Biometric matching technology, in which a watch list is managed, multiple images of a potential suspect are accessed, and parallel pre-processing of the multiple images is controlled. The switched capacitor amplifier is capable of operating so as to eliminate a chargedischarge time difference between an input capacitor and an output capacitor. The analog signal and the respective output signals of the amplifier stages are summed in a summation stage to form a sum signal. In addition, other formulations or treatments, such as one or more sealing compositions, or a final coating formulation can also be used to impart other desired characteristics such as treatment durability. If G1,2 is less than g1+g2 by more than a threshold value, the system calibrates a phase relationship between the first and second pairs of antennas. The method includes selecting at least a first information item from a first index on the first handheld computer, and signaling the first information item to the second handheld computer.