A motor power train which includes a reducer for amplifying motor drive torque, a differential device with a clutch mechanism and a differential gear unit to allocate the drive torque to wheels, and a casing for housing them. A channel state information reference signal configuration is selected such that at least one CSI-RS can be transmitted to the wireless device in a subset of subframes assigned to relay backhaul transmissions. Controlling access to electronic content on a client device can involve locally determining whether access to the electronic content will be allowed, blocked, or will depend upon further analysis performed by a remote device, such as a server. Furthermore, the material can be annealed. The preferred foam deck has first and second panels interconnected by one or more webs. Preferably the impact absorber forms an elongatable structure, e.