Nonlinearities, disequilibria and simulation : proceedings of the Arne Ryde Symposium on Quantitative Methods in the Stabilization of Macrodynamic Systems : essays in honour of Björn Thalberg / Kumaraswamy Velupillai, ThalbergBjörn, ArneRydeSymposiumonQuantitativeMethodsintheStabilizationofMacrodynamicSystems