An object of the invention is to reduce the beam drift in which the orbit of the charged particle beam is deflected by a potential gradient generated by a nonuniform sample surface potential on a charged-particle-beam irradiation area surface, the nonuniform sample surface potential being generated by electrification made when observing an insulating-substance sample using a charged particle beam. In use, an attempt to perform an operation on predetermined data that is protected using a data leakage prevention system is identified. Prior to changing speed, the method may briefly remove a link signal or electrically isolate the network and the network interface to allow a peer to adapt to a new speed. The hierarchal social networking map is centrally located such that different collaboration types may utilize the hierarchal social networking map. The contactor units include conductive areas such as pads that are placed into contact with conductive terminals on devices under test. The method comprises the steps of generating a data stream including an identifier to be sent from a first to a second network switch, generating a number identifying one of the couplings from the identifier, and using the identified coupling for transfer of the data stream.