44,349 research outputs found

    A mid-Archaean ophiolite complex, Barberton Mountain land

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    New field observations and structurally restored geologic sections through the southern part of 3.5-3.6 Ga Barberton greenstone belt show that its mafic to ultramafic rocks form a pseudostratigraphy comparable to that of Phanerozoic ophiolites; this ancient ophiolite is referred to as the Jamestown ophiolite complex. It consists of an intrusive-extrusive mafic-ultramafic section, underlain by a high-temperature tectono-metamorphic residual peridotitic base, and is capped by a chert-shale sequence which it locally intrudes. Geochemical data support an ophiolitic comparison. Fraction of high temperature melting PGE's 2500 C in the residual rocks suggest a lower mantle origin for the precursors of this crust. An oceanic rather than arc-related crustal section can be inferred from the absence of contemporaneous andesites. The entire simatic section has also been chemically altered during its formation by hyrothermal interaction with the Archean hydrosphere. The most primitive parent liquids, from which the extrusive sequence evolved, may have been picritic in character. Rocks with a komatiitic chemistry may have been derived during crystal accumulation from picrite-crystal mushes (predominantly olivine-clinopyroxene) and/or by metasomatism during one or more subsequent episodes of hydration-dehydration. The Jamestown ophiolite complex provides the oldest record with evidence for the formation of oceanic lithosphere at constructive tectonic boundaries

    Elementary review of electron microprobe techniques and correction requirements

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    Report contains requirements for correction of instrumented data on the chemical composition of a specimen, obtained by electron microprobe analysis. A condensed review of electron microprobe techniques is presented, including background material for obtaining X ray intensity data corrections and absorption, atomic number, and fluorescence corrections

    Public Lending Right: The American Author's Viewpoint

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    Annie Proulx’s Imaginative Leap: Constructing Gay Masculinity in “Brokeback Mountain”

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    Non-heterosexual men have long existed on the social and cultural margins. Gay and bisexual male characters in literature, too, have done so for many generations. This essay explores the construction of gay masculinity in the short story “Brokeback Mountain” in relation to the “imaginative leap” that its author, Annie Proulx, undertook in order to conceptualize and represent this noteworthy form of marginalized otherness. It demonstrates that, despite the story’s various refreshing elements, “Brokeback Mountain” ultimately relies far too extensively on the logic of melodrama when telling the tale of Ennis del Mar and Jack Twist, who fall in love in 1963 and continue their sexual relationship over the course of two decades. As a result, this story ends up positioning its two queer protagonists as enemies of the patriarchal social order and the larger society within which it so comfortably exists, implicitly perpetuating both heterosexism and homophobia as it does its cultural work

    Demonstrated results of welded and soldered interconnections

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    Solar cell modules with welded and soldered interconnections were constructed using a flexible substrate material. These modules were thermally cycled between approx. 80 deg C at rates 100 cycles/day to demonstrate survivability under simulated low Earth orbit (LEO) temperature conditions. The modules, cycled in an inert atmosphere, show durability for 36,000 cycles

    Parasitoids of \u3ci\u3eChionaspis Pinifoliae\u3c/i\u3e (Homoptera: Diaspididae) in Iowa

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    Three parasitoids (Hymenoptera: Encyrtidae: Aphelininae), Aphytis diaspidis, Coccobius varicornis, and Marietta pulchella, were recovered from field collections of the pine needle scale, Chionaspis pinifoliae, on Pinus sylvestris in central Iowa. Parasitoid mean time (± SEM) to emergence from overwintered scale mummies occurred at 46.6 (4.6) and 23.9 (1.3) days for C. varicornis and M. pulchella, respectively, using a 16L:8D photoperiod and a corresponding temperature regime of 22°C and 18°C. Growing-season parasitism level on field-collected female C. pinifoliae was 15%; parasitoid community composition was 86% A. diaspidis, 12% C. varicornis, and 2% M. pulchella

    Pupal and Adult Parameters as Potential Indicators of Cottonwood Leaf Beetle (Coleoptera: Chrysomelidae) Fecundity and Longevity

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    Cottonwood leaf beetle, Chrysomela scripta, pupae from a laboratory colony were weighed and monitored through adult emergence, oviposition, and mortality to determine if correlations existed between various pupal or adult parameters and fecundity or longevity. Forty-three female cottonwood leaf beetles were monitored. Pupal weight was not a good indicator of fecundity, total oviposition events, number of eggs/beetle/day, or adult longevity. In addition, adult weight showed very low correlation with fecundity, adult longevity, total oviposition events, or number of eggs/beetle/day. However, adult weight was a marginal indicator of the number of eggs/beetle/day, and correlated well with adult body length. Adult longevity could be used to predict fecundity
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