Embodiments are described herein for managing licenses of media files on playback devices in a media system. An E-beam firing bar engages the channel and selectively engages the anvil during distal firing movements, wherein the tissue is severed and stapled driven upward from the staple cartridge to form against the anvil. The measured spectrum is Fourier transformed to obtain an axial spatial cross-correlation between the signal and reference fields with near 1 m depth-resolution. A rectifier circuit prevents current backflows into the DC voltage source to prevent overheating and device failure. The sensor unit comprises the anchor and the sensing device placed and secured within the bore of the anchor so that a sensing element of the sensing device is exposed for sensing the physiological parameter within the cavity.