1,720,998 research outputs found
Development and validation of a method for determination of 17 endocrine disrupting chemicals in milk, water, blood serum and feed by UHPLC-MS/MS
No full text: The concern for human exposure to bisphenol A (BPA) has led to the introduction of other bisphenols to be used as substitutes in industrial processes. These compounds show activity similar to BPA as endocrine disruptors and could be already widespread both in the environment and in food. To monitor their possible occurrence in the food chain, an analytical method based on affinity chromatography clean-up and UHPLC coupled to tandem mass spectrometry detection was developed and in-house validated according to European law, for simultaneous determination of 17 bisphenols in milk and blood serum from bovine and buffalo, in drinking water and in feed. The analytical performance parameters of the method for these matrices were determined. The results showed satisfactory precision in terms of relative standard deviation (3.3%-21.4%), overall good trueness as mean percentage recoveries (77.0%-119.4%), with the only exception of bisphenol PH and bisphenol S in milk and BPA diglycidyl ether in serum. The high specificity and sensitivity of the method allowed us to determine the analytes at very low concentrations, that is, 0.01-1.0 ng/mL in water, 0.1-2.0 ng/mL in milk, 0.01-1.0 ng/g in blood serum and 1.0-10.0 ng/g in feed
Occurrence of bisphenol A in the milk chain: A monitoring model for risk assessment at a dairy company
No full textBisphenol A (BPA) as a chemical hazard may enter the milk chain during primary production at the farm and, successively, during milk processing at a dairy company. To identify the potential pathways that play a role in the occurrence of BPA, a monitoring model for risk assessment based on the identification of the hazards at each stage of milk processing was investigated. Milk samples were analyzed using liquid chromatography with fluorescence detection. Quantifiable levels were detected in samples obtained from the raw milk storage tank, pasteurized milk from the storage tank, and packaged milk. The highest BPA contamination levels were detected in raw milk from the storage tank (mean 0.265 μg/L). Despite the fact that dietary exposure levels were below the temporary daily intake, BPA may have adverse effects, particularly for vulnerable population groups. New monitoring programs involving each stage of milk processing should therefore be applied
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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