OpenCMISS software for FieldML models
At the heart of physical laws is the concept of continuous fields – and much of physiology is the interaction between these fields and the molecules that support life. Examples are the relationship between a continuous temperature field and the energy of its constituent particles, or a pressure field representing the energy density (J/m^3) of energetic particles, or the oxygen concentration field in a tissue and its relationship with oxygen sensitive proteins. The ‘particles’ in physiology are molecules (proteins, carbohydrates, lipids) and of course the complexity of their formation, structure and interaction is what biomedical science and drug discovery is all about. Physiological function and the symptoms of disease, however, appear at the tissue/organ scale and the field laws of physics are an essential component of the physiological phenotype. There are only four equations, or equation systems, needed to capture the laws of physics (conservation of mass, linear and angular momentum, and energy, respectively) at the scale of continuous fields. These are the Navier-Stokes equations (dealing with fluid mechanics), the equations of finite elasticity (dealing with the mechanical behaviour of solid materials), Maxwell’s equations (dealing with the behaviour of electro-magnetic) and reaction-diffusion equations (dealing with conservation of mass for chemical species represented by their concentration fields). We are developing a modelling standard (FieldML) and software libraries that support both simulation and visualisation based on this standard (OpenCMISS:Iron and OpenCMISS:Zinc). Some examples of FieldML models being used in the MedTech CoRE are shown below. See next.opencmiss.org for details.