1,720,989 research outputs found
Exercise Hemodynamics in Chronic Heart Failure: Physiological and Clinical Aspects
No full textChronic heart failure is intrinsically associated with exercise intolerance. Understanding the pathophysiological background of exercise intolerance is essential for optimizing the response to current and future therapies aiming at an improvement of exercise capacity. Each step in the oxygen transport chain and the rate of oxygen utilization can be responsible for the reduced exercise capacity in CHF patients. In this thesis, additional physiological insight is provided by characterizing central and peripheral determinants of oxygen uptake during (sub)maximal exercise and recovery. In addition, the clinical effects and its underlying mechanisms of high-intensity interval training (HIT) with or without cardiac resynchronization therapy (CRT) were explored. In conclusion, in part I (physiological aspects) we demonstrated physiological heterogeneity during maximal exercise, submaximal exercise and recovery after maximal exercise. Additional insight in the pathophysiology of exercise intolerance in CHF is essential for developing novel therapies. Moreover, characterization of the nature of exercise limitations is needed to ascertain which determinant should be primarily targeted for therapy. We investigated several new exercise related parameters (Q patterns, ratio of Q-to-VO2, SmO2 amplitude and OP relative recovery) that can be used to identify the main limitation. Further research is necessary to explore the clinical usefulness and prognostic significance of these novel approaches. In part II (clinical aspects), we evaluated HIT induced effects on exercise capacity and its physiological determinants in CHF patients with or without CRT. Although we observed benefits at a group level of several maximal and submaximal exercise parameters, there was still a considerable variation between individual patients. In future studies, the clinical and physiological profile of a responder to both CRT and exercise training should be clarified to enable a more tailored therapeutic approach. A prediction model with exercise related parameters such as proposed in this thesis could optimize benefits for individual patients and may lead to lower healthcare costs
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Oxygen uptake kinetics in chronic heart failure : clinical and physiological aspects
Get PDFChronic heart failure (CHF) is a clinical syndrome characterized by exercise intolerance. Because resting indices of cardiac function and the level of perceived exercise intolerance correlate poorly with the exercise performance of these patients, exercise testing has become an important tool for the evaluation and monitoring of heart failure. Whereas the maximal aerobic capacity (peak VO2) has been shown to be a reliable indicator of the severity and prognosis of heart failure, submaximal exercise parameters may better reflect the ability to perform daily physical activities. Oxygen (O2) uptake kinetics describe the rate of change in oxygen uptake (VO2) during onset or recovery of exercise (O2 onset and recovery kinetics, respectively). Previous studies showed that, compared to healthy individuals, CHF patients have slower O2 onset and recovery kinetics, with the degree of the delay correlating with the functional impairment in these patients. However, it is not well established whether O2 uptake kinetics are sensitive to the effects of therapeutic interventions in CHF patients. Moreover, knowledge is lacking on the pathophysiological background of the delay in O2 uptake kinetics in CHF patients. This thesis addressed the following central questions: 1. Are O2 uptake kinetics useful in clinical practice to quantify and predict the effects of physical training in CHF patients? 2. What are the physiological determinants of O2 uptake kinetics in CHF patients
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Exercise electrocardiography in athletes: diagnostic accuracy and pathophysiological background
No full textThis thesis gives insight in the value of exercise testing used during pre-participation screening in asymptomatic athletes. Exercise testing is commonly used to detect coronary heart disease. This thesis shows that exercise testing combined with analysis of inspiratory and expiratory breath gasses increased the accuracy of exercise testing to detect any form of dysfunction of the heart. The athletes with abnormal test results were referred to the department of Cardiology for further diagnostic evaluation. The majority of these athletes didn’t show any signs of coronary heart disease. In order to explain the abnormal exercise test results, the geometry of the heart of the athletes was evaluated. Athletes with abnormal exercise test results did not shown the typical signs of the so-called athlete’s heart. However, the function of the smallest arteries (microcirculation) of athletes was attenuated. Therefore, it can be hypothesized that at least a part of the athletes with abnormal exercise test results without obstructive coronary heart disease show signs of premature coronary heart disease together with an attenuated microvascular function. These athletes could be at risk for the development of exercise-induced myocardial ischemia and subsequently for the development of a myocardial infarction and/or sudden cardiac death. Therefore, the findings of this thesis may have important clinical implications for athletes with abnormal test results without obstructive coronary heart disease, as a new potential substrate for the occurrence of sudden cardiac death in athletes is identified
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