1,721,185 research outputs found
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
Limited decalcification/diffusion of self-adhesive cements into dentin
No full textResin cement diffusion into dentin may differ as a function of the pre-treatment regimen. Since self-adhesive cements do not require substrate pre-treatment for luting, penetration of and interaction with the underlying dentin are questioned. We hypothesized that differences in the resin cement diffusion into dentin may exist among current commercial adhesive cements. Composite cylinders were luted on mid-coronal dentinal surfaces by an etch-and-rinse cement (Calibra), a self-etching system (Panavia F 2.0), and 4 self-adhesive cements (Multilink Sprint, Rely X Unicem, G-Cem, Bis-Cem). Dentin/ cement interfacial characteristics were analyzed by a staining technique (Masson's trichrome) and by scanning electron microscopy. Conventional acid etching resulted in partially infiltrated adhesive interfaces differing from those achieved with the application of self-etching primer. No hybrid layer and/or resin tag formation was detectable at the interfaces bonded with self-adhesive cements. Limited decalcification/infiltration was observed for self-adhesive cements into the underlying dentin. Self-adhesive cements were not able to demincralize/dissolve the smear layer completely
Dentin treatment effects on the bonding performance of self-adhesive resin cements
No full textThe effects of dentin surface treatments on the microtensile bond strengths and on the interfacial characteristics of self-adhesive resin cements were investigated. Flat dentin surfaces were obtained from human molars and were treated as follows: (i) no treatment of dentin; (ii) 0.1 M EDTA scrubbed for 60 s; or (iii) 10% polyacrylic acid applied for 30 s. Three self-adhesive cements were used to lute composite overlays on deep-coronal dentin surfaces in the presence of simulated pulpal pressure (15 cm of H(2)O). Bonded specimens were cut into beams 1 mm thick and stressed in tension until failure. Fractured sticks were examined under a scanning electron microscope. Additional specimens were stained with Masson's trichrome and observed under light microscopy for interfacial evaluations. The bond strength to dentin of the hydrophobic and solvent-free cement (RelyX Unicem) was unaffected by the tested dentin treatments. The bond strength of the 2-hydroxyethyl methacrylate (HEMA)-based cement (Bis-Cem) decreased after treatment of dentin with EDTA and/or polyacrylic acid. The hydrophilic and water-containing cement (G-Cem) attained a higher bond strength when luted on polyacrylic acid-conditioned dentin. In conclusion, smear layer removal, opening of dentinal tubules, and the water content of dentin differently influence the bond strengths and the interfacial characteristics of self-adhesive cement-dentin interface
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
Microhardness of acid-treated and resin infiltrated humane dentin.
No full textObjective. The aim is to determine if superficial or deep dentine microhardness (MH) is affected by different chemical dentine pre-treatments performed for resin bonding.
Methods. Dentine discs of superficial (SD) and deep dentine (DD) were obtained by transversally sectioning the crowns of human third molars. Knoop MH was measured after different treatments: (1) polished up to 4000 grit, (2) polished and etched (37% ortophosphoric acid for 15 s), (3) resin (Single Bond -SB-) infiltrated dentine after acid etching, (4) polished, etched and treated with 5% NaOCl for 2 min, (5) resin infiltrated (SB) after etching and NaOCl treatment. For resin infiltrated surfaces care was taken in order to remove the excess adhesive layer, and obtain infiltrated dentine, by measuring thickness of the sample before resin infiltration and polishing after resin infiltration until obtaining the initial thickness of the sample. Indentations (n = 20) were performed on moist surfaces with a standard Knoop MH tester (20 g, 5 s). Data were expressed in Knoop Hardness Numbers (KHN) and analysed by ANOVA and multiple comparisons (P < 0.05).
Results. Dentine KHN decreased on both SD and DD after acid etching. NaOCl treatment after acid etching did not affect MH on SD, but KHN of DD was towered. Resin infiltration increased KHN but did not recover the initial MH values in both SD and DD.
Conclusions. Treating dentine with either H3PO4 or NaOCl caused marked reduction of its surface hardness and subsequent resin infiltration was not capable to restore it. (c) 2004 Elsevier Ltd. All rights reserved
Effect of thermal cycling on the bond strength of self-adhesive cements to fiber posts
No full textThe aim of this study was to assess the push-out bond strengths of self-adhesive resin cements to epoxy resin-based fiber posts after challenging by thermocycling. Thirty-six single-rooted premolars were endodontically treated, and the post-spaces were drilled to receive RelyX Fiber posts #1. Three self-adhesive resin cements (RelyX Unicem, G-Cem, and Breeze) were used for luting fiber posts. The bonded specimens were either stored for 1 month in a moist field (37°C) or submitted to thermocycling (5,000 times) prior to push-out test. The maximum force required to dislodge the post via an apical-coronal direction was recorded (megapascal). The data were statistically analyzed with two-way ANOVA and Tukey tests (p < 0.05). The factors "luting cement" and "thermocycling" significantly influenced bond strengths. The initial push-out values of RelyX Unicem and Breeze were higher than those of G-Cem. After thermocycling, the bond strength of G-Cem increased and no differences were found between groups. RelyX Unicem and Breeze bond strengths were not affected by the thermal challenge. Thermal cycling and cement type differently influence the bond strengths of self-adhesive resin cements. Self-adhesive cements can represent an option for luting fiber posts into root canal © 2011 Springer-Verlag
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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