1,720,985 research outputs found
Evaluation of the mechanical properties of dental adhesives and glass-ionomer cements
No full textAdhesives and lining/base materials should relieve the stresses concentrated at the tooth/restoration interface. The study aimed at comparing the mechanical properties of eight adhesives and six glass-ionomer cements (GICs). The adhesives were applied on dentin disks, whereas 2 mm x 3 mm x 2 mm GICs specimens were prepared in a teflon mold. Vicker's hardness (VH), elastic modulus (E), creep (Cr) and elastic work (We/Wtot) were measured with a micro hardness indenter. One-way ANOVA and Tukey's test were used to compare the mechanical properties within each materials' type and among the materials' classes. Enamel and dentin were used as references. Significant differences were detected within each materials' type and among the materials' classes and enamel and dentin. GICs were superior to adhesives in VH and E and showed a VH similar to dentin. GICs presented mechanical properties more similar to enamel and dentin than adhesives
Influence of ozone application on the repair strength of silorane-based and ormocer-based composites
No full textPURPOSE:
To evaluate the effect of gasiform ozone on the repair strength of ormocer-based and silorane-based composites.
METHODS:
160 cavities were created in methacrylate cylinders. Half of the cavities were filled with a silorane-based composite, whereas the other half was filled with an ormocer-based composite. After storage (1 week, deionized water, 37 degrees C) the specimens of each restorative material were divided into two main experimental groups: in Group 1 the specimens were subjected to a 60-second ozone gas application; in Group 2 no pretreatment was performed (control). The corresponding adhesive of each restorative material was applied as the intermediate repair agent in both groups. Repair cylinders were then built up with the homologous material. Half of the specimens in each group were subjected to thermocycling (5,000 cycles, 5 degrees C-55 degrees C, dwell time 30 seconds, transfer time 5 seconds) prior to testing, whereas the other specimens were immediately tested. The repair strength was assessed with a shear test. The two-way ANOVA with pretreatment and thermocycling as the main factors was used to analyze the shear bond strength data within each restorative material.
RESULTS:
The pretreatment, the thermocycling and their interaction did not significantly affect the repair strength of either tested materials (P > 0.05). The ozone treatment did not significantly affect the repair strength. The silorane-based composite showed lower repair strengths compared to those of the ormocer-based composite. The immediate repair strengths in the ozone-treated and control groups were respectively, 28.1 (13.8) MPa and 28.8 (8.8) MPa for the silorane-based composite and 31.5 (9.3) MPa and 35.6 (10.6) MPa for the ormocer-based composite. After thermocycling, the repair strengths in the ozone-treated and control groups were 27.7 (9.7) MPa and 29.5 (11.1 ) MPa for the silorane-based composite and 31.4 (6.0) MPa and 34.2 (4.5) MPa for the ormocer-based composite. Mixed failures occurred most frequently in all experimental groups. In conclusion, ozone did not affect the repair strength of the tested silorane-based and ormocer-based composite
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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