130,376 research outputs found
Supragingival plaque microbial analysis in reflection to caries experience. [Elektronisk resurs]
No full textABSTRACT: BACKGROUND: Dental caries develops as a result of the metabolism of carbohydrates by cariogenic bacteria present in a complex biofilm. The present study aimed to examine if bacteria in pooled supragingival plaque samples quantified using a "checkerboard DNA-DNA hybridization" based panel of caries-related bacteria, could reflect the caries experience in a manner similar to saliva samples analysed using a chair-side method in a previous investigation. METHODS: A total of 86 mothers and their children aged 4-6 years and 12-16 years old participated. Caries experience (DMFT/dmft; Decayed, Missing and Filled Teeth for permanent and primary teeth) was registered clinically and radiographically. Caries was recorded at the D3 level (caries into dentine). The D/d component was divided into three categories. A pooled supragingival plaque sample per participant was obtained from posterior approximal sites. Analyses of 15 bacterial species were performed using the checkerboard DNA-DNA hybridisation technique. RESULTS: No significant relationships were found between the bacterial scores and DMFT/dmft nor D/d groups. CONCLUSIONS: Unlike the saliva samples and the chair-side method, interproximal pooled plaque samples analysed using the "checkerboard DNA-DNA hybridization technique" did not reveal any significant relations between the bacterial counts and the caries experience
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
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
Intra-familial Cariological Studies on a Saudi Population
No full textObjectives: The aims of this thesis were to: 1) describe the caries experience and caries-related factors in mothers and their preschool and school children, 2) correlate quantified supragingival plaque bacteria between mothers and their children and identify possible microbial associations, 3) examine whether bacteria in pooled supragingival plaque samples, quantified using a “checkerboard DNA-DNA hybridisation”-based panel of caries-related bacteria, could reflect the caries experience in a manner similar to saliva samples analysed using chair-side methods, 4) measure the effects of six weeks’ use of a 5,000 ppm fluoride toothpaste on caries-related factors in dental plaque and saliva and 5) consecutively assess the caries risk following six weeks’ use of 5,000 ppm fluoride toothpaste using the “Cariogram”. Materials and methods: A total of 258 individuals (86 mothers and two of their children, 4-6 and 12-16 years old) were examined cross-sectionally (Studies I, II & III) out of which 17 families were enrolled (mothers and 13- to 17-year-old children) a year later in a longitudinal six weeks trial (Studies IV & V) in which 5,000 ppm fluoride toothpaste was administered. In Study I, anamnestic data were collected, and clinical oral examinations and chair-side tests were performed. In Studies II and III, pooled interproximal supragingival plaque samples were analysed for their content of bacterial strains using the checkerboard DNA-DNA hybridisation technique. In Study II, microbial associations for all three age groups together were sought using cluster analysis, while principal components analysis (PCA) was used for each of the three age groups separately. In Study III, relationships between the bacterial scores and the caries experience (DMFT/dmft and D/d groups) were assessed. In Study IV, the participants were assessed on four (two weeks apart) visits. Sampling of approximal fluid for fluoride analysis and approximal plaque for organic acid analysis was performed. Chair-side tests were performed to register the lactic acid production rate on the tongue, approximal plaque pH, salivary buffer capacity and counts of cariogenic microorganisms. In Study V, caries-risk assessment following the use of 5,000 ppm fluoride toothpaste was performed consecutively on each of the four visits using the “Cariogram” software. Results: In Study I, the mean caries experience (DMFT/dmft) was high in the mothers and their younger and older children (12.4 ± 5.3, 9.0 ± 5.0 and 5.8 ± 4.1, respectively). The DMFT/dmft increased with higher salivary mutans streptococci counts in all age groups (p<0.05). The caries experiences of the children were positively correlated with those of their mothers (R24-6=0.12, R212-16=0.18, p<0.01). A positive association between mothers and both children was evident for toothbrushing habits, snacking frequency and gingival health (p<0.05). An association between plaque scores, salivary buffer capacity and mutans streptococci (MS) counts was found between mothers and older children (p<0.05). In Study II, three complexes were formed from the dendrogram. PCA results were similar in all three groups. The correlation analyses of bacterial counts between mothers and their children showed a significant association for most of the bacterial strains (p<0.05 or 0.01). In Study III, no significant relationships were found between the bacterial scores and DMFT/dmft or D/d groups. In Study IV, the six weeks’ use of 5,000 ppm fluoride toothpaste significantly increased the approximal fluid fluoride concentration, and salivary buffer capacity. It also decreased the lactic acid production rate, plaque acideogenicity (AUC5.7, AUC6.2, maximum pH fall) and salivary mutans streptococci counts. In Study V, the use of 5,000 ppm fluoride toothpaste resulted in a statistically significant modification of the caries-risk profile, increasing the actual chance of avoiding caries in the future among the mothers and teenagers at each visit following baseline (p<0.01). The changes essentially related to the salivary parameters [buffer capacity, MS, and lactobacilli (LB) counts]. A statistically significant linear trend was observed for MS counts (p<0.01) and the number of individuals with a salivary concentration of MS < 103 increased on each visit. The same trend was also observed for LB and buffer capacity scores (p=0.04 and p=0.03 respectively). Conclusions: The caries experience in Saudi mothers and their children is high, with similar contributory caries-related factors. Supragingival plaque microbiota are correlated between the mothers and their children with similar supragingival plaque microbial associations present in all three family members. The analysed pooled plaque samples did not reveal any significant relationships between the bacterial counts and the caries experience in any of the family members. The 5,000 ppm fluoride toothpaste has the ability to reduce the cariogenic potential of dental plaque and saliva, as well as the caries-risk profile
"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.
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
The R&D Tax Incentives
No full textThis article sets out some background information and reflections of the author on the R&D tax incentive schemes included in the Common Corporate Tax Base (CCTB) Proposal. In particular the author analyzes the stimulus to private R&D through ad hoc tax incentives included in the CCTB Proposal and dives into the actual provisions included in the Proposal highlighting the most relevant issues connected with their design and interpretation. Moreover, the author explores the interaction between the CCTB Proposal and the granting by Member States of domestic R&D tax incentives
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