In a distributed network, a method of recursively linking a multiply modified multimedia asset to an original digital negative of the multimedia asset is disclosed. Following completion of the backup, a record is prepared indicating that all data objects exist in the specified target storage, regardless of whether each data object was replaced with a predetermined bit pattern rather than being physically written to the specified target storage. The sensor further includes a device for passing an alternating current from the first to the second sensing elements through an ionic solution contacting the sensing elements. The solar-powered ball provides a pet toy. The method is carried out under atmospheric pressure or at pressures that differ only slightly from the atmospheric pressure. The system and method employs novel eye tracking and blink detection techniques in order to select images for transmission.