Aging in coherent noise models and natural time

Event correlation between aftershocks in the coherent noise model is studied by making use of natural time, which has recently been introduced in complex time-series analysis. It is found that the aging phenomenon and the associated scaling property discovered in the observed seismic data are well reproduced by the model. It is also found that the scaling function is given by the $q$-exponential function appearing in nonextensive statistical mechanics, showing power-law decay of event correlation in natural time.Comment: 4 pages and 5 figure

P2X7 purinoceptor expression in Xenopus oocytes is not sufficient to produce a pore-forming P2Z-like phenotype

AbstractThe purinergic rP2X7 receptor expressed in a number of heterologous systems not only functions as a cation channel but also gives rise to a P2Z-like response, i.e. a reversible membrane permeabilization that allows the passage of molecules with molecular masses of ≥300 Da. We investigated the properties of rP2X7 receptors expressed in Xenopus oocytes. In two-electrode voltage-clamp experiments, ATP or BzATP caused inward currents that were abolished or greatly diminished when NMDG+ or choline+ replaced Na+ as the principal external cation. In fluorescent dye experiments, BzATP application did not result in entry of the fluorophore YO-PRO-12+. Thus, rP2X7 expression in Xenopus oocytes does not by itself give rise to the pore-forming P2Z phenotype, suggesting that ancillary factors are involved

Creative Potential in Science: Conceptual and Measurement Issues

This paper examines the concept of creative potential as it applies in science. First, conceptual issues concerning the definition of creative potential are explored, highlighting that creative potential is a moving target, and measures of creative potential are estimates of future behavior. Then three main ways to detect creative potential are examined. First, a person's previous accomplishments in science can be analyzed. These accomplishments can be regarded as predictors of future creative performance. Second, science talent competitions can help to detect creative potential in children and adolescents. There are particular types of talent competitions differing from each other by the extent of focusing on individual (e.g., Science Fairs) or collaborative (e.g., Science Olympiads) work. Third, to measure an individual's creative potential, psychometric tools such as Creative Scientific Ability Test (C-SAT), Test of Scientific Creativity Animations for Children (TOSCAC), and Evaluation of Potential Creativity (EPoC) can be used. These tools are conceptualized in terms of two scientific activities: hypothesis generation and hypothesis testing. In a final section, these three types of measures are placed in a novel time-space framework as applied to creative potential. Suggestions for future work are also discussed

Two-dimensional maps at the edge of chaos: Numerical results for the Henon map

The mixing properties (or sensitivity to initial conditions) of two-dimensional Henon map have been explored numerically at the edge of chaos. Three independent methods, which have been developed and used so far for the one-dimensional maps, have been used to accomplish this task. These methods are (i)measure of the divergence of initially nearby orbits, (ii)analysis of the multifractal spectrum and (iii)computation of nonextensive entropy increase rates. The obtained results strongly agree with those of the one-dimensional cases and constitute the first verification of this scenario in two-dimensional maps. This obviously makes the idea of weak chaos even more robust.Comment: 4 pages, 3 figure