[en] The results of a theoretical study of the effects of cloud geometry on the transfer of incident solar radiation is presented. These results indicate that a three-dimensional description of cloud geometry is a necessary prerequisite to the accurate determination of the emerging radiation field. Models which make the plane parallel assumption are therefore frequently inadequate. Both a Monte Carlo method and an analytic method were used to model the three-dimensional transfer of radiation. At the expense of considerable computation time the Monte Carlo model provides accurate values of the fluxes and intensities (averages over π/30 steradians) emerging from clouds which can be described as a set of connected cuboidal cells, each cell being homogeneous with respect to extinction coefficient, single scatter albedo and phase function. The analytic model, based on an extension of Eddington's approximation to three dimensions and to anisotropic scattering, is efficient to use, but is restricted to clouds made up of a single cuboidal cell and is more accurate for large clouds than small ones. By an iterated approach, involving integration of the source function along line of sight, the analytic model provides both fluxes and intensities of the emerging radiation at any specified point on the cloud's surface. These models were both applied to a systematic study of the transfer of solar radiation in isolated cuboidal clouds of arbitraty dimensions, the results of which illustrate the importance of considering the total cloud geometry in any attempt at realistic modelling. A study of the transfer of radiation in stratiform clouds with turretted top surfaces also indicated that even for these clouds the plane parallel assumption was often not tenable

[en] The Sizewell B inquiry on a proposed new nuclear power plant on the Suffolk coast appears to have been objective and accurate, but whether it is a useful decisionmaking tool and vehicle for real public participation in technology assessment is open to question. The hearing process was intensified by the controversial nature of US pressurized water reactor (PWR) technology in this first test of public acceptance in Britain, where the decision was made earlier to go with gas-cooled reactors. After reviewing the PWR concerns and the first year of the inquiry, the author concludes that the safety review policy has limited the examination of many specific aspects of the design while encouraging objectors to look at generic issues that are largely insoluble. Sizewell, he feels, may encapsulate lessons for other countries in facing risk/benefit questions involving values. 46 references

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[en] 1 - Nature of physical problem solved: Time variation of xenon and samarium poisoning due to space-dependent flux distribution. Conventional space independent poisoning also computed. Power variations given in histogram form. 2 - Method of solution: Three-dimensional flux and adjoint distributions are synthesised from 1- and 2-dimensional runs. Fluxes are sorted into n equal intervals and flux adjoint weight is calculated for each interval. This weighting function is then used to compute reactivity worth of poisons as function of time. N is normally of order 100

[en] The residue and extraction of technetium-labelled methylene diphosphonate (sup(99m)Tc-MDP), a substance used in bone scanning, was examined in the canine tibia and found to be low. Examination of washout curves suggested that there were four compartments in cortical bone, a vascular, a perivascular, a bone fluid and a bone compartment. After an osteotomy in the canine tibia the residue of sup(99m)Tc-MDP increased. This was believed to be due to an increase in the blood supply to the bone and to an associated increase in new bone available for exchange. Bone scanning in a fracture is therefore a reflection of the vascular status of the bone being examined and of the uptake by bone. This is dependent on there being an adequate blood supply to the bone and an increased number of mineral-binding sites. (author)

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[en] Transformer--rectifier flux pumps using thermally switched Nb₃Sn cryotrons are being investigated as a loss make-up device for the proposed isochorically operated (sealed) superconducting magnets for the Canadian Maglev vehicle. High currents (1000 A) were obtained in an experimental flux pump using inductive current transfer and operating at 2 Hz

[en] The extragalactic radio source 3C 303 has been mapped with approximately 1 arcsec resolution at a frequency of 408 MHz. The source displays a prominent one-sided jet which points towards a complex group of hotspots and confirms a physical association between the two sides of the source. Little evidence is found of an association of the radio structure with the nearby quasar of discrepant redshift. (author)