Leviathan and pure public goods in a federation with mobile populations

This paper investigates properties of the second best allocation in a federation where regional governments provide a pure public good non-cooperatively and policy makers are neither entirely benevolent nor wholly self-serving. A high degree of household mobility across regions forces the governments to raise the efficiency of the public good, however, it also helps to waste resources. It is shown that regional Leviathans not only under-provide the public good but also decrease the amount of wasteful expenditures as households become less mobile. Central government’s intervention can enhance efficiency if households are attached to particular regions.Pure public goods, Leviathan, household mobility

Theory of Robustness of Irreversible Differentiation in a Stem Cell System: Chaos hypothesis

Based on extensive study of a dynamical systems model of the development of a cell society, a novel theory for stem cell differentiation and its regulation is proposed as the ``chaos hypothesis''. Two fundamental features of stem cell systems - stochastic differentiation of stem cells and the robustness of a system due to regulation of this differentiation - are found to be general properties of a system of interacting cells exhibiting chaotic intra-cellular reaction dynamics and cell division, whose presence does not depend on the detail of the model. It is found that stem cells differentiate into other cell types stochastically due to a dynamical instability caused by cell-cell interactions, in a manner described by the Isologous Diversification theory. This developmental process is shown to be stable not only with respect to molecular fluctuations but also with respect to removal of cells. With this developmental process, the irreversible loss of multipotency accompanying the change from a stem cell to a differentiated cell is shown to be characterized by a decrease in the chemical diversity in the cell and of the complexity of the cellular dynamics. The relationship between the division speed and this loss of multipotency is also discussed. Using our model, some predictions that can be tested experimentally are made for a stem cell system.Comment: 31 pages, 10 figures, submitted to Jour. Theor. Bio