Methods and apparatus of amplifying signals. Gene therapy, for example, requires successful transfection of target cells in a patient. Use of the system may provide prevention, treatment, or amelioration of diseases and disorders affecting the lens of the eye and which may benefit from IOL surgery. From that, a cumulative amount of inhalant inspired by the test subject may be determined during the course of the inhalation compound test. The drum has a structure in which the shaft projects from the bottom and is positioned with respect to the mounting surface by inserting the shaft into the mounting hole.