207 research outputs found

    Inverse Compton X-rays from relativistic flare electrons and positrons

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    <p><b>Context:</b> In solar flares, inverse Compton scattering (ICS) of photospheric photons might give rise to detectable hard X-ray photon fluxes from the corona where ambient densities are too low for significant bremsstrahlung or recombination. γ-ray lines and continuum in some large flares imply the presence of the necessary ~100 MeV electrons and positrons, the latter as by-products of GeV energy ions. Recent observations of coronal hard X-ray sources in particular prompt us to reconsider here the possible contribution of ICS.</p> <p><b>Aims:</b> We aim to evaluate the ICS X-ray fluxes to be expected from prescribed populations of relativistic electrons and positrons in the solar corona. The ultimate aim is to determine if ICS coronal X-ray sources might offer a new diagnostic window on relativistic electrons and ions in flares.</p> <p><b>Methods:</b> We use the complete formalism of ICS to calculate X-ray fluxes from possible populations of flare primary electrons and secondary positrons, paying attention to the incident photon angular distribution near the solar surface and thus improving on the assumption of isotropy made in previous solar discussions.</p> <p><b>Results:</b> Both primary electrons and secondary positrons produce very hard ICS X-ray spectra. The anisotropic primary radiation field results in pronounced centre-to-limb variation in predicted fluxes and spectra, with the most intense spectra, extending to the highest photon energies, expected from limb flares. Acceptable numbers of electrons or positrons could account for RHESSI coronal X/γ-ray sources.</p> <p><b>Conclusions:</b> Some coronal X-ray sources at least might be interpreted in terms of ICS by relativistic electrons or positrons, particularly when sources appear at such low ambient densities that bremsstrahlung appears implausible.</p&gt

    Navigating 'the pit of doom': Affective responses to teaching 'grammar'

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    publication-status: Publishedtypes: ArticleThis article presents the outcomes of a study investigating current secondary English teachers' beliefs about grammar teaching, and illustrates the salience of teachers' emotional response to the issue. Interviews with 31 teachers reveal two discourses which frame the ways in which teachers express their feelings: a dominant discourse of grammar as threatening, reactionary and dull, and an oppositional discourse which positions grammar as inspiring, fascinating, and empowering. The influence of these discourses on practice is explored, along with examples of how attitudes can change as a result of participation in a research project. © 2012 National Association for the Teaching of English

    The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: measuring structure growth using passive galaxies

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    We explore the benefits of using a passively evolving population of galaxies to measure the evolution of the rate of structure growth between z=0.25 and z=0.65 by combining data from the SDSS-I/II and SDSS-III surveys. The large-scale linear bias of a population of dynamically passive galaxies, which we select from both surveys, is easily modeled. Knowing the bias evolution breaks degeneracies inherent to other methodologies, and decreases the uncertainty in measurements of the rate of structure growth and the normalization of the galaxy power-spectrum by up to a factor of two. If we translate our measurements into a constraint on sigma_8(z=0) assuming a concordance cosmological model and General Relativity (GR), we find that using a bias model improves our uncertainty by a factor of nearly 1.5. Our results are consistent with a flat Lambda Cold Dark Matter model and with GR.Comment: Accepted for publication in MNRAS (clarifications added, results and conclusions unchanged

    Change or control? Developing dialogues between research and public protection

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    This paper aims to scope out some of the implications of desistance research for the community management of high risk offenders. Acknowledging the limited empirical research exploring this interface, this paper outlines the evolving evidence base and what this tells us about the process of desistance and what supports it. The evidence as to whether 'high risk offenders' desist and what we know about this process is discussed prior to outlining the landscape of current and principal practice approaches which can be located in the community/public protection model. Potential dialogues between desistance research and public protection practices are discussed to explore ensuing implications and opportunities for practice

    Effects of Selective Matrix Metalloproteinase Inhibitor (PG-116800) to Prevent Ventricular Remodeling After Myocardial Infarction Results of the PREMIER (Prevention of Myocardial Infarction Early Remodeling) Trial

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    ObjectivesWe sought to determine whether matrix metalloproteinase (MMP) inhibitor, PG-116800, reduced left ventricular (LV) remodeling after myocardial infarction (MI).BackgroundPG-116800 is an oral MMP inhibitor with significant antiremodeling effects in animal models of MI and ischemic heart failure.MethodsIn an international, randomized, double-blind, placebo-controlled study, 253 patients with first ST-segment elevation MI and ejection fraction between 15% and 40% were enrolled 48± 24 h after MI and treated with placebo or PG-116800 for 90 days. Major efficacy end points were changes in LV volumes as determined by serial echocardiography, and clinical and safety outcomes were also collected.ResultsIn total, 203 patients (80%) completed 90 days of treatment and had evaluable baseline and 90-day echocardiograms. The proportion of patients with anterior MI (78% vs. 81%) and primary percutaneous coronary intervention (90% vs. 91%) along with baseline LV ejection fraction (35.5% vs. 36.8%) did not differ between PG-116800-treated and placebo-treated patients. There was no difference in the change in LV end-diastolic volume index from days 0 to 90 with PG-116800 versus placebo (5.09 ± 1.45 ml/m2vs. 5.48 ± 1.41 ml/m2, p = 0.42). Changes in LV diastolic volume, LV systolic volume, LV ejection fraction, sphericity index, plus rates of death or reinfarction were not significantly improved with PG-116800. PG-116800 was well tolerated; however, there was increased incidence of arthralgia and joint stiffness without significant increase in overall musculoskeletal adverse events (21% vs. 15%, p = 0.33).ConclusionsMatrix metalloproteinase inhibition with PG-116800 failed to reduce LV remodeling or improve clinical outcomes after MI

    Policy failure and the policy-implementation gap: can policy support programs help?

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    There is an increasing awareness that policies do not succeed or fail on their own merits. Within complex messy systems, it is unclear how best to ensure effective policy design and implementation. However, rather than just let policies drift into full or even partial failure, governments are now beginning to take an interest in ways in which the policy process – especially the implementation phase – can be strengthened and supported. This article contributes to the debate in three ways: by unpicking the key factors behind policy failure; by exploring different approaches to policy support; and by identifying key messages for policy practitioners

    Overview of the VA Quality Enhancement Research Initiative (QUERI) and QUERI theme articles: QUERI Series

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    <p>Abstract</p> <p>Background</p> <p>Continuing challenges to timely adoption of evidence-based clinical practices in healthcare have generated intense interest in the development and application of new implementation methods and frameworks. These challenges led the United States (U.S.) Department of Veterans Affairs (VA) to create the Quality Enhancement Research Initiative (QUERI) in the late 1990s. QUERI's purpose was to harness VA's health services research expertise and resources in an ongoing system-wide effort to improve the performance of the VA healthcare system and, thus, quality of care for veterans. QUERI in turn created a systematic means of involving VA researchers both in enhancing VA healthcare quality, by implementing evidence-based practices, and in contributing to the continuing development of implementation science.</p> <p>The efforts of VA researchers to improve healthcare delivery practices through QUERI and related initiatives are documented in a growing body of literature. The scientific frameworks and methodological approaches developed and employed by QUERI are less well described. A QUERI Series of articles in <it>Implementation Science </it>will illustrate many of these QUERI tools. This <it>Overview </it>article introduces both QUERI and the Series.</p> <p>Methods</p> <p>The <it>Overview </it>briefly explains the purpose and context of the QUERI Program. It then describes the following: the key operational structure of QUERI Centers, guiding frameworks designed to enhance implementation and related research, QUERI's progress and promise to date, and the Series' general content. QUERI's frameworks include a core set of steps for diagnosing and closing quality gaps and, simultaneously, advancing implementation science. Throughout the paper, the envisioned involvement and activities of VA researchers within QUERI Centers also are highlighted. The Series is then described, illustrating the use of QUERI frameworks and other tools designed to respond to implementation challenges.</p> <p>Conclusion</p> <p>QUERI's simultaneous pursuit of improvement and research goals within a large healthcare system may be unique. However, descriptions of this still-evolving effort, including its conceptual frameworks, methodological approaches, and enabling processes, should have applicability to implementation researchers in a range of health care settings. Thus, the <it>Series </it>is offered as a resource for other implementation research programs and researchers pursuing common goals in improving care and developing the field of implementation science.</p

    Methodological Guidelines for Engineering Self-organization and Emergence

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    The ASCENS project deals with the design and development of complex self-adaptive systems, where self-organization is one of the possible means by which to achieve self-adaptation. However, to support the development of self-organising systems, one has to extensively re-situate their engineering from a software architectures and requirements point of view. In particular, in this chapter, we highlight the importance of the decomposition in components to go from the problem to the engineered solution. This leads us to explain and rationalise the following architectural strategy: designing by following the problem organisation. We discuss architectural advantages for development and documentation, and its coherence with existing methodological approaches to self-organisation, and we illustrate the approach with an example on the area of swarm robotics

    The genomes of two key bumblebee species with primitive eusocial organization

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    Background: The shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats. Results: We report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits. Conclusions: These two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation

    An International Comparison of Presentation, Outcomes and CORONET Predictive Score Performance in Patients with Cancer Presenting with COVID-19 across Different Pandemic Waves.

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    Patients with cancer have been shown to have increased risk of COVID-19 severity. We previously built and validated the COVID-19 Risk in Oncology Evaluation Tool (CORONET) to predict the likely severity of COVID-19 in patients with active cancer who present to hospital. We assessed the differences in presentation and outcomes of patients with cancer and COVID-19, depending on the wave of the pandemic. We examined differences in features at presentation and outcomes in patients worldwide, depending on the waves of the pandemic: wave 1 D614G (n = 1430), wave 2 Alpha (n = 475), and wave 4 Omicron variant (n = 63, UK and Spain only). The performance of CORONET was evaluated on 258, 48, and 54 patients for each wave, respectively. We found that mortality rates were reduced in subsequent waves. The majority of patients were vaccinated in wave 4, and 94% were treated with steroids if they required oxygen. The stages of cancer and the median ages of patients significantly differed, but features associated with worse COVID-19 outcomes remained predictive and did not differ between waves. The CORONET tool performed well in all waves, with scores in an area under the curve (AUC) of &gt;0.72. We concluded that patients with cancer who present to hospital with COVID-19 have similar features of severity, which remain discriminatory despite differences in variants and vaccination status. Survival improved following the first wave of the pandemic, which may be associated with vaccination and the increased steroid use in those patients requiring oxygen. The CORONET model demonstrated good performance, independent of the SARS-CoV-2 variants
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