1,721,431 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
Adjusted indirect meta-analysis of Aspirin plus Warfarin at international normalized ratios 2 to 3 versus Aspirin plus Clopidogrel after acute coronary syndromes
No full textAfter acute coronary syndromes,the beneficial effect of aspirin plus clopidogrel (A + C) or aspirin plus dose-adjusted warfarin (A + W) compared with aspirin alone is well established. However, these regimens were never compared. To compare the risk-benefit profile of A + C versus A + W after acute coronary syndromes, major medical databases for randomized controlled trials comparing 1 of these combined approaches versus aspirin alone after an acute coronary. syndrome (updated June 2006) were searched. Evaluated end points were major adverse events [MAEs: all-cause death, acute myocardial infarction [AMI], thromboembolic stroke, major bleeds, and overall risk of stroke [hemorrhagic or ischemic]). Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated for (1) A + W versus aspirin alone, (2) A + C versus aspirin alone, and (3) A + W versus A + C using adjusted indirect meta-analysis. Thirteen studies were included, totaling 69,741 patients. Ten compared A + W versus aspirin alone and 3 compared A + C versus aspirin alone. Each combined approach yielded a significantly lower risk of MAEs, albeit an increased risk of major bleeds, compared with aspirin alone. No significant difference was found for A + W versus A + C for risk of overall MAEs, death, or AMI. However, A + W versus A + C was associated with a significantly lower risk of thromboembolic stroke (OR 0.53, 95% CI 0.31 to 0.88, number needed to treat 60) and all types of stroke (OR 0.58, 95% CI 0.35 to 0.94, p = 0.038), but also with increased risk of major bleeds (OR 1.9, 95% CI 1.2 to 2.8, number needed to harm 300). In conclusion, after an acute coronary syndrome, A + W and A + C are comparable in the prevention of MAEs, death, and AMI compared with aspirin alone. Allocating 100 patients to A + W (at international normalized ratio 2 to 3) with respect to A + C could prevent 17 thromboembolic strokes while causing 3 major bleeds. (c) 2007 Elsevier Inc. All rights reserved
Increased brain natriuretic peptide secretion is a marker of disease progression in nonobstructive hypertrophic cardiomyopathy.
No full textBACKGROUND: Hypertrophic cardiomyopathy (HCM) is associated with increased plasma brain natriuretic peptide (BNP), but sequential plasma and myocardial BNP assessment in stable and dilated HCM has never been performed. METHODS AND RESULTS: Forty consecutive HCM patients (42 +/- 8 years, 25 males) underwent cardiac catheterization, angiography, and left ventricular (LV) endomyocardial biopsy. During follow-up (70.5 +/- 6.7 months), 30 patients (Group 1) remained stable whereas 10 patients (Group 2) progressed to dilated phase. Group 2 patients underwent a second invasive study with LV biopsy. BNP plasma levels were measured at baseline and at follow-up in all patients. All biopsies were processed for histology and immunohistochemistry with anti-BNP antibodies. BNP plasma levels remained unchanged in Group 1, whereas it significantly increased in all Group 2 patients who exhibited an elevation of LV and right ventricular end-diastolic pressure. Immunohistochemistry showed an increase of BNP-positive myocytes in follow-up biopsies when compared with baseline (75.0 +/- 15.0 % versus 29.8 +/- 10.0 %; P = .005) with a significant correlation with LV end-diastolic pressure (r = 0.78, P < .001) and plasma BNP (r = 0.83, P < .001). CONCLUSIONS: Progression to end-stage of HCM is characterized by further increase of myocardial and plasma BNP. Serial assessment of plasma BNP may provide noninvasive recognition of hemodynamic deterioration, allowing prompt institution of heart failure therapy
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
New insights into molecular mechanisms of diffuse coronary ectasiae: A possible role for VEGF
No full textBACKGROUND: Diffuse coronary artery ectasiae (DCE) are occasionally found at necropsy or at angiography. Pathogenetic mechanisms of DCE are still poorly known. Matrix metalloproteinases (MMPs), tissue inhibitors of MMPs (TIMPs) and vascular endothelial growth factor (VEGF) are involved in vascular remodeling and may play a role in DCE. METHODS: A total of 1280 consecutive coronary angiograms performed in a single institution in 1 year were screened. DCE were found in 15 patients. Diagnosis at hospital admission was acute coronary syndromes in all of them. Two patients died during initial admission and 1 refused blood sampling; the remaining 12 patients were enrolled in the study. No patient with DCE exhibited coronary stenoses. Plasma levels of VEGF, MMP-2, TIMP-1, TIMP-2 and C-reactive protein (CRP) were measured in these 12 patients 12 months after discharge during a silent clinical phase, in 12 age- and sex-matched patients with stable angina (SA) and coronary artery disease, and in 12 age- and sex-matched patients with normal coronary arteries (NCA). RESULTS: VEGF levels were higher in patients with DCE than in SA or NCA (151.6 pg/ml [36.2-252.9] vs. 66.6 pg/ml [36.4-93.3] and 54.8 pg/ml [14.5-87.1], respectively, p = 0.012]. TIMP-2 levels were lower in DCE and SA than in NCA (5.9 ng/ml [0-33.6] and 5.0 [0-17.4] vs. 139.3 ng/ml [114.4-237.4], respectively, p < 0.001). TIMP-1 and MMP-2 plasma levels were similar in all groups (p = NS), and CRP levels were within normal limits (< 3 mg/L) in most patients, irrespective of their coronary anatomy (75% for DCE, 66% for SA, and 84% for NCA [p = NS]). CONCLUSIONS: Symptomatic patients with DCE typically present with an acute coronary syndrome and exhibit lack of obstructive stenosis at angiography, decreased plasma levels of TIMP-2 and raised plasma levels of VEGF. The simultaneous occurrence of reduced MMPs inhibition and increased angiogenetic activity suggests an accelerated and persistent extracellular matrix remodeling process favouring arterial remodeling and aneurysms formation which is likely to enhance the risk of thrombosis because of low shear stress
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
- …
