1,721,298 research outputs found
A Workstation-Based System for 2-D Echocardiography Visualization and Image Processing
No full textParameters of cardiac function can be drawn from the analysis of echocardiographic image sequences, especially the motion of the ventricular wall, heart wall thickness, and shape parameters. Automatic image analysis and visualization allows reduced manual operations and, above all, ensures objectivity and repetition of analysis, which is essential when one wishes to calculate parameters based on variations, i.e., on image sequence analysis. In this paper, a system and the related software package for interactive echocardiographic image analysis and visualization are illustrated and discussed. Furthermore, the full model for smoothing, edge enhancement, and contour detection is discussed and a new technique based on the heat anisotropic diffusion model is presented. The results of automatic detection of the left ventricle contours are presented and discussed. © 1990 IEE
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
Optical flow computation in 2-D echocardiography
No full textA method based on the computation of the optical flow, or instantaneous velocity field, on sequences of two-dimensional (2-D) echocardiograms to quantify ventricular wall motion is presented. The method utilizes couples of consecutive frames to compute, for each pixel, the 2-D apparent velocity vector which characterizes the interframe motion. By scaling the velocity amplitudes with gray-level values, velocity images can be generated from each couple of frames in the sequence. Horizontal and vertical velocity component images are generated frame by frame during the cardiac cycle. Referring the velocity vectors to a intraventricular central point, radial and tangential velocity component images are also generated
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
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