1,720,956 research outputs found
Perfluoroalkyl acids in fish of Italian deep lakes: Environmental and human risk assessment
No full textDetermination of 20 PFASs in a fish species (Alosa agone) of commercial interest has been carried out in five Italian subalpine lakes to assess the risk for humans and predators for fish consumption. PFOS still presents the highest concentrations (0.9-16.6 ng g(-1) ww) among the analysed PFASs, in spite of its normative restrictions. PFOS concentrations measured in all lakes, except in Lake Maggiore, are homogeneous with an average of 3.1 +/- 1.9 ng g(-1) ww, which could be considered the "anthropogenic background concentration" of PFOS in fish of lakes located in an industrialised and urbanised region but without point sources. In Lake Maggiore, fish concentrations always exceed the EU EQSbiota (9.1 ng g(-1) ww) based on human fish consumption. Considering the effective consumption of fish in this area, an actual risk for fish consumption by humans is not evidenced, while a moderate risk of secondary poisoning for predators is highlighted. PFOA has been detected in significant concentration only in one sample in Lake Maggiore, while long chain PFCAs have been detected without significant differences among the lakes (0.3 to 2.7 ng g(-1) ww). The present study demonstrates that biota monitoring of fish can be used as a valuable tool to classify the quality status of water bodies regarding bioaccumulative PFAAs, even if the water concentrations are close to the reachable detection limits. (c) 2018 Published by Elsevier B.V
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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