421 research outputs found

    Flaring Rates and the Evolution of Sunspot Group McIntosh Classifications

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    Sunspot groups are the main source of solar flares, with the energy to power them being supplied by magnetic-field evolution (e.g. flux emergence or twisting/shearing). To date, few studies have investigated the statistical relation between sunspot-group evolution and flaring, with none considering evolution in the McIntosh classification scheme. Here we present a statistical analysis of sunspot groups from Solar Cycle 22, focusing on 24-hour changes in the three McIntosh classification components. Evolution-dependent > C1.0, >M1.0, and > X1.0 flaring rates are calculated, leading to the following results: (i) flaring rates become increasingly higher for greater degrees of upward evolution through the McIntosh classes, with the opposite found for downward evolution; (ii) the highest flaring rates are found for upward evolution from larger, more complex, classes (e.g. Zurich D- and E-classes evolving upward to F-class produce > C1.0 rates of 2.66 ± 0.28 and 2.31 ± 0.09 flares per 24 hours, respectively); (iii) increasingly complex classes give higher rates for all flare magnitudes, even when sunspot groups do not evolve over 24 hours. These results support the hypothesis that injection of magnetic energy by flux emergence (i.e. increasing in Zurich or compactness classes) leads to a higher frequency and magnitude of flaring

    Flare Forecasting Using the Evolution of McIntosh Sunspot Classifications

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    Most solar flares originate in sunspot groups, where magnetic field changes lead to energy build-up and release. However, few flare-forecasting methods use information of sunspot-group evolution, instead focusing on static point-in-time observations. Here, a new forecast method is presented based upon the 24-hr evolution in McIntosh classification of sunspot groups. Evolution-dependent >C1.0 and >M1.0 flaring rates are found from NOAA-numbered sunspot groups over December 1988 to June 1996 (Solar Cycle 22; SC22) before converting to probabilities assuming Poisson statistics. These flaring probabilities are used to generate operational forecasts for sunspot groups over July 1996 to December 2008 (SC23), with performance studied by verification metrics. Major findings are: i) considering Brier skill score (BSS) for >C1.0 flares, the evolution-dependent McIntosh-Poisson method BSS_evolution=0.09 performs better than the static McIntosh-Poisson method BSS_static= -0.09; ii) low BSS values arise partly from both methods over-forecasting SC23 flares from the SC22 rates, symptomatic of >C1.0 rates in SC23 being on average \approx80% of those in SC22 (with >M1.0 being approx 50%); iii) applying a bias-correction factor to reduce the SC22 rates used in forecasting SC23 flares yields modest improvement in skill relative to climatology for both methods BSS_corr_static = 0.09$ and BSS_corr_evolution = 0.20) and improved forecast reliability diagrams

    Flare Forecasting Using the Evolution of McIntosh Sunspot Classifications

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    Most solar flares originate in sunspot groups, where magnetic field changes lead to energy build-up and release. However, few flare-forecasting methods use information of sunspot-group evolution, instead focusing on static point-in-time observations. Here, a new forecast method is presented based upon the 24-hr evolution in McIntosh classification of sunspot groups. Evolution-dependent \geqslantC1.0 and \geqslantM1.0 flaring rates are found from NOAA-numbered sunspot groups over December 1988 to June 1996 (Solar Cycle 22; SC22) before converting to probabilities assuming Poisson statistics. These flaring probabilities are used to generate operational forecasts for sunspot groups over July 1996 to December 2008 (SC23), with performance studied by verification metrics. Major findings are: i) considering Brier skill score (BSS) for \geqslantC1.0 flares, the evolution-dependent McIntosh-Poisson method (BSSevolution=0.09\text{BSS}_{\text{evolution}}=0.09) performs better than the static McIntosh-Poisson method (BSSstatic=0.09\text{BSS}_{\text{static}} = -0.09); ii) low BSS values arise partly from both methods over-forecasting SC23 flares from the SC22 rates, symptomatic of \geqslantC1.0 rates in SC23 being on average \approx80% of those in SC22 (with \geqslantM1.0 being \approx50%); iii) applying a bias-correction factor to reduce the SC22 rates used in forecasting SC23 flares yields modest improvement in skill relative to climatology for both methods (BSSstaticcorr=0.09\mathrm{BSS}^{\mathrm{corr}}_{\mathrm{static}} = 0.09 and BSSevolutioncorr=0.20\mathrm{BSS}^{\mathrm{corr}}_{\mathrm{evolution}} = 0.20) and improved forecast reliability diagrams.Comment: 21 pages, 9 figure

    Cardiovascular disease risk in the offspring of diabetic women: the impact of the intrauterine environment

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    The incidence of gestational diabetes is increasing worldwide, exposing large numbers of infants to hyperglycaemia whilst in utero. This exposure may have a long-term negative impact on the cardiovascular health of the offspring. Novel methods to assess cardiovascular status in the neonatal period are now available—including measuring arterial intima-media thickness and retinal photography. These measures will allow researchers to assess the relative impact of intrauterine exposures, distinguishing these from genetic or postnatal environmental factors. Understanding the long-term impact of the intrauterine environment should allow the development of more effective health policy and interventions to decrease the future burden of cardiovascular disease. Initiating disease prevention aimed at the developing fetus during the antenatal period may optimise community health outcomes

    Identity dynamics as a barrier to organizational change

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    This article seeks to explore the construction of group and professional identities in situations of organizational change. It considers empirical material drawn from a health demonstration project funded by the Scottish Executive Health Department, and uses insights from this project to discuss issues that arise from identity construction(s) and organizational change. In the course of the project studied here, a new organizational form was developed which involved a network arrangement with a voluntary sector organization and the employment of “lay-workers” in what had traditionally been a professional setting. Our analysis of the way actors made sense of their identities reveals that characterizations of both self and other became barriers to the change process. These identity dynamics were significant in determining the way people interpreted and responded to change within this project and which may relate to other change-oriented situations

    Dynamic earthquake triggering response tracks evolving unrest at Sierra Negra volcano, Galápagos Islands

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    The propensity for dynamic earthquake triggering is thought to depend on the local stress state and amplitude of the stress perturbation. However, the nature of this dependency has not been confirmed within a single crustal volume. Here, we show that at Sierra Negra volcano, Galápagos Islands, the intensity of dynamically triggered earthquakes increased as inflation of a magma reservoir elevated the stress state. The perturbation of short-term seismicity within teleseismic surface waves also increased with peak dynamic strain. Following rapid coeruptive subsidence and reduction in stress and background seismicity rates, equivalent dynamic strains no longer triggered detectable seismicity. These findings offer direct constraints on the primary controls on dynamic triggering and suggest that the response to dynamic stresses may help constrain the evolution of volcanic unrest

    Rapid spread of Zika virus in the Americas: implications for public health preparedness for mass gatherings at the 2016 Brazil Olympic Games

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    Mass gatherings at major international sporting events put millions of international travelers and local host-country residents at risk of acquiring infectious diseases, including locally endemic infectious diseases. The mosquito-borne Zika virus (ZIKV) has recently aroused global attention due to its rapid spread since its first detection in May 2015 in Brazil to 22 other countries and other territories in the Americas. The ZIKV outbreak in Brazil, has also been associated with a significant rise in the number of babies born with microcephaly and neurological disorders, and has been declared a 'Global Emergency' by the World Health Organization. This explosive spread of ZIKV in Brazil poses challenges for public health preparedness and surveillance for the Olympics and Paralympics which are due to be held in Rio De Janeiro in August, 2016. We review the epidemiology and clinical features of the current ZIKV outbreak in Brazil, highlight knowledge gaps, and review the public health implications of the current ZIKV outbreak in the Americas. We highlight the urgent need for a coordinated collaborative response for prevention and spread of infectious diseases with epidemic potential at mass gatherings events. (C) 2016 The Authors. Published by Elsevier Ltd on behalf of International Society for Infectious Diseases
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