1,720,956 research outputs found
Seven-year performance of the Edwards Prima Plus stentless valve with the intact non-coronary sinus technique
No full textOBJECTIVES: Late results after stentless aortic valve replacement (AVR) may be jeopardized by progressive aortic dilatation. To define functional outcome using the intact non-coronary sinus technique, all patients operated using the stentless Edwards Prima Plus xenograft were assessed. METHODS: Between January 2000 and August 2007, 154 patients, aged 71 +/- 9 years, underwent stentless AVR using a technique, which replaces the non-coronary sinus and stabilizes two of three commissures. Indication was aortic valve stenosis (AS) in 103 (67%) patients: 33 (21%) had bicuspid valve and four endocarditis. Ninety-six (62%) patients were in NYHA III-IV, and 13 (8%) had LVEF <30%. Associated procedures were required in 59 (38%) patients (CABG, 34; ascending aorta, 22; others 3). Study endpoints were survival, freedom from valve-related events, clinical status, and graft function. RESULTS: There were two hospital and two late deaths during a 48 +/- 19 months (1-92) follow-up (97 +/- 3% survival at seven years). Seven-year freedom from structural failure, nonstructural failure, and endocarditis was 99 +/- 1%, 97 +/- 3%, and 98 +/- 2%. Follow-up NYHA (96 vs ten patients in class III-IV, p = 0.001), and cardiac function (13 vs one patient with LVEF <30%, p = 0.02) were improved. Xenograft performance was satisfactory: 0-2 + aortic insufficiency (AI) in 147 (98%) patients, mean trans-prosthetic pressure gradient 8 +/- 4 (0-25 mmHg). Aortic root diameters were comparable to postoperative values (sinus of Valsalva, 36 +/- 8 vs 35 +/- 9 mm, p = ns; sinotubular junction, 32 +/- 7 vs 34 +/- 8 mm, p = ns). CONCLUSIONS: Stentless AVR with non-coronary sinus replacement affords excellent late outcome and low rate of valve-related events, even in complex patients (bicuspid valve, LV failure, and endocarditis). Aortic root dimensions remain stable over time allowing rewarding xenograft function
The Pathology of TRI-Tech Valve Leaflet Escape
No full textBACKGROUND AND AIM OF THE STUDY:
The study aim was to investigate leaflet escape in the TRI-Tech mechanical valve, as reported in three patients.
METHODS:
Among the three patients, one patient with a mitral prosthesis from which leaflet escape occurred underwent a successful reoperation. However, two patients with an aortic prosthesis from which leaflet escape occurred died suddenly. In addition, 150 unimplanted TRI-Tech valve prostheses were evaluated.
RESULTS:
Tab fracture was observed in all of the escaped leaflets, with a height asymmetry of 0.33 mm in the mitral valve, and 0.55 and 0.41 mm, respectively, in the two aortic valves. Height tab asymmetry was present in all unimplanted valves: this was 0.20 mm in 10% (in one valve the asymmetry was >0.35 mm). Height asymmetry was greatest in valves sized 21 to 25 mm. A review of data provided by the TRI-Tech quality control unit failed to demonstrate any reference to checking for tab symmetry.
CONCLUSION:
Significant tab malalignment was observed in the TRI-Tech valves in which tab fracture and leaflet escape had occurred. Tab asymmetry was also present in all unimplanted valves; this was >0.20 mm in 10% of units, and in one case was as high as in valves that had undergone leaflet escape. As tolerance for tab asymmetry is unknown and the risk of rupture is unpredictable, an interruption of the implant program with prophylactic replacement of the implanted TRI-Tech valves must be considered judicious
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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