377 research outputs found

    Occurrence and infectivity of vesicular-arbuscular mycorrhizal fungi in north-western Italy vineyards

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    12 vineyards were surveyed during one year to assess root VA infection and spare population in the soil. 9 fungal species were present; 3 of them were more common and could be reinoculated successfully on grapevine. Other crops, in sites close to the vineyard sampled, often contained a different population of species. More species were present in soils of pH > 7.5.Spores were most abundant in autumn, their number decreasing in spring. Soils with least P and higher pH contained more spores. Root infection was unrelated to spare frequency or soil characters.Infectivity of the soil on grapevine plants, assessed by means of the MPN method, was weil related to the number of spores present in the soil at the same time, if roots were removed. lt is concluded that spore numbers can express the ability of the soil to infect plants, thus showing where artificial inoculation could be potentially more effective

    Numerical Simulation of the Performance of a Twin Scroll Radial Turbine at Different Operating Conditions

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    Twin scroll radial turbines are increasingly used for turbocharging applications, to take advantage of the pulsating exhaust gases. In spite of its relevance in turbocharging techniques, scientific literature about CFD applied to twin scroll turbines is limited, especially in case of partial admission. In the present paper a CFD complete model of a twin scroll radial turbine is developed in order to give a contribution to literature in understanding the capabilities of current industrial CFD approaches applied to these difficult cases and to develop performance index that can be used for turbine design optimization purposes. The flow solution is obtained by means of ANSYS CFX \uae in a wide range of operating conditions in full and partial admission cases. The total-to-static efficiency and the mass flow parameter (MFP) have been calculated and compared with the experimental database in order to validate the numerical model. The purpose of the developed procedure is also to generate a database for twin scroll turbines useful for future applications. A comparison between performances obtained in different admission conditions was performed. In particular the analysis focused on the characterization of the flow at volute outlet/rotor inlet section. A flow distortion index at rotor inlet was introduced to correlate the turbine performance and the flow nonuniformities generated by the volute. Finally the influence of the backside cavity on the performance parameters is also discussed. The introduction of these new nonuniformity indices is proposed for volute design and optimization procedures

    Comparison of J-r test techniques under gaseous hydrogen environment

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    Respuesta humoral y consecuencias reproductivas en ovejas desafiadas con Brucella ovis al final de la gestación

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    La brucelosis ovina por Brucella ovis es una enfermedad de prevalencia alta en Argentina. Para evaluar la patogenicidad de B. ovis y la respuesta serológica durante el último mes de gestación, 6 ovejas se distribuyeron en dos grupos: G1, ovejas preñadas, n = 4 y G2, ovejas no preñadas, n = 2. Tres ovejas del G1 (15 días preparto) y una del G2 fueron inoculadas con B. ovis. Se analizaron muestras de suero mediante diferentes pruebas serológicas. Se realizó aislamiento y PCR a partir de mucus cérvico-vaginal (mcv), placenta y leche. En las muestras de placenta se realizó histopatología. Las hembras del G1 parieron corderos vivos; se detectaron anticuerpos en las ovejas desafiadas del G1 a partir de los 5 días posinoculación. El mcv de las ovejas desafiadas resultó negativo al aislamiento en ambos grupos. Las muestras de leche del G1 fueron positivas por cultivo y PCR a B. ovis. La técnica de PCR resultó positiva en las placentas de las ovejas desafiadas del G1. La histopatología reveló una placentitis necrótica supurativa en una de las ovejas desafiadas. El desafío con B. ovis preparto resultó en la invasión de la placenta y de la glándula mamaria, con la consecuente excreción de la bacteria por leche. La infección con B. ovis indujo una respuesta humoral temprana en las ovejas. La colonización de la placenta por B. ovis y la excreción de la bacteria por la leche sugieren un potencial riesgo de infección activa para los corderos y la posibilidad de que estos se comporten como portadores latentes de la infección.Ovine brucellosis by Brucella ovis is a highly prevalent disease in Argentina. This study aimed to evaluate the pathogenicity of B. ovis and the serological response in ewes during late pregnancy and in their offspring. Six adult ewes were distributed in two groupsG1 (pregnant females, n = 4) and G2 (nonpregnant females, n = 2). Three pregnant ewes at 15 days prepartum and one nonpregnant eve were inoculated with B. ovis. Sera of sheep and their offspring were analyzed by different serological tests. Samples of cervicovaginal mucus, placenta and milk were studied by bacteriology. A Brucella genus-specific PCR assay was carried out in placenta and milk samples. Placenta samples were hystopathologically processed. G1 females gave birth to live lambs, but one died hours postpartum. Serological techniques employed detected antibodies in serum of inoculated pregnant animal 5 days postchallenge. Sera of female controls G1 and G2 remained negative throughout the study. Cervicovaginal mucus of infected ewes in G1 and G2 yielded negative results to bacteriology, but B. ovis was isolated from milk. The PCR assay was positive for the placenta and milk from inoculated pregnant ewes. Histopathology revealed necrotic suppurative placentitis in one placenta. However, although results demonstrated that B. ovis can invade the placenta and mammary gland, this bacterium did not cause abortion when it was inoculated intravenously at 15 days prepartum. B. ovis infection induced an early humoral response in pregnant ewes, but their lambs remained seronegative, indicating that there was no transfer of antibodies in infancy. Placenta colonization and milk excretion of B. ovis involves a potential source of infection for lambs, which could play a role as latent carriers of infection

    Metamodels of a gas turbine powered marine propulsion system for simulation and diagnostic purposes

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    The paper presents the application of artificial neural network for simulation and diagnostic purposes applied to a gas turbine powered marine propulsion plant. A simulation code for the propulsion system, developed by the authors, has been extended to take into account components degradation or malfunctioning with the addition of performance reduction coefficients. The above coefficients become input variables to the analysis method and define the system status at a given operating point. The simulator is used to generate databases needed to perform a variable selection analysis and to tune response surfaces for both direct (simulation) and inverse (diagnostic) purposes. The application of the methodology to the propulsion system of an existing frigate version demonstrate the potential of the approach

    Immune response and reproductive consequences in experimentally infected ewes with Brucella ovis during late pregnancy

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    La brucelosis ovina por Brucella ovis es una enfermedad de prevalencia alta en Argentina. Para evaluar la patogenicidad de B. ovis y la respuesta serológica durante el último mes de gestación, 6 ovejas se distribuyeron en dos grupos: G1, ovejas preñadas, n = 4 y G2, ovejas no preñadas, n = 2. Tres ovejas del G1 (15 días preparto) y una del G2 fueron inoculadas con B. ovis. Se analizaron muestras de suero mediante diferentes pruebas serológicas. Se realizó aislamiento y PCR a partir de mucus cérvico-vaginal (mcv), placenta y leche. En las muestras de placenta se realizó histopatología. Las hembras del G1 parieron corderos vivos; se detectaron anticuerpos en las ovejas desafiadas del G1 a partir de los 5 días posinoculación. El mcv de las ovejas desafiadas resultó negativo al aislamiento en ambos grupos. Las muestras de leche del G1 fueron positivas por cultivo y PCR a B. ovis. La técnica de PCR resultó positiva en las placentas de las ovejas desafiadas del G1. La histopatología reveló una placentitis necrótica supurativaen una de las ovejas desafiadas. El desafío con B. ovis preparto resultó en la invasión de la placenta y de la glándula mamaria, con la consecuente excreción de la bacteria por leche. La infección con B. ovis indujo una respuesta humoral temprana en las ovejas. La colonización de la placenta por B. ovis y la excreción de la bacteria por la leche sugieren un potencial riesgo de infección activa para los corderos y la posibilidad de que estos se comporten como portadores latentes de la infección.Ovine brucellosis by Brucella ovis is a highly prevalent disease in Argentina. This study aimed to evaluate the pathogenicity of B. ovis and the serological response in ewes during late pregnancy and in their offspring. Six adult ewes were distributed in two groupsGI (pregnant females, n = 4) and G2 (nonpregnant females, n = 2). Three pregnant ewes at 15 days prepartum and one nonpregnant eve were inoculated with B. ovis. Sera of sheep and their offspring were analyzed by different serological tests. Samples of cervicovaginal mucus, placenta and milk were studied by bacteriology. A Brucella genus-specific PCR assay was carried out in placenta and milk samples. Placenta samples were hystopathologically processed. G1 females gave birth to live lambs, but one died hours postpartum. Serological techniques employed detected antibodies in serum of inoculated pregnant animal 5 days postchallenge. Sera of female controls G1 and G2 remained negative throughout the study. Cervicovaginal mucus of infected ewes in G1 and G2 yielded negative results to bacteriology, but B. ovis was isolated from milk. The PCR assay was positive for the placenta and milk from inoculated pregnant ewes. Histopathology revealed necrotic suppurative placentitis in one placenta. However, although results demonstrated that B. ovis can invade the placenta and mammary gland, this bacterium did not cause abortion when it was inoculated intravenously at 15 days prepartum. B. ovis infection induced an early humoral response in pregnant ewes, but their lambs remained seronegative, indicating that there was no transfer of antibodies in infancy. Placenta colonization and milk excretion of B. ovis involves a potential source of infection for lambs, which could play a role as latent carriers of infection.Fil: Paolicchi, Fernando Alberto. Instituto Nacional de Tecnología Agropecuaria; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Nuñez, Marta. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Fiorentino, Maria Andrea. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Malena, Rosana C.. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Trangoni, Marcos. Instituto Nacional de Tecnología Agropecuaria. Centro Nacional de Investigaciones Agropecuarias. Centro de Investigación de Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; ArgentinaFil: Cravero, Silvio Lorenzo Pedro. Instituto Nacional de Tecnología Agropecuaria. Centro Nacional de Investigaciones Agropecuarias. Centro de Investigación de Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; ArgentinaFil: Estein, Silvia Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil. Centro de Investigacion Veterinaria de Tandil; Argentin

    YqiC of Salmonella enterica serovar Typhimurium is a membrane fusogenic protein required for mice colonization

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    <p>Abstract</p> <p>Background</p> <p><it>Salmonella enterica </it>serovar Typhimurium is an intracellular bacterial pathogen which can colonize a variety of hosts, including human, causing syndromes that vary from gastroenteritis and diarrhea to systemic disease.</p> <p>Results</p> <p>In this work we present structural information as well as insights into the <it>in vivo </it>function of YqiC, a 99-residue protein of <it>S</it>. Typhimurium, which belongs to the cluster of the orthologous group 2960 (COG2960). We found that YqiC shares biophysical and biochemical properties with <it>Brucella abortus </it>BMFP, the only previously characterized member of this group, such as a high alpha helix content, a coiled-coil domain involved in trimerization and a membrane fusogenic activity <it>in vitro</it>. In addition, we demonstrated that YqiC localizes at cytoplasmic and membrane subcellular fractions, that a <it>S</it>. Typhimurium <it>yqiC </it>deficient strain had a severe attenuation in virulence in the murine model when inoculated both orally and intraperitoneally, and was impaired to replicate at physiological and high temperatures <it>in vitro</it>, although it was still able to invade and replicate inside epithelial and macrophages cell lines.</p> <p>Conclusion</p> <p>This work firstly demonstrates the importance of a COG2960 member for pathogen-host interaction, and suggests a common function conserved among members of this group.</p

    Multidimensional integration of RDF datasets

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    Data providers have been uploading RDF datasets on the web to aid researchers and analysts in finding insights. These datasets, made available by different data providers, contain common characteristics that enable their integration. However, since each provider has their own data dictionary, identifying common concepts is not trivial and we require costly and complex entity resolution and transformation rules to perform such integration. In this paper, we propose a novel method, that given a set of independent RDF datasets, provides a multidimensional interpretation of these datasets and integrates them based on a common multidimensional space (if any) identified. To do so, our method first identifies potential dimensional and factual data on the input datasets and performs entity resolution to merge common dimensional and factual concepts. As a result, we generate a common multidimensional space and identify each input dataset as a cuboid of the resulting lattice. With such output, we are able to exploit open data with OLAP operators in a richer fashion than dealing with them separately.This research has been funded by the European Commission through the Erasmus Mundus Joint Doctorate Information Technologies for Business Intelligence-Doctoral College (IT4BI-DC) program.Peer ReviewedPostprint (author's final draft
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