6,975 research outputs found

    Towards mechanomagnetics in elastic crystals: insights from [Cu(acac)2_2]

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    We predict that the magnetic properties of \cuacac, an elastically flexible crystal, change dramatically when the crystal is bent. We find that unbent \cuacac\ is an almost perfect Tomonaga-Luttinger liquid. Broken-symmetry density functional calculations reveal that the magnetic exchange interactions along the chains is an order of magnitude larger than the interchain exchange. The geometrically frustrated interchain interactions cannot magnetically order the material at any experimentally accessible temperature. The ordering temperature (TNT_N), calculated from the chain random phase approximation, increases by approximately 24 orders of magnitude when the material is bent. We demonstrate that geometric frustration both suppresses TNT_N and enhances the sensitivity of TNT_N to bending. In \cuacac, TNT_N is extremely sensitive to bending, but remains too low for practical applications, even when bent. Partially frustrated materials could achieve the balance of high TNT_N and good sensitivity to bending required for practical applications of mechanomagnetic elastic crystals

    Milking the region? South African capital and Zambia’s dairy industry

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    Intelligent and adaptive tutoring for active learning and training environments

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    Active learning facilitated through interactive and adaptive learning environments differs substantially from traditional instructor-oriented, classroom-based teaching. We present a Web-based e-learning environment that integrates knowledge learning and skills training. How these tools are used most effectively is still an open question. We propose knowledge-level interaction and adaptive feedback and guidance as central features. We discuss these features and evaluate the effectiveness of this Web-based environment, focusing on different aspects of learning behaviour and tool usage. Motivation, acceptance of the approach, learning organisation and actual tool usage are aspects of behaviour that require different evaluation techniques to be used

    A METHOD TO QUANITIFY MOVEMENT VARIABILITY OF HIGHLY SKILLED GOLFERS PERFORMING DRIVER SWINGS

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    Variability has been described as inherent in the golf swing (Bradshaw et al., 2009), yet its impact on outcome is not understood. It is necessary to quantify the levels of movement variability before this relationship can be examined effectively. Thus, the aim of this study was to develop a method to quantify movement variability of golfers performing driver swings. 16 highly skilled golfers each performed 10 swings wearing retro reflective markers which were tracked by a 3D motion analysis system operating at 400Hz. Movement variability was calculated for each marker using scalene ellipsoid volume methods; a score representative of the 3D variability over 10 trials was then calculated. The variability levels calculated using this method showed increasing variability from the closed end of the chain (malleoli) to the open end of the chain (wrists)

    THE CREATION AND VALIDATION OF A LARGE-SCALE COMPUTER MODEL OF THE GOLF SWING

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    The aim of this study was to create and validate a full-body musculoskeletal model of a golfer performing a swing with their driver club. An elite female participant performed ten shots with her driver while wearing retro-reflective markers. An optical 3-D 6-camera system captured the kinematics of the markers at 400 Hz on the participant for each trial. A launch monitor device recorded the ball and club head conditions at impact. The kinematic data from one representative trial was selected to drive inverse and forward dynamics simulations of the created model. The validation results showed a very high level of agreement between experimental and simulated trajectories for selected markers (mean r = 0.966

    THE EFFECT OF THE APPLICATION OF DIFFERENT LEVELS OF MOVEMENT VARIABILITY ON MOVEMENT OUTCOME

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    The aim of this study was to assess the effect of the application of a previously validated golfer computer model on different levels of movement variability relative to a shot outcome measure: club head velocity. Movement variability was applied to the computer model on six measures sequentially throughout the body of the computer model. Four different levels of variability, 25%, 50%, 75% and 100% variability, were applied to x, y and z positional data of the aforementioned measures. Simulations were then performed with ADAMS/LifeMOD software for each level of movement variability applied to the measures in question. Club head velocity was measured during the simulation. The results suggest that movement variability application at these landmarks does not have an effect on outcome. These results potentially have implications for the coaching of the participant

    Social Values Related to the Development of Health and Care Guidance: Literature review for NICE by its Research Support Unit. Report of the Research Support Unit for the National Institute for Health and Care Excellence

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    The National Institute for Health and Care Excellence develops guidance for the allocation of resources for services in clinical and public health and social care. It has a policy of social values underpinning this work that was last updated in 2008. This report is of a review of the literature on social values to help inform the further updating of this policy. The review involved a semi iterative search for literature that was then screened for ideas relevant to health and care guidance. These ideas and the main issues they raise are reported under eight major social value categories. Twenty one themes arising from the review are also provided. The literature raises many issues about the nature of social values that can be applied to guidance development. It needs to be emphasized that not all of these issues should necessarily be applied to guidance development. They are simply issues that have been raised in the literature and this review provides an opportunity for them to be considered. Many of the ideas that have been proposed are in tension with each other and could not all be achieved. It should also be emphasized that many of the issues raise considerable practical challenges in terms of methods, data and financial and timeliness. The review does not assume that any of these issues or ideas could or should necessarily be part of NICE’s policy on social values in guidance production. The review simply provides a list of ideas, issues and themes from the literature for consideration

    Is attending a mental process?

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    The nature of attention has been the topic of a lively research programme in psychology for over a century. But there is widespread agreement that none of the theories on offer manage to fully capture the nature of attention. Recently, philosophers have become interested in the debate again after a prolonged period of neglect. This paper contributes to the project of explaining the nature of attention. It starts off by critically examining Christopher Mole’s prominent “adverbial” account of attention, which traces the failure of extant psychological theories to their assumption that attending is a kind of process. It then defends an alternative, process-based view of the metaphysics of attention, on which attention is understood as an activity and not, as psychologists seem to implicitly assume, an accomplishment. The entrenched distinction between accomplishments and activities is shown to shed new light on the metaphysics of attention. It also provides a novel diagnosis of the empirical state of play

    A Collective Route to Head and Neck Cancer Metastasis

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    © 2018 The Author(s). Distant metastasis (DM) from head and neck cancers (HNC) portends a poor patient prognosis. Despite its important biological role, little is known about the cells which seed these DM. Circulating tumour cells (CTCs) represent a transient cancer cell population, which circulate in HNC patients' peripheral blood and seed at distant sites. Capture and analysis of CTCs offers insights into tumour metastasis and can facilitate treatment strategies. Whilst the data on singular CTCs have shown clinical significance, the role of CTC clusters in metastasis remains limited. In this pilot study, we assessed 60 treatment naïve HNC patients for CTCs with disease ranging from early to advanced stages, for CTC clusters utilizing spiral CTC enrichment technology. Single CTCs were isolated in 18/60-30% (Ranging from Stage I-IV), CTC clusters in 15/60-25% (exclusively Stage IV) with 3/15-20% of CTC clusters also containing leukocytes. The presence of CTC clusters associated with the development of distant metastatic disease(P = 0.0313). This study demonstrates that CTC clusters are found in locally advanced patients, and this may be an important prognostic marker. In vivo and in vitro studies are warranted to determine the role of these CTC clusters, in particular, whether leukocyte involvement in CTC clusters has clinical relevance

    Reconstructing 3D x-ray CT images of polymer gel dosimeters using the zero-scan method

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    In this study x-ray CT has been used to produce a 3D image of an irradiated PAGAT gel sample, with noise-reduction achieved using the ‘zero-scan’ method. The gel was repeatedly CT scanned and a linear fit to the varying Hounsfield unit of each pixel in the 3D volume was evaluated across the repeated scans, allowing a zero-scan extrapolation of the image to be obtained. To minimise heating of the CT scanner’s x-ray tube, this study used a large slice thickness (1 cm), to provide image slices across the irradiated region of the gel, and a relatively small number of CT scans (63), to extrapolate the zero-scan image. The resulting set of transverse images shows reduced noise compared to images from the initial CT scan of the gel, without being degraded by the additional radiation dose delivered to the gel during the repeated scanning. The full, 3D image of the gel has a low spatial resolution in the longitudinal direction, due to the selected scan parameters. Nonetheless, important features of the dose distribution are apparent in the 3D x-ray CT scan of the gel. The results of this study demonstrate that the zero-scan extrapolation method can be applied to the reconstruction of multiple x-ray CT slices, to provide useful 2D and 3D images of irradiated dosimetry gels
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