847 research outputs found

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    Analysis of iced wings

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    A method for computing ice shapes along the leading edge of a wing and a method for predicting its aerodynamic performance degradation due to icing is described. Ice shapes are computed using an extension of the LEWICE code which was developed for airfoils. The aerodynamic properties of the iced wing are determined with an interactive scheme in which the solutions of the inviscid flow equations are obtained from a panel method and the solutions of the viscous flow equations are obtained from an inverse three-dimensional finite-difference boundary-layer method. A new interaction law is used to couple the inviscid and viscous flow solutions. The application of the LEWICE wing code to the calculation of ice shapes on a MS-317 swept wing shows good agreement with measurements. The interactive boundary-layer method is applied to a tapered ice wing in order to study the effect of icing on the aerodynamic properties of the wing at several angles of attack

    Assessment of economic factors affecting the satellite power system. Volume 2: The systems implications of rectenna siting issues

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    The feasibility was evaluated of finding potential sites for Solar Power Satellite (SPS) receiving antennas (rectennas) in the continental United States, in sufficient numbers to permit the SPS to make a major contribution to U.S. generating facilities, and to give statistical validity to an assessment of the characteristics of such sites and their implications for the design of the SPS system. It is found that the cost-optimum power output of the SPS does not depend on the particular value assigned to the cost per unit area of a rectenna and its site, as long as it is independent of rectenna area. Many characteristics of the sites chosen affect the optimum design of the rectenna itself

    Syntactic or semantic gender agreement in Dutch, German, and German learner Dutch. A speeded grammaticality judgement task

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    Dutch is currently undergoing a ‘resemanticisation’ of its pronominal gender, in which syntactic agreement is replaced with a system in which pronouns are chosen in accordance with the degree of individuation of the antecedent. Current accounts of resemanticisation link the process to the extent to which the three-way nominal gender distinctions are still entrenched. Using experimental data gathered with speeded grammaticality judgements from speakers of both Netherlandic and Belgian varieties of Dutch, of German, and of German learners of Dutch, we unambiguously relate the rise of semantic agreement in Dutch to an increased uncertainty with respect to grammatical gender. In addition, reaction time measurements suggest that an agreement system with a strong propensity towards grammatical agreement allows for faster processing of agreement relations than systems in which semantic agreement plays a larger role.Im Niederländischen findet zurzeit eine ‘Resemantisierung’ des pronominalen Genus statt, durch die syntaktische Kongruenz zunehmend durch ein System ersetzt wird, in dem die Wahl pronominaler Formen vom Grad der Individuierung des Antezedenten abhängt. Es wurde vermutet, dass der Prozess mit dem Grad der Verankerung (entrenchment) des Drei-Genera-Systems zusammenhängt. Anhand von Grammatikalitätsurteilen unter Zeitdruck (speeded grammaticality judgements) mit Sprechern niederländischer und belgischer Varietäten und mit Sprechern des Deutschen durchgeführt, sowie auch mit deutschen Niederländischlernern, demonstrieren wir eindeutig den Zusammenhang zwischen der Zunahme semantischer Kongruenz und einer Unsicherheit in Bezug auf das grammatische Genus. Darüber hinaus sprechen die Analysen der Reaktionszeiten dafür, dass sein stark grammatisch basiertes Genussystem eine schnellere Verarbeitung von Kongruenzbeziehungen erlaubt als ein System, in dem semantische Kongruenz eine größere Rolle spielt

    Does contrast echocardiography induce increases in markers of myocardial necrosis, inflammation and oxidative stress suggesting myocardial injury?

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    BACKGROUND: Contrast echocardiography is a precise tool for the non-invasive assessment of myocardial function and perfusion. Side effects of contrast echocardiography resulting from contrast-agent induced myocardial micro-lesions have been found in animals. The goal of this study is to measure markers of myocardial necrosis, inflammation and oxidative stress in humans to evaluate potential side-effects of contrast echocardiography. METHODS: 20 patients who underwent contrast echocardiography with Optison as the contrast medium were investigated. To evaluate myocardial micro-necrosis, inflammation and oxidative stress, cardiac troponin I (cTnI), tumor necrosis factor-α (TNF-α), interleukin (IL)-6, -8 and thiobarbituric acid reactive substances (TBARS) were measured at baseline and at 2, 4, 8 and 24 hours after contrast echocardiography. RESULTS: At baseline, 50% of the patients had cTnI and TBARS values outside the reference range. TNF-α, IL-6, IL-8 levels were within the reference range. Patients with cTnI above the RR clustered to significantly higher levels of TNF-α and IL-6. After contrast echocardiography, no statistically significant increase of cTnI, cytokines and TBARS was found. However, for nearly 50% of the patients, the intra-individual cTnI kinetics crossed the critical difference (threefold of methodical variation) which indicates a marker increase. This was neither predicted by the baseline levels of the cytokines nor the markers of oxidative stress. CONCLUSION: There are no clinically relevant increases in serum markers for micro-necrosis, inflammation and oxidative stress in humans after contrast echocardiography. Future studies have to address whether cTnI increase in some patients represent a subset with increased risk for side effects after contrast echocardiography

    Early neuromodulation prevents the development of brain and behavioral abnormalities in a rodent model of schizophrenia

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    The notion that schizophrenia is a neurodevelopmental disorder in which neuropathologies evolve gradually over the developmental course indicates a potential therapeutic window during which pathophysiological processes may be modified to halt disease progression or reduce its severity. Here we used a neurodevelopmental maternal immune stimulation (MIS) rat model of schizophrenia to test whether early targeted modulatory intervention would affect schizophrenia’s neurodevelopmental course. We applied deep brain stimulation (DBS) or sham stimulation to the medial prefrontal cortex (mPFC) of adolescent MIS rats and respective controls, and investigated its behavioral, biochemical, brain-structural and -metabolic effects in adulthood. We found that mPFC-DBS successfully prevented the emergence of deficits in sensorimotor gating, attentional selectivity and executive function in adulthood, as well as the enlargement of lateral ventricle volumes and mal-development of dopaminergic and serotonergic transmission. These data suggest that the mPFC may be a valuable target for effective preventive treatments. This may have significant translational value, suggesting that targeting the mPFC before the onset of psychosis via less invasive neuromodulation approaches may be a viable preventive strategy.We thank Renate Winter, Doris Zschaber and Roselies Pickert for excellent technical assistance. This research was conducted under the EraNet Neuron framework (DBS_F20rat) and supported by the BMBF, Germany (B01EW1103, 01EE1403A), Fundación Mapfre, Comunidad de Madrid and the Ministry of Economy and Competitiveness ISCIII-FIS grants (PI14/00860, CPII/00005) co-financed by ERDF (FEDER) Funds from the European Commission, ‘A way of making Europe’, Spain (PI14/00860, CPII/00005, MV1500002), the CSO-MOH, Israel (3-8580) and the Canadian Institutes of Health Research, Canada (CIHR, 110068), and co-financed by the DFG, Germany (WI 2140/1-1/2; WI 2140/2-1).Publicad
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