1,720,960 research outputs found
Alicyclobacillus pohliae sp. nov., a novel thermophilic endospore-forming bacterium isolated from geothermal soil of the north-west slope of Mount Melbourne (Antarctica)
No full textGram-positive, rod-shaped, endospore-forming, thermophilic bacteria were isolated from a geothermal soil collected on the north-west slope of Mount Melbourne in Antarctica. They grew aerobically at 42–60°C (optimum 55°C) and at pH 4.5–7.5 (optimum pH 5.5). Phylogenetic analysis of 16S rRNA gene sequences showed that these isolates were related most closely to the type strain of Alicyclobacillus pomorum (91% similarity). Growth occurred in the presence of ferrous iron at micromolar concentrations and acid was produced from various sugars. Iso-branched fatty acids C15 : 0 (45.56 %) and C17 : 0 (35.81 %) were the most abundant cellular fatty acids. The DNA G+C content was 55.1 mol%. On the basis of phenotypic and phylogenetic characteristics, it is concluded that these strains represent a novel species of the genus Alicyclobacillus, for which the name Alicyclobacillus pohliae sp. nov. is proposed. The type strain is MP4T (=CIP 109385T =NCIMB 14276T)
Detection of IncP replicon-specific regions in DNA from Antarctic microbiota
No full textPlasmids capable of horizontal transfer contribute to the adaptability of bacteria, as they may provide genes that enable their hosts to cope with different selective pressures. Only limited information is available on plasmids from Antarctic habitats, and up until now surveys have only used traditional methods of endogenous plasmid isolation. The method based on primer systems, designed on the basis of published sequences for plasmids from different incompatibility (Inc) groups, is appropriate to detect the replicon-specific regions of corresponding plasmids in cultured bacteria, or in total community DNA, which share sufficient DNA similarity with reference plasmids at the amplified regions. In this study, we applied broad-host-range plasmid-specific primers to DNA from microbial samples collected at six different locations in Northern Victoria Land (Antarctica). DNA preparations were used as targets for PCR (polymerase chain reaction) amplification with primers for the IncP (trfA2) and IncQ (oriV) groups. PCR products were Southern blotted and hybridized with PCR-derived probes for trfA2 and oriV regions. This approach detected the occurrence of IncP-specific sequences in eight out of fifteen DNA samples, suggesting a gene-mobilizing capacity within the original habitats
Detection of replicon-specific regions in DNAs derived lrom antarctic microbial community
No full textDetection of replicon-specific regions in DNAs derived from antarctic microbial community
No full textUse of a promoter-probe vector system in the cloning of regulatory sequences from a Pseudomonas corrugata strain resistant to hexavalent chromium
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
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