A locking artificial tree trunk including a first generally cylindrical, hollow trunk portion including an upper end, the upper end defining a notch, and a second generally cylindrical trunk portion including a body portion, a lower end having an insertable portion, and an upper end. The method comprises receiving a request for a certificate from the server and forwarding the request to a biometric certification server. A method for using the compound includes the steps of providing a heat generating electronic component with a first surface; providing a heat dissipating component with a second surface with which the first surface is to interface; and disposing the compound between the respective surfaces to effectuate efficient heat transfer therebetween. The heater power oscillation causes an oscillation in the sensor signal.