424 research outputs found

    Near Resonantly Enhanced Schlieren for Wake Flow Visualisation in Shock Tunnels

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    A new variant of the resonantly enhanced schlieren or shadowgraph technique has been developed for visualising flows with small density gradients using seeded lithium metal as the resonant species. The novelty of the technique lies in the use of a diode laser as the light source for the visualisation rather than systems based upon solid-state-pumped dye lasers or spectral lamps. We present time-resolved visualisations of near-wake flows around a cylinder in a hypersonic freestream in a shock tunnel, showing flow structures that cannot be resolved using a conventional standard schlieren system. Furthermore, a method of removing, at least partially, the limitation related to line-ofsight visualisation is demonstrated

    Wake Flows in Coastal Oceans: An Experimental Study of Topographic Effects

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    We consider the effects of coastal topography on the wake of an idealised headland model in a laboratory flume. Under a range of Reynolds numbers relevant to coastal oceans, we find that coherent eddies interact strongly with the headland shear layer and wake, affecting the width of the shear layer and the length of the wake. A preliminary investigation of turbulence statistics indicates that topography upstream of a headland can lead to a wider shear layer, a headland wake that extends further downstream, and enhanced horizontal diffusion out of the wake relative to the case with unperturbed oncoming flow

    Methods for the inclusion of real-world evidence in network meta-analysis

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    Background Network Meta-Analysis (NMA) is a key component of submissions to reimbursement agencies world-wide, especially when there is limited direct head-to-head evidence for multiple technologies from randomised controlled trials (RCTs). Many NMAs include only data from RCTs. However, real-world evidence (RWE) is also becoming widely recognised as a valuable source of clinical data. This study aims to investigate methods for the inclusion of RWE in NMA and its impact on the level of uncertainty around the effectiveness estimates, with particular interest in effectiveness of fingolimod. Methods A range of methods for inclusion of RWE in evidence synthesis were investigated by applying them to an illustrative example in relapsing remitting multiple sclerosis (RRMS). A literature search to identify RCTs and RWE evaluating treatments in RRMS was conducted. To assess the impact of inclusion of RWE on the effectiveness estimates, Bayesian hierarchical and adapted power prior models were applied. The effect of the inclusion of RWE was investigated by varying the degree of down weighting of this part of evidence by the use of a power prior. Results Whilst the inclusion of the RWE led to an increase in the level of uncertainty surrounding effect estimates in this example, this depended on the method of inclusion adopted for the RWE. ‘Power prior’ NMA model resulted in stable effect estimates for fingolimod yet increasing the width of the credible intervals with increasing weight given to RWE data. The hierarchical NMA models were effective in allowing for heterogeneity between study designs, however, this also increased the level of uncertainty. Conclusion The ‘power prior’ method for the inclusion of RWE in NMAs indicates that the degree to which RWE is taken into account can have a significant impact on the overall level of uncertainty. The hierarchical modelling approach further allowed for accommodating differences between study types. Consequently, further work investigating both empirical evidence for biases associated with individual RWE studies and methods of elicitation from experts on the extent of such biases is warranted

    Conducting retrospective impact analysis to inform a medical research charity’s funding strategies: The case of Asthma UK

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    © 2013 Hanney et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This article has been made available through the Brunel Open Access Publishing Fund.BACKGROUND: Debate is intensifying about how to assess the full range of impacts from medical research. Complexity increases when assessing the diverse funding streams of funders such as Asthma UK, a charitable patient organisation supporting medical research to benefit people with asthma. This paper aims to describe the various impacts identified from a range of Asthma UK research, and explore how Asthma UK utilised the characteristics of successful funding approaches to inform future research strategies. METHODS: We adapted the Payback Framework, using it both in a survey and to help structure interviews, documentary analysis, and case studies. We sent surveys to 153 lead researchers of projects, plus 10 past research fellows, and also conducted 14 detailed case studies. These covered nine projects and two fellowships, in addition to the innovative case studies on the professorial chairs (funded since 1988) and the MRC-Asthma UK Centre in Allergic Mechanisms of Asthma (the ‘Centre’) which together facilitated a comprehensive analysis of the whole funding portfolio. We organised each case study to capture whatever academic and wider societal impacts (or payback) might have arisen given the diverse timescales, size of funding involved, and extent to which Asthma UK funding contributed to the impacts. RESULTS: Projects recorded an average of four peer-reviewed journal articles. Together the chairs reported over 500 papers. All streams of funding attracted follow-on funding. Each of the various categories of societal impacts arose from only a minority of individual projects and fellowships. Some of the research portfolio is influencing asthma-related clinical guidelines, and some contributing to product development. The latter includes potentially major breakthroughs in asthma therapies (in immunotherapy, and new inhaled drugs) trialled by university spin-out companies. Such research-informed guidelines and medicines can, in turn, contribute to health improvements. The role of the chairs and the pioneering collaborative Centre is shown as being particularly important. CONCLUSIONS: We systematically demonstrate that all types of Asthma UK’s research funding assessed are making impacts at different levels, but the main societal impacts from projects and fellowships come from a minority of those funded. Asthma UK used the study’s findings, especially in relation to the Centre, to inform research funding strategies to promote the achievement of impact.This study was funded by Asthma UK

    Does police size matter?:A review of the evidence regarding restructuring police organisations

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    Restructuring and merging public sector organisations is often seen as a way to enhance efficiency and efficacy. There is ongoing debate about the impact of police force sizes, structures and mergers as police organisations attempt to adapt to reductions in their budgets and changes in patterns of criminality. The article reviews the evidence regarding key aspects of police reform: finding mixed evidence regarding the links between size and performance, while noting risks that mergers may impair local policing. The article discusses the impact of mergers on protective services, governance and accountability, while also discussing potential risks and opportunities associated with the merger process itself. The review finds significant gaps in the available evidence, and significant opportunities to expand the evidence base on this topic. Given current gaps in the evidence regarding size, efficacy and efficiency, it is important to give due consideration to symbolic and rhetorical aspects of mergers

    Efficacy and safety of once-daily fluticasone furoate 50 mcg in adults with persistent asthma: a 12-week randomized trial

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    Abstract Background Fluticasone furoate (FF) is a novel, once-daily inhaled corticosteroid (ICS) that has been shown to improve lung function vs. placebo in asthma patients. This study evaluated the efficacy and safety of FF 50 mcg compared with placebo in asthma patients uncontrolled by non-ICS therapy. Methods This 12-week, multicentre, randomized, double-blind, placebo-controlled, parallel-group, phase III study randomized 248 patients (aged ≥12 years) to once-daily FF 50 mcg administered via the ELLIPTA™a dry powder inhaler or placebo. The primary endpoint was change from baseline in pre-dose evening trough forced expiratory volume in one second (FEV1). Secondary endpoints were change from baseline in percentage of rescue-free 24-h periods (powered), evening and morning peak expiratory flow, symptom-free 24-h periods and withdrawals due to lack of efficacy. Other endpoints included Asthma Control Test™, Asthma Quality of Life Questionnaire and ELLIPTA ease of use questions. Safety was assessed throughout the study. Results There was a significant difference in evening trough FEV1 between FF 50 mcg and placebo (treatment difference: 120 mL; p = 0.012). There was also a significant difference in rescue-free 24-h periods (11.6%; p = 0.004) vs. placebo. There were numerically greater improvements with FF vs. placebo for all remaining secondary endpoints. The incidence of adverse events was lower with FF (31%) than with placebo (38%); few were treatment-related (FF 50 mcg: n = 1, <1%; placebo: n = 4, 3%). Conclusion FF 50 mcg once daily significantly improved FEV1 and percentage of rescue-free 24-h periods experienced over 12 weeks vs. placebo, and was well tolerated. Trial registration www.clinicaltrials.gov , registration number: NCT0143607

    Inhaled corticosteroids and long-acting beta-agonists in adult asthma: a winning combination in all?

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    In the recent years, considerable insight has been gained in to the optimal management of adult asthma. Most adult patients with asthma have mild intermittent and persistent disease, and it is acknowledged that many patients do not reach full control of all symptoms and signs of asthma. Those with mild persistent asthma are usually not well controlled without inhaled corticosteroids (ICS). Studies have provided firm evidence that these patients can be well controlled when receiving ICS, especially when disease is of recent onset. This treatment should be given on a daily basis at a low dose and when providing a good response should be maintained to prevent severe exacerbations and disease deterioration. Intermittent ICS treatment at the time of an exacerbation has also been suggested as a strategy for mild persistent asthma, but it is less effective than low-dose regular treatment for most outcomes. Adding a long-acting beta-agonist (LABA) to ICS appears to be unnecessary in most of these patients for optimising control of their asthma. Patients with moderate persistent asthma can be regarded as those who are not ideally controlled on low-dose ICS alone. The combination of an ICS and LABA is preferred in these patients, irrespective of the brand of medicine, and this combination is better than doubling or even quadrupling the dose of ICS to achieve better asthma control and reduce exacerbation risks. An ICS/LABA combination in a single inhaler represents a safe, effective and convenient treatment option for the management of patients with asthma unstable on inhaled steroids alone. Ideally, once asthma is under full control, the dose of inhaled steroids should be reduced, which is possible in many patients. The duration of treatment before initiating this dose reduction has, however, not been fully established. One of the combinations available to treat asthma (budesonide and formoterol) has also been assessed as both maintenance and rescue therapy with a further reduction in the risk for a severe exacerbation. Clinical effectiveness in the real world now has to be established, since this approach likely improves compliance with regular maintenance therapy

    The evolution of the student as a customer in Australian higher education: a policy perspective

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    In 2014, the Australian Federal Government attempted to de-regulate higher education fees so as to allow universities to set their own tuition fees. The associated public debate offer critical insights into how the identity of a student as a ‘customer’ of higher education is understood and deployed when developing higher education policy. This paper uses the 2014 Australian higher education reforms as a lens through which to further scholarly research into the student-as-customer metaphor and to see how it is influenced by the perceptions and understandings of policy actors external to the higher education sector. These include politicians, special interest groups, the students and their parents and prospective employers. This study reveals that the public/private nexus—both of funding and benefit— problematizes traditional conceptualisations of students and others as higher education customers. In turn, this restricts the ability or desire of policy actors to describe how the student functions as a customer as a consequence of market reform. This inability compromises the development of effective and sustainable higher education polic
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