31,647 research outputs found

    Combined Release and Radiation Effects Satellite (CRRES) experiments data collection, analysis, and publication

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    The Combined Release and Radiation Effects Satellite (CRRES) program experiments data collection, analysis, and publication activities are described. These activities were associated with both the satellite chemical release and a planned Puerto Rico sounding rocket campaign. To coordinate these activities, a working group meeting was organized and conducted

    On Atkin and Swinnerton-Dyer Congruence Relations (2)

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    In this paper we give an example of a noncongruence subgroup whose three-dimensional space of cusp forms of weight 3 has the following properties. For each of the four residue classes of odd primes modulo 8 there is a basis whose Fourier coefficients at infinity satisfy a three-term Atkin and Swinnerton-Dyer congruence relation, which is the pp-adic analogue of the three-term recursion satisfied by the coefficients of classical Hecke eigen forms. We also show that there is an automorphic LL-function over Q\mathbb Q whose local factors agree with those of the ll-adic Scholl representations attached to the space of noncongruence cusp forms.Comment: Last version, to appear on Math Annale

    Accuracy Assessment of the 2006 National Land Cover Database Percent Impervious Dataset

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    An impervious surface is any surface that prevents water from infiltrating the ground. As impervious surface area increases within watersheds, stream networks and water quality are negatively impacted. The Multi-Resolution Land Characteristic Consortium developed a percent impervious dataset using Landsat imagery as part of the 2006 National Land Cover Database. This percent impervious dataset estimates imperviousness for each 30-meter cell in the land cover database. The percent impervious dataset permits study of impervious surfaces, can be used to identify impacted or critical areas, and allows for development of impact mitigation plans; however, the accuracy of this dataset is unknown. To determine the accuracy of the 2006 percent impervious dataset, reference data were digitized from one-foot digital aerial imagery for three study areas in Arkansas, USA. Digitized reference data were compared to percent impervious dataset estimates of imperviousness at multiple 900m2 , 8,100m2 , and 22,500m2 sample grids to determine if accuracy varied by ground area. Analyses showed percent impervious estimates and digitized reference data differ modestly; however, as ground area increases, percent impervious estimates and reference data match more closely. These findings suggest that the percent impervious dataset is useful for planning purposes for ground areas of at least 2.25ha

    Lattice-Driven Magnetoresistivity and Metal-Insulator Transition in Single-Layered Iridates

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    Sr2IrO4 exhibits a novel insulating state driven by spin-orbit interactions. We report two novel phenomena, namely a large magnetoresistivity in Sr2IrO4 that is extremely sensitive to the orientation of magnetic field but exhibits no apparent correlation with the magnetization, and a robust metallic state that is induced by dilute electron (La3+) or hole (K+) doping for Sr2+ ions in Sr2IrO4. Our structural, transport and magnetic data reveal that a strong spin-orbit interaction alters the balance between the competing energies so profoundly that (1) the spin degree of freedom alone is no longer a dominant force; (2) underlying transport properties delicately hinge on the Ir-O-Ir bond angle via a strong magnetoelastic coupling; and (3) a highly insulating state in Sr2IrO4 is proximate to a metallic state, and the transition is governed by lattice distortions. This work suggests that a novel class of lattice-driven electronic materials can be developed for applications.Comment: 4 figure
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