The PTI signal is linear with high concentrations of absorbing species [ 141, 145]; however, sample saturation can occur when the phase change between probe and reference beams becomes too large [ 142] and when the particles are too large to transfer the absorbed energy to the surrounding air within the probe beam modulation period (an issue common to PTI and PAS) [ 141, 142].
PM refers to a perfect match between the probe sequence and the Drosophila reference sequence, while MM (mismatch) refers to a single nucleotide difference between the probe and reference sequence that should affect RNA hybridization to the probe.
Results tended to be poorer with smaller intervals between the probe and reference, and also poorer in a lower octave range.
Figure 4 Mean results for unprocessed tones with both references D (a) and G# (b) in octaves 3, 4, and 5 with 1, 3, and 6 semitone intervals between the probe and reference tones.
When the sample is heated with a 'sample' laser (modulated at frequencies <100 Hz, [ 142, 143]), the optical path length of the probe beam changes because of the gas density change, which leads to a phase shift between the probe and reference beams, observable in the interference pattern.
Therefore, light is split into probe and reference light.
A second level of normalisation was used to address differential PCR amplification efficiency of individual probes between sample and reference amplifications, and adjusted the ratio for individual probes to the mean ratio among unaffected controls.
Such a quantitative measure is either an average log fluorescent intensity ratio (between sample and reference DNA) over multiple probes representing the CNP, or the log-intensity ratio of the best probe within the CNP region.
For each array, we excluded probes within the DMD region that were known to be deleted or duplicated for each patient; we kept probe data only for regions with equal genomic content between test and reference.
The ratios between the h TERT (green probe) and 5q13 reference gene locus D5S89 (red probe) signals were significantly correlated with the qPCR ratios of h TERT/ PIK3R1 gene content (Spearman correlation coefficient r=0.43, P=0.0006).
