1,721,144 research outputs found
Composites of polyurethane foams and Ca-Phosphates as scaffold for bone tissue engineering
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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
Bioactivity and Biocompatibility of light-curing resin-modified MTA
No full textObjectives: light-curing resin-modified calcium-silicate cements (lc-MTA) were designed to obtain a fast setting root-end cement for root-end filling. It was hypothesized that lc-MTA are bioactive materials with properties comparable with calcium-silicate Portland cements and ProRoot MTA. Methods: the material was prepared by mixing an amount of calcium-silicate cement, HEMA/TEGMA, canphoroquinone and barium sulphate. The setting time and the solubility were tested according with ISO. Two experimental cements (lc-MTA and MTA) and ProRoot MTA were tested. The lc-MTA was light-cured for 120 seconds. The samples were immersed in simulated body fluid, SBF (DMEM or DPBS). The pH of soaking medium and the Calcium releasing from the cement were tested with ion selective electrodes. The bioactivity was investigated with Raman and ESEM/EDX analyses. The SaOS-2 cell viability on cements was assessed after 3 days of culture by Alamar blue test. Results: the setting time was 2 minutes for lc-MTA, 74 for MTA and 76 for ProRoot MTA. The solubility of lc-MTA was significantly reduced. A complex network of round-shaped precipitates (as sub-micron spherulites), covering the cement surface, mainly composed Ca and P was observed by ESEM/EDX after 24 hours of SBF immersion. Raman confirmed the presence of apatite bands (960 cm-1). Both MTA showed a lower amount of sub-micron spherulites deposits covering cement surface than lc-MTA. All cements exerted no acute toxicity in the cell assay systems. Conclusion: the study demonstrated the early and improved bioactivity of light-curing resin-modified MTA cements. The lc-MTA with very short setting time and adequate mechanical properties expand the range of clinical application of conventional MTA cements. Early in vitro bioactivity makes the lc-MTA cements an attractive alternative to conventional MTA cements as root-end repair materials
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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