774 research outputs found

    Crystal structure of 4,4-dimethyl-2-(trifluoromethyl)-4,5-dihydro-1H-imidazole, C6H9F3N2

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    C6H9F3N2, monoclinic, P21/n (no. 14), a = 10.6224(9) Å, b = 11.8639(9) Å, c = 13.3139(11) Å, β = 105.903(3)°, V = 1613.6(2) Å3, Z = 8, Rgt(F) = 0.0618, wRref(F2) = 0.1629, T = 102(2) K [1–3]

    Toward Five-dimensional Core-collapse Supernova Simulations

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    The computational difficulty of six-dimensional neutrino radiation hydrodynamics has spawned a variety of approximations, provoking a long history of uncertainty in the core-collapse supernova explosion mechanism. Under the auspices of the Terascale Supernova Initiative, we are honoring the physical complexity of supernovae by meeting the computational challenge head-on, undertaking the development of a new adaptive mesh refinement code for self-gravitating, six-dimensional neutrino radiation magnetohydrodynamics. This code--called {\em GenASiS,} for {\em Gen}eral {\em A}strophysical {\em Si}mulation {\em S}ystem--is designed for modularity and extensibility of the physics. Presently in use or under development are capabilities for Newtonian self-gravity, Newtonian and special relativistic magnetohydrodynamics (with `realistic' equation of state), and special relativistic energy- and angle-dependent neutrino transport--including full treatment of the energy and angle dependence of scattering and pair interactions.Comment: 5 pages. Proceedings of SciDAC 2005, Scientific Discovery through Advanced Computing, San Francisco, CA, 26-30 June 200

    A logical layer to interpret user interactions

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    Some computing user interfaces include a large number of user-selectable options which can make it difficult for a user to locate the right option. Another frequent user interface problem is inadvertent or unintended invocation of actions, e.g., by selection of an incorrect icon from two icons placed close to each other. In some user interfaces, simple actions sometimes require a disproportionately tedious sequence of interactions. This disclosure introduces a layer between the user and the application such that user commands or interactions are interpreted in light of past interactions, and corrected, filtered or automated as appropriate. Past interactions are utilized, and interpretation or corrective action is performed only upon permission from the user. For ease of interaction, such permission is obtained, e.g., at initial setup, and is modifiable

    Advancing Nucleosynthesis in Self-consistent, Multidimensional Models of Core-Collapse Supernovae

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    We investigate core-collapse supernova (CCSN) nucleosynthesis in polar axisymmetric simulations using the multidimensional radiation hydrodynamics code CHIMERA. Computational costs have traditionally constrained the evolution of the nuclear composition in CCSN models to, at best, a 14-species α\alpha-network. Such a simplified network limits the ability to accurately evolve detailed composition, neutronization and the nuclear energy generation rate. Lagrangian tracer particles are commonly used to extend the nuclear network evolution by incorporating more realistic networks in post-processing nucleosynthesis calculations. Limitations such as poor spatial resolution of the tracer particles, estimation of the expansion timescales, and determination of the "mass-cut" at the end of the simulation impose uncertainties inherent to this approach. We present a detailed analysis of the impact of these uncertainties on post-processing nucleosynthesis calculations and implications for future models.Comment: Proceedings of the 13th Symposium on Nuclei in the Cosmos. 7-11 July 2014. Debrecen, Hungar
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