Proximity Action theory of superconductive nanostructures

We review a novel approach to the superconductive proximity effect in disordered normal-superconducting (N-S) structures. The method is based on the multicharge Keldysh action and is suitable for the treatment of interaction and fluctuation effects. As an application of the formalism, we study the subgap conductance and noise in two-dimensional N-S systems in the presence of the electron-electron interaction in the Cooper channel. It is shown that singular nature of the interaction correction at large scales leads to a nonmonotonuos temperature, voltage and magnetic field dependence of the Andreev conductance.Comment: RevTeX, 6 pages, 5 eps figures. This is a concise review of cond-mat/0008463; to be published in the Proceedings of the conference "Mesoscopic and strongly correlated electron systems" (Chernogolovka, Russia, July 2000

Practices of forest exploitation in priority investment projects: Benefits and implications

The paper discusses the topical issues of investment activities enhancement in the forest sector of the Russian economy by implementing the mechanism of priority investment projects in the field of forest exploitation - economic model of public-private partnership proposed by the forest owner (the State) for the private sector. The aim of the considered investment projects is the development of a timber-processing infrastructure, which is reliably provided with wood raw materials. It becomes possible to ensure certain preferences for businessmen that encourage them to invest money into the forest sector. Thus, the other objective is to develop recommendations for attracting investments into the forest sector of the Russian economy in the framework of priority investment projects. The paper analyzes a ten-year experience in the practice of applying priority investment projects in forest exploitation using an integrated approach to studying project management issues and method of comparison. The research identifies positive moments and a number of organizational and methodological shortcomings related to the development and implementation of investment projects in the forest sector of the Russian Federation. A number of areas contributing to the development of investment activities in forest exploitation is proposed. © Published under licence by IOP Publishing Ltd

Practices of forest exploitation in priority investment projects: Benefits and implications

The paper discusses the topical issues of investment activities enhancement in the forest sector of the Russian economy by implementing the mechanism of priority investment projects in the field of forest exploitation - economic model of public-private partnership proposed by the forest owner (the State) for the private sector. The aim of the considered investment projects is the development of a timber-processing infrastructure, which is reliably provided with wood raw materials. It becomes possible to ensure certain preferences for businessmen that encourage them to invest money into the forest sector. Thus, the other objective is to develop recommendations for attracting investments into the forest sector of the Russian economy in the framework of priority investment projects. The paper analyzes a ten-year experience in the practice of applying priority investment projects in forest exploitation using an integrated approach to studying project management issues and method of comparison. The research identifies positive moments and a number of organizational and methodological shortcomings related to the development and implementation of investment projects in the forest sector of the Russian Federation. A number of areas contributing to the development of investment activities in forest exploitation is proposed. © Published under licence by IOP Publishing Ltd

Random raman fiber laser based on a twin-core fiber with FBGs inscribed by femtosecond radiation

Narrowband Raman lasing in a polarization-maintaining two-core fiber (TCF) is demonstrated. Femtosecond point-by-point inscription of fiber Bragg gratings (FBGs) in individual cores produces a half-open cavity with random distributed feedback. The laser linewidth in the cavity with a single FBG inscribed in one core of the TCF reduced by ∼2 times with respect to the cavity with a fiber loop mirror. It is shown that the inscription of two FBGs in different cores leads to the formation of a Michelson-type interferometer, leading to the modulation of generation spectra near threshold. This technique offers new possibilities for spectral filtering or multi-wavelength generation

Dyson-Maleev representation of nonlinear sigma-models

For nonlinear sigma-models in the unitary symmetry class, the non-linear target space can be parameterized with cubic polynomials. This choice of coordinates has been known previously as the Dyson-Maleev parameterization for spin systems, and we show that it can be applied to a wide range of sigma-models. The practical use of this parameterization includes simplification of diagrammatic calculations (in perturbative methods) and of algebraic manipulations (in non-perturbative approaches). We illustrate the use and specific issues of the Dyson-Maleev parameterization with three examples: the Keldysh sigma-model for time-dependent random Hamiltonians, the supersymmetric sigma-model for random matrices, and the supersymmetric transfer-matrix technique for quasi-one-dimensional disordered wires. We demonstrate that nonlinear sigma-models of unitary-like symmetry classes C and B/D also admit the Dyson-Maleev parameterization.Comment: 16 pages, 1 figur