Vol 73, No 4 (2018)

The integrated cross sections of the ep → eπ⁺n, ep → eπ⁰p, ep → eK⁺Λ, and ep → eK⁺Σ⁰ reactions are evaluated in the energy range of nucleon resonance excitation at photon virtualities Q² from 5 to 12 GeV². These exclusive channels will be explored at photon virtualities Q² > 5 GeV² for the first time in future experiments with the CLAS12 detector. The cross-section evaluation is based on the extrapolation of exclusive contributions to the inclusive structure functions F₁ and F₂ from a region of Q² < 5 GeV², in which the experimental data are available, to the region of higher Q². This evaluation of cross sections is of particular importance in the development of the program of experiments with the CLAS12 detector for studying the structure of the ground and excited nucleon states, which may reveal the dynamics of strong interactions in the nonperturbative regime.

The theoretical bases of the so-called “pilot-wave” concept interpretation of quantum mechanics, as well as the performed and possible experiments to test its adequacy are considered.

Generation of X-ray radiation in a cascade self-amplified spontaneous emission free-electron laser (SASE FEL) using the harmonics of a two-frequency undulator is studied. The advanced phenomenological model of a one-pass FEL that accounts for the main losses in real FELs is presented: the electron energy spread in the beam, the beam divergence, diffraction, and the fact that emission losses are greater at higher harmonics than in the main frequency range. The FEL mathematical model was performed using the Mathematica software and calibrated within the experiment carried out at the operating SPARC facility via complex three-dimensional numerical simulations. The phenomenological model is used to analyze FEL dynamics for generation of a high-energy X-ray emission at a relatively short length. It is proposed to use a two-frequency undulator for the initial electron grouping and subsequent frequency multiplication in a cascade FEL with higher harmonic amplification (HGHG). The advantages of the two-frequency undulator are presented for electron grouping at higher harmonics of the undulator radiation (UR). The operation of several types of FEL is simulated with amplification of the seed laser wave frequency in two and three cascades to generate the soft X-ray radiation. A seed laser with a wavelength of 11.43 nm corresponding to the peak reflectivity of mirror coatings with MoRu/Be is proposed for generating the intensive X-ray laser radiation with λ ~ 1.27–3.37 nm. Here, the intensive radiation power reaches 50 MW at a length of only 35 meters; the radiation shows good temporal coherence corresponding to the performance of a low-power seed laser with a lower frequency.

Absorption and fluorescence spectra for living cells of green sulfur bacteria inhabiting the anaerobic zone of two meromictic lakes separated from the White Sea have been studied. The spectral-optical properties of pure cultures of green-colored and brown-colored species of green sulfur bacteria Chlorobium phaeovibrioides have been compared, and the content of bacteriochlorophyll molecules in one bacterial cell of each species has been estimated. The method of separating the contributions of different groups of green sulfuric bacteria to bacteriochlorophyll fluorescence was applied for a mixture of two species of bacteria with different pigmentation. The depth distributions of fluorescence intensity and concentration of bacteriochlorophylls for microorganisms inhabiting the Trekhtzvetnoe and Elovoe lakes at the Kandalaksha Gulf of the White Sea were plotted.

In this work, the concentration dependences of IR spectra were studied for aqueous LiCl, NaCl, RbCl, and CsCl solutions within the range from 4 to 0.2 M and an aqueous KCl solution within the range from 3 to 0.2 M at a temperature of –3.5°C in the middle IR region. The wavenumbers of the absorption band maxima were determined for stretching (ν₁, ν₃), combined (ν₂ + ν_L), and bending ν₂ vibrations at these concentrations. The established trends of the shift in the considered absorption bands provided a basis to make several conclusions about the structural transformations of the studied solutions with a decrease in concentration within the studied range. The calculations demonstrated an increase in the energy of hydrogen bonds between water molecules and their reduction in length with decreasing concentration for all of the studied solutions.

In this paper, the antiferromagnetic Ising model with ferromagnetic long-range interaction is modeled by the Monte Carlo method. The case of ferromagnetic long-range forces decreasing by a power law is considered. The dependence of the phase-transition temperature on long-range interaction parameters is obtained. The phase diagram was constructed at different values of long-range interaction parameters. Conditions for the existence of the frustrated state of the system were revealed.

The pharmacokinetics of the Astatine-211 radiopharmaceutical was investigated after a single injection in male SD (Sprague–Dawley) rats that had normal and iodine-free diets. Twelve groups of SD male rats were examined in the study. The tested drug was intravenously injected into the tail vein of the animals once at a volume of 10 mL/kg and dose of 100 μCi per animal. In the study, the animals were subjected to necropsy at specific time points with retrieval of the organs and tissues for further analysis of the activity of the samples using a well-type scintillation gamma spectrometer. It was found that the ²¹¹At absorption by the thyroid in the male rats that had an iodine-free diet was greater than in the rats that had a conventional diet.

We study Chaplygin gas as a candidate for inflation in the context of braneworld inflationary model. We investigate this model in the framework of the Randall–Sundrum type II, considering a original and generalized Chaplygin gas. We use inverse power law potential to examine the behavior of some inflationary spectrum parameters such as the spectral index n_s, the ratio r and the running of the scalar spectral index dn_s/dlnk, our results are in agreement with recent observational data for a particular choice of e-folding number N and parameters space of the model.

The results of sea level estimation by GNSS reflectometry (GNSS-R) in the Black Sea in the experiments at the stationary oceanographic platform are presented. The influence of the layout of the antennas and the characteristics of the wind waves on the GNSS-R sea level estimates is studied with the use of multi-antenna GPS/GLONASS receiver and wire resistance wave gauge. For the selected geometry of the experiment, the threshold amplitudes and frequencies of the wind waves at which estimation of the sea level by GNSS reflectometry becomes impossible are determined.

The results of numerical modeling of hydrodynamic processes that occur during the period of existence of an autumnal thermal bar in Kamloops Lake, Canada are presented. These results were obtained using a nonhydrostatic 2.5D model in the Boussinesq approximation with allowance for the diurnal variability of radiative and turbulent heat fluxes at the surface of the lake. A series of numerical experiments with various values of water mineralization in the Thompson River have been performed. The calculations show that the mineralization of inflow river waters has a significant effect on the dynamics of horizontal movements of the thermal front and on the pattern of circulation flows induced by the thermal bar during the period of lake cooling.

We substantiate the recommendations for improving the efficiency of hydro- and hydroabrasive cutting of the honeycomb structures that are widely used in aircraft and rockets, obtained by numerical solving of the spatial dynamic problem with allowance for the physico-mechanical and kinematic parameters of a high-speed jet, the physico-mechanical and structural parameters of the treated honeycomb structure, and the parameters of the technological treatment (feeding and the impact angle of the jet with the face surface of the blanks). A physico-mathematical model and a method of numerical analysis of the process have been developed. The influence of the above parameters on the quality of the surfaces of the treated blanks is illustrated. The results of the calculations are compared with the experimental data.