1,720,973 research outputs found
Ecological dynamics of plasmid transfer and persistence in microbial communities
No full textPlasmids are a major driver of horizontal gene transfer in prokaryotes, allowing the sharing of ecologically important accessory traits between distantly related bacterial taxa. Within microbial communities, interspecies transfer of conjugative plasmids can rapidly drive the generation genomic innovation and diversification. Recent studies are starting to shed light on how the microbial community context, that is, the bacterial diversity together with interspecies interactions that occur within a community, can alter the dynamics of conjugative plasmid transfer and persistence. Here, I summarise the latest research exploring how community ecology can both facilitate and impose barriers to the spread of conjugative plasmids within complex microbial communities. Ultimately, the fate of plasmids within communities is unlikely to be determined by any one individual host, rather it will depend on the interacting factors imposed by the community in which it is embedded
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
The Sociality and Evolution of Plasmid-Mediated Antimicrobial Resistance
Get PDFOveruse and misuse of antibiotics has led to the global spread of antimicrobial resistance, threatening our ability to treat bacterial infections. The horizontal acquisition of multidrug resistance (MDR) plasmids, from other bacterial lineages, has been instrumental in spreading resistance. Newly acquired plasmids are often poorly adapted to hosts causing intragenomic conflicts, reducing the competitiveness of plasmid-carrying strains. Costs can be overcome by positive selection for plasmid-encoded adaptive traits in the short-term, or ameliorated by compensatory evolution in the long-term. How the selection and adaptation of MDR plasmids varies with antibiotic treatment remains unclear. First, I demonstrate that the selective conditions for the maintenance of an MDR plasmid are dependent upon the sociality of resistance it encodes. Selection for efflux of antibiotics, a selfish trait, occurred at very low concentrations of antibiotic, far below the minimum inhibitory concentration of sensitive plasmid-free strain. In contrast, selection for inactivation of antibiotics, a cooperative trait, increased the amount of antibiotic required to select for the MDR plasmid, allowing sensitive plasmid-free bacteria to survive high levels of antibiotic. These selection dynamics were only accurately predicted when mathematical models included the mechanistic details of antibiotic resistance. Secondly, I show that the trajectory of evolution following MDR plasmid acquisition varies with antibiotic treatment. Tetracycline treatment favoured a distinct coevolutionary trajectory of chromosomal resistance mutations coupled with plasmid mutations impairing plasmid-borne resistance. This led to high-level, low-cost antibiotic resistance, but also produced an integrated genome of co-dependent replicons that may limit the onward spread of co-adapted MGEs to other lineages. This evolutionary trajectory was strikingly repeatable across independently evolving populations despite the emergence of multiple competing lineages within populations. The results presented here demonstrate that the interaction between positive selection and compensatory evolution can help to explain the persistence of MDR plasmids in the clinic and the environment
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
- …
