8,992 research outputs found

    Study of the true performance limits of the Astrometric Multiplexing Area Scanner (AMAS)

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    The Astrometric Multiplexing Area Scanner (AMAS) is an instrument designed to perform photoelectric long focus astrometry of small fields. Modulation of a telescope focal plane with a rotating Ronchi ruling produces a frequency modulated signal from which relative positions and magnitudes can be extracted. Evaluation instrumental precision, accuracy and resolution characteristics with respect to a variety of instrumental and cosmical parameters indicates 1.5 micron precision and accuracy for single stars under specific conditions. This value decreases for increased number of field stars, particularly for fainter stars

    The effects of the exhaust plume on the lightning triggering conditions for launch vehicles

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    Apollo 12 and Atlas Centaur 67 are two launch vehicles that have experienced triggered lightning strikes. Serious consequences resulted from the events; in the case of Atlas Centaur 67, the vehicle and the payload were lost. These events indicate that it is necessary to develop launch rules which would prevent such occurrences. In order to develop valid lightning related rules, it is necessary to understand the effects of the plume. Some have assumed that the plume can be treated as a perfect conductor, and have computed electric field enhancement factors on that basis. The authors have looked at the plume, and believe that these models are not correct, because they ignore the fluid motion of the conducting plates. The authors developed a model which includes this flow character. In this model, the external field is excluded from the plume as it would be for any good conductor, but, in addition, the charge must distribute so that the charge density is zero at some location in the exhaust. When this condition is included in the calculation of triggering enhancement factors, they can be two to three times larger than calculated by other methods which include a conductive plume but don't include the correct boundary conditions. Here, the authors review the relevant features of rocket exhausts for the triggered lightning problem, present an approach for including flowing conductive gases, and present preliminary calculations to demonstrate the effect that the plume has on enhancement factors

    Do Bid-Ask Spreads Or Bid and Ask Depths Convey New Information First?

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    This paper investigates the order in which new information is first reflected in the market – through changes in spreads or through updated depths. We develop an error correction model of spreads and depths and estimate Gonzalo-Granger common factor components using two years of tick-by-tick quote data on all stocks in the Dow Jones Industrial Average. We show that indeed depths rather than spreads are first to impound new information that leads to new quote trends. Specifically, (bid and ask) depths convey information first in virtually every stock in both years, while spreads almost never convey information in 1998, and do so in only 8 out of 30 cases in 1995. Even in those 8 cases, the percentage of new information revealed by spreads ranges from 50 – 59% with the depths accounting for the rest. Our results have important implications for academic research on asymmetric information trading, for security market design, and for public policy.VECM, spreads, depths, information,

    Magnetic resonance imaging of myocardial strain after acute ST-segment-elevation myocardial infarction: a systematic review

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    The purpose of this systematic review is to provide a clinically relevant, disease-based perspective on myocardial strain imaging in patients with acute myocardial infarction or stable ischemic heart disease. Cardiac magnetic resonance imaging uniquely integrates myocardial function with pathology. Therefore, this review focuses on strain imaging with cardiac magnetic resonance. We have specifically considered the relationships between left ventricular (LV) strain, infarct pathologies, and their associations with prognosis. A comprehensive literature review was conducted in accordance with the PRISMA guidelines. Publications were identified that (1) described the relationship between strain and infarct pathologies, (2) assessed the relationship between strain and subsequent LV outcomes, and (3) assessed the relationship between strain and health outcomes. In patients with acute myocardial infarction, circumferential strain predicts the recovery of LV systolic function in the longer term. The prognostic value of longitudinal strain is less certain. Strain differentiates between infarcted versus noninfarcted myocardium, even in patients with stable ischemic heart disease with preserved LV ejection fraction. Strain recovery is impaired in infarcted segments with intramyocardial hemorrhage or microvascular obstruction. There are practical limitations to measuring strain with cardiac magnetic resonance in the acute setting, and knowledge gaps, including the lack of data showing incremental value in clinical practice. Critically, studies of cardiac magnetic resonance strain imaging in patients with ischemic heart disease have been limited by sample size and design. Strain imaging has potential as a tool to assess for early or subclinical changes in LV function, and strain is now being included as a surrogate measure of outcome in therapeutic trials

    Rural Competitiveness: Results of the 1996 Rural Manufacturing Survey

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    Establishments in metropolitan and nonmetropolitan locations are surprisingly similar in their adoption of new technologies, worker skill requirements, use of government programs and technical assistance, exports, and sources of financing, according to the results of a nationwide survey of 3,909 manufacturing businesses. The most widespread concern of both metro and nonmetro businesses appears to be with quality of labor. Survey respondents report rapidly increasing skill requirements, and many report problems finding qualified workers. Quality of local labor is the most frequently cited problem associated with nonmetro business locations. Access to credit, transportation, and telecommunications infrastructure is a problem of secondary importance for both metro and nonmetro respondents. Rural communities face a considerable challenge in supplying workers with needed skills. The fastest-growing skill requirements -- computer, interpersonal/teamwork, and problem-solving skills -- are not central to traditional academic instruction.rural manufacturing, sample survey, worker skills, manufacturing location, credit availability, technology adoption, Community/Rural/Urban Development,

    Unauthorized Legal Practice Prosecutions and Independent Paralegals in Ontario and the United States

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    The issue of unauthorized legal practice involves questions of professionalism and market protection. The legal profession, like other professions, is seen a being particularly successful at excluding others from its area of jurisdiction. Disputes over jurisdiction occur at the edge of this jurisdiction, specifically when certain condition arise. The e conditions are characterized by the indetermination/ technicality (I/T) ratio , where I represents the ideological underpinning of the profession and T represents the technical knowledge. If either the knowledge base or the ideological underpinning deteriorates, the occupation will lose control over its spheres of activity....For an occupation or a profession to feel secure, it must maintain a firm knowledge base and imbue its novices with the necessary ideology

    The Foreign Policies of the Powers

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    Observations on winter injury.

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    Publication authorized September 1, 1922.Digitized 2007 AES.I. Early and late winter injury / F.C. Bradford -- II. An aftermath of winter injury / H.A. Cardinell.Includes bibliographical references ([pt. I], page 16)

    Access to Justice for a New Century: The Way Forward

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    This book is a timely addition to the literature on access to justice. The book\u27s essays address all aspects of the topic, including differing views on the meaning of access to justice; ways to improve access to legal services; litigation and its role in achieving social justice; and the roles of lawyers, citizens, and legal insitutions. Access to Justice for a New Century is based on papers given at an international symposium presented by the Law Society of Upper Canada, sponsored by the Law Foundation of Ontario.https://digitalcommons.osgoode.yorku.ca/faculty_books/1095/thumbnail.jp
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