755 research outputs found

    Localization of the cohomology of a finite galois group in a dedekind domain

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    LeI us take a Dedekind domain A with field of fractions K. L a finite Galois extensión of K with Galois group G and B the integral closure of A in L. then B is a G -A -module and the cohomology group  of G in B

    An X-ray characterization of the central region of the SNR G332.5-5.6

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    We present an X-ray analysis of the central region of supernova remnant (SNR) G332.5-5.6 through an exhaustive analysis of XMM-Netwon observations with complementary infrared observations. We characterize and discuss the origin of the observed X-ray morphology, which presents a peculiar plane edge over the west side of the central region. The morphology and spectral properties of the X-ray supernova remnant were studied using a single full frame XMM-Newton observation in the 0.3 to 10.0 keV energy band. Archival infrared WISE observations at 8, 12 and 24 \mu m were also used to investigate the properties of the source and its surroundings at different wavelengths. The results show that the extended X-ray emission is predominantly soft (0.3-1.2 keV) and peaks around 0.5 keV, which shows that it is an extremely soft SNR. X-ray emission correlates very well with central regions of bright radio emission. On the west side the radio/X-ray emission displays a plane-like feature with a terminal wall where strong infrared emission is detected. Our spatially resolved X-ray spectral analysis confirms that the emission is dominated by weak atomic emission lines of N, O, Ne, and Fe, all of them undetected in previous X-ray studies. These characteristics suggest that the X-ray emission is originated in an optically thin thermal plasma, whose radiation is well fitted by a non-equilibrium ionization collisional plasma (VNEI) X-ray emission model. Our study favors a scenario where G332.5-5.6 is expanding in a medium with an abrupt density change (the wall), likely a dense infrared emitting region of dust on the western side of the source.Comment: 7 pages, 5 figures and 2 tables. Accepted for publication in A&

    IR and electrochemical synthesis and characterization of thin films of PEDOT grown on platinum single crystal electrodes in [EMMIM]Tf2N ionic liquid

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    Thin films of PEDOT synthesized on platinum single electrodes in contact with the ionic liquid 1-ethyl-2,3-dimethylimidazolium triflimide ([EMMIM]Tf2N) were studied by cyclic voltammetry, chronoamperometry, infrared spectroscopy and atomic force microscopy. It was found that the polymer grows faster on Pt(111) than on Pt(110) or Pt(100) and that the redox reactions associated with the PEDOT p-doping process are much more reversible in [EMMIM]Tf2N than in acetonitrile. Finally, the ion exchange and charge carriers’ formation during the p-doping reaction of PEDOT were studied using in situ FTIR spectroscopy.APS acknowledges the scholarship “Estudiantes sobresalientes de posgrado” at the “Universidad Nacional de Colombia (UNAL)” and COLCIENCIAS National Doctoral Scholarship (567). MFS acknowledges support of UNAL (Research Project 19030). JMF thanks MINECO (Spain) support through project CTQ2013-44083-P and Generalitat Valenciana (Feder) through project PROMETEOII/2014/013

    Hydrogen redox reactions in 1-ethyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide on platinum single crystal electrodes

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    Hydrogen oxidation and the subsequent proton reduction are studied on platinum single crystal electrodes in purified 1-ethyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid. The hydrogen redox reaction shows some dependence of the surface orientation. The highest reversibility is observed with Pt(111) whereas the reaction in electrodes with {100} sites is less reversible and with a slow kinetics. Adsorption states are observed in the presence of hydrogen along with the main oxidation reaction. Also, it is possible to detect protons after oxidation of water and H2O2.APS is grateful to the National University of Colombia (ESP-2011-02) for the scholarship “Estudiantes sobresalientes de posgrado”, and to COLCIENCIAS (567-2012) for the national doctoral scholarship. MFS acknowledges support from the National University of Colombia (Research Project 19030). JMF acknowledges support from Generalitat Valenciana (Feder) (PROMETEO/2009/045) through project PROMETEO/2009/045

    Interaction of water with methanesulfonic acid on Pt single crystal electrodes

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    The electrochemical behavior of methanesulfonic acid on platinum single crystal electrode surfaces is investigated by cyclic voltammetry and infrared spectroscopy measurements. The results are compared with the voltammetric profiles of perchloric and trifluoromethanesulfonic acids. The differences are interpreted in terms of the effect of the anion on the structure of water. No adsorbed species are detected by infrared spectroscopy.APS acknowledges the scholarship “Estudiantes sobresalientes de posgrado” at the UNC and COLCIENCIAS National Doctoral Scholarship (567). MFS acknowledges the support of UNC (Research Project 19030). JMFwould like to thankGeneralitat Valenciana (Feder) through project PROMETEOII/2014/013

    Role of the interfacial water structure on electrocatalysis: Oxygen reduction on Pt(1 1 1) in methanesulfonic acid

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    Most of electrocatalytic reactions occur in an aqueous environment. Understanding the influence of water structure on reaction dynamics is fundamental in electrocatalysis. In this work, the role of liquid water structure on the oxygen reduction at Pt(1 1 1) electrode is analyzed in methanesulfonic (MTSA) and perchloric acids. This is because these different anions can exert a different influence on liquid water structure. Results reveal a lower ORR electrode activity in MTSA than in HClO4 solutions and they are discussed in light of anion's influence on water structural ordering. From them, the existence of an outer-sphere, rate determining, step in the ORR mechanism is suggested.This work has been carried out under MINECO project CTQ2013-44083-P (Spain). APSR acknowledges the scholarship “Estudiantes sobresalientes de posgrado” at the UNAL and COLCIENCIAS National Doctoral Scholarship (567). MFS acknowledges the support of UNAL (Research Project 19030)

    Evaluación de dos formulaciones de Bacillus thuringiensis H-14 para el control de larvas de Aedes aegypti

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    Two formulations of Bacillus thunngiensis H-14 were tested in the laboratory and field against Aedes aegypti larvae, a wettable powder (3.500 ANl) and liquid concentrate (1.000 AMI) (AA= Intemational A. aegypti Toxic Units). The laboratory tests were carried out with four different dosages of each formulations. The LD 99.9 was found. Residual action did not increase in direct proportion to the dosage. At a dose of 1,050 AA/l the residual-aciion was found to be 11 days for the wettable powder and 9.9 days for liquid concentrate. Daily adult emergence, as measured by retumig to 30% of pretreatment levels, was delayed 21.7 days when the wettable powder was applied and 18 days when the liquid concentrate. Daily adult emergence, as measured by returnig to 30% of pretreatment levels, was delayed 21.7 days when the wettable powder was applied and 18 days when the liquid concentrate was applied. Although statistically significant differences were found between different dosages and types of breeding containers, these differences have no operational importante. The field trials were done by appling a dose of 1.500 AA/1 to laundry tanks, drums and tires. A residual action against larvae of 9 days was obtained with the wettable powder and 7.2 with the liquid concentrate. B.t. H-14 was shown to be effective against all larva1 stages of A. aegypti in the breeding containers treated. Its use as an alternative larvicide has possibilities in special situations where chernical methods are undesirable or where other control method are not practical.Se evaluaron en el laboratorio y en condiciones naturales, dos formulaciones de Bacillus thuringiensis H-14, el cual es un insecticida microbiológico contra larvas de Aedes aegypti Se utilizó polvo humectable (3.500 AA/mg) y líquido concentrado (1.000 AA/mg) (AA = Unidades Tóxicas Internacionales en A. aegypti). Se calcularon las dosis letales (DL 99,9) para cada formulación. En una estación de laboratorio que simulaba las condiciones naturales de cría de A. aegypti, se realizaron pruebas con cuatro dosis diferentes de cada una de las dos formulaciones. Con una dosis de 1.050 AA/I, se encontró una acción residual de 11 días con el polvo humectable y de 9,9 días con el líquido concentrado. La acción residual no aumentó en proporción directa con la dosis. La tasa de emergencia diaria de adultos tardó 21,7 días en recuperarse hasta el 30% de su nivel de pretratamiento, cuando se aplicó polvo humectable y 18 días cuando se aplicó Iíquido concentrado. Aunque en las pruebas en condiciones seminaturales, se encontraron diferencias estadísticamente significativas entre las diferentes dosis y los diferentes tipos de criaderos, operacionalmente estas diferencias no tienen importancia práctica porque no aumenta el rendimiento de la medida de control. Los ensayos en condiciones naturales se realizaron aplicando una dosis de 1.050 AA/I a las albercas, toneles y llantas. El B. t. H-14 demostró ser efectivo, al causar 100% de mortalidad en todos los estadios larvarios de A. aegyptien los criaderos tratados. Se obtuvo una acción residual de 9 días en los criaderos cuando se aplicó polvo humectable y 7,2 días cuando se aplicó líquido concentrado. El uso del B. t. H-14. como larvicida alterno, tiene posibilidades en situaciones especiales, donde los métodos químicosson indeseadoso imprácticos

    An extensive K-bentonite as an indicator of a super-eruption in northern Iberia 477 My ago

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    Zircon and monazite ID-TIMS U-Pb dating of four Lower Ordovician altered ash-fall tuff beds (K-Bentonites) in NW Iberia provided coetaneous ages of 477.5±1, 477±1.3 Ma, 477.2±1.1 Ma and 477.3±1 Ma, with a pooled concordia age of 477.2±0.74 Ma. A conservative estimation of the volume and mass of the studied K-bentonite beds (using data from the Cantabrian Zone) returns a minimum volume for the preserved deposits of ca. 37.5 km3 (Volcanic Explosivity Index - VEI = 6, Colossal). When considering other putative equivalent beds in other parts of Iberia and neighbouring realms the volume of ejecta associated to this event would make it reach the Supervolcanic-Apocalyptic status (VEI=8, >1000 km3). Contrary to most cases of this kind of gargantuan eruption events, the studied magmatic event took place in relation to continental margin extension and thinning and not to plate convergence. We speculate that a geochronologically coincident large caldera event observed in the geological record of NW Iberia could be ground zero of this super-eruption

    Variaciones en los patrones de pigmentación y de color de larvas de poblaciones naturales de anofeles albimanus de Colombia

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    Color and pigmentation variants of Anopheles albimanus of third and fourth instar larvae were described from field populations in four different geogaphic and ecological areas in Colombia, together with their frecuency. These variants include three of the head capsule, nine of body pigmentation and of body color. Also, curved antennal sabers and antennal pigmentation are described. We report the ocurrence of high level of polymorphys in body color, pigmentation pattern and other visible traits. A brief description of each variant its frequency in each populations is included.Fueron observados el patrón de pigmentación y el color del cuerpo de las larvas de III y IV estadio en poblaciones naturales de Anopheles albimanus procedentes de cuatro áreas geográficas y ecológicas diferentes. Se incluyen tres variantes de la cápsula de la cabeza, el sable curvado de las antenas y la pigmentación; nueve variantes de la pigmentación del cuerpo y 17 del color del cuerpo. Se informa la alta variación en los patrones de color y otras características visibles. Se incluye una breve descripción de cada variante y la frecuencia observada en cada población

    Обширные отложения K-бентонитов как индикатор супервзрыва в северной Иберии на уровне 477 миллионов лет назад

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    Zircon and monazite ID-TIMS U-Pb dating of four Lower Ordovician altered ash-fall tuff beds (K-Bentonites) in NW Iberia provided coetaneous ages of 477.5±1, 477±1.3 Ma, 477.2±1.1 Ma and 477.3±1 Ma, with a pooled concordia age of 477.2±0.74 Ma. A conservative estimation of the volume and mass of the studied K-bentonite beds (using data from the Cantabrian Zone) returns a minimum volume for the preserved deposits of ca. 37.5 km3 (Volcanic Explosivity Index - VEI = 6, Colossal). When considering other putative equivalent beds in other parts of Iberia and neighboring realms the volume of ejecta associated to this event would make it reach the Supervolcanic-Apocalyptic status (VEI=8, >1000 km3). Contrary to most cases of this kind of gargantuan eruption events, the studied magmatic event took place in relation to continental margin extension and thinning and not to plate convergence. We speculate that a geochronologically coincident large caldera event observed in the geological record of NW Iberia could be ground zero of this super-eruption
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