A theoretical model of the endothelial cell morphology due to different waveforms

Endothelial cells are key units in the regulatory biological process of blood vessels. They represent an interface to transmit variations on the fluid dynamic changes. They are able to adapt its cytoskeleton, by means of microtubules reorientation and F-actin reorganization, due to new mechanical environments. Moreover, they are responsible for initiating a huge cascade of biological processes, such as the release of endothelins (ET-1), in charge of the constriction of the vessel and growth factors such as TGF-ß and PDGF. Although a huge efforts have been made in the experimental characterization and description of these two issues the computational modeling has not gained such an attention. In this work we study the 3D remodeling of endothelial cells based on the main features of blood flow. In particular we study how different oscillatory shear index and the time average wall shear stresses modify the endothelial cell shape. We found our model fitted the experimental works presented before in in vitro studies. We also include our model within a computational fluid dynamics simulation of a carotid artery to evaluate endothelial cell shape index which is a key predictor of atheroma plaque formation. Moreover, our approach can be coupled with models of collagen and smooth muscle cell growth, where remodeling and the associated release of chemical substance are involved.Peer ReviewedPostprint (author's final draft

Free convection boundary layers driven by exothermic surface reactions: critical ambient temperatures

A model for the free convection boundary-layer flow near a forward stagnation point driven by heating from a surface on which there is a catalytic reaction is discussed. The governing equations are mude dimensionless so as to highlight the ambient temperature with themain emphasis being to determine critical ambient temperatures. The basic model is then reduced to a standard free convection problem by a transformation of variables from which bifurcation diagrams (plots of a dimensionless surface temperature against a dimensionless ambient temperature) can be constructed. These show a hysteresis bifurcation, the position of which can be readily deduced. A feature of the present formulation is the occurrence of disjoint bifurcation diagrams whereby the upper solution branch becomes separated from the lower solution branches. This aspect is also discussed in detail

On the use of the Bingham statistical distribution in microsphere-based constitutive models for arterial tissue

Constitutive models for arterial tissue have been an active research field during the last years. The main micro-constituents of blood vessels are different types of cells and the extra-cellular matrix formed by an isotropic high water content ground substance and a network composed of elastin and collagen fibres. Usually the arterial tissue has been modelled as a hyperelastic material within the framework of continuum mechanics, whereas inclusion of structural tensors into constitutive laws is the most widely used technique to introduce the anisotropy induced by the fibres. Though the different existing fibre bundles present a clear preferential direction, the dispersion inherent to biological tissue advices using of constitutive models including representative structural information associated to the spatial probabilistic distribution of the fibres. Lately, microsphere-based models have demonstrated to be a powerful tool to incorporate this information. The fibre dispersion is incorporated by means of an Orientation Density Function (ODF) that weights the contribution of each fibre in each direction of the micro-sphere. In previous works the rotationally symmetric von Mises ODF was successfully applied to the modelling of blood vessels. In this study, the inclusion of the Bingham ODF into microsphere-based model is analysed. This ODF exhibits some advantages with respect to the von Mises one, like a greater versatility and a comparable response to simple tension and equibiaxial tension tests.Peer ReviewedPostprint (author's final draft

Organic vs Conventional Suckling Lamb Production: Product Quality and Consumer Acceptance

Samples of suckling lambs (n=40) of two breeds reared under conventional and organic conditions were analysed to asses physico-chemical characteristics, including instrumental texture, and nutritional quality in terms of fatty acid composition. Consumer acceptance was also studied using the home-use test. Results revealed that organic suckling lamb meat is healthier as shown by the lower saturated fatty acid levels, the higher polyunsaturated fatty acid contents and the higher 6/3 ratiko. The organic meat had lower instrumental hardness, received higher scores in all sensory parameters, and had statistically better fat sensation and higher ratings for overall liking. These results lend support to the notion among consumers that organic products are healthier and tastier

Consumer Appreciation of Carcass Quality of Organic vs Conventional Suckling Lamb Production

Carcass characteristics of sucking lambs (n= 40) of two breeds reared under conventional and organic conditions were analysed including objective and subjective parameters for fatness and conformation, meat and fat colour. Consumer acceptance was also studied using the home-use test. Results showed that the characteristics of the carcass of suckling lamb were similar for both types of production systems pointing out that organic production system did not affect fatness or muscle development. However, organic meat was darker (higher L* and a* values) probably related with the higher amount of exercise, although fat was not more yellow. In contrast consumers did not consider organic meat darker and there were not significant differences in appearance related with the similar conformation. These results reflect that consumer perceive organic meat as at least as good as conventional production not only regarding environmental quality but also regarding carcass quality

Análisis funcional de los buriles de la cueva de Zatoya (Navarra)

El análisis de huellas de uso de un conjunto de buriles que entregaron las excavaciones de la cueva de Zatoya ha proporcionado una interesante información que nos ha permitido profundizar en la funcionalidad y gestión de este utillaje. A través del estudio traceológico hemos podido reconstruir las fases de los procesos de trabajo en materias óseas en los que intervinieron dichos instrumentos.---------- A microwear analisis of selected burins came from the excavations of Zatoya’s cave has provided an interesting information about the function and management of this tools. Through this survey we were able to reconstruct the stage of work bone or antler processing which intervened the above implements

Accelerated Simulation of P Systems on the GPU: A Survey

The acceleration of P system simulations is required increasingly, since they are at the core of model verification and validation processes. For this purpose, GPU computing is an alternative to more classic approaches in Parallel Computing. It provides a manycore platform with a level of high parallelism at a low cost. In this paper, we survey the developments of P systems simulators using the GPU, and analyze some performance considerations.Ministerio de Economía y Competitividad TIN2012- 37434Junta de Andalucía P08-TIC-0420

El mercado entre la sociabilidad y el conflicto

Different opinions are expounded about the relation between market and political community. This relation is two-sided. On the one hand, it is collaborative; on the other, it is conflictive. Attempts to harmonize the individual interests mechanically have failed both theoretically and in practice

Razón autónoma y modelos matemáticos de la acción

El supuesto de la autonomía de la razón obliga a recurrir a la Matemática para explicar su hipotética practicidad. Esto plantea problemas nada sencillos de resolver. Se revisa brevemente el reciente enfoque de la racionalidad limitada, sus potencialidades y debilidades. Se cuestiona la posibilidad misma de una teoría pura de la acción

Don y desarrollo, bases de la economía.

El autor presenta algunas reflexiones y conclusiones que se pueden extraerde la lectura de Caritas in veritate, desde la perspectiva de la filosofía de la economía. En un primer momento se subraya, a la luz de la encíclica, la importancia de considerar el hombre como un don en sí mismo. A partir de ahí, se explica la concepción adecuada del desarrollo, también desde la óptica del don. Desde esas coordenadas, la teoría económica es interpelada para introducir la lógica del don y del amor en la comprensión de la acción económica, huyendo así del peligro de una racionalidad mutilada. En particular se sugiere la conexión entre don y contrato para hacer posible el auténtico desarrollo. Documentos del Instituto de Antropología y Ética, número 1