1,720,974 research outputs found
Valutazione teorica e sperimentale delle proprietà di isolamento acustico di pannelli in sughero
No full textLa normativa sui requisiti acustici passivi degli edifici impone soluzioni sempre più performanti, soprattutto se riferiti all'isolamento acustico di facciata; ci si trova di fronte al problema di ottenere elevate prestazioni acustiche con spessori contenuti della parete. Nel presente studio è stata effettuata una campagna di misure di potere fonoisolante di pannelli in sughero da impiegarsi in intercapedine. Le misure sono state effettuate presso il Laboratorio di Acustica del Dipartimento di Ingegneria Industriale - Università di Perugia. In una prima fase è stato analizzato il potere fonoisolante dei soli pannelli, di diverso spessore e densità, montati in singolo strato su un telaio in legno dalle dimensioni contenute (area totale 2,63 m2); nella seconda fase, sulla base dei risultati ottenuti, sono state eseguite misure di potere fonoisolante di pareti doppie in muratura con pannelli di sughero ad alta densità montati in intercapedine, in conformità con quanto stabilito dalle norme tecniche UNI EN ISO 140-3 e UNI EN 717-1. Le pareti sono state realizzate con elementi edilizi classici in laterizio (tramezze forate, tramezze semipiene) a formare diverse combinazioni e spessori totali. L'indagine ha riguardato tre differenti criteri di posa in opera: con intercapedine d'aria, senza intercapedine d'aria e con doppia intercapedine d'aria, montando i pannelli su appositi listelli in materiale elastico. I risultati hanno fornito valori del potere fonoisolante dell'ordine di 50 - 52 dB, poco influenzati dalle caratteristiche del materiale, i quali sono stati comparati con quelli ottenuti per via teorica mediante simulazione
Left atrial strain in left ventricular diastolic dysfunction: have we finally found the missing piece of the puzzle?
No full textThe noninvasive estimation of diastolic function with echocardiography as a surrogate of left ventricular filling pressure is considered an essential step in the clinical evaluation of patients with conditions predisposing to heart failure (HF). Latest algorithms for the assessment of diastolic dysfunction (DD) lay on several 2D standard parameters and describe a precise grading to quantify its severity. The persistence of a “gray zone” of values in which DD quantification is not possible, together with an epidemiological increase of conditions predisposing to heart failure with preserved ejection fraction (HFpEF), has led to the search and use of parameters with higher specificity and sensitivity: one of these is left atrial (LA) longitudinal strain in the frame of speckle tracking echocardiography (STE). LA anatomy and mechanics are crucial for preserving left ventricular (LV) function and asymptomatic condition of the patient. LA longitudinal strain is angle-independent, thus overcoming Doppler limitations, and provides reproducible measures of LA deformation. This review examines the latest evidences concerning the use of LA longitudinal strain in the assessment of diastolic function and HFpEF, with a particular focus on its role in standard echocardiographic algorithms or as a lone parameter to guide diagnosis and therapeutic management
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
Catheter inversion during cavotricuspid isthmus catheter ablation: the new shaft visualization catheter reduces fluoroscopy use
Full text linkAims: Catheter ablation (CA) is the choice therapy of cavotricuspid isthmus (CTI) atrial flutter. The aim of this study was to describe our approach to improve the CTI ablation using a zero-fluoroscopy (ZF). The procedural difficulties could be related to anatomical characteristics of the CTI. Methods: One hundred eighty-eight patients that performed CA of CTI were retrospectively and consecutively evaluated between 2017 and 2019. The studied population was divided into two groups. Eighty-eight patients who were undergone CA using ablation catheter without shaft visualization catheter (NSV) were Group 1. One hundred patients were undergone CA using ablation catheter with a shaft visualization (SV); they were Group 2. The catheter was looped at the Eustachian ridge after 200 seconds of radiofrequencies (RF) without elimination of local electrogram. Results: A conduction line block of CTI was obtained in all patients of Group 2 using a ZF approach. In 16 patients of Group 1, the catheter inversion was obtained using fluoroscopy to avoid damages during its loop. In Group 2, a complete CTI block was obtained with a catheter inversion approach in ten patients without fluoroscopy, visualizing the shaft and the tip of the ablation catheter on the electroanatomic (EAM) map. In the overall population studied the use of SV had a linear correlation with the ZF approach (r =.629; P <.001). The duration of RF was lower in Group 2 than in Group 1 (Group 1: 27.8 ± 6.3 vs Group 2: 15.6 ± 7.2 minutes; P <.01). The procedure time between two groups was lower in Group 2 than in Group 1 (Group 1: 58.4 ± 22.4 vs Group 2: 42.2 ± 15.7 minutes; P <.01). No differences between two groups were documented regarding success and complications. Conclusions: The visualization of the shaft's catheter on the EAM permitted the catheter inversion safely in order to overcome some complex CTI anatomy and obtain bidirectional block. The SV reduced procedure time, RF applications and fluoroscopy exposition during CTI ablation. © 2021 The Author
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
- …
