8,269 research outputs found

    CeMnNi4: an impostor half-metal

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    Recent experiments show CeMnNi4_{4} to have a nearly integer magnetic moment and a relatively large transport spin polarization, as probed by Andreev reflection, suggesting that the material is a half metal or close to it. However, the calculations reported here show that it is not a half metal at all, but rather a semimetal of an unusual nature. Phonon properties should also be quite unusual, with rattling low-frequency Mn modes. Nontrivial transport properties, including a large thermolectric figure of merit, ZT,ZT, are predicted in the ferromagnetic state of the well ordered stoichiometric CeMnNi4_{4}Comment: 4 pages, 6 fig

    TIME VARIATION AND ASYMMETRY IN THE WORLD PRICE OF COVARIANCE RISK: THE IMPLICATIONS FOR INTERNATIONAL DIVERSIFICATION

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    The International Capital Asset Pricing Model measures country risk in terms of the conditional covariance of national returns with the world return. Using impulse responses from a multivariate nonlinear model we provide evidence of time variation and asymmetry in the measure of country risk. and the implied benefit to international diversification. The evidence implies that the price of risk and the benefits from diversification may differ in a statistically and economically meaningful fashion across bull and bear markets.Generalised Impulse Responses; Asymmetry; International Capital Asset Pricing Model.

    Non-linear Co-Movements in Output Growth: Evidence from the United States and Australia

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    This paper investigates comovements between the United States and Australia. Our nonlinear model allows the dynamic response to shocks to differ if countries are in recession. Generalised Impulse Response Functions highlight a significant asymmetric response to positive and negative shocks.Current Depth of Recession Models, Generalised Impulse Response Functions, Asymmetries

    Manipulator system man-machine interface evaluation program

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    Application and requirements for remote manipulator systems for future space missions were investigated. A manipulator evaluation program was established to study the effects of various systems parameters on operator performance of tasks necessary for remotely manned missions. The program and laboratory facilities are described. Evaluation criteria and philosophy are discussed

    Test report, earth orbiter teleoperator visual system evaluation program

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    Work carried out to identify human performance requirements for remotely manned system is reported. Specifically, an evaluation was made of the human visual system. Data cover distance estimation 4, solid target alignment 2, motion detection 1, and motion detection 2

    The Asymmetric Effects of Uncertainty on Inflation and Output Growth

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    We study the effects of growth volatility and inflation volatility on average rates of output growth and inflation for post-war U.S. data. Our results suggest that growth uncertainty is associated with higher average growth and lower average inflation. Inflation uncertainty is significantly negatively correlated with both output growth and average inflation. Both inflation and growth display evidence of significant asymmetric response to positive and negative shocks of equal magnitude.growth, inflation, uncertainty, asymmetry, generalised impluse response functions

    A study of payload specialist station monitor size constraints

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    Constraints on the CRT display size for the shuttle orbiter cabin are studied. The viewing requirements placed on these monitors were assumed to involve display of imaged scenes providing visual feedback during payload operations and display of alphanumeric characters. Data on target recognition/resolution, target recognition, and range rate detection by human observers were utilized to determine viewing requirements for imaged scenes. Field-of-view and acuity requirements for a variety of payload operations were obtained along with the necessary detection capability in terms of range-to-target size ratios. The monitor size necessary to meet the acuity requirements was established. An empirical test was conducted to determine required recognition sizes for displayed alphanumeric characters. The results of the test were used to determine the number of characters which could be simultaneously displayed based on the recognition size requirements using the proposed monitor size. A CRT display of 20 x 20 cm is recommended. A portion of the display area is used for displaying imaged scenes and the remaining display area is used for alphanumeric characters pertaining to the displayed scene. The entire display is used for the character alone mode

    Earth orbital teleoperator system man-machine interface evaluation

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    The teleoperator system man-machine interface evaluation develops and implements a program to determine human performance requirements in teleoperator systems

    THE EFFECT OF ODOURS, IRRITANT VAPOURS, AND MENTAL WORK UPON THE BLOOD FLOW

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    The most important of this investigation has been the completion of various improvements in the construction and use of the plethysmograph, by means of which numerous errors attending the use of the instrument have been eliminated. The results of the work show that all olfactory sensations, so far as they produce any effect through the vasomotor system, tend to diminish the volume of the arm, and therefore presumably cause a congestion of the brain. Whenever the stimulation occassions an increase in the volume of the arm, as sometimes happens, it seems to be due to acceleration of the heart rate, which, of course, tends also to increase the supply of blood to the brain. The of odours varies in extent with different individuals, and with the same individual at different times. It was most marked in subjects sensitive to odours. Irritant vapours, such as formic acid, have a marked effect in the same direction—that is, they cause a strong diminution in the volume of the arm. The experiments give no support to the view that pleasant sensations are accompanied by a diminution of the See PDF for Structure blood supply to the brain and unpleasant sensations by the reverse efeect. In all my experiments mental work caused a marked and prolonged diminution in the volume of the arm. This vasomotor effect was sometimes preceded by a transitory increase in the volume of the arm caused by acceleration of heart rate

    Human operator performance of remotely controlled tasks: Teleoperator research conducted at NASA's George C. Marshal Space Flight Center

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    The capabilities within the teleoperator laboratories to perform remote and teleoperated investigations for a wide variety of applications are described. Three major teleoperator issues are addressed: the human operator, the remote control and effecting subsystems, and the human/machine system performance results for specific teleoperated tasks
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