COAST will develop an innovative concept, Complex Automata, offering a new framework for multi-scale, multi-science simulations. A Complex Automaton is a scalable hierarchical aggregation of Cellular Automata and agent-based models with appropriate couplings. The COAST framework will be validated on a challenging biomedical application aimed at treatment of coronary artery disease.

Complex Automata, a generalization of Cellular Automata, facilitate coupling of all spatial and temporal scales present in a complex system. The issue of subsystem coupling will be addressed using a scale splitting methodology to discover effective simulation strategies. The nature of the coupling and mutual distance on a scale separation map will be key factors to foster simulations crossing length and time scales. The framework also includes agent-based models, as a mechanism to merge Euclidean with Lagrangian worldviews. A theoretical formulation of the proposed framework will be developed so as to offer an effective modelling language to describe complex systems.

The biomedical application is targeted at drug-eluting stents used to prevent re-stenosis of coronary arteries. It amounts to coupling biological processes acting on the micron scale up to haemodynamic processes acting on the centimetre scale (hydrodynamics, advection-reaction-diffusion, fluid-structure interaction, particle transport in boundary layers, tissue growth, and single cell response). These processes also involve widely separated time scales, from seconds to months. The resulting simulation will be validated with available in-vivo data and be used to study several designs of drug-eluting stents.

COAST will result in a powerful complex systems modelling methodology, opening the way for a formal description of multi-scale multi-science simulations. In addition, it will advance the understanding of complex biomedical systems, and provide new capabilities in computer-aided medicine and many other key applications.

Objectives of COAST

The objectives of COAST are to

1. develop a multi-scale, multi-science framework coined Complex Automata for modelling and simulation of complex systems based on hierarchical aggregation of coupled Cellular Automata and agent based models;
2. develop a mathematical framework for Complex Automata, allowing transformation into a generic modelling and simulation framework;
3. identify basic ways in which information can be shared between sub-models within a Complex Automaton;
4. develop a modelling and simulation software framework;
5. validate the Complex Automaton framework by applying it to a very challenging and highly relevant biomedical application, related to treatment of coronary artery diseases;
6. model the process of tissue re-growth after stent placement as a Complex Automaton, implement it in the Complex Automata environment, and run simulations to optimise design of drug-eluting stents.