260 research outputs found

    Evaluation of a Water Channel-Based Platform for Characterizing Aerostat Flight Dynamics: A Case Study on a Lighter-Than-Air Wind Energy System

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140442/1/6.2014-2711.pd

    Decision Making Under Conditions of Uncertainty: Experimental Assessment of Decision Models

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    This research was supported by the National Defense University under Contract No. DABJ29-03-P-0084 and was a project of Texas A&M University's Institute for Science, Technology, and Public Policy in the George Bush School of Government and Public Service, Texas A&M University. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily relfect the views of the National Defense University.National Defense University (DABJ29-03-P-0084

    Determining the prevalence of tuberculosis in emergency departments in the Eastern Cape region of South Africa and the utility of the World Health Organization tuberculosis screening tool

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    Background. South Africa (SA) faces a significant tuberculosis (TB) burden complicated by high rates of HIV-TB co-infection. In SA, emergency departments (EDs) play an important role in screening for TB.Objectives. To determine the prevalence of TB in the ED and the effectiveness of the World Health Organization (WHO) TB screening tool.Methods. This was a cross-sectional observational study, conducted in the ED at Livingstone Hospital, Port Elizabeth, from 4 June to 15 July 2018. All patients aged >18 years and able to consent were administered the WHO TB screening questions and underwent a point-of-care HIV test and demographic data collection. Patients were followed up for 1 year and tracked in the National Health Laboratory Service database to determine TB status using laboratory testing.Results. Over the study period, 790 patients were enrolled. Overall, 121 patients (15.3%) were TB-positive, with 46 (38.0%) diagnosed after presenting to the ED and 75 (62.0%) with a previous TB history determined by self-report or confirmed laboratory testing. A greater proportion of the TB-positive patients were HIV-positive (49.6%) compared with the TB-negative population (24.8%). TB-positive individuals were more likely to present to the ED with a chief complaint of shortness of breath (SoB) (18.2%) compared with the TB-negative population (10.5%). Overall, the WHO TB screening tool had poor sensitivity (46.5%) and specificity (62.5%) for identifying TB-positive patients in the ED. A multiple logistic regression analysis, controlled for age and sex, showed HIV status (odds ratio (OR) 2.81; p<0.001) and SoB (OR 2.19; p<0.05) to be significant predictors of TB positivity. Adding positive HIV status and a presenting complaint of SoB increased sensitivity to 78.3%.Conclusions. EDs in SA face a high burden of TB. While WHO screening guidelines identify some of these patients, including routine HIV testing in the ED could significantly affect the number of TB diagnoses made

    Determining the prevalence of tuberculosis in emergency departments in the Eastern Cape region of South Africa and the utility of the World Health Organization tuberculosis screening tool

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    Background. South Africa (SA) faces a significant tuberculosis (TB) burden complicated by high rates of HIV-TB co-infection. In SA, emergency departments (EDs) play an important role in screening for TB. Objectives. To determine the prevalence of TB in the ED and the effectiveness of the World Health Organization (WHO) TB screening tool. Methods. This was a cross-sectional observational study, conducted in the ED at Livingstone Hospital, Port Elizabeth, from 4 June to 15 July 2018. All patients aged >18 years and able to consent were administered the WHO TB screening questions and underwent a point-of-care HIV test and demographic data collection. Patients were followed up for 1 year and tracked in the National Health Laboratory Service database to determine TB status using laboratory testing. Results. Over the study period, 790 patients were enrolled. Overall, 121 patients (15.3%) were TB-positive, with 46 (38.0%) diagnosed after presenting to the ED and 75 (62.0%) with a previous TB history determined by self-report or confirmed laboratory testing. A greater proportion of the TB-positive patients were HIV-positive (49.6%) compared with the TB-negative population (24.8%). TB-positive individuals were more likely to present to the ED with a chief complaint of shortness of breath (SoB) (18.2%) compared with the TB-negative population (10.5%). Overall, the WHO TB screening tool had poor sensitivity (46.5%) and specificity (62.5%) for identifying TB-positive patients in the ED. A multiple logistic regression analysis, controlled for age and sex, showed HIV status (odds ratio (OR) 2.81; p<0.001) and SoB (OR 2.19; p<0.05) to be significant predictors of TB positivity. Adding positive HIV status and a presenting complaint of SoB increased sensitivity to 78.3%. Conclusions. EDs in SA face a high burden of TB. While WHO screening guidelines identify some of these patients, including routine HIV testing in the ED could significantly affect the number of TB diagnoses made

    In vivo imaging and quantitative analysis of leukocyte directional migration and polarization in inflamed tissue

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    Directional migration of transmigrated leukocytes to the site of injury is a central event in the inflammatory response. Here, we present an in vivo chemotaxis assay enabling the visualization and quantitative analysis of subtype-specific directional motility and polarization of leukocytes in their natural 3D microenvironment. Our technique comprises the combination of i) semi-automated in situ microinjection of chemoattractants or bacteria as local chemotactic stimulus, ii) in vivo near-infrared reflected-light oblique transillumination (RLOT) microscopy for the visualization of leukocyte motility and morphology, and iii) in vivo fluorescence microscopy for the visualization of different leukocyte subpopulations or fluorescence-labeled bacteria. Leukocyte motility parameters are quantified off-line in digitized video sequences using computer-assisted single cell tracking. Here, we show that perivenular microinjection of chemoattractants [macrophage inflammatory protein-1alpha (MIP-1alpha/Ccl3), platelet-activating factor (PAF)] or E. coli into the murine cremaster muscle induces target-oriented intravascular adhesion and transmigration as well as polarization and directional interstitial migration of leukocytes towards the locally administered stimuli. Moreover, we describe a crucial role of Rho kinase for the regulation of directional motility and polarization of transmigrated leukocytes in vivo. Finally, combining in vivo RLOT and fluorescence microscopy in Cx3CR1(gfp/gfp) mice (mice exhibiting green fluorescent protein-labeled monocytes), we are able to demonstrate differences in the migratory behavior of monocytes and neutrophils.Taken together, we propose a novel approach for investigating the mechanisms and spatiotemporal dynamics of subtype-specific motility and polarization of leukocytes during their directional interstitial migration in vivo

    Mapping pervasive selective logging in the south-west Brazilian Amazon 2000–2019

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    Tropical forests harbour the highest biodiversity on the planet and are essential to human livelihoods and the global economy. However, continued loss and degradation of forested landscapes, coupled with a rapidly rising global population is placing incredible pressure on forests globally. The United Nations has developed the Reducing Emissions from Deforestation and forest Degradation (REDD+) programme in response to the challenges facing tropical forests and in recognition of the role they can play in climate mitigation. REDD+ requires consistent and reliable monitoring of forests, however, national-level methodologies for measuring degradation are often bespoke and, because of an inability to track degradation effectively, the majority of countries combine reporting for deforestation and forest degradation into a single value. Here, we extend a recent analysis that enabled the detection of selective logging at the scale of a logging concession to a regional-scale estimation of selective logging activities. We utilized logging records from across Brazil to train a supervised classification algorithm for detecting logged pixels in Landsat imagery then predicted the extent of logging over a 20 year period throughout Rondônia, Brazil. Approximately one-quarter of the forested lands in Rondônia were cleared between 2000 and 2019. We estimate that 11.0% of the forest area present in 2000 had been selectively logged by 2019, comprising >11,500 km2 of forest. In general, rates of selective logging were twice as high in the first decade relative to the last decade of the period. Our approach is a considerable advance in developing an operationalized selective logging monitoring system capable of detecting subtle forest disturbances over large spatial scales

    Complete mitochondrial DNA sequences provide new insights into the Polynesian motif and the peopling of Madagascar

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    More than a decade of mitochondrial DNA (mtDNA) studies have given the 'Polynesian motif' renowned status as a marker for tracing the late-Holocene expansion of Austronesian speaking populations. Despite considerable research on the Polynesian motif in Oceania, there has been little equivalent work on the western edge of its expansion - leaving major issues unresolved regarding the motif's evolutionary history. This has also led to considerable uncertainty regarding the settlement of Madagascar. In this study, we assess mtDNA variation in 266 individuals from three Malagasy ethnic groups: the Mikea, Vezo, and Merina. Complete mtDNA genome sequencing reveals a new variant of the Polynesian motif in Madagascar; two coding region mutations define a Malagasy-specific sub-branch. This newly defined 'Malagasy motif' occurs at high frequency in all three ethnic groups (13-50%), and its phylogenetic position, geographic distribution, and estimated age all support a recent origin, but without conclusively identifying a specific source region. Nevertheless, the haplotype's limited diversity, similar to those of other mtDNA haplogroups found in our Malagasy groups, best supports a small number of initial settlers arriving to Madagascar through the same migratory process. Finally, the discovery of this lineage provides a set of new polymorphic positions to help localize the Austronesian ancestors of the Malagasy, as well as uncover the origin and evolution of the Polynesian motif itself

    Resolving the ancestry of Austronesian-speaking populations

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    There are two very different interpretations of the prehistory of Island Southeast Asia (ISEA), with genetic evidence invoked in support of both. The “out-of-Taiwan” model proposes a major Late Holocene expansion of Neolithic Austronesian speakers from Taiwan. An alternative, proposing that Late Glacial/postglacial sea-level rises triggered largely autochthonous dispersals, accounts for some otherwise enigmatic genetic patterns, but fails to explain the Austronesian language dispersal. Combining mitochondrial DNA (mtDNA), Y-chromosome and genome-wide data, we performed the most comprehensive analysis of the region to date, obtaining highly consistent results across all three systems and allowing us to reconcile the models. We infer a primarily common ancestry for Taiwan/ISEA populations established before the Neolithic, but also detected clear signals of two minor Late Holocene migrations, probably representing Neolithic input from both Mainland Southeast Asia and South China, via Taiwan. This latter may therefore have mediated the Austronesian language dispersal, implying small-scale migration and language shift rather than large-scale expansion

    Will REDD+ safeguards mitigate corruption? Qualitative evidence from Southeast Asia

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    High levels of faith and finance are being invested in REDD+ as a promising global climate change mitigation policy. Since its inception in 2007, corruption has been viewed as a potential impediment to the achievement of REDD+ goals, partly motivating ‘safeguards’ rolled out as part of national REDD+ readiness activities. We compare corruption mitigation measures adopted as part of REDD+ safeguards, drawing on qualitative case evidence from three Southeast Asian countries that have recently piloted the scheme: Indonesia, the Philippines, and Vietnam. We find that while REDD+ safeguards adopt a conventional principal-agent approach to tackling corruption in the schemes, our case evidence confirms our theoretical expectation that REDD+ corruption risks are perceived to arise not only from principal-agent type problems: they are also linked to embedded pro-corruption social norms. This implies that REDD+ safeguards are likely to be at best partially effective against corruption, and at worst will not mitigate corruption at all

    Removing leakage-induced correlated errors in superconducting quantum error correction

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    Quantum computing can become scalable through error correction, but logical error rates only decrease with system size when physical errors are sufficiently uncorrelated. During computation, unused high energy levels of the qubits can become excited, creating leakage states that are long-lived and mobile. Particularly for superconducting transmon qubits, this leakage opens a path to errors that are correlated in space and time. Here, we report a reset protocol that returns a qubit to the ground state from all relevant higher level states. We test its performance with the bit-flip stabilizer code, a simplified version of the surface code for quantum error correction. We investigate the accumulation and dynamics of leakage during error correction. Using this protocol, we find lower rates of logical errors and an improved scaling and stability of error suppression with increasing qubit number. This demonstration provides a key step on the path towards scalable quantum computing
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