Optimality conditions in portfolio analysis with general deviation measures

Optimality conditions are derived for problems of minimizing a general measure of deviation of a random variable, with special attention to situations where the random variable could be the rate of return from a portfolio of financial instruments. General measures of deviation go beyond standard deviation in satisfying axioms that do not demand symmetry between ups and downs. The optimality conditions are applied to characterize the generalized ``master funds' which elsewhere have been developed in extending classical portfolio theory beyond the case of standard deviation. The consequences are worked out for deviation based on conditional value-at-risk and its variants, in particular.     

An Upper and Lower Solution Theory for the Problem （G＇（y））＇ ＋ f（t,y）= 0 on Finite and Infinite Intervals

A new upper and lower solution theory is presented for the second order problem （G＇（y））＇＋ f（t, y） = 0 on finite and infinite intervals. The theory on finite intervals is based on a Leray-Schauder alternative, where as the theory on infinite intervals is based on results on the finite interval and a diagonalization process.     

Use of magnetic probes for diagnostics of pulse plasma

Results of the measurement of proper magnetic field of a plasma cluster and of the distribution of current density in the cluster are given in this paper. The disturbances introduced into plasma by a probe are analysed and the applicability of internal magnetic probe is verified. The construction of probe is described.     

Zur Acetylierung von nichtreduzierenden Oligosacchariden

Ohne Zusammenfassung     

Transition to Chaos and Flow Dynamics of Thermochemical Porous Medium Convection

In a fluid-saturated porous medium, dissolved species advect at the pore velocity, while thermal retardation causes heat to move at the Darcy velocity. The Darcy model with the Boussinesq approximation in a square medium with a porosity of = 0.01 subject to two sources of buoyancy is used, to study numerically the dynamics of this so-called double-advective instability. The vertical walls of the medium are impermeable and adiabatic, while Dirichlet boundary conditions are imposed on the horizontal walls such that the medium is heated and salted from below. For an increasing ratio between chemical and thermal buoyancy, while keeping the thermal buoyancy fixed, a transition from a steady to a chaotic convective solution is observed. At the transition a stable limit cycle is found, suggesting that the transition takes the form of a Hopf bifurcation. The dynamics of the chaotic flow is characterized by irregular transitions between nonlayered and layered flow patterns, as a result of the spontaneous formation and disappearance of gravitationally stable interfaces. These interfaces temporarily divide the domain in layers of distinct solute concentration and lead to a significant reduction of kinetic energy and vertical heat and solute fluxes. The stability of an interface is described by a balance between the viscous drag forces in the convective layers and the buoyancy force associated with the density interface.     

A study of the velocity relations in the rail-accelerator without an external magnetic field

The experimental results of the measurement of the plasma cluster velocity in the rail-accelerator and their theoretical analysis are presented in this paper. The experimental set-up with simple pulse electromagnetic valve enabling to strike a discharge is described here. The dependences of the plasma cluster velocity on the voltags between electrodes and on different capacitances of the condenser battery are studied.     

Plasma acceleration by means of external magnetic field

Czechoslovak Journal of Physics -