Chaos and rectification of electromagnetic wave in a lateral semiconductor superlattice

We find the conditions for a rectification of electromagnetic wave in a lateral semiconductor superlattice with a high mobility of electrons. The rectification is assisted by a transition to a dissipative chaos at a very high mobility. We show that mechanism responsible for the rectification is a creation of warm electrons in the superlattice miniband caused by an interplay of the effects of nonlinearity and finite band width.Comment: 4 pages, 4 figures (2 color figs). Sufficient revision in comparison with version1: More explanations on physics of the effect are added. Removed from version1 material will be published elsewher

Fractional and unquantized dc voltage generation in THz-driven semiconductor superlattices

We consider the spontaneous creation of a dc voltage across a strongly coupled semiconductor superlattice subjected to THz radiation. We show that the dc voltage may be approximately proportional either to an integer or to a half- integer multiple of the frequency of the applied ac field, depending on the ratio of the characteristic scattering rates of conducting electrons. For the case of an ac field frequency less than the characteristic scattering rates, we demonstrate the generation of an unquantized dc voltage.Comment: 6 pages, 3 figures, RevTEX, EPSF. Revised version v3: corrected typo

The influence of Galactic aberration on precession parameters determined from VLBI observations

The influence of proper motions of sources due to Galactic aberration on precession models based on VLBI data is determined. Comparisons of the linear trends in the coordinates of the celestial pole obtained with and without taking into account Galactic aberration indicate that this effect can reach 20 $\mu$as per century, which is important for modern precession models. It is also shown that correcting for Galactic aberration influences the derived parameters of low-frequency nutation terms. It is therefore necessary to correct for Galactic aberration in the reduction of modern astrometric observations

ОЦЕНКА УСТОЙЧИВОСТИ ПРОИЗВОДСТВА ОВОЩЕЙ В ПРИВОЛЖСКОМ ФО

The sustainability of potato production in the Privolzhsky federal district was evaluated with the use of statistical methods. The effect of changes of yield and acreage on the production of the culture was evaluated. The stability of levels of dynamic series is estimated. The stability of production dynamics has been measured with the use of trend models. С использованием статистических методов проведена оценка устойчивости производства овощей. Оценено влияние изменения урожайности и посевных площадей на валовые сборы данной культуры. На основе расчета показателей вариации оценена устойчивость уровней ряда динамики. С использованием трендовых моделей оценена устойчивость динамики производства

Small-Size Resonant Photoacoustic Cell of Inclined Geometry for Gas Detection

A photoacoustic cell intended for laser detection of trace gases is represented. The cell is adapted so as to enhance the gas-detection performance and, simultaneously, to reduce the cell size. The cell design provides an efficient cancellation of the window background (a parasite response due to absorption of laser beam in the cell windows) and acoustic isolation from the environment for an acoustic resonance of the cell. The useful photoacoustic response from a detected gas, window background and noise are analyzed in demonstration experiments as functions of the modulation frequency for a prototype cell with the internal volume ~ 0.5 cm^3. The minimal detectable absorption for the prototype is estimated to be ~ 1.2 10^{-8} cm^{-1} W Hz^{-1/2}.Comment: 11 pages, 5 figure

Solitary wave solution to the generalized nonlinear Schrodinger equation for dispersive permittivity and permeability

We present a solitary wave solution of the generalized nonlinear Schrodinger equation for dispersive permittivity and permeability using a scaling transformation and coupled amplitude-phase formulation. We have considered the third-order dispersion effect (TOD) into our model and show that soliton shift may be suppressed in a negative index material by a judicious choice of the TOD and self-steepening parameter.Comment: 6 page

Regioselective alkylation of the lower rim of p-tert-butylthiacalix[4]arene with n-(p-nitrophenyl)-α-bromoacetamide

The preparation of partially substituted thiacalix[4]arenes 2-6 has been accomplished by conducting the reaction of the thiacalixarene 1 with N-(p-nitrophenyl)-α-bromoacetamide in acetone or acetonitrile in the presence of M2CO3 (M = Na, K and Cs). The influence of the reaction conditions (temperature, time, solvent, ratio of the reagents and the nature of the alkali metal carbonate) on regio- and stereoselectivity of this reaction is described. © 2009 Taylor & Francis

Nonlinear Localization in Metamaterials

Metamaterials, i.e., artificially structured ("synthetic") media comprising weakly coupled discrete elements, exhibit extraordinary properties and they hold a great promise for novel applications including super-resolution imaging, cloaking, hyperlensing, and optical transformation. Nonlinearity adds a new degree of freedom for metamaterial design that allows for tuneability and multistability, properties that may offer altogether new functionalities and electromagnetic characteristics. The combination of discreteness and nonlinearity may lead to intrinsic localization of the type of discrete breather in metallic, SQUID-based, and ${\cal PT}-$symmetric metamaterials. We review recent results demonstrating the generic appearance of breather excitations in these systems resulting from power-balance between intrinsic losses and input power, either by proper initialization or by purely dynamical procedures. Breather properties peculiar to each particular system are identified and discussed. Recent progress in the fabrication of low-loss, active and superconducting metamaterials, makes the experimental observation of breathers in principle possible with the proposed dynamical procedures.Comment: 19 pages, 14 figures, Invited (Review) Chapte

ОЦЕНКА УСТОЙЧИВОСТИ ПРОИЗВОДСТВА КАРТОФЕЛЯ В СТРАНАХ ЕВРОПЫ

The sustainability of potato production in the European countries was evaluated with the use of statistical methods. The effect of changes in yield and acreage on the production of the culture was evaluated. The stability of series levels was measured. The stability of production dynamics are measured with the use of trend models.С использованием статистических методов проведена оценка устойчивости производства картофеля в европейских странах. Оценено влияние изменения урожайности и посевных площадей на валовые сборы данной культуры. На основе расчета показателей вариации оценена устойчивость уровней ряда динамики. С использованием трендовых моделей оценена устойчивость динамики производства

АНАЛИЗ ОСНОВНЫХ ПОДХОДОВ К СНИЖЕНИЮ РИСКА ПРОИЗВОДСТВА В СЕЛЬСКОМ ХОЗЯЙСТВЕ

Agriculture is one of the most risky sectors of any economy. Modern science and practice have developed various methods to reduce the riskiness of production, such as avoiding the risk, hedging, diversification and insurance. In this article we discuss ways to reduce these risks of production.Любое производство подвержено риску. Не является исключением и сельское хозяйство. Современная наука и практика разработала различные методы снижения рискованности производства, например, такие как избежание риска, хеджирование, диверсификация, страхование. В статье рассматриваются именно эти способы снижения рисков производства