An x-ray computed tomography apparatus has an x-ray source that can be rotated around a system axis and a diaphragm that is disposed downstream from the x-ray source in the ray propagation direction for gating a fan-shaped ray beam that irradiates a subject. The techniques employed by the system effectively eliminate damaging gain hot spots and lower ASE and ESA thresholds, thereby increasing laser peak and average power levels. The substance transfer device is capable of simultaneously dispensing substances into two or more receptacles or simultaneously removing substances from two or more receptacles. In the transmitting computer device, the security association for processing a data packet coming from the transmitting virtual router is selected on the basis of the identification of the transmitting virtual router within the security association. After reaching this nominal temperature the resistor is contacted in the medium.