How infectious diseases spread in space within one cycle of an epidemic is an important question that has received considerable theoretical attention. There are, however, few empirical studies to support theoretical approaches, because data is scarce. Weekly reports obtained since 1984 from a...

This paper examines the impact of distance-dependent spatial externalities, referred to as "edge-effect externalities," on free-market equilibrium land use patterns. Under edge-effect externalities, maximization of production possibilities will depend on minimization of landscape fragmentation,...

The technique of approximating the mean path of Markov chains by differential equations has proved to be a useful tool in analyzing the performance of heuristics on random graph instances. However, only a small family of algorithms can currently be analyzed by this method, due to the need to...

One of the most popular data sets in ecology, that of lynx fur returns, is analyzed in order to look for evidence for a bifurcation process. This bifurcation seems to be present from the observation of a shift in the amplitude of oscillations of the lynx time series. The possibility for such a...

The emergence of cooperation in Prisoner's Dilemma (PD) games is generally assumed to require repeated play (and strategies such as Tit-For-Tat, involving memory of previous interactions) or features ("tags") permitting cooperators and defectors to distinguish one another. In the Demographic...

While complex adaptive systems (CAS) theories focus primarily on phenomena such as systemic robustness against perturbation, self-organization, and on the emergence, transformation, and dissolution of organizational entities or action patterns, the metaphorical resonance of CAS work is not...

The internalization of norms refers to the tendency of human beings to adopt social norms from parents (vertical transmission) or influential elders (oblique transmission). Authority rather than fitness-enhancing capacity accounts for the adoption of internalized norms. Suppose there is one...

Recently, there has been considerable interest in deriving and applying knowledge-based, empirical potential functions for proteins. These empirical potentials have been derived from the statistics of interacting, spatially neighboring residues, as may be obtained from databases of known protein...

We study the stochastic folding kinetics of RNA sequences into secondary structures with a new algorithm based on the formation, dissociation, and the shifting of individual base pairs. We discuss folding mechanisms and the correlation between the barrier structure of the conformational...

The concept of a "fitness landscape," a picturesque term for a mapping of the vertices of a finite graph to the real numbers, has arisen in several fields, including evolutionary theory. The computational complexity of two, qualitatively similar versions of a particularly simple fitness...