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В статье представлена модель организации проекта консультационного центра для родителей, дети которых не посещают дошкольные образовательные учреждения. Описан опыт взаимодействия консультационного центра с родителями (законными представителями) детей дошкольного возраста, в том числе детей с ограниченными возможностями здоровья, посредством предоставления методической, диагностической, психолого-педагогической и консультационной помощи.

The high-frequency transport in a two-dimensional conducting ring having an inhomogeneous collinear magnetic structure has been considered in the hydrodynamic approximation. It is shown that the frequency dependence on the radial electric conductivity of the ring exhibits resonances corresponding to new hybrid oscillations in such systems. The oscillation frequencies are essentially dependent on the applied electromagnetic field and the spin state of the system.

It is shown that the normal electron–electron scattering is a source of electrical resistance on non-contact current excitation in two-dimensional spin–split electron systems. In contrast to the contact current injection, non-contact current excitation causes spatially inhomogeneous polarization in a two-dimensional conductor leading to new resistivity mechanisms.

Transport phenomena are examined in electron systems on liquid helium surfaces in strong nonquantizing nonuniform magnetic fields. For applied electric fields with frequencies low enough that an equilibrium distribution of the spins along the conducting surface can develop during the wave period, the electrical resistance is determined by different current carrier scattering processes than in the uniform case. Spin nonuniformity makes electron-electron collisions efficient with respect to momentum loss, so that galvanomagnetic effects differ substantially from the Drude-Lorentz theory. A nonstationary spin-electron effect is found in a direction perpendicular to the applied electric field. The evolution of the transport properties following application of a nonuniform magnetic field is discussed.

The dynamics of a nonequilibrium spin system dominated by collisions preserving the total quasimomentum of the interacting electrons and quasiparticles is considered. An analysis of the derived hydrodynamic equations shows that weakly attenuated spin-polarization waves associated with an oscillating drift current can exist in a magnetically inhomogeneous conducting ring. Spin-polarized transport in a ballistic regime of wave propagation through a conductor is also considered, and a simple method is proposed for distinguishing these waves from spin and current oscillations that develop in the hydrodynamic regime. It is shown that a potential difference arises between the leads of an open nonuniformly spin-polarized conductor as a manifestation of spin polarization of electron density. This spin-mediated electrical phenomenon occurs in both hydrodynamic and diffusive limits.

It is shown that a potential difference, the value of which depends on the spin state of electrons, appears in the vicinity of the system of electrons floating on the surface of liquid helium in an inhomogeneous magnetic field.

Experimentally electron-beam injection and detection via quantum point-contacts is used to investigate the scattering of a non-equilibrium electron distribution in a two-dimensional electron gas (2DEG) of a GaAs/(Ga,Al)As heterostructure. The energy dependence of electron–electron scattering processes has been studied in a weak magnetic field by investigating the detector signal. Assuming electron beams with a narrow opening angle a magnetic field B perpendicular to the 2DEG plane causes only electrons which are scattered in a point O at an angle α to reach the detector. Thus, it is possible to measure directly the energy dependence of the angular electron distribution after scattering. The experimental data give a clear evidence for the importance of small angle scattering processes in two-dimensional systems, as predicted theoretically.

Experimental studies of electron-beam propagation in a degenerate 2DEG in a GaAs-(Al,Ga)As heterostructure are presented for a wide range of injection energies, 0

The detailed quantitative theory of electron-electron scattering processes in 2D electron degenerated systems in GaAs(AlGaAs) heterostructures has been developed on the basis of analytical treatment and numerical calculations. We have found the conditions and intervals of values of the characteristic parameters in which specific properties of 2D relaxation predicted previously on the theoretical level manifest themselves. New effects, i.e. a secondary beam of electrons scattered back and a very narrow beam of holes moving in the direction of injection, have been found.

It is predicted that a spin signal can be converted into a change of the electric potential. This effect arises when spin-polarized electrons from a nonmagnetic circuit N penetrate into a magnetized magnetic attachment M with Zeeman splitting of the electron spectrum. Since M possesses a high density of spin states with the same direction of the spin, the penetration of spin-polarized electrons into M results in the appearance of an electric double layer at the N–M boundary and therefore a jump in the electric potential between M and N. The predicted effect can be used for direct detection of a spin signal in nonmagnetic metals and semiconductors as well as for solving a number of problems of spintronics because of the ease with which an electric field can be controlled by currents in semiconductors.

Spin injection from a ferromagnetic metal into a semiconductor driven by a constant phonon flow is considered. It is shown that diffusive (as opposed to electrical) spin injection gives rise to a highly spin-polarized current through the semiconductor. In other words, phonon-wind-driven injection under certain conditions eliminates the conductivity mismatch responsible for reduced spin polarization of the electric current injected from a ferromagnetic metal into a semiconductor.

The cost of reduced pellets is associated with the quality and productivity of the shaft furnaces, which, in turn, depend on the properties of the initial roasted pellets—their structure and the type of binder. Methods for enhancing the quality of the roasted pellets used in shaft reduction furnaces were discussed in [1‐5]. The most interesting are associated with increase in the softening temperature of the binder, the hot strength, and the reducing properties [6‐8]. This is also associated with increase in temperature in the reduction zone, which provides the basis for the introduction of a technology such as oxygen injection in the shaft furnaces. The HYL-III unit at OAO Lebedinskii GOK has some scope for increase in the reducing-gas temperature, but its utilization is not always possible. Thus, increasing the temperature in the reducing zone above 855 ° C usually disrupts batch descent and discharge of the reduced pellets, on account of pellet deformation. The prevention of such disruptions, which are undesirable and in some cases dangerous, is mainly associated with the properties of the oxidized pellets: first, their degree of oxidation (their FeO content), which is determined by the heat treatment of the batch layer on the conveyer-type roasting machine and significantly influences the reduction process; and, second, the structure of the pellets and their binder, which must be difficult to melt and to reduce. The degree of pellet oxidization determines the minimum deformation of the reduced pellets under load, while the structure of the pellet binder determines how great a role it will play in low-temperature softening of the iron oxides. The effectiveness of this approach was confirmed in the startup of the HYL-III unit in 2001, using pellets with added bauxite. However, with the existing composition of the pelletization batch, whose use has allowed the unit to exceed its design parameters, it is impossible to increase the temperature in the reducing zone above 845‐847 ° C, on account of the high plasticity of the reduced pellets. Therefore, increasing the productivity of the HYL-III unit by further temperature rise in the reducing zone calls for two approaches: modification of the pelletization-batch composition, which permits the formation of stronger and more refractory binder; and optimization of the heat-treatment conditions, so as to form such binder and increase pellet oxidation. In the present work, we investigate these approaches. The role of the rock composition in forming the metallurgical properties of the pellets was outlined in detail in [1, 6‐8]. It is found that an effective means of optimizing the structure and metallurgical properties of the pellets for blast-furnace smelting and reduction is to modify the batch with additives that increase the melting point of the binder and facilitate the formation of more open porosity. The existing binder, corresponding to the Fe 2 O 3 ‐Al 2 O 3 ‐CaO‐SiO 2 system, is created by introducing bauxite as an additive in palletizing the concentrate [6‐8]. Using bauxite increases not only the pellet strength on reduction but also the oxidation rate on roasting and the rate of reduction. To increase the strength of the pellets on reduction, their structure and the binder properties are further modified by means of magnesium-bearing additives, to form the CaO‐MgO‐SiO 2 and MgO‐Al 2 O 3 ‐SiO 2 systems. In laboratory research, the batch for pellet production is modified not with chalk but with Mg-bearing serpentinite‐magnesite, of the following chemical composition: 3.76% Fe tot ; 0.99% FeO; 4.28% Fe 2 O 3 , 27.5% SiO 2 , 0.42% Al 2 O 3 , 5.69% CaO, 32.38% MgO, 0.012% TiO 2 , 0.172% MnO, 0.008% S, 3.21% C, 0.018% P 2 O 5 , 0.004% K 2 O, 0.016% Na 2 O, 22.28% calcination losses. In the laboratory apparatus, to obtain the masstransfer characteristics, characteristics such as the rate constant of pellet reduction at 900 ° C and the strength of pellets partially (up to ~30%) reduced at this temperature are determined. The influence of the batch composition on the shrinkage, sintering properties, and degree

A mathematical method based on a reduced representation of the electron–electron collision operator acting in the space of quasi-equilibrium functions is constructed. A number of kinetic phenomena such as the evolution of highly anisotropic and high-energy electron distributions, the quasi-hydrodynamic effect in electrical conduction, and a new nonlinear transport mode are described from a unified point of view. Kinetic effects which can be observed in experiments on electron beam propagation and electrical conduction of (GaAs)Al wires with a high mobility of charge carriers are predicted.

A nanoelectromechanical device based on magnetic exchange forces and electron spin flips induced by a weak external magnetic field is suggested. It is shown that this device can operate as a new type of single-electron "shuttle" in the Coulomb blockade regime of electron transport.

Evolution of sharp angular distributions in the degenerate two-dimensional gas of colliding electrons has been shown to occur essentially otherwise than in the three-dimensional gas. As early as after a few collisions the electron distribution function becomes antisymmetric in momentum, conserving, practically, its sharpness. Further spreading of this distribution in coordinate and momentum spaces occurs rather slowly, taking much more time than an electron-electron collision. Application of an extremely weak magnetic field leads to essential changes in this picture. The possibility of observing new effects in experiments on electron beam evolution in heterostructures is discussed.

The role of electron–electron collisions in the formation of spin-polarized current states in a spin guide—a system consisting of a nonmagnetic conducting channel wrapped in a grounded nanoscale magnetic shell—is studied. It is shown that under certain conditions the spin guide can generate and transport nonequilibrium electron density with high spin polarization over long distances even though frequent electron–electron scattering causes drifting of the nonequilibrium electrons as a whole. Ways to convert the spin-polarized electron density into a spin-polarized electric current are proposed.

The influence of electron–electron scattering on the efficiency of certain methods for the injection and generation of spin–polarized current states in nonmagnetic conductors is discussed. We consider the effect of electron–electron collisions on the resistance to electric transport developing at the interface between a magnetic conductor (MC) and a nonmagnetic conductor (NMC). An essentially unbounded increase of the interfacial MC/NMC magnetoresistance with temperature is predicted.

A new method to study electron scattering processes in conductors is proposed and experimentally realized. This method is based on the separation of the particles which are scattered at the different angles in a magnetic field. Experimental implementation of this method on GaAs(AlGaAs) heterojunctions has confirmed the ideas about essential differences of momentum transfer mechanisms in two- and three-dimensional systems. Most conspicuous is the increased importance of the small angular scattering for small excess energies.

We investigate the diffusive electron transport in conductors with spatially inhomogeneous magnetic properties taking into account both impurity and normal scattering. It is found that the additional interface resistance that arises due to the magnetic inhomogeneity depends essentially on their spatial characteristics. The resistance is proportional to the spin flip time in the case when the magnetic properties of the conducting system vary smoothly enough along the sample. It can be used to direct experimental investigation of spin flip processes. In the opposite case, when magnetic characteristics are varied sharply, the additional resistance depends essentially on the difference of magnetic properties of the sides far from the interface region. The resistance increases as the frequency of the electron-electron scattering increases. We consider also two types of smooth interfaces: (i) between fully spin-polarized magnetics and usual magnetic (or non-magnetic) conductors, and (ii) between two fully oppositely polarized magnetic conductors. It is shown that the interface resistance is very sensitive to appearing of the fully spin-polarized state under the applied external field.

We propose spintronic systems which spin dynamics is determined by the frequent normal electron collisions. Spin oscillation induced by the electrical field is predicted. The hydrodynamic equations for the electron spin-polarized liquid have been obtained and analyzed. We found that in the case of a conducting magnetic-inhomogeneous ring, both the spin polarization and the drift current may oscillate simultaneously with a large decay time (``spin pendulum''). We demonstrate also that the spin polarization of the electron density may be revealed via the voltage between the ends of the open circuit with an inhomogeneous spin polarization. The effect may be observed both in the hydrodynamic and the diffusive regimes.

A method for the evaluation of the angular width of an electron beam generated by a nanoconstriction is proposed and demonstrated. The approach is based on analysis of a narrow-width electron flow that quantizes into modes inside a confining constriction, which is described in the adiabatic approximation, evolving into a freely propagating electronic state after exiting the constriction. The method that we developed allows us to find the parameters and the shape of the constriction that are optimal for generation of extremely narrow electron beams. In the case of a constriction characterized by a linear widening shape, an asymptotically exact solution for the injection problem is found. That solution verifies semiquantitative results related to the angular characteristics of the beam, and it opens the way for determination of the distribution function of the electrons in the beam. We have found the relationship between the angular distribution of the electron density in the beam and the quantum states of the electrons inside the constriction. Such narrow electron beams may be employed in investigations of electronic systems and in data manipulations in electronic and spintronic devices.

Evolution of sharp angular distributions in the degenerated two-dimensional electron gas of colliding electrons has been analysed. It is shown that the part of the electron distribution function which is odd in momentum smears considerably slower than the even one, and this is the reason of the unusual behavior of the propagation of two-dimensional electron beams.

A magnetic-field-effect transistor is proposed that generates a spin-polarized current and exhibits a giant negative magnetoresitance. The device consists of a nonmagnetic conducting channel (wire or strip) wrapped, or sandwiched, by a grounded magnetic shell. The process underlying the operation of the device is the withdrawal of one of the spin components from the channel, and its dissipation through the grounded boundaries of the magnetic shell, resulting in a spin-polarized current in the nonmagnetic channel. The device may generate an almost fully spin-polarized current, and a giant negative magnetoresistance effect is predicted., 4 pages, 3 figures

A theory is developed for the evolution of the non-equilibrium distribution of quasiparticles when the scattering rate decreases due to particle collisions. We propose a "modified one-collision approximation" which is most effective for high-energy quasiparticle distributions. This method is used to explain novel measurements of the non-monotonic energy dependence of the signal of scattered electrons in a 2D system. The observed effect is related to a crossover from the ballistic to the hydrodynamic regime of electron flow., Comment: 6 pages, 3 figures

Electron-beam propagation experiments have been used to determine the energy and angle dependence of electron-electron (ee) scattering a two-dimensional electron gas (2DEG) in a very direct manner by a new spectroscopy method. The experimental results are in good agreement with recent theories and provide direct evidence for the differences between ee-scattering in a 2DEG as compared with 3D systems. Most conspicuous is the increased importance of small-angle scattering in a 2D system, resulting in a reduced (but energy-dependent) broadening of the electron beam., Comment: 4 pages, 4 figures

The influence of electron–electron (e–e) scattering on the transport properties of a two-dimensional electron-gas in (Al ,Ga)As-GaAs heterostructures is studied experimentally and theoretically. The important role of e–e collisions has been demonstrated. Due to phase space restrains small-angle scattering events are expected to dominate the propagation of non-equilibrium electrons. The experimental evidence is given via injection-energy-dependent electron beam experiments.

The effects of spin polarization control in hybrid magnetic-nonmagnetic conductor structures have been considered. The concept of a transistor capable of generating and amplifying a spin-alternating signal has been proposed. The transistor principle is based on spatial separation of spin components and their control with electric gates in the “current-in-plane” hybrid magnetic-nonmagnetic conductor structure. This control is achieved through the effect of spin-electric signal transformation predicted in this study. Such transistor is feasible on the grounds of present-day materials and technologies.

In this work the scattering of a brief light pulse by a homogeneous spherical particle is studied within the framework of linear electrodynamics. Convenient formulas are obtained for the scattered fields of the pulse. As a concrete example the Rayleigh scattering of a light pulse is considered.

We have studied experimentally and theoretically the influence of electron-electron collisions on the propagation of electron beams in a two-dimensional electron gas for excess injection energies ranging from zero up to the Fermi energy. We find that the detector signal consists of quasiballistic electrons, which either have not undergone any electron-electron collisions or have only been scattered at small angles. Theoretically, the small-angle scattering exhibits distinct features that can be traced back to the reduced dimensionality of the electron system. A number of nonlinear effects, also related to the two-dimensional character of the system, are discussed. In the simplest situation, the heating of the electron gas by the high-energy part of the beam leads to a weakening of the signal of quasiballistic electrons and to the appearance of thermovoltage. This results in a nonmonotonic dependence of the detector signal on the intensity of the injected beam, as observed experimentally., Comment: 9 pages, 7 figures

A detailed theory of electron–electron scattering in two-dimensional degenerate systems in heterostructures is constructed as a result of analysis and numerical computations. The conditions are formulated and the values of characteristic parameters are obtained for which specific two-dimensional effects predicted earlier from theoretical considerations can be observed. New properties of scattering indicatrix, viz., a beam of electrons flying almost antiparallel to the primary beam and a very narrow beam of holes flying in the forward direction, are found.