The present invention provides a method and apparatus for dispensing small volumes of selected substances, such as biological reagents or samples, onto substrates. A stopper is formed on part of the incision opening. Further provided herein are methods for treating or preventing various diseases and disorders by administering to a patient one or more TNF\u03b1 andor PDE4 andor B-RAF inhibitors. The common-mode level adjust circuit alters a common-mode level of a differential input signal to be substantially equal to a desired common-mode level and the tuning circuit provides a compensation voltage to the common-mode level adjust circuit based on a difference between the common-mode levels.