1,721,010 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
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
Application of the Neutral Indel Model to genome sequences for diverse metazoans
No full textThe Neutral Indel Model is able to predict accurately the distribution of indel events in alignments of neutrally evolving genomic sequence. Here, I apply this model to a diverse range of metazoan species pairs, to a number of ends. First, I apply the Neutral Indel Model to alignments of genome sequences for species within the mammalian clade in order to estimate the quantities of functional DNA shared between species pairs. I demonstrate that as the evolutionary divergence between species pairs increases, estimates of functional sequence drop off dramatically. This pattern is not replicated in extensive simulations of genome sequence alignments, suggesting that functional (and mostly non-coding) sequence is turning over at a rapid rate. I also estimate that between 200 and 300 Mb (6.5-10%) of the human genome is under evolutionary constraint, a considerably higher quantity of sequence than has been estimated by previous whole genome analyses. Second, extending my analyses to consider more diverse metazoan species, I provide estimates for functional bases within organisms’ genomes that appear to mirror our conceptions of organismal complexity. Thirdly, I develop the Neutral Indel Model as a method for assessing genome sequence quality, by quantifying indel errors within alignments of closely related (ds < 0.1) species pairs. Applying this method to six primate genome sequence assemblies, I demonstrate that the frequency of indel error events per base varies up to six-fold. Further to this, I show that second generation sequencing technologies can be used to create high quality genome sequence assemblies and to ameliorate errors in pre-existing assemblies. Finally, I analyse patterns of indel mutations in primate transposable elements and show that indels are not randomly distributed within these sequences due to regularly spaced homo-nucleotide motifs
Next generation sequencing in disease-relevant tissues
Get PDFStudies of RNA and the transcriptome are of great importance in providing functional information and unravelling the genetic mechanisms that underlie complex disorders and diseases. With the vast majority of complex disease-associated variants falling outside protein-coding regions of the genome, it is likely that variations in gene expression regulation will be essential to understanding disease aetiology. Information on RNA quantity and splicing isoforms is therefore likely to be crucial for understanding complex pathologies of deleterious genetic variation. The advent of next generation sequencing has allowed the development of an assortment of technologies for interrogating aspects of the genome, one of which is high-throughput RNA sequencing (RNA-Seq). This technology allows rapid, relatively cheap, and accurate quantification of transcripts at a genome-wide scale. By providing a greater number of advantages and fewer caveats than alternative methods of transcriptome quantification, RNA-Seq is a disruptive technology that is likely to supersede most others. Throughout this thesis, I have sought to demonstrate how these advantages assist in revealing significant and novel developmental, noncoding, coding, and alternative isoform information of relevance to disorders and diseases. I take advantage of methods that utilize the truly genome-wide coverage of RNA-Seq, that quantify large numbers of transcripts, and that interrogate novel splicing events. More specifically, I present (i) the identification of novel biomarkers of the various placode-derived vertebrate cranial nerves, (ii) differential gene networks which highlight the genetics of autism intellectual disability co-morbidity, and (iii) differential gene expression underlying a form of severe influenza susceptibility. In addition to these studies, this thesis presents an R package for RNA-Seq time-series experiments, including functionality for efficient model-based clustering, and the integration of gene ontology information for cluster number selection and for subsequent profiling. Overall, this thesis demonstrates how RNA-Seq is a powerful tool for understanding disease aetiology
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
Investigating liver regeneration using single cell RNA sequencing
Get PDFLiver disease causes over 2 million deaths world-wide each year and is the most common disease related deaths in adults aged between 35-49 years old in the UK. While the liver has a large capacity to regenerate this is overwhelmed during chronic injury. Currently there is no drug-based treatment for end stage liver disease, with transplantation the only option. This is problematic as only around 10% of the global transplantation needs are met and urgent new therapeutics are required to tackling this highly prevalent disease. Despite decades of research elucidating the mechanisms behind the liver’s natural capacity to regenerate, there has not yet been a therapeutic agent approved. The prominent feature of liver regeneration is the replication of mature hepatocytes. Research has assumed homogeneity in function among the hepatocyte population during regeneration, however recent studies have shown that there is a more heterogeneous response. More work is required to understand the complex nature of this process at a higher resolution to unpick any heterogeneity and discover any further regenerative signals. Therefore, this project aimed to use a single cell RNA sequencing approach to identify any potentially novel heterogeneous populations of hepatocytes during liver regeneration and further identify any key signalling molecules.
Replicating and non-replicating hepatocytes were sorted from a partial hepatectomies FUCCI2a mouse model which reports G1 cells with a mCherry signal and S/G2/M cells with a mVenus signal. Hepatocytes were sorted directly into 384 well plates for single cell sequencing. Unsupervised cluster was performed to identify several populations of hepatocytes. Non-replicating cells split into cluster denoting there spacial location in the liver lobule. This was identified through the gradient of expression of zonal marker genes. While no novel heterogeneous cluster of replicating hepatocytes were found, several novel signalling molecules such as Il33, Il15, Dll1, Cklf, and Bmp7, were identified to be expressed only by replicating hepatocytes. Furthermore, a population of “primed” mCherry positive hepatocytes appeared to express
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several cell cycle marker genes. This population could represent a population of cells captured just before entry into S phase or a priming action of hepatocytes to prepare for cell cycle entry, awaiting an appropriate initiating signal. Interesting this population showed high expression for a circadian rhythm associated gene Timeless. Replication during partial hepatectomy is believed to be highly synchronous and Timeless may be the protein that controls the timing of replication during the model. Further studies of these genes are required to understand their function and importance in liver regeneration. In conclusion, the work demonstrated within this thesis highlights the need to study liver regeneration using high resolution techniques such as single cell RNA sequencing
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