A server receives incoming data records comprising an ID value and respective user attributes corresponding to a user activity that originates at a user device. At least a portion of the interconnects for each tub have an exposed portion on a side of the submount and at least some of the plurality of the interconnects are not connected to other interconnects in the submount. The intensity calculation unit calculates for each partial area an intensity, which has a local maximum value when the difference is 0 and has a greater value as the absolute value of the difference is smaller.