This paper deals with the influence of the spatial distribution of laser beam intensity on the dynamic of laser melting, the surface tension driven convection, and the distribution of alloying elements in the molten pool. The shape of the melting front boundary, the flow pattern, as well as the concentration fields of alloying elements are evaluated for different pulse laser actions operated by different types of nonmonotonic spatial distributions of energy density flow. The relationships between the shape of the laser beam and the structures of the alloyed zones are determined.

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A theory for the y-ray background involving cosmic-ray interactions at high redshifts has been re-examined using improved computational techniques and more realistic radiation fields. Comparison with observations shows good overall agreement but a possible discrepancy in the 10-100 MeV range.

Extensive new data on the bound odd-parity spectrum of krypton have been provided recently by two-step laser spectroscopy experiments. Highly excited levels belonging to seven Rydberg series n d or ns converging to the ionisation limit have been observed, but some series are difficult to assign. Therefore, by means of multichannel quantum defect theory (MQDT) we have performed the analysis of all available energy data relevant to the J = 0, 1, 2, 3 odd-parity bound spectra of krypton. These studies allow us to identify all the newly observed highly excited Rydberg series by connecting the new data with previous work relevant to the low-energy range. Perturbations of nd and ns principal Rydberg series by the lowest members ns' and nd' of Rydberg series converging to the second limit occur in the low-energy range; these perturbations are successfully interpreted. The energies of unknown levels are predicted and a new value for the ionisation limit is provided. Additional information on the fine structure of highly excited configurations is obtained by means of the Slater-Condon method. The Slater integrals of highly excited configurations are determined and the J1 coupling scheme of levels is discussed.

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