5,471 research outputs found

    OH rotational lines as a diagnostic of the warm neutral gas in galaxies

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    We present Infrared Space Observatory (ISO) observations of several OH, CH and H2O rotational lines toward the bright infrared galaxies NGC253 and NGC1068. As found in the Galactic clouds in SgrB2 and Orion, the extragalactic far-IR OH lines change from absorption to emission depending on the physical conditions and distribution of gas and dust along the line of sight. As a result, most of the OH rotational lines that appear in absorption toward NGC253 are observed in emission toward NGC1068. We show that the far-IR spectrum of OH can be used as a powerful diagnostic to derive the physical conditions of extragalactic neutral gas. In particular, we find that a warm (Tk~150 K, n(H2)< 5 10^4 cm^-3) component of molecular gas with an OH abundance of 10^{-7} from the inner <15'' can qualitatively reproduce the OH lines toward NGC253. Similar temperatures but higher densities (5 10^5 cm^-3) are required to explain the OH emission in NGC1068.Comment: 5 pages, 4 figures, accepted in ApJ Part I (2004, October 6

    Super-Nernstian Shifts of Interfacial Proton-Coupled Electron Transfers : Origin and Effect of Noncovalent Interactions

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    The support of the University of Aberdeen is gratefully acknowledged. C.W. acknowledges a summer studentship from the Carnegie Trust for the Universities of Scotland. E.P.M.L. acknowledges SeCYT (Universidad Nacional de Cordoba), ́ CONICET- PIP 11220110100992, Program BID (PICT 2012-2324), and PME 2006-01581 for financial support.Peer reviewedPostprin

    Epidemiology of salmonellosis in sow units of Catalonia (Spain)

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    A bacteriological study aimed to the detection of sows excreting Salmonella was carried out in 74 sow units. Individual faecal samples were collected and a detailed questionnaire was filled in each farm and the data gathered were used in a bivariate logistic regression analysis to determine risk factors for Salmonella positivity. In 18 farms (24.32 %) Salmonella carriers were detected. Of the total 1480 samples analysed, 50 were positive (3.38 %), accounting for 11 different serotypes. Within positive farms, 13.8 % of sows were positive. Epidemiologic analysis of the results showed three main risk factors: to have open-flushed drainage of slurry, rodent control, and the number of sows in the unit. Our results showed that, in infected farms, the proportion of sows actively excreting Salmonella was considerably high (3.38 %). This fact, and the risk factors detected should be taken into account when designing effective plans for the control of salmonellosis in sows

    Design of optimal material properties for structures composed of nonlinear material

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76247/1/AIAA-1994-4367-370.pd

    Comparison of two commercial ELISA for the diagnosis of salmonellosis in swine

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    Three hundred and sixty-one pig sera collected in farms of Catalonia were randomly selected from a serum bank. Samples were examined by using two commercial ELISA kits. Results were compared with the kappa value using WinEpiscope. Besides, sample/positive ratios (S/P) were calculated. Comparison of results of both ELISA yielded a poor agreement (kappa 0.191), indicating that both ELISA did not measure the same. In addition, when raw optical densities were compared by means of a regression analysis, the results indicated a low correlation (r = 0.54 ). The results of this study clearly indicate that results of both kits are not interchangeable and that normalization of results by using S/P ratios did not serve to improve the agreement between tests. From our results, it is tempting to suggest that Salmotype detects a greater number of IgM positive pigs. The nature of these IgMs (salmonella-specific or not) is not known to us at this moment

    'Enhancement of the crystallization process of TbxFe1-x thin films upon the formation of alpha-Tb phase'

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    TbxFe1−x thin films deposited by sputtering on Mo were investigated structurally and magnetically. The microstructure consists of TbFe2 nanoparticles embedded in an amorphous matrix, and the Tb content can be correlated with an increase in the volume of these nanoparticles. Similar microstructure and behavior were found when TbFe2 was deposited on glass and on a Pt buffer layer. Nevertheless, thermal treatments promote a different effect, depending on the mechanical stiffness of the buffer layer. The layers deposited on Mo, a rigid material, show crystalline TbFe2 together with α-Tb phase upon thermal treatment. In contrast, TbFe2 does not crystallize properly on Pt, a material with a lower stiffness than Mo. Intermediate results were observed on the film deposited on glass. Experimental results show the impact of the buffer stiffness on the crystallization process. Moreover, the formation of α-Tb appears to be fundamental to crystallized TbFe2 on layers deposited on rigid buffer

    Distance to flood meadows as a predictor of use of Nothofagus pumilio forest by livestock and resulting impact, in Patagonia, Argentina

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    Seedling browsing by livestock has been indicated as major threat for forest sustainability use. Nothofagus pumilio forests are part of the livestock raising system in Patagonia, but because of the sparse understory cover, livestock graze mainly on flood meadows within the forest matrix. The complexity of the environment under study (forests and flood meadows) means that an adaptive predictor is needed to evaluate the intensity of resource use by livestock in order to assess its effect on the forest. Distance to flood meadows was evaluated as a predictor of the use intensity of the forest by livestock and its effect on the understory. The study was conducted at three sites in Chubut Province, Patagonia-Argentina. We established transects in the forest 320 m long, starting at the edge flood meadow-forest. In these transects, the livestock presence indicators (soil compaction, density of feces and trails) and composition of the understory were evaluated. Generalized Linear Model for repeated measures for longitudinal data were used. The indicators showed that distance is efficient for estimating forest use intensity by livestock. The understory varied with distance, the cover of exotic herbaceous was higher near the flood meadow. Far from the flood meadow, the cover was entirely composited of native species. The results support the use of distance to flood meadows as a tool for decision making in livestock and forest management in N. pumilio forests, and for further research on livestock effect on the forest.Fil: Quinteros, Claudia Pamela. Centro de Investigación y Extensión Forestal Andino Patagónico; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lopez Bernal, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina. Centro de Investigación y Extensión Forestal Andino Patagónico; ArgentinaFil: Gobbi, Miriam E.. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bava, Jose Omar. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina. Centro de Investigación y Extensión Forestal Andino Patagónico; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
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