5,150 research outputs found

    PS-FCN: A Flexible Learning Framework for Photometric Stereo

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    This paper addresses the problem of photometric stereo for non-Lambertian surfaces. Existing approaches often adopt simplified reflectance models to make the problem more tractable, but this greatly hinders their applications on real-world objects. In this paper, we propose a deep fully convolutional network, called PS-FCN, that takes an arbitrary number of images of a static object captured under different light directions with a fixed camera as input, and predicts a normal map of the object in a fast feed-forward pass. Unlike the recently proposed learning based method, PS-FCN does not require a pre-defined set of light directions during training and testing, and can handle multiple images and light directions in an order-agnostic manner. Although we train PS-FCN on synthetic data, it can generalize well on real datasets. We further show that PS-FCN can be easily extended to handle the problem of uncalibrated photometric stereo.Extensive experiments on public real datasets show that PS-FCN outperforms existing approaches in calibrated photometric stereo, and promising results are achieved in uncalibrated scenario, clearly demonstrating its effectiveness.Comment: ECCV 2018: https://guanyingc.github.io/PS-FC

    Effect of water vapor on the spallation of thermal barrier coating systems during laboratory cyclic oxidation testing.

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    The effect of water and water vapor on the lifetime of Ni-based superalloy samples coated with a typical thermal barrier coating system—b-(Ni,Pt)Al bond coat and yttria stabilized zirconia (YSZ) top coat deposited by electron beam physical vapor deposition (EB-PVD) was studied. Samples were thermally cycled to 1,150 C and subjected to a water-drop test in order to elucidate the effect of water vapor on thermal barrier coating (TBC) spallation. It was shown that the addition of water promotes spallation of TBC samples after a given number of cycles at 1,150 C. This threshold was found to be equal to 170 cycles for the present system. Systems based on b-NiAl bond coat or on Pt-rich c/c0 bond coat were also sensitive to the water-drop test. Moreover, it was shown that water vapor in ambient air after minutes or hours at room temperature, promotes also TBC spallation once the critical number of cycles has been reached. This desktop spalling (DTS) can be prevented by locking up the cycled samples in a dry atmosphere box. These results for TBC systems confirm and document Smialek’s theory about DTS and moisture induced delayed spalling (MIDS) being the same phenomenon. Finally, the mechanisms implying hydrogen embrittlement or surface tension modifications are discussed

    Moving from evidence-based medicine to evidence-based health.

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    While evidence-based medicine (EBM) has advanced medical practice, the health care system has been inconsistent in translating EBM into improvements in health. Disparities in health and health care play out through patients' limited ability to incorporate the advances of EBM into their daily lives. Assisting patients to self-manage their chronic conditions and paying attention to unhealthy community factors could be added to EBM to create a broader paradigm of evidence-based health. A perspective of evidence-based health may encourage physicians to consider their role in upstream efforts to combat socially patterned chronic disease

    Historical photogrammetry: Bird's Paluxy River dinosaur chase sequence digitally reconstructed as it was prior to excavation 70 years ago.

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    It is inevitable that some important specimens will become lost or damaged over time, conservation is therefore of vital importance. The Paluxy River dinosaur tracksite is among the most famous in the world. In 1940, Roland T. Bird described and excavated a portion of the site containing associated theropod and sauropod trackways. This excavated trackway was split up and housed in different institutions, and during the process a portion was lost or destroyed. We applied photogrammetric techniques to photographs taken by Bird over 70 years ago, before the trackway was removed, to digitally reconstruct the site as it was prior to excavation. The 3D digital model offers the opportunity to corroborate maps drawn by R.T. Bird when the tracksite was first described. More broadly, this work demonstrates the exciting potential for digitally recreating palaeontological, geological, or archaeological specimens that have been lost to science, but for which photographic documentation exists

    Evaluation of the fracture performance of different rubberised bitumens based on the essential work of fracture

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    The fracture performance of rubberised bitumen in addition to one pre-treated with a Warm Mix Additive (Sasobit®) was investigated using different test methods measuring different damage mechanisms. Two Recycled Tyre Rubber (RTR) modifiers together with two base binders were blended in the laboratory to produce various combinations of Recycled Tyre Rubber Modified Bitumens (RTR-MBs). The first RTR is a standard recycled polymer derived from discarded truck and passenger car tyres by ambient grinding. The second RTR consists of 100% recycled truck tyres derived by cryogenic grinding and pre-treated with special oil and WMA to allow further decrease of asphalt mixture production temperatures. A fracture mechanics testing approach was used for evaluating the binder fatigue resistance; consisting of the double-edge-notched tension (DENT) test. The critical tip opening displacement (CTOD) obtained from the DENT test was used for fracture characterization of the binders within the ductile failure region. The study applied the partitioning concept of the total energy of bituminous binders to have a more reliable parameter that could be independent of the stress state of the ligament. The results show that generally the addition of RTR improves the fracture properties of binders indicating better fatigue performance. Pre-treatment with Sasobit® makes the materials more brittle and hence more susceptible to fracture

    Severe childhood malaria syndromes defined by plasma proteome profiles

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    BACKGROUND Cerebral malaria (CM) and severe malarial anemia (SMA) are the most serious life-threatening clinical syndromes of Plasmodium falciparum infection in childhood. Therefore it is important to understand the pathology underlying the development of CM and SMA, as opposed to uncomplicated malaria (UM). Different host responses to infection are likely to be reflected in plasma proteome-patterns that associate with clinical status and therefore provide indicators of the pathogenesis of these syndromes. METHODS AND FINDINGS Plasma and comprehensive clinical data for discovery and validation cohorts were obtained as part of a prospective case-control study of severe childhood malaria at the main tertiary hospital of the city of Ibadan, an urban and densely populated holoendemic malaria area in Nigeria. A total of 946 children participated in this study. Plasma was subjected to high-throughput proteomic profiling. Statistical pattern-recognition methods were used to find proteome-patterns that defined disease groups. Plasma proteome-patterns accurately distinguished children with CM and with SMA from those with UM, and from healthy or severely ill malaria-negative children. CONCLUSIONS We report that an accurate definition of the major childhood malaria syndromes can be achieved using plasma proteome-patterns. Our proteomic data can be exploited to understand the pathogenesis of the different childhood severe malaria syndromes

    The evolution of reproductive isolation in a simultaneous hermaphrodite, the freshwater snail Physa

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    <p>Abstract</p> <p>Background</p> <p>The cosmopolitan freshwater snail <it>Physa acuta </it>has recently found widespread use as a model organism for the study of mating systems and reproductive allocation. Mitochondrial DNA phylogenies suggest that <it>Physa carolinae</it>, recently described from the American southeast, is a sister species of <it>P. acuta</it>. The divergence of the <it>acuta/carolinae </it>ancestor from the more widespread <it>P. pomilia </it>appears to be somewhat older, and the split between a hypothetical <it>acuta/carolinae/pomilia </it>ancestor and <it>P. gyrina </it>appears older still.</p> <p>Results</p> <p>Here we report the results of no-choice mating experiments yielding no evidence of hybridization between <it>gyrina </it>and any of four other populations (<it>pomilia, carolinae</it>, Philadelphia <it>acuta</it>, or Charleston <it>acuta</it>), nor between <it>pomilia </it>and <it>carolinae</it>. Crosses between <it>pomilia </it>and both <it>acuta </it>populations yielded sterile F1 progeny with reduced viability, while crosses between <it>carolinae </it>and both <it>acuta </it>populations yielded sterile F1 hybrids of normal viability. A set of mate-choice tests also revealed significant sexual isolation between <it>gyrina </it>and all four of our other <it>Physa </it>populations, between <it>pomilia </it>and <it>carolinae</it>, and between <it>pomilia </it>and Charleston <it>acuta</it>, but not between <it>pomilia </it>and the <it>acuta </it>population from Philadelphia, nor between <it>carolinae </it>and either <it>acuta </it>population. These observations are consistent with the origin of hybrid sterility prior to hybrid inviability, and a hypothesis that speciation between <it>pomilia </it>and <it>acuta </it>may have been reinforced by selection for prezygotic reproductive isolation in sympatry.</p> <p>Conclusions</p> <p>We propose a two-factor model for the evolution of postzygotic reproductive incompatibility in this set of five <it>Physa </it>populations consistent with the Dobzhansky-Muller model of speciation, and a second two-factor model for the evolution of sexual incompatibility. Under these models, species trees may be said to correspond with gene trees in American populations of the freshwater snail, <it>Physa</it>.</p
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