1,721,716 research outputs found
Kalimat al-mutarjim (Prefazione del traduttore) li "Fī al-ṭariq ilā Bagdād, al-falsafa, al-‘ilm, al-ṭibb wa al-intišār al-fikrī, fī al-islam bayna al-qarnayn al-ṯāmin wa al-ṯāni ‘ašar, C. Martini Bonadeo"
No full textIntroduzione alla mia traduzione del volume "Sulla via di Bagdad di C. Martini Bonadeo (Tipografia veneta 2012)
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
THE P2Y-LIKE PURINERGIC/CYSTEINYL- LEUKOTRIENE RECEPTOR GPR17 AS A TARGET FOR BRAIN REPAIR IN NEURODEGENERATIVE DISEASES
No full textVariations 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
The mammalian target of rapamycin (mTOR) controls oligodendrocyte maturation by fine-tuning the activity of GPR17 receptor via G protein-coupled receptor kinases.
No full textBackground and Purpose - In the adult central nervous system (CNS), oligodendrocyte precursor cells (OPCs) dispersed throughout the parenchyma serve as a primary source of myelinating cells in demyelinated lesions. The Gi-protein-coupled receptor GPR17 is activated by both uracil nucleotides (e.g. UDP-glucose) and cysteinyl-leukotrienes (e.g. LTD4). We previously reported that GPR17 (i) is transiently expressed by early OPCs (ii) its activation by endogenous ligands promotes OPC differentiation1, and that, (iii) its forced over-expression at late differentiation stages inhibits cell maturation, suggesting that the receptor needs to be down-regulated to allow terminal OPC maturation. Physiologically, GPR17 down-regulation may occur through agonist-induced receptor phosphorylation via G-protein coupled receptor kinases (GRKs)2, and may, in turn, be controlled by the mTOR pathway, that indeed plays a pivotal role in oligodendrocyte maturation3. Here, we used primary OPC cultures to investigate the mechanisms underlying GPR17 down-regulation/desensitization. Their characterization is quite important, since alterations leading to prolonged GPR17 expression in OPCs may contribute to the limited remyelination observed in demyelinating diseases.
Methods and Results - To assess whether GPR17 desensitization occurs through agonist-induced receptor phosphorylation via G-protein coupled receptor kinases (GRKs), OPCs were pre-treated with GPR17 ligands for different time periods and GPR17 ability to inhibit forskolin-induced cAMP formation was measured with a cAMP assay. Through this assay, we demonstrated a loss of GPR17 responsiveness after prolonged exposure to both UDP-glucose and LTD4. Moreover, we also showed that the same agonists induce the direct physical association of GPR17 with GRK2, which in turn phosphorylates the receptor, suggesting a role for GRK2 in GPR17 regulation. Interestingly, we also demonstrated that inhibition of the mTOR pathway by rapamycin determines a significant reduction of GRK2 levels, with parallel increases in GPR17 expression and strong impairment of OPC maturation.
Conclusions - Globally, these data suggest that dysregulation of the pathways controlling GPR17 desensitization leads to aberrant GPR17 overexpression, which, in turn, may prematurely block OPC differentiation at a pre-immature stage. New pharmacological or biotechnological strategies able to re-normalize GPR17 function in demyelinating diseases will help implementing the reparative potential of the OPCs that are still present in the adult CNS.
References
[1] M. Fumagalli, S. Daniele,D. Lecca, P.R. Lee, C. Parravicini, R.D. Fields, P. Rosa, F. Antonucci, C. Verderio, M.L. Trincavelli, P. Bramanti, C. Martini, M.P. Abbracchio, Phenotypic changes, signaling pathway, and functional correlates of GPR17-expressing neural precursor cells during oligodendrocyte differentiation. J Biol Chem. 286(12):10593-604, 2011.
[2] S. Daniele, M.L. Trincavelli, P. Gabelloni, D. Lecca, P. Rosa, M.P. Abbracchio, C. Martini, Agonist-induced desensitization/resensitization of human G protein-coupled receptor 17: a functional cross-talk between purinergic and cysteinyl-leukotriene ligands. J Pharmacol Exp Ther. 338(2):559-67, 2011.
[3] W.A. Tyler, N. Gangoli, P. Gokina, H.A. Kim, M. Covey, S.W. Levison, T.L. Wood, Activation of the mammalian target of rapamycin (mTOR) is essential for oligodendrocyte differentiation. J Neurosci. 29(19):6367-78, 2009
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