A spring motor and drag brake for use in coverings for architectural openings. The shell includes an evaporating section, a condensing section and an adiabatic section located between the evaporating section and the condensing section. From that internal representation, the system produces analog outputs representing the terminal screen. When it is determined that the mouse is positioned apart from the working plane, the microprocessor clears the displacement amount obtained from the communication interface of the optical displacement sensor, and meanwhile the microprocessor inform the computer that the mouse is apart from the working plane. The excised tissue can then be trapped between the electrode and core rod for removal from the body cavity. The base includes a connecting portion defining therein a pressure chamber in which a piston is disposed.