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    125254 research outputs found

    Randomised controlled trial and economic evaluation of a chest pain observation unit compared with routine care

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    Objectives To measure the effectiveness and cost effectiveness of providing care in a chest pain observation unit compared with routine care for patients with acute, undifferentiated chest pain. Design Cluster randomised controlled trial, with 442 days randomised to the chest pain observation unit or routine care, and cost effectiveness analysis from a health service costing perspective. Setting The emergency department at the Northern General Hospital, Sheffield, United Kingdom. Participants 972 patients with acute, undifferentiated chest pain (479 attending on days when care was delivered in the chest pain observation unit, 493 on days of routine care) followed up until six months after initial attendance. Main outcome measures The proportion of participants admitted to hospital, the proportion with acute coronary syndrome sent home inappropriately, major adverse cardiac events over six months, health utility, hospital reattendance and readmission, and costs per patient to the health service. Results Use of a chest pain observation unit reduced the proportion of patients admitted from 54% to 37% (difference 17%, odds ratio 0.50, 95% confidence interval 0.39 to 0.65, P < 0.001) and the proportion discharged with acute coronary syndrome from 14% to 6% (8%, –7% to 23%, P = 0.264). Rates of cardiac event were unchanged. Care in the chest pain observation unit was associated with improved health utility during follow up (0.0137 quality adjusted life years gained, 95% confidence interval 0.0030 to 0.0254, P = 0.022) and a saving of £78 per patient (–£56 to £210, P = 0.252). Conclusions Care in a chest pain observation unit can improve outcomes and may reduce costs to the health service. It seems to be more effective and more cost effective than routine care

    Subharmonic oscillation modeling and MISO Volterra series

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    Subharmonic generation is a complex nonlinear phenomenon which can arise from nonlinear oscillations, bifurcation and chaos. It is well known that single-input–single-output Volterra series cannot currently be applied to model systems which exhibit subharmonics. A new modeling alternative is introduced in this paper which overcomes these restrictions by using local multiple input single output Volterra models. The generalized frequency-response functions can then be applied to interpret systems with subharmonics in the frequency domain

    A binary neural k-nearest neighbour technique

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    K-Nearest Neighbour (k-NN) is a widely used technique for classifying and clustering data. K-NN is effective but is often criticised for its polynomial run-time growth as k-NN calculates the distance to every other record in the data set for each record in turn. This paper evaluates a novel k-NN classifier with linear growth and faster run-time built from binary neural networks. The binary neural approach uses robust encoding to map standard ordinal, categorical and real-valued data sets onto a binary neural network. The binary neural network uses high speed pattern matching to recall the k-best matches. We compare various configurations of the binary approach to a conventional approach for memory overheads, training speed, retrieval speed and retrieval accuracy. We demonstrate the superior performance with respect to speed and memory requirements of the binary approach compared to the standard approach and we pinpoint the optimal configurations

    No-moving-part hybrid-synthetic jet actuator

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    In contrast to usual synthetic jets, the “hybrid-synthetic jets” of non-zero timemean nozzle mass flow rate are increasingly often considered for control of flow separation and/or transition to turbulence as well as heat and mass transfer. The paper describes tests of a scaled-up laboratory model of a new actuator version, generating the hybrid-synthetic jets without any moving components. Self-excited flow oscillation is produced by aerodynamic instability in fixed-wall cavities. The return flow in the exit nozzles is generated by jet-pumping effect. Elimination of the delicate and easily damaged moving parts in the actuator simplifies its manufacture and assembly. Operating frequency is adjusted by the length of feedback loop path. Laboratory investigations concentrated on the propagation processes taking place in the loop

    The design of caring environments and the quality of life of older people

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    There has been little systematic research into the design of care environments for older people. This article reviews empirical studies from both the architectural and the psychological literature. It outlines the instruments that are currently available for measuring both the environment and the quality of life of older people, and it summarises the evidence on the layout of buildings, the sensory environment and the privacy of residents. The conclusion is drawn that all evidence-based design must be a compromise or dynamic and, as demands on the caring environment change over time, this compromise must be re-visited in the form of post-occupancy evaluation

    Characterising pressure and bruising in apple fruit

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    A large percentage of apples are wasted each year due to damage such as bruising. The apple journey from orchard to supermarket is very complex and apples are subjected to a variety of static and dynamic loads that could result in this damage occurring. The aim of this work was to use a novel ultrasonic technique to study apple contact areas and stresses under static loading that may occur, for example, in bulk storage bins used during harvesting. These results were used to identify load thresholds above which unacceptable damage occurs. They were also used to validate output from a finite element model, which will ultimately be developed into a packaging design tool to help reduce the likelihood of apple damage occurring

    Theoretical molecular rheology of branched polymers in simple and complex flows: the pom-pom model

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    The nonlinear rheological constitutive equation of a class of multiply branched polymers is derived using the tube model. The molecular architecture may be thought of as two q-arm stars connected by a polymeric ''crossbar.'' The dynamics lead to a novel integrodifferential equation which exhibits extreme strain hardening in extension and strain softening in shear. Calculations of flow through a contraction predict that the degree of long-chain branching controls the growth of corner vortices, in agreement with experiments on commercial branched polymers

    Further Studies of the Distributional Effects of Road Pricing

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    This Working Paper extends the study reported in Working Paper 400, which used the MVA START model for London, disaggregated into three income groups for each of car owners and non car owners, to investigate the distributional effects of road pricing in London. At the time of that study, it was not possible to obtain, from the disaggregate model, output on trips, flows and speeds. The further work reported in this Working Paper has involved extending the evaluation procedures to provide output on trips, flows and speeds; assessing the results from the previous study in tms of these indicators, and testing a fourth charging structure. In all, four charging structures were tested. It is concluded that the additional charging structure tested here, with the original LPAC charging structure, but with charging extended to the off peak in inner London, is by far the most effective in terms of overall benefits, and is similar in its distributional effects to the original LPAC structure

    A Simulator Based Evaluation of Speed Reduction Measures for Rural Arterial Roads

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    In Great Britain accident rates on rural roads are not falling as fast as those on urban roads. In 1993 the number of casualties from accidents on rural A roads was 4% higher than the average for 1981-85, which is the baseline for the Department of Transport target of a one third reduction in road accident casualties by the year 2000. Driving too fast for the conditions is a major factor in accident causation. High speeds in conjunction with the varying geometric conditions common on rural single-carriageway A roads, result in a fatal accident rate which is higher than that for any other type of road. The aim of the research was to investigate, in a safe and controlled manner using the University of Leeds Advanced Driving Simulator, the effectiveness of a variety of measures for reducing driver speeds on rural single-carriageway arterial roads, in order to identify practical and cost-effective combinations of treatments to reduce both the frequency and severity of accidents on such roads. Treatments appropriate to each of three situations were investigated. These were: (1) treatments that reduce speed and speed variance on fairly straight roads (general treatments); (2) treatments that reduce curve entry speeds for sharp bends; (3) treatments that reduce speeds on the approach to and through villages. Treatments investigated included the use of road markings to reduce lane width or produce horizontal deflection; the use of signs both on posts and on the road surface; and the use of optical illusions to affect the driver's perception of speed or road width. Many of the treatments have been used previously, but few have been evaluated in a controlled way. The first phase of the research involved the evaluation of each individual treatment. The treatments were evaluated with respect to their effect on speed, vehicle lateral position, and incidence of overtaking. The second phase of the research involved the evaluation of variations on and combinations of the most effective treatments. Substantial reductions in speeds were obtained by some of the treatments evaluated, for all three situations studied. There were also reductions in speed variance. These reductions are significant both in statistical and practical road safety terms. For the village situation the most effective combination of treatments was the chicane without hatching, yellow or white transverse lines throughout the village, and countdown speed limit signs on the approach to the village. For the bend treatments the most effective treatments were transverse lines with reducing spacing (including a central area filled with transverse lines); a central hatched area; a Wundt illusion (a series of chevrons with increasing angles but constant spacing, pointing towards the driver); and hatched areas at the edges of the road. Further speed reductions may be produced by combining one of the above treatments with the most effective sign treatments — SLOW or a triangular, warning sign style, advisory speed sign painted on the road surface. For the general treatments all those which involved lane narrowing produced speeds significantly different from the control. Shoulders delineated by continuous lines were more effective, than those delineated by broken lines. Shoulder width was not important, but carriageway width was. For central hatching, type of delineation and width of hatched area was not important. The location (central/edge) and type (removing carriageway or lane space) of the narrowing was not important

    Acoustic form in the Modern Movement

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    The architects of the Modern Movement in the late 1920s found new sources of form through the pursuit of technical and functional issues in design. They sought shaping agents in functional organization, in the admission of light, in efficiency of structure and construction, and many other physical issues of this kind. At the same time, they felt the need to escape from traditional rules of architectural composition involving Classical orders of columns, symmetry and axes. They were ready to discover a new and surprising identity for buildings precisely to defy the historicist conventions that until then dominated architecture as a cultural tradition. Acoustics is an area in which many interesting claims were made, and some famous Modernist designs were supposedly formed, or at very least inspired, by acoustic forces. These historical instances beg the question whether acoustics is really a legitimate and helpful formal determinant of buildings. Perhaps instead, the acoustic arguments put forward by architects to justify their formal choices were just convenient alibis. This is a far more complex issue than at first it seems


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