12,292 research outputs found

    Nematic cells with defect-patterned alignment layers

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    Using Monte Carlo simulations of the Lebwohl--Lasher model we study the director ordering in a nematic cell where the top and bottom surfaces are patterned with a lattice of ±1\pm 1 point topological defects of lattice spacing aa. We find that the nematic order depends crucially on the ratio of the height of the cell HH to aa. When H/a≳0.9H/a \gtrsim 0.9 the system is very well--ordered and the frustration induced by the lattice of defects is relieved by a network of half--integer defect lines which emerge from the point defects and hug the top and bottom surfaces of the cell. When H/a≲0.9H/a \lesssim 0.9 the system is disordered and the half--integer defect lines thread through the cell joining point defects on the top and bottom surfaces. We present a simple physical argument in terms of the length of the defect lines to explain these results. To facilitate eventual comparison with experimental systems we also simulate optical textures and study the switching behavior in the presence of an electric field

    File audit to assess sustained fidelity to a recovery and wellbeing oriented mental health service model: An Australian case study

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    2019 The Author(s). Background: Over the past decade there has been increasing attention to implementing recovery-oriented approaches within mental health service practice and enhancing fidelity to such approaches. However, as is often the case with evidence-based practices, less attention has been paid to the sustainability of recovery-oriented approaches over time. This study sought to investigate whether fidelity to a recovery-oriented practice framework - the Collaborative Recovery Model could be sustained over time. Method: The study setting was an Australian community managed mental health organisation. A file audit of consumer support plans was undertaken using the Goal and Action Plan Instrument for Quality audit tool (GAP-IQ). The audit tool assessed 17 areas for quality. Consumers (n = 116) from a large community managed mental health organisation participated in the study. Sustained fidelity to the Collaborative Recovery Model (CRM) was determined by comparing results from the file audit to a similar audit conducted 3 years earlier. Results: The file audit revealed a significant increase in fidelity to CRM practices between 2011 and 2014. Fidelity to individual audit items that comprise the GAP-IQ was also found to significantly increase across 16 of the 17 GAP-IQ audit items, with the exception of the \u27Action Plan Review\u27 audit item. Conclusions: A comparison of file audit data across different time points within the same setting can provide useful feedback about whether or not a practice is being sustained over time. Although fidelity increased overtime the study design does not allow conclusions that training and coaching practices implemented by the organisation were responsible

    China

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    Police Violence Against Black Protesters: A Public Health Issue

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    With the increased number of documented cases of violence perpetrated by police against protesters of the Black Lives Matter movement, public health officials are starting to list police violence as a health risk or a public health issue for black Americans. Using several timely theoretical explanations, we explore reasons why law enforcement officers routinely inflict violence against black protesters and avoid criminal stigma. Although police use of excessive force and untimely killings of blacks have always been criminal justice issues, the number of negative health consequences that are emerging after violent police confrontations implicates public health concerns. We argue that several strategies can be used to reduce police violence in the future

    Epithelial cell–derived secreted and transmembrane 1a signals to activated neutrophils during pneumococcal pneumonia

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    Airway epithelial cell responses are critical to the outcome of lung infection. In this study, we aimed to identify unique contributions of epithelial cells during lung infection. To differentiate genes induced selectively in epithelial cells during pneumonia, we compared genome-wide expression profiles from three sorted cell populations: epithelial cells from uninfected mouse lungs, epithelial cells from mouse lungs with pneumococcal pneumonia, and nonepithelial cells from those same infected lungs. Of 1,166 transcripts that were more abundant in epithelial cells from infected lungs compared with nonepithelial cells from the same lungs or from epithelial cells of uninfected lungs, 32 genes were identified as highly expressed secreted products. Especially strong signals included two related secreted and transmembrane (Sectm) 1 genes, Sectm1a and Sectm1b. Refinement of sorting strategies suggested that both Sectm1 products were induced predominantly in conducting airway epithelial cells. Sectm1 was induced during the early stages of pneumococcal pneumonia, and mutation of NF-kB RelA in epithelial cells did not diminish its expression. Instead, type I IFN signaling was necessary and sufficient for Sectm1 induction in lung epithelial cells, mediated by signal transducer and activator of transcription 1. For target cells, Sectm1a bound to myeloid cells preferentially, in particular Ly6GbrightCD11bbright neutrophils in the infected lung. In contrast, Sectm1a did not bind to neutrophils from uninfected lungs. Sectm1a increased expression of the neutrophil-attracting chemokine CXCL2 by neutrophils from the infected lung. We propose that Sectm1a is an epithelial product that sustains a positive feedback loop amplifying neutrophilic inflammation during pneumococcal pneumonia

    Identification of single-site gold catalysis in acetylene hydrochlorination

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    There remains considerable debate over the active form of gold under operating conditions of a recently validated gold catalyst for acetylene hydrochlorination. We have performed an in situ x-ray absorption fine structure study of gold/carbon (Au/C) catalysts under acetylene hydrochlorination reaction conditions and show that highly active catalysts comprise single-site cationic Au entities whose activity correlates with the ratio of Au(I):Au(III) present. We demonstrate that these Au/C catalysts are supported analogs of single-site homogeneous Au catalysts and propose a mechanism, supported by computational modeling, based on a redox couple of Au(I)-Au(III) species. View Full Tex

    Chiral Extrapolations and Exotic Meson Spectrum

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    We examine the chiral corrections to exotic meson masses calculated in lattice QCD. In particular, we ask whether the non-linear chiral behavior at small quark masses, which has been found in other hadronic systems, could lead to large corrections to the predictions of exotic meson masses based on linear extrapolations to the chiral limit. We find that our present understanding of exotic meson decay dynamics suggests that open channels may not make a significant contribution to such non-linearities whereas the virtual, closed channels may be important.Comment: 13 pagers, 2 figure
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