A fixed bed hydroprocessing system, and also a method for upgrading a pre-existing fixed bed hydroprocessing system, involves preliminarily upgrading a heavy oil feedstock in one or more slurry phase reactors using a colloidal or molecular catalyst and then further hydroprocessing the upgraded feedstock within one or more fixed bed reactors using a porous supported catalyst. Surgical instruments with passively flexible shafts extend through the curved cannulas. A receiver having a plurality of receiver elements is deposited on the TFT array to receive a received signal. The comparison module is operably coupled to compare the reference voltage differential with a differential voltage of the series impedance, wherein the comparison module generates an excessive current indication when the differential voltage of the series impedance compares unfavorably to the reference voltage differential.