1,208 research outputs found

    Contribución al conocimiento de la anapaita de la Cerdanya

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    Se estudian mineralógicamente los fosfatos miocénicos de Bellver de la Cerdanya (Lérida). Para ello, se emplean las técnicas siguientes: difracción de rayos X, espectroscopia de emisión y absorción de infrarrojos.Mediante el estudio roentgenológico determinamos que la especie mineral en estudio es la Anapaita (FeCa2(P04)2.4H2O). La espectroscopia de emisión confirma, por una parte, la existencia de los elementos constituyentes de la fórmula química: P, Ca y Fe con líneas bien marcadas y, por otra parte, la presencia de Mn, Al, Si, Mg, Na y Cu como contaminantes.Finalmente, el estudio del espectro de absorción de rayos infrarrojos detecta el grupo fosfato, básico, y la presencia de agua de absorción

    Contribución al conocimiento de la anapaita de la Cerdanya

    Get PDF
    Se estudian mineralógicamente los fosfatos miocénicos de Bellver de la Cerdanya (Lérida). Para ello, se emplean las técnicas siguientes: difracción de rayos X, espectroscopia de emisión y absorción de infrarrojos.Mediante el estudio roentgenológico determinamos que la especie mineral en estudio es la Anapaita (FeCa2(P04)2.4H2O). La espectroscopia de emisión confirma, por una parte, la existencia de los elementos constituyentes de la fórmula química: P, Ca y Fe con líneas bien marcadas y, por otra parte, la presencia de Mn, Al, Si, Mg, Na y Cu como contaminantes.Finalmente, el estudio del espectro de absorción de rayos infrarrojos detecta el grupo fosfato, básico, y la presencia de agua de absorción

    Effects of Thermal Radiation Using Wood Stoves on Population Health

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    The use of biomass for cooking food in the rural sector of the province of Manabí is very common. The present work analyzes the situation of families that use wood stoves for the cooking of food in the community of Casas Viejas, canton Jipipapa, province of Manabí. Thermography techniques have used to measure the level of emissivity to which users of traditional kitchens are exposed. It was determined that the exposure is direct and reaches temperatures up to 250 ° C, being able to raise its body temperature in the abdominal area up to 80 ° C. This periodic and prolonged exposure to thermal radiation can seriously affect the health of users

    Trophic consequences of introduced species: comparative impacts of increased inter-specific versus intra-specific competitive interactions

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    1. Invasive species can cause substantial ecological impacts on native biodiversity. Whilst ecological theory attempts to explain the processes involved in the trophic integration of invaders into native food webs and their competitive impacts on resident species, results are equivocal. In addition, quantifying the relative strength of impacts from non-native species (inter-specific competition) versus the release of native conspecifics (intra-specific competition) is important but rarely completed. 2. Two model non-native fishes, the globally invasive Cyprinus carpio and Carassius auratus, and the model native fish Tinca tinca, were used in a pond experiment to test how increased intra- and inter-specific competition influenced trophic niches and somatic growth rates. This was complemented by samples collected from three natural fish communities where the model fishes were present. The isotopic niche, calculated using stable isotope data, represented the trophic niche. 3. The pond experiment used additive and substitutive treatments to quantify the trophic niche variation that resulted from intra- and inter-specific competitive interactions. Although the trophic niche sizes of the model species were not significantly altered by any competitive treatment, they all resulted in patterns of inter-specific niche divergence. Increased inter-specific competition caused the trophic niche of T. tinca to shift to a significantly higher trophic position, whereas intra-specific competition caused its position to shift towards elevated 13C. These patterns were independent of impacts on fish growth rates, which were only significantly altered when inter-specific competition was elevated. 4. In the natural fish communities, patterns of trophic niche partitioning between the model fishes was evident, with no niche sharing. Comparison of these results with those of the experiment revealed the most similar results between the two approaches were for the niche partitioning between sympatric T. tinca and C. carpio. 5. These results indicate that trophic niche divergence facilitates the integration of introduced species into food webs, but there are differences in how this manifests between introductions that increase inter- and intra-specific competition. In entirety, these results suggest that the initial ecological response to an introduction appears to be a trophic re-organisation of the food web that minimises the trophic interactions between competing species

    Gas-Phase Errors Affect DFT-Based Electrocatalysis Models of Oxygen Reduction to Hydrogen Peroxide

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    Electrochemical production of H2O2 is more benign and affordable than the conventional route, yet its adoption requires the discovery of robust, cost-effective catalysts. DFT-based models lead to conspicuous breakthroughs but had some known limitations, for instance the poor description of molecules with certain chemical bonds. Here, the errors in H2O2 and O2 displayed by various GGAs, meta-GGAs and hybrids were assessed and semi empirically corrected. The errors in O2 with respect to experiments were in the range of −0.95 to −0.22 eV, whereas those in H2O2 spanned from −0.53 to −0.04 eV. Thus, single and double O−O bonds were poorly described in general, and the errors were nearly twice as negative for double bonds. Furthermore, these errors introduced large deviations in the predictions of free energies for O2 reduction to H2O2, and the equilibrium potentials and optimal adsorption energies of *OOH could either be sizably overestimated or underestimated

    Nambu-Poisson manifolds and associated n-ary Lie algebroids

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    We introduce an n-ary Lie algebroid canonically associated with a Nambu-Poisson manifold. We also prove that every Nambu-Poisson bracket defined on functions is induced by some differential operator on the exterior algebra, and characterize such operators. Some physical examples are presented

    The role of histidine residues in modulation of the rat P2X 2 purinoceptor by zinc and pH

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65774/1/jphysiol.2001.013244.pd

    Status of Tuna Resources in the Zambales Coast

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    This study aimed to generate and assess the 10-year (2003-2012) data on estimated annual yield of tuna, the catch per unit effort (CPUE) of dominant fishing gears, catch composition, seasonality, and size composition of tuna species in Zambales Coast. This is in support to the implementation of the National Tuna Management Plan. Results were based on the landed catch recorded at the identified sampling site in major fish landing centers in Zambales. The tuna catch in Zambales showed an increasing trend from 2005 to 2011,the highest catch was observed in 2011 with 12,968 MT. The major tuna fishing gears observed in the area were purse seine, multiple handline, and ring net. The CPUE of the three dominant tuna fishing gears showed that purse seine, a commercial fishing gear, has the highest average CPUE with 1,678.52 kg/day, followed by ring net with 222.07 kg/day, and multiple handline, which is a municipal fishing gear, with 62.94 kg/day. There were eight species of tuna being caught in Zambales Coast. The most dominant species caught were skipjack tuna (Katsuwonus pelamis), followed by yellowfin tuna (Thunnus albacares), and bigeye tuna (Thunnus obesus). The monthly seasonal distribution of the three dominant tuna species was also assessed. Peak in the catch of Katsuwonus pelamis was recorded in the first quarter of the year. For Thunnus albacares, the highest catch was observed during the second and third quarter. The bulk of catch for Thunnus obesus appeared on every first and second quarter of the year. All of these species were observed to have almost consistent production in the remaining quarters of every year. Data on size composition of tuna revealed that most of the tuna species landed in Zambales were caught before they reach the length at first maturity. Among species caught, Thunnus albacares and Thunnus obesus recorded the highest percentage of small tuna

    Symplectic connections and Fedosov's quantization on supermanifolds

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    A (biased and incomplete) review of the status of the theory of symplectic connections on supermanifolds is presented. Also, some comments regarding Fedosov's technique of quantization are made.Comment: Submitted to J. of Phys. Conf. Se
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