2,003 research outputs found

    A global synthesis reveals biodiversity-mediated benefits for crop production

    Get PDF
    Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield-related ecosystem services can be maintained by a few dominant species or rely on high richness remains unclear. Using a global database from 89 studies (with 1475 locations), we partition the relative importance of species richness, abundance, and dominance for pollination; biological pest control; and final yields in the context of ongoing land-use change. Pollinator and enemy richness directly supported ecosystem services in addition to and independent of abundance and dominance. Up to 50% of the negative effects of landscape simplification on ecosystem services was due to richness losses of service-providing organisms, with negative consequences for crop yields. Maintaining the biodiversity of ecosystem service providers is therefore vital to sustain the flow of key agroecosystem benefits to society. [Abstract copyright: Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).

    Effectiveness, cost-effectiveness and cost-benefit of a single annual professional intervention for the prevention of childhood dental caries in a remote rural Indigenous community

    Get PDF
    Background The aim of the study is to reduce the high prevalence of tooth decay in children in a remote, rural Indigenous community in Australia, by application of a single annual dental preventive intervention. The study seeks to (1) assess the effectiveness of an annual oral health preventive intervention in slowing the incidence of dental caries in children in this community, (2) identify the mediating role of known risk factors for dental caries and (3) assess the cost-effectiveness and cost-benefit of the intervention. Methods/design The intervention is novel in that most dental preventive interventions require regular re-application, which is not possible in resource constrained communities. While tooth decay is preventable, self-care and healthy habits are lacking in these communities, placing more emphasis on health services to deliver an effective dental preventive intervention. Importantly, the study will assess cost-benefit and cost-effectiveness for broader implementation across similar communities in Australia and internationally. Discussion There is an urgent need to reduce the burden of dental decay in these communities, by implementing effective, cost-effective, feasible and sustainable dental prevention programs. Expected outcomes of this study include improved oral and general health of children within the community; an understanding of the costs associated with the intervention provided, and its comparison with the costs of allowing new lesions to develop, with associated treatment costs. Findings should be generalisable to similar communities around the world. The research is registered with the Australian New Zealand Clinical Trials Registry (ANZCTR), registration number ACTRN12615000693527; date of registration: 3rd July 2015

    The future of pediatric dentistry education and curricula : A Chilean perspective

    Get PDF
    Publisher Copyright: © 2016 The Author(s). Copyright: Copyright 2016 Elsevier B.V., All rights reserved.Background: A meeting was organised to consolidate a network of researchers and academics from Australia, Brazil, Chile, the UK and the USA, relating to Early Childhood Caries (ECC) and Dental Trauma (DT). As part of this meeting, a dedicated session was held on the future of paediatric dental education and curricula. Twenty-four paediatric dentistry (PD) academics, representing eight Chilean dental schools, and three international specialists (from Brazil and Latvia) participated in group discussions facilitated by five members of the ECC/DT International Collaborative Network. Data were collected from group discussions which followed themes developed as guides to identify key issues associated with paediatric dentistry education, training and research. Discussion: Participants discussed current PD dental curricula in Chile, experiences in educating new cohorts of oral health care providers, and the outcomes of existing efforts in education and research in PD. They also, identified challenges, opportunities and areas in need of further development. Summary: This paper provides an introspective analysis of the education and training of PD in Chile; describes the input provided by participants into pediatric dentistry education and curricula; and sets out some key priorities for action with suggested directions to best prepare the future dental workforce to maximise oral health outcomes for children. Immediate priorities for action in paediatric dentistry in Chile were proposed.publishersversionPeer reviewe

    Effects of boundary conditions on magnetization switching in kinetic Ising models of nanoscale ferromagnets

    Full text link
    Magnetization switching in highly anisotropic single-domain ferromagnets has been previously shown to be qualitatively described by the droplet theory of metastable decay and simulations of two-dimensional kinetic Ising systems with periodic boundary conditions. In this article we consider the effects of boundary conditions on the switching phenomena. A rich range of behaviors is predicted by droplet theory: the specific mechanism by which switching occurs depends on the structure of the boundary, the particle size, the temperature, and the strength of the applied field. The theory predicts the existence of a peak in the switching field as a function of system size in both systems with periodic boundary conditions and in systems with boundaries. The size of the peak is strongly dependent on the boundary effects. It is generally reduced by open boundary conditions, and in some cases it disappears if the boundaries are too favorable towards nucleation. However, we also demonstrate conditions under which the peak remains discernible. This peak arises as a purely dynamic effect and is not related to the possible existence of multiple domains. We illustrate the predictions of droplet theory by Monte Carlo simulations of two-dimensional Ising systems with various system shapes and boundary conditions.Comment: RevTex, 48 pages, 13 figure

    Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

    Get PDF
    This paper presents measurements of the W+μ+νW^+ \rightarrow \mu^+\nu and WμνW^- \rightarrow \mu^-\nu cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

    Opportunistic illnesses in Brazilian children with AIDS: results from two national cohort studies, 1983-2007

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>HAART has significantly reduced AIDS-related morbidity in children. However, limited evidence is available from developing countries regarding patterns of opportunistic illnesses. We describe these events and their associated factors in children with AIDS in Brazil.</p> <p>Methods</p> <p>This study is based on two representative retrospective multi-center cohorts including a total 1,859 children with AIDS, infected via mother-to-child transmission (MTCT), between 1983-2002. Opportunistic illnesses were described and analyzed over time. The association of demographic, clinical and operational data with the occurrence of opportunistic diseases was assessed.</p> <p>Results</p> <p>In total, 1,218 (65.5%) had at least one event of an opportunistic disease. Variables significantly associated with occurrence of these events included: region of residence (OR 2.68-11.33, as compared to the Northern region), age < 1 year at diagnosis (OR 2.56, 95% CI 1.81-3.61, p < 0.001), and non-performance of MTCT prevention measures (OR 1.58, 95% CI 1.21-2.07, p < 0.001). Protective factors included year of HIV diagnosis in the HAART era (OR 0.34, 95% CI 0.15-0.76, p = 0.009) and ART use (OR 0.58, 95% CI 0.44-0.77, p < 0.001). In both periods bacterial infections represented the most common opportunistic events (58.6 vs. 34.7%; p < 0.001), followed by <it>Pneumocystis jirovecii </it>pneumonia (21.9 vs. 13.2%; p < 0.001), and bacterial meningitis/sepsis (16.8 vs. 7.4%; p < 0.001).</p> <p>Conclusions</p> <p>Despite the significant reduction in recent years, opportunistic illnesses are still common in Brazilian children with AIDS in the HAART era, especially bacterial diseases. The data reinforce the need for scaling up prevention of MTCT, early diagnosis of infection, and improvement of comprehensive pediatric care.</p

    Search for direct stau production in events with two hadronic tau-leptons in root s=13 TeV pp collisions with the ATLAS detector

    Get PDF
    A search for the direct production of the supersymmetric partners ofτ-leptons (staus) in final stateswith two hadronically decayingτ-leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of139fb−1, recorded with the ATLAS detector at the LargeHadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected StandardModel background is observed. Limits are derived in scenarios of direct production of stau pairs with eachstau decaying into the stable lightest neutralino and oneτ-lepton in simplified models where the two staumass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidencelevel for a massless lightest neutralino

    Measurement of χ c1 and χ c2 production with s√ = 7 TeV pp collisions at ATLAS

    Get PDF
    The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at s√ = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χ c states are reconstructed through the radiative decay χ c → J/ψγ (with J/ψ → μ + μ −) where photons are reconstructed from γ → e + e − conversions. The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum. The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays. The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured

    Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

    Get PDF
    A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV

    Measurement of the production of a W boson in association with a charm quark in pp collisions at √s = 7 TeV with the ATLAS detector

    Get PDF
    The production of a W boson in association with a single charm quark is studied using 4.6 fb−1 of pp collision data at s√ = 7 TeV collected with the ATLAS detector at the Large Hadron Collider. In events in which a W boson decays to an electron or muon, the charm quark is tagged either by its semileptonic decay to a muon or by the presence of a charmed meson. The integrated and differential cross sections as a function of the pseudorapidity of the lepton from the W-boson decay are measured. Results are compared to the predictions of next-to-leading-order QCD calculations obtained from various parton distribution function parameterisations. The ratio of the strange-to-down sea-quark distributions is determined to be 0.96+0.26−0.30 at Q 2 = 1.9 GeV2, which supports the hypothesis of an SU(3)-symmetric composition of the light-quark sea. Additionally, the cross-section ratio σ(W + +c¯¯)/σ(W − + c) is compared to the predictions obtained using parton distribution function parameterisations with different assumptions about the s−s¯¯¯ quark asymmetry
    corecore