627 research outputs found

    Linking phytoplankton community metabolism to the individual size distribution

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    This is the final version of the article. Available from the publisher via the DOI in this recordQuantifying variation in ecosystem metabolism is critical to predicting the impacts of environmental change on the carbon cycle. We used a metabolic scaling framework to investigate how body size and temperature influence phytoplankton community metabolism. We tested this framework using phytoplankton sampled from an outdoor mesocosm experiment, where communities had been either experimentally warmed (+ 4 °C) for 10 years or left at ambient temperature. Warmed and ambient phytoplankton communities differed substantially in their taxonomic composition and size structure. Despite this, the response of primary production and community respiration to long- and short-term warming could be estimated using a model that accounted for the size- and temperature dependence of individual metabolism, and the community abundance-body size distribution. This work demonstrates that the key metabolic fluxes that determine the carbon balance of planktonic ecosystems can be approximated using metabolic scaling theory, with knowledge of the individual size distribution and environmental temperature.NERC. Grant Number: PASW06

    An analysis of technology gaps and priorities in support of probe-scale coronagraph and starshade missions

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    This paper provides a survey of the state-of-the-art in coronagraph and starshade technologies and highlights areas where advances are needed to enable future NASA exoplanet missions. An analysis is provided of the remaining technology gaps and the relative priorities of technology investments leading to a mission that could follow JWST. This work is being conducted in support of NASAs Astrophysics Division and the NASA Exoplanet Exploration Program (ExEP), who are in the process of assessing options for future missions. ExEP has funded Science and Technology Definition Teams to study coronagraphs and starshade mission concepts having a lifecycle cost cap of less than $1B. This paper provides a technology gap analysis for these concepts

    Multiple agency perspective, family control, and private information abuse in an emerging economy

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    Using a comprehensive sample of listed companies in Hong Kong this paper investigates how family control affects private information abuses and firm performance in emerging economies. We combine research on stock market microstructure with more recent studies of multiple agency perspectives and argue that family ownership and control over the board increases the risk of private information abuse. This, in turn, has a negative impact on stock market performance. Family control is associated with an incentive to distort information disclosure to minority shareholders and obtain private benefits of control. However, the multiple agency roles of controlling families may have different governance properties in terms of investors’ perceptions of private information abuse. These findings contribute to our understanding of the conflicting evidence on the governance role of family control within a multiple agency perspectiv

    Systematic review of the incidence and clinical risk predictors of atrial fibrillation and permanent pacemaker implantation for bradycardia in Fabry disease

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    INTRODUCTION: Fabry disease (FD) is an X-linked lysosomal storage disorder caused by enzyme deficiency, leading to glycosphingolipid accumulation. Cardiac accumulation triggers local tissue injury, electrical instability and arrhythmia. Bradyarrhythmia and atrial fibrillation (AF) incidence are reported in up to 16% and 13%, respectively. OBJECTIVE: We conducted a systematic review evaluating AF burden and bradycardia requiring permanent pacemaker (PPM) implantation and report any predictive risk factors identified. METHODS: We conducted a literature search on studies in adults with FD published from inception to July 2019. Study outcomes included AF or bradycardia requiring therapy. Databases included Embase, Medline, PubMed, Web of Science, CINAHL and Cochrane. The Risk of Bias Agreement tool for Non-Randomised Studies (RoBANS) was utilised to assess bias across key areas. RESULTS: 11 studies were included, eight providing data on AF incidence or PPM implantation. Weighted estimate of event rates for AF were 12.2% and 10% for PPM. Age was associated with AF (OR 1.05–1.20 per 1-year increase in age) and a risk factor for PPM implantation (composite OR 1.03). Left ventricular hypertrophy (LVH) was associated with AF and PPM implantation. CONCLUSION: Evidence supporting AF and bradycardia requiring pacemaker implantation is limited to single-centre studies. Incidence is variable and choice of diagnostic modality plays a role in detection rate. Predictors for AF (age, LVH and atrial dilatation) and PPM (age, LVH and PR/QRS interval) were identified but strength of association was low. Incidence of AF and PPM implantation in FD are variably reported with arrhythmia burden likely much higher than previously thought

    Block public access: Trust safety verification of access control policies

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    © 2020 Owner/Author. Data stored in cloud services is highly sensitive and so access to it is controlled via policies written in domain-specific languages (DSLs). The expressiveness of these DSLs provides users flexibility to cover a wide variety of uses cases, however, unintended misconfigurations can lead to potential security issues. We introduce Block Public Access, a tool that formally verifies policies to ensure that they only allow access to trusted principals, i.e. that they prohibit access to the general public. To this end, we formalize the notion of Trust Safety that formally characterizes whether or not a policy allows unconstrained (public) access. Next, we present a method to compile the policy down to a logical formula whose unsatisfiability can be (1) checked by SMT and (2) ensures Trust Safety. The constructs of the policy DSLs render unsatisfiability checking PSPACE-complete, which precludes verifying the millions of requests per second seen at cloud scale. Hence, we present an approach that leverages the structure of the policy DSL to compute a much smaller residual policy that corresponds only to untrusted accesses. Our approach allows Block Public Access to, in the common case, syntactically verify Trust Safety without having to query the SMT solver. We have implemented Block Public Access and present an evaluation showing how the above optimization yields a low-latency policy verifier that the S3 team at AWS has integrated into their authorization system, where it is currently in production, analyzing millions of policies everyday to ensure that client buckets do not grant unintended public access

    The K2 Galactic Archaeology Program Data Release 2: Asteroseismic Results from Campaigns 4, 6, and 7

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    Studies of Galactic structure and evolution have benefited enormously from Gaia kinematic information, though additional, intrinsic stellar parameters like age are required to best constrain Galactic models. Asteroseismology is the most precise method of providing such information for field star populations en masse, but existing samples for the most part have been limited to a few narrow fields of view by the CoRoT and Kepler missions. In an effort to provide well-characterized stellar parameters across a wide range in Galactic position, we present the second data release of red giant asteroseismic parameters for the K2 Galactic Archaeology Program (GAP). We provide V_{max} and Delta_{v} based on six independent pipeline analyses; first-ascent red giant branch (RGB) and red clump (RC) evolutionary state classifications from machine learning; and ready-to-use radius and mass coefficients, K_{R} and K_{M}, which, when appropriately multiplied by a solar-scaled effective temperature factor, yield physical stellar radii and masses. In total, we report 4395 radius and mass coefficients, with typical uncertainties of 3.3% (stat.) ± 1% (syst.) for K_{R} and 7.7% (stat.) ± 2% (syst.) for κM among RGB stars, and 5.0% (stat.) ± 1% (syst.) for K_{R} nd 10.5% (stat.) ± 2% (syst.) for κM among RC stars. We verify that the sample is nearly complete—except for a dearth of stars with V_{max} \leqslant 10-20 mHz-by comparing to Galactic models and visual inspection. Our asteroseismic radii agree with radii derived from Gaia Data Release 2 parallaxes to within 2.2% ± 0.3% for RGB stars and 2.0% ± 0.6% for RC stars

    Managing Knowledge in Policymaking and Decision Making

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    The combined effect of increasing problem complexity and growing demand for participation in decisions has forced policymaking and decision making in organizations to become less an analytic endeavor and more a process of "knowledge management ' This requires an intermediarv to mediate among conflicting perspectives and integrate the different forms and levels of knowledge This article describes one such approach to knowledge management that utilizes a third party to create and facilitate a temporary task organization Following a brief case example, some research resultsfrom an evaluation of six past applications of the approach are presented These results provide insight into the effective structuring and conduct of knowledge management proceduresPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68626/2/10.1177_107554708600800106.pd

    Presurgical language fMRI: Clinical practices and patient outcomes in epilepsy surgical planning

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    The goal of this study was to document current clinical practice and report patient outcomes in presurgical language functional MRI (fMRI) for epilepsy surgery. Epilepsy surgical programs worldwide were surveyed as to the utility, implementation, and efficacy of language fMRI in the clinic; 82 programs responded. Respondents were predominantly US (61%) academic programs (85%), and evaluated adults (44%), adults and children (40%), or children only (16%). Nearly all (96%) reported using language fMRI. Surprisingly, fMRI is used to guide surgical margins (44% of programs) as well as lateralize language (100%). Sites using fMRI for localization most often use a distance margin around activation of 10mm. While considered useful, 56% of programs reported at least one instance of disagreement with other measures. Direct brain stimulation typically confirmed fMRI findings (74%) when guiding margins, but instances of unpredicted decline were reported by 17% of programs and 54% reported unexpected preservation of function. Programs reporting unexpected decline did not clearly differ from those which did not. Clinicians using fMRI to guide surgical margins do not typically map known language-critical areas beyond Broca's and Wernicke's. This initial data shows many clinical teams are confident using fMRI not only for language lateralization but also to guide surgical margins. Reported cases of unexpected language preservation when fMRI activation is resected, and cases of language decline when it is not, emphasize a critical need for further validation. Comprehensive studies comparing commonly-used fMRI paradigms to predict stimulation mapping and post-surgical language decline remain of high importance

    The impact of ownership structure on earnings quality: the case of South Korea

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    © 2018, Macmillan Publishers Ltd., part of Springer Nature. This paper investigates the impact of business group ownership structure on the quality of earnings reporting using data from South Korea. In addition, we investigate the impact of ownership disparity and family ownership on earnings quality reporting. Using a self-constructed earnings quality index as a measure of earnings quality, we found that business group ownership structure is significantly associated with higher earnings quality. The result suggests that strong monitoring mechanisms introduced by the government, which are necessary for credibility in external financial markets and beneficial to business group reputation, led to increased transparency in earnings reports. We also found that disparity in ownership between control and cash flow rights in firms, as well as family ownership in group firms, was both associated with lower earnings quality
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