1,720,971 research outputs found
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
Postsurgical aortic false aneurysm: Pathogenesis, clinical presentation and surgical strategy
No full textPostsurgical aortic false aneurysm occurs in less than 0.5% of all cardiac surgical cases and its management is a challenge in terms of preoperative evaluation and surgical approach. Although infections are well recognized as risk factors, technical aspects of a previous operation may have a role in pseudoaneurysm formation. The risk factors and clinical presentation of pseudoaneurysms and the surgical strategy are revisited in this article. © 2013 Italian Federation of Cardiology
Molecular rationale for the impairment of the MexAB-OprM efflux pump by a single mutation in MexA
Full text linkEfflux pumps of the Resistance-Nodulation-cell Division (RND) superfamily contribute to intrinsic and acquired resistance in Gram-negative pathogens by expelling chemically unrelated antibiotics with high efficiency. They are tripartite systems constituted by an inner-membrane-anchored transporter, an outer membrane factor protein, and a membrane fusion protein. Multimerization of the membrane fusion protein is an essential prerequisite for full functionality of these efflux pumps. In this work, we employed complementary computational techniques to investigate the stability of a dimeric unit of MexA (the membrane fusion protein of the MexAB-OprM RND efflux pump of Pseudomonas aeruginosa), and to provide a molecular rationale for the effect of the G72S substitution, which affects MexAB-OprM functionality by impairing the assembly of MexA. Our findings indicate that: i) dimers of this protein are stable in multiple μs-long molecular dynamics simulations; ii) the mutation drastically alters the conformational equilibrium of MexA, favouring a collapsed conformation that is unlikely to form dimers or higher order assemblies. Unveiling the mechanistic aspects underlying large conformational distortions induced by minor sequence changes is informative to efforts at interfering with the activity of this elusive bacterial weapon. In this respect, our work further confirms how molecular simulations can give important contribution and useful insights to characterize the mechanism of highly complex biological systems
Bicuspidy does not affect reoperation risk following aortic valve reimplantation
No full textAortic valve reimplantation has been shown to be a safe procedure. However, evidences of durability in bicuspid aortic valves (BAVs) are limited in the literature. Between 2002 and 2011, 132 patients (mean age 61 ± 12 years) underwent aortic valve reimplantation. In 24 patients (18%), aortic valve was bicuspid. Mean follow-up was 50 ± 26 months (range 1-102 months) and was 99% complete. In-hospital mortality was 0.8% (1 patient). Survival at 1 and 5 years was 99 and 94%, respectively. Overall freedom from aortic valve reoperation at 1 and 5 years was 96 and 90%, respectively, without significant difference between patients with bicuspid and tricuspid aortic valve. Freedom from aortic valve regurgitation >2+/4+, excluding patients reoperated, was at 1 and 5 years of 100 and 99%, respectively. Patients with valve cusp repair showed a higher rate of aortic valve reoperation; however, only postoperative aortic regurgitation >2+/4+ was significant risk factor for redo procedure at multivariate analysis. Aortic valve reimplantation in BAV without cusp repair provides excellent mid-term results. Further observations and longer follow-up are necessary to determine if BAV sparing, even in the presence of cusps alterations, could allow satisfying durability. © 2012 The Author
Coupling enhanced sampling of the apo-receptor with template-based ligand conformers selection: performance in pose prediction in the D3R Grand Challenge 4
No full textWe report the performance of our newly introduced Ensemble Docking with Enhanced sampling of pocket Shape (EDES) protocol coupled to a template-based algorithm to generate near-native ligand conformations in the 2019 iteration of the Grand Challenge (GC4) organized by the D3R consortium. Using either AutoDock4.2 or HADDOCK2.2 docking programs (each software in two variants of the protocol) our method generated native-like poses among the top 5 submitted for evaluation for most of the 20 targets with similar performances. The protein selected for GC4 was the human beta-site amyloid precursor protein cleaving enzyme 1 (BACE-1), a transmembrane aspartic-acid protease. We identified at least one pose whose heavy-atoms RMSD was less than 2.5 Å from the native conformation for 16 (80%) and 17 (85%) of the 20 targets using AutoDock and HADDOCK, respectively. Dissecting the possible sources of errors revealed that: (i) our EDES protocol (with minor modifications) was able to sample sub-ångstrom conformations for all 20 protein targets, reproducing the correct conformation of the binding site within ~ 1 Å RMSD; (ii) as already shown by some of us in GC3, even in the presence of near-native protein structures, a proper selection of ligand conformers is crucial for the success of ensemble-docking calculations. Importantly, our approach performed best among the protocols exploiting only structural information of the apo protein to generate conformations of the receptor for ensemble-docking calculations
Aortic valve replacement for paraprosthetic leak after transcatheter implantation
No full textConversion to surgical aortic valve replacement (AVR) has been described as a complication following transcatheter aortic valve implantation. This complication occurs in up to 8% of cases and, to the best of our knowledge, preoperative data and surgical outcomes of such patients have not been properly evaluated. Mild paraprosthetic regurgitation is commonly observed after transcatheter aortic valve implantation and usually leads to a benign clinical course. Unequal distribution of valve calcifications is described as a potential mechanism. We report a case of a perioperative paraprosthetic regurgitation that underwent successful urgent surgical AVR and review the incidence and results of paraprosthetic leaks following transcatheter implantation. © 2011 Wiley Periodicals, Inc
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