A heat exchanger has a connector for connecting a receiver tank brazed to a header pipe and the receiver tank connected to the connector by male screw parts, wherein the connector is formed to have a brazing face against the header pipe narrower than a mating face against the receiver tank. The present invention provides methods and compositions relating to altering floral transition in plants. The home base station is capable of sensing the presence of the mobile telephone in its coverage area and subsequently establishing contact with the mobile telephone, if the mobile telephone is registered with the home base station.