736 research outputs found

    The use of national datasets to baseline science education reform: exploring value-added approaches

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    This paper uses data from the National Pupil Database to investigate the differences in ‘performance’ across the range of science courses available following the 2006 Key Stage 4 (KS4) science reforms in England. This is a value-added exploration (from Key Stage 3 [KS3] to KS4) aimed not at the student or the school level, but rather at that of the course. Different methodological approaches to carrying out such an analysis, ranging from simple non-contextualized techniques, to more complex fully contextualized multilevel models, are investigated and their limitations and benefits are evaluated. Important differences between courses are found in terms of the typical ‘value’ they add to the students studying them with particular applied science courses producing higher mean KS4 outcomes for the same KS3 level compared with other courses. The implications of the emergence of such differences, in a context where schools are judged to a great extent on their value-added performance, are discussed. The relative importance of a variety of student characteristics in determining KS4 outcomes are also investigated. Substantive findings are that across all types of course, science prior attainment at KS3, rather than that of mathematics or English, is the most important predictor of KS4 performance in science, and that students of lower socio-economic status consistently make less progress over KS4 than might be expected, despite prior attainment being accounted for in the modelling

    Autopsy examination in sudden cardiac death: a current perspective on behalf of the Association for European Cardiovascular Pathology.

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    In sudden cardiac death, an autopsy is an essential step in establishing a diagnosis of inherited cardiac disease and identifying families that require cardiac screening. To evaluate aspects of post-mortem practice in Europe, a questionnaire was designed and circulated to both clinical and forensic pathologists. There was a 48% response rate and information was obtained from 17 countries. The results showed a wide variety in the management of sudden cardiac death, with a general tendency towards a lack of thorough investigation. In up to 40% of cases, autopsies were not performed in subjects less than 50 years who may have died from cardiac disease. Reasons for this were lack of finance and lack of interest from police, legal authorities, and doctors. Only 50% of pathologists seem to follow a standard protocol for autopsy examination, apparently due to lack of expertise and/or training. When autopsies were performed, histology and toxicology were almost always taken, genetic studies were generally available and retention of the heart for specialist study was usually permitted. Our results suggest that although the standard of practice is appropriate in many centres, many more cases should have autopsies, especially in sudden deaths in subjects less than 50 years

    INCLUSIVE PARTICLE PRODUCTION IN \pbp COLLISIONS

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    We calculate the inclusive production of charged hadrons in \pbp collisions to next-to-leading order (NLO) in the QCD improved parton model using a new set of NLO fragmentation functions for charged pions and kaons. We predict transverse-momentum distributions and compare them with experimental data from the CERN S\pbpS Collider and the Fermilab Tevatron.Comment: the file containing the figures has been replaced: we correct a mistake in the uuencoding procedure and we give the real Fig 4 instead of the spurious one which was accidentally included in the previous file. the text is unchanged

    Power Law in Hadron Production

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    In high energy p+p(bar) interactions the mean multiplicity and transverse mass spectra of neutral mesons from eta to Upsilon (m = 0.5 - 10 GeV/c^2) and the transverse mass spectra of pions (m_T > 1 GeV/c^2) reveal a remarkable behaviour: they follow, over more than 10 orders of magnitude, the power-law function:The parameters C and P are energy dependent, but similar for all mesons produced at the same collision energy. This scaling resembles that expected in the statistical description of hadron production: the parameter P plays the role of a temperature and the normalisation constant C is analogous to the system volume. The fundamental difference is, however, in the form of the distribution function. In order to reproduce the experimental results and preserve the basic structure of the statistical approach the Boltzmann factor e^(-E/T) appearing in standard statistical mechanics has to be substituted by a power-law factor (E/Lambda)^(-P).Comment: significantly revised version to appear in Phys. Lett.

    Is rejection a diffuse or localized process in small-bowel transplantation?

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    Utilization of endoscopy to both visualize and selectively biopsy an intestinal allograft has become the standard for early recognition and treatment of intestinal allograft rejection. Despite the widespread acceptance of the need for selective mucosal biopsies, it has not been shown that the histological features of intestinal allograft rejection are either localized or occur as part of a more diffuse phenomenon within a tubular allograft. To resolve these issues, 88 ileoscopies were performed in 12 small-bowel allograft recipients and mucosal biopsy samples were obtained at 5, 10, and 15 cm, respectively, from the ileal stoma. Each mucosal biopsy was labeled, processed, and evaluated individually for the presence and severity of any evidence for allograft rejection. The data obtained suggest that intestinal allograft rejection is a diffuse process, and biopsies obtained randomly from an ileal graft are likely to demonstrate evidence of allograft rejection when such is present. © 1994 Springer-Verlag New York Inc

    The selective phosphodiesterase 4 inhibitor roflumilast and phosphodiesterase 3/4 inhibitor pumafentrine reduce clinical score and TNF expression in experimental colitis in mice.

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    The specific inhibition of phosphodiesterase (PDE)4 and dual inhibition of PDE3 and PDE4 has been shown to decrease inflammation by suppression of pro-inflammatory cytokine synthesis. We examined the effect of roflumilast, a selective PDE4 inhibitor marketed for severe COPD, and the investigational compound pumafentrine, a dual PDE3/PDE4 inhibitor, in the preventive dextran sodium sulfate (DSS)-induced colitis model. The clinical score, colon length, histologic score and colon cytokine production from mice with DSS-induced colitis (3.5% DSS in drinking water for 11 days) receiving either roflumilast (1 or 5 mg/kg body weight/d p.o.) or pumafentrine (1.5 or 5 mg/kg/d p.o.) were determined and compared to vehicle treated control mice. In the pumafentrine-treated animals, splenocytes were analyzed for interferon-γ (IFNγ) production and CD69 expression. Roflumilast treatment resulted in dose-dependent improvements of clinical score (weight loss, stool consistency and bleeding), colon length, and local tumor necrosis factor-α (TNFα) production in the colonic tissue. These findings, however, were not associated with an improvement of the histologic score. Administration of pumafentrine at 5 mg/kg/d alleviated the clinical score, the colon length shortening, and local TNFα production. In vitro stimulated splenocytes after in vivo treatment with pumafentrine showed a significantly lower state of activation and production of IFNγ compared to no treatment in vivo. These series of experiments document the ameliorating effect of roflumilast and pumafentrine on the clinical score and TNF expression of experimental colitis in mice

    Wave modelling - the state of the art

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    This paper is the product of the wave modelling community and it tries to make a picture of the present situation in this branch of science, exploring the previous and the most recent results and looking ahead towards the solution of the problems we presently face. Both theory and applications are considered. The many faces of the subject imply separate discussions. This is reflected into the single sections, seven of them, each dealing with a specific topic, the whole providing a broad and solid overview of the present state of the art. After an introduction framing the problem and the approach we followed, we deal in sequence with the following subjects: (Section) 2, generation by wind; 3, nonlinear interactions in deep water; 4, white-capping dissipation; 5, nonlinear interactions in shallow water; 6, dissipation at the sea bottom; 7, wave propagation; 8, numerics. The two final sections, 9 and 10, summarize the present situation from a general point of view and try to look at the future developments

    Time Reversal Violation from the entangled B0-antiB0 system

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    We discuss the concepts and methodology to implement an experiment probing directly Time Reversal (T) non-invariance, without any experimental connection to CP violation, by the exchange of "in" and "out" states. The idea relies on the B0-antiB0 entanglement and decay time information available at B factories. The flavor or CP tag of the state of the still living neutral meson by the first decay of its orthogonal partner overcomes the problem of irreversibility for unstable systems, which prevents direct tests of T with incoherent particle states. T violation in the time evolution between the two decays means experimentally a difference between the intensities for the time-ordered (l^+ X, J/psi K_S) and (J/psi K_L, l^- X) decays, and three other independent asymmetries. The proposed strategy has been applied to simulated data samples of similar size and features to those currently available, from which we estimate the significance of the expected discovery to reach many standard deviations.Comment: 17 pages, 2 figures, 6 table

    Propagation of chaos for rank-based interacting diffusions and long time behaviour of a scalar quasilinear parabolic equation

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    We study a quasilinear parabolic Cauchy problem with a cumulative distribution function on the real line as an initial condition. We call 'probabilistic solution' a weak solution which remains a cumulative distribution function at all times. We prove the uniqueness of such a solution and we deduce the existence from a propagation of chaos result on a system of scalar diffusion processes, the interactions of which only depend on their ranking. We then investigate the long time behaviour of the solution. Using a probabilistic argument and under weak assumptions, we show that the flow of the Wasserstein distance between two solutions is contractive. Under more stringent conditions ensuring the regularity of the probabilistic solutions, we finally derive an explicit formula for the time derivative of the flow and we deduce the convergence of solutions to equilibrium.Comment: Stochastic partial differential equations: analysis and computations (2013) http://dx.doi.org/10.1007/s40072-013-0014-
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