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In vitro evaluation of a manganese chloride phantom-based MRI technique for quantitative determination of lumbar intervertebral disc composition and condition
No full textThe application of MRI as a non-invasive, quantitative tool for diagnosing lumbar intervertebral disc degeneration is currently an area of active research. The objective of this study was to examine, in vitro, the efficacy of a manganese chloride phantom-based MRI technique for quantitatively assessing lumbar disc composition and degenerative condition. Sixteen human lumbar discs were imaged ex vivo using T2-weighted MRI, and assigned a quantitative grade based on the relative signal intensities of nine phantoms containing serial concentrations of manganese chloride. Discs were then graded macroscopically for degenerative condition, and water and uronic acid (glycosaminoglycan) contents were determined. MRI ranking exhibited significant and strong negative correlation with nucleus pulposus uronic acid content (r = −0.78). MRI grades were significantly higher for degenerate discs. The technique described presents immediate potential for in vitro studies requiring robust, minimally invasive and quantitative determination of lumbar disc composition and condition. Additionally, the technique may have potential as a clinical tool for diagnosing lumbar disc degeneration as it provides a standardised series of reference phantoms facilitating cross-platform consistency, requires short scan times and simple T2-weighted signal intensity measurements.Lachlan J. Smith, Andrew P. Kurmis, John P. Slavotinek, Nicola L. Fazzalar
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
Considering the Value of Imageless, Accelerometer-Based, Intraoperative Mini-Navigation Systems in Contemporary Primary Total Knee Arthroplasty
No full textGender differences in unintended anterior pelvic roll during primary THA in the lateral position
No full textAbstract Background Fundamental morphologic differences between male and female pelvises are historically recognised. Despite this, little consideration has been given as to whether or not conventional positioning supports used for primary total hip arthroplasties (THAs) performed in the lateral position do an equally effective job of maintaining the intended set up position when comparing genders. Given that recent research has highlighted that unintended pelvic roll occurs commonly during hip surgery, and that such movement may have a mechanically-deleterious consequence upon final construct performance and complication rates, this study was undertaken to explore the differences in pelvic roll between genders. Methods The output of a high-precision, commercially-available, imageless intra-operative navigation system was prospectively-collected for 85 consecutive patients undergoing unilateral, primary THAs. These data were separated by gender and were utilised to determine differences in pelvic movement around a central sagittal axis. Results Demographic data were similar between genders, with no between-group differences in mean BMI (p = 0.09) or indication for surgery (p = 0.66), however participating males (mean 68.04) were slightly younger than females (mean 73.31). The mean anterior pelvic roll for females was 9.50°, and for males 8.68°. There were no statistically significant independent correlations observed between gender (p = 0.21) and pelvic roll. Conclusion The findings of this novel study do not suggest gender differences in the magnitude of unintended, intra-operative, anterior roll, even when corrected for BMI and surgical indication. Average roll of ~ 9° was demonstrated across both groups. An awareness of such positional change during THA surgery may reduce potentially-avoidable post-operative complications
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