232 research outputs found

    Realistic Simulation of Local Solar Supergranulation

    Full text link
    I represent results three-dimensional numerical simulation of solar surface convection on scales local supergranulation with realistic model physics. I study thermal structure of convective motions in photosphere, the range of convection cell sizes and the penetration depths of convection. A portion of the solar photosphere extending 100 x 100 Mm horizontally and from 0 Mm down to 20 Mm below the visible surface is considered. I take equation of state and opacities of stellar matter and distribution with radius of all physical variables from Solar Standard Model. The equations of fully compressible radiation hydrodynamics with dynamical viscosity and gravity are solved. The high order conservative PPML difference scheme for the hydrodynamics, the method of characteristic for the radiative transfer and dynamical viscosity from subgrid scale modeling are applied. The simulations are conducted on a uniform horizontal grid of 1000 x 1000, with 168 nonuniformly spaced vertical grid points, on 256 processors with distributed memory multiprocessors on supercomputer MVS5000 in Computational Centre of Russian Academy of Sciences.Comment: 4 pages, 3 figures. To appear in AIP Conference Proceedings, "Exploring the Solar System and the Universe", Apr 8-12 2008, Bucharest, Romania, eds. Vasile Mioc, Cristiana Dumitrache & Nedelia A. Popesc

    Transgenic miR156 Switchgrass in the Field: Growth, Recalcitrance and Rust Susceptibility

    Get PDF
    Sustainable utilization of lignocellulosic perennial grass feedstocks will be enabled by high biomass production and optimized cell wall chemistry for efficient conversion into biofuels. MicroRNAs are regulatory elements that modulate the expression of genes involved in various biological functions in plants, including growth and development. In greenhouse studies, overexpressing a microRNA (miR156) gene in switchgrass had dramatic effects on plant architecture and flowering, which appeared to be driven by transgene expression levels. Highexpressing lines were extremely dwarfed, whereas low and moderate-expressing lines had higher biomass yields, improved sugar release and delayed flowering. Four lines with moderate or low miR156 overexpression from the prior greenhouse study were selected for a field experiment to assess the relationship between miR156 expression and biomass production over three years. We also analysed important bioenergy feedstock traits such as flowering, disease resistance, cell wall chemistry and biofuel production. Phenotypes of the transgenic lines were inconsistent between the greenhouse and the field as well as among different field growing seasons. One low expressing transgenic line consistently produced more biomass (25%–56%) than the control across all three seasons, which translated to the production of 30% more biofuel per plant during the final season. The other three transgenic lines produced less biomass than the control by the final season, and the two lines with moderate expression levels also exhibited altered disease susceptibilities. Results of this study emphasize the importance of performing multiyear field studies for plants with altered regulatory transgenes that target plant growth and development

    Performance of the CMS Cathode Strip Chambers with Cosmic Rays

    Get PDF
    The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

    Performance and Operation of the CMS Electromagnetic Calorimeter

    Get PDF
    The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented

    A focus on selected perspectives of the NUMEN project

    Get PDF
    The use of double charge exchange reactions is discussed in view of their application to extract information that may be helpful to determinate the nuclear matrix elements entering in the expression of neutrinoless double beta decay half-life. The strategy adopted in the experimental campaigns performed at INFN - Laboratori Nazionali del Sud and in the analysis methods within the NUMEN project is briefly described, emphasizing the advantages of the multi-channel approach to nuclear reaction data analysis. An overview on the research and development activities on the MAGNEX magnetic spectrometer is also given, with a focus on the chosen technological solutions for the focal plane detector which will guarantee the performances at high-rate conditions

    Performance studies of the CMS strip tracker before installation

    Get PDF
    Peer reviewe

    Calibration of the CMS Drift Tube Chambers and Measurement of the Drift Velocity with Cosmic Rays

    Get PDF
    Peer reviewe

    CMS Data Processing Workflows during an Extended Cosmic Ray Run

    Get PDF
    Peer reviewe
    • …
    corecore