Rimma M. Farzetdinova

Quasi-two-dimensional diluted magnetic semiconductors with arbitrary carrier degeneracy

In the framework of the generalized mean field theory, conditions for arising the ferromagnetic state in a two-dimensional diluted magnetic semiconductor and the features of that state are defined. RKKY-interaction of magnetic impurities is supposed. The spatial disorder of their arrangement and temperature alteration of the carrier degeneracy are taken into account.

Nonuniform RKKY Magnetism in Thin Films/Wires

Mean-field continual model of Ruderman-Kittel-Kasuya-Yosida (RKKY) magnetism in thin films and wires is considered. The spatial distribution of the magnetization is described by the nonlinear integral equation. The magnetization distribution over the film thickness or the wire diameter is close, correspondingly, to the parabolic or Gaussian one. The dependence of the Curie temperature on the film thickness, and temperature dependencies of the average film and wire magnetizations are determined.

Branching of electron current and quantum effects in two-dimensional dislocation barrier of n-type semiconductor

Abstract Electron current through the dislocation wall of the bicrystal boundary flows through saddle points of the 3D-potential relief. At low-enough temperatures this leads to current branching, i.e. to the separation of the current into numerous channels. Under some conditions, these channels make up 1D-conductors with the ballistic transport. As this takes place, effects associated with the quantum nature of the channel conductance could be observed experimentally.

Long- and Short-Term Memories as Distinct States of the Brain Neuronal Network

There are two types of memory – short-term and long-term ones. First, the former arises and then the latter one (in the course of the so called consolidation process). Own neuronal networks (engrams) in the brain correspond to each of those memories, and our goal is to understand what is the difference between those networks from viewpoint of their structural properties. It is not about the special biochemical structure of some neurons or synapses arising under the memory consolidation, but about some total topological properties of those brain networks which are associated with the stored pattern. In other words, could the topological reconstruction of the neuronal network promote the memory consolidation and transfer it into the long-term form? The model consideration of that phenomena shows that such a process is quite possible. For that to happen, two conditions have to be met: (i) the neuronal net should be, initially, the scale-free one, and (ii) the memory consolidation should proceed via the building of long-range links that arise at this stage, for instance, by means of new axon-neuron synaptic contacts.

Color or Luminance Contrast – What Is More Important for Vision?

In the framework of a simple analytical model, we quantitatively validate the statement that the “color world” is amenable to much more accurate and faster segmentation than the “gray world”. That results in significant facilitating conditions required for originating indispensable pop-out effect, and, probably, forms the basis of various cognitive phenomena connected with the color vision. Besides, we show that the known (from optics) Rayleigh criterion for separability of two gray objects is considerably softened for objects of different colors.

Multiple goal pursuit -- to kill two birds with one stone or to fall between two stools ?

We present the simple phenomenological (but - analytic) model allowing to formalize description of multitasking, i.e. simultaneous performing several tasks. That process requires distribution of attention, and for great number of goals do not lead to success. Our consideration shows that simultaneous performing more than two tasks is, most likely, impossible.

On Miller’s rule for the brain working memory, or why human memory is so short

Working memory is a cognitive construct that describes how information can be maintained in brain for a limited period of time, while concurrent processing is also performed. We present a simple model that accounts for working memory span and explains the origin of the cognitive Miller’s rule (Magical Number Seven).

General mean-field theory for mechanical hysteresis of network-like macromolecules.

In the framework of the mean‐field theory for the order parameter, which characterizes the degree of deviating the structure of a network‐like macromolecule from its natural state under the action of the external force, its mechanical hysteresis is considered. Elastic hysterical properties of a macromolecule are studied as a function of the applied force, temperature and some other parameters controlling the viscous‐elastic behavior of network‐like macromolecules. Proteins 2014; 82:3188–3193.

Ground state for lattices of nonspherical ferromagnetic granules with dipole-dipole magnetic interaction

Summary form only given. In the paper, magnetic phase diagrams of regular 2D- and 3D-lattices of ellipsoidal single-domain ferromagnetic granules with dipole-dipole interaction are studied. Relying on the approximate, though accurate enough, expression for the pair interaction of nonspherical granules derived by the authors, numerical calculations of the magnetic energy for the considered systems are performed. It has been shown that, unlike the lattice of point (or spherical) magnetic moments whose ground state is always antiferromagnetic or frustrated (for the triangle lattice), the ground state of 2D-lattices composed of nonspherical granules might be ferromagnetic.