2,231 research outputs found

    InfiniTAM v3: A Framework for Large-Scale 3D Reconstruction with Loop Closure

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    Volumetric models have become a popular representation for 3D scenes in recent years. One breakthrough leading to their popularity was KinectFusion, which focuses on 3D reconstruction using RGB-D sensors. However, monocular SLAM has since also been tackled with very similar approaches. Representing the reconstruction volumetrically as a TSDF leads to most of the simplicity and efficiency that can be achieved with GPU implementations of these systems. However, this representation is memory-intensive and limits applicability to small-scale reconstructions. Several avenues have been explored to overcome this. With the aim of summarizing them and providing for a fast, flexible 3D reconstruction pipeline, we propose a new, unifying framework called InfiniTAM. The idea is that steps like camera tracking, scene representation and integration of new data can easily be replaced and adapted to the user's needs. This report describes the technical implementation details of InfiniTAM v3, the third version of our InfiniTAM system. We have added various new features, as well as making numerous enhancements to the low-level code that significantly improve our camera tracking performance. The new features that we expect to be of most interest are (i) a robust camera tracking module; (ii) an implementation of Glocker et al.'s keyframe-based random ferns camera relocaliser; (iii) a novel approach to globally-consistent TSDF-based reconstruction, based on dividing the scene into rigid submaps and optimising the relative poses between them; and (iv) an implementation of Keller et al.'s surfel-based reconstruction approach.Comment: This article largely supersedes arxiv:1410.0925 (it describes version 3 of the InfiniTAM framework

    Comparison of risk scoring systems for patients presenting with upper gastrointestinal bleeding: international multicentre prospective study

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    Objective: To compare the predictive accuracy and clinical utility of five risk scoring systems in the assessment of patients with upper gastrointestinal bleeding. Design: International multicentre prospective study. Setting: Six large hospitals in Europe, North America, Asia, and Oceania. Participants: 3012 consecutive patients presenting over 12 months with upper gastrointestinal bleeding. Main outcome measures: Comparison of pre-endoscopy scores (admission Rockall, AIMS65, and Glasgow Blatchford) and post-endoscopy scores (full Rockall and PNED) for their ability to predict predefined clinical endpoints: a composite endpoint (transfusion, endoscopic treatment, interventional radiology, surgery, or 30 day mortality), endoscopic treatment, 30 day mortality, rebleeding, and length of hospital stay. Optimum score thresholds to identify low risk and high risk patients were determined. Results: The Glasgow Blatchford score was best (area under the receiver operating characteristic curve (AUROC) 0.86) at predicting intervention or death compared with the full Rockall score (0.70), PNED score (0.69), admission Rockall score (0.66, and AIMS65 score (0.68) (all P<0.001). A Glasgow Blatchford score of ≤1 was the optimum threshold to predict survival without intervention (sensitivity 98.6%, specificity 34.6%). The Glasgow Blatchford score was better at predicting endoscopic treatment (AUROC 0.75) than the AIMS65 (0.62) and admission Rockall scores (0.61) (both P<0.001). A Glasgow Blatchford score of ≥7 was the optimum threshold to predict endoscopic treatment (sensitivity 80%, specificity 57%). The PNED (AUROC 0.77) and AIMS65 scores (0.77) were best at predicting mortality, with both superior to admission Rockall score (0.72) and Glasgow Blatchford score (0.64; P<0.001). Score thresholds of ≥4 for PNED, ≥2 for AIMS65, ≥4 for admission Rockall, and ≥5 for full Rockall were optimal at predicting death, with sensitivities of 65.8-78.6% and specificities of 65.0-65.3%. No score was helpful at predicting rebleeding or length of stay. Conclusions: The Glasgow Blatchford score has high accuracy at predicting need for hospital based intervention or death. Scores of ≤1 appear the optimum threshold for directing patients to outpatient management. AUROCs of scores for the other endpoints are less than 0.80, therefore their clinical utility for these outcomes seems to be limited. Trial registration: Current Controlled Trials ISRCTN16235737

    In vitro comparison of the effects of rough and polished stem surface finish on pressure generation in cemented hip arthroplasty

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    Background and purpose High pressures around implants can cause bone lysis and loosening. We investigated how pressures are generated around cemented femoral stems

    Averting wildlife-borne infectious disease epidemics requires a focus on socio-ecological drivers and a redesign of the global food system.

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    A debate has emerged over the potential socio-ecological drivers of wildlife-origin zoonotic disease outbreaks and emerging infectious disease (EID) events. This Review explores the extent to which the incidence of wildlife-origin infectious disease outbreaks, which are likely to include devastating pandemics like HIV/AIDS and COVID-19, may be linked to excessive and increasing rates of tropical deforestation for agricultural food production and wild meat hunting and trade, which are further related to contemporary ecological crises such as global warming and mass species extinction. Here we explore a set of precautionary responses to wildlife-origin zoonosis threat, including: (a) limiting human encroachment into tropical wildlands by promoting a global transition to diets low in livestock source foods; (b) containing tropical wild meat hunting and trade by curbing urban wild meat demand, while securing access for indigenous people and local communities in remote subsistence areas; and (c) improving biosecurity and other strategies to break zoonosis transmission pathways at the wildlife-human interface and along animal source food supply chains

    Quantitative association tests of immune responses to antigens of Mycobacterium tuberculosis: a study of twins in West Africa.

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    There is now considerable evidence that host genetic factors are important in determining the outcome of infection with Mycobacterium tuberculosis (MTB). The aim of this study was to assess the role of several candidate genes in the variation observed in the immune responses to MTB antigens. In-vitro assays of T-cell proliferation, an in-vivo intradermal delayed hypersensitivity response; cytokine and antibody secretions to several mycobacterial peptide antigens were assessed in healthy, but exposed, West African twins. Candidate gene polymorphisms were typed in the NRAMP1, Vitamin D receptor, IL10, IL4, IL4 receptor and CTLA-4 genes. Variants of the loci IL10 (-1082 G/A), CTLA-4 (49 A/G) and the IL4 receptor (128 A/G) showed significant associations with immune responses to several antigens. T-cell proliferative responses and antibody responses were reduced, TNF-alpha responses were increased for subjects with the CTLA-4 G allele. The T-cell proliferative responses of subjects with IL10 GA and GG genotypes differed significantly. IL4 receptor AG and GG genotypes also showed significant differences in their T-cell proliferative responses to MTB antigens. These results yield a greater understanding of the genetic mechanisms that underlie the immune responses in tuberculosis and have implications for the design of therapeutic interventions

    The ratio of monocytes to lymphocytes in peripheral blood correlates with increased susceptibility to clinical malaria in Kenyan children.

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    BACKGROUND: Plasmodium falciparum malaria remains a major cause of illness and death in sub-Saharan Africa. Young children bear the brunt of the disease and though older children and adults suffer relatively fewer clinical attacks, they remain susceptible to asymptomatic P. falciparum infection. A better understanding of the host factors associated with immunity to clinical malaria and the ability to sustain asymptomatic P. falciparum infection will aid the development of improved strategies for disease prevention. METHODS AND FINDINGS: Here we investigate whether full differential blood counts can predict susceptibility to clinical malaria among Kenyan children sampled at five annual cross-sectional surveys. We find that the ratio of monocytes to lymphocytes, measured in peripheral blood at the time of survey, directly correlates with risk of clinical malaria during follow-up. This association is evident among children with asymptomatic P. falciparum infection at the time the cell counts are measured (Hazard ratio (HR)  =  2.7 (95% CI 1.42, 5.01, P  =  0.002) but not in those without detectable parasitaemia (HR  =  1.0 (95% CI 0.74, 1.42, P  =  0.9). CONCLUSIONS: We propose that the monocyte to lymphocyte ratio, which is easily derived from routine full differential blood counts, reflects an individual's capacity to mount an effective immune response to P. falciparum infection
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