An energy-absorbing structure is provided, which comprises two generally parallel metal sheets arranged to receive an impacting force against the uppermost sheet and cooperatively prevent an object supported by the uppermost sheet from impacting a basal surface. The frusto-conical sockets are formed of a material resistant to wear. Methods of treatment and combinations with other agents are also disclosed. An impedance of a faraday system is determined based on the discharge characteristics of a capacitor that discharges through the faraday system. The packet classification engine provides start indicators based on the packet classification to the programmable sub-engines to identify application programs to be executed.