1,720,971 research outputs found
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
Functional analysis of Xist-mediated silencing
Get PDFThe lncRNA Xist is the master regulator of X chromosome inactivation in female mammals. Its mono-allelic expression triggers a cascade of well characterised events leading to the stable silencing of the X chromosome. However, how Xist coordinates these events is still unclear. We developed a system to dissect Xist function by making a library of deletions of Xist cDNA. The cDNAs were then stably transfected into a male ES cell line under an inducible promoter. The parent cell line was derived from an interspecific cross between different mouse strains, allowing subsequent allele-specific analysis based on a previously described set of strain-specific SNPs. This approach allowed full and partial loss of silencing activity to be discriminated by isolating nascent transcripts upon prolonged Xist expression, and using them to make libraries for high-throughput sequencing. It was therefore possible to map regions of Xist required for specific functions, notably gene silencing and recruitment of Polycomb repressor proteins. Using this approach, the B-repeats were identified as the segment of the RNA crucial for de novo recruitment of both PRC1 and PRC2 Polycomb complexes, whereas the A-repeats were confirmed to be essential for Xist-mediated early silencing of genes. To complement these analyses, an in vitro assembly system was set-up to study the direct interaction between key regions of Xist RNA and defined nuclear proteins at the biochemical/proteomic level, obtaining a comprehensive list of functional candidates. Interestingly, the nuclear matrix protein hnRNP-K was found among the factors significantly enriched over the segment of Xist previously identified as essential for Polycomb recruitment. We thus investigated the functional role of hnRNP-K in mediating the interaction between Xist and Polycomb with a number of in vivo and in vitro assays, and found that hnRNP-K is required to mediate contact between PRC1 and Xist through its KI domain
Genetic Mapping and Characterization of a piRNA Mutant Library
No full textHistorically, several studies aimed to better understand the genetic regulation by small RNAs, have used C.elegans as a model organism. From the pioneering work on the regulation of lin-14 by lin-4, to the elucidation of the role of dsRNA in the so-called RNAi pathway, the nematode C.elegans has been regarded as a powerful tool to investigate different aspects of small RNA pathways.
In this work, an in vivo assay has been used to characterize a novel small RNA pathway, the Piwi/piRNA pathway in C.elegans.
The Piwi/piRNA pathway plays crucial roles during germline development and gametogenesis of many metazoan species, from germline determination and germline stem cell maintenance, to meiosis and spermiogenesis. Its function in all these processes lies in protecting the integrity of the genome from parasite nucleic acids, namely from transposons.
However, little is known about how the final biological function of the pathway is achieved: recent evidences support the hypothesis of a mechanism which involves both a post-trascriptional regulation (partially obtained by the activation of a distinct endo-siRNA pathway) and an epigenetic/co-transcriptional regulation.
A clearer view of this pathway will significantly advance our understanding of complex gene regulation strategies.
Previously, using a forward genetic screen, a large number of mutant alleles for genes involved in this pathway have been isolated. The aim of this study was to investigate the identity of those genes with high-throughput sequencing and linkage analysis, as well as by complementation tests. Finally, the involvement of each screened allele in the pathway was assessed through specific assays (chromosome non-disjunction assays, RNAi against a germ line specific gene, qRT-PCR for Tc3 expression).
Taken together with previous findings in the lab, these data enable us to provide a preliminary model for the general structure of the Piwi/piRNA pathway in C.elegans, pointing out its overlapping with the endogenous RNAi pathway, based on the activity of 22G endo-siRNAs
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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