1,720,958 research outputs found
Shaping outcomes using two Ni-Ti rotary instruments in simulated canals.
No full textAIM: The aim of this study was to compare the shaping ability of Mtwo and ProTaper instruments in simulated curved root canals in resin blocks. METHODS: The study was carried out using 40 simulated canals in resin blocks, all of which had the same canal diameter (0.70 mm>D>0.20 mm), length (16 mm), and angle of curvature (40 degrees). These 40 canals were divided into 2 groups of 20 specimens. Both before and after instrumentation, all the resin specimens were photographed, and all the canals examined were measured at 4 different points of reference. Using a computer image analysis program, the photographs of corresponding sections were superimposed on one another. In this way we sought to evaluate the shaping ability of these 2 systems in relation to specific portions of the root canal, also with regard to maintenance of original canal curvature. The results were analysed using Student's t-test. RESULTS: Both rotary systems were found to respect the original root canal curvature, particularly in the areas most at risk of modification, namely the outer aspect of the curve in the apical third of the canal. The Mtwo instruments caused less transportation of the apex than the ProTaper instruments, but this difference was not statistically significant (P>0.05). CONCLUSION: According to the results of this study, both these instruments respected the original canal curvature, particularly in the areas at most risk of modification, and they also showed good shaping ability in curved canals, with minimum transportation of the apex
Bond strength to deep coronal dentin: effect of bonding strategies.
No full textThe aim of this study was to evaluate bond strength at the composite-adhesive-deep dentin interface following pre-treatment with sodium hypochlorite using 4 different types of enamel-dentin adhesive and a composite for the core. From 60 healthy human molars, cylindrical samples (3 mm high) were obtained using a special slow-speed saw. Cavities with 2-5-mm diameters were made in all the samples. Samples were assigned to 8 groups, 4 groups were designated as experimental groups and were irrigated with NaOCl and the other 4 groups designated as control groups were irrigated with distilled water. Adhesive systems were applied to the samples and then restored using a core build-up composite. Samples were subjected to shear stress test using an electronic dynamometer. The data were analyzed using one-way ANOVA and the Tukey test (P<0.05). The results, in terms of bond strength, demonstrate that the two-step self-etch adhesive systems generate a stronger bond than the other systems considered in the study (P<0.05). The results also show that pre-treatment with hypochlorite does not seem to influence the bond strength of self-etch adhesive systems. This in vitro study demonstrates that there exist differences in bond strength between self-etch and etch & rinse adhesive systems on deep dentin pretreated with sodium hypochlorite to simulate endodontic treatment
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
Trattamento delle infezioni urinarie complicate con un nuovo farmaco di particolare efficacia: la Norfloxacina.
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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
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