567 research outputs found

    RECENT PROGRESSES ON GENUS ONE EXTENSIONS OF MIXED TATE MOTIVES OVER Z (Various aspects of multiple zeta values)

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    In this survey article, we give an overview of recent progress of construction of genus one extension of the category of mixed Tate motives over ℤ by Brown [6] and Hain-Matsumoto [18]

    Development of an Analytical Method for Nitric Oxide Radical Determination in Natural Waters

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    The measurement of photochemically generated nitric oxide radicals (NO) in natural waters has long been an arduous task because of a lack of simple analytical techniques, even though the environmental significance of this radical is paramount. We have developed a simple analytical method for the determination of photochemically generated NO in natural waters using 4,5-diaminofluorescein (DAF-2) as a probe compound. This method is based on the reaction of photoformed NO with DAF-2 in air-saturated solution to produce a highly fluorescent triazolofluorescein (DAF-2T) product. DAF-2T was determined by using reversed-phase HPLC with fluorescence detection, with excitation and emission wavelengths of 495 and 515 nm, respectively. Under optimum conditions, the calibration curve exhibited linearity in the range of 0.025−10 nM DAF-2T. The coefficients of variance for the measurements of the signal intensities of DAF-2T (from the photolysis of 0.5 μM and 5 μM NO2− with DAF-2) were less than 5% and 3%, respectively. For a total irradiation time of 30 min, the detection limit of the photoformation rate of NO was 1.65 × 10−13 M s−1, defined as 3σ of the lowest measured DAF-2T concentration (0.025 nM). The proposed method is relatively unaffected by potential interferents in seawater. The method was employed to determine the photoformation rate of NO in the Seto Inland Sea and the Kurose River in Hiroshima Prefecture, Japan. The measured NO photoformation rates in seawater and river water samples ranged from (5.3−32) × 10−12 M s−1 and (9.4−300) × 10−12 M s−1, respectively

    Liberación o dependencia: documento de Conciencia Nacional-FURN (1973)

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    El presente texto reproduce el documento “Desarrollismo y dependencia”, publicado en septiembre de 1973 por “Conciencia Nacional”, la Agrupación de Económicas de la Federación Universitaria de la Revolución Nacional (FURN). En la introducción se analiza el contexto político y universitario entre 1968 y 1973, que dio lugar al nacimiento del documento. Mientras que a continuación se transcribe el documento original, que buscaba analizar las características que adoptó la dependencia económica desde 1955 y las estrategias de crecimiento que contribuyeron a perpetuarla, para concluir proponiendo como salida liberadora el socialismo nacional.Facultad de Ciencias Económica

    Photochemical Production and Consumption Mechanisms of Nitric Oxide in Seawater

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    Nitric oxide (NO•) is an active odd-nitrogen species that plays a critical role in determining the levels of ozone (O3) and other nitrogen species in the troposphere. Here, we provide experimental evidence for photochemical formation of NO• in seawater. Photoproduction rates and overall scavenging rate constants were measured by irradiation of surface seawater samples collected from the Seto Inland Sea, Japan. Photoproduction rates of NO• ranged from 8.7 × 10−12 M s−1 to 38.8 × 10−12 M s−1 and scavenging rate constants were 0.05−0.33 s−1. The steady state concentrations of NO• in seawater, which were calculated from the photoproduction rates and scavenging rate constants were in the range 2.4−32 × 10−11 M. Estimation from the scavenging rate constant showed that the NO• lifetime in seawater was a few seconds. Our results indicate that nitrite photolysis plays a crucial role in the formation of NO•, even though we cannot exclude minor contributions from other sources. Analysis of filtered and unfiltered seawater samples showed no significant difference in NO• photoformation rates, which suggests a negligible contribution of NO• produced by photobiological processes. Using an estimated value of the Henry’s law constant (kH ≈ 0.0019 M atm−1), a supersaturation of surface seawater of 2 to 3 orders of magnitude was estimated. On the basis of the average values of the surface seawater concentration and the atmospheric NO• concentration, a sea-to-air NO• flux was estimated

    On a non-abelian generalization of the Bloch–Kato exponential map

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    The present paper establishes a non-abelian generalization of the Bloch–Kato exponential map. Then, we relate p-adic polylogarithms introduced by Coleman to `-adic polylogarithms introduced by Wojtkowiak. This formula is another analog of the Coleman–Ihara formula obtained by Nakamura, Wojtkowiak, and the author
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