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In this paper, we consider the shape instability of ferroelectric wavy domain wall that moves uniformly in the ferroelectric capacitor under the constant uniform electric field. The retardation of the bulk screening of residual depolarization field and existing of the surface dielectric layers were taken into account. It was shown that the spatial distribution of the electric field in the ferroelectric plate led to topological instability of the moving wavy domain wall. The obtained results are important for the formation of the self-assembled domain structures in ferroelectrics. [ABSTRACT FROM AUTHOR]

In this paper, we established the origin of the experimentally observed topological instability representing the change of the plane domain wall shape by formation of so-called “fingers” during fast polarization reversal of the ferroelectric capacitor. By means of a simplified model we show that the topological instability of the domain wall can be attributed to retardation of the bulk screening of residual depolarization field. [ABSTRACT FROM PUBLISHER]

Technical problems accompanying the recording of fiber pair potentials introduce certain instability in the peak-to-peak interval (rise-time, RT) of these potentials. This study aims (1) to measure the variability observed in RT of a large number of sets of consecutive potentials recorded by a single-fiber (SF) electrode and (2) to evaluate the effect of such variability on the jitter estimation. Using a SF electrode, 140 sets of consecutive potentials were recorded from the m. tibialis anterior of four healthy subjects. For each set, the rise-time variability (RTV) was calculated as the standard deviation of the RTs of the discharges within that set. The effect of RTV in the estimation of jitter from simulated fiber pairs with controlled values of neuromuscular jitter was analyzed. The RTVs of sets visually assessed as produced by a 'single-fiber' were always less than 20 μs, whereas those of 'composite' sets were normally higher than 20 μs. We found that the RTV always increased the estimated jitter of fiber pairs. Such increment depended on the amount of neuromuscular jitter. The RTV provides an estimate of the possible error introduced in jitter assessment. This could be important for the diagnosis of mild clinical manifestations of myasthenia gravis, myopathies, and Duchenne dystrophies. [ABSTRACT FROM AUTHOR]

A theoretical analysis was made of the relaxed plain-knitted structure. The analysis differs from previous ones in that no arbitrary geometrical loop shape is assumed and no empirical methods are used. The loop configuration is de rived from consideration of the reaction forces and couples acting within the structure, their magnitude being determined by the yarn displacement necessary for loop interlocking. A minimum-energy structure is shown to exist; this structure is fairly independent of fabric tightness and yarn properties. The actual energy minimum is fairly shallow, so that in practice some difficulty could be expected in obtaining a perfectly relaxed fabric; this would lead to a corresponding spread in experimental values of plain-knitted fabric shape and dimensions. The numerical values of fabric dimensions obtained from the analysis show good agreement with the experimental data reported by other workers. [ABSTRACT FROM PUBLISHER]