1,720,987 research outputs found
Data Mining methods for the stratification of the arrhythmic risk in young and master athletes
No full textThe paper describes the data mining procedures concerning ECG signals and other cardiovascular blood parameters collected at the Ospedale Maggiore di Crema to evaluate the cardiovascular response to exercise in young and master athletes, compared with control groups of untrained subjects. After recruiting four groups of healthy athletes and sedentary subjects, with age under and over 40, we analyzed the collected ECG and cardiovascular data by means of clustering techniques and Artificial Neural Networks, obtaining cross-validated classifications and significant variable differences among clusters. We could establish some important relationships between physical activity, age, sex, and cardiovascular parameters. In particular the existence of significant differences in the cardiovascular status of these groups was shown, depending in particular on the MSE1, PNN20, VO and FC variables. This will make it possible to follow the subjects examining the variability of these parameters over time, in order to identify indicators of arrythmic risk that may help to prevent possibly fatal cardiac events
Cardiovascular Modifications and Stratification of the Arrhythmic Risk in Young and Master Athletes
No full textThis paper aims to evaluate the cardiovascular response to exercise in young and master athletes. The study involves comparison with control groups of untrained subjects of the same age. The paper describes in particular the processing methods and results concerning the ECG signals collected during exercise test. Methods include PNN calculation, Multiscale Entropy analysis (MSE), and a comparison between clustering and an Artificial Neural Network analysis performed by means of chaotic attractors. The analyses carried out lead to a good stratification of the subjects, especially in terms of the MSE1 variable. Future developments are underway supported by many other diagnostic tests administered to the same subjects
Non-invasive assessment of risk for severe tachyarrhythmias by means of non-linear analysis techniques
Full text linkSudden death remains a phenomenon of disturbing proportions, displaying a mean incidence of 300,000-350,000 persons/year in the USA (0.1-0.2% of the general population). In Europe, the figures are very similar. In 90% of cases, sudden death has an arrhythmic cause. Prevention of Sudden Cardiac Death (SCD) constitutes one of the most important challenges of modern cardiology. In order to make a real progress in this field it is crucial to precisely identify increased risk for serious ventricular tachyarrhythmias. In this study the effectiveness of different methods of the non-linear analysis (NLA) of ECG in the risk stratification of patients with ventricular arrhythmias is evaluated, and these non-invasive parameters are correlated with the results of invasive electrophysiological study (EPS). We evaluated 25 patients with history of cardiac arrest, syncope, sustained or nonsustained ventricular tachycardia (VT). The study group was compared with a control group of 25 healthy subjects. All patients underwent both electrophysiologic study (EPS) and non-linear analysis (NLA) of ECG. Patients were classified through the application of a clustering procedure to the whole set of functions, and a comparison between the results of non-linear analysis of ECG and EPS was performed. Results are presented and discussed
Non-linear data mining methods to assess the impact of physical training on the cardiovascular system of subjects from different age groups
No full textA set of non-linear data mining methods have been applied to ECG signals and other cardiovascular and blood parameters to evaluate the cardiovascular response to exercise in young and master athletes, compared with control groups of untrained subjects of the same age. Methods include PNN calculation, Multiscale Entropy analysis (MSE), and a comparison between clustering and an Artificial Neural Network analysis performed by means of chaotic attractors. After recruiting four groups of healthy athletes and sedentary subjects, with age under and over 40, we analyzed the collected data, obtaining cross-validated classifications and significant variable differences among clusters. The analyses lead to a good stratification of the subjects, establishing some important relationships between physical
activity, age, sex, and cardiovascular parameters. In particular the existence of significant differences in the cardiovascular status of hese groups was shown, depending in particular on the MSE1, PNN20, VO and FC variables. This will make it possible a follow-up of the subjects, analyzing the above specified parameters over time, in order to identify possible markers of increased arrhythmic risk, useful to prevent fatal cardiac events
Non-linear analysis of ECG signals as a method for the prognosis of letal tachyarrhythmias
No full text
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
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