1,721,012 research outputs found
A combined RSA and FE study of the implanted proximal tibia: correlation of the post-operative mechanical environment with implant migration
No full textInter-patient evaluation of stresses in proximal implanted tibiae
No full textIn biomechanics finite element analysis (FEA) is still only a comparative tool. To the authors' knowledge, no study has examined multiple tibiae or included patient specific data. Only by constructing finite element models taking into account these parameters in combination with prospective clinical studies can the predictive power of FEA be assessed. The purpose of this study was to evaluate the differences in the predicted stresses and risk ratios observed on the resected surface of models of proximal implanted tibiae created from patient specific data.
Finite element models of four proximal implanted tibiae were analysed. The models were created from quantitative computed tomography (QCT) data. The immediate post-operative situation was modelled by assuming frictionless contact between the tibia and the tibial plateau. Post-operative alignment of the implants were considered in the study. The loads used in the models were equivalent to three times the weight of each patient. A bi-condylar load case was used, in which 60% of the total force was applied on the medial side and 40% on the lateral side. The forces were applied directly on the tibial plateau.
A program called Bonemat, was used to assign the material properties on an element-by-element basis, based on the correlation between QCT data and the material properties of the bone (i.e. apparent density and stiffness). Meshes of linear tetrahedral elements were created in I-DEAS for both bone and implant. Risk ratio values (defined as the Von Mises stress divided by the ultimate compressive strength) on the resected surface of each tibia were examined and compared between all four models. All the analyses were carried out using MARC K7.3.2.
In all four models, a similar overall risk ratio distribution on the surface of interest was observed, with peak values of 319%, 315%, 322% and 327% for patients 1,2,3 and 4, respectively. In all the models, the peak values were found in the portion of cancellous bone supporting the posterior side of the tibial plateau.
For all four tibiae there were areas of bone, particularly around the posterior cruciate cut-out, where the localised risk of failure was high. However, in general, the risk of failure was below 100% over the majority of the resected surface. RSA studies of tibial plateaus have shown that during the first six months after surgery, there is a period of rapid migration. This is widely thought to be due to the implant "bedding in". The findings of this study support this view, as some regions presented considerably high risk ratios. In these regions, the cancellous bone will be crushed and the load redistributed on the resected surface until an equilibrium position is reached. This study has shown that patient specific FE model do demonstrate subtle differences in the predicted stress and risk ratio distributions. This emphasises the importance of moving away from the traditional generic modelling approach to patient specific modelling
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
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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