1,720,964 research outputs found
In vitro evaluation of cyclic fatigue of rotary Ni-Ti instruments
No full textAim. The aim of this study was to evaluate, in vitro cyclic fatigue of Ni-Ti rotary instruments through the use of an experimental model.
Methods.The Ni-Ti rotary instruments evaluated were 18 ProFile 25/.06 (Maillefer-Tulsa, USA), 18 K3 25/.06 (Sybron Endo, Orange), 18 Twisted File 25/.06 (Sybron Endo, Orange). The analysis of resistance to cyclic fatigue was performed using an experimental model with angles of 45 °, 60 ° and 90 °. Finally an endodontic handpiece VDW Gold Series (Dentsply, Italy) was fixed in a vise. The working parts of the instrument, equal to 16 mm, was inserted into the hollow cylinder with a length of 9 mm, measured using a caliper. In order to estimate the time of fracture was filmed using a Sony Full HD (1080) 10.2 megapixels. The statistical test was conducted using ANOVA and t-student to analyze two groups of instruments at the same angle. Null hypothesis (H0): The three different types of Ni-Ti have the same resistance to cyclic fatigue flexor. Alternative hypothesis (Ha): At least one of the three instruments is resistant to cyclic fatigue flexor than that of others. The significance of both tests has been put at 5% (p ≤ 0.05).
Results. Twisted File and ProFile to 45 ° and 60 ° showed a highly significant resistance to cyclic fatigue (p 0.05), but the systematic Twisted File was statistically significant compared to the other two (p <0.0001).
Conclusions. The statistical analysis showed a good resistance to cyclic fatigue with regard to systematic ProFile and Twisted File, by contrast, the systematic K3 was found to be less than 45 °, 60 ° and 90 °
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
Increases of intracanal and root surface temperatures during the obturation of canal using the E&Q Master System and the System B.
No full textObjectives: The purpose of our study is to assess the increases of intracanal and root surface temperatures during the obturation of canal system using the E&Q Master System and the System B.
Materials and methods: A split-tooth model was built. To measure the temperature, 6 grooves for the placement of thermocouples were made in the buccal half of the model. On the mesial side, three grooves were made at 2, 4 and 6 mm from the anatomical apex and were extended to the root surface, while on the distal side three grooves were made at 2, 4 and 6 mm up to the intracanal portion. In each of these grooves was inserted a type T thermocouple (Copper-Costantana) with a diameter of 0.076 mm. 40 canal obturations were done: 20 using the E&Q Master System and 20 using the System B, set at 250 °C, both with plugger FM increased to 3.5 mm from WL. The temperatures were recorded at 1 s intervals for a period of 200 s.
Results: During the continuous wave obturation technique two peaks in temperature occurred, the first caused by the plugger in the canal, the second during the separation phase. In the E&Q Master System the highest increases were recorded in the thermocouple N.6, which reported average increases of 6.30 °C, while the lowest were recorded in the thermocouple N.1, which reported a value of 2.11 °C. In the System B group the highest increases were recorded in the thermocouple N.6, which reported average increases of 2.80 °C, while the lowest were recorded in the thermocouple N.1, which reported a value of 0.4 °C.
Conclusions: Analysis of the obtained results showed that both systems allow us to get a good thermal mass increase of gutta-percha. Results show that the use of E&Q Master System and System B, in vitro, appears to cause a dangerous increase in temperature along the surface of the root that may create iatrogenic injury
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
- …
