Abstract: An apparatus for querying a central service dials telephone numbers to establish contact with the central service, and accesses services housed in the central service. The geographical location of the apparatus is stored in a tie unit and sent to the apparatus upon request. The apparatus forwards this information to the central service that then provides information about facilities (e.g., restaurants, sports venues, theaters, etc.) at that location.

Abstract: The invention relates to a method of preparing an oxide of formula Li.sub.x Mn.sub.y O.sub.z, in which x lies in the range 0 to 2, y lies in the range 1 to 3, and z lies in the range 3 to 4.5, x, y, and z being such that the oxide has a composition close to LiMn.sub.2 O.sub.4. According to the invention, the method comprises the following steps:a) a polymer complex of lithium and of manganese is prepared in the form of a gel or of a xerogel by causing a reducing polymer, copolymer or polymer mixture possessing complexing functions for lithium and manganese to react in a common solvent with an oxidizing lithium salt and with an oxidizing manganese salt, and by evaporating off the solvent, partially or in full; andb) the resulting lithium and manganese polymer complex is mineralized by the explosive oxidation-reduction technique to recover fine amorphous particles of the oxide of formula Li.sub.x Mn.sub.y O.sub.z.