Financial Fragility and Economic Fluctuations: Numerical Simulations and Policy Implications

This paper proposes a simple prototype model that describes the complex dynamics of a sophisticated monetary economy. The interaction between the current and intertemporal financial constraints of economic units brings about irregular fluctuations at the micro and macro levels. By means of qualitative dynamic analysis and numerical simulations, we reformulate in more operational terms, and extend in a number of new directions, the model suggested recently by one of the authors (Vercelli, 2000) to study the interaction between financial fragility, modelled in terms of structural instability, and dynamically unstable financial fluctuations.Complex dynamics, Structural instability; Financial fragility; Economic fluctuations; Numerical simulations

Patterns of Discovery

From a given directed weighted network of knowledge links between technology fields, the paper develops a multisector dynamic model of incremental innovation and R&D activity in these fields. The model is focused on the equilibrium share distribution of these variables, which is proved to be locally stable, with reference to a simple low dimensional case. Simulation methods suggest that local, and also global, stability extend to any model dimension. It is also shown how different network structures map to different asymptotic share distributions. Using the NBER patents and patent citation data files, the analytical framework is then used to analyse some general features of the pattern of knowledge creation and transfer in the period 1975-1999. From a descriptive viewpoint, the changes in the share distribution of innovation activity predicted by the model match reasonably well the actual changes in the perioddirected weighted network, knowledge spillovers, share distribution, incremental innovation and R&D dynamics, local stability, simulation, patents and patent citations

Metal-Insulator transitions in the periodic Anderson model

We solve the Periodic Anderson model in the Mott-Hubbard regime, using Dynamical Mean Field Theory. Upon electron doping of the Mott insulator, a metal-insulator transition occurs which is qualitatively similar to that of the single band Hubbard model, namely with a divergent effective mass and a first order character at finite temperatures. Surprisingly, upon hole doping, the metal-insulator transition is not first order and does not show a divergent mass. Thus, the transition scenario of the single band Hubbard model is not generic for the Periodic Anderson model, even in the Mott-Hubbard regime.Comment: 5 pages, 4 figure

Genesis and foundations of the multiplier: Marx, Kalecki and Keynes

This paper explores the Marxian genetic root of the multiplier in order to clarify its foundations and validity conditions. Though the analysis is restricted to the first two volumes of Capital and the early contributions by Kalecki in the 1930s, we argue that we can draw from these works valuable insights into the theoretical and empirical scope of the Kahn-Keynes multiplier