Complex Systems in Biology and Soft Sciences

Book excerpt: This thesis tackles the challenging aim of developing a mathematical theory of living systems with focus on hyperbolic and kinetic equations, to multicellular systems in biology, crowd dynamics, and social sciences and economy viewed as behavioral sciences, occasionally called soft sciences. In more details, the following topics have been tackled: 1) Development of the theory and application of the kinetic theory of the scalled active particles, with the main objective of deriving a general mathematical structure, consistent with the complexity features of living systems, where the dynamics are developed over the space variable. This structure offers the conceptual background for the derivation of specific models corresponding to well-defined classes of systems and substitutes the field theories, which classically offers the natural support in the sciences of the inert matter that cannot be applied in the case of living systems. Applications have also motivated development of simulation tools. 2) Mathematical methods to derive macroscopic tissue equations, of Keller- Segel and Cattaneo type, from the underlying description at the microscopic scale delivered by kinetic type models and development of computational schemes towards simulations both of kinetic transport models and hyperbolic macroscopic models. In more details, finite volume methods for hyperbolic conservative laws equations have been developed for the simulations of macroscopic models. 3) Applications to modeling, qualitative analysis, and simulations of social systems. Applications have been addressed to social systems and behavioral crowd dynamics with a special focus on evacuation dynamics from venues with complex geometry with special focus to a dy- namics, where panic propagates. Simulations have been obtained by a suitable developments of the socalled Monte Carlo particle methods. 4) Analytical problems generated by the convergence of the Hilbert approach to the derivation of macroscopic equations from the kinetic theory approach, and a qualitative analysis related to existence and uniqueness of the solutions of the initial value problems of the kinetic systems.