5,870 research outputs found

    High temperature–high pressure thermal conductivities of ethylene and propane

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    Thermal conductivities λ of ethylene and propane were measured in the temperature and pressure ranges 400–750 K and 0.1–2.65 MPa (ethylene) and 400–725 K and 0.1 to 0.6 MPa (propane). The data were correlated by expressions of the form λ=λ0(T) ×λp(P), with λ0 being a second order polynomial in temperature and λp a third (ethylene) or a fourth (propane) order polynomial in pressure. The results obtained were compared with previous thermal conductivity measurements.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71313/2/JCPSA6-70-8-3948-1.pd

    Vibrational relaxation times in some hydrocarbons in the range 300–900°K

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    Vibrational relaxation times were determined in methane, ethylene, acetylene, and cyclopropane in the temperature range 300–900°K. The experiments were performed by measuring the absorption and dispersion of ultrasonic waves passing through the vapor. For all four vapors, the vibrational relaxation time Ï„Îœ (sec) was found to vary with temperature T(°K) according to the relationship log10(Ï„Îœ P) = aT−1∕3 − b, where P is the pressure (atm) and a and b are constants. The results of the present measurements were also found to be in good agreement with existing data.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71108/2/JCPSA6-59-12-6556-1.pd

    Quantum affine Cartan matrices, Poincare series of binary polyhedral groups, and reflection representations

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    We first review some invariant theoretic results about the finite subgroups of SU(2) in a quick algebraic way by using the McKay correspondence and quantum affine Cartan matrices. By the way it turns out that some parameters (a,b,h;p,q,r) that one usually associates with such a group and hence with a simply-laced Coxeter-Dynkin diagram have a meaningful definition for the non-simply-laced diagrams, too, and as a byproduct we extend Saito's formula for the determinant of the Cartan matrix to all cases. Returning to invariant theory we show that for each irreducible representation i of a binary tetrahedral, octahedral, or icosahedral group one can find a homomorphism into a finite complex reflection group whose defining reflection representation restricts to i.Comment: 19 page

    Moisture Absorption of Graphite-Epoxy Composites Immersed in Liquids and in Humid Air

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    Moisture absorption of graphite-epoxy composites immersed in liquids and in himid air were investigated. The moisture content as a function of time and temperature was measured for three materials: Fiberite T300/1034, Hercules AS/3501-5 and Narmco T300/5208. Tests were per formed a) with the materials immersed in No. 2 diesel fuel, in jet A fuel, in aviation oil, in saturated salt water, and in distilled water (in the range of 300 to 322 K) and b)with the materials exposed to humid air (in the range 322 to 366 K). The results obtained were compared to available composite and neat resin data.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68153/2/10.1177_002199837901300205.pd

    Conditions for Factorizable Output From a Beam splitter

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    A beam splitter is one of the most important devices in an optics laboratory because of its handiness and versatility; equivalent devices are found in various quantum systems to couple two subsystems or to interfere them. While it is normal that two independent input fields are superposed at the beam splitter to give correlated outputs, identical Gaussian states interfere there to produce totally independent output fields. We prove that Gaussian states with same the variance are the only states which bring about factorizable output fields.Comment: 6 pages, published in PR

    The essential Mcm7 protein PROLIFERA is localized to the nucleus of dividing cells during the G(1) phase and is required maternally for early Arabidopsis development

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    PROLIFERA (PRL) encodes a homologue of the DNA replication licensing factor Mcm7, a highly conserved protein found in all eukaryotes. Insertions in the PROLIFERA gene are lethal, resulting in decreased transmission through the female gametophyte, and homozygous embryonic lethality. We show here that PROLIFERA is specifically expressed in populations of dividing cells in sporophytic tissues of the plant body, such as the palisade layer of the leaf and founder cells of initiating flower primordia, Gene fusions with the green fluorescent protein (GFP) reveal that the PROLIFERA protein accumulates during the G(1) phase of the cell cycle, and is transiently localized to the nucleus. During mitosis, the fusion protein rapidly disappears, returning to daughter nuclei during G(1), PROLIFERA::GUS fusions are strongly expressed in the central cell nucleus of mature megagametophytes, which have a variety of arrest points reflecting a leaky lethality. Expression is also observed in the endosperm of mutant prl embryo sacs that arrest following fertilization. Crosses with wild-type pollen result in occasional embryonic lethals that also stain for GUS activity, In contrast, embryos resulting from crosses of wild-type carpels with PRL::GUS pollen do not stain and are phenotypically normal. In situ hybridization of GUS fusion RNA indicates transcription is equivalent from maternally and paternally derived alleles, so that accumulation of maternally derived gametophytic protein is likely to be responsible for the 'maternal' effect

    The poverty of journal publishing

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    The article opens with a critical analysis of the dominant business model of for-profit, academic publishing, arguing that the extraordinarily high profits of the big publishers are dependent upon a double appropriation that exploits both academic labour and universities’ financial resources. Against this model, we outline four possible responses: the further development of open access repositories, a fair trade model of publishing regulation, a renaissance of the university presses, and, finally, a move away from private, for-profit publishing companies toward autonomous journal publishing by editorial boards and academic associations. </jats:p

    Effects of Thermal Spiking on Graphite-Epoxy Composites

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    Tests were performed evaluating the effects of thermal spikes on the moisture absorption characteristics, the ultimate tensile strength, and the buckling modulus of Thornel 300/Fiberite 1034 composites. Measurements were made on unidirectional and π/4 laminates, using different types of thermal spikes. A survey was also made of the existing data. This survey, together with the present data indicate how thermal spikes affect the mois ture absorption and the mechanical properties of different graphite-epoxy composites.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66923/2/10.1177_002199837901300102.pd
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