Dynamic behavior of domain walls in double layer self-biasing bubble garnet films

Radial expansion of bubbles and gradient bubble propagation experiments were conducted in a double layer garnet film with perpendicular anisotropy in both layers. Implanted and as-grown samples are compared. In radial expansion the side walls of the bubble exhibit a linear mobility much lower than calculated from γΔ/α. Saturation occurs at high drives (35 Oe). At drives above 50 Oe the saturation velocity of 27 m/s occurs only in the first 120 ns of the motion. After that the velocity drops to 17.5 m/s still independent of drive. This break in velocity does not occur in implanted samples, where the saturation velocity depends on implantation conditions. In gradient propagation saturation occurs at fields an order of magnitude smaller. The saturation velocity is independent of implantation, but overshoot depends strongly on it. No creep was detected. The 180° head-on domain wall between the two layers is found to have little effect on the dynamics of the side walls of the bubble. The motion of the head-on wall is also investigated and its velocity estimated. This head-on wall exhibits a linear mobility and a saturation velocity at high drives

Entropies, Partitionings and Heart Rate Variability

. Several definitions of static entropies and coarse-grained entropy rates CER's were used to analyze 24-hour RR interval sequences of three sex, age and disease matched control pairs. The matching was done with the assessment of the risk of cardiac arrest in mind. Details of estimating probability densities (histograms), used to compute the static entropies, have been found crucial to obtain the proper discrimination between the members of control pairs. The effect of signal variance on the entropy estimation is discussed. In a preliminary result, CER's have been found to yield additional information which may be helpful in discriminating health and pathology. 1 Introduction This study was inspired by the basic question, which is often asked by all time-series analysts dealing with physiological data, namely, which property of the data discriminates health from pathology and how this property can be described and measured, so that a reliable diagnostic tool is obtained. The data inve..

Kolmogorov Complexity of Coronary Sinus Atrial Electrograms Before Ablation Predicts Termination of Atrial Fibrillation After Pulmonary Vein Isolation

Atrial fibrillation (AF) is related to a very complex local electrical activity reflected in the rich morphology of intracardiac electrograms. The link between electrogram complexity and efficacy of the catheter ablation is unclear. We test the hypothesis that the Kolmogorov complexity of a single atrial bipolar electrogram recorded during AF within the coronary sinus (CS) at the beginning of the catheter ablation may predict AF termination directly after pulmonary vein isolation (PVI). The study population consisted of 26 patients for whom 30 s baseline electrograms were recorded. In all cases PVI was performed. If AF persisted after PVI, ablation was extended beyond PVs. Kolmogorov complexity estimated by Lempel–Ziv complexity and the block decomposition method was calculated and compared with other measures: Shannon entropy, AF cycle length, dominant frequency, regularity, organization index, electrogram fractionation, sample entropy and wave morphology similarity index. A 5 s window length was chosen as optimal in calculations. There was a significant difference in Kolmogorov complexity between patients with AF termination directly after PVI compared to patients undergoing additional ablation (p < 0.01). No such difference was seen for remaining complexity parameters. Kolmogorov complexity of CS electrograms measured at baseline before PVI can predict self-termination of AF directly after PVI

Nonlinear Analysis of the Cardiorespiratory Coordination in a Newborn Piglet

. We investigate the cardiorespiratory system of a newborn piglet during REM and NON--REM sleep as well as general anesthesia, hypoxia, and cholinergic blockade. The coordinated behavior of heart rate fluctuation and respiratory movement reflects essential capabilities of the autonomic coordination. A corresponding multivariate data analysis was done by means of several nonlinear methods: generalized mutual information, redundancy and surrogate data, window pattern entropy, and computation of phase relations. Some of them are applied for the first time in this context. 1 Introduction The stable operation of organisms is based on the complex coordination between several physiological subsystems. In the present paper we use different nonlinear techniques of multivariate time series analysis to address corresponding interactions within the autonomic nervous system (ANS). Relevant nonlinear properties of the heart rate dynamics are confirmed which may improve concepts of medical treatment..

Overview of the COMPASS results

COMPASS addressed several physical processes that may explain the behaviour of important phenomena. This paper presents results related to the main fields of COMPASS research obtained in the recent two years, including studies of turbulence, L–H transition, plasma material interaction, runaway electron, and disruption physics: • Tomographic reconstruction of the edge/SOL turbulence observed by a fast visible camera allowed to visualize turbulent structures without perturbing the plasma. • Dependence of the power threshold on the X-point height was studied and related role of radial electric field in the edge/SOL plasma was identified. • The effect of high-field-side error fields on the L–H transition was investigated in order to assess the influence of the central solenoid misalignment and the possibility to compensate these error fields by low-field-side coils. • Results of fast measurements of electron temperature during ELMs show the ELM peak values at the divertor are around 80% of the initial temperature at the pedestal. • Liquid metals were used for the first time as plasma facing material in ELMy H-mode in the tokamak divertor. Good power handling capability was observed for heat fluxes up to 12 MW m−2 and no direct droplet ejection was observed. • Partial detachment regime was achieved by impurity seeding in the divertor. The evolution of the heat flux footprint at the outer target was studied. • Runaway electrons were studied using new unique systems—impact calorimetry, carbon pellet injection technique, wide variety of magnetic perturbations. Radial feedback control was imposed on the beam. • Forces during plasma disruptions were monitored by a number of new diagnostics for vacuum vessel (VV) motion in order to contribute to the scaling laws of sideways disruption forces for ITER. • Current flows towards the divertor tiles, incl. possible short-circuiting through PFCs, were investigated during the VDE experiments. The results support ATEC model and improve understanding of disruption loads