1,721,056 research outputs found
Ventricular Late Potentional Analysis by Adaptive Filtering and Cross-Spectral Technique
No full textThis paper presents a novel technique devoted to the detection of late potentials in frequency domain which consists in an adaptive filtering of the ST segment and in a cross-spectral analysis of the filter output. The approach is based on the evidence that late potentials are related to frequency components higher than those present in the high-resolution electrocardiogram of healthy subjects. We also outline the correlation between late potentials and the abrupt modification of the spectro-temporal representation of the ST segment by adopting a cross-spectral technique. We propose an index to measure the presence of anomalous frequency components which was proved effective by means of the analysis of synthetic signals as well as of real recordings. Particularly, we show the effectiveness of the proposed index in the clinical assessment of the arrhythmogenic right ventricular diseas
Detection of Ventricular Late Potentials by Adaptive Filtering and Cross-Spectral Analysis
No full textThis paper presents a novel technique to detect ventricular late potentials in frequency domain. The approach is based on the assumption that ventricular late potentials are associated with the occurrence of signal components at higher frequencies than those present in the high-resolution ECG of healthy subjects. This justifies the adoption of an adaptive high pass filter whose cut-off frequencies in set according to the characteristics of the averaged high-resolution ECG. Subsequent segments selected on the filter output are cross-spectral analyzed to outline the correlation between ventricular late potentials and the abrupt modification of the spectro-temporal representation of the terminal portion of the QRS complex and the early ST segment. An index is defined to detect anomalous frequency components. This is shown effective by processing real recording as well as signals in which simulated waveforms were superimposed on the ECG. The index is applied to the analysis of the high-resolution ECG of patients with Arrhythmogenic Right Ventricular Disease. The results suggest that the proposed technique may be utilized in the stratification of the seriousness of Arrhythmogenic Right Ventricular Diseas
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
Analyzing late Ventricular Potential using an improved alignment technique for signal averaging to increase detection reliability
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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