Strong reciprocity refers to the willingness to sacrifice one's own material self-interest to punish others for opportunistic actions. This propensity provides a decentralized mechanism for the enforcement of social norms, but its extent and persistence poses a theoretical puzzle. Since...

A key notion in the study of network dynamics is that state-space is connected into basins of attraction. Convergence in attractor basins correlates with order-complexity-chaos measures on space-time patterns. A network's "memory," its ability to categorize, is provided by the configuration of...

Connectivity is a measure of the number of connections in a network. It is applied here to financial network shutdown due to inter-institutional default. Since 1797 when Sir Francis Baring introduced the concept of ``lender of last resort" concepts such as "too-big-to fail",...

Populations may be regulated by both local density-dependent factors and spatial variation in habitat quality. I explore the influence of spatial autocorrelation in habitat quality on the survival of model populations. Dispersal is modeled as Markov transitions between patches. A finite rate of...

We introduce and analyze a general model of a population evolving over a network of selectively neutral genotypes. We show that the population's limit distribution on the neutral network is solely determined by the network topology and given by the principal eigenvector of the network's...

The general theme of temporal asymmetries in clade histories has often been studied with particular attention to the lower Paleozoic radiations. Post-Paleozoic patterns, however, are less well understood. In this paper, disparity and diversity changes in Mesozoic heart urchins were analyzed in...

We use a very simple description of human driving behavior to simulate traffic. The regime of maximum vehicle flow in a closed system shows near-critical behavior, and as a result a sharp decrease of the predictability of travel time. Since Advanced Traffic Management Systems (ATMSs) tend to...

Control rules governing activity of eukaryotic genes appear strongly biased toward large numbers of "canalizing" inputs. The ensemble of networks with the observed bias predicts cells are in an ordered regime with convergent flow in transcription state space, a percolating subnetwork of genes...

We study the four-state antiferromagnetic Potts model on the triangular lattice. We show that the model has six types of defects which diffuse and annihilate according to certain conservation laws consistent with their having a vector-valued topological charge. Using the properties of these...

We extend an earlier model of protein evolution on a rugged landscape (Macken, C.A. & Perelson, A.S., {\it Proc. Natl. Acad. Sci. USA} {\bf 86,} 6191 (1989)) to the case in which the landscape exhibits a variable degree of correlation (i.e., smoothness). Correlation is introduced by assuming...