The present invention provides the use of acetic acid derivatives and compositions in the treatment of insulin resistance, Type 2 diabetes and hyperlipidemia. The first processor is operable to compute first results responsive to instructions, the second processor is operable to compute second results responsive to the instructions, and the compare logic is operable to check at checkpoints for matching of the results. The invention further relates to a vehicle device, a beacon and a monitoring device for such a road-toll system. In a spectral discrimination step, the pixel-to-pixel separation for those pixels passing the spatial filter step is compared to a predetermined pixel spacing.