528 research outputs found

    The Term Structure of Interest Rates

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    This paper consolidates and interprets the literature on the term structure, as it stands today. Definitions of rates of return, forward rates and holding returns for all time intervals are treated here in a uniform manner and their interrelations, exact or approximate, delineated. The concept of duration is used throughout to simplify mathematical expressions. Continuous compounding is used where possible, to avoid arbitrary distinctions based on compounding assumptions. Both the theoretical and the empirical literature are treated. The attached tables by J. Huston McCulloch give term structure data for U. S. government securities 1946-1987. The tables give discount bond yields, forward rates and par bond yields as defined in the paper. The data relate to the concepts in the paper more precisely than does any previously published data series.

    History, a projection of the future: A rotary wing perspective

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    The success and failure of past vehicle concepts is reviewed in an attempt to highlight some of the advanced vehicle concepts attempted in the past failed because of a lack of appreciation, by both the sponsors and the developer, for the technical and societal requirements critical to their success. This paper will review the history of some attempts to provide both good hover and forward flight efficiency and will point out some of the technical and societal obstacles encountered. Two examples, that of the tiltrotor and tiltwing vehicles. will be highlighted show the different paths followed by a successful and an unsuccessful concept. The outlook for future VTOL/rotary wing concepts will be evaluated

    The Term Structure of Interest Rates (with U.S. Government Term Structure Data)

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    This paper consolidates and interprets the literature on the term structure, as it stands today. Definitions of rates of return, forward rates and holding returns for all time intervals are treated here in a uniform manner and their interrelations, exact or approximate, delineated. The concept of duration is used throughout to simplify mathematical expressions. Continuous compounding is used where possible, to avoid arbitrary distinctions based on compounding assumptions. Both the theoretical and the empirical literature are treated. The attached tables by J. Huston McCulloch give term structure data for U.S. government securities 1946-1987. The tables give discount bond yields, forward rates and par bond yields as defined in the paper. The data relate to the concepts in the paper more precisely than does any previously published data series

    Data from a Static-Thrust Investigation of Large-Scale General Research VTOL-STOL Model in Ground Effect

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    The model was tested at two different elevations with the wing pivot at 1.008 and 2.425 propeller diameters above the ground. The slipstream of the propellers was deflected by tilting the wing and propellers, by deflections of large-chord trailing-edge flaps, and by combinations of flap deflection and wing tilt. Tests were conducted over a range of propeller disk loadings from 7.41 to 29.70 pounds per square foot. Force data for the complete model and pressure distributions for the wing and flaps behind one propeller were recorded and are presented in tabular form without analysis

    Angiography-negative primary central nervous system vasculitis: a syndrome involving small cerebral vessels

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    Primary central nervous system vasculitis (PCNSV) is a rare and poorly understood syndrome. We describe the clinical findings in 8 patients who appear to have a distinct subset of PCNSV. We identified 101 consecutive patients with PCNSV who were seen between January 1, 1983, and December 31, 2003. The diagnosis was based on conventional angiography in 70 patients and on central nervous system biopsy in 31 patients. Six of the 31 patients also had angiograms showing changes of vasculitis. Thus, 76 patients of the cohort had abnormal angiograms. Eight of the 101 patients had normal angiograms ("angiography-negative") but had brain biopsies that showed vasculitis. We compared the clinical and laboratory findings and outcomes of the 8 patients with angiography-negative PCNSV with those of the 76 patients with PCNSV whose angiograms showed evidence of vasculitis ("angiography-positive"). In comparison with the 76 patients with angiography-positive PCNSV, the 8 patients with angiography-negative PCNSV more commonly had 1) a cognitive disorder (87.5% vs. 43.4%; p =.024); 2) cerebrospinal fluid abnormalities (a protein level >or=700 mg/L or a white blood cell count >or=10 x 10(6)/L) (100% vs. 35.5%; p =.034); and 3) meningeal or parenchymal enhancing lesions on magnetic resonance imaging (75.0% vs. 23.9%; p =.007). Other differences between the 2 groups were observed but were not significantly different. All patients with angiography-negative PCNSV responded to treatment and none died. Angiography-negative PCNSV appears to be a distinct subtype of cerebral vasculitis with small vessel involvement beyond the resolution of conventional angiography and is associated with a favorable outcome

    Higgs-boson production associated with a bottom quark at hadron colliders with SUSY-QCD corrections

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    The Higgs boson production p p (p\bar p) -> b h +X via b g -> b h at the LHC, which may be an important channel for testing the bottom quark Yukawa coupling, is subject to large supersymmetric quantum corrections. In this work the one-loop SUSY-QCD corrections to this process are evaluated and are found to be quite sizable in some parameter space. We also study the behavior of the corrections in the limit of heavy SUSY masses and find the remnant effects of SUSY-QCD. These remnant effects, which are left over in the Higgs sector by the heavy sparticles, are found to be so sizable (for a light CP-odd Higgs and large \tan\beta) that they might be observable in the future LHC experiment. The exploration of such remnant effects is important for probing SUSY, especially in case that the sparticles are too heavy (above TeV) to be directly discovered at the LHC.Comment: Results for the Tevatron adde

    The Surgical Infection Society revised guidelines on the management of intra-abdominal infection

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    Background: Previous evidence-based guidelines on the management of intra-abdominal infection (IAI) were published by the Surgical Infection Society (SIS) in 1992, 2002, and 2010. At the time the most recent guideline was released, the plan was to update the guideline every five years to ensure the timeliness and appropriateness of the recommendations. Methods: Based on the previous guidelines, the task force outlined a number of topics related to the treatment of patients with IAI and then developed key questions on these various topics. All questions were approached using general and specific literature searches, focusing on articles and other information published since 2008. These publications and additional materials published before 2008 were reviewed by the task force as a whole or by individual subgroups as to relevance to individual questions. Recommendations were developed by a process of iterative consensus, with all task force members voting to accept or reject each recommendation. Grading was based on the GRADE (Grades of Recommendation Assessment, Development, and Evaluation) system; the quality of the evidence was graded as high, moderate, or weak, and the strength of the recommendation was graded as strong or weak. Review of the document was performed by members of the SIS who were not on the task force. After responses were made to all critiques, the document was approved as an official guideline of the SIS by the Executive Council. Results: This guideline summarizes the current recommendations developed by the task force on the treatment of patients who have IAI. Evidence-based recommendations have been made regarding risk assessment in individual patients; source control; the timing, selection, and duration of antimicrobial therapy; and suggested approaches to patients who fail initial therapy. Additional recommendations related to the treatment of pediatric patients with IAI have been included. Summary: The current recommendations of the SIS regarding the treatment of patients with IAI are provided in this guideline

    A Student\u27s Guide to giant Viruses Infecting Small Eukaryotes: From Acanthamoeba to Zooxanthellae

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    The discovery of infectious particles that challenge conventional thoughts concerning “what is a virus” has led to the evolution a new field of study in the past decade. Here, we review knowledge and information concerning “giant viruses”, with a focus not only on some of the best studied systems, but also provide an effort to illuminate systems yet to be better resolved. We conclude by demonstrating that there is an abundance of new host–virus systems that fall into this “giant” category, demonstrating that this field of inquiry presents great opportunities for future research
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