On the theory of acoustothermometry of waterlike media: Effects of the quasi-static field,strong absorption,and radiation pattern

An integral equation relating the thermal noise’s pressure measured by an acoustothermometer to the one-dimensional temperature profile of a waterlike medium is derived by applying the fluctuation-dissipative theorem to hydrodynamic equations. On the basis of this equation, effects of the quasi-stationary field of thermal radiation, a strong absorption of acoustic waves in the medium, and a finite beam width of the receiving antenna are investigated. Conditions under which the solution to the equation coincides with the result of the transfer theory, which ignores the aforementioned effects, are determined. The role of the effects under study in acoustothermometry of biological media is investigated. A method is proposed for controlling the depth from which the radiation is received. This method allows the retrieval of the temperature profile of the medium from the data of acoustic sounding.     

Resonant excitation of rossby waves in the equatorial waveguide and their nonlinear evolution

Nonlinear interactions between the baroclinic Rossby waves trapped in the equatorial waveguide and the barotropic Rossby waves freely propagating across the equator are studied within the two-layer model of the atmosphere, or the ocean. It is shown that a barotropic wave can resonantly excite a pair of baroclinic waves with amplitudes much greater than its proper amplitude. The envelopes of the baroclinic waves obey Ginzburg-Landau-type equations and exhibit nonlinear saturation and formation of characteristic "domain-wall" and "dark-soliton" defects.     

Shell models of magnetohydrodynamic turbulence

Shell models of hydrodynamic turbulence originated in the seventies. Their main aim was to describe the statistics of homogeneous and isotropic turbulence in spectral space, using a simple set of ordinary differential equations. In the eighties, shell models of magnetohydrodynamic (MHD) turbulence emerged based on the same principles as their hydrodynamic counter-part but also incorporating interactions between magnetic and velocity fields. In recent years, significant improvements have been made such as the inclusion of non-local interactions and appropriate definitions for helicities. Though shell models cannot account for the spatial complexity of MHD turbulence, their dynamics are not over simplified and do reflect those of real MHD turbulence including intermittency or chaotic reversals of large-scale modes. Furthermore, these models use realistic values for dimensionless parameters (high kinetic and magnetic Reynolds numbers, low or high magnetic Prandtl number) allowing extended inertial range and accurate dissipation rate. Using modern computers it is difficult to attain an inertial range of three decades with direct numerical simulations, whereas eight are possible using shell models.     

Synthesis of pyrimidinocyclophanes having a bridging nitrogen atom

Reactions of 1,3-bis(ω-bromoalkyl)-substituted uracils, quinazoline-2,4-dione, and 5-methyl-1,3,5-triazine-2,4,6-trione and 1,3-bis(m-bromomethylbenzyl)-5-bromouracil with amines (aliphatic amines, benzylamines, naphthylmethanamine, and anisidine) gave a series of macrocyclic compounds having one pyrimidine or triazine fragment and an azapolymethylene bridge connecting the N¹ and N³ atoms of the heteroring. The bridging nitrogen atom in some macrocyclic compounds was subjected to quaternization with methyl p-toluenesulfonate.     

Microwave impedance of a tunnel junction in the theory of a near-field microscope with atomic resolution

A theory is constructed for a near-field microwave microscope operating under tunneling breakdown between a probe and a conducting sample. Its informative characteristics are determined by the probe impedance, which is formed from the capacitive impedance Z _p of the near-field probe–sample interaction and tunnel junction impedance Z _t. A technique whereby the impedance Z _p is calculated using coaxial geometry of the probe is developed. Some properties of the impedance Z _t defined via the developed theory and published experimental data are investigated.