1,720,972 research outputs found
Irreversible cardiac failure with intraventricular thrombosis: A novel technique of paracorporeal biventricular assist device implantation with ventricles excision
Full text linkAnalysis of early and long-term outcomes of acute type A aortic dissection according to the new international aortic arch surgery study group recommendations
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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
Left ventricle assist devices and drivelines infection incidence: a single-centre experience
Full text linkVariations 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
Risk stratification of severe aortic stenosis according to new guidelines: Long term outcomes
Full text linkBackground: Current ESC and ACC/AHA guidelines for the management of valvular heart disease assign a class Ia indication for aortic valve replacement (AVR) only to patients with symptomatic severe aortic valve stenosis and asymptomatic patients with depressed left ventricular ejection fraction (LVEF <50%) or positive exercise test. We examined the long-term outcomes for patients undergoing AVR for aortic stenosis over a 11-year period at our institution compared to current international guidelines for AVR. Methods: Patients who had undergone isolated AVR for severe aortic valve stenosis between January 2001 and December 2012 were selected. The population was divided into subgroups based on preoperative LVEF (< or ≥50%) and on presence/absence of symptoms (NYHA =I or ≥II, respectively). Results: We identified 607 patients with a median follow-up (FU) time of 5.75 years (IQR 3.24–8.00 years). The presence of symptoms did not have a significant impact on cardiovascular mortality (P=0.201). Patients with LVEF <50% displayed a higher long-term cardiovascular mortality rate (P=0.015). Multivariate analysis showed that preserved LVEF was a protective factor for asymptomatic patients (P=0.021), while preoperative LVEF did not affect the mortality rate in symptomatic patients (HR 0.88; 95% CI, 0.54–1.44). Correspondingly, asymptomatic patients with reduced LVEF were found to be at a higher risk of long-term mortality compared to the other groups (P=0.011). The only other independent risk factor for death was age (HR 6.46; 95% CI, 2.22–18.76). Conclusions: According to our data, current international class I indications for symptomatic patients ensure good long-term survival, while class I indications for asymptomatic patients with reduced LVEF are associated with poor long-term survival. Our results suggest that early surgery should also be considered also for asymptomatic patients with preserved LVEF, particularly in cases of very low operative risk. © Journal of Thoracic Disease. All rights reserved
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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