Abstract: In a method for regulating a position of an X-ray focus on the anode of an X-ray source of a scan unit of an X-ray imaging system, a combined actual position of the X-ray focus is determined by a combination of a measured position of the X-ray focus and a model-based position of the X-ray focus, which is determined based on a measured value of a deflection current. On the basis of the combined actual position and a target position, a manipulated variable is determined. On the basis of the determined manipulated variable, a regulation is performed to correct a deviation of the position of the X-ray focus from the target position.

Abstract: A PCR apparatus has a specimen chamber, a heating conduit which communicates with the specimen chamber, a cooling conduit which communicates with the specimen chamber, and a pumping device for pumping a gaseous or liquid medium through the heating conduit and/or the cooling conduit to the specimen chamber. The PCR apparatus further has a heating device, disposed separately from the cooling conduit, which communicates with the heating conduit and heats the medium located in the heating conduit c. The PCR apparatus has further a mixing device, which communicates with the heating conduit and with the cooling conduit, such that a ratio between a volume of the medium flowing per unit of time through the heating conduit and a volume of the medium flowing per unit of time through the cooling conduit to the specimen chamber is adjustable.