A dynamic swing-aid device used to improve the golfer’s swing action. The method comprises: measuring a reference clock according to a free-run clock to produce a counter signal in a normal mode; suspending the reference clock; and generating the output clock according to the counter signal and the free-run clock in a power-saving mode. The provided pulse sequences also provide a mechanism for longitudinal mixing, which significantly increases the efficiency of magnetization transfer and thereby increases signal-to-noise ratio. The signal processor retrieves the spatial location, determines a beamforming phase shift derived from the spatial location for each transducer element in the receive aperture, and applies the respective phase shift to each receive signal. 5 and have an average primary particle diameter from 5 nm to 300 nm, preferably between 5 and 100 nm, and M is at least one cation dopant. Structure is provided to prevent excessive additional rotation of the hinged elements of the hinged guard after the tip of the needle cannula is shielded.