Samples of nominal composition Bi,_._,Pb,Sb,Sr,Ca,Cu,O (x = 0 -0.8, y = 0 -0.3) were prepared and investigated by x-ray, DTA, TG and microprobe analyses. T, was measured by resistive and magnetic (DC susceptibility) methods. The addition of antimony exerted a stabilizing influence on the formation of the 2223 phase, the solubility of Sb being 60.1 mole. The optimal temperatures of t h e formation of the 2223 phases with dinerent Pb a n d S b content are in the range 83W4O"C. Deviation from the optimal temperature of about 1-2°C can b e the cause of a sharp decrease in the volume of the 2223 phase. The anomalies at 240 K revealed a temperature dependence of resistance and magnetic susceptibility for some samoles with and without Sb
The known equivalence of the honeycomb eight-vertex model with an Ising model in a non-zero magnetic field is derived via a direct mapping. Compared with a previous derivation which uses the generalised weak-graph transformation, the new method is simpler and more direct, and can be extended to other considerations.
Multiobjective radiotherapy planning aims to capture all clinically relevant trade-offs between the various planning goals. This is accomplished by calculating a representative set of Pareto optimal solutions and storing them in a database. The structure of these representative Pareto sets is still not fully investigated. We propose two methods for a systematic analysis of multiobjective databases: principal component analysis and the isomap method. Both methods are able to extract the key trade-offs from a database and provide information which can lead to a better understanding of the clinical case and intensity-modulated radiation therapy planning in general.
We derive an improved prescription for the merging of matrix elements with parton showers, extending the CKKW approach. A flavour-dependent phase space separation criterion is proposed. We show that this new method preserves the logarithmic accuracy of the shower, and that the original proposal can be derived from it. One of the main requirements for the method is a truncated shower algorithm. We outline the corresponding Monte Carlo procedures and apply the new prescription to QCD jet production in e + e − collisions and Drell-Yan lepton pair production. Explicit colour information from matrix elements obtained through colour sampling is incorporated in the merging and the influence of different prescriptions to assign colours in the large N C limit is studied. We assess the systematic uncertainties of the new method.
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