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Elemental status of a person determines the qualitative and quantitative content of chemical elements in the human body. This marker allows us to estimate the level of imbalance of chemical elements and therefore health risks. The method for simultaneous quantitative and qualitative analysis of 67 elements in biomaterials has been proposed. The detailed elemental analysis of whole blood samples of 1711 healthy people (age range 0-100 years) of Moscow Region has been performed. A number of patterns of age-related changes of the element status conditionally healthy people has been estimated. Na content in the samples increased with the age of the person. Presumably, this result reflects the studied populations nutrition disorders associated with immoderate consumption of table salt. The maximum content of Ca was observed in blood samples of people age range 0-20 years (66-69 mg/kg), the Ca content in the blood samples of people age range 26-85 years was significantly lower (59-62 mg/kg). The maximum decrease of Ca was detected in blood samples of people age range of 85-100 years (57-59 mg/kg). Thisreductionin the concentration of Ca, apparently due to age-related changes of Ca balance, correlates with decrease of bone mineral density and bone mass. Iron content decreased in the blood samples of people age range 10-100 years from 480 to 390 mg/kg. Selenium content in blood of people age range 0-25 years linearly increased, remained stable high in the blood of people age range 25-55 years (0,13-0,136 mg/kg) and then gradually decreased. A graph of As content dependence from a person's age is a mirror image of the graph of Se content dependence from a person's age, which is evidence of the antagonistic effects of these elements. Graphic changes in the content of rare earth elements Eu and Ho reflect the unidirectional trend of these elements accumulation. The maximum content of these elements was observed in blood samples of people age range of 25-65 years. Perhaps a reduction of Eu and Ho in the age range 65-100 years age reflects a downward trend in bone mineral density and decrease in bone mass, which correlates with the Ca content in the blood depending on the age of people. The data obtained showed a significant increase of U and V in the blood of people age range of 85-100 years. The compounds of vanadium and uranium normally relatively easily filtered by the kidneys and excreted in the urine. This result seems to demonstrate age-related deterioration in the functioning of the excretory system. A list of recommendations for nutrition correction of elemental imbalance of the observed population has been proposed.

Solutions of the parabolic equation which describes propagation of Bessel–Gaussian beams along the axis of an axially-symmetric medium having quadratic inhomogeneity have been obtained and investigated. It is shown that in the process of propagation the parameters of the beams change nonmonotonically. In the case of a transparent medium the beams periodically recover their initial structure.

In the paraxial optics approximation, we have studied the transformation of a simple Gaussian beam of light obliquely incident on an isotropic lens for the case where the axis of the beam and the principal optical axis of the lens are crossed straight lines. The data obtained are compared with the corresponding results for the case where the axes of the beam and lens are coplanar.

The problem of the passage of a Gaussian laser beam of light through a layer of gradient medium, whose dielectric permeability changes linearly in a direction approximately perpendicular to that of the propagation of the beam, is solved in the paraxial–optics approximation. The center of the beam in this medium propagates along a parabola, its divergence is independent of the parameter of the medium inhomogeneity, while the phase front remains approximately spherical.

Laser cavities with spherical mirrors and Gaussian diaphragms have been investigated. The influence of the parameters of mirrors and Gaussian diaphragms on the stability conditions of such cavities is shown.

The general properties of transforming the parameters of simple Gaussian beams by systems of centered lenses are investigated in the general case with arbitrary complex focal lengths. Analytical and graphic methods for solving the problems of this transformation are proposed.

The transformation of simple Gaussian light beams by lenses with a complex focal length is investigated in an approximation of paraxial optics. The results obtained are compared with the corresponding results of geometric optics into which they go over in limiting cases.

This paper discusses how temperature/pressure processing affects the cascade of magnetic phase transitions in the alloy Fe0.5Mn1.1As with a C38 tetragonal crystal lattice. It shows that after various temperature/pressure treatment regimes (quenching of the sample from 800 °C under pressures of 30–60 kbar) no transition to the low-temperature phase is observed, as a result of which the ferrimagnetic phase extends to liquid-nitrogen temperatures. These results are analyzed on the basis of a qualitative model that takes into account the competition of ferromagnetic and antiferromagnetic interactions within and between nonequivalent crystallographic subsystems.

Studies carried out using various methods — x-ray structural and spectral, electromagnetic, gravimetric, nuclear γ-resonance, and nuclear magnetic resonance — revealed that the crystal-chemical structure of mono-and polycrystalline manganese — zinc ferrites used in video tape recorders and color television sets possess defects, with various degrees of localization (point, plane, and cluster), existing simultaneously in both the cation and anion sublattices. Differences in the structure of mono- and polycrystalline specimens were observed, but the specimens were similar with respect to the nature of the clustered defects. A relationship between the defect structure and specified electromagnetic properties of the ferrites was established. It is concluded that more information is needed concerning the actual crystal-chemical structure of ferrites containing defects of different types and dimensions (micro, meso, macro).

We investigate the propagation, interaction and diffraction of electromagnetic waves in spatial structures, which are formed by intersecting planes directed at /spl pi//s angles (s - is the integer). We develop novel optical and optoelectronics elements on the basis of such spatial structures for transformation of polarization, energy, aperture, spectrum and others parameters of the wave beams.

The screen of type of infinitely thin semiplane is aligned with plane of dimensionless Decart system of co-ordinate. The diffraction of double-dimension (the dependence on z is absent) plane wave with the electricity vector E-polarization which is parallel to screen is considered. The Sommerfeld boundary conditions in the screen plane are given.

The surface modes of a plane symmetric dielectric waveguide with losses are investigated. It is shown that surface HE- (H-) modes do not have energy flux across the boundary, i.e., they are identical to guided modes. For EH- (E-) surface modes the energy flux across the boundary is small (quasiguided modes) in the case of weakly absorbing materials; guided EH- (E-) modes are quasisurface waves. A computational algorithm is proposed for obtaining the solutions.

An investigation is carried out in this paper of the structure of the radiation field of a laser with a resonator filled with an active medium whose inhomogeneity is modulated by a combination of a plane converter of waves (of the thin-lens type), which alters not only the phase but also the amplitude of a ray passing through it, and a homogeneous amplifying medium. The converter has a transmission coefficient with respect to the electric field of k~

A vector solution is obtained for the fields of the lowest-order modes in a three-layer elliptic fiber waveguide which is valid in the case of a small ellipticity of the boundaries between the layers, but is not restricted in respect of the differences between the refractive indices of the core and claddings. This solution is used to study mode birefringence as a function of the fiber waveguide parameters. It is shown that for a given core and an outer cladding, a waveguide with the W profile ensuring a high concentration of the energy of the lowest-order modes exhibits a stronger mode birefringence than a waveguide with a two-step profile. Near the limit of single-mode behavior an increase in the thickness of the inner cladding enhances the mode birefringence of a W-type waveguide, but reduces the corresponding birefringence of a two-step waveguide. The sensitivity of a three-layer waveguide to elliptic distortions of the boundaries increases on increase in the difference between the refractive indices of the three media forming the waveguide.

A vector solution is obtained for fields of fundamental modes of an elliptical three-layer optical fibre, which is valid for small ellipticity of boundaries between the layers and for arbitrary differences of core and cladding indices. The modal birefringence is investigated as a function of fibre parameters on the basis of this solution. It is shown that the two-step fibre birefringence is larger than the W-fibre birefringence for equal differences of the core and inner cladding indices. The relationship is inverse for equal differences of the core and outer cladding indices. The correlation between the birefringence value and the effective diameter of the single-mode fibre is discussed.

The starting point for understanding the processes of holographic writing and reading of information lies in the structure of the interference pattern arising in the detection medium when its surface is exposed to two (reference and object) plane (Fourier component) waves. Refracting at the surface of the crystal, each of them excites two waves, the ordinary and extraordinary, which propagate in different directions. These four waves, interfering among themselves, form a family of periodic spatial intensity lattices, the parameters of which also determine the basic properties of the hologram [i]. In the present work we study the structure of such lattices in a uniaxial crystal as a function of the parameters of the waves, the orientation of the optic axis, and the crystal anisotropy.

The spatial nonuniformity of a light beam, which carries optical information, causes a number of undesirable effects which worsen the quality of a holographic image: The relationship of the intensity and phases between the spectral-angular components of the object wave field is altered in the reconstruction, i.e., structural distortions arise, and new components appear which were absent in the recording (noise distortions). Theoretical investigations of these effects have been performed in many papers (see [1-3]); however, being based on generalizations of the Kogelnik theory of coupled waves [4], these investigations encompass only the case of volume (three-dimensional) holograms. For plane holograms a calculation of the intensity of distortions of the speckle-nonuniform object field has been carried out in [5]. Moreover, an intermediate case is often realized in practice in which the hologram is not plane but at the same time its thickness is still insufficiently large for one to treat it as a volume hologram. The effectiveness of the diffraction of light by such holograms has been calculated up to now on the basis of special numerical methods [6], and analytic methods have not even been developed for the plane-wave approximation. However, the numerical calculation performed in [6] has shown that the intensity of lower-order diffraction waves is described in the intermediate case by the Kogelnik formulas [4], which provides a basis for generalizing the theory of coupled waves to the case of holograms of arbitrary thickness with additional taking into account of higher-order diffraction beams.

The kinematic approximation is used in an investigation of the theoretical solution of the problem of diffraction of arbitrarily polarized light waves by static volume phase holograms in uniaxial crystals. The diffusion, drift in a field, and photogalvanic mechanisms of photorefraction are allowed for and no restrictions are imposed on the orientation of the optic axis of a crystal. Several special cases are considered for crystals of the symmetry classes 3m and 4mm when measurements of the intensity of the diffracted radiation can be used to estimate the contribution of the various mechanisms to the process of formation of a hologram and the conditions are established for the reconstruction of the polarization of an arbitrarily polarized object wave.

Mode birefringence of an elliptic fiber is described by a formula valid in the case of a small ellipticity of the core and an arbitrary difference between the refractive indices of the core and cladding. This formula is derived using approximate vector solutions of the Maxwell equations for two dominant orthogonally polarized modes. It is shown that there are considerable changes in the mode birefringence due to changes in the parameters of the single-mode regime. A study is made of the difference between the group velocities of the dominant modes. It is shown that the ranges of the parameters of a single-mode elliptic fiber in which the mode birefringence is maximal and the intermode dispersion minimal overlap near the limit of the singlemode regime. A comparison is made with the published results.

We investigate the frequency shift for phase-matched four-photon mixing processes in low mode-number GeO 2 -doped silica glass fibers as a function of dopant concentration, core radius, index profile and Nd:YAG laser pump wavelength for different mode combinations. The ways for the Stokes-anti-Stokes frequency tuning over wide visible and near-IR spectral region are presented.

An investigation was made of the frequency shift in stimulated four-photon processes involving various combinations of LP modes in fiber waveguides made of quartz glass. The dependence of the shift on the parameters of the waveguides, refractive index profile, and pump wavelength were determined. Propagation of the pump photons in various modes gave rise to a nonmonotonic dependence of the frequency shift on the core radius, but when the pump photons were carried by one mode, the frequency shift decreased on increase in the radius throughout the region where it varied and where phase locking was possible. A dip in the refractive index profile reduced considerably the frequency shift. The shift increased on increase in the pump wavelength and also on increase in the difference between the refractive indices of the core and cladding.