Consolidación y fragmentación de la investigación de la comunicación en México, 1987-1997

Este artículo expone de una manera breve y general las conclusiones del trabajo de investigación sobre los procesos de estructuración del campo de la investigación académica de la comunicación en México de 1987 a 1997. El acercamiento empírico exploratorio de este trabajo supone el acopio y la sistematización de datos sobre la producción mexicana de conocimiento sobre la comunicación y sus condiciones contextuales; sobre sus productores, tanto individuales como institucionales; y sobre sus productos objetivos, especialmente las publicaciones académicas. A partir de los resultados del análisis de toda esta información, se construyó un modelo heurístico de las determinaciones socioculturales de la estructuración del campo desde la década de 1960 hasta la de 1990, que permite formular la "doble disyuntiva" que se enfrentó en los años noventa para alcanzar la legitimación académica y social

Mitral Valve Patient-Specific Finite Element Modeling from Cardiac MRI: Application to an Annuloplasty Procedure

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Finite element modelling of the tricuspid valve : a preliminary study

The incomplete efficacy of current surgical repair procedures of the tricuspid valve (TV) demands a deeper comprehension of the physiological TV biomechanics. To this purpose, computational models can provide quantitative insight into TV biomechanical response and allow analysing the role of each TV substructure. We present here a three-dimensional finite element model of the tricuspid valve that takes into account most of its peculiar features. Experimental measurements were performed on human and porcine valves to obtain a more detailed TV anatomical framework. To overcome the complete lack of information on leaflets mechanical properties, we performed a sensitivity analysis on the parameters of the adopted non-linear hyperelastic constitutive model, hypothesizing three different parameter sets for three significant collagen fibre distributions. Results showed that leaflets\u2019 motion and maximum principal stress distribution were almost insensitive to the different material parameters considered. Highest stresses (about 100 kPa) were located near the annulus of the anterior and septal leaflets, while the posterior leaflet experienced lower stresses (about 55 kPa); stresses at the commissures were nearly zero. Conversely, changes in constitutive parameters deeply affected leaflets\u2019 strains magnitude, but not their overall pattern. Strains computed assuming that TV leaflets tissue are reinforced by a sparse and loosely arranged network of collagen fibres fitted best experimental data, thus suggesting that this may be the actual microstructure of TV leaflets. In a long-term perspective, this preliminary study aims at providing a starting point for the development of a predictive tool to quantitatively evaluate TV diseases and surgical repair procedures

Finite element modelling of the tricuspid valve: A preliminary study.

The incomplete efficacy of current surgical repair procedures of the tricuspid valve (TV) demands a deeper comprehension of the physiological TV biomechanics. To this purpose, computational models can provide quantitative insight into TV biomechanical response and allow analysing the role of each TV substructure. We present here a three-dimensional finite element model of the tricuspid valve that takes into account most of its peculiar features. Experimental measurements were performed on human and porcine valves to obtain a more detailed TV anatomical framework. To overcome the complete lack of information on leaflets mechanical properties, we performed a sensitivity analysis on the parameters of the adopted non-linear hyperelastic constitutive model, hypothesizing three different parameter sets for three significant collagen fibre distributions. Results showed that leaflets\u2019 motion and maximum principal stress distribution were almost insensitive to the different material parameters considered. Highest stresses (about 100 kPa) were located near the annulus of the anterior and septal leaflets, while the posterior leaflet experienced lower stresses (about 55 kPa); stresses at the commissures were nearly zero. Conversely, changes in constitutive parameters deeply affected leaflets\u2019 strains magnitude, but not their overall pattern. Strains computed assuming that TV leaflets tissue are reinforced by a sparse and loosely arranged network of collagen fibres fitted best experimental data, thus suggesting that this may be the actual microstructure of TV leaflets. In a long-term perspective, this preliminary study aims at providing a starting point for the development of a predictive tool to quantitatively evaluate TV diseases and surgical repair procedures

Impact of modeling fluid-structure interaction in the computational analysis of aortic root biomechanics.

Numerical modeling can provide detailed and quantitative information on aortic root (AR) biomechanics,improving the understanding of AR complex pathophysiology and supporting the development of moreeffective clinical treatments.From this standpoint, fluid\u2013structure interaction (FSI) models are currently the most exhaustive andpotentially realistic computational tools. However, AR FSI modeling is extremely challenging and compu-tationally expensive, due to the explicit simulation of coupled AR fluid dynamics and structural response,while accounting for complex morphological and mechanical features.We developed a novel FSI model of the physiological AR simulating its function throughout the entirecardiac cycle. The model includes an asymmetric MRI-based geometry, the description of aortic valve (AV)non-linear and anisotropic mechanical properties, and time-dependent blood pressures. By comparisonto an equivalent finite element structural model, we quantified the balance between the extra informationand the extra computational cost associated with the FSI approach.Tissue strains and stresses computed through the two approaches did not differ significantly. The FSIapproach better captured the fast AV opening and closure, and its interplay with blood fluid dynamicswithin the Valsalva sinuses. It also reproduced the main features of in vivo AR fluid dynamics. However, theFSI simulation was ten times more computationally demanding than its structural counterpart. Hence,the FSI approach may be worth the extra computational cost when the tackled scenarios are stronglydependent on AV transient dynamics, Valsalva sinuses fluid dynamics in relation to coronary perfusion(e.g. sparing techniques), or AR fluid dynamic alterations (e.g. bicuspid AV)

Feasibility of the evaluation of the mitral valve by patient-specific computational model based on cardiac MRI.

To test the feasibility of extracting quantitative information about MV and PMs from cardiac magnetic resonance (CMR) imagin