19,183 research outputs found

    \u3ci\u3eAgonopterix Alstroemeriana\u3c/i\u3e (Oecophoridae) and Other Lepidopteran Associates of Poison Hemlock \u3ci\u3e(Conium Maculatum)\u3c/i\u3e in East Central Illinois

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    Poison hemlock (Conium maculatum) (Apiaceae), a noxious Eurasian weed extensively naturalized throughout North America, is characteristically attacked by few insects. Over the past two decades, an introduced oecophorid caterpillar, Agonopterix alstroemeriana, has been reported infesting poison hemlock, its sole host in its area of indigeneity, in parts of the northeastern and western United States. We report for the first time evidence of established midwestern populations of this species. We also report poison hemlock as a host plant for the polyphagous lepidopterans Eupithecia miserulata, Trichoplusia ni, and Spilosoma virginica

    Spin-dependent electron-hole capture kinetics in conjugated polymers

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    The recombination of electron-hole pairs injected in extended conjugated systems is modeled as a multi-pathway vibron-driven relaxation in monoexcited state-space. The computed triplet-to-singlet ratio of exciton formation times r=τT/τSr = \tau_T/\tau_S increases from 0.9 for a model dimer to 2.5 for a 32-unit chain, in excellent agreement with experiments. Therewith we rationalize recombination efficiency in terms of spin-dependent interstate vibronic coupling and spin- and conjugation-length-dependent exciton binding energies.Our model calculations for various length polymers indicate that the ratio of the singlet to triplet formation ratios, r=σS/σTr = \sigma_S/\sigma_T, is inversely related to the ratio of the singlet and triplet binding energies, ϵSb/ϵTb\epsilon^b_S/\epsilon^b_T

    Ammonia adsorption and decomposition on a tungsten /211/ surface

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    Ammonia adsorption and decomposition on tungsten 211 surface studied by mass spectrometry, electron diffraction, and changes in work functio

    First steps in the oxidation of a /110/ nickel surface

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    Initial steps in oxidation of nickel surface studied using low energy back-reflection electron diffractio

    Epidemic threshold in structured scale-free networks

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    We analyze the spreading of viruses in scale-free networks with high clustering and degree correlations, as found in the Internet graph. For the Suscetible-Infected-Susceptible model of epidemics the prevalence undergoes a phase transition at a finite threshold of the transmission probability. Comparing with the absence of a finite threshold in networks with purely random wiring, our result suggests that high clustering and degree correlations protect scale-free networks against the spreading of viruses. We introduce and verify a quantitative description of the epidemic threshold based on the connectivity of the neighborhoods of the hubs.Comment: 4 pages, 4 figure

    Secondary literacy across the curriculum: Challenges and possibilities

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    This paper discusses the challenges and possibilities attendant upon successfully implementing literacy across the curriculum initiatives – or ‘school language policies’ as they have come to be known - particularly at the secondary or high school level. It provides a theoretical background to these issues, exploring previous academic discussions of school language policies, and highlights key areas of concern as well as opportunity with respect to school implementation of such policies. As such, it provides a necessary conceptual background to the subsequent papers in this special issue, which focus upon the Secondary Schools’ Literacy Initiative (SSLI) – a New Zealand funded programme that aims to establish cross-curricular language and literacy policies in secondary schools

    Three-dimensional simulations of laser-plasma interactions at ultrahigh intensities

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    Three-dimensional (3D) particle-in-cell (PIC) simulations are used to investigate the interaction of ultrahigh intensity lasers (>1020> 10^{20} W/cm2^{-2}) with matter at overcritical densities. Intense laser pulses are shown to penetrate up to relativistic critical density levels and to be strongly self-focused during this process. The heat flux of the accelerated electrons is observed to have an annular structure when the laser is tightly focused, showing that a large fraction of fast electrons is accelerated at an angle. These results shed light into the multi-dimensional effects present in laser-plasma interactions of relevance to fast ignition of fusion targets and laser-driven ion acceleration in plasmas.Comment: 2 pages, 1 figur

    ENVIRONMENTAL ETHICAL DECISION MAKING IN THE U.S. METAL-FINISHING INDUSTRY

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    We investigated the individual and contextual influences shaping the environmental ethical decision intentions of a sample of managers in the U.S. metal-finishing industry in this study. Ajzen\u27s (1991) theory of planned behavior and Jones\u27s (1991) moral intensity construct grounded our theoretical framework. Findings revealed that the magnitude of consequences, a dimension of moral intensity, moderated the relation- ships between each of five antecedents-attitudes, subjective norms, and three perceived behavioral control factors (self-efficacy, financial cost, and ethical climate)- and managers\u27 environmental ethical decision intentions. We then developed implications for theory and practice in environmental ethical decision making
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