A method of establishing connection between users of mobile devices includes receiving at a computer a location of a first user from a first mobile device, receiving from a second mobile device a location of a second user having an acquaintance relationship to the first user, and sending a message to the first mobile device based on the proximity of the first user to the second user. If it is an insulator, the equipment, which generates the biasing magnetic field and supplies it to the magnetoresistive element, may contact directly to the magnetoresistive element. An operation selecting unit is provided which selects and causes a service implementation unit among the plurality of service implementation units that implement a service corresponding to the attribute information to operate. The method comprises comparing a ratio of invalid transactions to valid transactions for the particular client device or requested resource to a preestablished ratio threshold value. Said dry etching gas permits the formation of a pattern such as a contact hole with a high aspect ratio. Articles are also provided having limited satellite material.