Sensory qualities of the phantom hand map in the residual forearm of amputees

OBJECTIVE: Most amputees experience referred sensations, known as a phantom hand map, on the residual forearm, where touch on specific areas is perceived as touch on the amputated hand. The aim of this study was to evaluate the sensory qualities of the phantom hand map.METHODS: In 10 traumatic forearm-amputees touch thres-holds and discriminative touch of the phantom hand map were assessed and compared with corresponding areas on the contralateral forearm. The study assessed the localization of touch on the phantom hand map, and how distinct and similar to normal touch the referred feeling was.RESULTS: Similar touch thresholds were seen in the phantom hand map and the control site. Tactile discrimination, requiring both detection of stimulus and interpretation, was significantly better in the phantom hand map.CONCLUSION: This explorative study suggests that the phantom hand map and the superior tactile discrimination seen in the phantom hand map are based on adaptations within the brain. Further studies investigating the neural basis for the phantom hand map are needed

Modelling the Radioactivity Induced by Slow-Extraction Losses in the CERN SPS

Resonant slow extraction is used to provide an intense quasi-DC flux of high-energy protons for the Fixed Target (FT) physics programme at the CERN Super Proton Synchrotron (SPS). The unavoidable beam loss intrinsic to the extraction process activates the extraction region and its equipment. Although the radiation dose to equipment has an impact on availability, the cool-down times required to limit dose to the personnel carrying-out maintenance of the accelerator also pose important restrictions, and ultimately limit the number of protons on target. In order to understand how the extracted proton flux affects the build-up and subsequent cool-down of the induced activation, a model based on a simple empirical relationship has been developed and shown to predict the measured radioactive decay at ionisation chambers located along the extraction region. In this contribution, the empirical model is described, its strengths and limitations discussed, and its application as a predictive tool for estimating cool-down times as a function of extracted proton flux demonstrated