1,720,956 research outputs found
Impact of Tissue Damage and Hemodynamics on Restenosis Following Percutaneous Transluminal Angioplasty: A Patient-Specific Multiscale Model.
Full text linkMultiscale agent-based modeling frameworks have recently emerged as promising mechanobiological models to capture the interplay between biomechanical forces, cellular behavior, and molecular pathways underlying restenosis following percutaneous transluminal angioplasty (PTA). However, their applications are mainly limited to idealized scenarios. Herein, a multiscale agent-based modeling framework for investigating restenosis following PTA in a patient-specific superficial femoral artery (SFA) is proposed. The framework replicates the 2-month arterial wall remodeling in response to the PTA-induced injury and altered hemodynamics, by combining three modules: (i) the PTA module, consisting in a finite element structural mechanics simulation of PTA, featuring anisotropic hyperelastic material models coupled with a damage formulation for fibrous soft tissue and the element deletion strategy, providing the arterial wall damage and post-intervention configuration, (ii) the hemodynamics module, quantifying the post-intervention hemodynamics through computational fluid dynamics simulations, and (iii) the tissue remodeling module, based on an agent-based model of cellular dynamics. Two scenarios were explored, considering balloon expansion diameters of 5.2 and 6.2 mm. The framework captured PTA-induced arterial tissue lacerations and the post-PTA arterial wall remodeling. This remodeling process involved rapid cellular migration to the PTA-damaged regions, exacerbated cell proliferation and extracellular matrix production, resulting in lumen area reduction up to 1-month follow-up. After this initial reduction, the growth stabilized, due to the resolution of the inflammatory state and changes in hemodynamics. The similarity of the obtained results to clinical observations in treated SFAs suggests the potential of the framework for capturing patient-specific mechanobiological events occurring after PTA intervention
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
A patient-specific multiscale agent-based modeling framework of restenosis after balloon angioplasty in a superficial femoral artery
No full textLAUREA MAGISTRALELa restenosi è la principale causa di fallimento dell'angioplastica percutanea transluminale (percutaneous transluminal angioplasty, PTA) eseguita sulle arterie femorali superficiali. Consiste nel progressivo restringimento del lume a causa di un'alterata attività proliferativa e sintetica delle cellule che porta a una crescita eccessiva del tessuto. Il danno meccanico indotto dalla PTA e l'alterazione dell'emodinamica giocano un ruolo chiave nello sviluppo della restenosi, poiché concorrono a innescare e mantenere la risposta infiammatoria della parete arteriosa. I modelli computazionali multiscala che integrano sia approcci al continuo sia basati su agenti sono strumenti molto utili nello studio della ristenosi, in quanto il rimodellamento indotto dall’angioplastica è causato da processi complessi che agiscono sia a livello tissutale che cellulare. Il presente lavoro di tesi propone un framework multiscala paziente-specifico per lo studio della restenosi che associa ad un modello strutturale a elementi finiti (finite element modeling, FEM) e a simulazioni fluidodinamiche computazionali (computational fluid-dynamics, CFD) un modello basato su agenti (agent-based model, ABM) del rimodellamento del tessuto arterioso. Il modulo di angioplastica è stato usato per simulare l’intervento su un modello di arteria femorale superficiale specifico del paziente, calcolare il danno meccanico indotto dall'intervento e ricostruire la geometria del vaso ottenuta in due scenari che differivano solamente per la dimensione e la massima espansione del pallone da angioplastica utilizzato. Le simulazioni CFD hanno fornito la distribuzione dello sforzo di taglio della parete. Il modello ad agenti 2D ha simulato la dinamica delle cellule e della matrice extracellulare (extra-cellular matrix, ECM) e il conseguente rimodellamento della parete arteriosa in più sezioni trasversali del vaso nei due mesi successivi all'intervento. Il framework proposto ha riprodotto con successo la crescita del tessuto arterioso come funzione di stimoli meccanici ed emodinamici. Inoltre, ha permesso di far luce sulle differenze in termini di restenosi causate dall’utilizzo di diversi gradi di espansione del pallone nel corso della procedura endovascolare.Restenosis is the major limitation of percutaneous transluminal angioplasty (PTA) performed on superficial femoral arteries (SFAs). It consists of the progressive lumen re-narrowing because of altered cellular proliferative and synthetic activities leading to excessive tissue growth. PTA-induced mechanical damage and altered hemodynamics have been recognized to play a key role in the development of restenosis, because they concur to induce and maintain the inflammatory response of the arterial wall. Computational multiscale models integrating continuous- and agent-based approaches can provide powerful insights into the study of the complex events that act, both at the tissue and cellular scale, in the arterial wall remodelling process provoked by PTA. The present thesis work proposes a patient-specific multiscale framework of restenosis that couples a structural finite element model (FEM) and computational fluid dynamics (CFD) simulations with an agent-based model (ABM) of tissue remodelling. The angioplasty module simulated the PTA procedure on a patient-specific SFA model and computed the final vessel geometry and the intervention-induced mechanical damage in two scenarios differing for the dimension and maximum expansion of the used PTA balloon. The CFD simulations provided the wall shear stress (WSS) distribution along the luminal surface. The 2D ABM simulated cell and extracellular matrix (ECM) dynamics and the resulting arterial wall remodelling in multiple vessel cross-sections. The proposed framework successfully reproduced the intimal tissue growth as a function of both mechanical and hemodynamic stimuli. Furthermore, it may help to clarify the varying levels of restenosis that occur as a result of different degrees of balloon expansion during the endovascular procedure
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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