Neil F. Johnson

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An evolving population, in which individual members (‘agents’) adapt their behaviour according to past experience, is of central importance to many disciplines. Because of their limited knowledge and capabilities, agents are forced to make decisions based on inductive, rather than deductive, thinking. We show that a population of competing agents with(More)
Quantifying human group dynamics represents a unique challenge. Unlike animals and other biological systems, humans form groups in both real (offline) and virtual (online) spaces-from potentially dangerous street gangs populated mostly by disaffected male youths to the massive global guilds in online role-playing games for which membership currently exceeds(More)
In a system containing a large number of interacting stochastic processes, there will typically be many nonzero correlation coefficients. This makes it difficult to either visualize the system's interdependencies, or identify its dominant elements. Such a situation arises in foreign exchange (FX), which is the world's biggest market. Here we develop a(More)
Children with congenital and acquired heart disease typically undergo imaging procedures that may expose them to large amounts of ionizing radiation. Radiation exposure in childhood is of particular concern because children have immature developing organ and tissue structures. These factors, as well as the potentially longer lifespan of these children, may(More)
Many collective human activities, including violence, have been shown to exhibit universal patterns. The size distributions of casualties both in whole wars from 1816 to 1980 and terrorist attacks have separately been shown to follow approximate power-law distributions. However, the possibility of universal patterns ranging across wars in the size(More)
S ignificant and interrelated atmospheric, oceanic, and terrestrial changes have been occurring in the Arctic in recent decades (SEARCH SSC 2001; ACIA 2005). These changes are broad ranging, impacting every part of the Arctic environment. The Arctic is observed to be warming at a rate approximately twice that of the global average (ACIA 2005). Indeed,(More)
We study the cluster dynamics of multichannel (multivariate) time series by representing their correlations as time-dependent networks and investigating the evolution of network communities. We employ a node-centric approach that allows us to track the effects of the community evolution on the functional roles of individual nodes without having to track(More)
The dynamical evolution of many economic, sociological, biological, and physical systems tends to be dominated by a relatively small number of unexpected, large changes ("extreme events"). We study the large, internal changes produced in a generic multiagent population competing for a limited resource, and find that the level of predictability increases(More)
We report on a technique based on multi-agent games which has potential use in the prediction of future movements of financial time-series. A third-party game is trained on a black-box time-series, and is then run into the future to extract nextstep and multi-step predictions. In addition to the possibility of identifying profit opportunities, the technique(More)
We show how optically-driven coupled quantum dots can be used to prepare maximally entangled Bell and Greenberger-Horne-Zeilinger states. Manipulation of the strength and duration of the selective light-pulses needed for producing these highly entangled states provides us with crucial elements for the processing of solid-state based quantum information.(More)