1,720,974 research outputs found
Influence of various application systems on the amount of extruded irrigant in simulated immature teeth with regard to gravity: An ex-vivo study
No full textBackground: Gravity impact has been mainly evaluated in mature teeth related to debris extrusion, even though it may affect the amount of apically extruded irrigant. In the literature the influence of gravity on the amount of apically extruded irrigant in immature teeth has been studied by a 45o inclined plate to mimic the position of the maxillary teeth and 90o for the mandibular teeth. However, patients are positioned horizontally in the dental chair while treatment. There is no study in the literature testing the horizontal position to mimic the clinical settings realistically. Aim: The aim of this study was to evaluate the influence of various irrigation systems on the amount of extruded irrigant in simulated immature maxillary and mandibular teeth irrigated in vertical and horizontal positions. Materials and Methods: Twenty-five maxillary central incisors with an apical opening of 1.3 mm in diameter were included. Irrigation procedures were performed with EndoVac, closed-ended, and open-ended needles using a VATEA peristaltic pump. The amount of apically extruded irrigant was determined using a microbalance. Statistical analysis was performed using the Kruskal-Wallis test. Results: The EndoVac system caused almost no irrigant extrusion in all tested positions (P > 0.05); however, closed-ended and open-ended needles extruded more irrigant in a mandibular vertical position compared to maxillary vertical (P < 0.05) and maxillary horizontal positions (P < 0.05). Open-ended needles extruded the highest amount of irrigant. Conclusions: The EndoVac macrocannula is a more reliable and safer irrigation system as it prevents irrigant extrusion independent of the position of the tooth
A comparative study of root canal preparation with HERO 642 and Quantec SC rotary Ni–Ti instruments
No full textAim The purpose of this study was to compare several parameters of root canal preparation using two different rotary nickel-titanium instruments: HERO 642 (MicroMega, Besancon, France) and Quantec SC (Tycom, Irvine, CA, USA). Methodology Fifty extracted mandibular molars with root canal curvatures between 20 degrees and 40 degrees were imbedded into a muffle system. All root canals were prepared to size 45 (Quantec SC), or 40 (HERO 642), respectively. The following parameters were evaluated: straightening of curved root canals, postoperative root canal diameter, safety issues (file fractures, perforations, apical blockages, loss of working length), cleaning ability, and working time. Results Both Ni-Ti-systems maintained curvature well: the mean degree of straightening was 2.3 degrees for Quantec SC and 1.6 degrees for HERO 642. Most procedural incidents occurred with Quantec SC instruments (five fractures, three apical blockages, eight cases of loss of working length), HERO 642 preparation resulted in three blockages and one perforation. Following preparation with HERO 642, 63% of the root canals showed a round, 24% an oval, and 17% an irregular diameter; Quantec SC preparations resulted in a round diameter in 24% of the cases, oval shape in 29%, and irregular cross-section in 47% of the cases. Mean working time was shorter for HERO 642 (52 s) than for Quantec (117 s). Cleanliness of the root canal walls was investigated under the SEM using a five-score system for debris and smear layer. For debris HERO 642 achieved better results (80% scores 1 and 2) than Quantec SC (76%). The results for smear layer were similar: cleaner root canal walls were found after preparation with HERO 642 (53% scores 1 and 2), followed by Quantec SC (41%). Conclusions Both systems respected original root canal curvature well and showed good cleaning ability; Quantec SC showed deficiencies in terms of safety
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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