A display device comprises a pixel array unit including a plurality of pixels, and power supply lines and a power supply scanner for supplying a power supply voltage switching between first and second potentials to each of the power supply lines, wherein each of the pixels includes a light emitting element, a sampling transistor, a driver transistor, and a holding capacitor. Methods and compositions for making such nanocomposites are also provided, as are articles comprising such composites. The customer information associated with the customer request is input into a traffic billing system. When the signals are in precise quadrature relationship, the error signal will be zero.