In one implementation, a method provides a graphical user interface to display representations of modifications to a knowledge entity that is stored in a knowledge base. An implantable electrode carrier has one or more electrical contacts on its surface. Along the front rim of each trough, the drum is provided with a drain opening, opposite to which means are provided for preventing, when the drain opening, during the rotation of the drums, is at the bottom, the penetration of solid matter through said opening. The angular velocity detector detects an angular velocity of the electronic apparatus, and outputs an angular velocity signal.