The invention provides methods for pairwise sequencing of a double-stranded polynucleotide template, which methods result in the sequential determination of nucleotide sequences in two distinct and separate regions of the polynucleotide template. The hub assembly includes a hub shell with a first flange and a driver side flange. The first, second, and sixth current mirror circuits receive a first power supply voltage, and the third, fourth, and fifth current mirror circuits receive a second power supply voltage. The prediction type may be either signaled explicitly, such as by providing a code word in the bit stream, or may be inferred implicitly by selected values or levels of a coding variable. Along the edges of the openings of the first concave and the second concave, ridges are formed. These infrared radiation absorbing dyes exhibit a reduced tendency to crystallize in the imageable layers in the presence of tetraaryl borate counter anions and therefore provide improved shelf life.