An Energy-Latency-Efficient MAC Protocol for Wireless Sensor Networks

Roller or in-line roller skate including a boot associated with an upper plate of a frame on which the skating wheels are arranged, and having a braking device constituted of a friction element connected to activating mechanism interposed between a journalled rear portion of the boot and the friction element, so as to bring the latter into a frictional contact with the ground, in view of a braking during a rearward rocking of said journalled portion of the boot, caused by the skater, wherein the friction element is connected to the activating mechanisms via amplification mechanisms that are capable of increasing its travel with resect to that of the activating mechanism.