1,721,071 research outputs found
Synthesis of fragments of Salmonella typhi capsular polysaccharide and their zwitterionic analogues
No full textGoing 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
Sicurezza in analgesia post-operatoria: dati osservazionali preliminari su eventi di depressione respiratoria post-operatoria.
No full textFluorinated poly(butylene terephthalate): Preparation and properties
No full textFluorinated poly(butylene terephthalate) (PBT) can be easily prepared using a telechelic perfluoropolyether (PFPE) as a comonomer. The functional groups of the PFPE react completely with other monomers, but the distribution of the PFPE blocks is not homogeneous and in the final polymeric material there is a significant fraction of PFPE bonded to very short segments of polyester. Due to the very poor miscibility of PFPE and PBT, the PFPE is present as a separate phase dispersed in an almost pure PBT matrix. Accordingly, both thermal and mechanical properties of PBT are little affected by the PFPE. The presence of PFPE induces a slight improvement on the fracture resistance and on surface properties such as wear resistance and coefficient of friction. © 1994 John Wiley & Sons, Inc. Copyright © 1994 John Wiley & Sons, Inc
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
Impact of previous cardiac operations on patients undergoing transapical aortic valve implantation: Results from the italian registry of transapical aortic valve implantation
No full textObjectives: Redo cardiac surgery has an increased risk of morbidity and mortality when compared with the initial operation. The aim of this study was to assess the impact of previous cardiac operations on patients undergoing transapical aortic valve implantation (TA-TAVI). Methods: We analysed data from 566 patients included in the Italian Registry of Transapical Aortic Valve Implantation who underwent TA-TAVI implantation with the Sapien valve (Edwards Lifesciences, Irvine, CA, USA) from April 2008 through May 2011. Of these, 110 patients (19.4%) had already undergone at least one previous cardiac operation with opening of the pericardium (group R) while for 456 patients (80.6%) TA-TAVI was the first cardiac procedure (group F). Data were prospectively collected at each of the 20 participating centres and then sent to a central database for storage and analysis. Results: Preoperative logistic EuroSCORE was higher in group R (35 ± 18.6 vs. 23.5 ± 11.9%; P < 0.001). Hospital mortality occurred in eight (7.2%) and 36 (7.9%) patients in groups R and F, respectively (P = 0.8). Mean follow-up was 10.4 ± 7.9 months (range: 1-34). Overall 2-year Kaplan-Meier survival was 64.2 ± 9.8 and 75.4 ± 3.5% in groups R and F, respectively (P = 0.69). Incidence of operative complications, postoperative bleeding, pacemaker implantation, myocardial infarction and stroke did not show statistically significant differences between groups. The univariate analysis showed that arterial hypertension, logistic EuroSCORE, porcelain aorta, left ventricular ejection fraction and previous percutaneous coronary interventions were significantly associated with 30-day mortality in group R. Conclusions: According to our data, patients undergoing TAVI with previous cardiac operations have a higher preoperative risk profile but have similar outcomes when compared with patients undergoing a first operation. In these subset of patients, TAVI is a promising therapeutic option. © The Author 2012. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved
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