Leo Moseley

A Predator–Prey Model with Genetics: Transition to a Self-Organized Critical State

A two species predator–prey model based on the Lotka–Volterra equations is proposed, where the fitness of an individual animal depends upon the relative strength of its genes. Simulations of the model show that the system passes from the standard oscillatory solution of the Lotka–Volterra equations into a steady-state regime, which exhibits many of the characteristics of self-organized criticality, including a 1/f power spectrum.

Is the fossil record indicative of a critical system

We examine the distribution of the relative fractional fluctuation of the magnetisation of a 3D Ising ferromagnet at the critical temperature Tc by considering a histogram of frequency of the fractional magnetisation. The distribution is highly non-Gaussian and is reminiscent of the histogram of extinction intensity for fossil genera shown by Raup1 (1991) (see also Newman (1996)). The graph of relative fractional change ofmagnetisation vs MC time is compatible in appearance with the graph showing the variation of the number of extinction of families of marine animals with time (over hundreds of millions of years) given by Raup (1991), Sepkoski (1993) or Newman (1996). Our results show a power law dependence usually taken as evidence for the existence of a critical system.

A Hypothesis for the Evolution of Sex

Sex is one of the most creative of the major transitions in Evolution and its existence allows faster and wider mobility of species in the ‘History of Life’. We postulate that sex evolved from prokaryotes in the tail of the fitness distribution curve for a given environment. Once sex was established we have the potential for the evolution of species and the rich flowering of organisms in a relatively short period of time.

SPECIATION FROM EVOLUTION

Evolution, based on the principles of mutation and selection, is a powerful basis for microscopic changes which can account for the evolution of a species and macroscopic speciation where there is splitting of a species into two distinct new species. We show that a single species evolves into distinct species after several generations in an unrestricted genome space.

The potential of PV installations in SIDS – an example in the island of Barbados

Purpose – This paper reviews the current status of photovoltaics on the island of Barbados, including experiences to date, and discusses the future directions with a view to sharing the experience gained with other small island developing states (SIDS).Design/methodology/approach – As with many SIDS Barbados is heavily reliant on fossil fuels to meet their electricity generation needs (currently 98 per cent of total electricity generation). The paper outlines how solar PV sits within the existing energy structure for the island of Barbados and reflects on the experience gained from the success of its solar thermal hot water heating industry.Findings – This paper estimates the installed capacity of photovoltaic solar systems on Barbados was estimated to be around 200 kWp in 2010 (0.18 per cent of the average electricity demand, not including the load factor of the PV systems).Practical implications – With an average daily solar radiation of 5.7 kWh/m2, the potential of the resource is clear to see, with so...

Caribbean RE: policies, competition and regulations

Purpose – A growing body of research has identified many barriers (such as education, identification of appropriate technologies, research and development in the indigenous environments and, perhaps most importantly, public policy) to the implementation of renewable energy (RE) programmes in small island developing states (SIDS). This paper seeks to examine the proposition that lack of an integrated RE policy, necessary non‐technical infrastructure and insufficient investment continues to limit the development and commercialization of RE technologies.Design/methodology/approach – The study surveyed literature, focusing on policies for supporting RE and the issues of competition and regulation. Caribbean policies for supporting RE were compared with those in selected countries.Findings – The findings indicate that while undertaking a series of policy, economic, market and research and development (R&D) measures will advance the RE technologies and their deployment, it is also the case that regulatory manda...

Self-organised criticality in a genetic model of species-species interaction

Genetics incorporated into a two trophic level species-species interaction model allows the populations of species to evolve. The system enters a regime where the extinction of species follows an erratic pattern in time and appears chaotic to the eye. Quantitative measurements suggest that the dynamics of the model exhibits self organised criticality. Fourier Transform analysis of the time series and autocorrelation function for the population data, as well as the distribution of lineage sizes and longevity of lineages, all show power law behavior. The lineages are the analogue of avalanches in other models of self organised criticality

Nonequilibrium dynamics of a diffusion-limited reaction driven by a cluster-memory mechanism

The diffusion-limited reaction A+A↔A+B is studied in general dimension. The asymptotic decay of the system is found to depend nontrivially upon the initial concentration of A particles for certain ranges of the diffusion constant, backward reaction rate, and total concentration of particles. This nonequilibrium behavior is due to the formation of clusters centered about the initial A particles. A perturbative analysis ind=1 shows that the transition to the nonequilibrium dynamics is sharp and is quite similar to another previously studied reaction A+A↔A. Ford>1, a scaling argument is presented which describes the dependence of the asymptotic decay on the initial concentration of A particles and the equilibrium concentration for large backward reaction rates. Monte Carlo data are shown which confirm the analytic work ind=1, 2, and 3.

Kawasaki dynamics with infinite-range spin exchange

The essential feature of the Kawasaki model is the conserved order parameter, which places the model in class B of the Halperin, Hoheberg, and Ma classification. We have studied the energy relaxation of this model in one and two dimensions with the added feature that spin exchange may take place between any pair of sites within the system. Our results for the dynamic exponentz are indistinguishable from those for class A models, in which the order parameter is not conserved.

Originations And Extinctions: Analyses Of Fossil Data And Simulations

We analyse the fossil data of Benton1 with and without interpolation schemes. By Fourier transform analysis, we find a frequency dependence of the amplitude of 1/f for the various interpolation schemes used in the past. We illustrate that shuffling the interpolated data changes the spectra only slightly. On the other hand, an identical analysis performed on the raw (uninterpolated) fossil data gives a flat frequency spectrum. We conclude that the 1/f behavior is an artifact of the interpolation schemes. We next introduce a simulation of extinctions driven only by interactions between two trophic levels. Fourier transform analysis of the simulation data shows a frequency dependence of 1/f. When the data are grouped into a form resembling the fossil record the frequency dependence vanishes, giving a flat spectrum. Our simulation produces a frequency spectrum that agrees with the observed fossil record.