The present invention provides a compound of the formula:a pharmaceutically acceptable salt or a prodrug thereof, where R1, R2, R3, R4, R5, R6, R7, R8, R9, Y, Z1, m, n, and p are as defined herein. Each electronic device may be configured to register at one of the conferencing endpoints for a teleconference between the plurality of conferencing endpoints based upon communication with a respective NFC device associated with the one of the conferencing endpoints. The unit cell further includes an output multiplexer for selectively coupling the first capacitor and the second capacitor to an output signal line during respective charge signal readout periods.