921 research outputs found

    A direct optical method for the study of grain boundary melting

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    The structure and evolution of grain boundaries underlies the nature of polycrystalline materials. Here we describe an experimental apparatus and light reflection technique for measuring disorder at grain boundaries in optically clear material, in thermodynamic equilibrium. The approach is demonstrated on ice bicrystals. Crystallographic orientation is measured for each ice sample. The type and concentration of impurity in the liquid can be controlled and the temperature can be continuously recorded and controlled over a range near the melting point. The general methodology is appropriate for a wide variety of materials.Comment: 8 pages, 8 figures, updated with minor changes made to published versio

    A Belief System's Organization Based on a Computational Model of the Dynamic Context: First Approximation

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    In this article we present a model of organization of a belief system based on a set of binary recursive functions that characterize the dynamic context that modifies the beliefs. The initial beliefs are modeled by a set of two-bit words that grow, update, and generate other beliefs as the different experiences of the dynamic context appear. Reason is presented as an emergent effect of the experience on the beliefs. The system presents a layered structure that allows a functional organization of the belief system. Our approach seems suitable to model different ways of thinking and to apply to different realistic scenarios such as ideologies

    Association of coronary vessel characteristics with outcome in patients with percutaneous coronary interventions with incomplete revascularization

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    © 2017 American Medical Association. All rights reserved. IMPORTANCE Many studies have compared outcomes for incomplete revascularization (IR) among patients undergoing percutaneous coronary interventions (PCI), but little is known about whether outcomes are related to the nature of the IR. OBJECTIVE To determine whether some coronary vessel characteristics are associated with worse outcomes in patients with PCI with IR. DESIGN, SETTING, AND PARTICIPANTS New York\u27s PCI registrywas used to examine mortality (median follow-up, 3.4 years) as a function of the number of vessels that were incompletely revascularized, the stenosis in those vessels, and whether the proximal left anterior descending artery was incompletely revascularized after controlling for other factors associated with mortality for patients with and without ST-elevationmyocardial infarction (STEMI). This was a multicenter study (all nonfederal PCI hospitals in New York State) that included 41 639 New York residents with multivessel coronary artery disease undergoing PCI in New York State between January 1, 2010, and December 31, 2012. EXPOSURES Percutaneous coronary interventions, with complete and incomplete revascularization. MAIN OUTCOMES AND MEASURES Medium-term mortality. RESULTS For patients with STEMI, the mean age was 62.8 years; 26.2%were women, 11.9% were Hispanic, and 81.5%were white. For other patients, the mean age was 66.6 years, 29.1%were women, 11.3%were Hispanic, and 79.1%were white. Incomplete revascularization was very common (78%among patients with STEMI and 71%among other patients). Patients with IR in a vessel with at least 90% stenosis were at higher risk than other patients with IR. This was not significant among patients with STEMI (17.18%vs 12.86%; adjusted hazard ratio [AHR], 1.16; 95%CI, 0.99-1.37) and significant among patients without STEMI (17.71% vs 12.96%; AHR, 1.15; 95%CI, 1.07-1.24). Similarly, patients with IR in 2 or more vessels had higher mortality than patients with completely revascularization and higher mortality than other patients with IR among patients with STEMI (20.37%vs 14.39%; AHR, 1.35; 95%CI, 1.15-1.59) and among patients without STEMI (20.10% vs 12.86%; AHR, 1.17; 95% CI, 1.09-1.59). Patients with proximal left anterior descending artery vessel IR had higher mortality than other patients with IR (20.09% vs 14.67%; AHR, 1.31; 95%CI, 1.04-1.64 for patients with STEMI and 20.78%vs 15.62%; AHR, 1.11; 95%CI, 1.01-1.23 for patients without STEMI). More than 20%of all PCI patients had IR of 2 or more vessels and more than 30% had IR with more than 90% stenosis. CONCLUSIONS AND RELEVANCE Patients with IR are at higher risk of mortality if they have IR with at least 90% stenosis, IR in 2 or more vessels, or proximal left anterior descending IR

    Light scattering from an isotropic layer between uniaxial crystals

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    We develop a model for the reflection and transmission of plane waves by an isotropic layer sandwiched between two uniaxial crystals of arbitrary orientation. In the laboratory frame, reflection and transmission coefficients corresponding to the principal polarization directions in each crystal are given explicitly in terms of the c-axis and propagation directions. The solution is found by first deriving explicit expressions for reflection and transmission amplitude coefficients for waves propagating from an arbitrarily oriented uniaxial anisotropic material into an isotropic material. By combining these results with Lekner's (1991) earlier treatment of waves propagating from isotropic media to anisotropic media and employing a matrix method we determine a solution to the general form of the multiple reflection case. The example system of a wetted interface between two ice crystals is used to contextualize the results.Comment: 18 pages, 9 figures,updated with changes made to published versio

    Defining and assessing spiritual health : a comparative study among 13- to 15-year-old pupils attending secular schools, Anglican schools, and private Christian schools in England and Wales

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    This article argues that the nation's commitment to young people involves proper concern for their physical health, their psychological health, and their spiritual health. In this context the notion of spiritual health is clarified by a critique of John Fisher's model of spiritual health. Fisher developed a relational model of spiritual health, which defines good spiritual health in terms of an individual's relationship to four domains: the personal, the communal, the environmental, and the transcendental. In the present analysis, we make comparisons between pupils educated in three types of schools: publicly funded schools without religious foundation, publicly funded schools with an Anglican foundation, and new independent Christian schools (not publicly funded). Our findings draw attention to significant differences in the levels of spiritual health experienced by pupils within these three types of schools
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