A portable transportation assembly 10 having a pair of wheels 40, 42 which may be selectively raised and lowered and which is adapted to transport a bathroom assembly 200 in an easy and efficient manner. An intermediate potential region different from the ground potential of an aberration corrector is provided in the space between the stages of multipole lenses constructing the aberration corrector to adjust a potential. The virtual call center performs Interactive Voice Response and Automated Call Distributor functions to the callers on behalf of subscribers of the virtual call center for enabling communication between the callers and the subscribers. A darkmap is rendered onto the polygon by subtracting from the pixel values in the frame buffer the darkmap values modulated by the frame buffer alpha values. A command is then transmitted from the tracking device management system to the tracking device through a tracking device communication link to configure the tracking device to reflect the modified configuration settings. A wireless packet transmitter transmits the capsulated packet between the base station and the at least one wireless LAN.