No abstract available

[en] Risk assessment plays an important part in the discussion of nuclear energy. The risks of nuclear energy are usually compared with other risks. The author of this paper presents a model for the calculation of rentability risks instead of accident risks. Differently from usual, the profits of nuclear industry are compared with possible accidents in some kind of game theory; a simple numerical example illustrates that especially in its political aspects the risk concept requires further consideration. The question whether the assumptions postulated here are generally valid will surely give rise to discussion. (orig./AK)

No abstract available

[en] We consider the notion of dynamical instability of many-body systems wherein states which are arbitrarily close initially are not close at some other fixed time. In controlling the dynamics of interacting systems of identical Fermions moving on a lattice, we isolate a basic mechanism which causes instability. (orig.)

No abstract available

No abstract available

[en] The role of the magnetic field in the model of the object SS 433 is pointed out. The region of high-energy plasma, which is strongly compressed around the stellar core owing to thermonuclear reactions on the one hand, and to the strong magnetic field on the other, can somewhat increase its size in the extreme case, but ejection from the core is possible only in the direction of the magnetic axis. The greater the field strength, the narrower are the two jets from the poles. The streams along the boundaries of the jets should gradually carry off part of the outermost field lines, so that the strong internal magnetic field may not necessarily be detected in observations. The shock wave produced during the first ejection from the poles sets the entire frozen-in plasma into radial oscillations; the corresponding pressure oscillations contribute to the observed variations in the velocities of the two polar plasma jets

[en] It is shown that the concept of atomic charge in molecules is a useful tool in studying electrostatic potentials at the nuclei which in turn are closely related to a number of molecular properties. Calculations executed on a selected set of widely different compounds provide extensive evidence that the semiempirical SCC-MO (self-consistent charge) atomic charges are equally successful in this respect as the ab initio DZ ones. (orig.)

[en] The behavior of shock waves in one-dimensional chains has been explored in a series of molecular-dynamics computer experiments. Three ''realistic'' nearest-neighbor pair potentials were considered: Lennard-Jones 6-12, Toda, and Morse: as well as three truncated forms: harmonic, cubic, and quartic. Over a wide range of shock strengths the particle velocity profiles and shock speeds for a given form of potential can be characterized in strength by αν, where α is the cubic anharmonicity coefficient and ν is the particle velocity in units of the long-wavelength sound speed. For strong shocks (αν > 1), steady hard-rod-like velocity profiles are observed for the ''realistic'' potentials and the quartic truncated form, but not for the harmonic or cubic forms. The shock thickness in the harmonic chain grows as the cube root of time, while the shock thickness in the anharmonic chain grows linearly with time, in proportion to shock strength. This evolution of the shock thickness is unaffected by initial equilibration of the chain at finite temperature. If either a heavy- or light-mass defect is included, the shock wave is reflected and the relaxation process is slowed behind the defect

[en] It is suggested that particle acceleration does not occur in the extended lobes of extragalactic radio sources, but only in the compact heads. Away from these, waves capable of accelerating particles may not propagate. Although wave generation within the lobes would allow acceleration there, it is not obvious that the plasma is sufficiently disturbed for this to occur. (author)