appropriate colour channel the horizontal axis is pcr cycle the horizontal line marked with an arrowhead on the right hand vertical axis is the threshold line which is placed manually after correction for background fluoresence amplification curves crossing the threshold line are considered positive and the fractional pcr cycle where the amplification curve crosses the threshold line is the threshold cycle c t given in the accompanying report fig4 shows amplification of the internal control hpv6 fig1 shows amplification of hpv18 in multiplex group 1 the two positive curves are positive controls there are no hpv18 positive samples fig2 shows amplification of hpv52 in multiplex group 1 4 positive curves are visible the orange and grey curves to the right are positive controls the two blue curves are positive samples samples four and 6 containing hpv52 fig3 shows amplification of hpv59 in multiplex group 1 the two positive curves are positive controls there are no hpv59 positive samples fig4 shows amplification of hpv39 in multiplex group 2 the green curve is a positive control containing the target types of group 2 in a second positive control containing all fourteen target types hpv39 failed to amplify the black curve is a strongly positive sample sample 18 containing hpv39 fig5 shows amplification of hpv51 in multiplex group 2 six positive curves are visible the green and brown curves crossing the threshold line at cycle 29 are positive controls the four remaining curves are hpv51 positive samples two of which samples.