Nonlinear Amplitude Evolution of Baroclinic Wave Trains and Wave Packets

The weakly nonlinear theory of baroclinic wave trains and wave packets is examined by the use of systematic expansion procedures in appropriate powers of a small parameter measuring the supercriticality according to linear theory; well-known multiple scaling techniques are employed. Crucial importance is ascribed to the magnitude of parameters measuring dissipation and dispersion relative to each other and to the supercriticality, and equations describing the slow evolution in space and time of the wave amplitude are established for a range of parameter values. For vanishingly small dissipation the wave train equations have straightforward oscillatory solutions, dependent on initial conditions, and for large dissipation steady equilibration, independent of initial conditions, is predicted. For moderately small dissipation, however, a wide variety of behaviors is possible—including steady equilibration, single and multiple periodicity, and aperiodicity—in the solutions of the equations, which are recognizable as generalisations of the well-known Lorenz attractor equations. Equations describing the evolution of wave packets take a variety of forms; for vanishingly small dissipation or for large dissipation, they are essentially parabolic and of nonlinear Schrödinger type, whilst for moderate dissipation they are of Lorenz type, modified by spatial variations. Solutions of a number of these equations are discussed and compared, where appropriate, with experimental results.     

Recent developments and on-line tests of uranium carbide targets for production of nuclides far from stability

The capacity of uranium carbide target materials of different structure and density for production of neutron-rich and heavy neutron-deficient nuclides have been investigated. The yields of Cs and Fr produced by a 1 GeV proton beam of the PNPI synchrocyclotron and release properties of different targets have been measured. Yields and release efficiencies of Cs and Fr produced from a high density UC target material and from low density UCx prepared by the ISOLDE method at IRIS in the collaboration with PARRNe group from Orsay are compared. The yields from ISOLDE original target are presented for comparison as well.     

A Critical Phenomenon for Sublinear Elliptic Equations in Cone-Like Domains

The authors of this paper study positive supersolutions to theelliptic equation -u = c|x|^–su^p in Cone-like domains ofR^N (N 2), where p, s R and c > 0. They prove that in thesublinear case p < 1 there exists a critical exponent p_*> 1 such that the equation has a positive supersolution ifand only if – < p < p_*. The value of p_* is determinedexplicitly by s and the geometry of the cone. 2000 MathematicsSubject Classification 35J60 (primary), 35B05, 35R45 (secondary).     

Lifetimes of proton unstable states in 113I measured by the particle-X-ray coincidence technique

The -delayed proton decay of ¹¹³Xe was investigated by means of a total absorption -ray spectrometer and a telescope for particle detection. The energy window available for the -delayed proton decay of ¹¹³Xe and the relative branching ratios for proton transitions to the ¹¹²Te states were remeasured. The lifetimes of proton unstable ¹¹³I states populated in the electron capture decay of ¹¹³Xe were determined by means of the particle-X-ray coincidence technique. The results of the lifetime measurements are compared with statistical-model calculations.     

Electronic and chemical properties of nanostructured cerium dioxide doped with praseodymium

Nanostructured doped ceria is a prospective material for catalytic applications such as the construction of membranes with mixed electronic and ionic conductivity for effective syngas production. In this article, the surface properties of nanostructured ceria doped with praseodymium have been studied by X-ray photoelectron spectroscopy, secondary ion mass spectrometry, and Fourier transform infrared spectroscopy of adsorbed carbon monoxide. The effects of supporting 1.4 wt % Pt as well as structural changes upon the reduction of the samples with methane have been investigated. While in samples without supported platinum, mainly praseodymium cations are reduced in a methane atmosphere; stronger reduction of cerium cations was found in the case of surface modification with Pt. The structural differences correlate with results from temperature-programmed reaction experiments with methane. Explanations are discussed in terms of different reaction mechanisms.     

Baroclinic wave packets described by spatially varying Lorenz equations

Solutions are obtained numerically for the evolution in space and time of the amplitude of a baroclinic wave packet in a weakly viscous fluid. The behaviour observed is confirmed analytically to resemble that occuring for wave trains, described by the Lorenz attractor equations, at a modified value of the viscosity parameter.     

Novel summability methods generalizing the Borel method

The paper deals with moment constant summability methods. A method is constructed which provides an analytic continuation of a function regular at the origin onto its Mittag-Leffler (principal) star. In this sense the method is optimal in contrast to the Borel one. In the next a one parameter family of such methods is introduced. The methods may be useful both in field theory and in statistical physics. Applications to the Nevanlinna theorem, the Rayleigh-Schrö-dinger perturbation theory and the dispersion-like integral are given. The proofs of theorems can be easily adapted to the study of the Mellin transform of some entire functions and a simpler proof of asymptotic properties of the gamma function can be obtained.I am indebted to J. Fuka for stimulating discussions and J. Fischer for continuous interest in my work and valuable comments. Financial support of the Czech Literatury Fund is also gratefully acknowledged.     

NMR study of the structure of a polyhydrate-forming ion exchanger

Institute of Inorganic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 31, No. 3, pp. 39–43, May–June, 1990.     

Effect of prolonged storage on the mechanical properties of polycarbonates

The effect of storage time (two-four years) on the principal mechanical characteristics of domestic polycarbonate and West German Makrolon has been experimentally investigated.Moscow Lomonosov State University. Translated from Mekhanika Polimerov, No. 6, pp. 1130–1132, November–December, 1970.