Characterization of the cleaved edge cross section of the heterostructures with GaMnAs layer by the confocal micro-Raman spectroscopy.

Confocal micro-Raman spectroscopy was used to measure cross-section linescans of the cleaved edge of heterostructures involving a GaMnAs layer. The investigations revealed a shift of the TO mode in the compressed GaMnAs layer to high frequencies relative to the TO GaAs mode in the substrate and to low frequencies in the tensile GaMnAs layers. These results are in agreement with the different manifestations of the anomalous Hall effect in the GaMnAs layers, with either compressive or tensile strains. It is shown that Raman spectroscopy is an appropriate method for the investigation of cross-sectional semiconductor heterostructures whose total thickness is comparable to the size of the analyzing laser spot.

Electromagnetic oscillations in a driven nonlinear resonator: a description of complex nonlinear dynamics.

Many intriguing properties of driven nonlinear resonators, including the appearance of chaos, are very important for understanding the universal features of nonlinear dynamical systems and can have great practical significance. We consider a cylindrical cavity resonator driven by an alternating voltage and filled with a nonlinear nondispersive medium. It is assumed that the medium lacks a center of inversion and the dependence of the electric displacement on the electric field can be approximated by an exponential function. We show that the Maxwell equations are integrated exactly in this case and the field components in the cavity are represented in terms of implicit functions of special form. The driven electromagnetic oscillations in the cavity are found to display very interesting temporal behavior and their Fourier spectra contain singular continuous components. This is a demonstration of the existence of a singular continuous (fractal) spectrum in an exactly integrable system.

Multiple scattering of electromagnetic waves by an array of parallel gyrotropic rods.

We study multiple scattering of electromagnetic waves by an array of parallel gyrotropic circular rods and show that such an array can exhibit fairly unusual scattering properties and provide, under certain conditions, a giant enhancement of the scattered field. Among the scattering patterns of such an array at its resonant frequencies, the most interesting is the distribution of the total field in the form of a perfect self-similar structure of chessboard type. The scattering characteristics of the array are found to be essentially determined by the resonant properties of its gyrotropic elements and cannot be realized for arrays of nongyrotropic rods. It is expected that the results obtained can lead to a wide variety of practical applications.

Exact solutions for the source-excited cylindrical electromagnetic waves in a nonlinear nondispersive medium.

The behavior of electromagnetic fields in nonlinear media has been a topical problem since the discovery of materials with a nonlinearity of electromagnetic properties. The problem of finding exact solutions for the source-excited nonlinear waves in curvilinear coordinates has been regarded as unsolvable for a long time. In this work, we present the first solution of this type for a cylindrically symmetric field excited by a pulsed current filament in a nondispersive medium that is simultaneously inhomogeneous and nonlinear. Assuming that the medium has a power-law permittivity profile in the linear regime and lacks a center of inversion, we derive an exact solution for the electromagnetic field excited by a current filament in such a medium and discuss the properties of this solution.

Exact axisymmetric solutions of the Maxwell equations in a nonlinear nondispersive medium.

The features of propagation of intense waves are of great interest for theory and experiment in electrodynamics and acoustics. The behavior of nonlinear waves in a bounded volume is of special importance and, at the same time, is an extremely complicated problem. It seems almost impossible to find a rigorous solution to such a problem even for any model of nonlinearity. We obtain the first exact solution of this type. We present a new method for deriving exact solutions of the Maxwell equations in a nonlinear medium without dispersion and give examples of the obtained solutions that describe propagation of cylindrical electromagnetic waves in a nonlinear nondispersive medium and free electromagnetic oscillations in a cylindrical cavity resonator filled with such a medium.

[Hospitalization for morbidity with respiratory diseases in residents of an industrial city]. / Gospitalizirovannaia zabolevaemost' po bolezniam organov dykhaniia naseleniia promyshlennogo goroda.

In view of the growth of adverse epidemiological indices for respiratory diseases (RD) in Russia, studies are warranted to get insights into regularities of their dynamics in a large industrial urban centre. A paradoxical decline is shown in the level of RD morbidity, caused by economical problems of health care with the growing need for hospitalization still in place, as exemplified by the situation in Orenburg. Of a serious concern to us is also an increasing latent RD morbidity resulting in disability of patients.

Trace elements in regulation of NF-kappaB activity.

In recent years several studies have shown that NF-kappaB might be a very important therapeutic target in the treatment ot various chronic inflammatory, degenerative and tumour diseases. Trace elements play essential roles in the regulation ot cell signaling mechanisms via transcription tactors and a large number of genes. An important aspect of the present review is the description ot the mechanisms by which trace elements might influence transcription factor NF-kappaB. DNA-binding activity of NF-kappaB is regulated by the redox state of the cysteine residue (Gys-62) in the DNA binding domain of the p50 subunit and impaired by different metals (Go, Cr, Ni, Cd, Pb). It has been hypothesised that the broad speciticity of interrelationships between NF-kappaB. AP-1 and various metals results from interactions of metals with specific moieties of transcription factors and IkappaB-kinases, as well as trom the existence of a metal-governed redox system. The hypothetical targets in the NF-kappaB signaling pathway affected by metals are: IkappaB-kinases, IkappaBs, NF-kappaB, proteasome degradation of NF-kappaB, kappaB-sites in DNA. Possibly, this system is required by the cell for adequate regulation ot the transcription machinery in response to changes in intracellular and intranuclear fluxes of metals and radicals and is very ancient evolutionary mechanism of stress adaptation. The role of the NF-kappaB-mediated mechanism in induction or prevention of chronic intlammatory, allergic, degenerative and tumor diseases by zinc, vanadium, manganese, copper, silica, iodine and other trace elements is discussed.

[General pathology of trace element deficiency]. / Obshchaia patologiia gipomikroélementozov.

According to the authors' concept, different forms of trace element deficiency show some general rules of development. All of them are followed by a decrease of immune resistance. Trace element deficiency is never isolated, it is always characterized by trace element unbalance and is followed by a considerable disturbance of metabolism (mineral, lipid, carbohydrate and protein) with relevant manifestations. Reduced immune resistance and pluriglandular endocrinopathy create the conditions for various malignancies.

[Trace elements and natural killer activity]. / Mikroélementy i estestvennaia killernaia aktivnost'.

Each cell of human body contains from 10(5) to 10(6) ions of different trace elements which may perform the important functions of regulation of cell metabolic system activity, genomic apparatus. However, the problem of trace elements influence on immune response, cytokine system, expression of components of the major histocompatibility complex and natural killer (NK) activity is not well studied. Some trace elements (Li, Zn, Mg, Se, Ge, Fe, etc.) show their effect on the level of intracellular messenger systems, inducing the production and potentiating the action of the great number of cell cytokines stimulating NK. Immune cytokines provide efficiency of NK-lysis and promote the decrease of tumor cell resistance to it. Interactions of trace elements and antitumor immunity is a perspective field of investigation.