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This study contrasted the stochastic force component between young and older adults, who performed pursuit tracking/compensatory tracking by exerting in-phase/antiphase forces to match a sinusoidal target. Tracking force was decomposed into the force component containing the target frequency and the nontarget force fluctuations (stochastic component). Older adults with inferior task performance had higher complexity (entropy across time; p =.005) in total force. For older adults, task errors were negatively correlated with force fluctuation complexity (pursuit tracking: r = −.527 to −.551; compensatory tracking: r = −.626 to −.750). Notwithstanding an age-related increase in total force complexity (p =.004), older adults exhibited lower complexity of the stochastic force component than young adults did (low frequency: p =.017; high frequency: p =.035). Those older adults with a higher complexity of stochastic force had better task performance due to the underlying use of a richer gradation strategy to compensate for impaired oscillatory control. [ABSTRACT FROM AUTHOR]

A postural tremor appears whenever someone attempts to maintain a steady position against gravity. We examined the postural tremor that occurred while air pistol shooters were taking aim so as to compare the coordinative control of the shooters and to identify the features critical to successful shooting. Ten elite and ten pre-elite athletes participated in pistol shooting at 10 m, and the postural tremors in the pistol and upper limb were recorded with lightweight accelerometers. Exploratory analysis showed that the elite shooters had smaller tremor amplitudes than the pre-elite shooters in the pistol and distal arm segments. Compared with the pre-elite shooters, the elite shooters had a smaller tremor amplitude in the lateral direction relative to that in the vertical direction, together with weaker tremor coupling in the lateral direction and stronger vertical coupling of the pistol-hand complex. The resulting shot performance was inversely related to the amplitude of the tremor and to the 8-12 Hz spectral peak of the lateral tremor in the pistol-hand complex. We conclude that the postural tremors of air pistol shooters are associated with the skill of the shooters, and that the elite shooters could optimize the control of the pistol-hand complex, which strongly determined success in shooting. [ABSTRACT FROM AUTHOR]

To balance the cost and volume when applying a low output current ripple, the power supply design should be able to eliminate the current ripple under any duty cycle in medium and high switching frequencies, and considerably reduce filter volume to improve power density. A stacked buck converter was eventually selected after reviewing the existing solutions and discussing their advantages and disadvantages. A stacked buck converter is used as a basis to propose the transient response and output current ripple elimination effect, boundary limit control method, and low output ripple dead time modulation method to make individual improvements. The principle, mathematical derivation, small-signal model, and compensator design method of the improvement method are presented in detail. Moreover, simulation results are used to mutually verify the correctness and effectiveness of the improvement method. A stacked buck converter with 330-V input, 50-V output, and 1-kW output power was implemented to verify the effect of the low output current ripple dead time modulation. Experimental results showed that the peak-to-peak value of the output current ripple was reduced from 2.09 A to 559 mA, and the RMS value was reduced from 551 mA to 91 mA, thereby effectively improving the output current ripple. [ABSTRACT FROM AUTHOR]

In this study, an optimization procedure was proposed for the magnetic component of an integrated transformer applied in a center-tap phase-shifted full-bridge converter. To accommodate high power–density 0demand, a transformer and an output inductor were integrated into a magnetic component to reduce the volume of the magnetic material and the primary and secondary windings of the transformer were wound on the magnetic legs to reduce conduction loss attributable to the alternating-current resistor. With a focus on the integrated transformer applied in a phase-shifted full-bridge converter, circuit operation in each time interval was analyzed, and a design procedure was established for the integrated magnetic component. In addition, the manner in which output inductance was affected by the mutual inductance between the transformer and the output inductor in the integrated transformer during various operation intervals was discussed and, to minimize circuit loss, a design optimization procedure for the magnetic core was proposed. Finally, the integrated transformer was applied in a phase-shifted full-bridge converter to achieve an input voltage of 400 V, an output voltage of 12 V, output power of 1.7 kW, an output frequency of 80 kHz, and a maximum conversion efficiency of 96.7%. [ABSTRACT FROM AUTHOR]

Purpose: To investigate whether there is any change in the subcortical gray matter of patients with neocortical focal epilepsy without visible magnetic resonance imaging (MRI) abnormalities., Methods: MRI morphometric parameter data from 24 patients and 29 neurologically normal controls were analyzed. All of the MRI scans were reported to have no any anomaly. Differences were evaluated by vertex-wise shape analysis., Results: A shape analysis showed significant surface reductions at the anterior-ventral and the posteriordorsal aspects of the bilateral thalami, the global left caudate nucleus, part of the bilateral dorsal putamen and the left hippocampus., Conclusion: Patients with focal seizures and secondary generalization had smaller volumes and microstructural anomalies in subcortical gray matter regions.

Powerline interference always disturbs recordings of biomedical signals. Numerous methods have been developed to reduce powerline interference. However, most of these techniques not only reduce the interference but also attenuate the 60 Hz power of the biomedical signals themselves. In the present study, we applied the S-transform, which provides an absolute phase of each frequency in a multi-resolution time-frequency analysis, to reduce 60 Hz interference. According to results from an electrocardiogram (ECG) to which a simulated 60 Hz noise was added, the S-transform de-noising process restored a power spectrum identical to that of the original ECG coincident with a significant reduction in the 60 Hz interference. Moreover, the S-transform de-noised the signal in an intensity-independent manner when reducing the 60 Hz interference. In both a real ECG signal from the MIT database and natural brain activity contaminated with 60 Hz interference, the S-transform also displayed superior merit to a notch filter in the aspect of reducing noise and preserving the signal. Based on these data, a novel application of the S-transform for removing powerline interference is established.