, Bodner & Hammer, 2011: Thomas & Ganster, 1995). A growing body of research suggests that leaders\u27 and supervisors\u27 social support of employees\u27 needs to jointly carry out work and family demands is important for general health and job attitudes, such as satisfaction, work-family conflict, commitment, and intention to turn over (Hammer, Kossek, Anger, Bodner, & Zimmerman, 2009; Kossek et al., 2011). Thus, employee perceptions of FSS are critical to individual well-being and productivity (Hammer, Kossek, Yragui, Bodner, & Hansen, 2009). [excerpt

    COVID-19 and the difficulty of inferring epidemiological parameters from clinical data

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    Knowing the infection fatality ratio (IFR) is of crucial importance for evidence-based epidemic management: for immediate planning; for balancing the life years saved against the life years lost due to the consequences of management; and for evaluating the ethical issues associated with the tacit willingness to pay substantially more for life years lost to the epidemic, than for those to other diseases. Against this background Verity et al. (2020, Lancet Infections Diseases) have rapidly assembled case data and used statistical modelling to infer the IFR for COVID-19. We have attempted an in-depth statistical review of their approach, to identify to what extent the data are sufficiently informative about the IFR to play a greater role than the modelling assumptions, and have tried to identify those assumptions that appear to play a key role. Given the difficulties with other data sources, we provide a crude alternative analysis based on the Diamond Princess Cruise ship data and case data from China, and argue that, given the data problems, modelling of clinical data to obtain the IFR can only be a stop-gap measure. What is needed is near direct measurement of epidemic size by PCR and/or antibody testing of random samples of the at risk population.Comment: Version accepted by the Lancet Infectious Diseases. See previous version for less terse presentatio

    Investigation, Testing, and Selection of Slip-ring Lead Wires for Use in High-precision Slip-ring Capsules Final Report

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    Evaluation of corrosion resistant silver alloys for use in lead wires for slip-ring assemblies of Saturn guidance and control system

    Worrying and rumination are both associated with reduced cognitive control

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    Persistent negative thought is a hallmark feature of both major depressive disorder and generalized anxiety disorder. Despite its clinical significance, little is known about the underlying mechanisms of persistent negative thought. Recent studies suggest that reduced cognitive control might be an explanatory factor. We investigated the association between persistent negative thought and switching between internal representations in working memory, using the internal shift task (IST). The IST was administered to a group of undergraduates, classified as high-ruminators versus low-ruminators, or high-worriers versus low-worriers. Results showed that high-ruminators and high-worriers have more difficulties to switch between internal representations in working memory as opposed to low-ruminators and low-worriers. Importantly, results were only significant when the negative stimuli used in the IST reflected personally relevant worry themes for the participants. The results of this study indicate that rumination and worrying are both associated with reduced cognitive control for verbal information that is personally relevant
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