Polarization multistability of cavity polaritons

New effects of polarization multistability and polarization hysteresis in a coherently driven polariton system in a semiconductor microcavity are predicted and theoretically analyzed. The multistability arises due to polarization-dependent polariton-polariton interactions and can be revealed in polarization resolved photoluminescence experiments. The pumping power required to observe this effect is 4 orders of magnitude lower than the characteristic pumping power in conventional bistable optical systems.     

Experimental Study of the Dynamic Effect of an Internal Solitary Wave on a Submerged Circular Cylinder

The hydrodynamic loads due to the interaction of a small-amplitude internal solitary wave with a submerged circular cylinder in a two-layer system of miscible fluids were studied experimentally. The dependence of the internal-wave transmission coefficient on the position of the center of the cylinder relative to the pycnocline and on the ratio of the cylinder diameter to the fluid-layer thickness was obtained. The effects of the pycnocline thickness and the depth of the center of the cylinder on the value of the hydrodynamic loads were studied. Visualization of the flow structure was performed. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 6, pp. 36–44, November–December, 2005.     

Parametric optimization for a hyperbolic equation in divergence form with a pointwise state constraint: I

We consider an optimal control problem with a pointwise state constraint of inequality type and with dynamics described by a linear hyperbolic equation in divergence form with the homogeneous Dirichlet boundary condition. The state constraint contains a functional parameter that belongs to the class of continuous functions and occurs as an additive term. We study the properties of solutions of linear hyperbolic equations in divergence form with measures in the input data and compute the first variations of functionals on the basis of a so-called two-parameter needle variation of controls.     

Magnetic resonance of metallic nanoparticles in vitreous silicon dioxide implanted with iron ions

Silica glasses exposed to steady-state and pulsed irradiation with Fe⁺ ions are studied using magnetic resonance. The irradiation doses used in experiments are equal to 1 × 10¹⁵, 1 × 10¹⁶, and 1 × 10¹⁷ cm^?2. It is found that, under both steady-state and pulsed irradiation conditions, glass samples exposed at a dose of 1 × 10¹⁷ cm^?2 exhibit a broadband orientation-dependent signal. The shape of inclusions is evaluated under the assumption that the observed spectrum is caused by the ferromagnetic resonance induced in a new phase of metallic iron.     

Infrared absorption by polar optical phonons in a CdS nanocrystal array consisting of quantum dots and quantum wires

Based on the results of experimental studies, it is shown that, when the effect of size quantization on the vibratory properties of CdS nanocrystals is insignificant, the absorption spectra of nanocomposites containing CdS quantum wires and quantum dots exhibit not only the peak associated with the transverse optical phonons but also two other pronounced peaks associated with electrostatic vibration modes. When the size of nanocrystals is so small that the effect of size quantization cannot be neglected, the structure of the reflection and transmission spectra becomes much more complicated because of the contribution of the mixed longitudinal-transverse phonon modes.     

Integration ofD-dimensional cosmological models with two factor spaces by reduction to the generalized Emden-Fowler equation

The D-dimensional cosmological model on the manifold M=R×M₁×...×M_n, describing the evolution of Einstein factor spaces M_i in the presence of a multicomponent perfect fluid source, is considered. The barotropic equation of state for the mass-energy densities and pressures of the components is assumed in each space. Where the number of non-Ricci-flat factor spaces and the number of perfect fluid components are both equal to two, the Einstein equations for the model are reduced to the generalized Emden-Fowler (second-order ordinary differential) equation, which has been recently investigated by Zaitsev and Polyanin using discrete-group analysis. We generate new integrable cosmological models using the integrable classes of this equation and present the corresponding metrics. The method is demonstrated for the special model with Ricci-flat spaces M₁ and M₂ and a two-component perfect fluid source. Translated from Teoreticheskaya i Matematicheskaya Fizika. Vol. 114, No. 3, pp. 454–469, March, 1998.     

Application of tomography method in millimeter wavelengths band II. Experimental

Tomographycal methods of image reconstruction of two-dimensional objects, surfaces or subsurface regions in millimeter wavelengths band are suggested and considered. Experimental images obtained using antennas and waveguiding lines of different types and radiation frequencyf≈33÷35GHz are represented. Volumetric dielectric objects and plane-parallel ferrite (or dielectric) plates distributed in free space or in homogeneous dielectric medium have been taken as objects under investigation. It is shown that in the frequency band under consideration, the images of investigated objects with characteristic dimensionA≈2λ÷7λ may be obtained by first-order diffraction tomography method (Born, Rytov or high frequency approximation of the first-order for electromagnetic field).