3,698 research outputs found

    Some bog denizens

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    Tucked away in the bogs and swamps of Wisconsin, and in similar habitats throughout the world, thrive a myriad of unicellular plants known as Desmids. They are among the most aesthetic of all microorganisms and vie with the glassywalled Diatoms as Jewel Plants. If it were not for the inquisitive biologist and the students of the microscopic cosmos, Desmids well might exist unnoticed. For although they have highly intriguing biological features they play no role in water spoilage problems, nor are they important in the food cycle of aquatic animals. Hence they do not attract attention nor invite the condemnations that are directed toward some other groups of algae such as the blue-greens

    A Brief Summary of Work on Iowa Algae

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    My part in the taxonomic survey of the algal flora of Iowa began in the fall of 1924. It may be of interest at this time to summarize briefly the work done on the algae of Iowa, including my unpublished notes

    Serenade

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    https://digitalcommons.library.umaine.edu/mmb-me/1633/thumbnail.jp

    Longitudinal Polarization at future e+e−e^+e^- Colliders and Virtual New Physics Effects

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    The theoretical merits of longitudinal polarization asymmetries of electron-positron annihilation into two final fermions at future colliders are examined, using a recently proposed theoretical description. A number of interesting features, valid for searches of virtual effects of new physics, is underlined, that is reminiscent of analogous properties valid on top of ZZ resonance. As an application to a concrete example, we consider the case of a model with triple anomalous gauge couplings and show that the additional information provided by these asymmetries would lead to a drastic reduction of the allowed domain of the relevant parameters.Comment: 18 pages and 1 figure. e-mail: [email protected]

    The Buckland Park air shower array

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    The new Buckland Park Air Shower Array has been producing analyzed shower data since July 1984. The array is described and some preliminary performance figures are presented

    Electroweak Radiative Corrections To Polarized M{\o}ller Scattering Asymmetries

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    One loop electroweak radiative corrections to left-right parity violating M{\o}ller scattering (e−e−→e−e−e^-e^-\to e^-e^-) asymmetries are presented. They reduce the standard model (tree level) prediction by 40±3\pm 3 \% where the main shift and uncertainty stem from hadronic vacuum polarization loops. A similar reduction also occurs for the electron-electron atomic parity violating interaction. That effect can be attributed to an increase of sin⁥2ΞW(q2)\sin^2\theta_W(q^2) by 3%3\% in running from q2=mZ2q^2=m_Z^2 to 0. The sensitivity of the asymmetry to ``new physics'' is also discussed.Comment: 14 pages, Revtex, postscript file including figures is available at ftp://ttpux2.physik.uni-karlsruhe.de/ttp95-14/ttp95-14.ps or via WWW at http://ttpux2.physik.uni-karlsruhe.de/cgi-bin/preprints/ (129.13.102.139

    The Intrinsically X-ray Weak Quasar PHL 1811. I. X-ray Observations and Spectral Energy Distribution

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    This is the first of two papers reporting observations and analysis of the unusually bright (m_b=14.4), luminous (M_B=-25.5), nearby (z=0.192) narrow-line quasar PHL 1811, focusing on the X-ray properties and the spectral energy distribution. Two Chandra observations reveal a weak X-ray source with a steep spectrum. Variability by a factor of 4 between the two observations separated by 12 days suggest that the X-rays are not scattered emission. The XMM-Newton spectra are modelled in the 0.3--5 keV band by a steep power law with \Gamma = 2.3\pm 0.1, and the upper limit on intrinsic absorption is 8.7 x 10^{20} cm^{-2}. The spectral slopes are consistent with power law indices commonly observed in NLS1s, and it appears that we observe the central engine X-rays directly. Including two recent Swift ToO snapshots, a factor of ~5 variability was observed among the five X-ray observations reported here. In contrast, the UV photometry obtained by the XMM-Newton OM and Swift UVOT, and the HST spectrum reveal no significant UV variability. The \alpha_{ox} inferred from the Chandra and contemporaneous HST spectrum is -2.3 \pm 0.1, significantly steeper than observed from other quasars of the same optical luminosity. The steep, canonical X-ray spectra, lack of absorption, and significant X-ray variability lead us to conclude that PHL 1811 is intrinsically X-ray weak. We also discuss an accretion disk model, and the host galaxy of PHL 1811.Comment: 45 pages, 9 figures, accepted for publication in Ap
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