Learn More
The study of animal foraging behaviour is of practical ecological importance, and exemplifies the wider scientific problem of optimizing search strategies. Lévy flights are random walks, the step lengths of which come from probability distributions with heavy power-law tails, such that clusters of short steps are connected by rare long steps. Lévy flights(More)
The study of the robust features of the magnetosphere is motivated both by new " whole system " approaches, and by the idea of " space climate " as opposed to " space weather ". We enumerate these features for the AE index, and discuss whether self-organised criticality (SOC) is the most natural explanation of the " stylised facts " so far known for AE. We(More)
We calculate for the first time the probability density functions (PDFs) P of burst energy e, duration T and inter-burst interval τ for a known turbulent system in nature. Bursts in the earth-sun component of the Poynting flux at 1 AU in the solar wind were measured using the MFI and SWE experiments on the NASA WIND spacecraft. We find P (e) and P (T) to be(More)
There is substantial interest in the effect of human mobility patterns on opportunistic communications. Inspired by recent work revisiting some of the early evidence for a L´evy flight foraging strategy in animals, we analyse datasets on human contact from real world traces. By analysing the distribution of inter-contact times on different time scales(More)
Although metaphorical and conceptual connections between the human brain and the financial markets have often been drawn, rigorous physical or mathematical underpinnings of this analogy remain largely unexplored. Here, we apply a statistical and graph theoretic approach to the study of two datasets - the time series of 90 stocks from the New York stock(More)
Long-range dependence (LRD) and non-Gaussianity are ubiquitous in many natural systems such as ecosystems, biological systems and climate. However, it is not always appreciated that the two phenomena may occur together in natural systems and that self-similarity in a system can be a superposition of both phenomena. These features, which are common in(More)
Mandelbrot introduced the concept of fractals to describe the non-Euclidean shape of many aspects of the natural world. In the time series context he proposed the use of fractional Brownian motion (fBm) to model non-negligible temporal persistence, the " Joseph Effect " ; and Lévy flights to quantify large dis-continuities, the " Noah Effect ". In space(More)
The characterization of global energy storage and release in the coupled solar wind-magnetosphere system remains one of the fundamental problems of space physics. Recently, it has been realised that a new paradigm in physics, that of Self Organised Criticality (SOC) may encapsulate the mixing and merging of flux on many scales in the magnetotail prompting(More)