2,522 research outputs found

    Infrared weak corrections to strongly interacting gauge bosons scattering

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    We evaluate the impact of electroweak corrections of infrared origin on longitudinal strongly interacting gauge bosons scattering, calculating all order resummed expressions at the double log level. As a working example, we consider the Standard model with a heavy Higgs. At energies typical of forthcoming experiments (LHC,ILC,CLIC), the corrections are in the 10-40 % range, the relative sign depending on the initial state considered and on whether or not additional gauge bosons emission is included.Comment: 13 pages, 6 figure

    Diffuse cosmic rays shining in the Galactic center: A novel interpretation of H.E.S.S. and Fermi-LAT gamma-ray data

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    We present a novel interpretation of the γ\gamma-ray diffuse emission measured by Fermi-LAT and H.E.S.S. in the Galactic center (GC) region and the Galactic ridge (GR). In the first part we perform a data-driven analysis based on PASS8 Fermi-LAT data: we extend down to few GeV the spectra measured by H.E.S.S. and infer the primary cosmic-ray (CR) radial distribution between 0.1 and 3 TeV. In the second part we adopt a CR transport model based on a position-dependent diffusion coefficient. Such behavior reproduces the radial dependence of the CR spectral index recently inferred from the Fermi-LAT observations. We find that the bulk of the GR emission can be naturally explained by the interaction of the diffuse steady-state Galactic CR sea with the gas present in the Central Molecular Zone. Although our results leave room for a residual radial-dependent emission associated with a central source, the relevance of the large-scale background prevents from a solid evidence of a GC Pevatron.Comment: 5 pages, 3 figures, accepted for publication in Physical Review Letter

    Hard Cosmic Ray Sea in the Galactic Center: a consistent interpretation of H.E.S.S. and Fermi-LAT γ\gamma-ray data

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    We present a novel interpretation of the gamma-ray diffuse emission measured by H.E.S.S. in the Galactic Center (GC) region and the Galactic ridge. Our starting base is an updated analysis of PASS8 Fermi-LAT data, which allows to extend down to few GeV the spectra measured by H.E.S.S. and to infer the primary CR radial distribution above 100 GeV. We compare those results with a CR transport model assuming a harder scaling of the diffusion coefficient with rigidity in the inner Galaxy. Such a behavior reproduces the radial dependence of the CR spectral index recently inferred from Fermi-LAT measurements in the inner GP. We find that, in this scenario, the bulk of the Galactic ridge emission can be naturally explained by the interaction of the diffuse, steady-state Galactic CR sea interacting with the gas present in the Central molecular zone. The evidence of a GC PeVatron is significantly weaker than that inferred adopting a conventional (softer) CR sea.Comment: Oral contribution to the International Cosmic Ray Conference (ICRC 2017), 12-20 July 2017, Bexco, Busan, Kore

    Search for partial resistance to leaf rust in a collection of ancient Spanish wheats

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    A collection of 917 accessions of Spanish durum and bread wheat was screened for resistance to leaf rust (Puccinia triticina) under field conditions at three locations. Resistance levels ranged from very low to very high, high susceptibility being most frequent. Relative disease severity (referred to the most susceptible accession = 100 %) was lower than 20 % in about 6 % of the accessions in each location. In the collection most of the lines (84 %)displayed a susceptible infection type. A final selection of seven accessions (one of them durum) displaying low severity level in the field and high infection type in a growth chamber was chosen for further studies. High levels of partial resistant with longer latency period and high percentage of early aborted colonies without necrosis were found. They might be used in breeding programmes

    CAR: A MATLAB Package to Compute Correspondence Analysis with Rotations

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    Correspondence analysis (CA) is a popular method that can be used to analyse relationships between categorical variables. Like principal component analysis, CA solutions can be rotated both orthogonally and obliquely to simple structure without affecting the total amount of explained inertia. We describe a MATLAB package for computing CA. The package includes orthogonal and oblique rotation of axes. It is designed not only for advanced users of MATLAB but also for beginners. Analysis can be done using a user-friendly interface, or by using command lines. We illustrate the use of CAR with one example.

    Influence of the strong metal support interaction effect (SMSI) of Pt/TiO2 and Pd/TiO2 systems in the photocatalytic biohydrogen production from glucose solution

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    Two different catalysts consisting of Pt/TiO2 and Pd/TiO 2 were submitted to diverse oxidative and reductive calcination treatments and tested for photocatalytic reforming of glucose water solution (as a model of biomass component) in H2 production. Oxidation and reduction at 850°C resulted in better photocatalysts for hydrogen production than Degussa P-25 and the ones prepared at 500°C, despite the fact that the former consisted in very low surface area (6-8 m2/g) rutile titania specimens. The platinum-containing systems prepared at 850°C give the most effective catalysts. XPS characterization of the systems showed that thermal treatment at 850°C resulted in electron transfer from titania to metal particles through the so-called strong metal-support interaction (SMSI) effect. Furthermore, the greater the SMSI effect, the better the catalytic performance. Improvement in photocatalytic behavior is explained in terms of avoidance of electron-hole recombination through the electron transfer from titania to metal particles

    Incorporating Digital Tools with Ceramic Crafting: Design and Fabrication of Light Diffusing Screen Shells

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    This paper investigates the possibilities which arise by incorporating digital tools into the design and fabrication of ceramic building components. In particular, we present how traditional ceramic crafting fabrication methods could be enriched by using parametric, performative and generative design techniques alongside digital fabrication technologies. Considering the growing importance of ceramic components in architectural construction due to their economic and environmentally friendly properties, this paper highlights the findings of design-led research explorations, demonstrating potential innovative solutions and failures arising through a digitalised ‘file to factory’ design approach

    Gradual transition from insulator to semimetal of Ca1−x_{1-x}Eux_{x}B6_{6} with increasing Eu concentration

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    The local environment of Eu2+^{2+} (4f74f^{7}, S=7/2S=7/2) in Ca1−x_{1-x}Eux_{x}B6_{6} (0.003⩽x⩽1.000.003\leqslant x\leqslant 1.00) is investigated by means of electron spin resonance (ESR). For x≲0.003x\lesssim 0.003 the spectra show resolved \textit{fine} and \textit{hyperfine} structures due to the cubic crystal \textit{electric} field and nuclear \textit{hyperfine} field, respectively. The resonances have Lorentzian line shape, indicating an \textit{insulating} environment for the Eu2+^{2+} ions. For 0.003≲x≲0.070.003\lesssim x\lesssim 0.07, as xx increases, the ESR lines broaden due to local distortions caused by the Eu/Ca ions substitution. For 0.07≲x≲0.300.07\lesssim x\lesssim 0.30, the lines broaden further and the spectra gradually change from Lorentzian to Dysonian resonances, suggesting a coexistence of both \textit{insulating} and \textit{metallic} environments for the Eu2+^{2+} ions. In contrast to Ca1−x_{1-x}Gdx_{x}B6_{6}, the \textit{fine} structure is still observable up to x≈0.15x\approx 0.15. For x≳0.30x\gtrsim 0.30 the \textit{fine} and \textit{hyperfine} structures are no longer observed, the line width increases, and the line shape is purely Dysonian anticipating the \textit{semimetallic} character of EuB6_{6}. This broadening is attributed to a spin-flip scattering relaxation process due to the exchange interaction between conduction and Eu2+^{2+} 4f4f electrons. High field ESR measurements for x≳0.15x\gtrsim 0.15 reveal smaller and anisotropic line widths, which are attributed to magnetic polarons and Fermi surface effects, respectively.Comment: Submitted to PR
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