Exploratory Study of Ventilated Flows About Yawed Surface-Piercing Struts

Reported herein are the results of observations and measurements made in connection with a study of the phenomenon of the development of atmosphere-connected cavities about surface-piercing struts. Conditions for the existence of such ventilated flows which have been derived from the experimental data are presented. In addition, certain broad conclusions pertinent to model testing and full-scale design are reached. Further experimentation to define the inception of ventilation as a function of boundary-layer state or Reynolds number is required

Aplicación del método de los elementos finitos en estudios de diferenciación craneofacial.

The object of the present study was: (a) to demonstrate that the Finite Elemental M'ethocl (FEM) is an useful way to perforo! studies on craniofacial growth and development, and (b) to incorporate FEM as an adequate method in studies of craniological anthropology, a's well as in other fields related to cephalo-facial development and its alterations. The outstanding feature of this methocl is that such stuclies may be done avoiding any type of arbitrary reference systems. This faet will allow to solve the main methodological eonstraint in eraniology, as ",ell as in all fields of biology in which eranial tracing constitutes a valid descriptive, comparative and analytical teehnique. As an example, a study performed on experimental Iaboratory rats is included, in whieh a cranial analysis by the FEM was performed.El presente trabajo tiene por objeto: (a) demostrar la aplicabilidad del método de los ELementos Finitos (MEF) a los estudios de crecimiento y diferenciación craneofacial; (b) fundamentar la incorporación del MEF como método válido en craneografía antropológica y disciplinas relacionadas. Esta innovación implica prescindir de los procedimientos clásicos de orientación según sistemas cle líneas, puntos y/o planos (Francfort, Broca, basicraneal, vestibular, ete.) usualmente aplicados en craneología convencional. Se resuelve así la principal limitación de los estudios basados en representaciones gráficas como método de descripción, comparación y análisis. Se incluye a modo de ejemplo, un estudio realizado en ratas experimentales de laboratorio, cuyo análisis craneográfico fue desarrollado mediante el MEF

A theoretical model of inflammation- and mechanotransduction- driven asthmatic airway remodelling

Inflammation, airway hyper-responsiveness and airway remodelling are well-established hallmarks of asthma, but their inter-relationships remain elusive. In order to obtain a better understanding of their inter-dependence, we develop a mechanochemical morphoelastic model of the airway wall accounting for local volume changes in airway smooth muscle (ASM) and extracellular matrix in response to transient inflammatory or contractile agonist challenges. We use constrained mixture theory, together with a multiplicative decomposition of growth from the elastic deformation, to model the airway wall as a nonlinear fibre-reinforced elastic cylinder. Local contractile agonist drives ASM cell contraction, generating mechanical stresses in the tissue that drive further release of mitogenic mediators and contractile agonists via underlying mechanotransductive signalling pathways. Our model predictions are consistent with previously described inflammation-induced remodelling within an axisymmetric airway geometry. Additionally, our simulations reveal novel mechanotransductive feedback by which hyper-responsive airways exhibit increased remodelling, for example, via stress-induced release of pro-mitogenic and procontractile cytokines. Simulation results also reveal emergence of a persistent contractile tone observed in asthmatics, via either a pathological mechanotransductive feedback loop, a failure to clear agonists from the tissue, or a combination of both. Furthermore, we identify various parameter combinations that may contribute to the existence of different asthma phenotypes, and we illustrate a combination of factors which may predispose severe asthmatics to fatal bronchospasms

Handbook of bioengineering

New Yorkxii, 687 p.; 23 c