10,604 research outputs found

    Directional mass transport in an atmospheric pressure surface barrier discharge

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    In an atmospheric pressure surface barrier discharge the inherent physical separation between the plasma generation region and downstream point of application reduces the flux of reactive chemical species reaching the sample, potentially limiting application efficacy. This contribution explores the impact of manipulating the phase angle of the applied voltage to exert a level of control over the electrohydrodynamic forces generated by the plasma. As these forces produce a convective flow which is the primary mechanism of species transport, the technique facilitates the targeted delivery of reactive species to a downstream point without compromising the underpinning species generation mechanisms. Particle Imaging Velocimetry measurements are used to demonstrate that a phase shift between sinusoidal voltages applied to adjacent electrodes in a surface barrier discharge results in a significant deviation in the direction of the plasma induced gas flow. Using a two-dimensional numerical air plasma model, it is shown that the phase shift impacts the spatial distribution of the deposited charge on the dielectric surface between the adjacent electrodes. The modified surface charge distribution reduces the propagation length of the discharge ignited on the lagging electrode, causing an imbalance in the generated forces and consequently a variation in the direction of the resulting gas flow

    Composition chimique et indice de palatabilité des feuilles de Adenodolichos rhomboideus Leucaena leucocephala et Stylosanthes guianensis chez la chèvre locale à Lubumbashi

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    Cette expérience a été menée pour évaluer la composition chimique et l'appétence de A. rhomboideus, légumineuse moins connues qui peut avoir le potentiel d'être incluse dans l’alimentation des ruminants en saison sèche comme supplément de foin de faible qualité. La palatabilité du fourrage d’Adenodolichos rhomboideus (O. Hoffm) Harms a été testée en comparaison de celui de Leucaena leucocephala et de Stylosanthes guianensis. Un foin de graminées (Imperata cylindrica et Setaria palude-fusca) a été utilisé comme fourrage de référence. Cette étude a été menée selon la méthode dite « cafétéria » dont l’indice de palatabilité a été estimé en fonction de fourrage de foin selon la formule P = (Ti/Di)/ (T1/D1). Ti et Di sont les quantités de foin consommées et distribuées respectivement. T1 et D1 sont les quantités de légumineuses consommées et distribuées. Les teneurs moyennes en protéines brutes ont été de 100, 132 et 270g/kg MS respectivement pour Stylosanthes, Adenodolichos et Leucaena. Suivant l’indice de palatabilité, le fourrage de Leucaena a été le plus consommé. Les indices de palatabilité des fourrages de Stylosanthes et d’Adenodolichos ont été statistiquement semblables (p<0,05).  Adenodolichos rhomboideus présente une faible palatabilité, mais il contient des teneurs en protéines brutes supérieures à la limite  recommandée pour l’entretien des ruminants (80 g/kg MS) et supérieures à celle de S. guianensis.Mots clés : Caprins, appétibilité, légumineuses, saison sèche, Congo (RD), Adenodolichos rhomboideus

    Impact of motorboats on fish embryos depends on engine type

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    This is the final version of the article. Available from Oxford University Press via the DOI in this record.Human generated noise is changing the natural underwater soundscapes worldwide. The most pervasive sources of underwater anthropogenic noise are motorboats, which have been found to negatively affect several aspects of fish biology. However, few studies have examined the effects of noise on early life stages, especially the embryonic stage, despite embryo health being critical to larval survival and recruitment. Here, we used a novel setup to monitor heart rates of embryos from the staghorn damselfish (Amblyglyphidodon curacao) in shallow reef conditions, allowing us to examine the effects ofin situboat noise in context with real-world exposure. We found that the heart rate of embryos increased in the presence of boat noise, which can be associated with the stress response. Additionally, we found 2-stroke outboard-powered boats had more than twice the effect on embryo heart rates than did 4-stroke powered boats, showing an increase in mean individual heart rate of 1.9% and 4.6%, respectively. To our knowledge this is the first evidence suggesting boat noise elicits a stress response in fish embryo and highlights the need to explore the ecological ramifications of boat noise stress during the embryo stage. Also, knowing the response of marine organisms caused by the sound emissions of particular engine types provides an important tool for reef managers to mitigate noise pollution.Research was funded by the ARC Center of Excellence for Coral Reef Studies (EI140100117), an International Postgraduate Research Scholarship awarded to S.J.S. from James Cook University and a UK Natural Environment Research Council grant to S.D.S. (NE/P001572/1)

    Label-Dependencies Aware Recurrent Neural Networks

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    In the last few years, Recurrent Neural Networks (RNNs) have proved effective on several NLP tasks. Despite such great success, their ability to model \emph{sequence labeling} is still limited. This lead research toward solutions where RNNs are combined with models which already proved effective in this domain, such as CRFs. In this work we propose a solution far simpler but very effective: an evolution of the simple Jordan RNN, where labels are re-injected as input into the network, and converted into embeddings, in the same way as words. We compare this RNN variant to all the other RNN models, Elman and Jordan RNN, LSTM and GRU, on two well-known tasks of Spoken Language Understanding (SLU). Thanks to label embeddings and their combination at the hidden layer, the proposed variant, which uses more parameters than Elman and Jordan RNNs, but far fewer than LSTM and GRU, is more effective than other RNNs, but also outperforms sophisticated CRF models.Comment: 22 pages, 3 figures. Accepted at CICling 2017 conference. Best Verifiability, Reproducibility, and Working Description awar

    Modeling the thermalization of electrons in conditions relevant to atmospheric pressure He-O-2 nanosecond pulsed discharges

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    The electron thermalization process is significant in nanosecond pulsed discharges due to the applied voltage pulse’s short duration and rapid rise and fall times. In this contribution a comparison was made between two approaches to modeling the electron kinetics of electron thermalization in atmospheric pressure helium plasma with an oxygen admixture. Modeling based on the direct solution of the local time-dependent electron Boltzmann equation was compared with modeling based on the commonly used but less general local mean energy approximation. For modeling based on the local time-dependent electron Boltzmann equation, a temporary faster decay in the population of electrons in the high energy tail, and a slower decay in the population of intermediate energy electrons was observed while the electron swarm cooled from an average energy of above 8 eV, without an electric field present. During that period, the electron impact reaction rate coefficients of helium direct ionization and electronic excitation decreased by more than 3 orders of magnitude as compared to the modeling based on the local mean energy approximation. Global modeling of the evolution of plasma species densities in response to an electric field typical of atmospheric pressure pulsed discharges was performed with the two approaches to electron kinetics. Differences in the species densities were observed between the two approaches, with an 100% increase in the maximum density of electrons found with the modeling based on the local mean energy approximation.info:eu-repo/semantics/publishedVersio

    Lung function indices for predicting mortality in COPD

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    Chronic obstructive pulmonary disease (COPD) is characterised by high morbidity and mortality. It remains unknown which aspect of lung function carries the most prognostic information and if simple spirometry is sufficient. Survival was assessed in COPD outpatients whose data had been added prospectively to a clinical audit database from the point of first full lung function testing including spirometry, lung volumes, gas transfer and arterial blood gases. Variables univariately associated with survival were entered into a multivariate Cox proportional hazard model. 604 patients were included (mean±sd age 61.9±9.7 years; forced expiratory volume in 1 s 37±18.1% predicted; 62.9% males); 229 (37.9%) died during a median follow-up of 83 months. Median survival was 91.9 (95% CI 80.8–103) months with survival rates at 3 and 5 years 0.83 and 0.66, respectively. Carbon monoxide transfer factor % pred quartiles (best quartile (>51%): HR 0.33, 95% CI 0.172–0.639; and second quartile (51–37.3%): HR 0.52, 95% CI 0.322–0.825; versus lowest quartile (<27.9%)), age (HR 1.04, 95% CI 1.02–1.06) and arterial oxygen partial pressure (HR 0.85, 95% CI 0.77–0.94) were the only parameters independently associated with mortality. Measurement of gas transfer provides additional prognostic information compared to spirometry in patients under hospital follow-up and could be considered routinely

    Anti-nociceptive, anti-inflammatory and antipyretic effects of the methanolic extract of Bombax buonopozense leaves in rats and mice

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    Methanolic extract of Bombax buonopozense was evaluated for possible anti-nociceptive, antiinflammatory and anti-pyretic activities in mice and rats. Acetic acid-induced abdominal constriction test in mice and formalin test in rats were used to investigate the antinociceptive effect of the extract. Studies were carried out on yeast-induced pyrexia and egg albumin-induced anti-inflammatory activity in rats. The extract produced a significant decrease in acetic acid-induced writhing in mice and inhibition of late phase of the formalin pain test in rats. The methanolic extract of B. buonopozense leaf also produced a potent antipyretic effect and significant inhibition of egg  albumin-induced antiinflammatory activity in rats. The result suggests that B. buonopozense contains biologically active substances with potential values for the treatment of fever, painful and inflammatory conditions.Keywords: Bombax buonopozense; analgesic, inflammation, pyrexia
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