1,720,973 research outputs found
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
Expression pattern and distribution of the oligodendroglial receptor GPR17 in Experimental Autoimmune Encephalomyelitis, a mouse model of Multiple Sclerosis
No full textBackground and Purpose - GPR17 is a G protein-coupled receptor activated by both uracil nucleotides and cysteinyl-leukotrienes, two families of mediators involved in inflammatory responses of Central Nervous System (CNS)1. Under physiological conditions, GPR17 is expressed in Oligodendrocyte Precursor Cells (OPCs) that also express the early marker NG2, reaches its maximal peak of expression in immature oligodendrocytes and is progressively downregulated during terminal maturation. Moreover, activation of the receptor by its endogenous ligands promotes whereas antagonists or RNA interference approaches impair OPC differentiation2,3. In brain, significant up-regulation of GPR17 was found at injury sites both in a rodent model of brain ischemia and after an acutely induced demyelination2,4.
The present work was aimed at characterizing the expression pattern and distribution of GPR17 in mouse spinal cord, both under physiological conditions and in Experimental Autoimmune Encephalomyelitis (EAE), a murine model of Multiple Sclerosis.
Methods and Results – EAE was induced in eight-week-old female C57/BL6 mice immunized with MOG35-55/CFA and treated with pertussin toxin (PTX) at 0 and 2 days post-immunization (DPI). Disease severity was monitored daily. Animals were sacrificed at 21 DPI in order to perform immunohistochemistry (IHC) analysis and semiquantitative real-time PCR (qRT-PCR) analysis.
As already described for brain, IHC analysis revealed that, also in spinal cord, GPR17 specifically decorates a subset of early OPCs both in grey and white matter. After EAE induction, both the total number of mature CC1-positive, and GPR17-positive cells was reduced, whereas the number of NG2-positive cells was increased, suggesting disease-induced recruitment and proliferation of early progenitors.
Interestingly, despite the decrease in the number of GPR17-positive cells, qRT-PCR analysis showed an up-regulation of GPR17 in the spinal cord of the same group of mice, and this seems to be related to their clinical score and to the relative increased levels of IL-1β, used as an inflammatory marker.
Conclusions - Based on our data, we hypothesize that GPR17 is up-regulated in the disease to counteract demyelination, but this response is dysregulated at a post-transcription level, likely due to the inflammatory environment, resulting in impaired repair and eventually contributing to the disease. Characterization of the molecular defects of GPR17 in EAE will help re-establishing its correct function in remyelination and foster the identification of new pharmacological strategies to enhance the reparative potential of OPCs in the adult brain
A structure theory for two-dimensional translation planes of order q^2 that admit collineation groups of order q^2
No full textDispelling 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
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