A computer readable storage medium tangibly embodying machine-readable digital data arranged to facilitate expedited searching. The method comprises the steps of receiving an encoded data stream, the encoded data stream generated by encoding a data stream by a duty factor representing a value of the data in the data stream; and decoding the encoded data stream according to the duty factor of the encoded data stream. The resultant structure is selectively etched to a given depth to form trenches. Embodiments of the present invention are particularly beneficial when used with a rate responsive cardiac stimulation device. A gas turbine engine annular fan frame incorporates the vanes in an annular row of composite outlet guide vanes extending radially between and connecting radially inner and outer rings of the fan frame. Also provided herein are vectors and host cells comprising those nucleic acid sequences, chimeric polypeptide molecules comprising the polypeptides of the present invention fused to heterologous polypeptide sequences, antibodies which bind to the polypeptides of the present invention and to methods for producing the polypeptides of the present invention.