Figure 4

Signal Classification. Examples of global classifying regions. In the top picture the classification procedure based on WPT is applied on the interval 392-400 bp of the inter-Alu pattern. The classification is due to the presence of a single peak at different positions in the signals of the different twin couples Cn1, Cn2, Cn3, whereas it maintains the same position in the signals of a single twin couple. The wavelet function that performs the classification is positive in the interval 392-396 bp and negative in the interval 396-400 bp; therefore the convolution with the Gaussian peaks of the signal is the sum of positive and negative terms. The picture is obtained by multiplying the signals by the classifying wavelet function in order to illustrate the results of the WPT. The WPT coefficient is the sum of the positive and negative peak areas; therefore the WPT coefficient is positive for the couple Cn1, negative for the couple Cn2 and nearly zero for the couple Cn3 and a K value ≃1 is obtained in eq. (2). In the bottom picture the classification procedure is applied to a larger interval 120-160 bp. In such a case the WPT classification is due to the presence of a pattern of several peaks that have a significant variability among the signals of the different twin couples.