Abstract: A device for use in swimming comprising an elongate elastic member for positioning on the posterior forearm of a swimmer's arm, a first attachment means for attaching one end to a distal portion of the arm near the hand or wrist of the swimmer, and a second attachment means for attaching the other end to an intermediate portion of the arm near the swimmer's elbow. The device vibrates and creates turbulence on the posterior side of the forearm, enabling the swimmer to modify his or her stroke to maximise the generated turbulence, encouraging correct stroke technique.

Abstract: [Object] To ensure a maximum data transfer rate to achieve an improvement in throughput. [Solving Means] A CPU 114 determines whether or not time-dependent interference is present during communication with a communication partner. When it is determined that time-dependent interference is present, a PHY mode to be used in each zone is determined for each communication partner on the basis of transmission line state information or packet error detection information received via a CPU I/F register 113, and is set in a PHY mode table 115 through a CPU bus. A selector 116 selects a PHY mode to be used during the current transmission from the PHY mode table 115 on the basis of a destination ID of a communication partner and zone information (count value of a TimeZone counter 110) involved in next sending or reception, and sets the PHY mode in a packet composition/decomposition processing unit 118.