36 research outputs found

    Susceptibility testing of Haemophilus influenzae - An international collaborative study in quality assessment

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    In order to compare the prevalence of antibiotic resistance in different geographical areas, it is necessary to ensure that agreement is achieved between laboratories on the assignment of strains to 'susceptible' and 'resistant' categories. An international quality assessment study, involving 15 laboratories in eight countries, was performed to investigate the standard of performance of the susceptibility testing of Haemophilus influenzae. One hundred and fifty strains of H. influenzae were distributed from the London Hospital Medical College (LHMC) to all laboratories who were asked to test the susceptibility of the strains to ampicillin, chloramphenicol, tetracycline, trimethoprim, cephalosporins and ciprofloxacin. Laboratories were also asked to provide the details of methodology to test the susceptibility. Significant discrepancy between the LHMC and the participating laboratories appeared in the detection of resistance to ampicillin (especially β-lactamase-negative strains resistant to ampicillin) as well as the assignment of susceptibility and resistance to chloramphenicol, tetracycline and trimethoprim. Often these reflected the use of inappropriate breakpoints which led to erroneous assignment of susceptibility. Other variations including disc content, medium and supplement, inoculum as well as failure to measure zone sizes properly also led to some repeating anomalies

    Multipole analysis of redshift-space distortions around cosmic voids

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    We perform a comprehensive redshift-space distortion analysis based on cosmic voids in the large-scale distribution of galaxies observed with the Sloan Digital Sky Survey. To this end, we measure multipoles of the void-galaxy cross-correlation function and compare them with standard model predictions in cosmology. Merely considering linear-order theory allows us to accurately describe the data on the entire available range of scales and to probe void-centric distances down to about 2h1Mpc2h^{-1}{\rm Mpc}. Common systematics, such as the Fingers-of-God effect, scale-dependent galaxy bias, and nonlinear clustering do not seem to play a significant role in our analysis. We constrain the growth rate of structure via the redshift-space distortion parameter β\beta at two median redshifts, β(zˉ=0.32)=0.5990.124+0.134\beta(\bar{z}=0.32)=0.599^{+0.134}_{-0.124} and β(zˉ=0.54)=0.4570.054+0.056\beta(\bar{z}=0.54)=0.457^{+0.056}_{-0.054}, with a precision that is competitive with state-of-the-art galaxy-clustering results. While the high-redshift constraint perfectly agrees with model expectations, we observe a mild 2σ2\sigma deviation at zˉ=0.32\bar{z}=0.32, which increases to 3σ3\sigma when the data is restricted to the lowest available redshift range of 0.15<z<0.330.15<z<0.33.Comment: 20 pages, 11 figures. Minor fixes, conclusions unchanged. Reflects published versio

    Early defoliation (hand vs mechanical) for improved crop control and grape composition in Sangiovese (Vitis vinifera L.)

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    It is well known that the number of pre-bloom source leaves is a primary determinant of subsequent fruit set. Accordingly, we tested whether pre- and post-bloom manual and mechanical defoliation is effective in limiting yield on a high cropping cultivar like Sangiovese in a three-year field study. The first six basal leaves and any laterals were removed by hand and the same area was subjected to mechanical defoliation by a suction unit, the latter removing just less than half the area removed manually. Both treatments significantly reduced fruit-set, yield per shoot, bunch weight, berries per bunch and bunch compactness. The effects of hand removal were more stable from year to year and had the biggest impact regardless of treatment date, respectively reducing fruit set and yield per shoot by 34% and 42%. Leaf-to-fruit ratios were unaffected by defoliation since source loss was fully offset by yield decline. Both treatments improved soluble solids and total anthocyanins on a fresh-weight basis as compared to non-defoliated control. Improved quality correlated to compensatory post-treatment photosynthesis and was likely linked to increased bunch sink strength and light exposure. While the results from the hand treatment reinforce the physiological basis of the technique’s effectiveness and its relative insensitivity to year-to-year variability, the positive outcome of the mechanical approach has the potential to regulate yield in a timely and cost-effective fashion while improving quality through enhanced berry composition and looser, less rot-susceptible bunches

    SDSS-III : massive spectroscopic surveys of the distant universe, the Milk Way, and extra-solar planetary systems

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    Building on the legacy of the Sloan Digital Sky Survey (SDSS-I and II), SDSS-III is a program of four spectroscopic surveys on three scientific themes: dark energy and cosmological parameters, the history and structure of the Milky Way, and the population of giant planets around other stars. In keeping with SDSS tradition, SDSS-III will provide regular public releases of all its data, beginning with SDSS Data Release 8 (DR8), which was made public in 2011 January and includes SDSS-I and SDSS-II images and spectra reprocessed with the latest pipelines and calibrations produced for the SDSS-III investigations. This paper presents an overview of the four surveys that comprise SDSS-III. The Baryon Oscillation Spectroscopic Survey will measure redshifts of 1.5 million massive galaxies and Lyα forest spectra of 150,000 quasars, using the baryon acoustic oscillation feature of large-scale structure to obtain percent-level determinations of the distance scale and Hubble expansion rate at z < 0.7 and at z ≈ 2.5. SEGUE- 2, an already completed SDSS-III survey that is the continuation of the SDSS-II Sloan Extension for Galactic Understanding and Exploration (SEGUE), measured medium-resolution (R = λ/Δλ ≈ 1800) optical spectra of 118,000 stars in a variety of target categories, probing chemical evolution, stellar kinematics and substructure, and the mass profile of the dark matter halo from the solar neighborhood to distances of 100 kpc. APOGEE, the Apache Point Observatory Galactic Evolution Experiment, will obtain high-resolution (R ≈ 30,000), high signal-to-noise ratio (S/N 100 per resolution element), H-band (1.51μm < λ < 1.70μm) spectra of 105 evolved, late-type stars, measuring separate abundances for ∼15 elements per star and creating the first high-precision spectroscopic survey of all Galactic stellar populations (bulge, bar, disks, halo) with a uniform set of stellar tracers and spectral diagnostics. The Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS) will monitor radial velocities of more than 8000 FGK stars with the sensitivity and cadence (10–40ms−1, ∼24 visits per star) needed to detect giant planets with periods up to two years, providing an unprecedented data set for understanding the formation and dynamical evolution of giant planet systems. As of 2011 January, SDSS-III has obtained spectra of more than 240,000 galaxies, 29,000 z 2.2 quasars, and 140,000 stars, including 74,000 velocity measurements of 2580 stars for MARVELS
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