1,721,211 research outputs found

    Iron demand by thermophilic and mesophilic bacteria isolated from an Antarctic geothermal soil

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    The thermophilic bacterial strain MP4 assigned to a new species, likely of the genus Alicyclobacillus, was isolated from geothermal soils on the NW slope of Mount Melbourne, Antarctica. These soils have high iron concentrations and the strain MP4 requires iron additions for growth. Four mesophilic bacterial strains Paenibacillus validus MP5, MP8, and MP10, and P. apiarius MP7, isolated from the same site, need iron supply for growth depending on the medium. Growth temperature of thermophilic strain ranges from 42 to 70 degrees C, and that one of mesophiles from 25 to 44 degrees C. Thermophilic and mesophilic strains shared microenvironments with temperature of 42-44 degrees C and showed optima of pH values ranging from 5.5 to 6.0. The thermophilic strain MP4 reached values of 10(6) CFU ml(-1) in aqueous soil extract from the NW slope of Mt. Melbourne, and 10(5) CFU ml(-1) in water extracts from other geothermal Antarctic areas ( Mt. Rittmann and Cryptogam Ridge). Growth of thermophilic bacteria in aqueous extracts of the NW slope of Mount Melbourne soils caused a reduction of 50% of soluble iron content, which was recovered in bacterial biomass. These results suggest a possible involvement of the thermophilic strain MP4 in iron bioavailability in these geothermal soils

    Going Beyond Counting First Authors in Author Co-citation Analysis

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    The present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed

    Variations on the Author

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    “Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship

    Appropriate Similarity Measures for Author Cocitation Analysis

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    We provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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