1,720,975 research outputs found
Genotoxicity in risk assessment : is it time to use a threshold approach?
No full textSubstances that act via a genotoxic mechanism are considered to follow a low dose linear relationship with the absence of a threshold. The discussion on the existence of a threshold for genotoxic (mutagenic and clastogenic) compounds appears sometimes more an academic exercise than of practical use in public health. However, pragmatically, determination of the PoD, i.e. the dose/concentration from which we derive acceptable exposure levels, should be the goal. This will include appropriate dose response data analysis, with statistically defensible methods and use of mechanistic data, and application of adequate uncertainty factors. The best and full use of the quantitative information can be used to analyse dose–response data, and dismiss the binary classification scheme for use in risk assessment and management. Certainly, in areas such as the relationship between the genotoxic and the carcinogenic effect, the appropriate BenchMark Response (BMR) to be used, the relation between effects in target tissues vs those observed in surrogate tissues, and the uncertainty of our measurements there is a need of more solid data. While the simple binary classification scheme can be of some help for screening and prioritization of substances that need further scrutiny, it is not an adequate tool to be used for risk management decisions. The final step of the assessment for guiding management decisions should be quantitative to the extent possible. Accepting the threshold approach on which to base the risk management decisions has significant beneficial economic and societal impact and implications
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
Moderate alcohol consumption during pregnancy increases potency of two different drugs (the antifungal fluconazole and the antiepileptic valproate) in inducing craniofacial defects: prediction by the in vitro rat whole embryo culture
Get PDFThe prenatal exposure to ethanol (Eth), fluconazole (FLUCO) and sodium valproate (VPA) is related to effects on development, producing characteristic syndromic pictures. Among embryotoxic effects described for the three molecules, the alteration on craniofacial morphogenesis is a common feature in humans and animal models, including rodent embryos developed in vitro. The aim of the present work is to evaluate the developmental effects of low Eth serum concentration (17 mM, corresponding to the legal limit to drive in UK, USA, Canada, and many other countries) in mixture with increasing realistic concentrations of the antifungal drug FLUCO (62.5–500 μM) or with increasing realistic concentrations of the antiepileptic drug VPA (31.25–250 μM). Groups exposed to Eth alone (17–127.5 mM), FLUCO alone (62.5–500 μM) or VPA alone (31.25–750 μM) were also included. The chosen alternative animal model was the post-implantation rat whole embryo culture (WEC). E9.5 embryos were exposed in vitro to the test molecules during the whole test period (48 h, corresponding to the developmental stages characteristics of any vertebrate, for human embryos post-fertilization days 23–31). Data were statistically analyzed and processed for modelling applying the benchmark dose (BMD) and relative potency factor (RPF) approaches. Concentration-related effects on facial outcomes were observed in all experimental groups, with a significant enhancement in the groups co-exposed with Eth in comparison to the single exposures. Data obtained by the present work suggest an additional alert for the assumption of even low levels of alcohol in pregnant women during FLUCO or VPA therapy
Relative potency ranking of azoles altering craniofacial morphogenesis in rats : an in vitro data modelling approach
Get PDFFacial malformations represent one of the most frequent abnormality in humans. The adverse outcome pathway involved in facial defects seems to be related to retinoic acid (RA) pathway imbalance. Environmental agents inducing craniofacial malformations in experimental models include pesticides (especially azole fungicides). By using the in vitro alternative method postimplantation rat whole embryo culture (WEC), we evaluated the intrinsic embryotoxic activity of some azole antifungals (cyproconazole, CYPRO; triadimefon, FON; flusilazole, FLUSI; and prochloraz, PCZ), in comparison to RA. All the tested molecules induced in a dose-related manner specific defects of the craniofacial structures (fused branchial arches), similar to those induced by RA. Collected data were modelled using PROAST 65.5 software to characterise the relative potency factors (RPFs) versus RA. In comparison to RA, all the evaluated azoles were less potent, showing among them a similar potency. Our data suggest a possible azole-related RA signalling perturbation to be further investigated. Moreover, the present results indicate the approach used in this work to be an interesting tool applicable to the hazard evaluation of novel compounds or the assessment of combined exposure to azoles or other dismorphogens
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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