5,082 research outputs found

    Testing of brazed and welded connections of stainless-steel tubing

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    Test procedures and results are given for three types of semipermanent sleeve-type connections for stainless-steel tubing. Subject to the limited resistances to corrosion and vibration, all three types are found to be suitable for extremes in reliability and environment, if given close control during manufacture

    Synthetic Quantum Systems

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    So far proposed quantum computers use fragile and environmentally sensitive natural quantum systems. Here we explore the new notion that synthetic quantum systems suitable for quantum computation may be fabricated from smart nanostructures using topological excitations of a stochastic neural-type network that can mimic natural quantum systems. These developments are a technological application of process physics which is an information theory of reality in which space and quantum phenomena are emergent, and so indicates the deep origins of quantum phenomena. Analogous complex stochastic dynamical systems have recently been proposed within neurobiology to deal with the emergent complexity of biosystems, particularly the biodynamics of higher brain function. The reasons for analogous discoveries in fundamental physics and neurobiology are discussed.Comment: 16 pages, Latex, 1 eps figure fil

    Cutting Strategies as Control Measures of the Mountain Pine Beetle in Lodgepole Pine in Colorado

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    Efforts to suppress mountain pine beetle (Dendroctonus ponderosae Hopkins) epidemics in Colorado have been carried out since the early 1900s using various methods of treating or removing beetle populations. These methods have slowed the rate of annual tree losses, but have done little to reduce total tree mortality over the course of an infestation, or to reduce the susceptibility of the stands to additional beetle attack. Based on recent research findings that demonstrated the importance of lodgepole pine (Pinus contorta Douglas var. latifolia Englemann) phloem thickness and diameter in mountain pine beetle epidemics, stands in the Middle Park area of Colorado were cut using strategies to reduce stand susceptibility to beetle attack. partial cutting and clearcutting, combined with the logging of infested trees, were used to reduce the inventory of larger-diameter trees. Other factors considered were dwarf mistletoe, comandra rust and visual management concerns. Losses in partial-cut areas have been reduced to 1 to 2 percent of the residual trees, whereas in unmanaged stands 39 percent of the trees have been lost

    Investigation of brazed and welded connections

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    Brazed and welded tube connections tested for space vehicle us

    Haemophilia

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    Although the nature of haemophilia has been understood for thousands of years, knowledge of its molecular genetics is recent. These X-linked bleeding disorders have diverse underlying DNA defects and, in 1992, DNA inversion within the X chromosome was found to explain half of the most serious cases of haemophilia A. The life-span and quality of-life for patients with haemophilia had improved steadily throughout the early 1980s but the principal cause of death remained intracranial haemorrhage until the epidemic of HIV infection due to contaminated factor concentrates. Infection with hepatitis C virus is almost universal for patients treated with clotting factors before 1985. No curative treatment is available for hepatitis C at present. Knowledge of the transmission of viruses in concentrates has led to important developments in processing techniques to eliminate them. Recombinant technology has produced factor VIII and, more recently, factor IX concentrate which is likely to be very safe. Development of inhibitors to factor concentrates (especially factor VIII) remains one of the most serious complications of haemophilia. The variety of treatments available testifies to the lack of a single universally efficacious one. The use of prophylactic treatment has been conclusively demonstrated to result in a preservation of joint function in severely affected patients who might otherwise develop significant joint problems. The many facets of the care of patients with severe haemophilia, ranging from dental care to genetic counselling, can be advantageously co-ordinated in a haemophilia comprehensive care centre

    Molecular Electroporation and the Transduction of Oligoarginines

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    Certain short polycations, such as TAT and polyarginine, rapidly pass through the plasma membranes of mammalian cells by an unknown mechanism called transduction as well as by endocytosis and macropinocytosis. These cell-penetrating peptides (CPPs) promise to be medically useful when fused to biologically active peptides. I offer a simple model in which one or more CPPs and the phosphatidylserines of the inner leaflet form a kind of capacitor with a voltage in excess of 180 mV, high enough to create a molecular electropore. The model is consistent with an empirical upper limit on the cargo peptide of 40--60 amino acids and with experimental data on how the transduction of a polyarginine-fluorophore into mouse C2C12 myoblasts depends on the number of arginines in the CPP and on the CPP concentration. The model makes three testable predictions.Comment: 15 pages, 5 figure

    Timelike self-similar spherically symmetric perfect-fluid models

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    Einstein's field equations for timelike self-similar spherically symmetric perfect-fluid models are investigated. The field equations are rewritten as a first-order system of autonomous differential equations. Dimensionless variables are chosen in such a way that the number of equations in the coupled system is reduced as far as possible and so that the reduced phase space becomes compact and regular. The system is subsequently analysed qualitatively using the theory of dynamical systems.Comment: 23 pages, 6 eps-figure

    Mineralogy of Great Salt Lake: An Analogue for Martian Evaporites

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    Gypsum (CaSO4 · 2H2O) and mirabilite (Na2SO4 · 10H2O) are common precipitates at the Great Salt Lake (GSL). NASA’s Mars Exploration Rover, Opportunity, found veins of gypsum deposited by water in 2011 and gypsum has been detected on Mars as early as 2005 by the ESA’s Mars Express Orbiter. On Earth, gypsum is formed in hypersaline environments, in minerals left behind when water evaporates, trapping microorganisms in fluid inclusions. Likewise, GSL mirabilite develops when mineral-rich groundwater meets cold winter air to create crystalline structures. While there is no physical evidence of mirabilite on Mars, HiRISE Image data show white mounds that some experts hypothesize are related to saline ground waters. Gypsum obtained from Great Salt Lake was used to develop a method to extract halophilic archaea and culture it in the lab. The method obtained could be used to isolate potential microorganisms present in gypsum samples from Mars. Mirabilite is currently under investigation for its ability to enrich halophilic life

    On the Analytic Structure of the Quark Self-Energy in Nambu-Jona- Lasinio Models

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    The self-energy of quarks is investigated for various models which are inspired by the Nambu--Jona-Lasinio (NJL) model. Including, beyond the Hartree-Fock approximation, terms up to second-order in the quark interaction, the real and imaginary parts of scalar and vector components of the self-energy are discussed. The second-order contributions depend on the energy and momentum of the quark under consideration. This leads to solutions of the Dirac equation which are significantly different from those of a free quark or a quark with constant effective mass, as obtained in the Hartree-Fock approximation.Comment: 15 pages LaTeX, 6 figures can be obtained from author
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