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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Melamine cyanurate complexes and oxidative stress markers in trout kidney following melamine and cyanuric acid long term co-exposure and withdrawal
No full textIn 2007, renal failure and death in pets were linked to pet food containing both melamine (MEL) and cyanuric acid (CYA). In mammals and fish, the co-administration of MEL and CYA causes renal crystal formation. Moreover, little is known about the process of crystal removal in fish. The aim of this study was to evaluate the formation of MEL-cyanurate crystals in kidney of rainbow trout (Oncorhynchus mykiss) fed combined MEL and CYA diets for 10 weeks at 250, 500 and 1,000 mg/kg in feed (equivalent to 2.5, 5, 10 mg/kg body weight of trout fed 1 % body weight per day). During the exposure trial and throughout a withdrawal period, prooxidant effects of MEL and CYA were evaluated on oxidative stress markers such as catalase, glutathione S-transferase and malondialdehyde. Crystal formation was dose and time dependent, and after six withdrawal weeks, crystals persisted in kidney of trout treated the highest triazine dose. Catalase and glutathione S-transferase activity in kidney of trout exposed to both triazines for 10 weeks indicated that MEL (with or without CYA) can exert a higher prooxidant effect than CYA dispensed singly. Although the enzymes activity increase appears to be reverted after two MEL withdrawal weeks, persistence of crystals may lead to severe damage in renal cells of fish
Detoxifying response in juvenile tench fed by selenium diet
No full textThe effects of a selenium (Se) diet (1.0 mg Se kg−1) were investigated on growth, accumulation and antioxidant response in juvenile Tinca tinca at three endpoints (0, 4 and 8 weeks). Growth and condition factor (K > 1.5) for both control (0.25 mg Se kg−1) and Se tench were not significantly affected. Se exposed fish exhibited the highest Se level in the kidney and the liver after 4 weeks. By feeding more Se the accumulation capacity of tench did not increase and a plateau, mainly for the liver, was thus reached. Se level remained almost constant in the muscle if compared to own control and for each endpoint.
Superoxide dismutase activity in both tissues was not affected by Se supplementation and the higher catalase level in the kidney might support the hypothesis that the enzyme was adequate to remove the hydrogen peroxide production following Se exposure. However, supplemented diet with higher Se level could be critical for tench, as it may cause a lowering of glutathione peroxidase and glutathione reductase activities facilitating the onset of oxidative damage. The enhancement of thiol level and glutathione S-transferase activity, mainly in the liver, could be the signals of the only protection against the oxidative damage induced by Se
Antioxidant biomarker survey ensuing long-term selenium withdrawal in Acipenser baeri fed Se-cysteine diets
No full textTwo selenium withdrawal periods, 30 and 90 days, were considered for sturgeon fed 90 days three Se-cysteine diets (1.25, 5, 20 mg kg(-1)). Subsequently Acipenser baeri was fed the previous control diet (0.32 mg Se kg(-1)) for 90 days. Levels of superoxide dismutase, catalase, glutathione peroxidases, glutathione reductase, glyoxalase-II and malondialdehyde were determined in liver and kidney. Chemical analyses were carried out for the same tissues and for muscle. A reduction of Se levels in all tissues was recorded and the metalloid concentration decreased more quickly in liver than in kidney and muscle. At the end of the withdrawal Se concentration in muscle remained high in specimens previously fed 20 mg Se kg(-1) diet, and disturbance of key antioxidant enzymes was recorded in liver and kidney. Moreover, alterations in glutathione peroxidases, and glyoxalase-II activities persisted even after 90 withdrawal days and were indicative of oxidative stress induced by Se-cysteine concentrations. (C) 2014 Elsevier B.V. All rights reserved
Bioaccumulation in tissues of freshwater crayfish {\it Procambarus clarkii}fed a diet enriched in Selenium
No full textVariations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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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