Apparatus and methods are provided for performing cell growth and cell based assays in a liquid medium. The circuit has a latching switch that is electrically connected to a first source of power and adapted to provide latching power of the differential. The robots have picker mechanisms that can manipulate items in the storage cells, and displacement mechanisms that allow the pickers to move between rows of storage cells. A second diode couples the diode node to an output node. The golf ball has improved aerodynamic performance due to dimples and achieves a long flying distance. An alkaline etching solution is used that contains salts of alkali metals in sufficient concentration to increase the boiling point of the resulting alkali-metal-containing solution to temperatures in excess of about 100 up to about 150\xb0 C.