644 research outputs found

    Effect of control surface mass unbalance on the stability of a closed-loop active control system

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    The effects on stability of inertial forces arising from closed-loop activation of mass-unbalanced control surfaces are studied analytically using inertial energy approach, similar to the aerodynamic energy approach used for flutter suppression. The limitations of a single control surface like a leading-edge (LE) control or a trailing-edge (TE) control are demonstrated and compared to the superior combined LE-TE mass unbalanced system. It is shown that a spanwise section for sensor location can be determined which ensures minimum sensitivity to the mode shapes of the aircraft. It is shown that an LE control exhibits compatibility between inertial stabilization and aerodynamic stabilization, and that a TE control lacks such compatibility. The results of the present work should prove valuable, both for the purpose of flutter suppression using mass unbalanced control surfaces, or for the stabilization of structural modes of large space structures by means of inertial forces

    Machine-learning-based calving prediction from activity, lying, and ruminating behaviors in dairy cattle

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    The objective of this study was to use automated activity, lying, and rumination monitors to characterize prepartum behavior and predict calving in dairy cattle. Data were collected from 20 primiparous and 33 multiparous Holstein dairy cattle from September 2011 to May 2013 at the University of Kentucky Coldstream Dairy. The HR Tag (SCR Engineers Ltd., Netanya, Israel) automatically collected neck activity and rumination data in 2-h increments. The IceQube (IceRobotics Ltd., South Queensferry, United Kingdom) automatically collected number of steps, lying time, standing time, number of transitions from standing to lying (ly-. ing bouts), and total motion, summed in 15-min increments. IceQube data were summed in 2-h increments to match HR Tag data. All behavioral data were collected for 14 d before the predicted calving date. Retrospective data analysis was performed using mixed linear models to examine behavioral changes by day in the 14 d before calving. Bihourly behavioral differences from baseline values over the 14 d before calving were also evaluated using mixed linear models. Changes in daily rumination time, total motion, lying time, and lying bouts occurred in the 14 d before calving. In the bihourly analysis, extreme values for all behaviors occurred in the final 24 h, indicating that the monitored behaviors may be useful in calving prediction. To determine whether technologies were useful at predicting calving, random forest, linear discriminant analysis, and neural network machine -learning techniques were constructed and implemented using R version 3.1.0 (R Foundation for Statistical Computing, Vienna, Austria). These methods were used on variables from each technology and all combined variables from both technologies. A neural network analysis that combined variables from both technologies at the daily level yielded 100.0% sen-sitivity and 86.8% specificity. A neural network analysis that combined variables from both technologies in bihourly increments was used to identify 2-h periods in the 8 h before calving with 82.8% sensitivity and 80.4% specificity. Changes in behavior and machine-learning alerts indicate that commercially marketed behavioral monitors may have calving prediction potential

    Natural and cultural heritage in mountain landscapes: towards an integrated valuation

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    Mountain areas of Europe have been managed by humans for a long time, leading to a prevalence of semi-natural habitats in mountain landscapes today. These landscapes contain both natural and cultural heritage; however, natural and cultural heritage are rarely considered together when valuing landscapes and developing management plans in protected areas. Here we present a case study of seven protected areas in the mountains of Great Britain and Norway. We take a long-term perspective on landscape and land-use change and propose an integrated model of landscape valuation on the basis of combined natural and cultural heritage. Our model plots indicators of natural and cultural heritage along a gradient of land-use intensity, allowing simultaneous assessment and highlighting how valuation depends on what type of heritage is considered. We show that while contemporary land-use changes follow similar trajectories in Norway and Britain, different land-use histories mean that the loss of heritage differs between the regions. The model presented here thus allows for the consolidation of valuation based on both cultural and natural heritage in landscapes.publishedVersio

    Impacts of Climate Change on indirect human exposure to pathogens and chemicals from agriculture

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    Objective: Climate change is likely to affect the nature of pathogens and chemicals in the environment and their fate and transport. Future risks of pathogens and chemicals could therefore be very different from those of today. In this review, we assess the implications of climate change for changes in human exposures to pathogens and chemicals in agricultural systems in the United Kingdom and discuss the subsequent effects on health impacts. Data sources: In this review, we used expert input and considered literature on climate change ; health effects resulting from exposure to pathogens and chemicals arising from agriculture ; inputs of chemicals and pathogens to agricultural systems ; and human exposure pathways for pathogens and chemicals in agricultural systems. Data synthesis: We established the current evidence base for health effects of chemicals and pathogens in the agricultural environment ; determined the potential implications of climate change on chemical and pathogen inputs in agricultural systems ; and explored the effects of climate change on environmental transport and fate of different contaminant types. We combined these data to assess the implications of climate change in terms of indirect human exposure to pathogens and chemicals in agricultural systems. We then developed recommendations on future research and policy changes to manage any adverse increases in risks. Conclusions: Overall, climate change is likely to increase human exposures to agricultural contaminants. The magnitude of the increases will be highly dependent on the contaminant type. Risks from many pathogens and particulate and particle-associated contaminants could increase significantly. These increases in exposure can, however, be managed for the most part through targeted research and policy changes

    Curvature correction to the mobility of fluid membrane inclusions

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    For the first time, using rigorous low-Reynolds-number hydrodynamic theory on curved surfaces via a Stokeslet-type approach, we provide a general and concise expression for the leading-order curvature correction to the canonical, planar, Saffman-Delbrück value of the diffusion constant for a small inclusion embedded in an arbitrarily (albeit weakly) curved fluid membrane. In order to demonstrate the efficacy and utility of this wholly general result, we apply our theory to the specific case of calculating the diffusion coefficient of a locally curvature inducing membrane inclusion. By including both the effects of inclusion and membrane elasticity, as well as their respective thermal shape fluctuations, excellent agreement is found with recently published experimental data on the surface tension dependent mobility of membrane bound inclusions

    Properties of odd nuclei and the impact of time-odd mean fields: A systematic Skyrme-Hartree-Fock analysis

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    We present a systematic analysis of the description of odd nuclei by the Skyrme-Hartree-Fock approach augmented with pairing in BCS approximation and blocking of the odd nucleon. Current and spin densities in the Skyrme functional produce time-odd mean fields (TOMF) for odd nuclei. Their effect on basic properties (binding energies, odd-even staggering, separation energies and spectra) is investigated for the three Skyrme parameterizations SkI3, SLy6, and SV-bas. About 1300 spherical and axially-deformed odd nuclei with 16 < Z < 92 are considered. The calculations demonstrate that the TOMF effect is generally small, although not fully negligible. The influence of the Skyrme parameterization and the consistency of the calculations are much more important. With a proper choice of the parameterization, a good description of binding energies and their differences is obtained, comparable to that for even nuclei. The description of low-energy excitation spectra of odd nuclei is of varying quality depending on the nucleus

    The role of evidence-based guidelines in the diagnosis and treatment of functional neurological disorder

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    Evidence-based clinical practice guidelines, based on systematic reviews of existing evidence, play an important role in improving and standardizing the quality of patient care in many medical and psychiatric disorders, and could play an important role in the diagnosis and treatment of functional seizures and other functional neurological disorder (FND) subtypes. There are several reasons to think that evidence-based guidelines might be especially beneficial for the management of FND. In particular, the interdisciplinary and multidisciplinary teamwork necessary for the care of people with FND, the current lack of formal clinical training in FND, and the rapidly expanding body of evidence relating to FND all make guidelines based on systematic literature reviews especially valuable. In this perspective piece, we review clinical practice guidelines, their advantages and limitations, the reasons why evidence-based guidelines might be especially beneficial in the diagnosis and treatment of FND, and the steps that must be taken to create such guidelines for FND. We propose that professional organizations such as the American Academy of Neurology and the American Psychiatric Association undertake guideline development, ideally to create a co-authored or jointly endorsed set of guidelines that can set standards for interdisciplinary care for neurologists and mental health clinicians alike
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