A simplified Viterbi detector for maximum likelihood detection of nine-bit QPSK symbols, employing a difference metric and two comparators, instead of using two state metrics and four comparators. A process for preparing C3-C19 alkyl- and aryl-thiotrifluoroacetates is also provided wherein a C3-C19 alkylthiol or arylthiol is treated with trifluoroacetic anhydride in the presence of organic base such as pyridine, a solvent such as dichloromethane and dimethylaminopyridine as a catalyst to form the desired C3-C19 alkyl- or aryl-thiotrifluoroacetate. The arms extend into a prepared space between the vertebrae to be fused. The transparent conductive layer constituting the first electrode unit contains conductive fiber and transparent conductive material. One method includes providing a print preview that reflects a consumable availability status and optionally proceeding with a print job.