1,720,971 research outputs found
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
Germ cell fate determination: Cloning and characterization of <italic>fog-3</italic> and its homologs in <italic>Caenorhabditis</italic>.
No full textIn C. elegans, the choice of sex is determined by a cascade of sex determination genes. Genetic studies indicate that fog-3 acts at the end of this cascade, and that fog-3 might directly determine male sexual fate in the germ line. Studies of fog-3 in this thesis show that FOG-3 is a nematode homolog of the Tob family of proteins, which have been suggested to suppress proliferation or promote differentiation. The domain that BTG1 and BTG2 share with FOG-3 interacts with a transcriptional regulatory complex that has been conserved in all eukaryotes. Finally, analysis of mutations shows that this domain is essential for fog-3 to function. Thus, one possibility is that FOG-3 controls transcription of genes required for germ cells to initiate spermatogenesis rather than oogenesis. How is FOG-3 activity regulated? Several lines of evidence suggest fog-3 is regulated by tra-1. First, Northern analyses and RT-PCR experiments indicate that expression of fog-3 mRNA is controlled by tra-1. Second, studies of fem;tra-1 double mutants show that this control could be direct. Third, the fog-3 promoter contains multiple sites that bind TRA-1A in gel shift assays, and mutations in these sites alter the activity of fog-3 in vivo. These results establish fog-3 as one of the first known targets of transcriptional regulation by TRA-1A. Furthermore, we show that tra-1 controls a terminal regulator of sexual fate in germ cells, just as it is thought to do in the soma. To learn if the function of fog-3 has been conserved during evolution, we cloned its homologs from C. briggsae and C. remanei. Both BTF and TF are highly conserved in Cb-FOG-3 and Cr-FOG-3, suggesting that these domains are important for fog-3 to function. Furthermore, one additional region that is unique to the FOG-3 proteins is also highly conserved. The phenotypes of Cb-fog-3 and Cr-fog-3 RNAi animals suggest that fog-3 is required to promote male germ cell fates in all three nematode species. Finally, there are TRA-1A binding sites upstream of the coding regions of Cb-fog-3 and Cr-fog-3. This suggests that the regulation of fog-3 by TRA-1A has also been conserved during evolution.PhDBiological SciencesGeneticsMolecular biologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/132318/2/9963754.pd
Hermaphrodite or female: Rapid evolution of mating systems in the genus <italic>Caenorhabditis</italic>.
No full textThere are two different mating systems in the genus Caenorhabditis . In some species, like C. elegans and C. briggsae, XX animals become self-fertile hermaphrodites, whereas in other species XX animals become true females. How have these mating systems evolved? Since the major difference between hermaphrodites and females is that the former produce sperm during larval development, we are studying how the sexual fate of germ cells is controlled in each species. In C. elegans, fog-1 and fog-3 act at the end of the sex-determination pathway in the germ line, and appears to directly control germ cell fates. Mutations in upstream genes that cause increased expression of fog-1 and fog-3 also cause all germ cells to become sperm, and those that cause lower expression of fog-1 and fog-3 cause all germ cells to become oocytes. We cloned the homologs of fog-1 and fog-3 from C. briggsae and C. remanei. Although the sequences of these genes are evolving rapidly, we found that each is required for germ cells to become sperm, just as in C. elegans. Furthermore, their expression is controlled by tra-1 and upstream sex-determination genes in each species, and the expression of fog-3 is always correlated with spermatogenesis. Thus, we propose that mutations in upstream sex-determination genes that alter fog-3 expression might be sufficient to cause nematodes to switch mating systems. To learn if changes in mating systems had occurred frequently, we performed phylogenetic analyses of six caenorhabditids, using the sequences of FOG-3 and four CPEB proteins from each species. Our results show that C. elegans and C. briggsae---the two hermaphroditic species---are not sister taxa, which indicates that mating systems must have changed more than once during caenorhabditid evolution. During the course of cloning the CPEB and FOG genes, we determined their genomic sequences, and used them to analyze changes in intron/exon structure during evolution. We observed a very high rate of intron loss for this genus, and found that these losses were much more common than the insertion of new introns. Statistical analyses of these events constrain models of how intron losses occur.PhDBiological SciencesGeneticsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/123806/2/3106031.pd
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
Cell fate in the <italic>C. elegans</italic> germline is regulated by the CPEB protein FOG -1.
No full textIn C. elegans, sexual identity is determined by a cascade of sex-determination genes. Genetic epistasis tests indicate that fog-1 acts at the end of this cascade in the germ line, and might directly control germ cell fates. I cloned the fog-1 gene and found that it encodes an RNA-binding protein of the Cytoplasmic Polyadenylation Element Binding (CPEB) protein family. These proteins have been shown to regulate the translation of target messenger RNAs. Analyses of mutations show that the conserved RNA binding domains are essential for FOG-1 activity, since all known fog-1 missense mutations are clustered in these domains. Furthermore, biochemical experiments show that FLAG-tagged FOG-1 binds to its own 3'-UTR in vitro. The interaction between FOG-1 and its 3' UTR seems to be specific, since mutant fog-1 3'-UTR competes poorly with the wild-type fog-1 3' -UTR for interaction with FOG-1. Based on those results, we hypothesize that FOG-1 might control germ cell fates by regulating the translation of its own and other messenger RNAs. FOG-1 is the first CPEB proteins known to be involved in spermatogenesis. To learn how FOG-1 acquired this activity, I cloned CPEB genes from related species of nematodes. I found that all of these species have four CPEB genes, and that the origin of these four types of CPEB proteins predates this group of nematodes. Furthermore, the function of FOG-1 has been conserved during nematode evolution. Finally, each FOG-1 contains a large, conserved insertion in one of the RNA-binding domains. Since the other nematode CPEB proteins groups also have their own unique insertions, these alterations might represent a general mechanism for altering CPEB protein function.PhDBiological SciencesMolecular biologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/132598/2/9977183.pd
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