10,689 research outputs found

    Composition dependence of ion transport coefficients in gas mixtures

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    A simple momentum-transfer theory for the composition dependence of ion mobilities and diffusion coefficients in gas mixtures at arbitrary field strengths is corrected, extended, and compared with a similar theory based on momentum and energy transfer, and with results based on direct solution of the Boltzmann equation by Kihara's method. Final equations are recommended for predicting composition dependences, given only results on ion mobilities and diffusion coefficients in the pure component gases

    Electrometer system measures nanoamps at high voltage

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    Floating electrometer eliminates major source of error since any leakage from electrometer case, which is at high voltage, appears only as load on high voltage supply and not as part of current being measured. Commands to and data from floating electrometer are transferred across high voltage interface by means of optical channels

    A Field Evaluation of Selected Beach-Cleaning Techniques

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    A series of experiments was conducted to evaluate selected countermeasures for the cleanup of oil on remote beaches. These experiments formed part of the Baffin Island Oil Spill (BIOS) Project, which was conducted at Cape Hatt, N.W.T., between 1980 and 1983. An isolated lagoon was selected with a series of segregated bays that could be used for discrete experiments with control and countermeasure plots. Intertidal control plots were established in 1980 at an exposed site and at a relatively sheltered location. The oil on the exposed intertidal control plot was removed rapidly by natural processes so that subsequent attention was focused on low wave energy sites. Countermeasure experiments were conducted in 1981 in the intertidal zone at a relatively sheltered site and in 1982 in the intertidal and backshore zones at a very sheltered beach. At each of these two locations, control and countermeasure plots were duplicated using an aged Lagomedio crude oil and a water in aged Lagomedio emulsion. Countermeasures were selected for testing on the basis of existing experimental or practical knowledge and the applicability to remote or arctic beach environments. The selected techniques were incendiary combustion, mechanical mixing, chemical dispersion, solidifying and low-pressure flushing. ...Key words: countermeasures, dispersants, flushing, incendiary devices, mixing, natural cleaning, oil spill, shoreline, solidifying agentMots clés: mesures d’intervention, agents de dispersion, lavage à grande eau, mécanismes incendiaires, brassage, nettoyage naturel, déversement depétrole, littoral, agent solidifian

    Ubiquitin-based probes prepared by total synthesis to profile the activity of deubiquitinating enzymes

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    Epitope-tagged active-site-directed probes are widely used to visualize the activity of deubiquitinases (DUBs) in cell extracts, to investigate the specificity and potency of small-molecule DUB inhibitors, and to isolate and identify DUBs by mass spectrometry. With DUBs arising as novel potential drug targets, probes are required that can be produced in sufficient amounts and to meet the specific needs of a given experiment. The established method for the generation of DUB probes makes use of labor-intensive intein-based methods that have inherent limitations concerning the incorporation of unnatural amino acids and the amount of material that can be obtained. Here, we describe the total chemical synthesis of active-site-directed probes and their application to activity-based profiling and identification of functional DUBs. This synthetic methodology allowed the easy incorporation of desired tags for specific applications, for example, fluorescent reporters, handles for immunoprecipitation or affinity pull-down, and cleavable linkers. Additionally, the synthetic method can be scaled up to provide significant amounts of probe. Fluorescent ubiquitin probes allowed faster, in-gel detection of active DUBs, as compared to (immuno)blotting procedures. A biotinylated probe holding a photocleavable linker enabled the affinity pull-down and subsequent mild, photorelease of DUBs. Also, DUB activity levels were monitored in response to overexpression or knockdown, and to inhibition by small molecules. Furthermore, fluorescent probes revealed differential DUB activity profiles in a panel of lung and prostate cancer cells

    Fate and Persistence of Crude Oil Stranded on a Sheltered Beach

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    Detailed observations, mapping and sampling were conducted following an experimental spill of 15 cu m of crude oil adjacent to the coast at Cape Hatt, Baffin Island, N.W.T. The beach could not retain all of the oil that reached the shoreline, and as a result, one-third of the spill oil was recovered in cleanup activities on the water, approximately one-third was lost to the atmosphere and to the ocean and one-third remained stranded on the intertidal zone. The stranded oil was subject to natural cleaning processes during approximately 6 months of open-water periods from 1981 to 1983. Over this period the surface area of oil cover was reduced by approximately half, whereas estimates indicate that 80% of the oil initially stranded (5.3 cu m) was removed. This natural removal of stranded oil occurred in a very sheltered environment. The reduction of the surface area and of the volume of oil resulted primarily from the physical processes associated with wave activity and ground-water leaching. By 1983 an asphalt pavement had developed in the upper intertidal zone on the beach-face slope. Total hydrocarbon concentrations of samples collected from the asphalt pavement indicated a significant increase in oil-in-sediment values in this zone to concentrations in the order of 2-5%. Oil removed from the beach was transported into the adjacent nearshore bottom sediments, where oil concentrations increased sixfold between 1981 and 1983. Physio-chemical weathering rates were relatively rapid immediately following the release of the oil, as the lower molecular weight (C1 to C10) hydrocarbons evaporated. Subsequent physio-chemical changes were heterogeneous .... The primary conclusion from the investigations undertaken to date is that oil is removed in substantial quantities from the intertidal zone even in such a sheltered, low-energy arctic environment. Similar changes should also be expected from comparable environments in lower latitudes.Key words: oil spill, natural oil weathering, asphalt pavement, beached oilMots clés: déversement de pétrole, dégradation naturelle du pétrole, plaque d’asphalte, pétrole échou&eacute

    Physiological and growth responses to water deficit in the bioenergy crop Miscanthus x giganteus

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    High yielding perennial biomass crops of the species Miscanthus are widely recognized as one of the most promising lignocellulosic feedstocks for the production of bioenergy and bioproducts. Miscanthus is a C(4) grass and thus has relatively high water use efficiency. Cultivated Miscanthus comprises primarily of a single clone, Miscanthus x giganteus, a sterile hybrid between M. sacchariflorus and M. sinensis. M. x giganteus is high yielding and expresses desirable combinations of many traits present in the two parental species types; however, it responds poorly to low water availability. To identify the physiological basis of the response to water stress in M. x giganteus and to identify potential targets for breeding improvements we characterized the physiological responses to water-deficit stress in a pot experiment. The experiment has provided valuable insights into the temporal aspects of drought-induced responses of M. x giganteus. Withholding water resulted in marked changes in plant physiology with growth-associated traits among the first affected, the most rapid response being a decline in the rate of stem elongation. A reduction in photosynthetic performance was among the second set of changes observed; indicated by a decrease in stomatal conductance followed by decreases in chlorophyll fluorescence and chlorophyll content. Measures reflecting the plant water status were among the last affected by the drought treatment. Metabolite analysis indicated that proline was a drought stress marker in M. x giganteus, metabolites in the proline synthesis pathway were more abundant when stomatal conductance decreased and dry weight accumulation ceased. The outcomes of this study in terms of drought-induced physiological changes, accompanied by a proof-of-concept metabolomics investigation, provide a platform for identifying targets for improved drought-tolerance of the Miscanthus bioenergy crop

    Visualização de Dados do Exame Nacional Brasileiro do Ensino Médio: VisDadosEnem

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    Artigo apresentado no I Workshop de Informação, Dados e Tecnologia, realizado entre nos dias 04 e 06 de setembro de 2017, na cidade de Florianópolis (SC), no Auditório do Espaço Físico Integrado (EFI) da Universidade Federal de Santa Catarina (UFSC).Hoje em dia, baseado na quantidade de dados disponíveis surgem situações em que a visualização da informação torna-se fundamental para o entendimento e interpretação dos dados. Dentro deste contexto, este estudo tem como objetivo relacionar e explorar, através de técnicas de visualização, dados abertos educacionais em um contexto multidisciplinar. Para tal, foi desenvolvido uma aplicação Web para visualização de dados do exame nacional Brasileiro do ensino médio (ENEM). Neste estudo utilizou-se os microdados do ENEM, a partir do portal Brasileiro de dados abertos. Como resultado das análises comparativas realizadas sobre os dados, por estados, regiões e tipos de escolas, observou-se quais estados obtiveram as maiores e menores médias do ENEM em relação as médias nacionais. Por exemplo, no estado de Santa Catarina os alunos oriundos de escolas particulares obtiveram 12.70% acima da média nacional para este tipo de escola e a menor média de idade dos alunos inscritos correspondendo a 21,6 anos de idade. A aplicação Web de visualização possibilitou uma análise comparativa sobre o grande conjunto de dados e a exploração de possibilidades de visualização que seriam dificilmente possíveis de realizar por meio de representações tradicionais.Nowadays, based on the amount of available data, there are situations in which the information visualization becomes fundamental for the understanding and interpretation of the data. In this context, the study aims to relate and explore, through visualization techniques, open educational data in a multidisciplinary context. For that, a Web application was developed for data visualization of the Brazilian national high school exam (ENEM). In this study, the ENEM microdata was used, from the Brazilian open data portal. As a result of the comparative analyzes performed on the data, by states, regions and types of schools, it was observed which states obtained the highest and lowest averages of ENEM in relation to national averages. For example, in the state of Santa Catarina, students from private schools obtained 12.70% above the national average for that type of school and the lowest average age of enrolled students corresponding to 21.6 years old. The visualization Web application made possible a comparative analysis on the large dataset and the exploration of visualization possibilities that would be difficult to perform through traditional representations
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