1,721,018 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
The genomic and phenotypic characterization of phage-like plasmids and their ability to horizontally transfer antibiotic and heavy metal resistance genes to bacteria of foodborne importance
No full textAntibiotic resistance (AR) is emerging as a major public health problem with global implications. Each year, approximately 700,000 deaths worldwide are attributed to AR, and this number is predicted to rise to 10 million by 2050. Phage-like plasmids (PLPs) are a novel MGE that are part phage and part plasmid, and exist extrachromosomally within bacterial cells. Phage-like Plasmids are emerging as an important contributor to the spread of antibiotic resistance, because they harbour ARGs and/or heavy metal resistance (HMR) genes, and may have the potential to perform HGT by phage-mediated mechanisms, such as transduction, or plasmid-mediated mechanisms, such as transformation and conjugation. The objective of this study was to develop a better understanding of PLP genomic structure and biology, by focusing on two main objectives including genomic characterization of PLPs to determine their taxonomic structure and the types of ARGs and HMR genes that they carry, and phenotypic analysis of the potential of PLPs to horizontally transfer ARGs and HMR genes by transduction, transformation, and conjugation in order to determine whether they can confer resistance to antibiotics and heavy metals. A total of 57 PLPs (18 reported in the scientific literature, 31 PLP genome sequences identified within Genbank, and 8 PLPs that were isolated from bacterial strains of bovine and food origin) were characterized in this study. Genomic analysis revealed that 29% of the PLPs carried ARGs that are known to confer AR resistance to β-lactams, carbapenems, colistin, and aminoglycosides, and that 10% of the PLPs carried genes that have been associated with resistance to either mercury or tellurite. Additionally, the results from this genomic analysis suggested that 54 of 57 PLPs (93%) had nucleotide sequence identity to the Siphophage SSU5 or the prototypical PLP P1, and, therefore, could be classified into two distinct lineages, the SSU5-like and P1-like lineages. The SSU5-like PLP AnCo1 (encoding CTX-M-15), P1-like PLP SJ1 (encoding a mercury resistance operon), and P1-like PLP MA725 (encoding terB) were successfully transduced. PLP SJ1 was capable of infecting 18 different strains, including 2 commensal (lab) E. coli strains, 4 E. coli O157 strains, and 12 Salmonella strains, suggesting that this PLP may have a broad host range. Phage-like-Plasmids were also found to be capable of HGT through plasmid-mediated mechanisms, as demonstrated by the fact that the PLPs AnCo1, SJ1, and MA725 were successfully transformed to E. coli DH10B. Furthermore, while the PLPs lack genes necessary for conjugation, AnCo1 and SJ1 were successfully conjugated to E. coli J53 in the presence of the helper plasmid pRK2013. Phenotypic characterization of the ability of the PLPs to confer antibiotic and heavy metal resistance was conducted through minimum inhibitory concentration (MIC) experiments that demonstrated that, regardless of the HGT mechanism, individual PLPs conferred the same levels of resistance to their bacterial hosts. The PLPs AnCo1 and SJ1 conferred 3 mg/ml of resistance to cefotaxime and 50 μg/ml to mercury chloride, respectively. Of note, it was demonstrated for the first time that terB harboured by PLP MA725 conferred 40 μg/ml of resistance to potassium tellurite and conferred cross-resistance (10 μg/ml) to colistin sulphate, which is of clinical significance, as colistin is considered to be an antibiotic of last resort. Phage-like plasmids represent a versatile MGE, as they can mobilize ARGs and HMR genes via all 3 mechanisms of HGT. Taken together, the results of this study highlight the contribution of PLPs to the dissemination of AR within the agricultural and clinical environments.La résistance aux antibiotiques (AR) est reconnue comme un problème majeur de santé publique. Chaque année, environ 700 000 décès dans le monde sont attribués à l'AR, et ce nombre devrait atteindre 10 millions d'ici 2050. Les plasmides de type phage (PLP) sont un nouveau MGE composé à la fois de phage et de plasmide et existent de manière extrachromosomique au sein des cellules bactériennes. Les plasmides de type phage sont en train de devenir un contributeur important dans la propagation de la résistance aux antibiotiques, car ils contiennent des ARG et/ou des gènes de résistance aux métaux lourds (HMRs), et peuvent potentiellement utiliser la HGT grâce aux mécanismes propres au phage, tels que la transduction ou des mécanismes propres aux plasmides, tels que la transformation et la conjugaison. L'objectif de cette étude était d'acquérir une meilleure compréhension de la structure génomique et de la biologie des PLPs en se concentrant sur deux objectifs principaux : (1) la caractérisation génomique des PLPs pour déterminer leur structure taxonomique et les types de ARGs et gènes HMRs qu'ils portent et (2) l'analyse phénotypique de ces structures incluant le potentiel des PLPs à transférer horizontalement les ARGs et les gènes HMRs par transduction, transformation et conjugaison et ainsi déterminer si les PLPs peuvent ou non conférer une résistance aux antibiotiques et aux métaux lourds .Au total, 57 PLPs (18 publiés dans la littérature scientifique, 31 séquences de génome de PLP identifiées au sein de Genbank et 8 PLP isolés de souches bactériennes d'origine bovine et alimentaire) ont été caractérisés dans cette étude. L'analyse génomique a révélé que 29% des PLPs portaient des ARGs connus capable de conférer la résistance aux antibiotiques β-lactames, aux carbapénèmes, à la colistine et aux aminoglycosides. De plus, 10% des PLPs portaient des gènes HMRs connus pour conférer la résistance au mercure ou à la tellurite. En outre, les résultats de cette analyse génomique suggèrent que 54 PLP sur 57 (93%) avaient une identité de séquence nucléotidique avec le Siphophage SSU5 ou le PLP prototype P1 et pouvaient donc être classés en deux lignées distinctes, le type SSU5 et le type P1. Le PLP AnCo1 de type SSU5 (codant pour CTX-M-15), le PLP SJ1 de type P1 (codant pour un opéron de résistance au mercure) et le PLP MA725 de type P1 (codant pour terB) ont été transférés par transduction. PLP SJ1 était capable d'infecter 18 souches différentes, dont 2 souches de E. coli commensales (de laboratoire), 4 souches de E. coli O157 et 12 souches de Salmonella. Les plasmides de type phage se sont également avérés capables de transféré horizontalement les gènes par les mécanismes propres par les plasmides, comme le démontre le fait que les PLPs AnCo1, SJ1 et MA725 ont été transformées avec succès en E. coli DH10B et conjugé à E. coli J53 en présence du plasmide auxiliaire pRK2013. La caractérisation phénotypique de la capacité des PLPs à conférer une résistance aux antibiotiques et aux métaux lourds a été réalisée par des d'expériences de concentration minimale inhibitrice (CMI). Les PLPs AnCo1 et SJ1 ont conféré 3 mg/ml de résistance au céfotaxime et 50 µg/ml au chlorure de mercure, respectivement. De même, il a été démontré pour la première fois que le gène terB porté par le PLP MA725 conférait 40 μg/ml de résistance au tellurite de potassium et une résistance croisée (10 µg/ml) au sulphate de colistine, ce qui est cliniquement significatif, car la colistine est considérée comme un antibiotique de dernier recours.Les plasmides de type phage représentent une MGE polyvalente, car ils peuvent mobiliser les ARGs et les gènes HMRs via les 3 mécanismes de la HGT. Pris ensemble, les résultats de cette étude mettent en évidence la contribution des PLPs à la dissémination de la résistance aux antibiotiques dans les environnements agricoles et cliniques
Evaluation of rapid «Salmonella» immunoassays and characterization of bacterial isolates that cause false-negative and false-positive in the tests
No full textSalmonella spp. is a widely distributed Gram-negative foodborne pathogen that is a major cause of foodborne outbreaks in North America. The Public Health Agency of Canada (PHAC) estimates that approximately 88,000 Canadians are affected by foodborne Salmonellosis annually. In recent years, contaminated fresh produce has emerged as an important source of salmonellosis. Standardized culture methods for Salmonella spp. are considered as the "gold standard" in food diagnostics and are still in use today; however, they are laborious, time-consuming and must be confirmed by secondary biochemical tests. Immunoassays are the most commonly used rapid methods for the detection of Salmonella in food, and presumptive results are available within 8 to 24 hours. However, a common issue observed using immunoassays to test fresh produce for the presence of Salmonella, is a high percentage of false-positive test results due to the misidentification of closely related, non-Salmonella bacteria such as Citrobacter spp., Hafnia spp. and Proteus spp. In addition, there is also the chance of false-negative test results, due to high variation in surface antigens of Salmonella enterica. In this study, two commercially available immunoassays, the VIDAS UP Salmonella Phage Technology (SPT) Assay (BioMérieux, Saint-Laurent, Quebec, Canada, Inc.) and an antibody-based lateral-flow test, the Reveal 2.0 Salmonella Assay (Neogen Corporation, Lansing, Michigan, United States) were evaluated for their accuracy in detecting Salmonella. VIDAS UP Salmonella (SPT) assay correctly identified 52/54 (96.3%) of the Salmonella isolates that were tested. The Reveal 2.0 Salmonella Assay identified 43/54 (79.63%) of the Salmonella isolates correctly. However, both assays failed to identify one isolate each of Salmonella enterica serovars Hull and Duesseldorf. Several VIDAS UP Salmonella (SPT) enrichment samples were obtained from a fresh produce grower. These enrichments had previously tested presumptive positive for Salmonella, however, confirmatory tests did not indicate the presence of Salmonella. The enrichments were analyzed in order to obtain pure isolates of bacteria from the enrichment mixture that were responsible for the false positive test results. Three bacterial isolates that caused false-positive VIDAS UP Salmonella (SPT) reactions were isolated and subjected to whole genome sequencing and bioinformatic analysis. Blast analysis of the three false-positive isolates identified Citrobacter amalonaticus as the likeliest organism. The two isolates (one each) of S. Hull and S. Duesseldorf that produced false-negative results were analyzed in order to identify surface exposed components that are used as diagnostic targets in Salmonella immunoassays. Analysis of S. Duesseldorf showed that the flagella genes fljB and fliC differed significantly from other Salmonella isolates that tested positive, and the three C.amalonaticus isolates that caused false-positive test results. Analysis of the S. Hull genome identified a gene encoding a putative repression of phase I flagellin, which was located on a cryptic incomplete prophage. Both of these observations are likely responses for the lack of complete flagella on the surface of the S. Duesseldorf and S. Hull isolates, which may be responsible for the false-negative test results. The results of this work have identified the potential basis for false-positive and false-negative test results in rapid Salmonella immunoassays. The development of more selective immunoassays based on more specific monoclonal antibodies, identification of new antigens that are more specific to Salmonella and development of more selective enrichment media will lead to improved fresh produce testing and enhanced food safety in Canada.Salmonella spp. est un agent pathogène Gram négatif largement distribué qui est une cause majeure d'éclosion d'origine alimentaire en Amérique du Nord. L'Agence de la santé publique du Canada (ASPC) estime qu'environ 88,000 Canadiens sont touchés par la salmonellose d'origine alimentaire chaque année. Les méthodes de culture normalisées pour Salmonella spp. sont considérées comme « l'étalon d'or » à fin de diagnostic alimentaire et sont toujours utilisées aujourd'hui; cependant, ces méthodes sont laborieuses, longues et les résultats doivent être confirmés par des tests biochimiques secondaires. Les tests à base immunologique sont les méthodes les plus couramment utilisées pour la détection de Salmonella dans les aliments, et les résultats présomptifs sont disponibles à l'intérieur de 8 à 24 heures. Cependant, un problème communément observé en utilisant ces tests immunologiques pour tester les fruits et légumes pour la présence de Salmonella est un pourcentage élevé de résultats faussement positifs en raison de l'identification erronée de bactéries non-Salmonella étroitement apparentées, telles que Citrobacter spp., Hafnia spp. et Proteus spp. En outre, il existe également la possibilité de résultats faussement négatifs, en raison de la forte variation des antigènes de surface de Salmonella enterica. Lors de cette étude, deux tests immunologiques disponibles sur le marché, le test VIDAS Salmonella (SPT) utilisant la technologie de phage (BioMérieux, Montréal, Québec, Canada) et le test à immunochromatographie Reveal Salmonella 2.0 (Neogen Corporation, Lansing, Michigan, ÉU) ont été évalués pour leur précision dans la détection de Salmonella. Le test VIDAS (SPT) a correctement identifié 52/54 (96.3%) des isolats de Salmonella qui ont été testés. Le test Reveal 2.0 a identifié correctement 43/54 (79.63%) des isolats de Salmonella. Cependant, aucun des deux tests n'a permis d'identifier les isolats de Salmonella enterica serovars Hull ou Duesseldorf. Plusieurs échantillons d'enrichissement VIDAS (SPT) ont été obtenus auprès d'un producteur de produit frais. Ces enrichissements avaient précédemment donné des résultats présumés positifs pour Salmonella, mais les tests de confirmation n'indiquaient pas la présence de Salmonella. Les trois isolats bactériens qui ont provoqué des résultats faussement positifs lors de la détection à partir du VIDAS (SPT) ont été isolées et soumises à un séquençage génomique complet et à une analyse bioinformatique. L'analyse par Blast des trois isolats faussement positifs a identifié Citrobacter amalonaticus comme l'organisme le plus probable. Deux isolats ayant donné des résultats faussement positifs (S. Hull et S. Duesseldorf) ont été analysés afin d'identifier les composants exposés à la surface qui sont utilisés comme cibles de diagnostic dans les tests immunologiques de Salmonella. L'analyse de S. Duesseldorf a montré que les gènes de la flagelles, fljB et fliC, diffèrent significativement des autres isolats de Salmonella qui ont testé positifs ainsi que les trois isolats de Citrobacter amalonaticus ayant provoqué des résultats faussement positifs. L'analyse du génome de S. Hull a identifié un gène présumé d'encoder un répresseur de la flagelline de phase I, qui est situé sur un prophage cryptique. Ces deux observations suggèrent possiblement que l'absence de flagelles entiers à la surface des isolats de S. Duesseldorf et S. Hull peut être responsable des résultats des tests faussement négatifs. Les résultats de ce travail ont identifié la base potentielle pour les résultats faussement positifs et négatifs de Salmonella. Le développement des tests immunologiques plus sélectif basé sur des anticorps monoclonaux plus spécifiques, l'identification de nouvelles cibles plus spécifiques pour Salmonella ainsi que le développement de milieu d'enrichissement sélective, conduira à une amélioration des tests sur les fruits et légumes et à une meilleure sécurité alimentaire au Canada
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
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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