988 research outputs found

    Intraoperative contrast-enhanced sonography of bowel blood flow: preliminary experience

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    The potential to predict, and therefore avoid, anastomotic failure has eluded generations of colon and rectal surgeons to date. A reliable, reproducible method of assessing bowel blood flow therefore would be of enormous potential clinical relevance. To our knowledge, intraoperative contrast-enhanced sonography of the bowel has not been performed previously. We present our study assessing the feasibility of using contrast-enhanced sonography to study bowel perfusion intraoperatively. We studied 8 patients (4 male and 4 female) with an age range of 52 to 81 years who underwent colorectal surgery (right hemicolectomies, n = 3; Hartmann procedure, n = 1; anterior resections, n = 2; and bowel resections with ileocolic anastomoses, n = 2). A 5-mL bolus of a sulfur hexafluoride contrast agent solution was injected before and after vascular ligation with simultaneous noncompression ultrasound scanning directly over the large bowel. The patients were followed clinically to assess for leaks. Contrast-enhanced sonographic time-intensity curves were generated for the time to peak and maximum amplitude. Moderate interobserver agreement was shown for the time to peak (Īŗ = 0.50) and maximum amplitude (Īŗ = 0.42), and moderate intraobserver agreement was shown for the time to peak (Īŗ= 0.53) and maximum amplitude (Īŗ= 0.53). No significant differences were shown between the time to peak (P = .28) and maximum amplitude (P = .49) for the preligation and postligation scans. To our knowledge, intraoperative contrast-enhanced sonography of the bowel has not been performed previously. We have shown the technique to be feasible with good intraobserver and interobserver agreement. Further work is ongoing to optimize the technique and assess its use in predicting anastomotic breakdown.published_or_final_versio

    Orogenic-orographic feedback and the rise of the Central Andes

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    The rise of large mountain ranges is considered to be driven by tectonics potentially coupled with climate driven-erosion, although the role of this coupling remains uncertain. The arid climate of the Central Andes allows us to strengthen our understanding of the relative roles of these processes in mountain range development globally. Here we compile estimates of exhumation, sedimentation, aridity and surface uplift across the Central Andes for the last 50 Ma. We aim to place constraints on the relative timing of rock uplift (displacement of rocks with respect to the geoid), exhumation (displacement of rocks with respect to the surface) and surface uplift (displacement of the earth's surface with respect to the geoid). We show that initial rock uplift of the Andes extends back at least 50 Myr. This rock uplift generated orographically driven precipitation on windward slopes leading to increased exhumation but limited preservation of surface uplift. Eastward propagation of the mountain range resulted in increasingly extreme orographic effects on the leeward side amplifying aridity, reducing exhumation and increasing preservation of surface uplift. Essentially, surface uplift shows a āˆ¼5-10 Myr lag behind initial rock uplift as the Andes grow asymmetrically through time. We suggest that an eastward propagating pattern of exhumation, aridity and surface uplift with time, reconciles previous contradictory models of Andean uplift. One Sentence Summary: Uplift of the Central Andes is reconstructed over the last 50 Myr and the precise relationship between roles of tectonics and climate established

    Using spatial patterns of fluvial incision to constrain continental-scale uplift in the Andes

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    This study was funded by BHP and the University of Brighton Rising Stars. The authors are grateful to Marit Van Zalinge and Masie Mather for discussions on the manuscript.Peer reviewedPostprin

    The role of rewilding in mitigating hydrological extremes: State of the evidence

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    Landscape rewilding has the potential to help mitigate hydrological extremes by allowing natural processes to function. Our systematic review assessed the evidence base for rewilding-driven mitigation of high and low flows. The review uncovers a lack of research directly addressing rewilding, but highlights research in analogue contexts which can, with caution, indicate the nature of change. There is a lack of before-after studies that enable deeper examination of temporal trajectories and legacy effects, and a lack of research on the scrub and shrubland habitats common in rewilding projects. Over twice as much evidence is available for high flows compared to low flows, and fewer than one third of studies address high and low flows simultaneously, limiting our understanding of co-benefits and contrasting effects. Flow magnitude variables are better represented within the literature than flow timing variables, and there is greater emphasis on modeling for high flows, and on direct measurement for low flows. Most high flow studies report a mitigating effect, but with variability in the magnitude of effect, and some exceptions. The nature of change for low flows is more complex and suggests a higher potential for increased low flow risks associated with certain trajectories but is based on a very narrow evidence base. We recommend that future research aims to: capture effects on both high and low flow extremes for a given type of change; analyze both magnitude and timing characteristics of flow extremes; and examine temporal trajectories (before and after data) ideally using a full before-after-control-impact design. This article is categorized under: Human Water > Value of Water Science of Water > Hydrological Processes Science of Water > Water Extremes Water and Life > Conservation, Management, and Awareness

    Aquatic Hemiptera in Southwest Cameroon: Biodiversity of Potential Reservoirs of Mycobacterium ulcerans and multiple wolbachia sequence types revealed by metagenomics

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    Buruli ulcer (BU), caused by Mycobacterium ulcerans, is a neglected tropical disease associated with freshwater habitats. A variety of limnic organisms harbor this pathogen, including aquatic bugs (Hemiptera: Heteroptera), which have been hypothesized to be epidemiologically important reservoirs. Aquatic Hemiptera exhibit high levels of diversity in the tropics, but species identification remains challenging. In this study, we collected aquatic bugs from emerging foci of BU in the Southwest Region of Cameroon, which were identified using morphological and molecular methods. The bugs were screened for mycobacterial DNA and a selection of 20 mycobacteria-positive specimens from the families Gerridae and Veliidae were subjected to next-generation sequencing. Only one individual revealed putative M. ulcerans DNA, but all specimens contained sequences from the widespread alphaproteobacterial symbiont, Wolbachia. Phylogenetic analysis placed the Wolbachia sequences into supergroups A, B, and F. Circularized mitogenomes were obtained for seven gerrids and two veliids, the first from these families for the African continent. This study suggests that aquatic Hemiptera may have a minor role (if any) in the spread of BU in Southwest Cameroon. Our metagenomic analysis provides new insights into the incursion of Wolbachia into aquatic environments and generated valuable resources to aid molecular taxonomic studies of aquatic Hemiptera. Ā© 2019 by the authors

    Evaluation of Risk-based Re-Authentication Methods

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    Risk-based Authentication (RBA) is an adaptive security measure that improves the security of password-based authentication by protecting against credential stuffing, password guessing, or phishing attacks. RBA monitors extra features during login and requests for an additional authentication step if the observed feature values deviate from the usual ones in the login history. In state-of-the-art RBA re-authentication deployments, users receive an email with a numerical code in its body, which must be entered on the online service. Although this procedure has a major impact on RBA's time exposure and usability, these aspects were not studied so far. We introduce two RBA re-authentication variants supplementing the de facto standard with a link-based and another code-based approach. Then, we present the results of a between-group study (N=592) to evaluate these three approaches. Our observations show with significant results that there is potential to speed up the RBA re-authentication process without reducing neither its security properties nor its security perception. The link-based re-authentication via "magic links", however, makes users significantly more anxious than the code-based approaches when perceived for the first time. Our evaluations underline the fact that RBA re-authentication is not a uniform procedure. We summarize our findings and provide recommendations.Comment: 14 pages, 5 figures. Paper accepted for IFIP SEC 2020. Keywords: Risk-based Authentication (RBA), Re-authentication, Usable Securit

    Geomorphology on geologic timescales: Evolution of the late Cenozoic Pacific paleosurface in Northern Chile and Southern Peru

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    publisher: Elsevier articletitle: Geomorphology on geologic timescales: Evolution of the late Cenozoic Pacific paleosurface in Northern Chile and Southern Peru journaltitle: Earth-Science Reviews articlelink: http://dx.doi.org/10.1016/j.earscirev.2017.04.004 content_type: article copyright: Ā© 2017 Elsevier B.V. All rights reserved

    JULES-GL7: The Global Land configuration of the Joint UK Land Environment Simulator version 7.0 and 7.2

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    This is the final version. Available on open access from the European Geosciences Union via the DOI in this recordData availability. The model configuration and associated forcing data are available via the indicated methods in the manuscript (see Appendix A). JULES and associated configurations are freely available for non-commercial research use as set out in the JULES user terms and conditions (http://jules-lsm.github.io/access_req/JULES_Licence.pdf, last access: 31 January 2020).Code availability. This work is based on JULES version 5.3 with specific configurations included in the form of suites. For full information regarding accessing the code and configurations, please refer to Appendix A.We present the latest global land configuration of the Joint UK Land Environment Simulator (JULES) model as used in the latest international Coupled Model Intercomparison Project (CMIP6). The configuration is defined by the combination of switches, parameter values and ancillary data, which we provide alongside a set of historical forcing data that defines the experimental setup. The configurations provided are JULES-GL7.0, the base setup used in CMIP6 and JULES-GL7.2, a subversion that includes improvements to the representation of canopy radiation and interception. These configurations are recommended for all JULES applications focused on the exchange and state of heat, water and momentum at the land surface. In addition, we provide a standardised modelling system that runs on the Natural Environment Research Council (NERC) JASMIN cluster, accessible to all JULES users. This is provided so that users can test and evaluate their own science against the standard configuration to promote community engagement in the development of land surface modelling capability through JULES. It is intended that JULES configurations should be independent of the underlying code base, and thus they will be available in the latest release of the JULES code. This means that different code releases will produce scientifically comparable results for a given configuration version. Versioning is therefore determined by the configuration as opposed to the underlying code base.BEIS and DEFRA Met Office Hadley Centre Climate ProgrammeEuropean Union Horizon 202
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