2,918 research outputs found

    Modelling tidal energy extraction in a depth-averaged coastal domain

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    An extension of actuator disc theory is used to describe the properties of a tidal energy device, or row of tidal energy devices, within a depth-averaged numerical model. This approach allows a direct link to be made between an actual tidal device and its equivalent momentum sink in a depth-averaged domain. Extended actuator disc theory also leads to a measure of efficiency for an energy device in a tidal stream of finite Froude number, where efficiency is defined as the ratio of power extracted by one or more tidal devices to the total power removed from the tidal stream. To demonstrate the use of actuator disc theory in a depth-averaged model, tidal flow in a simple channel is approximated using the shallow water equations and the results are compared with the published analytical solutions. © 2010 © The Institution of Engineering and Technology

    Disease-Associated Mutations Disrupt Functionally Important Regions of Intrinsic Protein Disorder

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    The effects of disease mutations on protein structure and function have been extensively investigated, and many predictors of the functional impact of single amino acid substitutions are publicly available. The majority of these predictors are based on protein structure and evolutionary conservation, following the assumption that disease mutations predominantly affect folded and conserved protein regions. However, the prevalence of the intrinsically disordered proteins (IDPs) and regions (IDRs) in the human proteome together with their lack of fixed structure and low sequence conservation raise a question about the impact of disease mutations in IDRs. Here, we investigate annotated missense disease mutations and show that 21.7% of them are located within such intrinsically disordered regions. We further demonstrate that 20% of disease mutations in IDRs cause local disorder-to-order transitions, which represents a 1.7–2.7 fold increase compared to annotated polymorphisms and neutral evolutionary substitutions, respectively. Secondary structure predictions show elevated rates of transition from helices and strands into loops and vice versa in the disease mutations dataset. Disease disorder-to-order mutations also influence predicted molecular recognition features (MoRFs) more often than the control mutations. The repertoire of disorder-to-order transition mutations is limited, with five most frequent mutations (R→W, R→C, E→K, R→H, R→Q) collectively accounting for 44% of all deleterious disorder-to-order transitions. As a proof of concept, we performed accelerated molecular dynamics simulations on a deleterious disorder-to-order transition mutation of tumor protein p63 and, in agreement with our predictions, observed an increased α-helical propensity of the region harboring the mutation. Our findings highlight the importance of mutations in IDRs and refine the traditional structure-centric view of disease mutations. The results of this study offer a new perspective on the role of mutations in disease, with implications for improving predictors of the functional impact of missense mutations

    Imagery Reduces Feelings of Social Anxiety in a Healthy Population

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    Abstract Negative mental imagery has been shown to be involved in the onset and maintenance of numerous clinical disorders and as a result there has been growing scientific study of the therapeutic role of positive mental imagery, with studies reporting favourable results. However, with regard to social anxiety (SA) disorder the conventional approach to induce positive mental imagery has been suggested to be too demanding due to impairment in the retrieval of such episodes. Therefore, researchers have called for controlled studies to explore alternative inducement techniques with specific focus upon future orientated methods (a method more suitable for patients with SA). In the current study, we compare the conventional inducement technique (past) to a future orientated inducement technique (future) and a control condition (no imagery) and measure the impact upon selfreported levels of anxiety in a non-clinical population. Seventy-Eight younger students were randomly allocated to one of the two imagery inducement techniques or the control condition (and completed anxiety scales before and after imagery inducement or control task). To capture situational anxiety, phobia and broader short and long term (state versus trait) dysfunction the Liebowitz Social Anxiety Scale and State-Trait Anxiety Inventory were the chosen measures. Results confirmed that positive mental imagery reduces feelings of anxiety and demonstrated, for the first time, the effectiveness of a hypothetical future orientated technique to induce positive mental imagery. These data will provide the groundwork for intervention development in clinical populations with known difficulties capitalising on past based mental imagery

    The effect of signal acquisition and processing choices on ApEn values: Towards a “gold standard” for distinguishing effort levels from isometric force records

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    Approximate Entropy (ApEn) is frequently used to identify changes in the complexity of isometric force records with ageing and disease. Different signal acquisition and processing parameters have been used, making comparison or confirmation of results difficult. This study determined the effect of sampling and parameter choices by examining changes in ApEn values across a range of submaximal isometric contractions of the First Dorsal Interosseus. Reducing the sample rate by decimation changed both the value and pattern of ApEn values dramatically. The pattern of ApEn values across the range of effort levels was not sensitive to the filter cut-off frequency, or the criterion used to extract the section of data for analysis. The complexity increased with increasing effort levels using a fixed ‘r’ value (which accounts for measurement noise) but decreased with increasing effort level when ‘r’ was set to 0.1 of the standard deviation of force. It is recommended isometric force records are sampled at frequencies >200 Hz, template length (‘m’) is set to 2, and 'r' set to measurement system noise or 0.1 SD depending on physiological process to be distinguished. It is demonstrated that changes in ApEn across effort levels are related to changes in force gradation strategy

    Concept Store #2: Possible, Probable and Preferable Futures

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    Possible, Probable and Preferable Futures Launched in 2008 and running to three volumes Concept Store reflects on Arnolfini’s programme, as well as wider concerns providing a discursive space for commissioned texts, artists’ contributions, interviews and experiment. Issue 2 includes contributions by Heiremans & Vermeir, Francesc Ruiz, Graham Gussin, Herman Chong, Tommy Stockel, Marjolin Dijkman, Neil Cummings & Marysia Lewandowsa, Dieter Roelstraate, Max Gane, Bifo, Richard Grussin, Will Holder, Mark von Schlegell, Laura Oldfield Ford, Liu Ding, Geoff Cox, Nav Haq, Tom Trevor, Metahaven, Kianoosh vahebi and Cher Potter Published under a copyleft licenc

    Terahertz frequency quantum cascade lasers for use as waveguide-integrated local oscillators

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    Since their first demonstration in 2002, the performance of terahertz frequency quantum cascade lasers has developed extremely rapidly. We consider the potential use of terahertz frequency quantum cascade lasers as local oscillators in satellite-borne instrumentation for future Earth observation and planetary science missions. A specific focus will be on the development of compact, waveguide-integrated, heterodyne detection systems for the supra-terahertz range

    Scientific, institutional and personal rivalries among Soviet geographers in the late Stalin era

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    Scientific, institutional and personal rivalries between three key centres of geographical research and scholarship (the Academy of Sciences Institute of Geography and the Faculties of Geography at Moscow and Leningrad State Universities) are surveyed for the period from 1945 to the early 1950s. It is argued that the debates and rivalries between members of the three institutions appear to have been motivated by a variety of scientific, ideological, institutional and personal factors, but that genuine scientific disagreements were at least as important as political and ideological factors in influencing the course of the debates and in determining their final outcome
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