1,720,968 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
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
Antiarrhythmic efficacy of Penticainide and comparison with Disopyramide, Flecainide, Propafenone and Mexiletine by acute oral drug testing.
No full textThe antiarrhythmic efficacy of a new class I agent, penticainide, was evaluated by acute oral drug testing and compared in the same patient population with the efficacy of disopyramide, flecainide, mexiletine and propafenone. Twenty-five patients with high-grade chronic ventricular arrhythmias entered the study. During acute oral drug testing, penticainide (7 mg/kg) was effective (more than 90% reduction in ventricular premature complexes and complete abolition of class 4A and 4B arrhythmias) in 17 of 25 subjects (68%). The mean plasma level of the drug at 90 minutes was 4.4 +/- 1.9 micrograms/ml; at the same time increases in the PQ interval (from 168 +/- 27 to 189 +/- 31 ms, p less than 0.0001) and QRS duration (from 89 +/- 14 to 96 +/- 18 ms, p less than 0.001) were observed. The QTc was slightly but not significantly shortened in the overall population; however, in the subgroup with a basally prolonged QTc (n = 8), a significant reduction was observed (from 456 +/- 8 to 440 +/- 18 ms, p less than 0.02). No adverse effects were reported. The antiarrhythmic efficacy of the other drugs tested in the same population was: disopyramide, 12 of 19 (63%); flecainide, 13 of 24 (54%); propafenone, 13 of 24 (54%); and mexiletine, 7 of 20 (35%). Penticainide appears to be a well-tolerated and effective compound of potential value for treatment of ventricular arrhythmias
Late enhancement of a left ventricular cardiac fibroma assessed with gadolinium-enhanced cardiovascular magnetic resonance
No full textMultiple comparison of several antiarrhythmic agents by acute oral drug testing in patients with chronic ventricular arrhythmias
No full textThis study addresses the question of the choice of treatment for the individual patient with chronic ventricular arrhythmias. Acute oral drug testing offers a pragmatic approach to the rapid selection of the drug with the best efficacy/side-effect ratio by allowing multiple comparisons within the same patient. Forty patients with chronic ventricular arrhythmias received a single oral dose of the following antiarrhythmic drugs: flecainide 200 mg, propafenone 450 mg, disopyramide 300 mg, mexiletine 400 mg, tocainide 800 mg, verapamil 160 mg, propranolol 120 mg. Criteria for efficacy were suppression of complex ventricular arrhythmias and a greater than 90% reduction in premature ventricular beats lasting for at least 2 h. An antiarrhythmic effect was achieved with each of the drugs in the following percentages of patients: flecainide 69.4%, propafenone 67.5%, disopyramide 54.8%, mexiletine 45.2%, tocainide 31.3%, verapamil 31.3%, propranolol 12.5%. In no case was worsening of arrhythmia observed. At the end of the acute testing phase, the drug that had proved most effective in each patient was administered at a full dosage for 72 h. A concordant response between the two phases was observed in 80% of patients and was as high as 89% when the analysis was limited to flecainide and propafenone. This study shows the feasibility and practical advantages for patient management of a multiple comparison of antiarrhythmic drugs by acute oral drug testing. It also provides, in a non-invasive cost-effective manner, unique insights into the complex relationship between drug characteristics, individual responses and clinical efficacy
Efficacy e safety of Flecainide in Low-Risk patients with chronic ventricular arrhythmias. A two-year follow up.
No full textThe long-term efficacy and safety of flecainide (100 to 200 mg twice a day) were evaluated in 21 patients with high-grade, chronic ventricular arrhythmias who responded to and tolerated flecainide at a preliminary evaluation (200 mg, single oral dose). Antiarrhythmic response was evaluated at 3 days and 3, 6, 12, 18, and 24 months. The mean follow-up was 25 +/- 14 months (range 3 to 52). Four patients (19%) were excluded from efficacy analysis because of spontaneous decrease in baseline arrhythmia observed after 12 months of therapy. Effective arrhythmia suppression at both Holter monitoring and during exercise stress testing was maintained in 14 of 17 patients (82%). Mean frequency of premature ventricular contractions remained reduced by more than 95% throughout the follow-up. Five patients discontinued therapy between 3 and 18 months because of drug ineffectiveness (three patients, 18%) or side effects (two patients, 12%). In 12 patients (71%) long-term efficacy and tolerance were demonstrated. In no case was aggravation of arrhythmia or adverse cardiac effects observed. Side effects (5% to 29% of patients during follow-up) were usually minor and easily abolished by dosage reduction. In patients with chronic ventricular arrhythmias, flecainide maintained a favorable ratio between efficacy and side effects during a 2-year follow-up
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