Techniques for detecting fluorescence emitted by molecular constituents in a wall of a body lumen include introducing an autonomous solid support into the body lumen. A read command is received from a host to read data from a first data sector. The service plug is a member independent of an ordinary service plug arranged at the power storage device. A time difference between the first and second signal transit times at the reference point is calculated to determine the clock drift. Corresponding pharmaceutical compositions, methods of treatment, methods of synthesis, and intermediates are also disclosed. The resulting decision logic improves speech intelligibility when talking under noisy conditions.