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    Immunoaffinity clean-up and direct fluorescence measurement of aflatoxins B1 and M1 in pig liver: comparison with high-performance liquid chromatography determination

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    An improved analytical method for aflatoxin B-1 ( AFB(1)) and aflatoxin M-1 ( AFM(1)) determination in pig liver is described, using an aqueous methanol extraction, an immunoaffinity column clean-up step and a direct fluorometric measurement for toxin detection and quantification. A detection limit of 1.0 mu g kg(-1) was achieved for AFB(1) and AFM(1). Mean recoveries of 80.7 +/- 9.0% for AFB(1) spiked at 1.0-9.7 mg kg(-1) levels and of 76.7 +/- 6.6% for AFM1 spiked at 1.0-5.5 mg kg(-1) levels were obtained. Recovery data for spiked samples were statistically compared with those obtained by the same extract using classical reversed-phase high-performance liquid chromatography ( RP-HPLC) with fluorescence detection, showing a significant correlation ( p <= 0.05) for both aflatoxins. Both procedures were applied to the analysis of 50 pig livers, collected from 10 farms in the north of Italy. All the samples showed a contamination level lower than 1.0 mu g kg(-1) for AFB(1) and one liver sample has shown an AFM(1) contamination greater than 1.0 mg kg(-1). The direct fluorometric procedure is particularly suitable for food manufacturers and control laboratories where quick procedures are mainly required for food quality control as well as for diagnostic and research purposes

    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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