20,330 research outputs found

    An investigation of the optimum design and flight of rockets

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    Variational methods for determining optimum design and flight of rocket

    Statistics of Bubble Rearrangements in a Slowly Sheared Two-dimensional Foam

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    Many physical systems exhibit plastic flow when subjected to slow steady shear. A unified picture of plastic flow is still lacking; however, there is an emerging theoretical understanding of such flows based on irreversible motions of the constituent ``particles'' of the material. Depending on the specific system, various irreversible events have been studied, such as T1 events in foam and shear transformation zones (STZ's) in amorphous solids. This paper presents an experimental study of the T1 events in a model, two-dimensional foam: bubble rafts. In particular, I report on the connection between the distribution of T1 events and the behavior of the average stress and average velocity profiles during both the initial elastic response of the bubble raft and the subsequent plastic flow at sufficiently high strains

    Measuring the determinants and barriers to physical activity for older people

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    Objective: Despite a recent focus upon the promotion of walking owing to its physical and mental health benefits, there is no appropriate measure that explores the determinants and barriers of walking for older people. Method: Interviews were conducted with 19 older people to generate an initial item pool, which was supplemented with relevant literature. A preliminary scale was developed, with a two-part preliminary piloting procedure that reviewed the initial items and domains. Results: The preliminary measure contained 73 initial items and 15 proposed initial domains. The development procedure suggested that the measure has acceptable face and content validity. These stages resulted in the development of the Determinants and Barriers to Walking for Older People Scale (DABWOP-S). Conclusions: Following a future psychometric evaluation, it is hoped that the DABWOP-S will result in a greater understanding of the determinants to walking for older people to shape social prescribing practices and walking programmes

    A PARAMETRIC INVESTIGATION OF THE LUNAR-ORBIT-RENDEZVOUS SCHEME

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    Lunar orbit rendezvous scheme - mission analysi

    Development of a transferable package of capacity and demand training to empower front-line staff to use change tools and techniques, informed by data, to improve their patient flows.

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    The purpose of this project was to develop an approach to training for the National Leadership and Innovation Agency for Healthcare (NLIAH) that could be applied across the NHS in Wales to increase understanding at a local level of capacity and demand interactions. Through an action research approach a transferable package of capacity and demand training was developed. This aimed to empower front-line staff to employ change tools and techniques informed by data when undertaking improvement projects. This constituted part of the NLIAH Skills4Change programme: an improvement course for front-line staff which combines blended learning with practical action for improvement. An analysis of questionnaire responses by former NLIAH capacity and demand training delegates identified the potential barriers to its application and its current wide-ranging use. These barriers were perceived as ‘access to information’; ‘no time to complete this project’ and ‘extra work on my current role’. Application of the tools was largely evidenced in outpatient and inpatient departments. The action research project built upon these findings, testing the barriers in a therapeutic setting. This highlighted the differences in applying these tools in a more complex service provision area. From the two threads of this research: questionnaire analysis and action research project, there are key elements which can be utilised to form recommendations for future employment of the package of training by NLIAH. The presence of an external facilitator during the action research project, alongside management support was identified as crucial to the momentum of this work. The ‘empowerment with support’ model this provided ensured sustainability of the improvements implemented. However, it was evident throughout the project and from the questionnaire responses, that organisational and service specific delivery of these tools is essential. Tools, methods and strategies for implementation are where the Skills4Change training programme traditionally focuses, with a mixed service delivery. The findings from this research suggest that to ensure maximum benefit and sustainability the tools and techniques need to be made real and relevant to the training participants. They need to see improvement in action and experience the benefits of the changes they are making. Linking the training with an understanding of the organisational culture will enhance this. Staff will be empowered to continue to change their services for improvement, as they witness the support from the organisation in which they operate

    Early increases in plasminogen activator activity following partial hepatectomy in humans

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    Background Increases in urokinase-like plasminogen activator (uPA) activity are reported to be amongst the earliest events occurring in remnant liver following partial hepatectomy in rats, and have been proposed as a key component of the regenerative response. Remodelling of the extracellular matrix, conversion of single chain hepatocyte growth factor to the active two-chain form and a possible activation of a mitogenic signalling pathway have all been ascribed to the increased uPA activity. The present study aimed to determine whether similar early increases in uPA activity could be detected in the remnant liver following resection of metastatic tumours in surgical patients. Results Eighteen patients undergoing partial hepatectomy for the removal of hepatic metastases secondary to primary colonic tumours were studied. Increased plasminogen activator activity was found in the final liver samples for the group of patients in whom the resection size was at least 50%. For smaller resections, the increased activity was not observed. The increased activity did not correlate with the age of the patient or with the time between the start of resection and the end of the operation. There was, however, a negative correlation between plasminogen activator activity and the time for which blood supply to the liver was clamped. Conclusions Our findings are in accordance with those from experimental animal models and show, for the first time, that rapid increases in plasminogen activator activity can occur following similarly large liver resection in humans. Thus, increases in plasminogen activator activity are an early event in the remnant liver following major liver resection in man. Our observations provide support for the contention that increases in plasminogen activators play a key role in the initiation of hepatic regeneration in man
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