Photon-meson transition form factors of light pseudoscalar mesons

The photon-meson transition form factors of light pseudoscalar mesons $\pi ^{0}$, $\eta$, and $\eta ^{\prime}$ are systematically calculated in a light-cone framework, which is applicable as a light-cone quark model at low $Q^{2}$ and is also physically in accordance with the light-cone pQCD approach at large $Q^{2}$. The calculated results agree with the available experimental data at high energy scale. We also predict the low $Q^{2}$ behaviors of the photon-meson transition form factors of $\pi ^{0}$, $\eta$ and $\eta ^{\prime }$, which are measurable in $e+A({Nucleus})\to e+A+M$ process via Primakoff effect at JLab and DESY.Comment: 22 Latex pages, 7 figures, Version to appear in PR

Оптимизация бизнес-процессов предприятия на основе методов бережливого производства

В данной работе рассматриваются способы оптимизации бизнес-процессов предприятия "Промышленная механика" на основе методов бережливого производства.Использование концепции бережливого производства позволяет оптимизировать бизнес-процессы при относительно невысоких затратах. Основные резервы в повышении эффективности организации лежат внутри самого бизнеса – а именно в области оптимизации бизнес-процессов.Данный подход не подразумевает коренных перестроек и изменений на производстве и в структуре руководства фирмы. А значит, что грамотно построенная система оптимизации предполагает достаточной автоматизацию одного из процессов, для повышения производительности на предприятии.This paper discusses ways to optimize the business processes of Industrial Mechanics based on lean manufacturing methods. Using the lean manufacturing concept allows you to optimize business processes at relatively low cost. The main reserves for improving the organization’s efficiency lie within the business itself - namely, in the field of optimizing business processes. This approach does not imply radical restructuring and changes in the production and in the structure of the company’s management. This means that a well-built optimization system requires sufficient automation of one of the processes to increase productivity in the enterprise

Effect of the length of inflation on angular TT and TE power spectra in power-law inflation

The effect of the length of inflation on the power spectra of scalar and tensor perturbations is estimated using the power-law inflation model with a scale factor of a(t) = t^q. Considering various pre-inflation models with radiation-dominated or scalar matter-dominated periods before inflation in combination with two matching conditions, the temperature angular power spectrum (TT) and temperature-polarization cross-power spectrum (TE) are calculated and a likelihood analysis is performed. It is shown that the discrepancies between the Wilkinson Microwave Anisotropy Probe (WMAP) data and the LCDM model, such as suppression of the spectrum at l = 2,3 and oscillatory behavior, may be explained by the finite length of inflation model if the length of inflation is near 60 e-folds and q > 300. The proposed models retain similar values of chi^2 to that achieved by the LCDM model with respect to fit to the WMAP data, but display different characteristics of the angular TE power spectra at l < 20.Comment: 41 pages, 11 figure

Quasiparticle properties of a coupled quantum wire electron-phonon system

We study leading-order many-body effects of longitudinal optical (LO) phonons on electronic properties of one-dimensional quantum wire systems. We calculate the quasiparticle properties of a weakly polar one dimensional electron gas in the presence of both electron-phonon and electron-electron interactions. The leading-order dynamical screening approximation (GW approximation) is used to obtain the electron self-energy, the quasiparticle spectral function, and the quasiparticle damping rate in our calculation by treating electrons and phonons on an equal footing. Our theory includes effects (within the random phase approximation) of Fermi statistics, Landau damping, plasmon-phonon mode coupling, phonon renormalization, dynamical screening, and impurity scattering. In general, electron-electron and electron-phonon many-body renormalization effects are found to be nonmultiplicative and nonadditive in our theoretical results for quasiparticle properties.Comment: 21 pages, Revtex, 12 figures enclose

Inelastic Coulomb scattering rates due to acoustic and optical plasmon modes in coupled quantum wires

We report a theoretical study on the inelastic Coulomb scattering rate of an injected electron in two coupled quantum wires in quasi-one-dimensional doped semiconductors. Two peaks appear in the scattering spectrum due to the optical and the acoustic plasmon scattering in the system. We find that the scattering rate due to the optical plasmon mode is similar to that in a single wire but the acoustic plasmon scattering depends crucially on its dispersion relation at small $q$. Furthermore, the effects of tunneling between the two wires are studied on the inelastic Coulomb scattering rate. We show that a weak tunneling can strongly affect the acoustic plasmon scattering.Comment: 6 Postscript figure

Tunneling effects on impurity spectral function in coupled asymmetric quantum wires

The impurity spectral function is studied in coupled double quantum wires at finite temperatures. Simple anisotropy in the confinement direction of the wires leads to finite non-diagonal elements of the impurity spectral function matrix. These non-diagonal elements are responsible for tunneling effects and result in pronounced extra peak in the impurity spectral function up to temperatures as high as 20 K.Comment: Accepted in Phys. Rev.

Electrochemical generation of catalytically active edge sites in c2n-type carbon materials for artificial nitrogen fixation

The electrochemical nitrogen reduction reaction (NRR) to ammonia (NH3) is a potentially carbon-neutral and decentralized supplement to the established Haber–Bosch process. Catalytic activation of the highly stable dinitrogen molecules remains a great challenge. Especially metal-free nitrogen-doped carbon catalysts do not often reach the desired selectivity and ammonia production rates due to their low concentration of NRR active sites and possible instability of heteroatoms under electrochemical potential, which can even contribute to false positive results. In this context, the electrochemical activation of nitrogen-doped carbon electrocatalysts is an attractive, but not yet established method to create NRR catalytic sites. Herein, a metal-free C2N material (HAT-700) is electrochemically etched prior to application in NRR to form active edge-sites originating from the removal of terminal nitrile groups. Resulting activated metal-free HAT-700-A shows remarkable catalytic activity in electrochemical nitrogen fixation with a maximum Faradaic efficiency of 11.4% and NH3 yield of 5.86 µg mg−1cat h−1. Experimental results and theoretical calculations are combined, and it is proposed that carbon radicals formed during activation together with adjacent pyridinic nitrogen atoms play a crucial role in nitrogen adsorption and activation. The results demonstrate the possibility to create catalytically active sites on purpose by etching labile functional groups prior to NRR