1,720,978 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
Segregazione superficiale in elettrodi a base di ossidi misti di Ir e Co : effetto sull’evoluzione catodica di idrogeno
No full textBrain arachidonic acid metabolic pathway is altered during cuprizone-induced demyelination
No full textObjectives: Multiple sclerosis (MS) is characterized by recurrent and progressive demyelination/remyelination cycles which result in development of scleroses (scars) in white and gray matter of CNS, axonal damage and neuronal loss. There is no cure for MS, and only symptomatic treatments are available.1 Chronic cuprizone exposure produces progressive demyelination in mice brain which reverses upon its removal from the diet.2 Since there is limited evidence of altered arachidonic acid (AA) metabolism in MS, we hypothesized that cuprizone exposure would alter the expression of genes involved in AA metabolism, and that these genes represent potential therapeutic targets.
Methods: Adult C57B16 mice were exposed to cuprizone for 6 weeks and then returned to a normal diet. Demyelination was assessed by histochemistry and magnetic resonance imaging. Real-Time PCR and western blotting were used to determine gene and protein expression, respectively, of critical enzymes involved in AA metabolism.
Results: We demonstrated that the Magnetization Prepared Rapid Gradient Echo (MPRAGE) is a useful MRI technique to assess quantitatively structural changes in myelin rate in the corpus callosum during cuprizone exposure. Histochemistry with the myelin stains Black Gold and Fluoromyelin demonstrated that frank demyelination and influx of glial cells into the corpus callosum begins at week 3 and peaks at week 5. However, a decrease in myelin and oligodendrocyte markers, myelin basic protein (MBP) and 2,3-cyclic nucleotide 3-phosphodiesterase (CNPase), was evident at week 1. Increased expression of CD11b and glial acidic fibrillary protein (GFAP), evidence of activated microglia and astrocytes, was also observed at week 1. Coincident with these early changes, we found an increase in cyclooxygenase (COX)-2 that persisted throughout the demyelination process as well as lipoxygenase 15-LO which was increased at week 1 and peaked in the height of frank demyelination suggesting that these AA metabolism genes are either involved in or respond to the earliest sign of demyelination. Moreover, western blotting analysis showed that 15-LO protein levels, peaked in the height of frank demyelination. Both gene and protein expression of 5-LO was not significantly changed during the early stages of demyelination but it peaked during week 5, when glial markers and frank demyelination also reached their peak of expression. While expression of 12-LO was not consistently increased during demyelination, increased 12-LO expression was observed during the remyelination, suggesting a role for this isoform in the recovery process. The expression cPLA2 and sPLA2 also increased at the peak of frank demyelination, while Ca2+-independent iPLA2 expression was not changed.
Conclusions: Multiple enzymes involved in AA metabolism are altered in the cuprizone model of MS suggesting that COX- and LO- derived AA metabolites are involved in demyelination and remyelination. Moreover, MPRAGE is a sensitive and non invasive method that allows to arrange longitudinal studies and to create a bridge between animal and human studies. These data may help to develop new biomarkers and therapeutic targets to treat demyelinating diseases.
References
1. Franklin RJ, Ffrench-Constant C. Nat Rev Neurosci. 2008;9(11):839–55.
2. Ludwin SK. Ann Neurol 1994;36(Suppl):S143–5. Review
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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