The 1H and 13C NMR chemical shifts of Strychnos alkaloids revisited at the DFT level

The density functional theory calculation of ¹H and ¹³C NMR chemical shifts in a series of ten 10 classically known Strychnos alkaloids with a strychnine skeleton was performed at the PBE0/pcSseg-2//pcseg-2 level. It was found that calculated ¹H and ¹³C NMR chemical shifts provided a markedly good correlation with experiment characterized by a mean absolute error of 0.08 ppm in the range of 7 ppm for protons and 1.67 ppm in the range of 150 ppm for carbons, so that a mean absolute percentage error was as small as ~1% in both cases.     

The conduction current in a metal-insulator-metal structure

The flow of the conduction current in a metal-insulator-metal structure under X-ray and optical excitation is considered. Accumulation of positive charge at the negative electrode in the KBr and CsI crystals is studied. The method of discharge currents after the X-ray and optical excitation is suggested for estimation of the near-surface charge. It is shown that the values of charge transported by the conduction current and those determined from the measured discharge-current signal are in satisfactory agreement. The lifetimes of near-surface charges of holes and anionic vacancies and the values of the electric-field strength at the metal-insulator interface are estimated. It is assumed that electroneutrality of the sample is established owing to the motion of electrons from the surface into the bulk over dislocations.     

Multinomial permutations on a circle

Multinomial permutations on a circle are considered in the framework of combinatorics. Different cases are presented and shown to agree with previously derived formula for the number of cyclic necklaces. Two applied examples are discussed with a view to illustrate the implications of derived formulas. Copyright © 2006 John Wiley & Sons, Ltd.     

Effects of trapped electrons on the line shape in emission Mössbauer spectra

To explain line broadening in emission Mössbauer spectra as compared to the corresponding absorber measurements, the model of trapped electrons has been proposed. Auger electrons (emitted, e.g. after electron capture by ⁵⁷Co or after the converted isomeric transition of ^119mSn), as well as secondary electrons, may be trapped in the proximity to the nucleogenic ion. Electrons captured by lattice traps at different distances from the daughter ion induce an asymmetric distribution of quadrupole splitting in the resulting emission spectra, as shown in a few examples. This model is supported by estimates of quadrupole splitting values which may be caused by such trapped electrons located at specified distances from the nucleogenic atom.     

The horocycle flow without minimal sets

We construct an example of a Fuchsian group such that the corresponding horocycle flow has no minimal sets. To cite this article: M. Kulikov, C. R. Acad. Sci. Paris, Ser. I 338 (2004).     

Super-Brownian motion with reflecting historical paths. II. Convergence of approximations

We prove that the sequence of finite reflecting branching Brownian motion forests defined by Burdzy and Le Gall ([1]) converges in probability to the “super-Brownian motion with reflecting historical paths.” This solves an open problem posed in [1], where only tightness was proved for the sequence of approximations. Several results on path behavior were proved in [1] for all subsequential limits–they obviously hold for the unique limit found in the present paper.Mathematics Subject Classification (2000): Primary 60H15, Secondary 35R60Supported in part by NSF Grant DMS-0071486, Israel Science Foundation Grants 12/98 and 116/01 - 10.0, and the U.S.-Israel Binational Science Foundation (grant No. 2000065).     

Prospects for triggering in experiment PAX at GSI

In experiment PAX, proposed for the new accelerator complex at GSI, investigations in the field of high-energy spin physics with the use of a polarized antiproton beam are planned. In this paper the possibilities for triggering are considered taking into account the PAX detector properties and a probable configuration of the trigger system is discussed for the first time. The text was submitted by the authors in English.     

Formation of coherent spatial structures in the reaction-diffusion atmospheric system under the action of a planetary wave

On the example of the effect of an atmospheric wave with given amplitude on the density oscillations of minor gas constituents near the mesopause (at heights 80–90 km, we consider the influence of the quasi-resonant periodic spatial transport on a distributed system responding subharmonically to a periodic external action (diurnal sunlight variations). Numerical modeling revealed the formation of a coherent horizontal distribution of the dynamical variables (i.e., the concentrations of small constituents). Application of this effect to the mesopause conditions is discussed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 47, No. 9, pp. 739–752, September, 2004.     

Gromov's K-area and symplectic rigidity

Supported by the United States-Israel Binational Science Foundation grant 94-00302