A bumper guard for attachment to a sports racquet. A polarization state in which transmission and reception optical signals within an optical phase shifter which enters one route of the two optical signals are made orthogonal to each other is provided, to thereby distinguish the transmission and reception signals of the round trip from each other. A control unit causes to be re-executed using the new value all instructions in the microprocessor that used the current architectural segment register contents as a source operand and that are newer in program order than the architectural segment register-loading instruction whenever the comparator indicates the new value does not equal the current contents. According to another embodiment, a transistor includes a substrate, and first and second shallow trench isolation regions in the substrate. The inlet section may be associated with the liner outlet portion.