6,759 research outputs found

    Effect of Feeding Lactobacillus to Pigs Infected with Salmonella typhimurium

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    Pigs were fed 24-hour cultures of Lactobacillus spp. daily for 34 days. On the 8th day of Lactobacillus spp feeding, animals were inoculated with 108 colony-forming units (CFU) of Salmonella typhimurium. Based on these data, feeding Lactobacillus spp. cultures to pigs infected with S. typhimurium reduced the number of animals that were culture-positive for S. typhimurium by fecal and tonsil samples. Further, feeding Lactobacillus spp. cultures reduced the duration of S. typhimurium shedding from tonsil and fecal samples

    Ytterbium-doped tantalum pentoxide waveguide lasers

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    We have demonstrated a Yb:Ta2O5 waveguide laser fabricated by RF magnetron sputtering on oxidised silicon. The waveguide laser was end-pumped with a laser diode at 977 nm and lasing was observed between 1015 and 1020 nm. The launched pump power threshold and slope efficiency were measured to be ~25 mW and 1.78 %, respectively

    WFPC2 LRF Imaging of Emission Line Nebulae in 3CR Radio Galaxies

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    We present HST/WFPC2 Linear Ramp Filter images of high surface brightness emission lines (either [OII], [OIII], or H-alpha+[NII]) in 80 3CR radio sources. We overlay the emission line images on high resolution VLA radio images (eight of which are new reductions of archival data) in order to examine the spatial relationship between the optical and radio emission. We confirm that the radio and optical emission line structures are consistent with weak alignment at low redshift (z < 0.6) except in the Compact Steep Spectrum (CSS) radio galaxies where both the radio source and the emission line nebulae are on galactic scales and strong alignment is seen at all redshifts. There are weak trends for the aligned emission line nebulae to be more luminous, and for the emission line nebula size to increase with redshift and/or radio power. The combination of these results suggests that there is a limited but real capacity for the radio source to influence the properties of the emission line nebulae at these low redshifts (z < 0.6). Our results are consistent with previous suggestions that both mechanical and radiant energy are responsible for generating alignment between the radio source and emission line gas.Comment: 80 pages, 54 figures. Accepted for publication in ApJ

    Untangling the Conceptual Isssues Raised in Reydon and Scholz’s Critique of Organizational Ecology and Darwinian Populations

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    Reydon and Scholz raise doubts about the Darwinian status of organizational ecology by arguing that Darwinian principles are not applicable to organizational populations. Although their critique of organizational ecology’s typological essentialism is correct, they go on to reject the Darwinian status of organizational populations. This paper claims that the distinction between replicators and interactors, raised in modern philosophy of biology but not discussed by Reydon and Scholz, points the way forward for organizational ecologists. It is possible to conceptualise evolving Darwinian populations providing the inheritance mechanism is appropriately specified. By this approach, adaptation and selection are no longer dichotomised, and the evolutionary significance of knowledge transmission is highlightedPeer reviewe

    Vafa-Witten Estimates for Compact Symmetric Spaces

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    We give an optimal upper bound for the first eigenvalue of the untwisted Dirac operator on a compact symmetric space G/H with rk G-rk H\le 1 with respect to arbitrary Riemannian metrics. We also prove a rigidity statement.Comment: LaTeX, 11 pages. V2: Rigidity statement added, minor changes. To appea

    Are all my volunteers here to help out? Clustering events volunteers by their motivations

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    Posed as a question that an event organizer might contemplate in terms of how best to attract and retain event volunteers, this study adds to the event volunteering literature by cluster analysing volunteers sampled at four sports events using items from the Special Event Volunteer Motivation Scale (SEVMS). The 28 items were first subjected to Exploratory Factor Analysis resulting in four factors (Solidary, Purposive, External Traditions/Commitments, and Spare Time), followed by a two-step clustering procedure and a series of post hoc tests to describe and validate the clusters. As a result of this procedure, three distinct clusters were formed: the Altruists, Socials, and Indifferents. The Altruists and Socials were primarily driven by two distinct internal factors, which respectively represented the Purposive and Solidary factors. The Indifferents appeared to be pushed into volunteering by external forces, rather than intrinsic motivations. Validation revealed that the Indifferents were significantly less satisfied with their volunteer experience than the other two clusters and were also less likely to volunteer in the future. Across the four events sampled, there were distinct patterns of cluster representation, with one event in particular substantially overrepresented by the more negatively inclined Indifferents. The management and research implications of these findings are discussed

    X-ray Properties of the GigaHertz-Peaked and Compact Steep Spectrum Sources

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    We present {\it Chandra} X-ray Observatory observations of Giga-Hertz Peaked Spectrum (GPS) and Compact Steep Spectrum (CSS) radio sources. The {\it Chandra} sample contains 13 quasars and 3 galaxies with measured 2-10 keV X-ray luminosity within 1042104610^{42} - 10^{46} erg s1^{-1}. We detect all of the sources, five of which are observed in X-ray for the first time. We study the X-ray spectral properties of the sample. The measured absorption columns in the quasars are different than those in the galaxies in the sense that the quasars show no absorption (with limits 1021cm2\sim 10^{21} \rm cm^{-2}) while the galaxies have large absorption columns (>1022cm2> 10^{22} \rm cm^{-2}) consistent with previous findings. The median photon index of the sources with high S/N is Γ=1.84±0.24\Gamma=1.84 \pm0.24 and it is larger than the typical index of radio loud quasars. The arcsec resolution of {\it Chandra} telescope allows us to investigate X-ray extended emission, and look for diffuse components and X-ray jets. We found X-ray jets in two quasars (PKS 1127-145, B2 0738+32), an X-ray cluster surrounding a CSS quasar (z=1.1, 3C 186), detected a possible binary structure in 0941-080 galaxy and an extended diffuse emission in galaxy PKS B2 1345+12. We discuss our results in the context of X-ray emission processes and radio source evolution. We conclude that the X-ray emission in these sources is most likely unrelated to a relativistic jet, while the sources' radio-loudness may suggest a high radiative efficiency of the jet power in these sources.Comment: 15 pages, to be published in Ap
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