1,720,975 research outputs found
Biomonitoring data as a tool for assessing mycotoxins exposure of workers
Get PDFAflatoxins are toxic compounds naturally occurring in crops mainly produced by molds of the genus Aspergillus. They represent the most concerning class of agricultural contaminants with a focus on aflatoxin B1 (AFB1) since it can act as etiological agent for hepatocarcinogenesis and immunosuppression. The corresponding working protocols were focused on the quantification of AFB1 and its main metabolites in urine and serum samples of workers potentially exposed during their occupational hours in different industrial settings, namely corn-based feed production company. Biological samples of 61 workers (32 exposed and 29 control group) were collected over a week (Monday and Friday). In urine, only aflatoxin M1 (13% in exposed and 11% in control) was found; in serum, 6.1% of samples revealed AFB1 presence (9,7% in exposed and 1.9% in control). However, neither difference between the average levels of exposed and control groups nor difference between levels of Friday and Monday deliveries were found. Ochratoxin A (OTA) was also tested and found in all serum samples with 33% of the samples having a concentration higher than the limit of quantification (LOQ) and the remaining between the limit of detection (LOD) and LOQ. Moreover, for OTA, a good correlation was found between Friday and Monday OTA levels
Evaluation of statistical treatment of left-censored contamination data: example on Deoxynivalenol occurrence in pasta and pasta substitute products
No full textThe handling of data on food contamination frequently represents a challenge because they are often left censored, i.e., they are composed by both positive and non-detected values; the latter observations are not quantified and provide only the information that they are below a lab-specific threshold value.
Besides deterministic approaches, that simplify the treatment by substituting non-detected values by fixed threshold or null values, there has been a growing interest in the application of stochastic approaches to the treatment of not quantified values. In this study, a Multiple Imputation method is applied to analyse contamination data on deoxynivalenol (DON), a mycotoxin that may be present in pasta and pasta substitute products.
An application of the proposed method to left-censored DON occurrence data is provided and the results are compared to those attained by using deterministic (substitution methods) methodologies. In this context, the stochastic approach seems to provide a more accurate, unbiased and realistic solution to the problem of left-censored occurrence data, with DON contamination mean values of the food considered equal to 139.4 μg/kg with a 95% confidence interval ranging from 137.0 to 141.9 μg/kg, in which lower and upper bound values of the substitution methods are included (128.1 μg/kg and 160.8 μg/kg respectively).
The obtained sample of occurrence values may represent a suitable dataset to be used in the assessment of dietary exposure scenarios of the general population
Valutazione della esposizione derivante dalla presenza di micotossine negli alimenti per l'infanzia
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Optimization and validation of a LC-HRMS method for aflatoxins determination in urine samples
Get PDFMycotoxins’ exposure by inhalation and/or dermal contact can occur in different branches of industry especially where heavily dusty settings are present and the handling of dusty commodities is performed. This study aims to explore the possible contribution of the occupational exposure to aflatoxins by analysing urine samples for the presence of aflatoxins B1 and M1 and aflatoxin B1-N7-guanine adduct. The study was conducted in 2017 on two groups of volunteers, the workers group, composed by personnel employed in an Italian feed plant (n = 32), and a control group (n = 29), composed by the administrative employees of the same feed plant; a total of 120 urine samples were collected and analysed. A screening method and a quantitative method with high-resolution mass spectrometry determination were developed and fully validated. Limits of detections were 0.8 and 1.5 pg/mLurine for aflatoxin B1 and M1, respectively. No quantitative determination was possible for the adduct aflatoxin B1-N7-guanine. Aflatoxin B1 and its adduct were not detected in the analysed samples, and aflatoxin M1, instead, was found in 14 samples (12%) within the range 1.9–10.5 pg/mLurine. Only one sample showed a value above the limit of quantification (10.5 pg/mLurine). The absence of a statistical difference between the mean values for workers and the control group which were compared suggests that in this specific setting, no professional exposure occurs. Furthermore, considering the very low level of aflatoxin M1 in the collected urine samples, the contribution from the diet to the overall exposure is to be considered negligible
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
Variations 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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