Methods and apparatus, including computer systems and program products, for executing a query, for example, a query for a document similar to another document. A decoder includes a syndrome memory, a state memory, and decoding circuitry communicatively coupled to the syndrome memory and the state memory. The method of invention further provides foamers that are compatible with a reverse osmosis membrane. A state machine running on the portable computer system’s Super IO compares the identification signal and a power available signal from an internal charger to determine state of the external power source and indicate the state to a user. Other aspects of the invention are a composite structure comprising a porous support and a porous nanoweb comprising fibrous structures comprised of one or more compositions of formula and a method for making said composite structures.