52,160 research outputs found

    The remote sensing of aquatic macrophytes Part 1: Color-infrared aerial photography as a tool for identification and mapping of littoral vegetation. Part 2: Aerial photography as a quantitative tool for the investigation of aquatic ecosystems

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    Research was initiated to use aerial photography as an investigative tool in studies that are part of an intensive aquatic ecosystem research effort at Lake Wingra, Madison, Wisconsin. It is anticipated that photographic techniques would supply information about the growth and distribution of littoral macrophytes with efficiency and accuracy greater than conventional methods

    A procedure for furnace brazing butt joints in tungsten-uranium dioxide cermet cylinders at 3000 deg C

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    Furnace brazing butt joints in tungsten-uranium dioxide cermet cylinders at 3000 deg

    Measurement of the Transverse Single Spin Asymmetry of pp + pp^\uparrow \rightarrow η\eta + XX at s\sqrt{s} = 200 GeV

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    The measurement of transverse single spin asymmetries (ANA_N) provides insight into the structure of the nucleon. Several mechanisms have been proposed that attempt to explain ANA_N based on QCD, and additional measurements of ANA_N for different processes further constrain these models. Using the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC), we study transversely polarized p+p collisions. Results from PHENIX and other experiments show significant asymmetries in the forward region, which could be due to contributions from both the Sivers and the Collins effects. Studying the species as well as the kinematic dependencies of these transverse single spin asymmetries will help to disentangle the origin of the observed asymmetries. Therefore, measurements of ANA_N with inclusive η\eta mesons at forward rapidities are an important tool for the understanding of these asymmetries. In 2008, the PHENIX experiment collected 5.2 pb1^{-1} integrated luminosity in p+pp^\uparrow+p collisions at s\sqrt{s} = 200 GeV. The status of the asymmetry analysis of η\eta mesons at forward rapidity will be shown.Comment: 4 pages, 3 figure

    Experimental data on the single spin asymmetry and their interpretations by the chromo-magnetic string model

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    An attempt is made to interpret the various existing experimental data on the single spin asymmetries in inclusive pion production by the polarized proton and antiproton beams. As the basis of analysis the chromo-magnetic string model is used. A whole measured kinematic region is covered. The successes and fails of such approach are outlined. The possible improvements of model are discussed.Comment: 17 pages, 3 figure

    Characterization of low thermal conductivity PAN-based carbon fibers

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    The microstructure and surface chemistry of eight low thermal conductivity (LTC) PAN-based carbon fibers were determined and compared with PAN-based fibers heat treated to higher temperatures. Based on wide-angle x ray diffraction, the LTC PAN fibers all appear to have a similar turbostratic structure with large 002 d-spacings, small crystallite sizes, and moderate preferred orientation. Limited small-angle x ray scattering (SAXS) results indicate that, with the exception of LTC fibers made by BASF, the LTC fibers do not have well developed pores. Transmission electron microscopy shows that the texture of the two LTC PAN-based fibers studied (Amoco T350/23X and /25X) consists of multiple sets of parallel, wavy, bent layers that interweave with each other forming a complex three dimensional network oriented randomly around the fiber axis. X ray photoelectron spectroscopy (XPS) analysis finds correlations between heat treated temperatures and the surface composition chemistry of the carbon fiber samples

    Transverse Momentum Correlations in Relativistic Nuclear Collisions

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    From the correlation structure of transverse momentum ptp_t in relativistic nuclear collisions we observe for the first time temperature/velocity structure resulting from low-Q2Q^2 partons. Our novel analysis technique does not invoke an {\em a priori} jet hypothesis. ptp_t autocorrelations derived from the scale dependence of fluctuations reveal a complex parton dissipation process in RHIC heavy ion collisions. We also observe structure which may result from collective bulk-medium recoil in response to parton stopping.Comment: 10 pages, 10 figures, proceedings, MIT workshop on fluctuations and correlations in relativistic nuclear collision

    Systematic study of the jet fragmentation function for inclusive jet-production in p+p collisions at sqrt{s}=200 GeV in STAR

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    Jet fragmentation functions measured in e^+e^- and p+\bar{p} experiments are well-described on an inclusive hadron level by QCD-based calculations. Fragmentation is expected to be modified by the presence of a strongly interacting medium, but full theoretical description of this modification must still be developed. It has recently been suggested that particle-identified fragmentation functions may provide additional insight into the processes underlying jet quenching. To assess the applicability of QCD-based fragmentation calculations to RHIC data, and to provide a baseline with which to compare fragmentation function measurements in heavy ion collisions, we present the first measurements of charged hadron and particle-identified fragmentation functions of jets reconstructed via a midpoint-cone algorithm from p+p collisions at 200 GeV in STAR. We study the dependence on jet cone-size and jet-energy, and compare the results to PYTHIA simulations based on the Modified Leading Log Approximation (MLLA).Comment: 6 pages, 5 figures, proceedings of Hard Probes 2008 conferenc
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