1,720,978 research outputs found
Left atrial strain after maximal exercise in competitive waterpolo players
No full textLeft atrial (LA) function is a determinant of left ventricular (LV) filling. It carries out three main functions: reservoir, conduit, contractile. Aim of this study was to evaluate the role of LA and its deformation properties on LV filling at rest (R) and immediately after a maximal exercise (ME) through the speckle tracking echocardiography. Population enrolled was composed by 23 water polo athletes who performed a ME of six repeats of 100 m freestyle swim sets. At ME peak atrial longitudinal strain was reduced but all strain rate (SR) parameters increased, respectively positive peak SR at reservoir phase, SR negative peak at rapid ventricular filling (SRep) and SR negative peak at late ventricular filling (SRlp), that corresponds to atrial contraction phase. We showed a parallel increase in E and A pulsed Doppler wave and SRep and SRlp; particularly at ME, A wave and SRlp increased more respectively than E wave and SRep. SRlp was related to ejection fraction (EF) (r = −0.47; p < 0.01). At multivariate analysis SRlp was an independent predictor of EF (β: −0.47; p = 0.016). The increased sympathetic tone results into increased late diastolic LV filling with augmented atrial contractility and a decrease in diastolic filling time. During exercise LV filling was probably optimized by an enhanced and rapid LA conduit phase and by a vigorous atrial contraction during late LV filling
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
Left Ventricular Lead Placement for Biventricular Pacing in a Left Lateral Vein in a Patient with Congenital Atresia of the Coronary Sinus Ostium
Full text link: Coronary sinus ostial atresia (CSOA) is a rare kind of congenital heart anomaly. This creates a new drainage pathway for the cardiac venous flow, with the most common being a persistent left superior vena cava (PLSVC). During the implantation of a cardiac resynchronization therapy defibrillator, we discovered a case of CSOA in a patient who underwent aortic valve and ascending aorta replacement. CSOA led to the research and subsequent identification of a PLSVC, which drained in the CS. The left ventricular pacing lead was appropriately placed in a left lateral vein. This case report highlights the technical aspects and procedural difficulties that characterize this specific anatomical variant
Endurance and Strength Athlete's Heart: Analysis of Myocardial Deformation by Speckle Tracking Echocardiography
Full text linkBACKGROUND: Intensive training induces two morphological myocardial typologies of athlete's heart. Endurance training (ET) induces eccentric remodeling, bradycardia and better diastolic filling. Strength training (ST) determines concentric chamber remodelling maintaining a normal heart rate (HR). Aim of the study was to compare ET and ST athletes' heart using speckle tracking echocardiography (STE).
METHODS: 33 professional ET, 36 ST athletes, and 17 healthy controls (CT) were enrolled. All subjects underwent standard transthoracic echocardiography at rest and STE.
RESULTS: In ET group, HR was lower than ST group and CT group (p < 0.001; p < 0.01). ET group had higher E/A ratio than ST group and CT group (p < 0.01; p < 0.001). The left ventricular apical circumferential strain in ET group was lower than ST group and CT group (-21.6 ± 4.1% vs. -26.8 ± 7.7%, p < 0.05; vs. -27.8 ± 5.6%, p < 0.01). ET group had lower left ventricular twist (LVT) and untwisting (UTW) than ST group (6.2 ± 0.1° vs. 12.0 ± 0.1°, p < 0.01; -67.3 ± 22.9°/s vs. -122.5 ± 52.8°/s, p < 0.01) and CT group (10.0 ± 0.1°, p < 0.01; -103.3 ± 29.3°/s, p < 0.01). The univariate analysis showed significant correlation between E/A ratio and HR (r = -0.54; p < 0.001), LVT (r = -0.45; p < 0.01), UTW (r = 0.24; p < 0.05). At the multivariate analysis only HR was confirmed as independent predictor of diastolic function in all groups (Beta -0.52; p < 0.001).
CONCLUSION: In ET there was a better global systolic and diastolic functional reserve at rest observed with strain analysis and it maybe depended on autonomic modulation
Age related diastolic function in amateur athletes
No full textDiastolic function get worse with increasing age. Aim of this study was to investigate the impact of aerobic training on diastolic function with increasing age with speckle tracking echocardiography. We enrolled 125 amateur swimmers (AG), divided in three groups at increasing age: young athletes, adult athletes (AG2), old athletes (AG3). We enrolled 95 sedentary controls (SG) age-matched with athletes and divided into three groups: young sedentary group, adult sedentary group (SG2) and old sedentary group (SG3). AG had better diastolic function than SG. AG showed lower left ventricular twist than controls. E/A ratio got worse at increasing of age in all population (r = −0.34; p < 0.001); particularly in SG2 and SG3 there was a worsening of diastolic function respect to diastolic function of AG2 and AG3; in fact E/A ratio decreased with aging. Furthermore in SG E/A ratio showed a linear correlation with age (r = −0.54; p < 0.001); in AG this correlation was lost. Therefore the training and age were independent predictor of E/A (respectively β = −0.27; p = 0.004; β = −0.24, p = 0.008). Regular and aerobic training may minimize aging changes of diastolic function. This training-effect may play a key role to preserve diastolic filling in older athletes
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
- …
