Timely detection of unusual and/or unexpected events in natural and man-made systems has deep scientific and practical relevance. We show that the recently proposed conceptually simple and easily calculated measure of permutation entropy can be effectively used to detect qualitative and quantitative dynamical changes. We illustrate our results on two model systems as well as on clinically characterized brain wave data from epileptic patients.

Amnestic mild cognitive impairment (aMCI) often is an early stage of Alzheimer’s disease (AD). MCI is characterized by cognitive decline departing from normal cognitive aging but that does not significantly interfere with daily activities. This study explores the potential of scalp EEG for early detection of alterations from cognitively normal status of older adults signifying MCI and AD. Resting 32-channel EEG records from 48 age-matched participants (mean age 75.7 years)–15 normal controls (NC), 16 early MCI, and 17 early stage AD–are examined. Regional spectral and complexity features are computed and used in a support vector machine model to discriminate between groups. Analyses based on three-way classifications demonstrate discrimination accuracies of 83.9%–96.8% for MCI vs. NC (p-value<0.0029), 71.9%–96.9% for AD vs. NC (p-value<0.0333), and 87.9%–90.9% for AD vs. MCI (pvalue<0.0136), depending on the EEG protocol condition employed. These results demonstrate the great promise for scalp EEG spectral and complexity features as noninvasive biomarkers for detection of MCI and early AD.

A method of calculating the wall loading due to fusion products escaping from the plasma in a tokamak is described. For this purpose, the small-banana-width approximation is eliminated, yielding an analytic formulation for high-energy orbits and associated loss-cone limits. Wall-loading profiles (as a function of poloidal angle) are presented for various experimental devices (PLT, TFTR, and ORNL-EPR) and for a typical reactor (UWMAK-I). Peak-to-average alpha flux ratios of the order of 1.4 to 2.3 combined with average fluxes of ∼ 1011 alphas per cm2 per second, suggest that localized blistering may be a serious source of impurity atoms as well as a wall erosion mechanism. Special wall panels in regions of high flux are suggested. Other implications include a unique suggestion for fuel injection along special orbits intercepted via a bundle divertor.