1,721,015 research outputs found
Contemporary differences between bicuspid and tricuspid aortic valve in chronic aortic regurgitation
No full textObjectiveTo comprehensively explore contemporary differences between bicuspid aortic valve (BAV) and tricuspid aortic valve (TAV) patients with chronic haemodynamically significant aortic regurgitation (AR).MethodsConsecutive patients with chronic >= moderate-severe AR from a tertiary referral centre (2006-2017) were included. All-cause mortality, surgical indications and aortic valve surgery (AVS) were analysed.ResultsOf 798 patients (296 BAV-AR, age 46 +/- 14 years; 502 TAV-AR, age 67 +/- 14 years, p<0.0001) followed for 5.5 (IQR: 2.9-9.2) years, 403 underwent AVS (repair in 96) and 154 died during follow-up. The 8-year AVS incidence was 60%+/- 3% versus 53%+/- 3% for BAV-AR and TAV-AR, respectively (p=0.014). The unadjusted (real-life) 8-year total survival was 93%+/- 7% versus 71%+/- 2% for BAV-AR and TAV-AR, respectively (p<0.0001), and became statistically insignificant after sole adjustment for age (p=0.14). The within-group relative risk of death in BAV-AR patients demonstrated a large age-dependent increase (two fold at 50-55 years, up to 10-fold at 70 years). The presence of baseline symptoms was significantly associated with death for both BAV-AR (p=0.039) and TAV-AR (p<0.0001), but the strength of the association decreased with age adjustment for BAV-AR (age-adjusted HR 2.43 (0.92-6.39), p=0.07) and not for TAV-AR (age-adjusted HR, 2.3 (1.6-3.3), p<0.0001). As compared with general population, TAV-AR exhibited baseline excess risk which further increased at left ventricular ejection fraction (LVEF) <60% and left ventricular end-systolic dimension index (LVESDi) >20 mm/m(2); similar thresholds were observed for BAV-AR patients.ConclusionBAV-AR patients were two decades younger than TAV-AR and underwent AVS more frequently, resulting in a considerable real-life survival advantage for BAV-AR that was determined primarily by age and not valve anatomy. Pragmatically, regardless of valve anatomy, patients with haemodynamically significant AR and age >50-55 years require a low-threshold for surgical referral to prevent symptom development where LVEF 20 mm/m(2) seem appropriate referral thresholds
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
IMPACT OF LEFT VENTRICULAR DIASTOLIC DYSFUNCTION IN PATIENTS WITH SYMPTOMATIC MITRAL STENOSIS
No full textVariations 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
Potential Impact of Concomitant Valvular Lesions and Coronary Artery Bypass Surgery on Outcome in Low-Gradient Severe Aortic Stenosis With Preserved Ejection Fraction
No full textDispelling 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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