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Expressão da Nanoinfiltração na Interface Dentina-Material de Quatro Materiais Retrobturadores
Get PDFBack-Scattered electron imaging for leakage analysis of four retrofilling mateials
No full textO objetivo deste estudo foi avaliar, ex vivo, a nanoinfiltração nos túbulos dentinários, a infiltração linear do nitrato de prata na interface parede de dentina/material retrobturador e a presença de gaps nessa interface em cavidades retrógradas obturadas com 4 materiais retrobturadores. Quarenta e oito canais radiculares de raízes disto-vestibulares de primeiros molares superiores foram instrumentados e obturados. Após a secção de 2mm da porção apical, cavidades retrógradas foram preparadas com pontas de retropreparo ultra-sônica e os dentes divididos aleatoriamente em quatro grupos experimentais (n=10) e dois controles (n=4): Grupo I - MTA Branco; Grupo II – Super EBA; Grupo III - Cimento de Portland; Grupo IV - Sealer 26. Uma semana após os espécimes foram submetidos ao nitrato de prata amoniacal e posteriormente desgastados longitudinalmente até a exposição do material retrobturador. A seguir, os espécimes foram preparados para microscopia eletrônica de varredura, equipada com detectores de imagem de elétrons retroespalhados (backscattered electrons- BSE). No segmento apical-apical foi possível verificar diferença estatisticamente significante entre os grupos do cimento Sealer 26, MTA, Portland e Super EBA (P < 0.05), com maior porcentagem de área nanoinfiltrada para esse último. Para os segmentos apicalmédio e apical-cervical os 4 grupos experimentais apresentaram comportamento similar (P > 0.05 e P > 0.05 respectivamente). Na avaliação da infiltração linear, na interface parede de dentina/material retrobturador, o Super EBA demonstrou maior infiltração, porém sem diferença significativa com os outros 3 grupos experimentais (P > 0.05). Com relação à porcentagem de gaps ao longo dos 3 mm da interface dentina/material retrobturador foi evidenciado ausência de diferenças entre os 4 materiais retrobturadores (P>0.05). Nenhum material selou hermeticamente a retrocavidade, permitindo a ocorrência da nanoinfiltração, sendo que a maior porcentagem de área nanoinfiltrada e nanoinfiltração linear ocorreu no primeiro milímetro da retrocavidade (apico-apical) com maiores valores para o Super EBA.The aim of this study was to evaluate the nanoleakage dentinal tubules, the linear infiltration of silver nitrate in the interface wall dentin/ retrofilling material and the presence of gaps of this interface in retrocavities filled with 4 retrofilling materials. Forty-eight distobuccal root canals of maxillary first molars were instrumented and filled. Following apical resection, retrograde cavities were prepared with ultrasonic points. The samples were randomly divided into two control groups (n=4) and four experimental groups (n=10): Group I - White MTA; Group II - Super EBA; Group III - Portland Cement; and, Group IV - Sealer 26. After one week, the apical 3 mm of each sample was cut and then longitudinally split into two pieces. The specimens were prepared for scanning electron microscopy with backscattered electron analysis. In the apical segment of the sample, higher nanoleakage area was observed for Super EBA, followed by Portland cement, MTA and Sealer 26 (p=0.0054). In the medium and cervical segments, all materials had the same behavior for nanoleakage (p=0.1815 and p=0.1723, respectively). The linear infiltration at the interface dentin wall and retrofilling material was greater for Super EBA when compared to the other groups. Regarding the percentage of gaps along the 3 mm of dentin interface/ retrofilling material was evidenced no differences between the four materials (P> 0.05). According to the results, the tested materials were not able to hermetically seal the cavities. Nanoleakage occurred mainly in the apical segment of the samples (1 mm), and Super EBA showed the highest values. Both the area and linear nanoleakage were lower in the middle and coronal segments for all the samples, regardless the retrofilling material
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
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
Dispelling 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
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
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