260 research outputs found

    Anodic dissolution of metals in oxide-free cryolite melts

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    The anodic behavior of metals in molten cryolite-alumina melts has been investigated mostly for use as inert anodes for the Hall-Héroult process. In the present work, gold, platinum, palladium, copper, tungsten, nickel, cobalt and iron metal electrodes were anodically polarized in an oxide-free cryolite melt (11%wt. excess AlF3 ; 5%wt. CaF2) at 1273 K. The aim of the experiments was to characterize the oxidation reactions of the metals occurring without the effect of oxygen-containing dissolved species. The anodic dissolution of each metal was demonstrated, and electrochemical reactions were assigned using reversible potential calculation. The relative stability of metals as well as the possibility of generating pure fluorine is discussed

    The Marshes of Back Bay, Virginia

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    An inventory was undertaken to determine the type and extent of the emergent tidal wetlands in Back Bay, which, historically, has ranged from a lunar tidal brackish estuary to a wind tidal freshwater system. The inventory was conducted primarily by boat with visual observations made for each marsh. The configuration and areal extent of each marsh was determined from USGS topographic maps and confirmed with aerial photography where necessary. Approximately 9925 acres of wetlands as defined by the Commonwealth of Virginia were identified within the watershed. These wetlands supported a very diverse flora consisting of over 109 species. The five dominant species accounted for almost 75% of the wetland acreage. They included: cattails, Typha spp., (4004 acres), needlerush, ]uncus roemerianus, (2371 acres), big cordgrass, Spartina cynosuroides, (605 acres), saltmeadow hay, Sp.artina patens, (449 acres) and switchgrass Panicum virgatum, (427 acres). The remainder of the species represented a diverse mixture of brackish plants with a significant component of freshwater species. The emergent tidal wetlands are dominated by plants typically indicative of brackish conditions even though the system now tends toward freshwater conditions under normal circumstances. These brackish species are probably relicts from when Back Bay was directly influenced by the salinity and tides afforded by inlets to the ocean. The brackish communities because of their continued dominance appear to be more adaptable to the periods of freshwater than the freshwater species are to periods of brackish conditions. These historical oscillations between brackish and fresh conditions are probably responsible for much of the plant diversity found. These plant communities are not static either, as evidenced by changes in the coverage of common reed, Phragmites australis, which has increased substantially between this inventory done in 1977 and recent (1990) observations

    The Coupled Electronic-Ionic Monte Carlo Simulation Method

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    Quantum Monte Carlo (QMC) methods such as Variational Monte Carlo, Diffusion Monte Carlo or Path Integral Monte Carlo are the most accurate and general methods for computing total electronic energies. We will review methods we have developed to perform QMC for the electrons coupled to a classical Monte Carlo simulation of the ions. In this method, one estimates the Born-Oppenheimer energy E(Z) where Z represents the ionic degrees of freedom. That estimate of the energy is used in a Metropolis simulation of the ionic degrees of freedom. Important aspects of this method are how to deal with the noise, which QMC method and which trial function to use, how to deal with generalized boundary conditions on the wave function so as to reduce the finite size effects. We discuss some advantages of the CEIMC method concerning how the quantum effects of the ionic degrees of freedom can be included and how the boundary conditions can be integrated over. Using these methods, we have performed simulations of liquid H2 and metallic H on a parallel computer.Comment: 27 pages, 10 figure

    Politische Dimensionen von Militärübungen und Manövern – ein Projektbericht

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    Die virtuellen Kriege und Operationen, die in Militärübungen gespielt und geprobt werden, können entweder der Abschreckung dienen oder aber Angriffe vorbereiten bzw. zur Maskierung tatsächlicher Angriffe dienen. Für Beobachter ist es vielfach nicht offensichtlich, um welche Art von Militärübung es sich handelt. Die Ergebnisse eines vierjährigen internationalen Projektes zu politischen Dimensionen von Militärübungen richten das Schlaglicht insbesondere auf Missverständnisse und deren ungewollte politische Auswirkungen, die im Extremfall unbeabsichtigt zum Krieg führen können

    The accuracy of MRI in the detection of Lumbar Disc Containment

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    <p>Abstract</p> <p>Background</p> <p>MRI has proven to be an extremely valuable tool in the assessment of normal and pathological spinal anatomy. Accordingly, it is commonly used to assess containment of discal material by the outer fibers of the anulus fibrosus and posterior longitudinal ligaments. Determination of such containment is important to determine candidacy for intradiscal techniques and has prognostic significance. The accuracy of MRI in detecting containment has been insufficiently documented.</p> <p>Methods</p> <p>The MRI's of fifty consecutive patients undergoing open lumbar microdiscectomy were prospectively evaluated for disc containment by a neuroradiologist and senior spinal surgeon using criteria available in the literature and the classification of Macnab/McCulloch. An independent surgeon then performed the surgery and documented the actual containment status using the same methods. Statistical evaluation of accuracy was undertaken.</p> <p>Results</p> <p>MRI was found to be 72% sensitive, 68% specific, and 70% accurate in detecting containment status of lumbar herniated discs.</p> <p>Conclusion</p> <p>MRI may be inaccurate in assessing containment status of lumbar disc herniations in 30% of cases. Given the importance of containment for patient selection for indirect discectomy techniques and intradiscal therapies, coupled with prognostic significance; other methods to assess containment should be employed to assess containment when such alternative interventions are being considered.</p

    New and Interesting Fungi. 7.

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    Two new genera, 17 new species, two epitypes, and six interesting new host and / or geographical records are introduced in this study. New genera include: Cadophorella (based on Cadophorella faginea) and Neosatchmopsis (based on Neosatchmopsis ogrovei). New species include: Alternaria halotolerans (from hypersaline sea water, Qatar), Amylostereum stillwellii (from mycangia of Sirex areolatus, USA), Angiopsora anthurii (on leaves of Anthurium andraeanum, Brazil), Anthracocystis zeae-maydis (from pre-stored Zea mays, South Africa), Bisifusarium solicola (from soil, South Africa), Cadophorella faginea (from dead capsule of Fagus sylvatica, Germany), Devriesia mallochii (from house dust, Canada), Fusarium kirstenboschense (from soil, South Africa), Macroconia podocarpi (on ascomata of ascomycete on twigs of Podocarpus falcatus, South Africa), Neosatchmopsis ogrovei (on Eucalyptus leaf litter, Spain), Ophiocordyceps kuchinaraiensis (on Coleoptera larva, Thailand), Penicillium cederbergense (from soil, South Africa), Penicillium pascuigraminis (from pasture mulch, South Africa), Penicillium viridipigmentum (from soil, South Africa), Pleurotheciella acericola (on stem, bark of living tree of Acer sp., Germany), Protocreopsis physciae (on Physcia caesia, Netherlands), and Talaromyces podocarpi (from soil, South Africa)

    Better Palliative Care for people with a Dementia: Summary of InterdisciplinaryWorkshop Highlighting Current Gaps and Recommendations for Future Research

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    Background: Dementia is the most common neurological disorder worldwide and is a life-limiting condition, but very often is not recognised as such. People with dementia, and their carers, have been shown to have palliative care needs equal in extent to those of cancer patients. However, many people with advanced dementia are not routinely being assessed to determine their palliative care needs, and it is not clear why this is so. Main body: An interdisciplinary workshop on "Palliative Care in Neurodegeneration, with a focus on Dementia", was held in Cork, Ireland, in May 2016. The key aim of this workshop was to discuss the evidence base for palliative care for people with dementia, to identify 'gaps' for clinical research, and to make recommendations for interdisciplinary research practice. To lead the discussion throughout the day a multidisciplinary panel of expert speakers were brought together, including both researchers and clinicians from across Ireland and the UK. Targeted invitations were sent to attendees ensuring all key stakeholders were present to contribute to discussions. In total, 49 experts representing 17 different academic and practice settings, attended. Key topics for discussion were pre-selected based on previously identified research priorities (e.g. James Lind Alliance) and stakeholder input. Key discussion topics included: i. Advance Care Planning for people with Dementia; ii. Personhood in End-of-life Dementia care; iii. Topics in the care of advanced dementia at home. These topics were used as a starting point, and the ethos of the workshop was that the attendees could stimulate discussion and debate in any relevant area, not just the key topics, summarised under iv. Other priorities. Conclusions: The care experienced by people with dementia and their families has the potential to be improved; palliative care frameworks may have much to offer in this endeavour. However, a solid evidence base is required to translate palliative care into practice in the context of dementia. This paper presents suggested research priorities as a starting point to build this evidence base. An interdisciplinary approach to research and priority setting is essential to develop actionable knowledge in this area

    Transcriptomic Analyses Reveal Novel Genes with Sexually Dimorphic Expression in the Zebrafish Gonad and Brain

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    Background Our knowledge on zebrafish reproduction is very limited. We generated a gonad-derived cDNA microarray from zebrafish and used it to analyze large-scale gene expression profiles in adult gonads and other organs. Methodology/Principal Findings We have identified 116638 gonad-derived zebrafish expressed sequence tags (ESTs), 21% of which were isolated in our lab. Following in silico normalization, we constructed a gonad-derived microarray comprising 6370 unique, full-length cDNAs from differentiating and adult gonads. Labeled targets from adult gonad, brain, kidney and ‘rest-of-body’ from both sexes were hybridized onto the microarray. Our analyses revealed 1366, 881 and 656 differentially expressed transcripts (34.7% novel) that showed highest expression in ovary, testis and both gonads respectively. Hierarchical clustering showed correlation of the two gonadal transcriptomes and their similarities to those of the brains. In addition, we have identified 276 genes showing sexually dimorphic expression both between the brains and between the gonads. By in situ hybridization, we showed that the gonadal transcripts with the strongest array signal intensities were germline-expressed. We found that five members of the GTP-binding septin gene family, from which only one member (septin 4) has previously been implicated in reproduction in mice, were all strongly expressed in the gonads. Conclusions/Significance We have generated a gonad-derived zebrafish cDNA microarray and demonstrated its usefulness in identifying genes with sexually dimorphic co-expression in both the gonads and the brains. We have also provided the first evidence of large-scale differential gene expression between female and male brains of a teleost. Our microarray would be useful for studying gonad development, differentiation and function not only in zebrafish but also in related teleosts via cross-species hybridizations. Since several genes have been shown to play similar roles in gonadogenesis in zebrafish and other vertebrates, our array may even provide information on genetic disorders affecting gonadal phenotypes and fertility in mammals
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