637 research outputs found

    Reflections on 30 Years of AIDS

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    TOC summary: Although the end of the epidemic is not yet in sight, the remarkable response has improved health around the world

    Development of arcjet and ion propulsion for spacecraft stationkeeping

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    Near term flight applications of arc jet and ion thruster satellite station-keeping systems as well as development activities in Europe, Japan, and the United States are reviewed. At least two arc jet and three ion propulsion flights are scheduled during the 1992-1995 period. Ground demonstration technology programs are focusing on the development of kW-class hydrazine and ammonia arc jets and xenon ion thrusters. Recent work at NASA LeRC on electric thruster and system integration technologies relating to satellite station keeping and repositioning will also be summarized

    Pleistocene and Holocene Carbonate Environments on San Salvador Island, Bahamas: A Field Trip Guide

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    Although isolated and small in size, San Salvador Island is in many ways a unique place - an all carbonates setting on a small, tectonically stable platform, surrounded by deep oceanic waters, and an historical footnote as the widely accepted first landing site of Christopher Columbus in the New World in 1492. Columbus\u27 stay here was brief, and the major events of subsequent history largely have passed San Salvador by. This is not a tourist island; the natural beauty, floras, and faunas of the Bahamas are well preserved here. The overview theme of this series of field excursions on San Salvador will be interpretation of paleodepositional environments for the well-exposed Pleistocene and Holocene carbonate rocks that cap the island and recognition of modem analogues from the varied carbonate environments found on the island and its surrounding shelf. Questions of sea level history, diagenetic change, and the surficial processes operating on carbonate island terranes also will be considered. Our trip will begin with a low-attitude overflight to view features of the main Bahama platform enroute to San Salvador, which lies just beyond the eastern edge of the platform. The field trip leaders all have been working on San Salvador and elsewhere in the Bahamas for the past decade. We have experienced the good and the bad - a pleasant tropical climate, warm and alive marine waters, a generally unspoiled setting, and the friendly Bahamian people, along with sometimes fierce no-see-um attacks, sun-burnt skin, and unexpected soakings from tropical storms. Throughout, the experiences have been rewarding and the challenges of geologic interpretation great. We look forward to sharing some of our findings and experiences with you. Welcome to the Bahamas and San Salvador Island! See other Smith authored Field Trip Guides of Gerace Research Centre

    Media Systems and the Political Information Environment: A Cross-National Comparison

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    To express attitudes and act according to their self-interest, citizens need relevant, up-to-date information about current affairs. But has the increased commercialization in the media market increased or decreased the flow of political information? Hallin and Mancini stress that the existing empirical evidence is fragmented and that this question therefore has been difficult to answer. In this article the authors present new data that allow them to systematically examine how the flow of political information on TV occurs across six Western countries during a thirty-year period. The authors find that the flow of political information through TV varies according to the degree of commercialization. The flow of news and current affairs is lowest in the most commercially oriented television system and among the commercial TV channels. There is however important cross-national variation even within similar media systems. The authorsā€™ data do not suggest a convergence toward the liberal system when it comes to the political information environment on TV. Rather, what strikes them is how strongly resistant some European countries have been to subordinating the needs of democracy to profit making

    The N250 Brain Potential to Personally Familiar and Newly Learned Faces and Objects

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    Studies employing event-related potentials have shown that when participants are monitoring for a novel target face, the presentation of their own face elicits an enhanced negative brain potential in posterior channels approximately 250ā€‰ms after stimulus onset. Here, we investigate whether the own face N250 effect generalizes to other highly familiar objects, specifically, images of the participantā€™s own dog and own car. In our experiments, participants were asked to monitor for a pre-experimentally unfamiliar target face (Joe), a target dog (Experiment 1: Joeā€™s Dog) or a target car (Experiment 2: Joeā€™s Car). The target face and object stimuli were presented with non-target foils that included novel face and object stimuli, the participantā€™s own face, their own dog (Experiment 1), and their own car (Experiment 2). The consistent findings across the two experiments were the following: (1) the N250 potential differentiated the target faces and objects from the non-target face and object foils and (2) despite being non-targets, the own face and own objects produced an N250 response that was equal in magnitude to the target faces and objects by the end of the experiment. Thus, as indicated by its response to personally familiar and recently familiarized faces and objects, the N250 component is a sensitive index of individuated representations in visual memory

    A response to ā€œLikelihood ratio as weight of evidence: a closer lookā€ by Lund and Iyer

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    Recently, Lund and Iyer (L&I) raised an argument regarding the use of likelihood ratios in court. In our view, their argument is based on a lack of understanding of the paradigm. L&I argue that the decision maker should not accept the expertā€™s likelihood ratio without further consideration. This is agreed by all parties. In normal practice, there is often considerable and proper exploration in court of the basis for any probabilistic statement. We conclude that L&I argue against a practice that does not exist and which no one advocates. Further we conclude that the most informative summary of evidential weight is the likelihood ratio. We state that this is the summary that should be presented to a court in every scientific assessment of evidential weight with supporting information about how it was constructed and on what it was based
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