1,720,973 research outputs found
Fracture Strength and Failure Modes of Endodontically Treated Premolars Restored with Compact and Hollow Composite Posts Subjected to Cyclic Fatigue
Full text linkPhysical and mechanical properties of continuous carbon or glass fiber reinforced endodontic posts are relevant to increase the retention and resistance of the tooth‐restoration system. Hollow posts have been recently designed for delivering the luting cement through the post hole, thus enhancing the post‐dentin interface by reducing the risk of air bubbles formation. Methods: Three type of endodontic posts, a carbon fiber hollow post, a glass fiber hollow post and a compact glass fiber post were investigated. Mechanical properties of these posts were assessed through bending tests. Teeth were subjected to fatigue cycling and the strength of restored teeth was detected through static tests. Failure modes were investigated through optical and scanning electron microscopy. Results show that composite posts increase the mechanical stability by more than 100% compared to premolars restored with particulate composite. Carbon fiber posts retain the highest strength (1467 N ± 304 N) among the investigated post and core restoration, but an unfavorable type of fracture has been observed, preventing the tooth re‐treatment. Instead, more compliant posts (i.e., glass fiber reinforced composite, providing a strength of 1336 N ± 221 N), show a favorable mode of fracture that allows the re‐treatment of teeth in the case that failure occurs. Glass fiber hollow posts show a good trade‐off between strength and a favorable type of fracture
A Preliminary Analysis of the Effects of Process Parameters on the Impact Resistance of 3D Printed PETG and HIPS
No full textAdditive manufacturing (AM) allows the development of novel and customized products with tailored properties. However, the application of extrusion-based AM techniques (i.e., fused deposition modeling – FDM) in the design of functional parts is often limited because of the poor mechanical performance as a consequence of the nature of the process to build the object in a layer-by-layer fashion. In the current study, the impact resistance of the 3D printed polyethylene terephthalate glycol-modified (PETG) and high impact polystyrene (HIPS) was evaluated as a function of three printing parameters (i.e., printing temperature, layer height and line width). Izod-type test specimens were fabricated and analyzed according to the ASTM D256. The contribution of each factor was properly analyzed. The results also indicated that the printing temperature was the most significant parameter for the impact resistance of 3D printed PETG and HIPS. The obtained findings may be considered as valid only within the limit of parameters and ranges investigated in the current study
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
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
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
Hydrodynamic boost: a novel re-entry technique in subintimal angioplasty of below-the-knee vessels
No full textTo describe the hydrodynamic boost (HB) technique and report our preliminary results with this technique in the subintimal angioplasty of below-the-knee vessels.
HB was used in 23 cases (14 males, mean age 73 +/- 12 years) of critical limb ischemia, with long chronic total occlusion of tibial arteries extended to the ankle level. The operator performs a manual injection of diluted contrast dye through a 4 F catheter into the subintimal space, close to the patent true distal lumen, in order to achieve a tear in the intimal flap and a connection with the true lumen.
In 19/23 (83 %) cases, the HB was effective in creating a connection between the subintimal space and the true distal lumen and it was possible to advance a wire and to conclude the procedure. In 4/23 (17 %) lesions, the HB failed and the procedure was successfully completed by retrograde approach. No major complications occurred. Mean length between catheter tip and re-entry point was 8 +/- 5 mm.
HB seems to be a feasible, safe and effective re-entry technique in distal below-the-knee vessels. This method represents an easy option for re-entry that extends the possibility of antegrade approach to obtain a successful revascularization.
In subintimal angioplasty of below-the-knee vessel re-entry can represent a challenge.
Inability to re-enter may determine the failure of the revascularization procedure.
HB is a novel re-entry technique feasible in distal below-the-knee vessels.
HB may increase the success rate of antegrade approach.
In case of failure, retrograde approach remains feasible
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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