1,720,996 research outputs found
“La protezione pulpodentinale in Conservativa per mezzo di materiali intermedi”.
No full textLa polpa dentale risulta esposta a sollecitazioni di vario tipo e di vario grado sia nel corso della vita di relazione, sia soprattutto durante varie attività specialistiche odontoiatriche. Nel presente contributo viene presentata una ampia rivista della letteratura su: fisiologia, fisiopatologia e patologia del tessuto pulpare a seguito di stimolo; natura e forza degli stimoli che possono pervenire alla polpa (termici, elettrici, chimici, iatrogeni); materiali intermedi che interposti tra ricostruzione e tessuto dentinale possono annullare o diminuire l'intensità degli stimoli (lacche, vernici, liners, sottofondi a base di ossido di zinco eugenolo, ZOE rinforzati, ossifosfati di zinco, policarbossilati, cementi vetroionomeri). Vengono inoltre presentate tutte quelle attività preventive del danno che può svilupparsi a seguito della preparazione cavitaria o delle manovre di rifinitura e lucidatura degli amalgami. Una sezione del lavoro è particolarmente dedicata alle caratteristiche termiche dei tessuti duri dentali al fine di comprendere quanto questi possano fungere da isolanti o dissipatori del calore proveniente dall'esterno. Particolare enfasi è infine attuata nei confronti dell'efficacia del raffreddamento spray aria-acqua dipunte e frese montate su turbine e micromotori, maggiore causa di danno iatrogenico
Chemistry, tissue and cellular distribution, and developmental profiles of neural sphingolipids
No full textSphingolipids constitute a class of lipids characterized by the presence of a long chain aminoalcohol (sphingoid base) and are particularly abundant in the nervous system. They include simple molecular species(sphingosine - or sphinganine -, sphingosine-1-phosphate, ceramide, ceramide-1-phosphate), and the ceramide containing complex sphingolipids (sphingomyelin, cerebrosides, sulfatides, neutral glycosphingolipids, acidic glycosphingolipids-gangliosides-, etc.). First, the chemical details are reported of both the naturally occurring sphingolipids, mostly present at the level of cellular membranes, and the synthetic sphingolipids, derivatives of sphingolipids, and mimetics of sphingolipids, that are extremely useful for biological investigations. Owing to the compositional complexity of sphingolipids, the analytical approaches employed for their detection, structural characterization, quantification, and “in situ” detection, are also briefly reviewed, in order to provide a basic and rationale background to investigators interested in the field. Then, the compositional profiles of sphingolipids in the nervous system of different animals, with particular emphasis to humans, are described, illustrating the analogies and differences, with regard to regional, cellular and subcellular localization of the individual sphingolipid species, with special attention to gangliosides, that display the wider array of composition. The differences in the long chain base and fatty acid composition, together with those in the saccharide composition in glycosphingolipids are also outlined, as a necessary chemical premise to understand the intricacy of the related metabolic pathways and to acknowledge the specifically distinct features of their functional implications. Finally, the developmental profiles of sphingolipids in the course of neural development and ageing in the different animals are described, illustrating common trends and peculiar differences among animals
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
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
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