On thermodynamic modeling and the role of the second law of thermodynamics in geophysics

The article contains a brief review of elements of thermodynamic modeling in theoretical geophysics. We motivate the existence of the second law of thermodynamics in macroscopic theoretical physics and demonstrate its evaluation. In particular we show its consequences in the construction of constitutive laws for a two-component poroelastic medium. This construction is also related to microstructural properties verified by means of the second law

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

Cauchy and the modern mechanics of continua

SUMMARY. — Some of Cauchy's major works are shown to have served as bases and inspiration for the modern development of rigorous continuum mechanics by Walter Noll and his followers.RÉSUMÉ. — On démontre que quelques-uns des travaux de Cauchy ont fourni les bases et l'inspiration pour le développement moderne de la mécanique rigoureuse des milieux continus par Walter Noll et ceux qui suivirent ses concepts et méthodes.Truesdell Clifford A. Cauchy and the modern mechanics of continua. In: Revue d'histoire des sciences, tome 45, n°1, 1992. pp. 5-24