The present invention provides compositions, kits, and methods suitable for cleansing the colon before colonoscopy. The catalyst comprises an active aluminum oxide, a first ceriumzirconium mixed oxide and a second ceriumzirconium mixed oxide. The system identifies storage volumes currently available to the portable computer and identifies storage volumes previously accessible to the portable computer, but not currently accessible to the portable computer. The conductors are connected at one end of the cable in series such that if the conductors are connected at the other end of the cable to respective poles of a power supply equal currents flow in opposite directions through adjacent portions of the conductors, substantially eliminating electromagnetic radiation from the cable.