1,720,982 research outputs found
A novel sensor to continuously monitor cardiac apex rotation
No full textThe left ventricular (LV) rotation is a key component of cardiac mechanics as recently shown by advanced imaging techniques. In healthy subjects, the cardiac rotation follows a specific pattern within the cardiac cycle in order to be effective: during isovolumic contraction all short-axis levels, from base to apex, rotate counterclockwise, when viewed from the apex, during ejection, the apex continues counterclockwise while the base reverses direction; thus cardiac apex rotation angle (CAR) reaches the maximum at End of Systole (ES). In diastole, the shearing forces built up during systole by cardiac rotation result in rapid untwisting which is thought to contribute to diastolic suction. Alterations in the normal pattern or magnitude of the cardiac rotation have been associated with cardiovascular diseases, such as chronic heart failure, tachycardia-induced dilated cardiomyopathy, dilated cardiomyopathy, hypertrophic cardiomiopathy, myocardial infarction and aortic stenosis. The analysis of CAR signal with respect to systolic and diastolic phases could be useful for the monitoring of cardiac function in patients with various degrees of heart failure as there are often delay and/or dyssynchrony phenomena which considerably reduce the overall mechanical efficiency of the heart. If an altered rotational dynamics determines a delay of maximum CAR into the Isovolumic Relaxation Period (IRP), the effective contribution of left ventricular twisting to systole must be considered the CAR value at the time of ES (CARES).
Continuous monitoring of LV rotation has not been attempted so far but may provide important information for long term management of heart failure patients.
We propose the use of an implantable gyroscopic sensor for the continuous monitoring of CAR. We evaluated in animals the CAR signal with respect to the systolic timing (CARES) and we tested its ability to reflect changes of LV function during acute ischemia
Safe cardiac mapping and catheter ablation using a novel remote catheter manipulator
No full textThe use of robotically-guided electrophysiology (EP) catheters has been recently proposed. To date, NIOBETM magnetic navigation system (Stereotaxis Inc., St. Loius, MO, USA) and SenseiTM robotic navigation system (Hansen Medical, CA, USA) are commercially available systems to enable remote control of electrophysiology (EP) catheters. However, the issue of providing a safe and effective way to perform remotely what commonly electrophysiologists carry out manually during EP procedures remains unsolved: one of the main concerns with the Sensei system is the risk of cardiac tamponade, as almost the full length of the catheter is encased in a rigid steerable sheath; ablation lesions produced with NIOBE system resulted less effective than those applied conventionally, as the maximal endocardial force exerted by the magnetically-guided catheter is generally lower than that applied by conventionally controlled catheters. The aim of this feasibility study on sheep was to demonstrate safety and efficacy of a novel Remote Catheter Manipulator (RCM) (Tre Esse Progettazione Biomedica srl, Bologna, Italy) which allows remote manipulation of standard steerable EP catheters, with no need of dedicated catheters or sheaths. The RCM preserves the safe buckling property of a standard EP catheter, entering the vasculature through commercially-available sheath-introducer. It is also equipped with a force feedback sensor-based mechanism to control the resistance encountered by the catheter while advancing, alerting the operator when a threshold force is exceeded
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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