1,721,020 research outputs found
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
Prognostic value of high-dose dipyridamole stress myocardial contrast perfusion echocardiography
Full text linkThe addition of myocardial perfusion (MP) imaging during dipyridamole real-time contrast echocardiography improves the sensitivity to detect coronary artery disease, but its prognostic value to predict hard cardiac events in large numbers of patients with known or suspected coronary artery disease remains unknown
Effect of Pharmacologic Stress Test Results on Outcomes in Obese versus Nonobese Subjects Referred for Stress Perfusion Echocardiography
No full textBackground Real-time contrast stress echocardiography (RTCSE) permits the simultaneous analysis of myocardial perfusion and wall motion during stress echocardiography, which has resulted in improved coronary artery disease detection. Although several studies have confirmed a protective effect of obesity in coronary artery disease, it is unclear whether this benefit is dependent on the functional significance of the disease. The objective of this study was to compare outcomes in obese versus nonobese subjects referred for pharmacologic RTCSE. Methods A retrospective comparison of wall motion and myocardial perfusion with RTCSE was assessed in 481 obese and 961 nonobese patients matched for age and gender without known coronary artery disease referred for either dobutamine (n = 1,056) or dipyridamole (n = 386) stress echocardiography at two separate institutions. Outcomes (death or nonfatal infarction) were determined over a median follow-up period of 1,195 days. Results Abnormal myocardial perfusion and/or wall motion was seen in 207 (20%) dobutamine and 61 (16%) dipyridamole studies. Abnormal rates were similar in obese (17%) and nonobese (19%) subjects. Event-free survival was significantly worse only for nonobese subjects referred for dobutamine RTCSE, with obesity (not test result) being an independent predictor of event-free survival on multivariate analysis (P = .001). No protective effect of obesity was observed following dipyridamole RTCSE. Conclusions Obese subjects in the United States referred for demand stress testing have better outcomes when directly compared with age- and gender-matched nonobese subjects with similar degrees of inducible ischemia
Association between Resting Global Longitudinal Strain and Clinical Outcome of Patients Undergoing Stress Echocardiography
No full textBackground: Reduced global longitudinal strain (GLS) of the left ventricle is associated with adverse prognosis in healthy subjects and in different cardiovascular conditions. Resting GLS may enable risk assessment independently from stress echocardiography (SE). We assessed whether there is an association of GLS measured at rest before SE with long-term outcome, independent of clinical parameters or reversible wall motion abnormalities and Doppler coronary flow velocity reserve. Methods: Five hundred thirty patients who underwent SE for ischemia evaluation between 2010 and 2012 and who had rest images available were selected. Resting GLS was measured off-line (absolute value <15% was considered abnormal). Cox models were used to examine the association between clinical variables, ejection fraction, SE variables, and resting GLS with mortality and cardiac events (cardiac death and nonfatal myocardial infarction). The independent prognostic value of GLS over known rest and stress variables was assessed. Results: Over a median follow-up of 7.5 years, 137 patients died from any cause and 50 had a nonfatal myocardial infarction. Patients with resting GLS <15% had significantly lower event-free survival (log-rank P < .0001). Resting GLS was significantly associated with risk of all-cause death and hard cardiac events, after adjustment for clinical risk factors, reversible wall motion abnormalities, and coronary flow velocity reserve. Adding resting GLS into a model with clinical, rest, and stress imaging variables significantly increased the model C index (P = .031). Conclusions: In a large cohort of patients with suspected coronary artery disease referred for SE, resting GLS <15% was independently associated with mortality and hard cardiac events, incremental to SE data. Model discrimination including resting GLS measurement was comparable to discrimination including SE results
Effect of Stress Perfusion and Wall Motion Response on Outcome of Obese versus Non-Obese Subjects Without Known Coronary Artery Disease
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
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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