3,852 research outputs found

    Preparing for operation GRITROCK : military medical ethics challenges encountered in the planning stages of the UK Ebola response mission

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    In early September 2014, Médecins sans Frontières (MSF) took the unusual step of calling on governments to deploy military, as well as civilian, assets to help combat the Ebola Virus Disease (EVD) epidemic raging in West Africa (MSF, 2014). The UK government announced a package of aid in response to the outbreak, including the deployment of military experts, targeted primarily on Sierra Leone. (Gov.UK 2014) The scale of the outbreak and the responses to it attracted comment from many quarters and raised ethical issues. We were interested in the ethical challenges that would confront the troops on the ground in Sierra Leone, particularly those who were healthcare professionals. We successfully secured UK funding council research funds to explore these challenges. During the preparatory stages of this project, however, it became clear that ethical decisions had also been made during the planning stages of the deployment in anticipation of issue that may be faced on the deployment. These planning issues are of interest in their own right, even though they fell outside the aims of our project, and we explore of some these in this chapter

    Panchromatic Imaging of a Transitional Disk: The Disk of GM Aur in Optical and FUV Scattered Light

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    We have imaged GM Aur with HST, detected its disk in scattered light at 1400A and 1650A, and compared these with observations at 3300A, 5550A, 1.1 microns, and 1.6 microns. The scattered light increases at shorter wavelengths. The radial surface brightness profile at 3300A shows no evidence of the 24AU radius cavity that has been previously observed in sub-mm observations. Comparison with dust grain opacity models indicates the surface of the entire disk is populated with sub-micron grains. We have compiled an SED from 0.1 microns to 1 mm, and used it to constrain a model of the star+disk system that includes the sub-mm cavity using the Monte Carlo Radiative Transfer code by Barbara Whitney. The best-fit model image indicates that the cavity should be detectable in the F330W bandpass if the cavity has been cleared of both large and small dust grains, but we do not detect it. The lack of an observed cavity can be explained by the presence of sub-microns grains interior to the sub-mm cavity wall. We suggest one explanation for this which could be due to a planet of mass <9 Jupiter masses interior to 24 AU. A unique cylindrical structure is detected in the FUV data from the Advanced Camera for Surveys/Solar Blind Channel. It is aligned along the system semi-minor axis, but does not resemble an accretion-driven jet. The structure is limb-brightened and extends 190 +/- 35 AU above the disk midplane. The inner radius of the limb-brightening is 40 +/- 10 AU, just beyond the sub-millimeter cavity wall.Comment: 40 pages, 11 figures, 4 tables, accepted to Ap

    On tilt and curvature dependent errors and the calibration of coherence scanning interferometry

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    Although coherence scanning interferometry (CSI) is capable of measuring surface topography with sub-nanometre precision, it is well known that the performance of measuring instruments depends strongly on the local tilt and curvature of the sample surface. Based on 3D linear systems theory, however, a recent analysis of fringe generation in CSI provides a method to characterize the performance of surface measuring instruments and offers considerable insight into the origins of these errors. Furthermore, from the measurement of a precision sphere, a process to calibrate and partially correct instruments has been proposed. This paper presents, for the first time, a critical look at the calibration and correction process. Computational techniques are used to investigate the effects of radius error and measurement noise introduced during the calibration process for the measurement of spherical and sinusoidal profiles. Care is taken to illustrate the residual tilt and curvature dependent errors in a manner that will allow users to estimate measurement uncertainty. It is shown that by calibrating the instrument correctly and using appropriate methods to extract phase from the resulting fringes (such as frequency domain analysis), CSI is capable of measuring the topography of surfaces with varying tilt with sub nanometre accuracy

    Genetic associations with childhood brain growth, defined in two longitudinal cohorts

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    Genome-wide association studies (GWASs) are unraveling the genetics of adult brain neuroanatomy as measured by cross-sectional anatomic magnetic resonance imaging (aMRI). However, the genetic mechanisms that shape childhood brain development are, as yet, largely unexplored. In this study we identify common genetic variants associated with childhood brain development as defined by longitudinal aMRI. Genome-wide single nucleotide polymorphism (SNP) data were determined in two cohorts: one enriched for attention-deficit/hyperactivity disorder (ADHD) (LONG cohort: 458 participants; 119 with ADHD) and the other from a population-based cohort (Generation R: 257 participants). The growth of the brain's major regions (cerebral cortex, white matter, basal ganglia, and cerebellum) and one region of interest (the right lateral prefrontal cortex) were defined on all individuals from two aMRIs, and a GWAS and a pathway analysis were performed. In addition, association between polygenic risk for ADHD and brain growth was determined for the LONG cohort. For white matter growth, GWAS meta-analysis identified a genome-wide significant intergenic SNP (rs12386571, P = 9.09 × 10-9 ), near AKR1B10. This gene is part of the aldo-keto reductase superfamily and shows neural expression. No enrichment of neural pathways was detected and polygenic risk for ADHD was not associated with the brain growth phenotypes in the LONG cohort that was enriched for the diagnosis of ADHD. The study illustrates the use of a novel brain growth phenotype defined in vivo for further study

    The Extent Of Wetland Vegetation And Wetness Change At Eufaula National Wildlife Refuge From 1984-2012 Examined Using Landsat Thematic Mapper And Enhanced Thematic Mapper Plus Imagery

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    Wetlands provide functions such as reducing flooding of surrounding areas and acting as a rest stop for migrating birds. Eufaula National Wildlife Refuge in Alabama has a natural wetland and six artificial wetlands that are differentiated by how they are drained. Remote sensing derived normalized difference vegetation index and normalized difference wetness indexes were used to obtain information about vegetation and wetness at the wetlands from 1984-2011. A correlation analysis was performed to assess the degree of association between vegetation and wetness as a function of management practices. An ANOVA and agglomerative hierarchical clustering were performed to assess the degree of similarity among the different wetlands based on vegetation and wetness. From the results of the correlation analysis, it was found that there is a statistically significant association between vegetation and wetness. The ANOVA and agglomerative hierarchical clustering suggest that wetlands that are managed similarly have a similar association between vegetation and wetness

    Extreme Asymmetry in the Disk of V1247 Ori

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    We present the first near-infrared scattered-light detection of the transitional disk around V1247 Ori, which was obtained using high-resolution polarimetric differential imaging observations with Subaru/HiCIAO. Our imaging in the H band reveals the disk morphology at separations of ~0.14"-0.86" (54-330 au) from the central star. The polarized intensity (PI) image shows a remarkable arc-like structure toward the southeast of the star, whereas the fainter northwest region does not exhibit any notable features. The shape of the arm is consistent with an arc of 0.28" ±\pm 0.09" in radius (108 au from the star), although the possibility of a spiral arm with a small pitch angle cannot be excluded. V1247 Ori features an exceptionally large azimuthal contrast in scattered, polarized light; the radial peak of the southeastern arc is about three times brighter than the northwestern disk measured at the same distance from the star. Combined with the previous indication of an inhomogeneous density distribution in the gap at \lesssim46 au, the notable asymmetry in the outer disk suggests the presence of unseen companions and/or planet-forming processes ongoing in the arc.Comment: 21 pages, 5 figures, accepted for publication in PAS

    The Feasibility of Using Data-Driven Algorithmic Recommendations for Refugee Placement in Norway

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    A growing body of research suggests that refugees’ initial settlement area can have a long-run impact on subsequent integration outcomes. As a result, matching refugees and asylum seekers to initial locations where they are likely to succeed holds the potential to improve their labor market integration. In this report we focus on the GeoMatch algorithm, which is a recommendation tool that provides settlement officers with data-driven location recommendations for incoming refugees and asylum seekers. Leveraging machine learning on historical data, the tool predicts labor market outcomes for individuals across possible settlement areas. A flexible allocation algorithm then provides location recommendations for each family unit while taking capacity constraints into account. Drawing on administrative data from Statistics Norway and incorporating a set of realistic constraints, we find that using GeoMatch recommendations could improve refugees’ monthly earnings by up to 55% over baseline. The report ends with a discussion of how the tool can be implemented in the Norwegian context.The Feasibility of Using Data-Driven Algorithmic Recommendations for Refugee Placement in NorwaypublishedVersio

    SEEDS Adaptive Optics Imaging of the Asymmetric Transition Disk Oph IRS 48 in Scattered Light

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    We present the first resolved near infrared imagery of the transition disk Oph IRS 48 (WLY 2-48), which was recently observed with ALMA to have a strongly asymmetric sub-millimeter flux distribution. H-band polarized intensity images show a \sim60AU radius scattered light cavity with two pronounced arcs of emission, one from Northeast to Southeast and one smaller, fainter and more distant arc in the Northwest. K-band scattered light imagery reveals a similar morphology, but with a clear third arc along the Southwestern rim of the disk cavity. This arc meets the Northwestern arc at nearly a right angle, revealing the presence of a spiral arm or local surface brightness deficit in the disk, and explaining the East-West brightness asymmetry in the H-band data. We also present 0.8-5.4μ\mum IRTF SpeX spectra of this object, which allow us to constrain the spectral class to A0±\pm1 and measure a low mass accretion rate of 108.5^{-8.5}M_{\odot}/yr, both consistent with previous estimates. We investigate a variety of reddening laws in order to fit the mutliwavelength SED of Oph IRS 48 and find a best fit consistent with a younger, higher luminosity star than previous estimates.Comment: Accepted by ApJ. 19 pages, 15 figure

    Attention-deficit hyperactivity disorder symptoms and brain morphology:Addressing potential selection bias with inverse probability weighting

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    The goal of this study was to examine what happens to established associations between attention deficit hyperactivity disorder (ADHD) symptoms and cortical surface and thickness regions once we apply inverse probability of censoring weighting (IPCW) to address potential selection bias. Moreover, we illustrate how different factors that predict participation contribute to potential selection bias. Participants were 9- to 11-year-old children from the Generation R study (N = 2707). Cortical area and thickness were measured with magnetic resonance imaging (MRI) and ADHD symptoms with the Child Behavior Checklist. We examined how associations between ADHD symptoms and brain morphology change when we weight our sample back to either follow-up (ages 9–11), baseline (cohort at birth), or eligible (population of Rotterdam at time of recruitment). Weights were derived using IPCW or raking and missing predictors of participation used to estimate weights were imputed. Weighting analyses to baseline and eligible increased beta coefficients for the middle temporal gyrus surface area, as well as fusiform gyrus cortical thickness. Alternatively, the beta coefficient for the rostral anterior cingulate decreased. Removing one group of variables used for estimating weights resulted in the weighted regression coefficient moving closer to the unweighted regression coefficient. In addition, we found considerably different beta coefficients for most surface area regions and all thickness measures when we did not impute missing covariate data. Our findings highlight the importance of using inverse probability weighting (IPW) in the neuroimaging field, especially in the context of mental health-related research. We found that including all variables related to exposure-outcome in the IPW model and combining IPW with multiple imputations can help reduce bias. We encourage future psychiatric neuroimaging studies to define their target population, collect information on eligible but not included participants and use inverse probability of censoring weighting (IPCW) to reduce selection bias.</p
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