1,074 research outputs found

    Composition of the Solar Interior: Information from Isotope Ratios

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    Measurements are reviewed showing that the interior of the Sun, the inner planets, and ordinary meteorites consist mostly of the same elements: Iron, oxygen, nickel, silicon, magnesium, sulfur and calcium. These results do not support the standard solar model.Comment: 4 pages, includes 6 figures, 1 Table, 39 references, 2002 SOHO 12/ GONG + 2002 Conference on Local and Global Helioseismology: The Present and Future, Big Bear Lake, C

    The battle for COVID-19 vaccines highlights the need for a new global governance mechanism

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    To the Editor—Although the rapid development of several vaccines against COVID-19 is an unparalleled scientific accomplishment, one made possible through the collaboration of researchers, industry and funding bodies, the absence of a system that secures equitable access to vaccines has uncovered deep fissures in the global governance systems for health, as noted in a recent Nature Medicine Editorial. For example, advance purchase agreements for vaccines against COVID-19 have favored affluent countries, allowing them to secure 150–500% of their predicted needs, while many citizens of low-and middle-income countries (LMICs) will remain unvaccinated until 2024. Additionally, the power of patent-holders and pharmaceutical companies to place conditions on the use of vaccines prices out access for LMICs, and bilateral purchasing deals are rarely disclosed. By affording priority on the basis of economic or political power, today’s discourse clearly deviates from previous ethical and public-health principles of maximizing lives or life-years saved, and the sentiment that “people’s entitlement to lifesaving resources should not depend on nationality”. The COVID-19 pandemic has tested wealthy nations’ commitments to Agenda 2030 and to ‘leaving no one behind’ at the same time that it has revealed democratic deficits, institutional rigidity, weak accountability systems, and inadequate policy space that protects health-governance systems from economic goals. Thus, the as-yet-limited support for the vaccine-sharing and allocation principles of the COVAX initiative may be a sign not only of a moral catastrophe, to quote the director-general of the World Health Organization (WHO), but also of inadequate global accountability mechanisms that exposes the consequences of commercial determinants of health

    Mindfulness meditation in the treatment of substance use disorders and preventing future relapse: neurocognitive mechanisms and clinical implications

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    Substance use disorders (SUDs) are a pervasive public health problem with deleterious consequences for individuals, families, and society. Furthermore, SUD intervention is complicated by the continuous possibility of relapse. Despite decades of research, SUD relapse rates remain high, underscoring the need for more effective treatments. Scientific findings indicate that SUDs are driven by dysregulation of neural processes underlying reward learning and executive functioning. Emerging evidence suggests that mindfulness training can target these neurocognitive mechanisms to produce significant therapeutic effects on SUDs and prevent relapse. The purpose of this manuscript is to review the cognitive, affective, and neural mechanisms underlying the effects of mindfulness-based interventions (MBIs) on SUDs. We discuss the etiology of addiction and neurocognitive processes related to the development and maintenance of SUDs. We then explore evidence supporting use of MBIs for intervening in SUDs and preventing relapse. Finally, we provide clinical recommendations about how these therapeutic mechanisms might be applied to intervening in SUDs and preventing relapse.National Institute of Health (NIH) award to ELG (R01DA042033

    A cost-effective method to quantify biological surface sediment reworking

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    We propose a simple and inexpensive method to determine the rate and pattern of surface sediment reworking by benthic organisms. Unlike many existing methods commonly used in bioturbation studies, which usually require sediment sampling, our approach is fully non-destructive and is well suited for investigating non-cohesive fine sediments in streams and rivers. Optical tracer (e.g., luminophores or coloured sand) disappearance or appearance is assessed through time based on optical quantification of surfaces occupied by tracers. Data are used to calculate surface sediment reworking (SSR) coefficients depicting bioturbation intensities. Using this method, we evaluated reworking activity of stream organisms (three benthic invertebrates and a fish) in laboratory microcosms mimicking pool habitats or directly in the field within arenas set in depositional zones. Our method was sensitive enough to measure SSR as low as 0.2 cm2.d-1, such as triggered by intermediate density (774 m-2) of Gammarus fossarum (Amphipoda) in microcosms. In contrast, complex invertebrate community in the field and a fish (Barbatula barabatula) in laboratory microcosms were found to yield to excessively high SSR (>60 cm2.d-1). Lastly, we suggest that images acquired during experiments can be used for qualitative evaluation of species-specific effects on sediment distribution

    Signal and Backgrounds for Leptoquarks at the LHC

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    We study the potentiality of the CERN Large Hadron Collider (LHC) to unravel the existence of first generation scalar leptoquarks. Working with the most general SU(2)LU(1)YSU(2)_L \otimes U(1)_Y invariant leptoquark interactions, we analyze in detail the signals and backgrounds that lead to a final state containing a pair e+ee^+e^- and jets. Our results indicate that a machine like the LHC will be able to discover leptoquarks with masses up to 2--3 TeV depending on their couplings.Comment: 37 pages, revtex, uses epsfig.sty (included), 15 figures (included

    Signal and Backgrounds for Leptoquarks at the LHC II: Vector Leptoquarks

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    We perform a detailed analyses of the CERN Large Hadron Collider (LHC) capability to discover first generation vector leptoquarks through their pair production. We study the leptoquark signals and backgrounds that give rise to final states containing a pair e+e- and jets. Our results show that the LHC will be able to discover vector leptoquarks with masses up to 1.3-2.1 TeV depending on their couplings to fermions and gluons.Comment: 18 pages, 3 figures, REVTe

    Signal and Backgrounds for the Single Production of Scalar and Vector Leptoquarks at the LHC

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    We perform a detailed analysis of the potentiality of the CERN Large Hadron Collider to study the single production of leptoquarks via ppe±qpp \to e^\pm q\to leptoquark e±q\to e^\pm q, with e±e^\pm generated by the splitting of photons radiated by the protons. Working with the most general SU(2)LU(1)YSU(2)_L \otimes U(1)_Y invariant effective lagrangian for scalar and vector leptoquarks, we analyze in detail the leptoquark signals and backgrounds that lead to a final state containing an e±e^\pm and a hard jet with approximately balanced transverse momenta. Our results indicate that the LHC will be able to discover leptoquarks with masses up to 2--3 TeV, depending on their type, for Yukawa couplings of the order of the electromagnetic one.Comment: Revtex, 23 pages, 11 postscript files. Uses axodraw.sty (included) and epsfig.sty. Typos corrected. To be published in Phys. Rev.
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