255 research outputs found

    Teleomorph and Anamorph Relationships in Marine Ascomycetes (Halosphaeriaceae)

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    Studies of the halosphaeriaceous fungi revealed six teleomorph-anamorph relationships: Corollospora pulchella - Clavariopsis bulbosa, Corollospora luteola - Sigmoidea luteola, Corollospora intermedia - Varicosporina sp., Halosphaeria mediosetigera - Trichocladium achrasporum, Halosphaeria cucullata – Periconia prolifica and Lindra obtusa - Anguillospora marina. A number of characters have been used in the taxonomy of the Halosphaeriaceae. Recently, particular attention has been devoted to ascospore appendage ontogeny. ln this paper we examine ascospore ontogeny, conidial development of anamorphs and the peridial structure of the ascocarps. The latter, along with ascospore appendage ontogeny, have been found to be stable characters and can be used in the separation of genera within the Halosphaeriaceae. In addition, the geographical distribution of several marine fungi was found to be related to their morphs as follows; those strains with only teleomorphs are distributed in the lower temperature regions, those with anamorphs only in the higher temperature regions while those with teleomorphs and anamorphs are distributed in the intermediate regions. Seasonal alternation of morphs was also observed in C. intermedia; the teleomorph occurring predominantly during the winter and the anamorph during spring through to the autumn

    Solar Neutron Events of October-November 2003

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    During the period when the Sun was intensely active on October-November 2003, two remarkable solar neutron events were observed by the ground-based neutron monitors. On October 28, 2003, in association with an X17.2 large flare, solar neutrons were detected with high statistical significance (6.4 sigma) by the neutron monitor at Tsumeb, Namibia. On November 4, 2003, in association with an X28 class flare, relativistic solar neutrons were observed by the neutron monitors at Haleakala in Hawaii and Mexico City, and by the solar neutron telescope at Mauna Kea in Hawaii simultaneously. Clear excesses were observed at the same time by these detectors, with the significance calculated as 7.5 sigma for Haleakala, and 5.2 sigma for Mexico City. The detector onboard the INTEGRAL satellite observed a high flux of hard X-rays and gamma-rays at the same time in these events. By using the time profiles of the gamma-ray lines, we can explain the time profile of the neutron monitor. It appears that neutrons were produced at the same time as the gamma-ray emission.Comment: 35 pages, 21 figures, accepted for publication in Ap

    Search for the Pair Production of Dark Particles XX with KL0XXK_L^0 \to XX, XγγX \to \gamma\gamma

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    We present the first search for the pair production of dark particles XX via KL0XXK_L^0\to XX with XX decaying into two photons using the data collected by the KOTO experiment. No signal was observed in the mass range of 40 - 110~MeV/c2^2 and 210 - 240 MeV/c2^2. This sets upper limits on the branching fractions as B(KL0XX)\mathcal{B}(K_L^0 \to XX) << (1-4) ×\times 107^{-7} and B(KL0XX)\mathcal{B}(K_L^0 \to XX) << (1-2) ×\times 106^{-6} at the 90% confidence level for the two mass regions, respectively

    The Palomar Testbed Interferometer Calibrator Catalog

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    The Palomar Testbed Interferometer (PTI) archive of observations between 1998 and 2005 is examined for objects appropriate for calibration of optical long-baseline interferometer observations - stars that are predictably point-like and single. Approximately 1,400 nights of data on 1,800 objects were examined for this investigation. We compare those observations to an intensively studied object that is a suitable calibrator, HD217014, and statistically compare each candidate calibrator to that object by computing both a Mahalanobis distance and a Principal Component Analysis. Our hypothesis is that the frequency distribution of visibility data associated with calibrator stars differs from non-calibrator stars such as binary stars. Spectroscopic binaries resolved by PTI, objects known to be unsuitable for calibrator use, are similarly tested to establish detection limits of this approach. From this investigation, we find more than 350 observed stars suitable for use as calibrators (with an additional 140\approx 140 being rejected), corresponding to 95\gtrsim 95% sky coverage for PTI. This approach is noteworthy in that it rigorously establishes calibration sources through a traceable, empirical methodology, leveraging the predictions of spectral energy distribution modeling but also verifying it with the rich body of PTI's on-sky observations.Comment: 100 pages, 7 figures, 7 tables; to appear in the May 2008ApJS, v176n

    Angiotensin II receptor expression and relation to Helicobacter pylori-infection in the stomach of the Mongolian gerbil

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    <p>Abstract</p> <p>Background</p> <p>The role of the renin-angiotensin system in gastric physiology and disease has as yet been sparsely explored. The first aim of the study was to investigate the baseline presence and location of angiotensin II receptors (AT1R and AT2R) in the stomach of the Mongolian gerbil. A second aim was to elucidate whether the presence of <it>H. pylori </it>infection is associated with changes in the expression of these receptors.</p> <p>Methods</p> <p><it>H. pylori</it>-negative and <it>H. pylori-</it>infected (strain SS1 or TN2GF4) male Mongolian gerbils were investigated. The stomachs were examined at six or 12 months after inoculation by the use of immunohistochemistry, western blot and microscopic morphometry.</p> <p>Results</p> <p>AT1R and AT2R were located in a variety of cells in the gerbil gastric wall, including a subpopulation of endocrine cells in the antral mucosa and inflammatory cells infiltrating <it>H. pylori</it>-infected stomachs. Gerbils infected with the SS1 strain showed a significantly increased antral AT1R protein expression and an increased number of infiltrating polymorphonuclear leucocytes (PMNs) at 12 months. The AT1R protein expression correlated with the number of PMNs and the antral expression of myeloperoxidase.</p> <p>Conclusions</p> <p>Angiotensin II receptors are present in a variety of cells in the gastric wall of the Mongolian gerbil. The results indicate an influence dependent on the <it>H. pylori </it>strain on the gastric AT1R expression and a relationship between gastric AT1R expression and mucosal PMNs infiltration.</p

    Search for Cosmic-ray Boosted Sub-GeV Dark Matter using Recoil Protons at Super-Kamiokande

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    We report a search for cosmic-ray boosted dark matter with protons using the 0.37 megaton×\timesyears data collected at Super-Kamiokande experiment during the 1996-2018 period (SKI-IV phase). We searched for an excess of proton recoils above the atmospheric neutrino background from the vicinity of the Galactic Center. No such excess is observed, and limits are calculated for two reference models of dark matter with either a constant interaction cross-section or through a scalar mediator. This is the first experimental search for boosted dark matter with hadrons using directional information. The results present the most stringent limits on cosmic-ray boosted dark matter and exclude the dark matter-nucleon elastic scattering cross-section between 1033 cm210^{-33}\text{ cm}^{-2} and 1027 cm210^{-27}\text{ cm}^{-2} for dark matter mass from 10 MeV/c2c^2 to 1 GeV/c2c^2.Comment: With 1-page appendi

    Measurement of the cosmogenic neutron yield in Super-Kamiokande with gadolinium loaded water

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    Cosmic-ray muons that enter the Super-Kamiokande detector cause hadronic showers due to spallation in water, producing neutrons and radioactive isotopes. Those are a major background source for studies of MeV-scale neutrinos and searches for rare events. Since 2020, gadolinium was introduced in the ultra-pure water in the Super-Kamiokande detector to improve the detection efficiency of neutrons. In this study, the cosmogenic neutron yield was measured using data acquired during the period after the gadolinium loading. The yield was found to be (2.76±0.02(stat.)±0.19(syst.))×104μ1g1cm2(2.76 \pm 0.02\,\mathrm{(stat.) \pm 0.19\,\mathrm{(syst.)}}) \times 10^{-4}\,\mu^{-1} \mathrm{g^{-1} cm^{2}} at 259 GeV of average muon energy at the Super-Kamiokande detector.Comment: 10 pages, 10 figures, 3 table
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