Approaches to the construction of simulation model of the process optimization of rare plants microclonal propagation

The authors present approaches to constructing an imitation model for the optimization of the process of rare plants microclonal reproduction (on the example of the Belgorod region), which allow to identify the most effective ways of explants sterilization, to define the optimal composition of nutrient media for regenerants growth (tube plants) and growth regulators (phytohormones) for propagation of mini-plant

Low-temperature scanning tunneling microscopy of ring-like surface electronic structures around Co islands on InAs(110) surfaces

We report on the experimental observation by scanning tunneling microscopy at low temperature of ring-like features that appear around Co metal clusters deposited on a clean (110) oriented surface of cleaved p-type InAs crystals. These features are visible in spectroscopic images within a certain range of negative tunneling bias voltages due to the presence of a negative differential conductance in the current-voltage dependence. A theoretical model is introduced, which takes into account non-equilibrium effects in the small tunneling junction area. In the framework of this model the appearance of the ring-like features is explained in terms of interference effects between electrons tunneling directly and indirectly (via a Co island) between the tip and the InAs surface.Comment: 8 pages, 4 figure

Scanning tunneling microscopy and spectroscopy at low temperatures of the (110) surface of Te doped GaAs single crystals

We have performed voltage dependent imaging and spatially resolved spectroscopy on the (110) surface of Te doped GaAs single crystals with a low temperature scanning tunneling microscope (STM). A large fraction of the observed defects are identified as Te dopant atoms which can be observed down to the fifth subsurface layer. For negative sample voltages, the dopant atoms are surrounded by Friedel charge density oscillations. Spatially resolved spectroscopy above the dopant atoms and above defect free areas of the GaAs (110) surface reveals the presence of conductance peaks inside the semiconductor band gap. The appearance of the peaks can be linked to charges residing on states which are localized within the tunnel junction area. We show that these localized states can be present on the doped GaAs surface as well as at the STM tip apex.Comment: 8 pages, 8 figures, accepted for publication in PR

Correlation induced switching of local spatial charge distribution in two-level system

We present theoretical investigation of spatial charge distribution in the two-level system with strong Coulomb correlations by means of Heisenberg equations analysis for localized states total electron filling numbers taking into account pair correlations of local electron density. It was found that tunneling current through nanometer scale structure with strongly coupled localized states causes Coulomb correlations induced spatial redistribution of localized charges. Conditions for inverse occupation of two-level system in particular range of applied bias caused by Coulomb correlations have been revealed. We also discuss possibility of charge manipulation in the proposed system.Comment: 6 pages, 4 figures Submitted to JETP Letter

Real roots of Random Polynomials: Universality close to accumulation points

We identify the scaling region of a width O(n^{-1}) in the vicinity of the accumulation points $t=\pm 1$ of the real roots of a random Kac-like polynomial of large degree n. We argue that the density of the real roots in this region tends to a universal form shared by all polynomials with independent, identically distributed coefficients c_i, as long as the second moment \sigma=E(c_i^2) is finite. In particular, we reveal a gradual (in contrast to the previously reported abrupt) and quite nontrivial suppression of the number of real roots for coefficients with a nonzero mean value \mu_n = E(c_i) scaled as \mu_n\sim n^{-1/2}.Comment: Some minor mistakes that crept through into publication have been removed. 10 pages, 12 eps figures. This version contains all updates, clearer pictures and some more thorough explanation

Basic principles of postgrowth annealing of CdTe:Cl ingot to obtain semi-insulating crystals

The process of annealing of a CdTe:Cl ingot during its cooling after growth was studied. The annealing was performed in two stages: a high-temperature stage, with an approximate equality of chlorine and cadmium vacancy concentrations established at the thermodynamic equilibrium between the crystal and vapors of volatile components, and a low-temperature stage, with charged defects interacting to form neutral associations. The chlorine concentrations necessary to obtain semi-insulating crystals were determined for various ingot cooling rates in the high temperature stage. The dependence of the chlorine concentration [Cl+Te] in the ingot on the temperature of annealing in the high-temperature stage was found. The carrier lifetimes and drift mobilities were obtained in relation to the temperature and cadmium vapor pressure in the postgrowth annealing of the ingot.Comment: 6 pages, 6 figure

Coulomb correlations effects on localized charge relaxation in the coupled quantum dots

We analyzed localized charge time evolution in the system of two interacting quantum dots (QD) (artificial molecule) coupled with the continuous spectrum states. We demonstrated that Coulomb interaction modifies relaxation rates and is responsible for non-monotonic time evolution of the localized charge. We suggested new mechanism of this non-monotonic charge time evolution connected with charge redistribution between different relaxation channels in each QD.Comment: 10 pages, 10 figure

СЕТЕВЫЕ МОДЕЛИ УПРАВЛЕНИЯ РИСКАМИ

The article contains multiple criteria model developed on the basis of analytic networks method(ANM) and the description of this intelligent system for risk management, developed on its basis.ANM can be used to solve a wide range of decision-making tasks. It allows working with difficultly formalizable, multicriteria problems with mutual influence of criteria and alternatives. ANM is the development of a method of hierarchies’ analysis and provides estimates of priority of all elements of network structure with respect to the intended target in the presence of mutual influences and feedbacks.Intelligent system, developed on the basis of the method of analytic networks includes a database, a set of procedures for processing expert preferences, as well as block of methods of statistical analysis for extracting knowledge. Knowledge in the system is used to solve problems of forecasting, to identify the relationship between criteria and other elements of the problem,as well as expert judgments to check for consistency.The example under consideration shows analytical multicriteria risk assessment model related to output of different kinds of artificial fiber for products used in transport industry.В статье представлены многокритериальная модель, разработанная на основе метода аналитических сетей (МАС), и интеллектуальная система управления рисками. МАС является развитием метода анализа иерархий и позволяет получить оценки приоритетности всех элементов сетевой структуры относительно заданной цели при наличии взаимных влияний и обратных связей. Интеллектуальная система включает базу данных, широкий набор процедур обработки экспертных предпочтений, а также блок статистического анализа данных, предназначенный для извлечения знаний. Знания используются для решения задач прогнозирования, выявления взаимоотношений между критериями и другими элементами задачи, проверки экспертных суждений на непротиворечивость. В рассматриваемом примере показана аналитическая многокритериальная модель оценки риска в процессе выпуска различных видов искусственного волокна для транспортной отрасли

Charge and spin configurations in the coupled quantum dots with Coulomb correlations induced by tunneling current

We investigated the peculiarities of non-equilibrium charge states and spin configurations in the system of two strongly coupled quantum dots (QDs) weakly connected to the electrodes in the presence of Coulomb correlations. We analyzed the modification of non-equilibrium charge states and different spin configurations of the system in a wide range of applied bias voltage and revealed well pronounced ranges of system parameters where negative tunneling conductivity appears due to the Coulomb correlations.Comment: 10 pages, 6 figure

Current status of turbulent dynamo theory: From large-scale to small-scale dynamos

Several recent advances in turbulent dynamo theory are reviewed. High resolution simulations of small-scale and large-scale dynamo action in periodic domains are compared with each other and contrasted with similar results at low magnetic Prandtl numbers. It is argued that all the different cases show similarities at intermediate length scales. On the other hand, in the presence of helicity of the turbulence, power develops on large scales, which is not present in non-helical small-scale turbulent dynamos. At small length scales, differences occur in connection with the dissipation cutoff scales associated with the respective value of the magnetic Prandtl number. These differences are found to be independent of whether or not there is large-scale dynamo action. However, large-scale dynamos in homogeneous systems are shown to suffer from resistive slow-down even at intermediate length scales. The results from simulations are connected to mean field theory and its applications. Recent work on helicity fluxes to alleviate large-scale dynamo quenching, shear dynamos, nonlocal effects and magnetic structures from strong density stratification are highlighted. Several insights which arise from analytic considerations of small-scale dynamos are discussed.Comment: 36 pages, 11 figures, Spa. Sci. Rev., submitted to the special issue "Magnetism in the Universe" (ed. A. Balogh