1,720,959 research outputs found
Lateral Calcaneal Artery Flap: A Reliable Option for Hindfoot Soft Tissue Defect Coverage
No full textNilesh Ghelani, Sankit Shah, Chandni Joshi,Ashishkumar Hadiyal,Shukan Kapadia, Darshil Rajgo
Method for Characterising and Quantifying Volumetric Edge-Wear in Ceramic-on-Ceramic Hip Anthroplasty Devices
Get PDFMethod for Characterising and Quantifying Volumetric Edge-Wear in Ceramic-On-Ceramic Hip Arthroplasty Devices
Get PDFThe number of primary total hip arthroplasty (THA) surgeries has been increasing worldwide over the last decades reaching over 200 per 100,000 population with a high degree of variability between countries[1-3]. National Joint registry 2017 report mentions that in the UK during the last decade, 711,765 primary surgeries have been carried out in comparison to 80,042 revision surgeries to replace joints that have failed either prematurely or at the end of their useful life[1]. The life expectancy of a hip prosthesis is commonly expected to be 15-20 years.
Of all current commonly used bearing surface combinations,the use of fourth generation ceramic-on-ceramic bearings have proved to be very efficient[4]and has grown in popularity for primary hip surgery in the decadepreceding 2017[1]. This is due to the low reported wear volumes associated with all ceramic bearings [5]as well as the fact that ceramic debris being bio-inert overcomes the commonly reported issues of systemic cobalt chromium ion concentration as reported in metal-on-metal bearings [6, 7]and issues of osteolysis induced by polyethylene wear debris in metal-on-UHMWPE [8, 9]. The interest in ceramic-on-ceramic is elevated also due to significant improvements in material properties and manufacturing process [10]. However, the ceramic-on-ceramic hip prosthesis are reported to squeak in-vivo [11, 12]which appears to be linked to edge-loading [13]. Also, it has been reported that an unusual stripe pattern of wear can occur in some retrieved acetabular cup liners [14]and it has further been postulated that this is caused by cup liner edge loading [15]. The combined measurement challenge of wear occurring at the edge of the acetabular liner of a low-wearing ceramic-on-ceramic prosthesis is therefore considerable.
Various wear measurement methods have been developed to measure wear in hip prostheses[12, 16-18], yet current recognised industrial practice regarding in vitro measurement of wear for hip joint prostheses involves either gravimetric assessment or co-ordinate measurement [19].Due to the considerable challenge in geometrical characterization of edge wear, current literature regarding the assessment of edge-wear in acetabular cup liners has been confined to in-vitro simulator studies and gravimetric measurement to assess wear volumes. Geometric characterisation of wear is essential in determining the contact conditions during gait and subsequent calculation of point and magnitude of the maximum stress condition. It is, therefore, vital that a robust and reliable method for geometric measurement and analysis of edge wear is created.
Current methodologies for assessing wear on acetabular cups have focused on quantifying the amount of material loss on the bearing surface. The bearing surface is constituted by well-defined geometry and surface characteristics. As such methods are able to estimatethe unworn surface and determine the amount of material loss. However, the main limitation of these methods was that wear could only be estimated on the well-defined spherical geometry of bearing surface. Hence, when edge wear is present at the boundary between the bearing surface and outer cup geometry it is normally thresholded during analysis process when using current methods. This can potentially underestimate the amount of wear present on acetabular cups.
This study provides details of the requirements and methodologies for the measurement and analysis of edge wear in ceramic-on-ceramic liners. Two methodologies have been developed based on measurements using a coordinate measuring machine and a roundness measuring machine. Both methods havebeen evaluated using ceramic liners tested in vitro under edge loading conditions, and the volume loss is compared to gravimetric measurements. The results show that both methods have the required resolution to measure volume loss of less that 1mm3and are thus capable of providing a volume loss estimation for ceramic-on-ceramic acetabular liners
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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