1,721,205 research outputs found
The evolution diversity and ecology of the dark matter of the biosphere: Bacteriophages
No full textColloque organisé par André M. Comeau, Henry M. Krisch and Nicholas H. Mann du 26 au 31 mars 2007 L’objectif principal de cette rencontre était d’obtenir une meilleure appréciation du rôle des phages dans la Biosphère. A cette fin ont été réunis vingt «world leaders» travaillant sur différents aspects du problème. Participants Stephen Abedon, Mya Breitbart, Harald Brüssow, Sherwood Casjens, Martha Clokie, André Comeau, Mike Dyall-Smith, Jonathan Filée, Patrick Forterre, Graham F. Hatfull, Chr..
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
Mycobacteriophages: Diversity, Dynamics, and Therapy
No full textBacteriophages—viruses that infect bacteria—are the most numerous biological entities in the biosphere. The phage population is not only vast but dynamic and old, and perhaps not surprisingly, highly diverse genetically. We are exploring and defining this biological diversity by isolating and genomically characterizing individual phages, and through comparative genomic analyses. The development of large integrated research-education programs, such as the Science Education Alliance Phage Hunters Advancing Genomics and Evolutionary Science (SEA-PHAGES) program, have established a large collection of 15,500 individual phages—all isolated on bacterial hosts within the phylum Actinobacteria—of which over 3000 are fully sequenced. These genomes are highly diverse genetically, even if isolated on the same bacterial strain, and are richly populated in genes of unknown function. We propose that many of these genes are involved in the dynamic relationships between bacteria and their viruses, either promoting or countering viral defense systems, or denying competing phages the opportunity to superinfect infected cells. Examples of these include prophage-mediated defense systems in which integrated prophages of temperate viruses lysogenically express genes that prevent attack by unrelated (heterotypic) phages. These systems are prevalent among temperate phages and can act with exquisite specificity in their defense profiles. Phages can also encode their own counter-defense systems to negate the functions of these prophage-mediated defenses. These contributions to microbial dynamics dictate the phage susceptibility profiles of individual strains of pathogenic bacteria, adding complexity to the prospects for the broad therapeutic use of phages against bacterial infections. However, we have shown that the administration of a three-phage cocktail engineered and personalized to a specific highly antibiotic-resistant strain of Mycobacterium abscessus contributes to substantial clinical improvement
Genome organization of Mycobacteriophage Tweety.
No full textPhage Tweety is a member of Subcluster F1, is temperate, has a siphoviral morphology (inset, electron micropraph; scale marker, 100 nm), and its genome organization illustrates several common features. The genome is represented as a bar with markers every 1 kbp, and the predicted genes are shown as colored boxes above or below the genome, indicating rightwards- and leftwards-transcription, respectively. Gene numbers are shown within the boxes and predicted functions are shown above. The virion structure and assembly genes are arranged in a rightwards-transcribed operon at the left end of the genome (genes 1 to 25), followed by the lysis cassette. The repressor (45) and putative Cro-like (46) genes are divergently transcribed, and the integration cassette (attP and 43) are located nearby, with attP defining a “left arm” from cos–attP and a “right arm” from attP–cos. Note that the left arm genes—predominantly the virion structure and lysis genes—are relatively large and have known functions, whereas the right arm genes are relatively small, and most have unknown functions. Shown are the positions of the MPME mobile element and the counterdefense gene, 54. The positions of putative early and later lytic promoters as determined by RNAseq are indicated. Note that genes are arranged in long operons such that there are relatively few transcriptional changes (tdc), such as at the 25/26 and 45/46 junctions.</p
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