2,385 research outputs found

    Arkansas Corn and Grain Sorghum Performance Tests 2003

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    Corn and grain sorghum performance tests are conducted each year in Arkansas by the University of Arkansas Division of Agriculture. The tests provide information to companies marketing seed within the state, and aid the Arkansas Cooperative Extension Service in formulating recommendations for producers

    Coping with Persistent Pain, Effectiveness Research into Self-management (COPERS): statistical analysis plan for a randomised controlled trial

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    This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated

    Characterizing Supernova Progenitors via the Metallicities of their Host Galaxies, from Poor Dwarfs to Rich Spirals

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    We investigate how the different types of supernovae are relatively affected by the metallicity of their host galaxy. We match the SAI Supernova Catalog to the SDSS-DR4 catalog of star-forming galaxies with measured metallicities. These supernova host galaxies span a range of oxygen abundance from 12 + log(O/H) = 7.9 to 9.3 (~ 0.1 to 2.7 solar) and a range in absolute magnitude from MB = -15.2 to -22.2. To reduce the various observational biases, we select a subsample of well-characterized supernovae in the redshift range from 0.01 to 0.04, which leaves us with 58 SN II, 19 Ib/c, and 38 Ia. We find strong evidence that SN Ib/c are occurring in higher-metallicity host galaxies than SN II, while we see no effect for SN Ia relative to SN II. We note some extreme and interesting supernova-host pairs, including the metal-poor (~ 1/4 solar) host of the recent SN Ia 2007bk, where the supernova was found well outside of this dwarf galaxy. To extend the luminosity range of supernova hosts to even fainter galaxies, we also match all the historical supernovae with z < 0.3 to the SDSS-DR6 sky images, resulting in 1225 matches. This allows us to identify some even more extreme cases, such as the recent SN Ic 2007bg, where the likely host of this hypernova-like event has an absolute magnitude MB ~ -12, making it one of the least-luminous supernova hosts ever observed. This low-luminosity host is certain to be very metal poor (~ 1/20 solar), and therefore this supernova is an excellent candidate for association with an off-axis GRB. The two catalogs that we have constructed are available online and will be updated regularly. Finally, we discuss various implications of our findings for understanding supernova progenitors and their host galaxies.Comment: ApJ accepted, 26 pages, 5 figures, 1 table. Updated catalogs are available at http://www.astronomy.ohio-state.edu/~prieto/snhosts

    Phonon anomalies due to strong electronic correlations in layered organic metals

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    We show how the coupling between the phonons and electrons in a strongly correlated metal can result in phonon frequencies which have a non-monotonic temperature dependence. Dynamical mean-field theory is used to study the Hubbard-Holstein model that describes the \kappa-(BEDT-TTF)_2 X family of superconducting molecular crystals. The crossover with increasing temperature from a Fermi liquid to a bad metal produces phonon anomalies that are consistent with recent Raman scattering and acoustic experiments.Comment: 6 pages, 3 eps figure

    Quantum Transport Simulation of the DOS function, Self-Consistent Fields and Mobility in MOS Inversion Layers

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    We describe a simulation of the self-consistent fields and mobility in (100) Si-inversion layers for arbitrary inversion charge densities and temperatures. A nonequilibrium Green's functions formalism is employed for the state broadening and conductivity. The subband structure of the inversion layer electrons is calculated self-consistently by simultaneously solving the Schrödinger, Poisson and Dyson equations. The self-energy contributions from the various scattering mechanisms are calculated within the self-consistent Born approximation. Screening is treated within RPA. Simulation results suggest that the proposed theoretical model gives mobilities which are in excellent agreement with the experimental data

    The origin of the phase separation in partially deuterated κ\kappa-(ET)2_2Cu[N(CN)2_2]Br studied by infrared magneto-optical imaging spectroscopy

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    The direct observation of the phase separation between the metallic and insulating states of 75 %-deuterated κ\kappa-(ET)2_2Cu[N(CN)2_2]Br (d33d33) using infrared magneto-optical imaging spectroscopy is reported, as well as the associated temperature, cooling rate, and magnetic field dependencies of the separation. The distribution of the center of spectral weight () of d33d33 did not change under any of the conditions in which data were taken and was wider than that of the non-deuterated material. This result indicates that the inhomogenity of the sample itself is important as part of the origin of the metal - insulator phase separation.Comment: 4 pages, 3 figures, accepted for publication in Solid State Commu
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