12,210 research outputs found

    Using On-Line Quizzes to Help Students Learn Probability and Statistics

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    Online quizzes can be an effective and flexible means of helping learners develop key skills in probability and statistics. Quizzes give instant feedback, to help reinforce correct understanding and eliminate fundamental errors at an early stage in learning. We will describe our experience of designing and using quizzes with non-specialist and specialist students, on several different platforms including, most recently, Moodle. We describe Model Choice, a tool that helps students identify from a brief scenario the standard family of probability distributions they should work with to solve a problem. We will emphasize key design aspects of a successful quiz system, such as the importance of giving informative feedback to the learner. Using a standard platform, such as Moodle, is likely to require some compromise on design principles but building a stand-alone system to implement ideal design choices is very time-consuming

    Estimation of Bearing Forces in Rotating Machinery: A Problem Revisited

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    Development of a new ship machinery installation may require combinations of prime movers, electric motors, generators, gearboxes and other items that have not been used previously. Large items of this type are expensive to develop, so that only existing production items are likely to be affordable. Modern quiet ship design requires careful attention to the source characteristics of the individual machinery items as well as the dynamic characteristics of any new combination, so that fluctuating forces transmitted to the hull via mounting systems and flexible connectors in the final installation are within acceptable limits. Almost periodic components, which arise at multiples of machine rotational frequency, are of particular concern. Machine source properties are often known only in terms of the vibration characteristics of previous installations, not in terms of the disturbing forces that cause that vibration. The aim of the techniques described in this paper is to allow deduction of those disturbing forces from a matrix of transfer functions at each frequency of interest, measured with an existing machine in operation. The number of forces to be estimated must be less than the number of structural degrees of freedom. Those degrees of freedom arise from rigid body motions and machine flexural properties, which may change significantly when shafts are rotating. Also, the matrices must be redundant in order to allow estimation of the accuracy of derived force estimates. The larger the machine, the greater the number of degrees of freedom that are likely to arise at a given frequency. A first use of the methodology was to establish the bearing forces in a marine turbo generator (TG) set with plain journal bearings. Measurements of transfer functions were made with the machine stationary and then with the machine in normal operation. Direct and reciprocal measurements in different directions were made for a large number of locations on the machine structure and bearings, covering the frequency range up to more than twice shaft rotational frequency. There were large differences in some frequency ranges between the static and operational conditions. Vibration due to machine operation was then measured to allow deduction of bearing forces using the transfer function matrices. Repeat measurements were made to establish whether machine source properties changed significantly with time, while statistical techniques were also used to identify and eliminate any suspect measurements. Those early experiments are described in this paper with a view to future application of similar techniques

    Robust Reform: Implementing robust institutional arrangements to achieve efficient water use in Australia

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    The focus of this report is on implementing institutional arrangements for the efficient allocation and management of water. Water is an input into human use including economic production and recreation activities that generate many externalities. It also provides many valuable ecosystem services only partially captured in the market. Institutional arrangements are required that are dynamically efficient and low cost, and robust enough to withstand the test of time. Robust administrative arrangements are characterised by the lack of a need for change.water reform;institutional;trading;Australia

    Robust Separation:A search for a generic framework to simplify registration and trading of interests in natural resources

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    This report is about the search for an economically efficient and equitable system of defining, allocating, and managing use of natural resources that proves to be robust. Robust in the sense that the fundamental principles and foundations upon which it is based remains unchanged over time. We focus on the notion of “interests” in natural resources, and obligations associated with use. We search for a generic robust approach to the definition of interests, rights and use obligations that sits comfortably within an economically efficient trading system. Pricing and charging issues and the question of how to convert from existing systems to the proposed one are left for subsequent reports.audit;Australia;natural resource management

    The Experience of Teaching Statistics to Non-Specialist Students in Saudi Universities: The Role of Technology and Language

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    The importance of statistics is not limited to statisticians but also impacts on non-statisticians who have to use statistics. One important issue is how statistics is best taught to, and learned by, non-specialist students. The pervasive use of the English language causes additional challenges to learners whose first language is not English, especially when technological resources that use English language, such as statistics software packages, are an integral part of the course. This paper presents research into the current position in Saudi universities, where there has previously been a lack of research into this topic. Mixed methods research has been used: a questionnaire survey of 1,053 students and qualitative interviews with 16 teachers of statistics from all colleges within all six universities where statistics is taught to non-specialist students in Saudi Arabia’s Eastern Region. This presentation will discuss differences between the experiences of learners taught in the Arabic and English languages

    Identifying the unique characteristics of independent fashion retailers in Scotland by utilising Porter’s generic competitive strategy model and the marketing mix

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    Independent retailers in the fashion sector make a substantial contribution to the UK economy at the time of significant change on the high street due to financial pressures and the growth of online trade. They provide an element of creativity and innovation to a homogenous retail landscape. The independent fashion retailer creates a destination and individual identity by presenting a unique offering and differentiated experience. Whilst independent retailers are important to the future of our high street, research is limited, particularly in the area of fashion independents. Therefore this research examines and identifies the unique characteristics of independent fashion retailers within Scotland. The research adopts a case study approach, qualitative methods of data collection in order to fulfil the aim and objectives of the study. Porter’s Generic Competitive Strategies and the marketing mix were utilised as a means of drawing out the individual aspects and unique characteristics of the independent fashion retailer.Los minoristas independientes en el sector de la moda hacen una contribución sustancial a la economía del Reino Unido en el momento de un cambio significativo debido a las presiones financieras y el crecimiento del comercio en línea. Proporcionan un elemento de creatividad e innovación a un paisaje minorista homogéneo. El distribuidor independiente de moda crea un destino y una identidad individual al presentar una oferta única y una experiencia diferenciada. Mientras que los minoristas independientes son importantes para el futuro, la investigación es limitada, sobre todo en el área de empresas independientes de la moda. Por lo tanto, esta investigación examina e identifica las características únicas de los minoristas independientes de moda en Escocia. La investigación adopta un enfoque de estudio de caso, métodos cualitativos de recolección de datos con el fin de cumplir con los objetivos del estudio. Las Estrategias Competitivas Generales de Porter y la mezcla de mercadeo se utilizaron como un medio de extraer los aspectos individuales y las características únicas del minorista de moda independiente

    Managing Change: Australian structural adjustment lessons for water

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    The purpose of this report is to search Australia's extensive experience in running and reviewing structural adjustment programs for insights of relevance to water reform.Water;Australia;Water reform;structural adjustment;rural;agricultural;policy.

    General Practitioners' perceptions of the route to evidence-based medicine: a questionnaire survey

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    Objectives: To determine the attitude of general practitioners towards evidence based medicine and their related educational needs. Design: A questionnaire study of general practitioners. Setting: General practice in the former Wessex region, England. Subjects: Randomly selected sample of 25% of all general practitioners (452), of whom 302 replied. Main outcome measures: Respondents' attitude towards evidence based medicine, ability to access and interpret evidence, perceived barriers to practising evidence based medicine, and best method of moving from opinion based to evidence based medicine. Results: Respondents mainly welcomed evidence based medicine and agreed that its practice improves patient care. They had a low level of awareness of extracting journals, review publications, and databases (only 40% knew of the Cochrane Database of Systematic Reviews), and, even if aware, many did not use them. In their surgeries 20% had access to bibliographic databases and 17% to the world wide web. Most had some understanding of the technical terms used. The major perceived barrier to practising evidence based medicine was lack of personal time. Respondents thought the most appropriate way to move towards evidence based general practice was by using evidence based guidelines or proposals developed by colleagues. Conclusion: Promoting and improving access to summaries of evidence, rather than teaching all general practitioners literature searching and critical appraisal, would be the more appropriate method of encouraging evidence based general practice. General practitioners who are skilled in accessing and interpreting evidence should be encouraged to develop local evidence based guidelines and advice

    Shallow landsliding and catchment connectivity within the Houpoto Forest, New Zealand.

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    Active landslides and their contribution to catchment connectivity have been investigated within the Houpoto Forest, North Island, New Zealand. The aim was to quantify the proportion of buffered versus coupled landslides and explore how specific physical conditions influenced differences in landslide connectivity. Landsliding and land use changes between 2007 and 2010 were identified and mapped from aerial photography, and the preliminary analyses and interpretations of these data are presented here. The data indicate that forest harvesting made some slopes more susceptible to failure, and consequently many landslides were triggered during subsequent heavy rainfall events. Failures were particularly widespread during two high magnitude (> 200 mm/day) rainfall events, as recorded in 2010 imagery. Connectivity was analysed by quantifying the relative areal extents of coupled and buffered landslides identified in the different images. Approximately 10 % of the landslides were identified as being coupled to the local stream network, and thus directly contributing to the sediment budget. Following liberation of landslides during high-magnitude events, low-magnitude events are thought to be capable of transferring more of this sediment to the channel. Subsequent re-planting of the slopes appears to have helped recovery by increasing the thresholds for failure, thus reducing the number of landslides during subsequent high-magnitude rainfall events. Associated with this is a reduction in slope-channel connectivity. These preliminary results highlight how site specific preconditioning, preparatory and triggering factors contribute to landslide distribution and connectivity, in addition to how efficient re-afforestation improves the rate of slope recovery
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