302 research outputs found

    On the reliability of multistate systems with imprecise probabilities

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    Розглядається обчислення надійності в складних системах за наявності випадкового набору оцінок працездатності елементів. Виявлено, що підхід Демпстер-Шефера є відповідним математичним інструментом, який відповідає поставленим задачам. Для випадку, коли взаємозалежності елементів невідомі, наведено також оцінки ефективності системи переконань і правдоподібність функції.Рассматривается вычисления надежности в сложных системах при наличии случайного набора оце- нок работоспособности элементов. Выявлено, что подход Демпстер-Шефера является соответствующим математическим инструментом, который соответствует поставленным задачам. Для случая, когда взаимозависимости элементов неизвестны, приведены также оценки эффективности системы убеждений и правдоподобность функции.We consider the computation of multistate systems reliabilities in the presence of random set estimations for the elements' working abilities. It turns out that the Dempster-Shafer approach is a suitable mathematical tool. For the case that the interdependence of the elements is unknown, bounds for the system's performance belief and plausibility functions are given as well

    ECSA's Characteristics of Citizen Science: Explanation Notes

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    This explanation document provides an interpretation of and explanation for the characteristics document, which was kept short to make it useful to different stakeholders. In this document, the characteristics document is represented, with the original text in blue and an explanation in black

    A Structural Model of the Pore-Forming Region of the Skeletal Muscle Ryanodine Receptor (RyR1)

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    Ryanodine receptors (RyRs) are ion channels that regulate muscle contraction by releasing calcium ions from intracellular stores into the cytoplasm. Mutations in skeletal muscle RyR (RyR1) give rise to congenital diseases such as central core disease. The absence of high-resolution structures of RyR1 has limited our understanding of channel function and disease mechanisms at the molecular level. Here, we report a structural model of the pore-forming region of RyR1. Molecular dynamics simulations show high ion binding to putative pore residues D4899, E4900, D4938, and D4945, which are experimentally known to be critical for channel conductance and selectivity. We also observe preferential localization of Ca2+ over K+ in the selectivity filter of RyR1. Simulations of RyR1-D4899Q mutant show a loss of preference to Ca2+ in the selectivity filter as seen experimentally. Electrophysiological experiments on a central core disease mutant, RyR1-G4898R, show constitutively open channels that conduct K+ but not Ca2+. Our simulations with G4898R likewise show a decrease in the preference of Ca2+ over K+ in the selectivity filter. Together, the computational and experimental results shed light on ion conductance and selectivity of RyR1 at an atomistic level

    Contours of Citizen Science: A Vignette Study

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    Citizen science has expanded rapidly over the past decades. Yet, defining citizen science and its boundaries remained a challenge, and this is reflected in the literature - for example in the proliferation of typologies and definitions. There is a need for identifying areas of agreement and disagreement within the citizen science practitioners community on what should be considered as citizen science activity. This paper describes the development and results of a survey that examined this issue, through the use of vignettes - short case descriptions that describe an activity, while asking the respondents to rate the activity on a scale from ‘not citizen science’ (0%) to ‘citizen science’ (100%). The survey included 50 vignettes, of which 5 were developed as clear cases of not-citizen science activities, 5 as widely accepted citizen science activities, and the others addressing 10 factors and 61 sub-factors that can lead to controversy about an activity. The survey has attracted 333 respondents, who provided over 5,100 ratings. The analysis demonstrates the plurality of understanding of what citizen science is and calls for an open understanding of what activities are included in the field

    Life expectancy associated with different ages at diagnosis of type 2 diabetes in high-income countries: 23 million person-years of observation

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    Background: The prevalence of type 2 diabetes is increasing rapidly, particularly among younger age groups. Estimates suggest that people with diabetes die, on average, 6 years earlier than people without diabetes. We aimed to provide reliable estimates of the associations between age at diagnosis of diabetes and all-cause mortality, cause-specific mortality, and reductions in life expectancy. Methods: For this observational study, we conducted a combined analysis of individual-participant data from 19 high-income countries using two large-scale data sources: the Emerging Risk Factors Collaboration (96 cohorts, median baseline years 1961–2007, median latest follow-up years 1980–2013) and the UK Biobank (median baseline year 2006, median latest follow-up year 2020). We calculated age-adjusted and sex-adjusted hazard ratios (HRs) for all-cause mortality according to age at diagnosis of diabetes using data from 1 515 718 participants, in whom deaths were recorded during 23·1 million person-years of follow-up. We estimated cumulative survival by applying age-specific HRs to age-specific death rates from 2015 for the USA and the EU. Findings: For participants with diabetes, we observed a linear dose–response association between earlier age at diagnosis and higher risk of all-cause mortality compared with participants without diabetes. HRs were 2·69 (95% CI 2·43–2·97) when diagnosed at 30–39 years, 2·26 (2·08–2·45) at 40–49 years, 1·84 (1·72–1·97) at 50–59 years, 1·57 (1·47–1·67) at 60–69 years, and 1·39 (1·29–1·51) at 70 years and older. HRs per decade of earlier diagnosis were similar for men and women. Using death rates from the USA, a 50-year-old individual with diabetes died on average 14 years earlier when diagnosed aged 30 years, 10 years earlier when diagnosed aged 40 years, or 6 years earlier when diagnosed aged 50 years than an individual without diabetes. Using EU death rates, the corresponding estimates were 13, 9, or 5 years earlier. Interpretation: Every decade of earlier diagnosis of diabetes was associated with about 3–4 years of lower life expectancy, highlighting the need to develop and implement interventions that prevent or delay the onset of diabetes and to intensify the treatment of risk factors among young adults diagnosed with diabetes. Funding: British Heart Foundation, Medical Research Council, National Institute for Health and Care Research, and Health Data Research UK

    Mineralogical and geochemical analysis of Fe-phases in drill-cores from the Triassic Stuttgart Formation at Ketzin CO₂ storage site before CO₂ arrival

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    Reactive iron (Fe) oxides and sheet silicate-bound Fe in reservoir rocks may affect the subsurface storage of CO2 through several processes by changing the capacity to buffer the acidification by CO2 and the permeability of the reservoir rock: (1) the reduction of three-valent Fe in anoxic environments can lead to an increase in pH, (2) under sulphidic conditions, Fe may drive sulphur cycling and lead to the formation of pyrite, and (3) the leaching of Fe from sheet silicates may affect silicate diagenesis. In order to evaluate the importance of Fe-reduction on the CO2 reservoir, we analysed the Fe geochemistry in drill-cores from the Triassic Stuttgart Formation (Schilfsandstein) recovered from the monitoring well at the CO2 test injection site near Ketzin, Germany. The reservoir rock is a porous, poorly to moderately cohesive fluvial sandstone containing up to 2–4 wt% reactive Fe. Based on a sequential extraction, most Fe falls into the dithionite-extractable Fe-fraction and Fe bound to sheet silicates, whereby some Fe in the dithionite-extractable Fe-fraction may have been leached from illite and smectite. Illite and smectite were detected in core samples by X-ray diffraction and confirmed as the main Fe-containing mineral phases by X-ray absorption spectroscopy. Chlorite is also present, but likely does not contribute much to the high amount of Fe in the silicate-bound fraction. The organic carbon content of the reservoir rock is extremely low (<0.3 wt%), thus likely limiting microbial Fe-reduction or sulphate reduction despite relatively high concentrations of reactive Fe-mineral phases in the reservoir rock and sulphate in the reservoir fluid. Both processes could, however, be fuelled by organic matter that is mobilized by the flow of supercritical CO2 or introduced with the drilling fluid. Over long time periods, a potential way of liberating additional reactive Fe could occur through weathering of silicates due to acidification by CO2
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