130,733 research outputs found
Investigation into the mobile genetic elements of Clostridium difficile
No full textClostridium difficile is a pathogenic bacterium that can colonise both humans and various animals. Toxin production leads to clinical symptoms ranging from mild to severe diarrhoea and can result in potentially fatal pseudomembranous colitis. These symptoms are caused by the disruption of the cytoskeleton and tight junctions of gut epithelial cells by the toxins. Genomic sequencing of C. difficile has indicated the chromosome carries a number of mobile genetic elements including conjugative transposons, which can encode antibiotic resistance genes. Analysing the sequence of a number of C. difficile strains indicated that each genome carries at least one and often multiple conjugative transposons. For many of the genes on these elements, functions were predicted using various bioinformatic tools. The study of conjugative transposons in C. difficile has been limited by the lack of resistance genes encoded by the elements. Therefore, an antibiotic resistance gene was inserted into six of the elements in strains 630 and R20291 and filter-matings performed. Conjugative transfer was shown for all elements from strain 630 but not for Tn6103 from R20291. The study of transconjugants of these matings showed the pathogenicity locus, encoding the two major toxins of C. difficile, to transfer at a low frequency into a non-toxigenic recipient strain. Whole genome sequencing of transconjugants determined that the transfer is not limited to the pathogenicity locus but includes varying sizes of chromosomal DNA flanking the pathogenicity locus. RNA-seq was used for the comparison of mutants for transcriptional regulators of conjugative transposons CTn2 and CTn4, however no significant differential expression was detected. Furthermore, strain 630Δerm, a commonly used laboratory strain for the generation of knockout mutants, was compared to the wildtype strain 630. A predicted oxidative stress operon was upregulated in 630Δerm which raises the question of the biological impact of these results on the knockout model
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
"Can I Be at Risk of Getting AIDS?" A Linguistic Analysis of Two Internet Columns on Sexual Health
No full textRecent global statistics highlight that, out of all new cases of HIV infection, 45% are diagnosed in young people (UNAIDS 2008). Despite a range of new initiatives aimed at increasing young people's knowledge of HIV at the beginning of the first decade of the twenty-first century (UNAIDS 2001), latest figures highlight that such initiatives have not been wholly successful in preventing new infection in young people (UNAIDS 2011). In light of this, the language patterns that young people use when seeking information about HIV/AIDS are investigated. Our focus in particular is on computer-mediated-communication, a relatively under-researched area in the sphere of health communication. Building on previous research (Locher 2006, 2010; Harvey et al. 2008; Harvey 2013), we examine one UK and one US Internet-based, professional, health advice column as sources of advice-information for young people. Despite numerous established health campaigns, young advice-seekers' questions reflect misinformed conceptions, such as the conflation of HIV and AIDS and confusion as to the way in which the virus can be contracted. Our linguistic research gives access to young people's lay beliefs about sexual health and highlights the need to redress such beliefs, with the aim of improving the effectiveness of health education initiatives. We suggest that computer-mediated communication can be one effective medium through which to assess young people's knowledge about HIV/AIDS, as well as effectively disseminating sexual health advice and information by health care bodies
The effect of induced alkalosis and submaximal cycling on neuromuscular response during sustained isometric contraction
No full textThe aim of this study was to determine if inducing metabolic alkalosis would alter neuromuscular control after 50 min of standardized submaximal cycling. Eight trained male cyclists (mean age 32 years, s¼7; _V O2max 62 ml kg71 min71, s¼8) ingested capsules containing either CaCO3 (placebo) or NaHCO3 (0.3 g kg71 body mass) in eight doses over 2 h on two separate occasions, commencing 3 h before exercise. Participants performed three maximal isometric voluntary contractions (MVC) of the knee extensors while determining the central activation ratio by superimposing electrical stimulation both preingestion and post-exercise, followed by a 50-s sustained maximal contraction in which force, EMG amplitude, and muscle fibre conduction velocity were assessed. Plasma pH, blood base excess, and plasma HCO3 were higher (P50.01) during the NaHCO3 trial. After cycling, muscle fibre conduction velocity was higher (P50.05) during the 50-s sustained maximal contraction with NaHCO3 than with placebo (5.1 m s71, s¼0.4 vs. 4.2 m s71, s¼0.4) while the EMG amplitude remained the same. Force decline rate was less (P50.05) during alkalosis-sustained maximal contraction and no differences were shown in central activation ratio. These data indicate that induced metabolic alkalosis can increase muscle fibre conduction velocity following prolonged submaximal cycling
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Mobile genetic elements in Clostridium difficile and their role in genome function.
No full textApproximately 11% the Clostridium difficile genome is made up of mobile genetic elements which have a profound effect on the biology of the organism. This includes transfer of antibiotic resistance and other factors that allow the organism to survive challenging environments, modulation of toxin gene expression, transfer of the toxin genes themselves and the conversion of non-toxigenic strains to toxin producers. Mobile genetic elements have also been adapted by investigators to probe the biology of the organism and the various ways in which these have been used are reviewed
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
Scholarly Communication and Publishing Lunch and Learn Talk #11: The ULS Open Access Author Fee Fund
No full textAt the May 2014 talk, you will learn about the ULS Open Access Author Fee Fund--what it is, why we do it, how it works, and how the program is going so far
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