Santa Fe Institute

About: Santa Fe Institute is a nonprofit organization based out in Santa Fe, New Mexico, United States. It is known for research contribution in the topics: Population & Complex network. The organization has 558 authors who have published 4558 publications receiving 396015 citations. The organization is also known as: SFI.

Analysis of RNA sequence structure maps by exhaustive enumeration I. Neutral networks

Abstract: Global relations between RNA sequences and secondary structures are understood as mappings from sequence space into shape space. These mappings are investigated by exhaustive folding of allGC andAU sequences with chain lengths up to 30. The computed structural data are evaluated through exhaustive enumeration and used as an exact reference for testing analytical results derived from mathematical models and sampling based on statistical methods. Several new concepts of RNA sequence to secondary structure mappings are investigated, among them that ofneutral networks (being sets of sequences folding into the same structure). Exhaustive enumeration allows to test several previously suggested relations: the number of (minimum free energy) secondary structures as a function of the chain length as well as the frequency distribution of structures at constant chain length (commonly resulting in generalized forms ofZipf's law).

The Complexity of Exchange

Abstract: The computational complexity of two classes of market mechanisms is compared. First the Walrasian interpretation in which prices are centrally computed by an auctioneer. Recent results on the computational complexity are reviewed. The non-polynomial complexity of these algorithms makes Walrasian general equilibrium an implausible conception. Second, a decentralised picture of market processes is described, involving concurrent exchange within transient coalitions of agents. These processes feature price dispersion, yield allocations that are not in the core, modify the distribution of wealth, are always stable, but path-dependent. Replacing the Walrasian framing of markets requires substantial revision of conventional wisdom concerning markets.

Quantitative historical analysis uncovers a single dimension of complexity that structures global variation in human social organization.

Abstract: Do human societies from around the world exhibit similarities in the way that they are structured, and show commonalities in the ways that they have evolved? These are long-standing questions that have proven difficult to answer. To test between competing hypotheses, we constructed a massive repository of historical and archaeological information known as “Seshat: Global History Databank.” We systematically coded data on 414 societies from 30 regions around the world spanning the last 10,000 years. We were able to capture information on 51 variables reflecting nine characteristics of human societies, such as social scale, economy, features of governance, and information systems. Our analyses revealed that these different characteristics show strong relationships with each other and that a single principal component captures around three-quarters of the observed variation. Furthermore, we found that different characteristics of social complexity are highly predictable across different world regions. These results suggest that key aspects of social organization are functionally related and do indeed coevolve in predictable ways. Our findings highlight the power of the sciences and humanities working together to rigorously test hypotheses about general rules that may have shaped human history.

A Sound Rationale Needed for Phase III HIV-1 Vaccine Trials

Abstract: Concerns are expressed by a group of AIDS researchers about the U.S. government9s plans to conduct a phase III trial of a combination HIV-1 vaccine in Thailand despite the cancellation of a trial of a very similar combination vaccine in the U.S.A. last year. One of the vaccine components, recombinant monomeric gp120, has already been shown to be ineffective in phase III trials in Thailand and the United States; the other component, a recombinant canarypox vector, is also poorly immunogenic. The scientific rationale that has been offered for the new trial in Thailand is considered by the authors to be weak.

History, Expectations, and Leadership in the Evolution of Social Norms

Abstract: We study the evolution of the social norm of "cooperation" in a dynamic environment. Each agent lives for two periods and interacts with agents from the previous and next generations via a coordination game. Social norms emerge as patterns of behavior that are stable in part due to agents' interpretations of private information about the past, which are influenced by occasional past behaviors that are commonly observed. We first characterize the (extreme) cases under which history completely drives equilibrium play, leading to a social norm of high or low cooperation. In intermediate cases, the impact of history is potentially countered by occasional "prominent" agents, whose actions are visible by all future agents, and who can leverage their greater visibility to influence expectations of future agents and overturn social norms of low cooperation. We also show that in equilibria not completely driven by history, there is a pattern of "reversion" whereby play starting with high (low) cooperation reverts toward lower (higher) cooperation.