Embodiments of a simple and cost-free multi-time programmable structure for non-volatile memory cells are presented. It is an object of the invention to facilitate the alignment of the X-ray beam manipulating device with respect to an X-ray beam path or an X-ray beam focus of the radiation source. This estimated upstream packet loss information is used to make improved packet discard decisions. A contact arm is pivotally mounted in the housing. The housing cover displaces the upper bearing shell in the axial direction against the joint ball and generates a pressing force, which is partially compensated by a support element at the housing cover.