1,721,013 research outputs found
Results of atrial fibrillation ablation during mitral surgery in patients with poor electro-anatomical substrate
No full textBACKGROUND AND AIM OF THE STUDY: Enlarged (> 50 mm) atria, longstanding (> 5 years) persistent atrial fibrillation (AF) and age > 70 years are considered predictive of recurrent AF following surgical ablation. The electrophysiological and clinical outcome after AF-ablation was evaluated in high-risk patients undergoing concomitant procedures. METHODS: Between January 2005 and January 2009, a total of 45 patients who complied with the three major predictors of failure, but who had undergone AF ablation ('left + right bipolar radiofrequency Maze') during concomitant mitral surgery were followed up. Freedom from AF, atrial flutter (AFL) and atrial tachycardia (AT), without anti-arrhythmic therapy (discontinued at the sixth month) was the primary endpoint. Survival, freedom from AF/AFL/AT with anti-arrhythmic therapy, early events during post-ablation blanking period, freedom from congestive heart failure (CHF) and from re-hospitalization, and changes in NYHA functional class were registered. RESULTS: Postoperatively, 18 patients (40%) showed sinus rhythm (SR) at admission to the intensive care unit, while 16 (26%) showed junctional rhythm and five (11%) required definitive pacemaker. Eleven of the 40 patients (28%) were discharged without a pacemaker, and experienced early events during the post-ablation blanking period. After a mean of 21 +/- 14 months' follow up, the actuarial survival was 88 +/- 7%. The prevalence of SR at six, 12, and 18 months was 74%, 64%, and 64% respectively. Freedom from AF/AFL/AT was 54 +/- 10% without anti-arrhythmic medications, and 51 +/- 9% with such drugs. Freedom from CHF was 85 +/- 6%, and significantly better in SR patients (94 +/- 6%) than in AF patients (69 +/- 13%; p = 0.018). Freedom from rehospitalization was 75 +/- 8%, and better in SR patients (94 +/- 6%) than in AF patients (37 +/- 14%; p = 0.0001). Accordingly, when compared to AF patients, the NYHA class was significantly ameliorated in SR patients at both six months (1.4 +/- 0.6 versus 2.7 +/- 0.9) and at the final follow up control (1.2 +/- 0.5 versus 1.9 +/- 0.7; p < 0.0001). The E/A wave recovered in 22 (85%) of the SR patients. CONCLUSION: AF ablation during mitral valve surgery achieves good electrophysiological results, even in patients traditionally considered as poor candidates. SR recovery allows a higher freedom from CHF and rehospitalization, with a better functional recovery when compared to AF
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
A learning-by-doing approach to entrepreneurship education: evidence from a short intensive online international program
Full text linkEntrepreneurship is considered a key driver for economic growth. Therefore, more and more studies are investigating the role and effectiveness of entrepreneurship education. In this context, the present study is aimed at investigating the effectiveness of entrepreneurship programs, with a learning-by-doing approach, on the entrepreneurial intention, entrepreneurial characteristics (entrepreneurial attitude, entrepreneurial self-efficacy, entrepreneurial mindset, core self-evaluation) and entrepreneurial skills (creativity, financial literacy, marshaling of resources, planning, teamwork). The study has analyzed a short intensive online entrepreneurship program, which adopts a learningby-doing approach and targets students from different European technical universities, with different levels of education and different entrepreneurial backgrounds, giving them the opportunity to work on different types of projects. Pre-and post-course surveys were conducted in order to perform qualitative analyses on the effectiveness of the program. The results show that the entrepreneurial intention and perception of the entrepreneurial characteristics and skills of the students increased after participation in the program. In addition, our findings reveal that the program appears to be more effective for MSc students than for PhD ones and for students who had never attended any entrepreneurship program before, while there is no difference in the effectiveness of the program in terms of gender
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