61 research outputs found

    Modeling the Large Scale Structures of Astrophysical Jets in the Magnetically Dominated Limit

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    We suggest a new approach that could be used for modeling both the large scale behavior of astrophysical jets and the magnetically dominated explosions in astrophysics. We describe a method for modeling the injection of magnetic fields and their subsequent evolution in a regime where the free energy is magnetically dominated. The injected magnetic fields, along with their associated currents, have both poloidal and toroidal components, and they are not force free. The dynamic expansion driven by the Lorentz force of the injected fields is studied using 3-dimensional ideal magnetohydrodynamic simulations. The generic behavior of magnetic field expansion, the interactions with the background medium, and the dependence on various parameters are investigated.Comment: Accepted to ApJ, May 10, 2006 issue, 12 figures total (3 color figures

    Enabling community-based metrology for wood-degrading fungi

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    Background: Lignocellulosic biomass could support a greatly-expanded bioeconomy. Current strategies for using biomass typically rely on single-cell organisms and extensive ancillary equipment to produce precursors for downstream manufacturing processes. Alternative forms of bioproduction based on solid-state fermentation and wood-degrading fungi could enable more direct means of manufacture. However, basic methods for cultivating wood-degrading fungi are often ad hoc and not readily reproducible. Here, we developed standard reference strains, substrates, measurements, and methods sufficient to begin to enable reliable reuse of mycological materials and products in simple laboratory settings. Results: We show that a widely-available and globally-regularized consumer product (Pringles™) can support the growth of wood-degrading fungi, and that growth on Pringles™-broth can be correlated with growth on media made from a fully-traceable and compositionally characterized substrate (National Institute of Standards and Technology Reference Material 8492 Eastern Cottonwood Whole Biomass Feedstock). We also establish a Relative Extension Unit (REU) framework that is designed to reduce variation in quantification of radial growth measurements. So enabled, we demonstrate that five laboratories were able to compare measurements of wood-fungus performance via a simple radial extension growth rate assay, and that our REU-based approach reduced variation in reported measurements by up to ~ 75%. Conclusions: Reliable reuse of materials, measures, and methods is necessary to enable distributed bioproduction processes that can be adopted at all scales, from local to industrial. Our community-based measurement methods incentivize practitioners to coordinate the reuse of standard materials, methods, strains, and to share information supporting work with wood-degrading fungi

    High Magnetic Shear Gain in a Liquid Sodium Stable Couette Flow Experiment; A Prelude to an alpha-Omega Dynamo

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    The Ω\Omega-phase of the liquid sodium α\alpha-Ω\Omega dynamo experiment at NMIMT in cooperation with LANL has successfully demonstrated the production of a high toroidal field, Bϕ≃8×BrB_{\phi} \simeq 8\times B_r from the radial component of an applied poloidal magnetic field, BrB_r. This enhanced toroidal field is produced by rotational shear in stable Couette flow within liquid sodium at Rm≃120Rm \simeq 120. The small turbulence in stable Taylor-Couette flow is caused by Ekman flow where (δv/v)2∼10−3 (\delta v/v)^2 \sim 10^{-3} . This high Ω\Omega-gain in low turbulence flow contrasts with a smaller Ω\Omega-gain in higher turbulence, Helmholtz-unstable shear flows. This result supports the ansatz that large scale astrophysical magnetic fields are created within semi-coherent large scale motions in which turbulence plays only a smaller diffusive role that enables magnetic flux linkage.Comment: 5 pages, 5 figures, submitted PRL revised version: add one author, minor typo'

    Security of Energy Supply: Comparing Scenarios from a European Perspective

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