The cassette half molding method molds one of upper and lower halves of the magnetic tape cassette by injection molding with an injection mold in which a gas vent pin for smoothing a flow of molten resin to be introduced in the cavity for molding a transparent or semitransparent window portion provided in the upper half. The method includes adding to contaminated water a composition including an aqueous mixture of at least one carbohydrate and at least one alcohol andor bacteriastat. The equation of motion represents a force applied on each lattice point of the destination image including potential energy force. The couplers may be implemented as polarization or intensity beam splitters positioned along the optical path. A user terminal comprises an antenna system capable of receiving multiple channels of broadband data broadcast transmissions in said frequency bands 2,310-2,320 and 2,345-2,360 MHz, 902-928 MHz, 2,400-2,483.