1,720,964 research outputs found
Phenotypes and genotypes of erythromycin-resistant Streptococcus pyogenes strains in Italy and heterogeneity of inducibly resistant strains.
No full text
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
Molecular characterization of clinical Streptococcus pneumoniae isolates with reduced susceptibility to fluoroquinolones emerging in Italy
No full textFifteen Streptococcus pneumoniae clinical isolates with reduced fluoroquinolone susceptibility (defined as a ciprofloxacin MIC of ≥4 μg/ml), all collected in Italy in 2000–2003, were typed and subjected to extensive molecular characterization to define the contribution of drug target alterations and efflux mechanisms to their resistance. Serotyping and pulsed-field gel electrophoresis analysis indicated substantial genetic unrelatedness among the 15 isolates, suggesting that the new resistance traits arise in multiple indigenous strains rather than through clonal dissemination. Sequencing of the quinolone resistance-determining regions of gyrA, gyrB, parC, and parE demonstrated that point mutations producing single amino acid changes were more frequent in topoisomerase IV (parC mutations in 14 isolates and parE mutations in 13) than in DNA gyrase subunits (gyrA mutations in 7 isolates and no gyrB mutations observed). No isolate displayed a quinolone efflux system susceptible to carbonyl cyanide m-chlorophenylhydrazone; conversely, four-fold or greater MIC reductions in the presence of reserpine were observed in all 15 isolates with ethidium bromide, in 13 with ulifloxacin, in 9 with ciprofloxacin, in 5 with norfloxacin, and in none with five other fluoroquinolones. The effect of efflux pump activity on the level and profile of fluoroquinolone resistance in our strains was minor compared with that of target site modifications. DNA mutations and/or efflux systems other than those established so far might contribute to the fluoroquinolone resistance expressed by our strains. Susceptibility profiles to nonquinolone class antibiotics and resistance-associated phenotypic and genotypic characteristics were also determined and correlated with fluoroquinolone resistance. A unique penicillin-binding protein profile was observed in all five penicillin-resistant isolates, whereas the same PBP profile as S. pneumoniae R6 was exhibited by all six penicillin-susceptible isolates. This is the first attempt to molecularly characterize clinical isolates of S. pneumoniae with reduced susceptibility to fluoroquinolones emerging in Italy
New Tn916-related elements causing erm(B)-mediated erythromycin resistance in tetracycline-susceptible pneumococci
No full textObjectives: To analyse the as yet unexplored genetic elements encoding erm(B)-mediated erythromycin
resistance in tetracycline-susceptible pneumococci.
Methods: Sixteen Streptococcus pneumoniae clinical isolates sharing erm(B)-mediated erythromycin
resistance and susceptibility to tetracycline were used. Gene detection was performed by PCR using
both established and specially designed primers. S. pneumoniae R6, Streptococcus pyogenes 12RF
and Enterococcus faecalis JH2–2 were used as recipients in mating experiments.
Results: Of the 16 test strains, 14 bore an unexpressed tet(M) gene which in 13 strains had a genetic
linkage with erm(B). Three isolates yielded a 3.2 kb and 10 an 11.9 kb erm(B)/tet(M) amplicon. The
former three showed genetic organizations similar to that of the composite element Tn3872, where the
erm(B)-carrying Tn917 transposon is inserted into a Tn916-like element. Of the latter 10 isolates, 9
showed genetic organizations substantially overlapping with that of Tn6002, a newly sequenced
erm(B)-containing Tn916-related transposon. The tenth isolate carried a novel composite element
(designated Tn6003) resulting from the insertion into a Tn6002-like transposon of a fragment [designated
macrolide–aminoglycoside–streptothricin (MAS) element] containing a second erm(B) (lacking
the stop codon) and a variant of the aadE–sat4–aphA-3 cluster. The two tet(M)-negative isolates had
different Tn3872-related elements, one containing a complete and one a deleted MAS fragment.
Conjugative transfer was obtained from donors carrying Tn6002-related elements, not from donors
carrying Tn3872-related elements.
Conclusions: In tetracycline-susceptible pneumococci with erm(B)-mediated erythromycin resistance,
the erm(B) gene is carried on a variety of Tn916-related genetic elements either lacking tet(M) or, more
often, carrying an unexpressed tet(M) gene
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
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
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