Temperature dependence of the electron spin g factor in GaAs

The temperature dependence of the electron spin $g$ factor in GaAs is investigated experimentally and theoretically. Experimentally, the $g$ factor was measured using time-resolved Faraday rotation due to Larmor precession of electron spins in the temperature range between 4.5 K and 190 K. The experiment shows an almost linear increase of the $g$ value with the temperature. This result is in good agreement with other measurements based on photoluminescence quantum beats and time-resolved Kerr rotation up to room temperature. The experimental data are described theoretically taking into account a diminishing fundamental energy gap in GaAs due to lattice thermal dilatation and nonparabolicity of the conduction band calculated using a five-level kp model. At higher temperatures electrons populate higher Landau levels and the average $g$ factor is obtained from a summation over many levels. A very good description of the experimental data is obtained indicating that the observed increase of the spin $g$ factor with the temperature is predominantly due to band's nonparabolicity.Comment: 6 pages 4 figure

Optimal control of light pulse storage and retrieval

We demonstrate experimentally a procedure to obtain the maximum efficiency for the storage and retrieval of light pulses in atomic media. The procedure uses time reversal to obtain optimal input signal pulse-shapes. Experimental results in warm Rb vapor are in good agreement with theoretical predictions and demonstrate a substantial improvement of efficiency. This optimization procedure is applicable to a wide range of systems.Comment: 5 pages, 4 figure

Risk factors for the preservation of morphological changes in the gastric mucosa after eradication therapy for Helicobacter pylori infection in children with chronic gastritis

We conducted a clinical, morphofunctional examination and standard treatment of 155 children with chronic gastroduodenitis associated with Helicobacter pylori (HP) infection. It was кevealed that after 6 months lymphoplasmacytic infiltration of the gastric mucosa (GM) preserved in 37% of cases, and unspecified atrophy - in 9%, increased C3 and C4 components of the compliment - in 19% of children, antroduodenal discoordination on the background of postprandial secretin and cholecystokinin level - in 25%, as well as disorders of the intestinal microbiot

Position change strategies in the current global value chains: a micro-level aspect

The study includes an analysis of various levels of strategies for changing the positions of companies in the existing global value creation chains. First of all, companies in the technology sector of the economy in the Asian region, including companies of South Korea and China, have been considered. As the result of the research, some factors influencing the change in the subordinate position of companies in global value creation chains, -have been presented. In addition, the impact of these factors on changing positions of companies in the high-tech sector in global value creation chains has been analysed. The most frequently repeated factors have been structured and presented as a table

Influence of drying and pretreatment methods on certain parameters of yellow mealworm larvae (Tenebrio molitor)

Nowadays alternative protein sources like edible insects are becoming widely used as human food. One of the most popular insect is yellow mealworm (Tenebrio molitor) due to its high nutrition value. However, pretreatment and drying are necessary to increase the food shelf life and the efficiency of its use. Due to this, the purpose of the present work was the determination of influence of pretreatment methods (freezing of larvae for 1 month, freezing for 2 hours, freezing for 1 month followed by defrosting for 2 hours at room temperature, blanching) and drying methods (convection drying at 40 °C and 60 °C, microwave drying) of yellow mealworm on its color (determination of L*, а*, b*, ΔElab, Ch, H, BI), moisture content (gravimetric method), fatty acid composition (determined by gas chromatography with mass spectroscopy) and time of drying (time required to reach constant weight). It was found that all used pretreatment and drying methods had no effect on the fatty acid composition of the larvae. In terms of drying rate and color retention, microwave drying showed better results than convection drying at 40 °C and 60 °C. Meanwhile, convection drying at 40 °C leads to the higher final moisture content of the samples. Among the pretreatment methods, only blanching the larvae samples before drying retained their color better and also accelerated the rate of the convection drying

Morphometric study of hybridogenic species in Veronica subgenus Pseudolysimachium (Plantaginaceae)

We demonstrate the results of morphometric investigations of hybrids in Veronica subg. Pseudolysimachium (V. × altaica Kosachev und V. × kolyvanensis Kosachev et Shmakov) and their parents. Based on PCoA analysis with seven morphological characters, we reveal an intermediate position of the investigated hybrids and the most important taxonomic characters: ratio of length and width of the lamina of the upper leaves, height of plants, length of the longest corolla lobe and calyx lobe, presence of hairs on the calyx and their position, as well as the length of hairs on the internode below the inflorescence

Buffer-gas induced absorption resonances in Rb vapor

We observe transformation of the electromagnetically induced transparency (EIT) resonance into the absorption resonance in a $\Lambda$ interaction configuration in a cell filled with $^{87}$Rb and a buffer gas. This transformation occurs as a one-photon detuning of the coupling fields is varied from the atomic transition. No such absorption resonance is found in the absence of a buffer gas. The width of the absorption resonance is several times smaller than the width of the EIT resonance, and the changes of absorption near these resonances are about the same. Similar absorption resonances are detected in the Hanle configuration in a buffered cell.Comment: 11 pages, 15 figures; 13 pages, 17 figures, added numerical simulatio

Vacuum Squeezing in Atomic Media via Self-Rotation

When linearly polarized light propagates through a medium in which elliptically polarized light would undergo self-rotation, squeezed vacuum can appear in the orthogonal polarization. A simple relationship between self-rotation and the degree of vacuum squeezing is developed. Taking into account absorption, we find the optimum conditions for squeezing in any medium that can produce self-rotation. We then find analytic expressions for the amount of vacuum squeezing produced by an atomic vapor when light is near-resonant with a transition between various low-angular-momentum states. Finally, we consider a gas of multi-level Rb atoms, and analyze squeezing for light tuned near the D-lines under realistic conditions.Comment: 10 pages, 6 figures; Submitted to PR