Abstract: A hydraulic actuator with a minimal closed height includes a housing (11), a chamber (12), and a fluid inlet (13) formed within the housing and arranged for communicating high pressure fluid to the chamber (12), the chamber (12) being partially divided into an inner portion (P1) and a radially outer portion (P2) by a longitudinally extending sleeve (123) having an open end (1231) proximal to a base (121) of the chamber (12) and spaced apart therefrom, the outer portion (P2) being arranged to communicate high pressure fluid from the fluid inlet(13) to the inner portion (P1) through a space (S) defined between the end (1231) of the sleeve (123) and the base (121), and the inner portion (P1) being adapted to receive a piston (100) such that the piston (100) is slidably actuable in dependence on the high pressure fluid received from the outer portion (P2).

Abstract: A transmitter (100) for transmitting radio signals to a receiver comprises a data generator (101) which generates a plurality of groups of information data. A radio condition processor (107) determines a radio environment characteristic, such as a propagation channel path loss or an interference level. A subset processor (103) generates a data message by selecting a subset of the plurality of groups of information data in response to the radio environment characteristic. The data message is then transmitted by a transmit unit (107). The invention may provide flexible and efficient discontinuous transmission operation which may be particularly suitable for discontinuous transmission of control data. The invention may for example reduce interference in cellular communication systems.

Abstract: A method of operating a cellular communications system, the method comprising a subscriber unit, e.g. mobile station or user equipment such as a mobile telephone, participating in a session context such as a session conference call that has been set up using a session initiation protocol such as Internet IP Session Initiation Protocol; a first user inputting a voice message to the subscriber unit; and the subscriber unit transmitting the voice message to a second user by means of the session context. The voice message is input on a push-to-talk basis and transmitted over a push-to-talk bearer path.