Impacto de las nuevas tecnologías en la política de competencia: big data y big analitics

Se realiza una recopilación rigurosa de información sobre Biga data y problemas de competencia, mencionando los casos más relevantes, con el fin de que sirva de punto de partida para futuros estudios en esta materia. Con ello, trataremos de cumplir con los siguientes objetivos intermedios: a) Realizar una introducción al mundo de la economía digital. b) Estudiar los nuevos modelos de negocios basados en Internet. c) Análisis de casos e impacto sobre la política de competencia. d) Propuestas de mejoras de regulación en el sector, favorecedoras de competenciaUniversidad de Sevilla. Máster Universitario en Consultoría Económica y Análisis Aplicad

A structural approach including the behavior of collagen cross-links to model patient-specific human carotid arteries

The final publication is available at Springer via http://dx.doi.org/10.1007/s10439-014-0995-7The objective of this work is to develop a remodeling model for biological matter coupling two different processes in a 3D framework: reorientation of the preferential direction of a given fibered structure and reorientation of the fibrils or filaments that make up such a structure. This work uses the microsphere-based approach to take into account the micro mechanics involved in biological fibered structures regarding both their passive behavior and the reorientation of their micro constituents. Moreover, the macro behavior of the material as a whole is obtained by means of homogenizing the underlying micro response. We associate the orientation space of the integration directions to the physical space of micro-fibrils. To approximate the directional distribution of the fibrils within each fiber bundle, a Bingham probability orientation density function is introduced into the Helmholtz energy function. With all these assumptions, the problem is studied from an energetic point of view, describing the dissipation inherent to remodeling processes, and the evolution equations for both reorientations (change in preferential direction of the network and change in shape of the fibril distribution) re obtained. The model is included in a finite element code which allows computing different geometries and boundary value problems. This results in a complete methodology for characterizing the reorientation evolution of different fibered biological structures, such as cells. Our results show remodeling of fibered structures in two different scales, presenting a qualitatively good agreement with experimental findings in cell mechanics. Hierarchical structures align in the direction of the maximum principal direction of the considered stimulus and narrow in the perpendicular direction. The dissipation rates follows predictable trends although there are no experimental findings to date for comparison. The incorporation of metabolic processes and an insight into cell-oriented mechano-sensing processes can help to overcome the limitations involved.Peer ReviewedPostprint (author's final draft

Computational modeling of hypertensive growth in the human carotid artery

The final publication is available at Springer via http://dx.doi.org/10.1007/s00466-013-0959-zArterial hypertension is a chronic medical condition associated with an elevated blood pressure. Chronic arterial hypertension initiates a series of events, which are known to collectively initiate arterial wall thickening. However, the correlation between macrostructural mechanical loading, microstructural cellular changes, and macrostructural adaptation remains unclear. Here, we present a microstructurally motivated computational model for chronic arterial hypertension through smooth muscle cell growth. To model growth, we adopt a classical concept based on the multiplicative decomposition of the deformation gradient into an elastic part and a growth part. Motivated by clinical observations, we assume that the driving force for growth is the stretch sensed by the smooth muscle cells. We embed our model into a finite element framework, where growth is stored locally as an internal variable. First, to demonstrate the features of our model, we investigate the effects of hypertensive growth in a real human carotid artery. Our results agree nicely with experimental data reported in the literature both qualitatively and quantitatively.Peer ReviewedPostprint (author's final draft

Failure damage mechanical properties of thoracic and abdominal porcine aorta layers and related constitutive modeling: phenomenological and microstructural approach

Despite increasing experimental and analytical efforts to investigate the irreversible effects of arterial tissue failure, the underlying mechanisms are still poorly understood. The goal of this study was to characterize the failure properties of the intact wall and each separated layer (intima, media, and adventitia) of the descending thoracic and infrarenal abdominal aorta and to test the hypothesis that the failure properties of layer-separated tissue depend on the location of the aorta. To test this hypothesis, we performed uniaxial tests to study the mechanical behavior of both intact and layer-separated porcine aortic tissue samples taken from descending thoracic and infrarenal abdominal aorta until complete failure. The fracture stress is higher in the infrarenal abdominal aorta than in the equivalent descending thoracic aorta. It was also found that the extrapolation of the elastic mechanical properties from the physiological to the supra-physiological regime for characterizing the mechanical response of the aorta would be inappropriate. Finally, we report values of constitutive parameters using phenomenological and microstructural damage models based on continuum damage mechanics theory. The phenomenological damage model gives an excellent fit to the experimental data compared to the microstructural damage model. Although the fitting results of the phenomenological model are better, the microstructural models can include physically motivated aspects obtained from experiments

Over length quantification of the multiaxial mechanical properties of the ascending, descending and abdominal aorta using Digital Image Correlation

In this paper, we hypothesize that the biaxial mechanical properties of the aorta may be dependent on arterial location. To demonstrate any possible position-related difference, our study analyzed and compared the biaxial mechanical properties of the ascending thoracic aorta, descending thoracic aorta and infrarenal abdominal aorta stemming from the same porcine subjects, and reported values of constitutive parameters for well-known strain energy functions, showing how these mechanical properties are affected by location along the aorta. When comparing ascending thoracic aorta, descending thoracic aorta and infrarenal abdominal aorta, abdominal tissues were found to be stiffer and highly anisotropic. We found that the aorta changed from a more isotropic to a more anisotropic tissue and became progressively less compliant and stiffer with the distance to the heart. We observed substantial differences in the anisotropy parameter between aortic samples where abdominal samples were more anisotropic and nonlinear than the thoracic samples. The phenomenological model was not able to capture the passive biaxial properties of each specific porcine aorta over a wide range of biaxial deformations, showing the best prediction root mean square error e=0.2621 for ascending thoracic samples and, especially, the worst for the infrarenal abdominal samples e=0.3780. The micro-structured model with Bingham orientation density function was able to better predict biaxial deformations (e=0.1372 for ascending thoracic aorta samples). The root mean square error of the micro-structural model and the micro-structured model with von Mises orientation density function were similar for all positions

Coronary artery properties in atherosclerosis: A deep learning predictive model

In this work an Artificial Neural Network (ANN) was developed to help in the diagnosis of plaque vulnerability by predicting the Young modulus of the core (Ecore) and the plaque (Eplaque) of atherosclerotic coronary arteries. A representative in silico database was constructed to train the ANN using Finite Element simulations covering the ranges of mechanical properties present in the bibliography. A statistical analysis to pre-process the data and determine the most influential variables was performed to select the inputs of the ANN. The ANN was based on Multilayer Perceptron architecture and trained using the developed database, resulting in a Mean Squared Error (MSE) in the loss function under 10–7, enabling accurate predictions on the test dataset for Ecore and Eplaque. Finally, the ANN was applied to estimate the mechanical properties of 10,000 realistic plaques, resulting in relative errors lower than 3%

Cuerpos sicariados: el espacio de la violencia en La Virgen de los sicarios de Fernando Vallejo

El presente estudio explora las relaciones y significaciones del cuerpo en el espacio de la violencia, en la novela La virgen de los sicarios (1994) del escritor colombiano Fernando Vallejo. En esta obra la violencia expresa su naturaleza territorial; necesita espacios simbólicos, físicos, corporales que demarcar, rasgar, fracturar. Esta configuración socioespacial y corporal, no puede sino ser entendida en relación a la materialidad del poder ejercido sobre el cuerpo (Foucault; 1980). Y es precisamente, en la figura del sicario en donde esta materialidad da forma a subjetividades que devienen en sujeción (Butler 2010), en un espacio cercado por lo que podríamos definir como “micropolíticas de la violencia”.The present study explores the relationships and significances of the body in the space of the violence sicarial, in the novel Our Lady of the Assassins (1994) of the Colombian writer Fernando Vallejo. In this work the expressed violence their territorial nature; he/she needs symbolic and physical spaces that to demarcate, to rip, to fracture. Starting from it, the relationship space-body you vital restitution: spaces of life or death. This configuration socioespacial and corporal, he/she is not able to but being understood in relation to the materiality of the power exercised on the body (Foucault; 1980). And it is in fact, in the assassin's figure where this materiality gives form to subjectivities that become in subjection (Butler 2010), in a walled space for what we could define as "micropolitics of the violence.

Is location a significant parameter in the layer dependent dissection properties of the aorta?

Proper characterisation of biological tissue is key to understanding the effect of the biomechanical environment in the physiology and pathology of the cardiovascular system. Aortic dissection in particular is a prevalent and sometimes fatal disease that still lacks a complete comprehension of its progression. Its development and outcome, however, depend on the location in the vessel. Dissection properties of arteries are frequently studied via delamination tests, such as the T-peel test and the mixed-mode peel test. So far, a study that performs both tests throughout different locations of the aorta, as well as dissecting several interfaces, is missing. This makes it difficult to extract conclusions in terms of vessel heterogeneity, as a standardised experimental procedure cannot be assured for different studies in literature. Therefore, both dissection tests have been here performed on healthy porcine aortas, dissecting three interfaces of the vessels, i.e., the intima-media, the media-adventitia and the media within itself, considering different locations of the aorta, the ascending thoracic aorta (ATA), the descending thoracic aorta and the infrarenal abdominal aorta (IAA). Significant differences were found for both, layers and location. In particular, dissection forces in the ATA were the highest and the separation of the intima-media interface required significantly the lowest force. Moreover, dissection in the longitudinal direction of the vessel generally required more force than in the circumferential one. These results emphasise the need to characterise aortic tissue considering the specific location and dissected layer of the vessel

Atheroma plaque vulnerability based in a 3D idealized parametric geometry

Las enfermedades cardiovasculares constituyen la primera causa de mortalidad en los países desarrollados, así como en la práctica totalidad de los países en desarrollo. Dentro de las patologías cardiovasculares, una de las enfermedades que mas muertes causan hoy en día es la aterosclerosis. Dicha enfermedad consiste en la degeneración progresiva y crónica del engrosamiento y endurecimiento de la pared arterial como resultado de la acumulación de depósitos de grasa, colesterol y otras sustancias en la pared interna del vaso. Estas sustancias forman estructuras duras llamadas placas de ateroma y en ellas se puede diferenciar diferentes composiciones; calcificación, lípidos y tejido fibroso. Con el tiempo, si estas placas son vulnerables pueden romperse y provocar la formación de coagulos sanguíneos que bloquean el flujo sanguíneo desencadenando diferentes eventos tales como infartos, trombos o gangrena. La importancia de identificar la placa vulnerable antes de su rotura sigue siendo un reto para la medicina. Actualmente el diagnostico se puede realizar por métodos no invasivos, tales como es determinar la presencia de factores de riesgo, marcadores de vulnerabilidad de la placa, y métodos invasivos como es la angioscopia. Aunque existen varios métodos, no existe uno que nos dé toda la información morfológica y de actividad de la placa necesaria. El objetivo principal de este trabajo es el estudio y modelado de vasos sanguíneos, concretamente de una coronaria, afectados por aterosclerosis. Para ello, se ha desarrollado un estudio parametrico en tres dimensiones (3D) de los factores geométricos en la vulnerabilidad de la placa de ateroma y de la influencia de las tensiones residuales. Los modelos en 3D nos permiten incluir los efectos producidos por las tensiones residuales. Con dichos modelos se van a estudiar tres situaciones diferentes; sin tensiones residuales, considerando tensiones residuales en dirección longitudinal y por ultimo, considerando tensiones residuales tanto en dirección longitudinal como circunferencial. De este modo, se podra identicar el papel que juegan las tensiones residuales en la vulnerabilidad de la placa de ateroma y definir límites de vulnerabilidad para cada uno de los parámetros considerados. Los modelos se han simulado mediante elementos finitos con el software comercial ABAQUS. Los resultados obtenidos, nos permiten ir un paso mas allá en el diagnóstico preventivo y en la planicación preoperatoria en aplicaciones cardiovasculares. Con el fin de validar el modelo, se ha reconstruido mediante el software comercial MIMICS una geometría real a partir de un IVUS (ultrasonido intravascular) de un paciente adulto con placa de ateroma. Tras la reconstrucción se han medido los parámetros estudiados en la geometra real y la hemos comparado con el correspondiente caso paramétrico de parametros similares

Análisis mecánico de placas de ateroma en fase de crecimiento positivo: Estudio de la influencia de la longitud de la placa

Cuando el nivel de colesterol en sangre es suficientemente elevado, los lípidos que lo conforman logran pasar a través de las paredes de los vasos sanguíneos, es entonces cuando las células macrófagas conocidas como linfocitos fagocitan las moléculas de colesterol para proteger la pared arterial, formando las placas de ateroma, las cuales pueden provocar una obstrucción de las arterias, dando lugar a una angina de pecho, o en el peor de los casos, en un infarto. Este estudio tiene como objetivo analizar la influencia de la longitud de dicha placa, los materiales de la pared arterial y la importancia de la consideración o no del núcleo lipídico en las tensiones y deformaciones principales y tangenciales, las cuales en la actualidad son objeto de estudio como parámetro de detección precoz para evitar una muerte súbita por necrosis isquémica (infarto). En el proceso de creación de cada simulación, primero se partirá de diversos estudios para obtener funciones y leyes matemáticas que reproduzcan la evolución de la geometría de la placa y crear así las diversas secciones arteriales. Posteriormente estas funciones han sido introducidas en un programa destinado al diseño y creación de geometrías, que han sido importadas en un programa de cálculo para estudiar su comportamiento mecánico