1,720,969 research outputs found
Alternaria toxins in wheat samples from experimental fields.
No full textAlternaria toxins in wheat samples from experimental field
Determinazione di Aflatossina e Ocratossina A in fluidi biologici da LC-HRMS
No full textLo sviluppo di nuovi metodi di analisi per le micotossine si è recentemente orientato verso un approccio multi-analita associato alla determinazione in spettrometria di massa. L’analisi dei biomarcatori, intesi come la tossina tal quale o i suoi metaboliti, rappresenta un campo di applicazione di interesse, in particolare quando la determinazione viene eseguita tramite la spettrometria di massa ad alta risoluzione. Il lavoro presenta lo sviluppo e la validazione di metodi per l’analisi in LC-HRMS di micotossine e loro metaboliti in campioni di urina e siero, nell’ambito di un progetto EFSA (BIODAF) sulla valutazione dell’esposizione professionale. In particolare, per le urine è stato testato un approccio dilute&shoot per l’analisi di AFB1, AFM1 e AFB1-N7-Guanina. I valori di LOD/LOQ sono stati successivamente abbassati includendo un passaggio di purificazione su colonnina di immunoaffinità. Il metodo per l’analisi dei sieri ha incluso l’AFB1, AFB1-Lisina e l’OTA. Durante il processo di validazione sono stati individuati il LOD e il LOQ, quest’ultimo è stato incluso nei livelli di concentrazione su cui è stata effettuata la validazione, inoltre la linearità è stata verificata nel campo di applicazione dei metodi. La giustezza e stata stimata, attraverso esperimenti di fortificazione, con il calcolo del recupero apparente. I valori ottenuti sono stati 101% e 98% per AFB1 and AFM1, nelle urine, e 55% e 61% per AFB1 e OTA, nel siero. La precisone è stata valutata attraverso il calcolo della deviazione standard relativa ottenuta dalle ripetizioni di analisi. I valori ottenuti sono stati 7% e 11% per AFB1 e AFM1, nelle urine, e 11% e 9% per AFB1 e OTA, nel siero. L’effetto sull’intensità del segnale dovuto alla presenza della matrice (SSE) è stato valutato tra l’ 82 e il 111% per le urine (metodo dilute&shoot) e tra l’82 e il 96% per AFB1 e OTA nel siero. I risultati ottenuti sono stati giudicati positivamente. Inoltre, l’utilizzo degli standard interni marcati per la quantificazione dei campioni rende questi metodi particolarmente idonei per la determinazione delle micotossine e dei loro metaboliti nei campioni di fluidi biologici caratterizzati da composizioni a volte anche molto diverse
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
Determination of deoxynivalenol biomarkers in italian urine samples
No full textDeoxynivalenol (DON) is a mycotoxin mainly produced by Fusarium graminearum that can contaminate cereals and cereal-based foodstuff. Urinary DON levels can be used as biomarker for exposure assessment purposes. This study assessed urinary DON concentrations in Italian volunteers recruited by age group, namely children, adolescents, adults, and the elderly. In addition, vulnerable groups, namely vegetarians and pregnant women, were included in the study. To determine the urinary DON, its glucuronide and de-epoxydated (DOM-1) forms, an indirect analytical approach was used, measuring free DON and total DON (as sum of free and glucuronides forms), before and after enzymatic treatment, respectively. Morning urine samples were collected on two consecutive days, from six different population groups, namely children, adolescent, adults, elderly, vegetarians and pregnant women. Total DON was measured in the 76% of the collected samples with the maximum incidences in children and adolescent age group. Urine samples from children and adolescent also showed the highest total DON levels, up to 17.0 ng/mgcreat. Pregnant women had the lowest positive samples per category (40% for day 1 and 43% for day 2, respectively), low mean levels of total DON (down to 2.84 ng/mgcreat) and median equal to 0 ng/mgcreat. Estimation of DON dietary intake reveals that 7.5% of the total population exceeds the TDI of 1 μg/kg bw/day set for DON, with children showing 40% of individuals surpassing this value (male, day 2)
Dietary exposure assessment of European population to mycotoxins: a review
No full textIn the area of food, risk assessment consists of four elements: hazard identification, hazard characterization, exposure assessment, and risk characterization. Exposure assessment and the other elements entail different sources of uncertainty and variability that can affect the reliability of the final output. Among the most relevant tools for exposure assessment studies, deterministic versus probabilistic, total diet versus duplicate studies, and food surveys versus the use of biomarkers in biological fluids constitute approaches most commonly used by researchers. In this chapter, the data available in the literature on assessment of the exposure of the European population to mycotoxins are shown. They reveal that specific groups such as infants and children are the most exposed because of an unfavorable ratio of intake to body weight. In addition, main pros and cons related to occurrence and consumption data are presented with particular emphasis on sampling error and the improper use or incomplete nature of both types of data
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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