1,164 research outputs found

    A High-resolution Scintillating Fiber Tracker With Silicon Photomultiplier Array Readout

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    We present prototype modules for a tracking detector consisting of multiple layers of 0.25 mm diameter scintillating fibers that are read out by linear arrays of silicon photomultipliers. The module production process is described and measurements of the key properties for both the fibers and the readout devices are shown. Five modules have been subjected to a 12 GeV/c proton/pion testbeam at CERN. A spatial resolution of 0.05 mm and light yields exceeding 20 detected photons per minimum ionizing particle have been achieved, at a tracking efficiency of more than 98.5%. Possible techniques for further improvement of the spatial resolution are discussed.Comment: 31 pages, 27 figures, pre-print version of an article published in Nuclear Instruments and Methods in Physics Research Section A, Vol. 62

    Heterozygosity-fitness correlations in a wild mammal population: accounting for parental and environmental effects

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    HFCs (heterozygosity–fitness correlations) measure the direct relationship between an individual's genetic diversity and fitness. The effects of parental heterozygosity and the environment on HFCs are currently under-researched. We investigated these in a high-density U.K. population of European badgers (Meles meles), using a multimodel capture–mark–recapture framework and 35 microsatellite loci. We detected interannual variation in first-year, but not adult, survival probability. Adult females had higher annual survival probabilities than adult males. Cubs with more heterozygous fathers had higher first-year survival, but only in wetter summers; there was no relationship with individual or maternal heterozygosity. Moist soil conditions enhance badger food supply (earthworms), improving survival. In dryer years, higher indiscriminate mortality rates appear to mask differential heterozygosity-related survival effects. This paternal interaction was significant in the most supported model; however, the model-averaged estimate had a relative importance of 0.50 and overlapped zero slightly. First-year survival probabilities were not correlated with the inbreeding coefficient (f); however, small sample sizes limited the power to detect inbreeding depression. Correlations between individual heterozygosity and inbreeding were weak, in line with published meta-analyses showing that HFCs tend to be weak. We found support for general rather than local heterozygosity effects on first-year survival probability, and g2 indicated that our markers had power to detect inbreeding. We emphasize the importance of assessing how environmental stressors can influence the magnitude and direction of HFCs and of considering how parental genetic diversity can affect fitness-related traits, which could play an important role in the evolution of mate choice

    Lethal Injection, Politics, and the Future of the Death Penalty

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    “Welcome and Keynote:” Stephen Bright, Harvey Karp Visiting Lecturer at Yale Law School, and President and Senior Counsel with the Southern Center for Human Rights. (9:00 a.m. - 9:45 a.m.) “The Death Penalty Today: Lethal Injection Issues:” Panel 1 featured Deborah W. Denno, Arthur A. McGivney Professor of Law at Fordham University School of Law; Joel Zivot, Assistant Professor of Anesthesiology and Surgery at Emory University School of Medicine, and Medical Director of the Cardiothoracic Intensive Care Unit at Emory University Hospital; Eric Berger, Associate Professor of Law at Nebraska College of Law; and Frank Green, Reporter for the Richmond Times-Dispatch. Jim Gibson, Associate Dean for Student Affairs and Professor of Law at the University of Richmond School of Law, served as moderator. (10:00 a.m. -11:30 a.m.) “The Shifting Politics of the Death Penalty:” Panel 2 featured Mark Earley, former Attorney General of Virginia; Richard B. Roper, Partner with Thompson & Knight LLP, Corinna Barrett Lain, Associate Dean for Faculty Development and Professor of Law at the University of Richmond School of Law; and Stephen Smith, Professor of Law at Notre Dame Law School. Henry L. Chambers, Professor of Law at the University of Richmond School of Law, served as moderator. (1:00 p.m. - 2:30 p.m.) “The Future of the Death Penalty:” Panel 3 featured John Douglass, Professor of Law at the University of Richmond School of Law; Brandon L. Garrett, Professor of Law at the University of Virginia School of Law; and Richard Dieter, Executive Director of the Death Penalty Information Center. Mary Kelly Tate, Professor of Law at the University of Richmond School of Law, served as moderator. (2:45 p.m. - 4:15 p.m.

    Modelling the impact of intermittent preventive treatment for malaria on selection pressure for drug resistance

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    BACKGROUND: Intermittent preventive treatment (IPT) is a promising intervention for malaria control, although there are concerns about its impact on drug resistance. METHODS: The key model inputs are age-specific values for a) baseline anti-malarial dosing rate, b) parasite prevalence, and c) proportion of those treated with anti-malarials (outside IPT) who are infected. These are used to estimate the immediate effect of IPT on the genetic coefficient of selection (s). The scenarios modelled were year round IPT to infants in rural southern Tanzania, and three doses at monthly intervals of seasonal IPT in Senegal. RESULTS: In the simulated Tanzanian setting, the model suggests a high selection pressure for drug resistance, but that IPTi would only increase this by a small amount (4.4%). The percent change in s is larger if parasites are more concentrated in infants, or if baseline drug dosing is less common or less specific. If children aged up to five years are included in the Tanzanian scenario then the predicted increase in s rises to 31%. The Senegalese seasonal IPT scenario, in children up to five years, results in a predicted increase in s of 16%. CONCLUSION: There is a risk that the useful life of drugs will be shortened if IPT is implemented over a wide childhood age range. On the other hand, IPT delivered only to infants is unlikely to appreciably shorten the useful life of the drug used

    Progression of SARS-CoV-2 seroprevalence in St. Louis, Missouri, through January 2021

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    Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seropositivity was assessed for 3,066 individuals visiting hospitals in St. Louis, Missouri, during July 2020, November 2020, or January 2021. Seropositivity in children increased from 5.22% in July to 21.16% in January. In the same time frame, seropositivity among adults increased from 4.52% to 19.03%, prior to initiation of mass vaccination

    Overcoming the Challenges Associated with Image-based Mapping of Small Bodies in Preparation for the OSIRIS-REx Mission to (101955) Bennu

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    The OSIRIS-REx Asteroid Sample Return Mission is the third mission in NASA's New Frontiers Program and is the first U.S. mission to return samples from an asteroid to Earth. The most important decision ahead of the OSIRIS-REx team is the selection of a prime sample-site on the surface of asteroid (101955) Bennu. Mission success hinges on identifying a site that is safe and has regolith that can readily be ingested by the spacecraft's sampling mechanism. To inform this mission-critical decision, the surface of Bennu is mapped using the OSIRIS-REx Camera Suite and the images are used to develop several foundational data products. Acquiring the necessary inputs to these data products requires observational strategies that are defined specifically to overcome the challenges associated with mapping a small irregular body. We present these strategies in the context of assessing candidate sample-sites at Bennu according to a framework of decisions regarding the relative safety, sampleability, and scientific value across the asteroid's surface. To create data products that aid these assessments, we describe the best practices developed by the OSIRIS-REx team for image-based mapping of irregular small bodies. We emphasize the importance of using 3D shape models and the ability to work in body-fixed rectangular coordinates when dealing with planetary surfaces that cannot be uniquely addressed by body-fixed latitude and longitude.Comment: 31 pages, 10 figures, 2 table
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