1,720,957 research outputs found
Pyrosequencing: sequence typing at the speed of light
No full textNucleotide sequencing is an established method for gaining information relating to partial gene, whole gene, or whole genome sequence. Here we describe some of the background leading to the advent of modern nucleotide sequencing and how it has led to the development of Pyrosequencing, a relatively new method for real-time nucleotide sequencing. In particular, we describe how this method can be used for typing bacterial pathogens.</p
Genotypic characterization of Neisseria meningitidis using Pyrosequencing
No full textPyrosequencing involves the synthesis of single-stranded deoxyribonucleic acid leading to rapid and accurate analysis of nucleotide sequences. This article describes the development of typing assays for the characterization of Neisseria meningitidis using Pyrosequencing. This involved developing methods for the nucleotide sequence analysis of important variable regions contained on a major capsule gene and on outer membrane protein genes that are used for grouping, typing, and subtyping meningococci. To achieve this, primers were designed for amplification of three genes, siaD, porB, and porA from the four main serogroups B, C, Y, and W135. To facilitate throughput and reproducibility, the method was also automated. Data from 717 isolates have shown that Pyrosequencing can be used for the single nucleotide polymorphism and sequence-analysis characterization of meningococci.</p
A novel method for preparing single-stranded DNA for pyrosequencing
No full textPyrosequencing technology is a powerful genotyping tool that requires the generation of single stranded DNA. Currently, two simple, solid-phase-based methods are available for this, but they require special equipment, they are not automated, and they are relatively expensive because of the need for biotinylated polymerase chain reaction primers. In this article, an enzymatic liquid-phase method for the generation of high-quality, single-stranded DNA, and its novel use for Pyrosequencing are described. The method has also been fully automated.</p
Multilocus sequence typing: Data analysis in clinical microbiology and public health
No full textNumerous computer-based statistical packages have been developed in recent years and it has become easier to analyze nucleotide sequence data and gather subsequent information that would not normally be available. Multilocus sequence typing (MLST) is used for characterizing isolates of bacterial and fungal species and uses nucleotide sequences of internal fragments of housekeeping genes. This method is finding a place in clinical microbiology and public health by providing data for epidemiological surveillance and development of vaccine policy. It adds greatly to our knowledge of the genetic variation that can occur within a species and has therefore been used for studies of population biology. Analysis requires the detailed interpretation of nucleotide sequence data obtained from housekeeping and nonhousekeeping genes. This is due to the amount of data generated from nucleotide sequencing and the information generated from an array of analytical tools improves our understanding of bacterial pathogens. This can benefit public health interventions and the development of enhanced therapies and vaccines. This review concentrates on the analytical tools used in MLST and their use in the clinical microbiology and public health fields.</p
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
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