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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
The effect of office bleaching on the color and bond strength of resin restorations
No full textBackground: Bleaching may affect the bond strength of existing composite fillings and may weaken it. Hence, the aim of this study was to find the best method of in-office bleaching with the least effect on microshear bond strength (MSBS) of existing composite resin fillings to tooth structure.
Materials and Methods: In this in vitro study, Class V cavities were prepared on buccal surface of 50 extracted third human sound molars. The cavities in 25 teeth had enamel axial walls, Group E, which were divided into five subgroups of E1 through E5 and in 25 teeth had dentin axial walls, Group D, which were divided into five subgroups of D1 through D5. Cavities were treated with Single Bond 2 adhesive system and restored with composite resin (Z250). The corresponding subgroups received similar bleaching methods and materials; 1 – not bleached, 2 – hydrogen peroxide (HP) 25%, 3 – HP + ultraviolet light, 4 – HP + light-emitting diode-curing device, and 5 – HP + diode laser. Teeth colors were monitored before and after bleaching, and MSBS test and failure modes were examined. Results were analyzed with one-way ANOVA and Kruskal–Wallis tests. P < 0.05 was considered significant.
Results: One-way ANOVA did not show differences in MSBS of enamel subgroups but showed significant differences in dentin subgroups (P < 0.00). Adhesive fracture in all of the subgroups was the most frequent mode of failure. Kruskal–Wallis test showed that laser was the most effective instrument to change ΔE.
Conclusion: Diode laser was the best method for tooth bleaching because lowering the shear bond strength between composite resin and enamel was minimum and also had the most ΔE in tooth bleaching
Effect of different surface treatments on microtensile bond strength of two resin cements to aged simulated composite core materials
No full textObjective: Roughening of the aged composite resin core (CRC) surface seems essential for durable adhesion. The aim of this study was to investigate the influence of various surface treatments and different resin cements on microtensile bond strength (µ TBS) between two aged core build-up composites (CBCs) and feldspathic ceramic.
Materials and Methods: A total of 16 composite blocks made of two CBCs, Core.it and Build-it were randomly assigned to four surface treatment groups after water storage and thermocycling (2 weeks and 500 cycles). Experimental groups included surface roughening with air abrasion (AA), hydrofluoric acid, pumice, and laser and then were bonded to computer-aided design/computer-aided manufacturing feldspathic ceramic blocks using two resin cements, Panavia F2 (PF), and Duo-link (DL). The µ TBS was tested, and the fracture mode was assessed. The data were analyzed with multiple analysis of variance to estimate the contribution of different surface treatments, resin cements, and two aged CRCs on µ TBS. Statistical significance level was set at α < 0.05.
Results: Surface treatment and cement type significantly affected bond strength (P < 0.001) but the type of CRC did not (P = 0.468). Between roughening methods, the highest and the lowest values of µ TBS were sequentially obtained in AA and Er.YAG laser groups. The highest bond strength was in AA group cemented with PF (31.83 MPa). The most common failure mode was cohesive fracture in the cement.
Conclusion: Different surface treatments had different effects on µ TBS of aged CRCs to feldspathic ceramics. PF was significantly better than DL
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
Effect of hydrofluoric acid surface treatments on micro-shear bond strength of CAD/CAM ceramics
No full textDispelling 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
Effect of fluoride-free and fluoridated carbamide peroxide gels on the hardness and surface roughness of aesthetic restorative materials
No full textBackground: Bleaching products may show some side effects on soft and hard tissues and restorative materials in the oral cavity. This study evaluated the effect of carbamide peroxide gel with and without fluoride ions on the microhardness and surface roughness of tooth-colored restorative materials.
Materials and Methods: In this in-vitro study, 76 cubic specimens (4 mm 3 × 4 mm 3 × 3 mm 3 ) were fabricated from 4 aesthetic A3-shade restorative materials. These materials consisted of two composite resins and two glass ionomers. The specimens made from each material were treated with the following surface treatments: 1. Control group: The specimens were not bleached and were stored in normal saline. Group 2. Fluoridated 20% carbamide peroxide gel, treated 3 h a day for 4 weeks. Group 3. Treated 1 h a day with fluoride-less 22% carbamide peroxide for two weeks. From each group, three other specimens were selected to be evaluated in terms of changes in surface roughness, under scanning electron microscopy (SEM).
Results: In this study, fluoridated 20% carbamide peroxide gel increased the microhardness of the four aesthetic restorative materials. The fluoride-free carbamide peroxide 22% reduced the microhardness of the four used materials, which this change was significant for Vitremer and Amelogen. SEM analyses showed changes in surface roughness of glass ionomer specimens.
Conclusion: The effect of bleaching on the microhardness of restorative materials is material dependent. Before the application of bleaching systems on the glass ionomer materials, the application of a protective barrier should be considered
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