Bianchi surfaces in R3 and deformation of hyperelliptic curves

New solutions of the problem of describing hyperbolic surfaces of specified negative Gaussian curvature are obtained. The answer is given in terms of 9 functions.Translated from Matematicheskie Zametki, Vol. 52, No. 3, pp. 78–88, September, 1992.The first author (D. A. K.) wishes to express his appreciation to A. I. Bobenko for useful discussion.     

On the optimization of a CAPM portfolio using lower partial moments as measure of risk and using the possibility of safeguarding its loss

Using a portfolio built from bonds (investment without volatility) and shares (investment with volatility) corresponding to the CAPM we calculate the possible loss of this portfolio. The loss is measured by a so-called lower partial moment of the rate of return of the portfolio. Using this loss, we optimize the composition of the portfolio with respect to this loss. Also we investigate the optimization of the portfolio when the loss can be underwritten by an insurance. Concerning the premium of this insurance contract, we show that when the premium is defined inadequate, e.g. proportional to the investment or proportional to the amount of investment in shares, the optimal portfolio consists only of investment in shares. When the premium is defined more suitable, e.g. proportional to the loss, the optimal portfolio is built by an investment in bonds and shares.     

Cation electron densities in the orthorhombic phase in YBa2Cu3O6+x ceramic

Donetsk Technical Physics Institute, Academy of Sciences of the Ukrainian SSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 31, No. 4, pp. 12–16, July–August, 1990.     

Reactions of some chlorohydrins with uracils

Conclusions By the reactions of uracil and 6-methyluracil with chlorohydrins 3-(hydroxyalkyl)- and 1,3-bishydroxyalkyl-uracils were prepared, and their structures were proved.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1327–1329, June, 1968.We thank V. D. Kochkina and S. A. Flegontov for determining the IR spectra.     

New effect in near-field thermal emission

A near-field effect has been discovered experimentally in thermal radio emission of an absorbing dielectric medium. It is related to a specific character of the distribution of a quasistationary field component near a radiating surface. The effect consists of the fact that the effective depth of the received emission formation appears to be less than the skin-layer depth and depends on the size of the receiver antenna and its height above the surface. It can be considered as a new source of information about depth temperature distribution. A theory has been developed that allows for determining the relative contribution of wave and quasistationary components to the Plank emission received near the surface.