1,720,969 research outputs found
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
Quantitative t2: software, application, workflows, phase correction
No full textBibliography: p. 10, 19-20, 44-45, 53, 69-74, 87-90, 100-103, 118-119, 141-143Some pages are in colour
Efficient s-transform techniques for magnetic resonance imaging
No full textBibliography: p. 227-247Some pages are in colou
Real-time voxel-based quantitative t2 mri analysis and applications
No full textBibliography: p. 103-106Many pages are in colour
Magnetic resonance imaging derived biomarkers in multiple sclerosis
No full textBibliography: p. 143-172Several mechanisms contribute to the complex pathophysiology of multiple sclerosis (MS). This calls for biomarkers to characterize the heterogeneity of MS in individual subjects. The advancement in magnetic resonance imaging (MRI) technology over past decades makes it the most attractive biomarker candidate in MS. Texture analysis was applied to quantify subtle abnormalities on the MRI from people with MS. A classical statistical method (gray level co-occurrence matrix) was able to detect a tread yet not significant difference of therapeutic responses between different tissue types. A novel time-frequency based technique (polar Stockwell Transform, PST) was then investigated. The increased PST texture was shown to represent inflammation and demyelination in a murine model of MS. PST texture altered significantly when tissue MRI evolved from normal appearing white matter to MS lesions. It decreased significantly when an active lesion became inactive. This suggests that the PST texture may be a MRI surrogate to characterize subtle and early abnormalities existed in MS tissue. MS is also a neurodegenerative disease in the central nervous system (CNS) affecting both white matter and grey matter (GM). Abnormally decreased signal intensity (black T2, BT2) in the deep GM of MS patients was noted on 1.5 T MRI. Due to the iron deposition phenomenon in its underlying tissue, 3 T MRI was more sensitive to BT2 detection than 1.5 T MRI. A higher correlation was obtained between patient disability and deep GM BT2 measured at 3 T than that at 1.5 T in MS. The association of 3 T BT2 with EDSS was greater than most of the MRI derived indices in MS. The small sample size limits broad conclusions. However, these results encourage further investigation of the clinical significance of BT2 as a biomarker for disability in MS at high field. This thesis provides evidence for proof of concept that the new developed techniques may have potential to become surrogate measures in MS diagnostics and treatment. However, these techniques need to be combined with other MRI matrices in order to obtain an integrated picture of MS
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