3,497 research outputs found

    Pion-pion scattering and the diffractive production of nucleon resonances

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    The physics related to two aspects of the π N → π π N reaction is studied. We first consider the imposition of the constraints of analyticity, unitarity and, in particular, crossing, on the pion-pion scattering amplitudes, as extracted from studies of the low dipion mass kinematic region of the π N → π π N reaction. The application of the Roy equations to pion-pion scattering is discussed, then physical region crossing sum rules are systematically derived and applied, in conjunction with finite energy sum rules, to obtain information on the asymptotic pion-pion scattering amplitudes. The amplitudes are found to be well described in terms of Regge and pomeron exchange, with rho-f strong exchange degeneracy broken and an asymptotic total cross section for pion-pion scattering rather smaller than that expected from naive factorization arguments. Other evidence for a small meson-meson scattering asymptotic total cross section is collected, and possible explanations for the apparent failure of the pomeron to factorize are discussed. The second part of this thesis deals with diffraction dissociation processes. We discuss how the Deck-Drell-Hiida mechanism, in conjunction with the diffractive production, and subsequent decay, of resonances provides a good qualitative explanation of many of the features of inelastic diffractive scattering. Detailed data on the angular distributions of the diffractively produced pion-nucleon system in the 16 GeV. π N → π π N reaction are then interpreted quantitatively in terms of a simple model based on the above ideas, with full account taken of spin and interference effects. Information is obtained on the pomeron couplings, and the high energy t channel isospin zero pion-pion scattering amplitude, directly determined, is found to be consistent with the sum rule calculation results and a small asymptotic pion-pion scattering total cross section

    Amantadine hydrochloride in the treatment of parkinsonism: A placebo-controlled double-blind study

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    This report covers a review of the literature and a description of a double-blind placebo-controlled trial, of 200 mg of amantadine hydrochloride daily in the treatment of 23 parkinsonian patients. Statistical analysis of clinical results showed a significant improvement in rigidity and tremor at rest and a fair improvement in initiating movements and alertness. Subjective mood elevation was not confirmed by statistical analysis. Gait, voice control, jaw tremor and salivation showed no statistical improvement, while eye convergence may be adversely affected. Side-effects were minimal. Amantadine hydrochloride (Symmetrel, Geigy) appears to have real value in the treatment of parkinsonism

    Perceptions on the role of evidence: an English alcohol policy case study

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    This paper explores the competing influences which inform public health policy and describes the role that research evidence plays within the policy-making process. In particular it draws on a recent English alcohol policy case study to assess the role of evidence in informing policy and practice. Semi-structured interviews with key national, regional and local policy informants were transcribed and analysed thematically. A strong theme identified was that of the role of evidence. Findings are discussed in the context of competing views on what constitutes appropriate evidence for policy-making

    Soft methods, hard targets: regional alcohol managers as a policy network

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    Regional Alcohol Managers (RAMs) was employed in the nine English health regions over 2008–2011. Their mission was to impact on the ‘hard target’ of Alcohol-Related Hospital Admissions (AHRAs) through the ‘soft methods’ of persuasion and influence: working with local partners on evidence-based interventions. Drawing on a qualitative evaluation, this article shows how a central government policy imperative (ARHAs) led to ‘government at a distance’ responses, including the introduction of RAMs. The processes involved in shaping and delivering this function bore the hallmarks of a complex, interactive policy network model, involving individuals whose bearings and roles were flexible and sometimes ambiguous. While there were overlaps and blurring of boundaries, there were three levels of policy network: central government, regional and local. As the ‘network in the middle’, the RAMs were pulled in both directions by conflicting agendas but were also able to have an impact on central and local policy

    Mode identification in rapidly rotating stars

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    Context: Recent calculations of pulsation modes in rapidly rotating polytropic models and models based on the Self-Consistent Field method have shown that the frequency spectrum of low degree pulsation modes can be described by an empirical formula similar to Tassoul's asymptotic formula, provided that the underlying rotation profile is not too differential. Aims: Given the simplicity of this asymptotic formula, we investigate whether it can provide a means by which to identify pulsation modes in rapidly rotating stars. Methods: We develop a new mode identification scheme which consists in scanning a multidimensional parameter space for the formula coefficients which yield the best-fitting asymptotic spectra. This mode identification scheme is then tested on artificial spectra based on the asymptotic formula, on random frequencies and on spectra based on full numerical eigenmode calculations for which the mode identification is known beforehand. We also investigate the effects of adding random frequencies to mimic the effects of chaotic modes which are also expected to show up in such stars. Results: In the absence of chaotic modes, it is possible to accurately find a correct mode identification for most of the observed frequencies provided these frequencies are sufficiently close to their asymptotic values. The addition of random frequencies can very quickly become problematic and hinder correct mode identification. Modifying the mode identification scheme to reject the worst fitting modes can bring some improvement but the results still remain poorer than in the case without chaotic modes

    The alcohol improvement programme: evaluation of an initiative to address alcohol-related health harm in England

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    Aims: The evaluation aimed to assess the impact of The Alcohol Improvement Programme (AIP). This was a UK Department of Health initiative (April 2008–March 2011) aiming to contribute to the reduction of alcohol-related harm as measured by a reduction in the rate of increase in alcohol-related hospital admissions (ARHAs). Methods: The evaluation (March 2010–September 2011) used a mix of qualitative and quantitative methods to assess the impact of the AIP on ARHAs, to describe and assess the process of implementation, and to identify elements of the programme which might serve as a ‘legacy’ for the future. Results: There was no evidence that the AIP had an impact on reducing the rise in the rate of ARHAs. The AIP was successfully delivered, increased the priority given to alcohol-related harm on local policy agendas and strengthened the infrastructure for the delivery of interventions. Conclusion: Although there was no measurable short-term impact on the rise in the rate of ARHAs, the AIP helped to set up a strategic response and a delivery infrastructure as a first, necessary step in working towards that goal. There are a number of valuable elements in the AIP which should be retained and repackaged to fit into new policy contexts

    Infrequent small bowel intestinal bacterial overgrowth in malnourished Zambian children.

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    There is evidence that children with malnutrition have an increased frequency of small intestinal bacterial overgrowth (SIBO) due to impaired gastric acidity, impaired intestinal motility, and dysbiosis. Children with malnutrition respond to antibiotic therapy but it is not clear if this effect is mediated by treatment of SIBO. We set out to determine the frequency of SIBO in children of varying nutritional status in a poor community in Lusaka, Zambia. Hydrogen breath testing, following a dose of 1g/kg oral glucose, was used to determine the presence of SIBO amongst the study participants. Forty nine children, 45 of whom had varying degrees of malnutrition, completed a full series of observations at 15, 30 and 60 minutes. Four children (8%) had a rise of 10ppm from baseline, consistent with SIBO. No correlation with nutritional status was observed. In this small study of Zambian children, SIBO was infrequent and unrelated to nutritional status

    Archaeological Excavations at Nethermills Farm, Deeside, 1978-81

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    This publication is grant aided by Historic Environment Scotland.Peer reviewedPublisher PD

    Technical Design Report for the PANDA Micro Vertex Detector

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    This document illustrates the technical layout and the expected performance of the Micro Vertex Detector (MVD) of the PANDA experiment. The MVD will detect charged particles as close as possible to the interaction zone. Design criteria and the optimisation process as well as the technical solutions chosen are discussed and the results of this process are subjected to extensive Monte Carlo physics studies. The route towards realisation of the detector is outlined

    Technical Design Report for PANDA Electromagnetic Calorimeter (EMC)

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    This document presents the technical layout and the envisaged performance of the Electromagnetic Calorimeter (EMC) for the PANDA target spectrometer. The EMC has been designed to meet the physics goals of the PANDA experiment. The performance figures are based on extensive prototype tests and radiation hardness studies. The document shows that the EMC is ready for construction up to the front-end electronics interface
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