[en] The first results of a joint CEA/CNEN neutron propagation program conducted on the source reactors HARMONIE and TAPIRO are presented. In both cases, a buffer zone representative of the blanket of a commercial fast power reactor is interposed between the source reactor and the medium in which neutron propagation is measured. This buffer zone provides a realistic source spectrum to be propagated. Experimental results are compared to older results obtained without the buffer zone. The effect of the source spectrum on neutron propagation is discussed, as well as the coherence of the results obtained with the two installations

[en] Cerebral blood flow CBF was studied using a rapidly rotating Single Photon Computerized Emission Tomograph SPECT with high sensitivity, the TOMOMATIC 64. Xenon-133 administered by inhalation was compared to isopropyl-iodo-amphetamine labelled with Iodine-123 IAMP-I-123 injected i.v. in patients in the chronic phase some months after a stroke. The early IAMP-I-123 image taken over the first 10 minutes showed the same CBF dominated distribution as Xe-133. Over the following 2 to 5 hours two distinctly different IAMP-I-123 images were found. Persistent low uptake was found over hypodense areas, emolission having virtually no flow or metabolism. Delayed uptake with disappearance of side-to-side asymmetry was found in areas with CBF, but without lesions on X-ray computerized tomography CT. The delayed IAMP-I-123 uptake therefore seems to reflect a more intact state of the tissue than the persistent low uptake. (author)