1,721,020 research outputs found
Dynamics of pneumococcal colonization in healthy Dutch children
Get PDFA recent study of pneumococcal colonization in 3198 healthy children of 1-19 years of age in The Netherlands showed pneumococcal colonization in 19 % of the children, with a peak incidence of 55 % at the age of 2 years; an age-related serotype distribution was also found. In the present study, the genetic background and resistance profiles of 578 pneumococcal isolates from the latter study were characterized by means of chromosomal genotyping and susceptibility testing. In contrast to the age-related serotype distribution observed previously, the genetic background of the strains was not age related. Few strains were found showing close homology (>95 %) with the international clones Spain(9V)-3 (ten isolates showed homology), England(14)-9 (four isolates), Tennessee(23F)-4 (two isolates), CSR(14)-10 (one isolate) and Sweden(15A)-25 (one isolate). In total, 19 % of strains showed resistance to one or more antibiotics. Resistance to cotrimoxazole, tetracycline, erythromycin and penicillin was found in 12.9, 5.6, 5.0 and 2.7 % of isolates, respectively. Multidrug resistance was found in 1.9 % of strains. In conclusion, pneumococcal colonization isolates from healthy Dutch children represent a heterogeneous, mostly antibiotic susceptible, genetic population.<br/
Tolerance of staphylococcus aureus to ß-lactam antibiotics
Get PDFPenicillin has a bactericidal action on actively dividing bacteria. If
protein synthesis of bacteria exposed to penicillin is inhibited, for
example by the addition of chloramphenicol or the omission of an
essential amino acid from the medium, the bactericidal action of penicillin
changes into bacteriostasis (6). Rogers (10) and Shockman (11) found with S. aureus and Streptococcus faecalis respectively that
inhibition of protein synthesis by chloramphenicol was accompanied by
a sharp decline in the autolytic activity of the cells. These results
supported their hypothesis that bacteria are lysed under the influence
of penicillin because the equilibrium between peptidoglycan synthesis
and autolysis shifts in the direction of the latter process as a
result of the action of the ß-lactam antibiotic. The correctness of
the hypothesis of Rogers and Shockman was supported by the work of
Tomasz et al. (13), who isolated an autolysin-deficient mutant of
Streptococcus pneumoniae which was not killed after exposure to
penicillin. Tomasz et al. (13) called the absence of the bactericidal
action of penicillin, tolerance for this agent. Since then, tolerant
strains belonging to various species of bacteria have been isolated
from clinical material. In previous studies (3,4) we showed that
S. aureus strains can be divided into tolerant and nontolerant strains
on the basis of their survival in vitro in the presence of high
concentrations of methicillin ( >:- 64 .ug/ml). According to the observations
of Rogers (10), the mechanism of the reduced lysis in tolerant
S. aureus strains exposed to high concentrations of methicillin could
be based on inhibition of protein synthesis. The existence of such a
link has already been demonstrated by Mychajlonka et al. (8) for
tolerant Streptococcus mutans strains. In the present study we
investigated peptidoglycan, RNA and protein synthesis in two tolerant
and two nontolerant S. aureus strains after exposure to a low and a
high concentration of methicillin
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
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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