1,239 research outputs found

    Asymmetries in Mars' Exosphere: Implications for X-ray and ENA Imaging

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    Observations and simulations show that Mars' atmosphere has large seasonal variations. Total atmospheric density can have an order of magnitude latitudinal variation at exobase heights. By numerical simulations we show that these latitude variations in exobase parameters induce asymmetries in the hydrogen exosphere that propagate to large distances from the planet. We show that these asymmetries in the exosphere produce asymmetries in the fluxes of energetic neutral atoms (ENAs) and soft X-rays produced by charge exchange between the solar wind and exospheric hydrogen. This could be an explanation for asymmetries that have been observed in ENA and X-ray fluxes at Mars.Comment: Submitted to Space Science Review. v2: Minor changes in text and figure

    Measuring service outcomes for adaptive preventive maintenance

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    Services account for an increasing share of economic activity in the western world. As part of this, preventive maintenance (PM) service volumes are constantly growing as a result of a growing (and aging) asset population and maintenance outsourcing. While the pursuit of improved service productivity is in the interest of both firms and nations, the challenges of measuring service performance, and more specifically service outcomes, persist. This paper presents an outcome-based measure for fleet PM, which has far-reaching implications considering service productivity and performance measurement. We develop a statistical process control based measure that utilizes data typically available in PM. The measure is grounded in reliability theory, which enables generalization of the measure within PM services but also outlines the limitations of its application. Finally we apply the measure in a PM field service process of a servitized equipment manufacturer. Based on actual maintenance records we show that the service provider could reduce their service output by at least 5–10% without significantly affecting the aggregate service outcome. The developed measure and control process form the basis for adaptive preventive maintenance, which is expected to facilitate the transition towards outcome-based contracts through complementing condition-based maintenance. One of the key benefits of the approach is that it provides a cost-effective way of revealing the scarcely studied phenomenon of service overproduction. Based on our case, we conclude that there are significant productivity gains in making sure that you meet required standards for service output but do not exceed them

    Researching Cooperation and Communication in Continuous Software Engineering

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    Continuous Software Engineering (CSE) - -continuous development and deployment of software - -and DevOps - -the close cooperation or integration of operations and software development - -is about to change how software is developed. Together with the tighter integration of development and operations also with usage this will change coordination and collaboration both between IT professionals and between developers and users. In this short paper, we discuss the CHASE dimension of three core research themes that begin to crystallize in literature. This position paper is intended as a 'call to arms' for the CHASE community to study CSE

    An open and parallel multiresolution framework using block-based adaptive grids

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    A numerical approach for solving evolutionary partial differential equations in two and three space dimensions on block-based adaptive grids is presented. The numerical discretization is based on high-order, central finite-differences and explicit time integration. Grid refinement and coarsening are triggered by multiresolution analysis, i.e. thresholding of wavelet coefficients, which allow controlling the precision of the adaptive approximation of the solution with respect to uniform grid computations. The implementation of the scheme is fully parallel using MPI with a hybrid data structure. Load balancing relies on space filling curves techniques. Validation tests for 2D advection equations allow to assess the precision and performance of the developed code. Computations of the compressible Navier-Stokes equations for a temporally developing 2D mixing layer illustrate the properties of the code for nonlinear multi-scale problems. The code is open source

    Effect of Donor Simvastatin Treatment on Gene Expression Profiles in Human Cardiac Allografts during Ischemia-Reperfusion Injury

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    Purpose Numerous studies have shown that statin therapy initiated early after heart transplantation has beneficial effects on the development of cardiac allograft vasculopathy. Recently, we were able to show in a randomized clinical trial that simvastatin treatment of brain-dead donors conditions the heart transplant to withstand ischemia-reperfusion injury and to reduce the need for rejection treatments early after transplantation. In this study, we analyzed myocardial gene expression profiles in cardiac allografts after donor simvastatin treatment. Methods 84 heart transplant donors received 80 mg of simvastatin via nasogastric tube (n=42), or no treatment (n=42) in a prospective, double-blinded randomized controlled trial. Transmural Tru-Cut biopsies were taken from the apex of left ventricle of the donor heart immediately before reperfusion and 1 hour after reperfusion. 20 heart biopsies from donors without treatment and 20 heart biopsies from donors with simvastatin treatment will be analyzed with RNA sequencing. Results The preliminary analysis of RNA sequencing data from myocardial biopsies revealed altogether 137 significantly differentially expressed genes in all pairwise comparisons. The overall biological functions of these genes were related to gene ontology terms such as response to toxic substance, leukocyte migration, neutrophil mediated immunity, response to lipopolysaccharide, and response to oxidative stress. At the KEGG pathway level, our results indicated alterations in IL-17, TNF, MAPK and the AGE-RAGE signaling pathways. Conclusion We have shown in previous studies that donor simvastatin treatment induces protective effects against IRI in heart transplant recipients. In this study, we were able to detect significantly differentially expressed genes related to effects of simvastatin treatment. In order to single out genes that show beneficial effects of simvastatin treatment, further analysis will be conducted by exploring gene expression changes in specific biological functional categories, such as interleukin signaling and neutrophil degranulation. The complete analysis will be presented at the ISHLT 2019 congress.Peer reviewe

    Label-Free Proteomics Approach Characterizes Plasma Protein Signature of Donor Brain Death

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    Purpose Despite recent advances in donation after circulatory death, transplants from brain-dead donors remain the sole source in heart transplantation (HTx) worldwide. Due to organ shortage, marginal donors are increasingly used and the utilization of transplants becomes markedly more challenging. They undergo invariably brain death that induces a systemic cytokine and catecholamine storm that lead to systemic inflammation, labile hemodynamics, and organ hypoperfusion. Together, these can damage the heart and aggravate later occurring graft injury, and ultimately, compromise graft function. However, the effect of donor brain death on allografts is not well understood. Methods In a separate prospective, blinded single-center trial, we collected donor plasma samples and relevant clinical patient data from 50 HTx brain-dead donors and as controls plasma samples from age- and gender-matched 23 healthy volunteers. Quantitative label-free proteomics in high definition MSE mode (HDMSE) was carried out on the samples. Various statistical analyses were performed on quantitative proteomics data to obtain the most reliably distinguishing proteins, which classify the donors vs controls. Results With two or more unique proteins per identification, 463 proteins were quantified in our pilot study. A complete separation between donors and controls based on a set of 278 proteins (p-valuePeer reviewe
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