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
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
Characterisation and evolutionary dynamics of ten novel Gammapapillomavirus types from South African penile swabs
Get PDFHuman papillomaviruses (HPVs) are genetically diverse, belonging to five distinct genera: Alpha, Beta, Gamma, Mu and Nu. We discovered ten novel Gammapapillomaviruses (Gamma-HPVs). Genomic characterisation and phylogenetic evaluation of the ten novel Gamma-HPV types were done: HPV211, HPV212, HPV213, HPV214, HPV215, HPV216, HPV219, HPV220, HPV221 and HPV222. These HPVs were previously identified in a study that was done on 218 penile samples (104 HIV negative and 114 HIV positive) using high throughput sequencing (Roche 454) of amplimers obtained using FAP59/64 primers which were designed to detect “cutaneous” or Beta- and Gamma-HPVs. Fifteen putative novel HPV types were identified from the short HPV L1 FAP fragments HPV211 (CT02, KY063000), HPV212 (CT03, KY063001), HPV213 (CT04, KY063002), HPV214 (CT06, KY063004), HPV215 (CT07, KY063005), HPV216 (CT12, KY063010), HPV219 (CT01, KY062999), HPV220 (CT08, KY063006), HPV221 (CT09, KY063007) and HPV222 (CT155, AY009886) with prevalences varying from 0.5% to 4.1% of men sampled. Multiple full genome clones for each novel type were generated through whole genome amplification, cloning and next generation sequencing. Complete genome sizes were: HPV211 (7253 bp), HPV212 (7208 bp), HPV213 (7096 bp), HPV214 (7357 bp), HPV215 (7186 bp), HPV216 (7233 bp), HPV219 (7108 bp), HPV220 (7381 bp), HPV221 (7326 bp) and HPV222 (7275 bp). Phylogenetically the novel Papillomaviruses (PVs) all clustered with Gamma-HPVs: HPV211 is most closely related to HPV168 (72% identity in the L1 nucleotide sequence) of the Gamma-8 species, HPV212 is most closely related to HPV144 (82.9%) of the Gamma-17 species, HPV213 is most closely related to HPV153 (71.8%) of the Gamma-13 species, HPV214 is most closely related to HPV103 (75.3%) of the Gamma-6 species, HPV215 and HPV216 are most closely related to HPV129 (76.8% and 79.2% respectively) of the Gamma-9 species. HPV219 is phylogenetically most closely related to HPV213 (87% identity in L1 gene) of the Gamma-13 species, HPV220 to HPV212 (72%) of Gamma-17, HPV221 to HPV142 (80%) of Gamma-10, HPV222 to HPV162 (73%) of Gamma-19. The novel HPV types demonstrated the classical genomic organisation of Gamma-HPVs, with seven open reading frames (ORFs) encoding five early (E1, E2, E4, E6 and E7) and two late (L1 and L2) proteins. Typical of Gamma-HPVs, the novel types all lacked the E5 ORF and HPV214 also lacked the E6 ORF. We further examined variation of the novel types in clinical specimens from which they were identified. All the clones of HPV211, HPV214, HPV216, HPV219 and HPV221 were identical and showed 100% pairwise identity. The clones of HPV213, HPV215, HPV212, HPV220 and HPV222 had several differences. Analysis of mismatches between the nine genomic clones of HPV212 showed a total of 67 mismatch positions that varied along the 7208 bp genome and all the clones were unique. Analysis of mismatches between the 10 genomic clones of HPV213 showed a total of 51 mismatch positions that varied along the 7096 bp genome and it had 5 unique clones. The 6 genomic clones of HPV215 showed a total of 50 mismatch positions along a 7186 bp genome and it had 3 identical and 3 different clones. HPV220 had 4 different genomic clones that showed 17 mismatch positions along a 7381 bp genome. The 5 different clones of HPV222 showed a total of 24 mismatch positions along the 7275 bp genome. Conserved domains observed among the novel types were the Zinc finger binding Domain and PDZ domains. A retinoblastoma binding protein (pRB) binding domain in the E7 protein was additionally identified in HPV214 and HPV222. PVs are thought to evolve slowly because they co-opt high-fidelity host cellular DNA polymerases for their replication. Despite extensive efforts to catalogue all the HPV species that infect humans, it is likely that many still remain undiscovered. We used the genome sequences of the ten novel viruses and related HPVs to analyse the evolutionary dynamics of these viruses at the whole genome and individual gene scales. We found statistically significant incongruences between the phylogenetic trees of different genes which imply gene-to-gene variation in the evolutionary processes underlying the diversification of Gamma-PVs. We were, however, only able to detect convincing evidence of a single recombination event which, on its own, cannot explain the observed incongruences between gene phylogenies. The divergence times of the last common ancestor (LCA) of the Alpha, Beta, Mu, Nu and Gamma genera was predicted to have existed between 49.7-58.5 million years ago before splitting into the five main lineages. The LCA of the presently sampled Gamma-PVs was predicted to have existed between 45.3 and 67.5 million years ago: approximately at the time when the simian and tarsier lineages of the primates diverged. The discovery, characterisation and classification of HPV211, HPV212, HPV213, HPV214, HPV215 HPV216, HPV219, HPV220, HPV221 and HPV222 add these novel types to the repertoire of the ever expanding Gamma-HPVs genus hence expanding our knowledge of these viruses
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
A study of the genital microbiotas of black South African women and men: associations with human papillomavirus and HIV infections
Get PDFPersistent genital infection with oncogenic or high-risk human papillomavirus (HPV) is causally associated with cervical cancer in women and some penile cancers in men. The role of the complex genital microbiota in HPV infection has not been extensively addressed. This study characterised the genital microbiotas of heterosexually-active Black South African women and men, predominantly of the Xhosa ethnicity, recruited from a community in Cape Town, South Africa. The association of the genital microbiotas with prevalent HPV, HIV, demographic, behavioural, and clinical characteristics of the participants was examined. In Chapter 2 the bacterial communities in cervicovaginal samples from 62 HIVseronegative South African women were profiled by Ion Torrent PGM sequencing of the V4 hypervariable region of the bacterial 16S rRNA gene (IT-V4 method). The cervicovaginal microbiotas (CVMs) were found to cluster into three distinct community state types (CSTs): Lactobacillus iners-dominated CVMs (CST I (38.7%, 24/62)), unclassified Lactobacillusdominated CVMs (CST II (4.8%, 3/62)), and diverse CVMs (CST III (56.5%, 35/62)) with an array of heterogeneous bacteria, predominantly the bacterial vaginosis (BV)-associated Gardnerella, Prevotella, Sneathia, and Shuttleworthia. The majority of the women had nonLactobacillus-dominated CVMs. Lactobacilli are recognised as protective against sexually transmitted infections. Among the Lactobacillus species detected in the women, L. iners was the most prevalent and abundant. This species is recognised as the least protective amongst the vaginal lactobacilli. Women in CST I were more likely to be on hormonal contraception compared to women in CST III (relative risk (RR): 2.6 [95% CI 1.3-5.3]; p=0.005). Further research is required to confirm this association and to determine the biological mechanism. Microbiome research methodologies are constantly improving and in Chapter 3 the performance of two bacterial 16S rRNA gene amplicon-based methodologies were compared. The CVMs of 19 women were characterised using the IT-V4 method (Chapter 2) and using the Illumina 16S rRNA metagenomics method (IM-V3/V4 method). The latter method involves sequencing the V3 and V4 hypervariable regions of the 16S rRNA gene on the Illumina MiSeq platform. The two methods showed a high degree of correlation (r=0.89, p3, p3, p3, p 2, p<0.05) Men with BV-negative female sexual partners (66.5% (157/236)) had higher relative abundances of Lactobacillus in their penile microbiotas than men with BV-positive female partners (p=0.007). Atopobium, Sneathia, and Saccharofermentans were significantly more prevalent in men with BV-positive female partners than men with BV-negative partners (p<0.020). The main limitations of our study include relatively small sample size of women, insufficient participant information such as host genetics, other STIs (e.g., herpes simplex virus) and abnormal vaginal flora (e.g., aerobic vaginitis), using a less sensitive method to diagnose BV in women, and inherent biases evident in any retrospective study. Moreover, we did not adjust for confounding factors in our analysis due to the small sample size. Despite the underscored limitations, our findings provide insight into the baseline genital microbiotas of the Black South African women and men. The associations identified in this cross-sectional study between specific microbiota members and HPV infection, particularly the association between Sneathia and HPV/high-risk HPV infection, identified in both women and men, are hypothesis-generating and warrant further investigation. The study forms a critical starting point for future longitudinal confirmatory association studies and studies examining these bacteria as potential biomarkers or risk factors for HPV infection
An Investigation into nonstructural proteins NS3 and NS3A of African Horsesickness virus
No full textDissertation (MSc (Genetics))--University of Pretoria, 2006.The aims of this investigation were to compare the nonstructural proteins, NS3 and NS3A, of African horse sickness virus (AHSV) and to further characterize the cytotoxic properties of these proteins. NS3 and NS3A are encoded from two in-phase overlapping reading frames on the smallest double-stranded (ds) RNS genome segment, segment 10 (S10) of AHSV. The proteins differ only with respect to the presence of an additional 10 or 11 amino acids, depending on the serotype, at the N-terminal of NS3. All known orbiviruses have been shown to encode two closely related proteins from S10. Sequence analysis of the N-terminal region of the NS3 proteins of the different serotypes of AHSV and various orbiviruses revealed that this region is not highly conserver. Both AHSV NS3 and NS3A are membrane-associated and cytotoxic to insect cells causing membrane permeabilisation and eventual cell death when expressed individually (Van Staden et al., 1995; Van Staden et al., 1998; Van Niekerk et al., 2001a). AHSV infection of Vero cells results in the synthesis of both proteins in equimolar amounts (Van Staden, 1993). The effect on the cytotoxic properties of these proteins when expressed together in insect cells was therefore investigated here. Whether co-expressed or expressed individually NS3 and NS3A caused a dramatic decrease in the viability of insect cells. The NS3 protein is therefore representative of the NS3 and NS3A proteins together in terms of its cytotoxic effect. The effect of the exogenous addition of NS3 on the membrane permeability of Vero cells was also investigated. The NS3 protein was found to cause a rapid increase in the membrane permeability of Vero cells. The cytotoxic properties of NS3 appear therefore not to be limited to their endogenous effects on insect cells. The AHSV-3 NS3 and NS3A proteins were expressed as histidine tagged recombinants in the baculovirus expression system, to allow for the purification of large quantities of protein for functional and comparative studies. The resulting NS3 histidine fusion product, however, displayed a decrease in solubility, probably as a result of incorrect folding due to the presence of this histidine tag extension at the N-terminus of the protein. To produce antibodies that detect NS32, and not NS3A, in AHSV infected cells, the N-terminal region unique to AHSV-3 NS3 was displayed on the surface of the AHSV core protein, VPO7. The chimeric protein VP7-NS3 displayed the same structural characteristics as the wild type VP7 protein, aggregating into highly insoluble crystals. Antiserum was prepared against purified VP7-NS3 and analysed in terms of its ability to recognize denatured and non-denatured AHSV-3 NS3. Although the antiserum was shown to contain antibodies directed against VP7 epitopes no immune reaction with NS3 was observed. The use of alternate sites on the surface region of VP7 for the display of such a small peptide needs to be investigated. Although no functional differences between NS3 and NS3A were identified in this investigation, the finding that NS3 causes membrane permeability of damage to Vero cells represents the first indication that this AHSV protein causes extra cellular membrane damage in mammalian cells. Many viral membrane damaging proteins or viroporins are thought to contribute significantly to the severity of virus-induced pathogenesis. The mechanism of membrane damage and the contribution of the membrane damaging properties of NS3 to AHSV-induced pathogenesis needs to be investigatedGeneticsunrestricte
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