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It is shown that a correct coordinate transformation method leads to the well known LSS transport equations worked out in detail by Sanders in 1968. Some incorrect statements in the PRAL - Algorithm obtained by Biersack in 1982 are critically discussed. [ABSTRACT FROM AUTHOR]

Recently, Raychaudhuri published a paper on electronic energy bands in threedimensional lattices. The purpose of the present communication is twofold: (1) to point out that one of the simplifying assumptions made in I is invalid, and (2) to point out the possibility of obtaining a correct procedure which retains many of the advantages of Raychaudhuri's approach. [ABSTRACT FROM AUTHOR]

The paper of Dersch et al. [1], concerning the results of inelasticAr + Cu collisions at 1.8 and 0.9 GeV per nucleon, is discussed. The authors have explained their experimental results on the basis of the concept of anomalons of a lifetime of ∼2·10 s and/or as 'inconsistency with known nuclear physics'. It is shown that such conclusions are untenable, and the data presented in the cited paper can be explained within the frame of known physics. [ABSTRACT FROM AUTHOR]

In continuation of a previous paper we investigate the interaction of one or several cavity modes described by standing waves with a set of atoms each with two optically active levels and a homogeneously broadened line. The modes may or may not be at resonance with the atomic transition. The pumping is again introduced explicitly. A deeper motivation of its mathematical formulation is given in the Appendix, together with the description of another pumping mechanism. If the time-dependent response of the atomic system is small, the following results are obtained: Above threshold several modes can exist due to the different spatial inversion of the atomic inversion. The amplitudes fluctuate around values obeying algebraic equations which are for moderate pumping power equivalent to those of a previous paper by Haken and Sauermann. The phases may, however, undergo an undamped diffusion process, giving rise to a linewidth, which, if properly normalized, is that of single mode operation. The linewidth is determined explicitly for several physical situations. Finally, the complex degree of mutual coherence of two modes from the same laser is compared with that of two different lasers. [ABSTRACT FROM AUTHOR]

It is shown that a previous calculation of the escape factor G for moderate values of the optical depth yields to large values. [ABSTRACT FROM AUTHOR]

In the last paper on the polarizabilities in the 6 snf Rydberg series of barium results for the 6 snfF levels with n=13-40 are reported. The scalar and tensor polarizabilities are analyzed using existing data on the adjacent even-parity 6 snd D series as well as data on neighbouring 6 sng G and G series derived from the polarizabilities of the 6 snf F and F series. This results in information on the to a large extent unknown 6 sng G series and confirms the perturbation of this series in between n=15 and 16 by the doubly excited 5d7dG level. A tentative two-channel quantum-defect analysis is presented. In conclusion the results on the 6 sng configuration deduced from the study of the quadratic Stark effect in the 6 snf configuration are summarized. [ABSTRACT FROM AUTHOR]

The temperature dependence of the thermal resistivity of alkali metals lithium, sodium, potassium, rubidium and caesium is determined within the free electron approximation by using Krebs's model for the phonon dispersion relations. The normal and Umklapp contributions are obtained separately from an improved method following the procedure of an earlier paper. The results of calculations are compared with available experimental information. The theoretical and experimental resistivity curves are found to be of similar nature, but they show considerable disagreement at low and high temperatures. [ABSTRACT FROM AUTHOR]

A short derivation of the Random Phase Approximation of angular momentum waves in solid Ortho-H is presented. Methods and results of papers on the same topic are compared. [ABSTRACT FROM AUTHOR]