20,319 research outputs found

    Analytic evaluation of display requirements for approach to landing

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    A pilot-vehicle-display model is used to study information and display requirements and the effects on system performance and reliability of pilot-induced randomness, wind gusts, configurational changes, etc. A brief description of a control theoretic systems model is given and its use and validity are demonstrated by applying it in a piloted approach to landing situation. The analysis procedure assumes that the vehicle dynamics are represented by linearized equations of motion

    Manned Vehicle Systems Analysis by Means of Modern Control Theory

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    Optimal control theory and systems analysis of man machine systems and operator performance prediction model for compensatory tracking tasks are discussed

    Closed loop models for analyzing the effects of simulator characteristics

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    The optimal control model of the human operator is used to develop closed loop models for analyzing the effects of (digital) simulator characteristics on predicted performance and/or workload. Two approaches are considered: the first utilizes a continuous approximation to the discrete simulation in conjunction with the standard optimal control model; the second involves a more exact discrete description of the simulator in a closed loop multirate simulation in which the optimal control model simulates the pilot. Both models predict that simulator characteristics can have significant effects on performance and workload

    A study of the Markov game approach to tactical maneuvering problems

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    Application of Markov game approach to planar air combat problem

    Sensitivity of a high‐elevation rocky mountain watershed to altered climate and CO2

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    We explored the hydrologic and ecological responses of a headwater mountain catchment, Loch Vale watershed, to climate change and doubling of atmospheric CO2 scenarios using the Regional Hydro‐Ecological Simulation System (RHESSys). A slight (2°C) cooling, comparable to conditions observed over the past 40 years, led to greater snowpack and slightly less runoff, evaporation, transpiration, and plant productivity. An increase of 2°C yielded the opposite response, but model output for an increase of 4°C showed dramatic changes in timing of hydrologic responses. The snowpack was reduced by 50%, and runoff and soil water increased and occurred 4–5 weeks earlier with 4°C warming. Alpine tundra photosynthetic rates responded more to warmer and wetter conditions than subalpine forest, but subalpine forest showed a greater response to doubling of atmospheric CO2 than tundra. Even though water use efficiency increased with the double CO2 scenario, this had little effect on basin‐wide runoff because the catchment is largely unvegetated. Changes in winter and spring climate conditions were more important to hydrologic and vegetation dynamics than changes that occurred during summer

    Glutathione treatment protects the rat liver against injury after warm ischemia and Kupffer cell activation

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    Background/Aim: The generation of reactive oxygen species by activated Kupffer cells (KC) may contribute to reperfusion injury of the liver during liver transplantation or resection. The aim of our present studies was to investigate (1) prevention of hepatic reperfusion injury after warm ischemia by administration of the antioxidant glutathione (GSH) and (2) whether GSH confers protection through influences on KC toxicity. Methods: Isolated perfused rat livers were subjected to 1 h of warm ischemia followed by 90 min of reperfusion without (n = 5) or with GSH or catalase (n = 4-5 each). Selective KC activation by zymosan (150 mug/ml) in continuously perfused rat livers was used to investigate KC-related liver injury. Results: Postischemic infusion of 0.1, 0.5, 1.0 and 2.0 mM GSH, but not 0.05 mM GSH prevented reperfusion injury after warm ischemia as indicated by a marked reduction of sinusoidal LDH efflux by up to 83 +/- 13% (mean +/- SD; p < 0.05) and a concomitant significant improvement of postischemic bile flow by 58 +/- 27% (p < 0.05). A similar protection was conveyed by KC blockade with gadolinium chloride indicating prevention of KC-related reperfusion injury by postischemic GSH treatment. Postischemic treatment with catalase (150 U/ml) resulted in a reduction of LDH efflux by 40 +/- 9% (p < 0.05). Accordingly, catalase as well as GSH (0.1-2.0 mM) nearly completely prevented the increase in LDH efflux following selective :KC activation by zymosan in continously perfused rat livers. Conclusion: Postischemic administration of GSH protects the liver against reperfusion injury after warm ischemia. Detoxification of KC-derived hydrogen peroxide seem to be an important feature of the protective mechanisms. Copyright (C) 2002 S. Karger AG, Basel

    Do adults with high functioning autism or Asperger Syndrome differ in empathy and emotion recognition?

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    The present study examined whether adults with high functioning autism (HFA) showed greater difficulties in (i) their self-reported ability to empathise with others and/or (ii) their ability to read mental states in others’ eyes than adults with Asperger syndrome (AS). The Empathy Quotient (EQ) and ‘Reading the Mind in the Eyes’ Test (Eyes Test) were compared in 43 adults with AS and 43 adults with HFA. No significant difference was observed on EQ score between groups, while adults with AS performed significantly better on the Eyes Test than those with HFA. This suggests that adults with HFA may need more support, particularly in mentalizing and complex emotion recognition, and raises questions about the existence of subgroups within autism spectrum conditions
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