1,868 research outputs found

    Supernova dust for the extinction law in a young infrared galaxy at z = 1

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    We apply the supernova(SN) extinction curves to reproduce the observed properties of SST J1604+4304 which is a young infrared (IR) galaxy at z = 1. The SN extinction curves used in this work were obtained from models of unmixed ejecta of type II supernovae(SNe II) for the Salpeter initial mass function (IMF) with a mass range from 8 to 30 M_sun or 8 to 40 M_sun. The effect of dust distributions on the attenuation of starlight is investigated by performing the chi-square fitting method against various dust distributions. These are the commonly used uniform dust screen, the clumpy dust screen, and the internal dust geometry. We add to these geometries three scattering properties, namely, no-scattering, isotropic scattering, and forward-only scattering. Judging from the chi-square values, we find that the uniform screen models with any scattering property provide good approximations to the real dust geometry. Internal dust is inefficient to attenuate starlight and thus cannot be the dominant source of the extinction. We show that the SN extinction curves reproduce the data of SST J1604+4304 comparable to or better than the Calzetti extinction curve. The Milky Way extinction curve is not in satisfactory agreement with the data unless several dusty clumps are in the line of sight. This trend may be explained by the abundance of SN-origin dust in these galaxies; SN dust is the most abundant in the young IR galaxy at z = 1, abundant in local starbursts, and less abundant in the Galaxy. If dust in SST J1604+4304 is dominated by SN dust, the dust production rate is about 0.1 M_sun per SN.Comment: 12 pages, 8 figures, 1 tabl

    Cosmological rotating black holes in five-dimensional fake supergravity

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    In recent series of papers, we found an arbitrary dimensional, time-evolving and spatially-inhomogeneous solutions in Einstein-Maxwell-dilaton gravity with particular couplings. Similar to the supersymmetric case the solution can be arbitrarily superposed in spite of non-trivial time-dependence, since the metric is specified by a set of harmonic functions. When each harmonic has a single point source at the center, the solution describes a spherically symmetric black hole with regular Killing horizons and the spacetime approaches asymptotically to the Friedmann-Lema\^itre-Robertson-Walker (FLRW) cosmology. We discuss in this paper that in 5-dimensions this equilibrium condition traces back to the 1st-order "Killing spinor" equation in "fake supergravity" coupled to arbitrary U(1) gauge fields and scalars. We present a 5-dimensional, asymptotically FLRW, rotating black-hole solution admitting a nontrivial "Killing spinor," which is a spinning generalization of our previous solution. We argue that the solution admits nondegenerate and rotating Killing horizons in contrast with the supersymmetric solutions. It is shown that the present pseudo-supersymmetric solution admits closed timelike curves around the central singularities. When only one harmonic is time-dependent, the solution oxidizes to 11-dimensions and realizes the dynamically intersecting M2/M2/M2-branes in a rotating Kasner universe. The Kaluza-Klein type black holes are also discussed.Comment: 24 pages, 2 figures; v2: references added, to appear in PR

    Observation of Conduction Band Satellite of Ni Metal by 3p-3d Resonant Inverse Photoemission Study

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    Resonant inverse photoemission spectra of Ni metal have been obtained across the Ni 3pp absorption edge. The intensity of Ni 3dd band just above Fermi edge shows asymmetric Fano-like resonance. Satellite structures are found at about 2.5 and 4.2 eV above Fermi edge, which show resonant enhancement at the absorption edge. The satellite structures are due to a many-body configuration interaction and confirms the existence of 3d8d^8 configuration in the ground state of Ni metal.Comment: 4 pages, 3 figures, submitted to Physical Review Letter

    Extreme ion heating in the dayside ionosphere in response to the arrival of a coronal mass ejection on 12 March 2012

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    Simultaneous measurements of the polar ionosphere with the European Incoherent Scatter (EISCAT) ultra high frequency (UHF) radar at Tromsø and the EISCAT Svalbard radar (ESR) at Longyearbyen were made during 07:00–12:00 UT on 12 March 2012. During the period, the Advanced Composition Explorer (ACE) spacecraft observed changes in the solar wind which were due to the arrival of coronal mass ejection (CME) effects associated with the 10 March M8.4 X-ray event. The solar wind showed two-step variations which caused strong ionospheric heating. First, the arrival of shock structures in the solar wind with enhancements of density and velocity, and a negative interplanetary magnetic field (IMF)-<i>B<sub>z</sub></i> component caused strong ionospheric heating around Longyearbyen; the ion temperature at about 300 km increased from about 1100 to 3400 K over Longyearbyen while that over Tromsø increased from about 1050 to 1200 K. After the passage of the shock structures, the IMF-<i>B<sub>z</sub></i> component showed positive values and the solar wind speed and density also decreased. The second strong ionospheric heating occurred after the IMF-<i>B<sub>z</sub></i> component showed negative values again; the negative values lasted for more than 1.5 h. This solar wind variation caused stronger heating of the ionosphere in the lower latitudes than higher latitudes, suggesting expansion of the auroral oval/heating region to the lower latitude region. This study shows an example of the CME-induced dayside ionospheric heating: a short-duration and very large rise in the ion temperature which was closely related to the polar cap size and polar cap potential variations as a result of interaction between the solar wind and the magnetosphere

    Adaptive regulation of membrane lipids and fluidity during thermal acclimation in Tetrahymena

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    The free-living eukaryotic protozoan Tetrahymena is a potentially useful model for the thermoadaptive membrane regulation because of easy growth in the axenic culture, systematic isolation of subcellular organelles, and quick response to temperature stress. Exposure of Tetrahymena cells to the cold temperature induces marked alterations in the lipid composition and the physical properties (fluidity) of various membranes. The increase in fatty acid unsaturation of membrane phospholipids is required to preserve the proper fluidity. In this homeoviscous adaptive response, acyl-CoA desaturase plays a pivotal role and its activity is regulated by induction of the enzyme via transcriptional activation

    Actinomycosis complicating sigmoid diverticular disease: a case report

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    A 63-year-old Caucasian woman was admitted to hospital as hypotensive with abdominal tenderness and vaginal discharge. Laboratory investigations showed microcytic anaemia, low albumin and high white cell count. Computerised tomography scans revealed small bowel dilatation, sigmoid diverticula, ascites and pelvic fluid. The endometrial pipelle was positive and vaginal swab was negative for actinomyces. Post mortem examination revealed widespread sigmoid diverticular disease and bowel perforation with an intense inflammation. Actinomycotic granules were noted in the diverticular inflammatory debris, pelvic abscess and lung sections. Clinical course and histomorphological findings favour the perforating sigmoid diverticular actinomycosis as an origin of the systemic infection

    Precise half-life measurement of 110Sn and 109In isotopes

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    The half-lives of 110Sn and 109In isotopes have been measured with high precision. The results are T1/2 =4.173 +- 0.023 h for 110Sn and T1/2 = 4.167 +-0.018 h for 109In. The precision of the half-lives has been increased by a factor of 5 with respect to the literature values which makes results of the recently measured 106Cd(alpha,gamma)110Sn and 106Cd(alpha,p)109In cross sections more reliable.Comment: 3 pages, 2 figures, accepted for publication in Phys. Rev C as brief repor

    The preg\u3csup\u3ec \u3c/sup\u3estrain of N. crassa has abnormal vesicles when grown on both low- and high-P\u3csub\u3ei\u3c/sub\u3e media

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    The genetic and molecular mechanisms controlling the synthesis of de-repressible phosphatases in Neurospora crassa include four regulatory genes, nuc-2, preg, pgov, and nuc-1, involved in a hierarchical relationship (Metzenberg, 1979. Microbiol. Rev. 43: 361-383)

    Dynamical model for Pion - Nucleon Bremsstrahlung

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    A dynamical model based on effective Lagrangians is proposed to describe the bremsstrahlung reaction πNπNγ \pi N \to \pi N \gamma at low energies. The Δ(1232)\Delta(1232) degrees of freedom are incorporated in a way consistent with both, electromagnetic gauge invariance and invariance under contact transformations. The model also includes the initial and final state rescattering of hadrons via a T-matrix with off-shell effects. The πNγ\pi N \gamma differential cross sections are calculated using three different T-matrix models and the results are compared with the soft photon approximation, and with experimental data. The aim of this analysis is to test the off-shell behavior of the different T-matrices under consideration.Comment: 16 pages, latex, 6 eps figures. Accepted for publication in Physical Review

    Can the magnetic moment contribution explain the A_y puzzle?

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    We evaluate the full one-photon-exchange Born amplitude for NdNd scattering. We include the contributions due to the magnetic moment of the proton or neutron, and the magnetic moment and quadrupole moment of the deuteron. It is found that the inclusion of the magnetic-moment interaction in the theoretical description of the NdNd scattering observables cannot resolve the long-standing AyA_y puzzle.Comment: 7 pages, 2 Postscript figures; to appear in Phys.Rev.
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