1,721,027 research outputs found
Heterochromatin Bands and rDNA Sites Evolution in Polyploidization Events in Cynodon Rich. (Poaceae)
No full textCynodon is a genus with a wide distribution in tropical and subtropical areas. Ploidy levels in Cynodon range from diploid to hexaploid; hence, polyploidy is the most important driver of chromosome number variation in this genus. After polyploidization, structural rearrangements such as deletions, insertion, or duplications of DNA sequences frequently occur, allowing variation of chromosome morphology, size, and number. These events might result in a wide diversity of karyotypes, contributing to reproductive isolation, and consequently to speciation. In this study, we investigate the karyotype variation of Cynodon based on comparative cytogenetic analyses. We conducted chromosome counts, DNA quantification, CMA/DAPI double staining, and FISH mapping of 5S and 35S rDNA sites. Cytomolecular data were analyzed in a phylogenetic framework, in order to trace the evolutionary history of the karyotype variation considering polyploidy events in this group. Our results indicate that the most recent common ancestor of Cynodon had two 35S and 5S rDNA sites, two CMA bands, nine DAPI+ bands on the long arm, five DAPI+ bands on the short arm, and three DAPI+ bands in the pericentromeric region. During polyploidization events, there were losses and gains of heterochromatic sequences mainly on the short arms and centromeric regions
Reconstructing ancestral chromosome numbers and inflorescence features in Eleusininae (Poaceae: Chloridoideae: Cynodonteae)
No full textThe chromosome number in Poaceae has changed widely over 77 Myr of evolution and polyploidization. Chromosome number changes can suggest a high rate of diversification and evolutionary novelties, and such changes can contribute to speciation. Despite this, chromosome numbers alone do not allow the evolutionary history of a group to be traced. Combined phylogenetic and karyological analyses can clarify the evolutionary history of taxa and allow taxonomic relationships and hierarchical levels to be inferred. The subtribe Eleusininae is the largest of the subfamily Chloridoideae. This study aims to reconstruct their chromosome number evolution, for which ChromEvol 2.0 software was used. Haploid chromosome numbers of Eleusininae were retrieved from the literature, and a consensus phylogenetic tree of Eleusininae was reconstructed. It was possible to infer 41 events of chromosome rearrangements along the evolutionary history of Eleusininae, according to the probabilistic model used. Chromosome number evolution in Eleusininae was mainly influenced by polyploidy events. The ancestral basic chromosome number for Eleusininae was p=6, but the most recent common ancestor showed p2=10. In addition, some derived basic chromosome numbers, such as x=9, arose through dysploidy, whereas x=20 was generated via polyploidy
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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