A disc cutterbar with at least one cutterhead having a two-piece mounting hub, one piece rotatably driven and the other supporting a knife for severing standing crop material, with an epoxy layer bonding the two pieces together and forming a shear device therebetween. The method includes receiving application data describing characteristics of the software application, receiving update data describing at least one update applicable to the software application and reviewing the application data and update data to determine whether the at least one update is applied to the software application. A statistical question comprising, for example, cardinality estimations is received, wherein the question is posed by different database components, such as query optimizer, or execution engine. The same magnets generate a magnetic field, which compresses the plasma toward the center for confining the plasma within the plasma chamber. The valve control means controls the expansion valve using the opening degree detected in the opening degree detection operation. The present invention also relates to a method for calculating a compensating scattering 2N\xd72N matrix for a compensating network for an antenna system.