1,720,961 research outputs found
Image analysis and automatic classification of transformed foci
No full textCarcinogenesis is a multi-step process involving genetic
alterations and non-genotoxic mechanisms. The in vitro cell
transformation assay allows the monitoring of the neoplastic
phenotype by foci formation in suitable cells (e.g. C3H10T1/2
mouse embryo fibroblasts) showing aberrant morphology of
massive build-up, polar and multi-layered densely stained
cells. The classification of transformed foci in C3H cells relies
on light microscopy scoring by a trained human expert
based on standard rules. This procedure is time-consuming
and prone, in some cases, to subjectivity, thereby leading
to possible over- or under-estimation of the carcinogenic
potential of tested compounds. Herewith we describe the in
vitro neoplastic transformation induced by B[a]P and CdCl 2 ,
and the development of a foci classifier based on image analysis
and statistical classification. The image analysis system,
which relies on ‘spectrum enhancement’, is quantitative
and extracts descriptors of foci texture and structure. The
statistical classification method is based on the Random Forest
algorithm. We obtained a classifier trained by using expert’s
supervision with a 20% classification error. The proposed
method could serve as a basis to automate the in vitro cell
transformation assay
Image classifiers for the cell transformation assay: a progress report
No full textThe human carcinogenicity evaluation of chemicals has a great impact on public health. In vitro methods, such as the cell transformation assay (CTA), allow for a fast and reliable assessment of the carcinogenic potential of a chemical compound in comparison with the standard two-year bioassay. The scoring and classification of foci in selected cell lines is performed, after staining, by light microscopy. Foci can be separated into three classes: type I, which are scored as non-transformed, and types II and III that are considered to include fully transformed foci. However, in a number of cases, even an expert is uncertain about the attribution of a focus to a given class, due to its mixed or intermediate nature. Here, we suggest a simple approach to classifying mixed or intermediate foci by exploiting the quantitative information available from images, which is captured by statistical descriptors. A quantitative index is proposed, to describe the degree of dissimilarity of mixed and intermediate images to the three well-distinguished classes
Image analysis applied to Cell Transformation Assay to advance carcinogenicity testing : morphology evaluation of transformed foci and mitochondria
No full textDigital image analysis has demonstrated to be a very promising tool to promote toxicity testing and advancements in the comprehension of olecular mechanisms underlying toxicity outcomes. Cell and tissue imaging allow quantitative detection and measurement of cellular structures and components including organelles, and is supported by microscopes, digitized cameras, and image analysis algorithms (Xu, 2015). We developed methods of image analysis to improve carcinogenicity testing, as the phenotype can be informative of many underlying mechanisms and pathways of in vitro transformation. We foster the adoption of an integrated approach, where functional assays can be coupled with morphology studies in order to understand mechanisms of toxicity. Our work supports the idea that form follows function
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
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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