20,975 research outputs found

    Forward-scatter radiant mapping

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    Forward-scatter systems have been much neglected for the study of meteors and meteor streams. A great deal of this neglect stems from the complicated geometry which has made the interpretation of results difficult in the past. This no longer presents a problem because of the computer power now available. There are practical advantages in using forward-scatter in that low-power transmitters are much easier to handle than the high-power ones used in pulsed back-scatter radars. The data reduction of the CW signals is also significantly simpler. Because the forward-scatter reflection geometry increases the duration of the echoes relative to the back-scatter case, the problem of the underdense ceiling is partially alleviated. We have built a 'short hop' forward-scatter system between Ottawa and London (Ont) for which the transmitter and receiver are separated by about 500 km. With it, we are able to measure unambiguously the directions of arrival of the echoes using a 5-antenna interferometer. Morton and Jones (1982, MN, 198, 737) have shown how the echo direction distribution can be deconvolved to yield the meteor radiant distribution for back-scatter data. We have extended the technique to the forward-scatter case and present some preliminary meteor radiant distribution maps

    Qualitative evaluation of a conformal velocity vector display for use at high angles-of-attack in fighter aircraft

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    A piloted simulation study was conducted to evaluate the utility of a display device designed to illustrate graphically and conformally the approximate location of a fighter aircraft's velocity vector. The display device consisted of two vertical rows of light emitting diodes (LED's) located toward the center of the cockpit instrument panel to each side of the control stick. The light strings provided a logical extension of the head up display (HUD) velocity vector symbol at flight path angles which exceeded the HUD field-of-view. Four test subjects flew a modified F/A-18 model with this display in an air-to-air engagement task against an equally capable opponent. Their responses to a questionnaire indicated that the conformal velocity vector information could not be used during the scenarios investigated due to the inability to visually track a target and view the lights simultaneously

    A farm level assessment of the profitability of Entry Level Scheme participation in the Lincolnshire Wolds

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    The paper builds on the results of previous studies investigating whether farmers profit by participation in the Entry Level Scheme (ELS). Standard payment levels (derived from points) under ELS are fixed at rates that are expected only to compensate farmers for income foregone and costs incurred. There is no profit element as such. There is therefore no reason to expect participation to be profitable. However farm level examination of the income foregone and costs incurred in previous studies based in other parts of England have shown that this can be achieved. The study is based in the Lincolnshire Wolds, an area dominated by arable farming but with topography and associated natural features that offer some variety in the mix of farming and the measures that can qualify for environmental prescriptions under the scheme. The study concluded that farmers were able to profit by ELS participation but that the extent of this varied according to the type of environmental features on the farm and whether arable land was taken out of production. These conclusions have potential implications for scheme design, farmer uptake and additionality in the use of public funds to acquire environmental benefits.Entry Level Scheme, agri-environmental payments, income forgone, partial budgets, profitability., Farm Management, Q58,

    IF YOU BUILD THEM UP, THEY WILL STAY : THE ROLE OF RECOGNITION AND FEEDBACK ON STUDENT RETENTION

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    While such stratagems are certainly well founded, and have achieved varying degrees of success, it may be that a more fundamentally vital area of examination is being largely overlooked, namely the impact of the high school experience

    After NAFTA, Looking South

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    After NAFTA, Looking South

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    Open Markets, Competitive Democracy, and Transparent and Reliable Legal Systems: The Three Legs of Development

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    In the 1990s, reform swept through Latin America. Open markets replaced closed economies. Real democracy replaced one-party rule and rigged elections. For about half of the region\u27s population, economic and political conditions improved—yet the gap between the rich and poor widened. The poor half received little or no tangible benefits from these economic and democratic reforms. This article argues that the most difficult and probably most important reform remains to be accomplished: the reform of the legal and regulatory systems throughout Latin America. Until that happens, dreams of first-world recognition and respectability will elude Latin nations

    Concepts for conformal and body-axis attitude information for spatial awareness presented in a helmet-mounted display

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    A piloted simulation study has been conducted to evaluate two methods of presenting attitude information in a helmet-mounted display (HMD) for spatial awareness in a fighter airplane. One method, the body-axis concept, displayed the information relative to the body axis of the airplane. The quantitative results of this study favored the body-axis concept. Although no statistically significant differences were noted for either the pilots' understanding of roll attitude or target position, the pilots made pitch judgment errors three times more often with the conformal display. The subjective results showed the body-axis display did not cause attitude confusion, a prior concern with this display. In the posttest comments, the pilots overwhelmingly selected the body-axis display as the display of choice

    Managerial Valuation of Applicant Credentials and Personal Traits in Hiring Decisions

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    We study how managers value applicant credentials and personal traits in hiring decisions. Using the ordered probit model, we confirm previous results – managers rank applicant traits higher than credentials. However, we also uncover patterns not previously observed – managerial valuations of some of these characteristics are dependent on managers' perception of the overall state of the economy, on firm and immediate workplace characteristics, and on managers' personal characteristics. Manager valuations of credentials vary with a large number of factors; this is not so for applicant personal traits. This is not surprising as most managers view the five traits considered "as extremely important."personality, credentials, hiring practices, ordered probit
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