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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
Sostituzione valvolare aortica isolata per stenosi pura associata a disfunzione ventricolare sinistra: risultati del VERDI (ValvE Replacement with left ventricular Dysfunction Italian surgical Study)
No full textSmall prosthesis (size23-25) for mitral valve replacement. Analysis of postoperative outcome from a retrospective multicenter study.
No full textOBJECTIVES: To assess through a retrospective multicenter analysis the postoperative results of mitral valve replacement (MVR) with small prosthesis (size 23-25). The impact of small prosthetic size at mitral position on postoperative outcome after MVR is unknown.
METHODS: From January 1989 to December 2001, 285 patients (mean age 62±14 years, 23% male and 77% female) submitted to MVR with small artificial valves were identified from institutional databases. Surgery in emergency was required in 54 cases, re-operation in 61, and associated procedures in 68, respectively. Thirty-two patients had size-23 mitral prosthesis, whereas 253 patients had size-25 artificial valve. Mechanical valve was implanted in 243 patients, whereas 38 patients had a biological prosthesis. Preservation of the native valve (one or both leaflets) was accomplished in 114 patients. Postoperative survival, morbidity and functional capacity were assessed. Univariate and multivariate analysis were carried out to evaluate determinants of postoperative outcome.
RESULTS: Follow up was complete, and 1112 patient-years were available for the analysis. There were 12 early and 41 late deaths (34 cardiac-related). Kaplan-Meyer estimation showed 91% survival at 2 years and 82% at 5 years. Significant improvement of functional capacity was observed postoperatively in the majority of the patients. Cardiac-related complications occurred in 102 patients (36 major events). At multivariate analysis only the use of biological valve was identified as independent predictor of unfavorable postoperative result.
CONCLUSIONS: Mitral valve replacement with small prosthesis in adult patients has a favorable outcome. Further investigations are ongoing to elucidate whether patient/prosthesis mismatch at the mitral level affects the results of MVR
Isolated aortic valve stenosis with left ventricular dysfunction. Impact of prosthetic size on postoperative outcome from a retrospective multi-institutional study.
No full textVariations 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
Influence of patient-prosthesis mismatch on postoperative outcome after aortic valve replacement for pure aortic stenosis in the presence of impaired left ventricular contractility
No full textOBJECTIVES: To assess the effects of patient/prosthesis mismatch (PPM) (EOAI < 1 cm2/m2) on postoperative results of patients submitted to aortic valve replacement (AVR) for pure valve stenosis with concomitant left ventricular dysfunction (LVEF ≤ 40%). The persistence of left ventricular outflow tract obstruction after AVR might affect postoperative results in the presence of LV contractile impairment.
METHODS: From January 1989 to December 2001, 201 patients submitted to AVR for pure aortic valve stenosis and affected by LV dysfunction (mean LVEF 30±6.8%) were retrospectively identified. After surgery, 161 patients had no PPM whereas PPM was present in 40 patients (mean EOAI 0.87±0.07 cm2/m2). All patients were followed up in terms of postoperative survival, morbidity and functional capacity. Univariate and Cox regression analysis were carried out to evaluate predictors of postoperative outcome.
RESULTS: Follow up was 99,8% complete, and 985 patients/year were available for the analysis. No differences were found between the two groups in terms of demographics, except for age (73±9 years in PPM group, and 67±11 years in the second group, respectively). Adjusted Kaplan-Meyer estimations did not show any difference between the two groups in terms of postoperative event-free outcomes. Postoperative functional capacity improved in the majority of the patients, irrespective of the presence of PPM. At multivariate analysis PPM did not show to represent a negative determinant of postoperative outcome, whereas advanced age and NYHA class were predictive of unfavorable results.
CONCLUSIONS: After AVR for pure aortic stenosis in the presence of LV dysfunction, PPM did not apparently influence mortality and morbidity outcomes. Further investigations are necessary to elucidate LV response in this setting
Risultati a lungo termine di uno studio multicentrico della sostituzione valvolare mitralica con protesi di piccole dimensioni (23-25)
No full textStudio morfometrico dei graft venosi ed arteriosi per bypass Aortocoronarico in pazienti affetti da insufficienza renale cronica: risultati preliminari
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