52,918 research outputs found

    Simulation study of gust alleviation in a tilt rotor aircraft, volume 1

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    The response to vertical turbulence in cruise of the HTR XV-15 design is studied using simulation techniques. This design is a modified version of the XV-15 with a hingeless fiberglass soft-in-plane rotor system. The parameters of a gust alleviation system are determined and the performance of the system is evaluated over a range of cruise velocities and altitudes

    Measurements of antenna impedance in the ionosphere. II. Observing frequency greater than the electron gyro frequency

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    Short dipole antenna impedance measurements in ionosphere at observing frequency above electron gyrofrequenc

    Low Intensity Decameter Emissions from Jupiter

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    Low intensity decameter emissions from Jupite

    Central Atlantic regional ecological test site: A prototype regional environmental information system

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    There are no author-identified significant results in this report

    The Unusual Substrate Specificity of a Virulence Associated Serine Hydrolase from the Highly Toxic Bacterium, \u3cem\u3eFrancisella tularensis\u3c/em\u3e

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    Francisella tularensis is the causative agent of the highly, infectious disease, tularemia. Amongst the genes identified as essential to the virulence of F. tularensis was the proposed serine hydrolase FTT0941c. Herein, we purified FTT0941c to homogeneity and then characterized the folded stability, enzymatic activity, and substrate specificity of FTT0941c. Based on phylogenetic analysis, FTT0941c was classified within a divergent Francisella subbranch of the bacterial hormone sensitive lipase (HSL) superfamily, but with the conserved sequence motifs of a bacterial serine hydrolase. FTT0941c showed broad hydrolase activity against diverse libraries of ester substrates, including significant hydrolytic activity across alkyl ester substrates from 2 to 8 carbons in length. Among a diverse library of fluorogenic substrates, FTT0941c preferred α-cyclohexyl ester substrates, matching with the substrate specificity of structural homologues and the broad open architecture of its modeled binding pocket. By substitutional analysis, FTT0941c was confirmed to have a classic catalytic triad of Ser115, His278, and Asp248 and to remain thermally stable even after substitution. Its overall substrate specificity profile, divergent phylogenetic homology, and preliminary pathway analysis suggested potential biological functions for FTT0941c in diverse metabolic degradation pathways in F. tularensis

    CARETS: A prototype regional environmental information system. Volume 12: User evaluation of experimental land use maps and related products from the central Atlantic test site

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    The author has identified the following significant results. Recommendations resulting from the CARETS evaluation reflect the need to establish a flexible and reliable system for providing more detailed raw and processed land resource information as well as the need to improve the methods of making information available to users
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