983 research outputs found

    Advances in the knowledge of the inocybe mixtilis group (Inocybaceae, Agaricomycetes), through molecular and morphological studies

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    Inocybe mixtilis constitutes a complex of species characterized by nodulose-angulose spores, absence of cortina and a more or less bulbous marginate stipe that is not darkening when desiccated. In order to elucidate species limits within the I. mixtilis complex, an ITS-RPB2 phylogeny was performed and interpreted using morphological and ecological characters. Six supported clades were obtained in our analyses that correspond to I. mixtilis, I. subtrivialis, and four new species to science: I. ceskae, I. johannis-stanglii, I. nothomixtilis and I. occulta. Species within this complex can be morphologically recognized through a unique combination of morphological characters, such as the spore shape, cystidial length and shape, presence and development of the velipellis and pileus colour and viscidity. Nevertheless, those characters overlap, especially among I. mixtilis, I. ceskae and I. occulta, and intermediate collections are therefore more reliably identified through ITS-sequencing. Two species, I. ceskae and I. occulta are present in both North America and Europe, while the rest are so far only known in Europe, or Europe and Asia (I. mixtilis). All species, except I. johannis-stanglii, seem to be able to establish ectomycorrhizal association both with conifers and angiosperms. Descriptions, colour illustrations and a key to all known species in the I. mixtilis group are provided

    A Cosmic Census of Radio Pulsars with the SKA

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    The Square Kilometre Array (SKA) will make ground breaking discoveries in pulsar science. In this chapter we outline the SKA surveys for new pulsars, as well as how we will perform the necessary follow-up timing observations. The SKA's wide field-of-view, high sensitivity, multi-beaming and sub-arraying capabilities, coupled with advanced pulsar search backends, will result in the discovery of a large population of pulsars. These will enable the SKA's pulsar science goals (tests of General Relativity with pulsar binary systems, investigating black hole theorems with pulsar-black hole binaries, and direct detection of gravitational waves in a pulsar timing array). Using SKA1-MID and SKA1-LOW we will survey the Milky Way to unprecedented depth, increasing the number of known pulsars by more than an order of magnitude. SKA2 will potentially find all the Galactic radio-emitting pulsars in the SKA sky which are beamed in our direction. This will give a clear picture of the birth properties of pulsars and of the gravitational potential, magnetic field structure and interstellar matter content of the Galaxy. Targeted searches will enable detection of exotic systems, such as the ~1000 pulsars we infer to be closely orbiting Sgr A*, the supermassive black hole in the Galactic Centre. In addition, the SKA's sensitivity will be sufficient to detect pulsars in local group galaxies. To derive the spin characteristics of the discoveries we will perform live searches, and use sub-arraying and dynamic scheduling to time pulsars as soon as they are discovered, while simultaneously continuing survey observations. The large projected number of discoveries suggests that we will uncover currently unknown rare systems that can be exploited to push the boundaries of our understanding of astrophysics and provide tools for testing physics, as has been done by the pulsar community in the past.Comment: 20 pages, 7 figures, to be published in: "Advancing Astrophysics with the Square Kilometre Array", Proceedings of Science, PoS(AASKA14)04

    Photon emission from bare quark stars

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    We investigate the photon emission from the electrosphere of a quark star. It is shown that at temperatures T\sim 0.1-1 MeV the dominating mechanism is the bremsstrahlung due to bending of electron trajectories in the mean Coulomb field of the electrosphere. The radiated energy for this mechanism is much larger than that for the Bethe-Heitler bremsstrahlung. The energy flux from the mean field bremsstrahlung exceeds the one from the tunnel e^{+}e^{-} pair creation as well. We demonstrate that the LPM suppression of the photon emission is negligible.Comment: 35 pages, 5 figure

    Meson loop effects in the NJL model at zero and non-zero temperature

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    We compare two different possibilities to include meson-loop corrections in the Nambu-Jona-Lasinio model: a strict 1/N_c-expansion in next-to-leading order and a non-perturbative scheme corresponding to a one-meson-loop approximation to the effective action. Both schemes are consistent with chiral symmetry, in particular with the Goldstone theorem and the Gell-Mann-Oakes-Renner relation. The numerical part at zero temperature focuses on the pion and the rho-meson sector. For the latter the meson-loop-corrections are crucial in order to include the dominant rho -> pipi-decay channel, while the standard Hartree + RPA approximation only contains unphysical qqbar-decay channels. We find that m_\pi, f_\pi, and quantities related to the rho-meson self-energy can be described reasonably with one parameter set in the 1/N_c-expansion scheme, whereas we did not succeed to obtain such a fit in the non-perturbative scheme. We also investigate the temperature dependence of the quark condensate. Here we find consistency with chiral perturbation theory to lowest order. Similarities and differences of both schemes are discussed.Comment: 51 pages, 18 figures, to be published in Physics of Atomic Nuclei, the volume dedicated to the 90th birthday of A.B. Migdal, error in Eq. 4.22 correcte

    Critical temperature for kaon condensation in color-flavor locked quark matter

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    We study the behavior of Goldstone bosons in color-flavor-locked (CFL) quark matter at nonzero temperature. Chiral symmetry breaking in this phase of cold and dense matter gives rise to pseudo-Goldstone bosons, the lightest of these being the charged and neutral kaons K^+ and K^0. At zero temperature, Bose-Einstein condensation of the kaons occurs. Since all fermions are gapped, this kaon condensed CFL phase can, for energies below the fermionic energy gap, be described by an effective theory for the bosonic modes. We use this effective theory to investigate the melting of the condensate: we determine the temperature-dependent kaon masses self-consistently using the two-particle irreducible effective action, and we compute the transition temperature for Bose-Einstein condensation. Our results are important for studies of transport properties of the kaon condensed CFL phase, such as bulk viscosity.Comment: 24 pages, 8 figures, v2: new section about effect of electric neutrality on critical temperature added; references added; version to appear in J.Phys.

    Local texture measurements with high-energy synchrotron radiation on NiAl deformed in torsion

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    Plastic deformation leads to crystallographic preferred orientations (texture) of the grains in a polycrystalline sample. Therefore, the study of these textures gives informations about the slip systems activated during the deformation. In this study the deformation of polycrystalline NiAl was done by torsion under confining pressure leading to crack-free samples with a well-defined strain gradient. NiAl, an ordered intermetallic alloy with B2 structure, is a potential material candidate for high-temperature applications. Polycrystalline NiAl cylindrical samples with two different initial textures were deformed in torsion tests at 1000 K and 1273 K, respectively, in a Paterson-type rock deformation machine [1] under 400 MPa argon confining pressure. The diameter and height of the samples were 10 mm. The applied torsion leads to a simple shear in the tangential direction in a plane normal to the torsion axis. The shear strain and the shear strain rate in the samples increase linearly from zero at the torsion axis to a maximum ( ) at the sample edge. To investigate the local textures between the torsion axis and the edge, small pins with a diameter of 1 mm were prepared in the radial direction for each of the four deformed samples Quantitative texture measurements were performed with high-energy (100 keV) synchrotron radiation at the beamline BW5 [2], The incident monochromatic beam was defined by a slit system to 1 mm x 2 mm. The small pins were mounted in the Eulerian cradle parallel to the rotation axis ω. An image plate detector was positioned perpendicularly to the diffracted beam at a distance from the sample of about 1.3 m. Thus, the Debye-Scherrer rings with the indices (100), The texture was measured as a function of the shear strain at five different positions between Îł = 0 and 3. The samples deformed at 1273 K showed a poor grain statistics due to a large grain size. The corresponding pole figures are not shown here. The torsion deformation at 1000 K leads to much smaller grains. The corresponding (100) pole figures are shown for Îł = 1.5; 2.3 and 3 and two different initial texture

    Distinctive waves of innate immune response in the retina in experimental autoimmune encephalomyelitis

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    Neurodegeneration mediates neurological disability in inflammatory demyelinating diseases of the CNS. The role of innate immune cells in mediating this damage has remained controversial with evidence for destructive and protective effects. This has complicated efforts to develop treatment. The time sequence and dynamic evolution of the opposing functions are especially unclear. Given limits of in vivo monitoring in human diseases such as multiple sclerosis (MS), animal models are warranted to investigate the association and timing of innate immune activation with neurodegeneration. Using noninvasive in vivo retinal imaging of experimental autoimmune encephalitis (EAE) in CX3CR1GFP/+–knock-in mice followed by transcriptional profiling, we are able to show 2 distinct waves separated by a marked reduction in the number of innate immune cells and change in cell morphology. The first wave is characterized by an inflammatory phagocytic phenotype preceding the onset of EAE, whereas the second wave is characterized by a regulatory, antiinflammatory phenotype during the chronic stage. Additionally, the magnitude of the first wave is associated with neuronal loss. Two transcripts identified — growth arrest–specific protein 6 (GAS6) and suppressor of cytokine signaling 3 (SOCS3) — might be promising targets for enhancing protective effects of microglia in the chronic phase after initial injury
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