2,232 research outputs found

    Two \u3ci\u3eEntomophthora\u3c/i\u3e Species Associated with Disease Epizootics of the Alfalfa Weevil, \u3ci\u3eHypera Postica\u3c/i\u3e (Coleoptera: Curculionidae), in Ontario

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    Recent studies have shown that disease epizootics in Ontario populations of the alfalfa weevil, Hypera postica (Gyllenhal), are caused by a complex of two fungi

    Tuning biexciton binding and anti-binding in core/shell quantum dots

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    We use a path integral quantum Monte Carlo method to simulate excitons and biexcitons in core shell nanocrystals with Type-I, II and quasi-Type II band alignments. Quantum Monte Carlo techniques allow for all quantum correlations to be included when determining the thermal ground state, thus producing accurate predictions of biexciton binding. These subtle quantum correlations are found to cause the biexciton to be binding with Type-I carrier localization and strongly anti-binding with Type-II carrier localization, in agreement with experiment for both core shell nanocrystals and dot in rod nanocrystal structures. Simple treatments based on perturbative approaches are shown to miss this important transition in the biexciton binding. Understanding these correlations offers prospects to engineer strong biexciton anti-binding which is crucial to the design of nanocrystals for single exciton lasing applications.Comment: 10 pages, 11 figure

    Optical carrier wave shocking: detection and dispersion

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    Carrier wave shocking is studied using the Pseudo-Spectral Spatial Domain (PSSD) technique. We describe the shock detection diagnostics necessary for this numerical study, and verify them against theoretical shocking predictions for the dispersionless case. These predictions show Carrier Envelope Phase (CEP) and pulse bandwidth sensitivity in the single-cycle regime. The flexible dispersion management offered by PSSD enables us to independently control the linear and nonlinear dispersion. Customized dispersion profiles allow us to analyze the development of both carrier self-steepening and shocks. The results exhibit a marked asymmetry between normal and anomalous dispersion, both in the limits of the shocking regime and in the (near) shocked pulse waveforms. Combining these insights, we offer some suggestions on how carrier shocking (or at least extreme self-steepening) might be realised experimentally.Comment: 9 page

    Pearling: stroke segmentation with crusted pearl strings

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    We introduce a novel segmentation technique, called Pearling, for the semi-automatic extraction of idealized models of networks of strokes (variable width curves) in images. These networks may for example represent roads in an aerial photograph, vessels in a medical scan, or strokes in a drawing. The operator seeds the process by selecting representative areas of good (stroke interior) and bad colors. Then, the operator may either provide a rough trace through a particular path in the stroke graph or simply pick a starting point (seed) on a stroke and a direction of growth. Pearling computes in realtime the centerlines of the strokes, the bifurcations, and the thickness function along each stroke, hence producing a purified medial axis transform of a desired portion of the stroke graph. No prior segmentation or thresholding is required. Simple gestures may be used to trim or extend the selection or to add branches. The realtime performance and reliability of Pearling results from a novel disk-sampling approach, which traces the strokes by optimizing the positions and radii of a discrete series of disks (pearls) along the stroke. A continuous model is defined through subdivision. By design, the idealized pearl string model is slightly wider than necessary to ensure that it contains the stroke boundary. A narrower core model that fits inside the stroke is computed simultaneously. The difference between the pearl string and its core contains the boundary of the stroke and may be used to capture, compress, visualize, or analyze the raw image data along the stroke boundary

    High urinary tungsten concentration is associated with stroke in the National Health and Nutrition Examination Survey 1999-2010.

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    Published onlineClinical TrialMulticenter StudyResearch Support, Non-U.S. Gov'tBACKGROUND: In recent years there has been an exponential increase in tungsten demand, potentially increasing human exposure to the metal. Currently, the toxicology of tungsten is poorly understood, but mounting evidence suggests that both the elemental metal and its alloys have cytotoxic effects. Here, we investigate the association between tungsten and cardiovascular disease (CVD) or stroke using six waves of the National Health and Nutrition Examination Survey (NHANES). METHODS: We investigated associations using crude and adjusted logistic regression models in a cohort of 8614 adults (18-74 years) with 193 reported stroke diagnoses and 428 reported diagnoses of CVD. We also stratified our data to characterize associations in a subset of younger individuals (18-50 years). RESULTS: Elevated tungsten concentrations were strongly associated with an increase in the prevalence of stroke, independent of typical risk factors (Odds Ratio (OR): 1.66, 95% Confidence Interval (95% CI): 1.17, 2.34). The association between tungsten and stroke in the young age category was still evident (OR: 2.17, 95% CI: 1.33, 3.53). CONCLUSION: This study represents the most comprehensive analysis of the human health effects of tungsten to date. Individuals with higher urinary tungsten concentrations have double the odds of reported stroke. We hypothesize that the pathological pathway resulting from tungsten exposure may involve oxidative stress.This work was supported by funding from University of Exeter Medical School. No funding organization or sponsor played any part in the design or conduct of the study, in the analysis or interpretation of the data, or preparation, review, or approval of the manuscript. The European Centre for the Environment and Human Health (part of the University of Exeter Medical School) is supported by investment from the ERDF (European Regional Development Fund) and ESF (European Social Fund) Convergence Programmed for Cornwall and the Isles of Scilly. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

    Scholarly communication in transition: The use of question marks in the titles of scientific articles in medicine, life sciences and physics 1966–2005

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    The titles of scientific articles have a special significance. We examined nearly 20 million scientific articles and recorded the development of articles with a question mark at the end of their titles over the last 40 years. Our study was confined to the disciplines of physics, life sciences and medicine, where we found a significant increase from 50% to more than 200% in the number of articles with question-mark titles. We looked at the principle functions and structure of the titles of scientific papers, and we assume that marketing aspects are one of the decisive factors behind the growing usage of question-mark titles in scientific articles

    Local implicit modeling of blood vessels for interactive simulation

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    International audienceIn the context of computer-based simulation, contact management requires an accurate, smooth, but still efficient surface model for the blood vessels. A new implicit model is proposed, consisting of a tree of local implicit surfaces generated by skeletons ({\em blobby models}). The surface is reconstructed from data points by minimizing an energy, alternating with an original blob selection and subdivision scheme. The reconstructed models are very efficient for simulation and were shown to provide a sub-voxel approximation of the vessel surface on 5 patients

    Changes in poisonings among adolescents in the UK between 1992 and 2012: a population based cohort study

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    Background: Poisonings are a common cause of morbidity and mortality among adolescents. Yet surveillance data indicating current incidence rates (IRs) and time trends are lacking, making policy development and service planning difficult. We utilised population based primary care data to estimate adolescent poisoning rates according to intent across the UK. Methods: A cohort study of 1 311 021 adolescents aged 10–17 years, between 1992 and 2012, was conducted using routine primary care data from The Health Improvement Network. IRs and adjusted IRRs with 95% CIs were calculated for all poisonings, intentional, unintentional, unknown intent and alcohol related poisonings, by age, sex, calendar time and socioeconomic deprivation. Results: Overall poisoning incidence increased by 27% from the period 1992–1996 to 2007–2012, with the largest increases in intentional poisonings among females aged 16–17 years (IR 391.4/100 000 person years (PY), CI 328.9 to 465.7 for age 17 years in 1992–1996; 767.0/100 000 PY, CI 719.5 to 817.7 in 2007–2012) and alcohol related poisonings in females aged 15–16 years (IR 65.7/100 000 PY, CI 43.3 to 99.8 rising to 130.0/100 000 PY, CI 110.0 to 150.0 for age 15 years). A strong socioeconomic gradient for all poisonings persisted over time, with higher rates among the more deprived (IRR 2.63, CI 2.41 to 2.88 for the most vs least deprived quintile in 2007–2012). Conclusions: Adolescent poisonings, especially intentional poisonings, have increased substantially over time and remain associated with health inequalities. Social and psychological support for adolescents should be targeted at more deprived communities, and child and adolescent mental health and alcohol support service provision should be commissioned to reflect the changing need

    Rapid Quantification of Molecular Diversity for Selective Database Acquisition

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    There is an increasing need to expand the structural diversity of the molecules investigated in lead-discovery programs. One way in which this can be achieved is by acquiring external datasets that will enhance an existing database. This paper describes a rapid procedure for the selection of external datasets using a measure of structural diversity that is calculated from sums of pairwise intermolecular structural similarities
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