Signaling networks are exemplified by systems as diverse as biological cells, economic markets, and the Web. After a discussion of some general characteristics of signaling networks, this paper explores the adaptive evolution of complexity in a simple model of a signaling network. The paper...

In this paper we prove a Faber-Krahn-type inequality for regular trees and give a complete characterization of extremal trees. The main tools are rearrangements and perturbation of regular trees.

We show closed-form analytic functions consisting of a finite number of trigonometric terms can simulate Turing machines, with exponential slowdown in one dimension or in real time in two or more. <p> Key words. dynamical systems, universal computation, iterated maps, analytic functions, Halting...</p>

RNA viruses are known to replicate with extremely high mutation rates. These rates are actually close to the so-called error threshold. This threshold is in fact a critical point beyond which genetic information is lost through a second-order phase transition, which has been dubbed the ``error...

We present and analyze a model for the cross-regulation of the Th1 and Th2 helper cell subsets during an immune response by the regulatory cytokines interferon-$\gamma$ (IFN-$\gamma$) and interleukin-10 (IL-10). IFN-$\gamma$, secreted by Th1 cells, can inhibit the proliferation of Th2 cells....

I consider the research university from a complex adaptive systems perspective, and offer some modest proposals for the university of the future-a student-based complex adaptive learning community in which both feedback and transdisciplinary problem-oriented Centers play central roles. <p> <p> To...</p></p>

In recent studies, new measures of complexity for nonlinear systems have been proposed based on probabilistic grounds, as the LMC measure (Phys. Lett. A 209 (1995) 321). All these measures share an intuitive consideration: complexity seems to emerge in nature close to instability points, as for...

This paper introduces a simple two-dimensional map exhibiting several generic properties reported in excitable systems. The elementary dynamic that is analogous to that of neural elements, is analyzed using phase-plane methods. Bifurcations from non-autonomous to autonomous, and from periodic to...

In this paper we build a spatial, aspiration-based model of learning in the context of Cournot oligopoly from which we want to explore the conditions that lead to the emergence of cooperation among firms. We consider an economy consisting of many identical duopolies; each duopoly is placed on a...

The paper discusses the role of self-organizing phenomena like emergence of infrastructure and self-organizing criticality in a spatial economy. Some theoretical models are discussed and reviewed. Computer models in the form of simple cellular automata, similar to the game "Life" and Schelling's...