1,721,050 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
Genetic modification of maize by introduction of antifungal genes to confer resistance to Fusarium Verticillioides
Get PDFDissertation (MSc)--University of Pretoria, 2004.Please read the abstract in the dissertationPlant Scienceunrestricte
Comparing a pathogenicity effector gene family from two cercospora species by agroinfiltration into tobacco
No full textDissertation (MSc (Biotechnology))--University of Pretoria, 2023.Cercospora zeina is the causal agent of grey leaf spot (GLS) of maize, which causes
devastating crop yield losses. The fungus secretes molecules termed effectors to overcome
host defences, obtain nutrients from the host and negatively affect the host. In this study, two
effectors in C. zeina and their orthologs from Cercospora zeae-maydis were identified as good
candidates to study based on in silico analyses. This included analyses by EffectorP 3.0,
Localizer 1.0, ApoplastP 1.0 SignalP 6.0. The two candidate effectors in C. zeina were named
CzCSEP4 and CzCSEP20, and in C. zeae-maydis termed CzmCSEP4 (89% identity to
CzCSEP4, on the protein level) and CzmCSEP20 (94% identity to CzCSEP20, on the protein
level). These genes were expected to cause a hypersensitive response in Nicotiana
benthamiana in the form of cell death. The genes were amplified from C. zeina or from C.
zeae-maydis cDNA and their native signal peptides were replaced with an apoplastic-specific
signal peptide. These effectors were then cloned into a binary vector system, transformed into
Agrobacteria, and infiltrated into N. benthamiana. In N. benthamiana the positive control of
INF1 (Phytophthora infestans) showed necrosis, whereas the two C. zeina candidate effectors
did not (p>0.05, t-test). The effectors were demonstrated to have structural similarities to the
Fulvia fulva Ecp2 effector’s Hce2 (Homologs of C. fulvum Ecp2) domain. Effectors containing
this domain were able to elicit a hypersensitive response in several tobacco species, including
N. tabacum, and could not elicit a response in N. benthamiana. These genes were then tested
in N. tabacum and showed a hypersensitive response in the infiltrated areas that was
significantly different to the Agrobacterium only control (p<0.05, t-test). In conclusion, these
genes can be termed secreted effector proteins, thereby proving that these genes are likely to
form part of an effector gene family and may play a role in promoting pathogenicity of the fungi
in the host.NRFPlant ScienceMSc (Biotechnology)RestrictedFaculty of Natural and Agricultural Science
SSHscreen and SSHdb : software for microarray-based screening and sequence management of cDNA libraries
Get PDFDissertation (MSc)--University of Pretoria, 2010.A pipeline was developed for the quantitative screening and sequence management of clones from suppression subtractive hybridization (SSH) cDNA libraries. The pipeline is particularly useful for gene discovery in non-sequenced organisms, and was illustrated with SSH library data from pearl millet (Pennisetum glaucum) and cowpea (Vigna unguiculata) and Arabidopsis (Arabidopsis thaliana) ecotype Kil-0. The objective of each library was to identify stress-response genes. cDNA microarrays provide a high-throughput screening method. Accordingly, these SSH libraries were amplified by PCR and spotted onto glass microarray slides. Subtracted and un-subtracted cDNA samples, that were used to construct the SSH libraries were prepared as Cy3- and Cy5-labeled targets and hybridized to the microarrays. The R package SSHscreen version 2.0.0, available from http://microarray.up.ac.za/SSHscreen/, was developed to analyze the resulting microarray data using limma (linear models for microarray data) functions. Commonly, loess normalization is used for within-slide normalization, however this is based on the assumption that most of the genes on the array are not differentially expressed. This is legitimate for most whole genome microarray experiments, however it is not appropriate when the array is constructed from an SSH library which is enriched for differentially expressed genes. Therefore, control spot-based normalization was used in the SSHscreen analysis. Empirical Bayes methods were employed to calculate the moderated t-statistic using functions from the limma package. This procedure in effect borrows information from the ensemble of genes to aid with inference about individual genes, taking advantage of the parallel structure whereby the same model is fitted to the data for each gene. In the Arabidopsis, pearl millet and cowpea forward libraries, 18%, 58% and 58% of the clones were identified as significantly up-regulated (adjusted p-value < 0.05) and in the reverse libraries, 18%, 30% and 28% significantly down-regulated, respectively. SSHscreen analysis was used to assist in selection of clones for sequencing. The SSHscreen data output (ranked gene lists in terms of differential expression), as well as the selected sequences in FASTA format were uploaded to SSHdb. For the Arabidopsis library, 114 out of the 262 sequenced clones (55%) were identified as unique/non-redundant; and for the pearl millet and cowpea libraries respectively, 37% and 33% of the sequenced clones were unique. SSHdb was developed as a web-based tool for sequence management and annotation of clones in SSH libraries and can freely be accessed at http://sshdb.bi.up.ac.za. BLAST analysis that was carried out when sequences were uploaded to SSHdb was used to combine clones with the same sequence into redundant partner groups, as well as identify putative annotations for each group. Individual clones from the abovementioned SSH libraries were selected and an independent technique, quantitative PCR, was used to validate the microarray/SSHscreen results. The pipeline was applied successfully to Arabidopsis, pearl millet and cowpea SSH cDNA libraries. Interesting genes in each case were identified for further study. CopyrightBiochemistryunrestricte
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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