Measurements of higher harmonics of the ac voltage response in YBCO thin film strips under low amplitude and low frequency harmonic excitation, as a function of temperature, show a non linear response of the conductivity in the superconducting transition interval. The third and fifth harmonics of the local voltage as a function of T exhibit a peak near Tc and their amplitudes seem to be closely related to the T-derivative of the first harmonic. The peaks are linearly dependent on the current amplitude and do not depend on frequency. The observed data are partially interpreted in terms of ac current induced thermal modulation of the sample temperature added to strong thermally activated fluctuations in the transition region. The fit of the model to the data gives information of some sample properties such as zero temperature critical current, zero onset resistance and thermal boundary conductance.

The purpose of this study was to make an investigation of the use of motion pictures and film strips in the coaching of athletics in a selected group of high schools in Texas. It was proposed, also, to formulate conclusions as to the practices utilized in connection with these visual aids in the coaching technique and to make recommendations for their use by coaches as outgrowths of the study.