An apparatus and a method for frequency locking are provided. More particularly, the compounds are useful for the treatment of diseases and disorders in which an interaction with the histamine H3 receptor is beneficial. The compressive sleeve deflects and compresses between the actuator assembly and the inner portion to decelerate movement of the actuator assembly, upon impact of the contact arm with the contact post. The STI regions comprise trenches in the substrate. The output-end clock signal has M clocks after the reception-end clock signal is generated, while the reception-end clock signal has N clocks as generated. Both the temperature and flow rate of gas through a segment of a gas knife can be independently controlled.