Terahertz Bloch oscillator with a modulated bias

Electrons performing Bloch oscillations in an energy band of a dc-biased superlattice in the presence of weak dissipation can potentially generate THz fields at room temperature. The realization of such Bloch oscillator is a long-standing problem due to the instability of a homogeneous electric field in conditions of negative differential conductivity. We establish the theoretical feasibility of stable THz gain in a long superlattice device in which the bias is quasistatically modulated by microwave fields. The modulation waveforms must have at least two harmonics in their spectra.Comment: 5 page

Suppressed absolute negative conductance and generation of high-frequency radiation in semiconductor superlattices

We show that space-charge instabilities (electric field domains) in semiconductor superlattices are the attribute of absolute negative conductance induced by small constant and large alternating electric fields. We propose the efficient method for suppression of this destructive phenomenon in order to obtain a generation at microwave and THz frequencies in devices operating at room temperature. We theoretically proved that an unbiased superlattice with a moderate doping subjected to a microwave pump field provides a strong gain at third, fifth, seventh, etc. harmonics of the pump frequency in the conditions of suppressed domains.Comment: 8 pages. Development of cond-mat/0503216 . Version 2: Final version, erratum is include

Effect of biocorrective supplements on functional and technological properties of complex food systems

The article presents the results of studies on the effect of a bio-correcting food supplement on functional and technological properties of model liver-based pate systems. The supplement included components that are domestic resource-saving sources with predictable biopotential and consumer properties. The food-fortifying supplement was added to the model pate systems in the amount of 10–30%. The aim of the research is to study the effect of bio-correcting supplement on functional and technological properties of liver pate products. Technology of preparing model minced meat systems, along with traditional operations, included the stage of introducing a bio-correcting supplement into the cutter. It has been found that dry supplement components must be hydrated when used in the composition of pate recipes. The process of hydration of the enriching supplement was carried out with drinking water in the ratio of 1:2, and was stirred to a homogeneous state, then kept at the temperature of 19 ± 5°C for 10–15 minutes. That corresponded to the state of saturation of the system biopolymers with moisture and achievement of a pasty consistency, similar to that of pate masses. In the course of the research it was found that the model compositions had higher indicators of functional and technological properties compared with the control ones. The enriching additive in the composition of liver pate increased up to 30% compared with the samples prepared according to the traditional recipe: the moisture-binding capacity by 11–20%, the water-holding capacity by 20–25%, and the emulsifying capacity by 9–14%. The results obtained indicate the possibility of a targeted influence of the additive components on the functional and technological properties of liver pate. When a bio-correcting additive is included in liver pates, the pates get enriched with high-grade protein, vitamins, minerals and essential substances; organoleptic properties of finished products improve; calorie content of products reduces; functional, technological, structural and mechanical properties improve; the risk of broth-fat edema and moisture release from food products reduces; thermal losses decrease and the yield of finished products increases; a new product line of pates with high biopotential and consumer properties is obtained

GPR surveys and RPA aerial photography using in conducting geocryological studies on the Oka plateau in the Eastern Sayan ridge

The results of ground-penetrating radar (GPR) studies of permafrost and aerial photography, carried out at key sites in the Sentsa River valley (Oka Plateau, Eastern Sayan Ridge), are presented.For geophysical studies, an OKO-2 GPR completed with an AB-90 shielded antenna unit was used with a maximum sounding depth of up to 20 m and a resolution of 0.5 m. To account for the landscape elevation, the Trimble TS635 tacheometer and the Leiсa DISTO D 510 rangefinder performed hypsometric measurements with a step of 1.0 m. Aerial photography was carried out by a remotely piloted aircraft (RPA) DJI Inspire 1 Pro, equipped with a Zenmuse 3X camera (a resolution of 3840×2160 pixels) with a spatial resolution of 5.7–7.8 cm/pixel (in different years).In the structure of frozen lacustrine-alluvial sediments, three GPR complexes are distinguished, corresponding to the active layer and frozen rocks with different amounts of schlieren, lenses and layers of texture-forming ice. The orthophoto map and tacheometric survey analysis showed that the destruction of frost mounds occurs from the second half of April to the first half of October. The most significant relief change is due to the thawing of icy pulverescent clayey silts. It leads to subsidence blocks in the ledge of the Sentsa River terrace. Lateral river thermoerosion also contributes to the frost mounds destruction

Quantum squeezing of optical dissipative structures

We show that any optical dissipative structure supported by degenerate optical parametric oscillators contains a special transverse mode that is free from quantum fluctuations when measured in a balanced homodyne detection experiment. The phenomenon is not critical as it is independent of the system parameters and, in particular, of the existence of bifurcations. This result is a consequence of the spatial symmetry breaking introduced by the dissipative structure. Effects that could degrade the squeezing level are considered.Comment: 4 pages and a half, 1 fugure. Version to appear in Europhysics Letter

Multistable Pulse-like Solutions in a Parametrically Driven Ginzburg-Landau Equation

It is well known that pulse-like solutions of the cubic complex Ginzburg-Landau equation are unstable but can be stabilised by the addition of quintic terms. In this paper we explore an alternative mechanism where the role of the stabilising agent is played by the parametric driver. Our analysis is based on the numerical continuation of solutions in one of the parameters of the Ginzburg-Landau equation (the diffusion coefficient $c$), starting from the nonlinear Schr\"odinger limit (for which $c=0$). The continuation generates, recursively, a sequence of coexisting stable solutions with increasing number of humps. The sequence "converges" to a long pulse which can be interpreted as a bound state of two fronts with opposite polarities.Comment: 13 pages, 6 figures; to appear in PR