Cross-reactive memory responses occur when the immune system is primed by one strain of a pathogen and challenged with a related, but different strain. Much of the nature of a cross-reactive response is determined by the quantity and distribution of the memory cells, raised to the primary...

We provide an overview of recent empirical research on patterns of cross-country growth. The new empirical regularities considered differ from earlier ones, e.g., the well-known Kaldor stylized facts. The new research no longer makes production function accounting a central part of the analysis....

A number of recent attempts to understand broad principles of energy transduction in biological systems have focused on correlation ratchets---systems which extract work out of fluctuations which are correlated in time. Correlation ratchets are "information engines" analogous to Maxwell's...

The allocation of discrete, complementary resources is a fundamental problem in economics and of direct interest to e-commerce applications. In this paper we establish that competitive equilibrium bundle prices always exist that support the efficient allocation in discrete resource allocation...

We present a model of opinion dynamics in which agents adjust continuous opinions as a result of random binary encoun ters whenever their difference in opinion is below a given threshold. High thresholds yield convergence of opinions towards an average opinion, whereas low thresholds result in...

We provide a survey of methods for inferring the structure of a finite automaton from passive observation of its behavior. We consider both deterministic automata and probabilistic automata (similar to Hidden Markov Models). While it is computationally intractible to solve the general problem...

Social insects provide us with a powerful metaphor to create decentralized systems of simple interacting, and often mobile, agents. The emergent collective intelligence of social insects---swarm intelligence---resides not in complex individual abilities but rather in networks of interactions...

While questions about social cohesion lie at the core of our discipline, no clear definition of cohesion exists. We present a definition of structural cohesion based on network connectivity that leads to an operationalization of a dimension of social embeddedness. Structural cohesion is defined...

This working paper reports the main lines of discussion that developed during a four-day workshop held August 10-13, 1995, at the Santa Fe Institute, Santa Fe, New Mexico. The workshop was devoted to exploring the difficulties and promise of current research on organizational routines and...

We introduce a method for visualizing evolutionary activity of genotypes. Following a proposal of Bedau and Packard[11], we define a genotype's evolutionary activity in terms of the history of its concentration in the evolving population. To visualize this evolutionary activity we graph the...