Reconstruction of a photonic crystal structure from a given phase response
Reconstruction of a photonic crystal structure from a given phase response
P. S. Emeliantsev, S. E. Svyakhovskiy
We present a method for designing one-dimensional photonic structures of phase response with predefined shapes and features. An algorithm for constructing such photonic crystal structures has been developed, and numerical modeling of structures' phase and spectral responses has been performed.
Show AbstractAtomic mechanism of transformation between bcc and hcp phases in zirconium under pressure
Atomic mechanism of transformation between bcc and hcp phases in zirconium under pressure
R. I. Sinyakov, M. P. Belov
Using first-principles crystal energy calculation methods, the atomic mechanism of transformation between the bcc ( ) and hcp ( ) phases of zirconium at low temperatures was studied. An accurate two-parameter geometric method has been developed to describe the transformation of a crystal lattice according to the Burgers mechanism. The presented description method takes into account changes in the atomic volume and shape of the crystal lattice during transformation. Using the proposed description of the transformation, the potential energy surfaces of zirconium were constructed during the bcc-hcp transformation in the pressure range from 0 GPa to 25 GPa with a step of 5 GPa. The gradient descent method was used to determine minimum energy paths along potential energy surfaces. Analysis of the results obtained showed a strong dependence of the shape of the energy surfaces and the path of minimum energy on pressure. When the pressure increases to 25 GPa, the shape of the potential energy surface of zirconium changes critically, and a structure appears on the surface with an energy lower than that of the hcp by 10.5 meV. A comparison of the calculation results made using the developed two-parameter method for describing the transformation with oneparameter analogues from the literature showed the inconsistency of the latter as a tool for studying the atomic mechanisms of phase transitions.
Show AbstractNumerical model of cosmic ray propagation in an anisotropic magnetic field of the galaxy
Numerical model of cosmic ray propagation in an anisotropic magnetic field of the galaxy
V. D. Borisov$^1$, Yu. O. Vladimir$^2$, I. A. Kudryashov$^3$
The task of diffusive propagation of cosmic rays (CR) with a general tensor in a model homogeneous magnetic field of the galaxy has been solved in the work, and its stability has been investigated. An algorithm for generating stencils of second-order accuracy difference schemes for a three-dimensional differential equation with tensor components was implemented. This method was applied to solve the problem of diffusive propagation of CR. The work demonstrates the fundamental possibility of determining the energy spectra of CR in various regions of the galaxy, where the distribution of CR sources and the structure of the magnetic field are free parameters.
Show AbstractDetection and evaluation of Slichter 1S1 mode based on Baksan laser interferometer strain data after the 2011 Tohoku earthquake
Detection and evaluation of Slichter 1S1 mode based on Baksan laser interferometer strain data after the 2011 Tohoku earthquake
M. P. Vinogradov$^1$, V. K. Milyukov$^1$, A. V. Myasnikov$^1$, A. F. Yanin$^2$
The 1S1 mode of the Earth's free oscillations (Slichter mode) arises from the oscillations of the Earth's inner solid core relative to the outer liquid core. The search and evaluation of the Slichter mode after the 2011 Tohoku earthquake using data from the Baksan laser interferometer-strainmeter are presented in this paper. An algorithm based on the Maximum Likelihood Method (MLM) was used to search and for estimate the mode parameters. The most likely estimates of the degenerate mode frequency and its splitting parameters associated with the presence of Slichter mode excitation in the studied data are obtained. An estimate of the density jump between the inner and outer core of the Earth is obtained for the found mode periods. For the first time, the potential capabilities of the Baksan stainmeter and the superconducting gravimeters of the IGETS network have been compared for the problem of Slichter mode observation after the same earthquake. The similarity of the found estimate of the mode from strain observations with the previously obtained estimate from gravimetric observations, as well as with the theoretical value from the PREM model, is noted.
Show AbstractStudy of collagen-induced platelet aggregation using low angle light scattering method
Study of collagen-induced platelet aggregation using low angle light scattering method
G. S. Svidelskaya$^{1,2,3}$, E. N. Bruskova$^4$, A. A. Ignatova$^3$, A. A. Filkova$^3$, P. A. Zharkov$^3$, I. V. Mindukshev, S. P. Gambaryan, M. A. Panteleev$^{1,2,3}$
Assessing platelet function is a key to diagnosing bleeding disorders and monitoring the effectiveness of antiplatelet drugs. Recently a method for assessing platelet aggregation based on the phenomenon of low angle light scattering was developed. Measurements are carried out in an medium with a known pH value and calcium concentration. The aim of this work was to study the influence of preanalytical and analytical variables, as well as to compare the results with the method of light transmission aggregometry, already widely used in clinical practice. It was revealed that transporting the sample by car for two hours does not affect the parameters of collagen-induced aggregation. The low angle light scattering method for measuring collagen-induced platelet aggregation has been shown to have good precision under repeatable conditions and was short-term reproducible. The aggregation parameters obtained by low angle light scattering directly correlate with the aggregation parameters measured by transmission aggregometry. Accelerating role of released adenosine diphosphate on collagen-induced platelet aggregation was shown.
Show AbstractNumerical models of nonlinear acoustic waves propagation in problems of medical ultrasound and in some applications of aero- and underwater acoustics
Numerical models of nonlinear acoustic waves propagation in problems of medical ultrasound and in some applications of aero- and underwater acoustics
P. V. Yuldashev$^1$, O. A. Sapozhnikov$^3$, M. M. Karzova$^1$, S. A. Tsysar$^2$, A. V. Kvashennikova$^3$, E. O. Konnova$^1$, V. A. Khokhlova$^3$
The paper considers numerical algorithms used to solve one-way wave propagation equations of nonlinear acoustics, such as the Burgers equation, the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation, and the Westervelt equation. The main results obtained using the developed numerical models in problems of medical ultrasound, in nonlinear aeroacoustics, and in the analysis of nonlinear interactions of intense pump waves in a parametric antenna created in the field of an underwater transducer are presented. The generalization of one-way models to the case of the presence of inhomogeneities of the propagation medium using wide-angle parabolic approximation methods in three-dimensional problems is discussed.
Show AbstractAnalysis of cell death and proliferative activity of cell cultures under proton irradiation in flash mode
Analysis of cell death and proliferative activity of cell cultures under proton irradiation in flash mode
V. V. Martynova, S. V. Akulinichev, I. A. Yakovlev
The study of biological effects of accelerated protons with ultra-high dose rate in and outside the Bragg peak on tumor and normal cell lines is necessary for understanding the consequences of this effect and choosing optimal doses and modes for further use in tumor radiotherapy. In this work, human colon adenocarcinoma cells (HT-29) and normal mesenchymal stem cells (ADSC) of human adipose tissue - fibroblasts were irradiated. Irradiation was carried out using a high-current linear proton accelerator of the INR RAS, which allows varying the energy in the range of 70-230 MeV. The dose was delivered in three different modes: conventional mode (dose rate Ḋ < 3 Gy/s), flash mode (Ḋ ~ 100 Gy/s) and single-pulse flash mode (Ḋ > 104 Gy/s) in the modified Bragg peak region. To analyze cell death, staining with propidium iodide and annexin was performed. For proliferative potential, the EdU test was reproduced. After 24 h, an increase in the number of apoptotic HT-29 cells was detected in all modes, for fibroblasts, an increase in the number of necrotic cells was observed with the conventional irradiation mode and a higher dose compared to other modes. After 48 h, with all irradiation modes, a tendency towards a decrease in the number of necrotic HT-29 cells depending on the dose was observed with the flash/splash modes and a low level of such for fibroblasts. The number of DNA-synthesizing cells by 120 h significantly decreased with all doses and irradiation modes. The curves for the flash and splash irradiation modes were almost parallel. Further studies are needed using wider ranges of cell lines and doses.
Show AbstractReservoir network based on single impurity atoms in silicon
Reservoir network based on single impurity atoms in silicon
A. S. Andreeva, A. S. Trifonov, V. V. Shorokhov, D. E. Presnov, O. V. Snigirev, V. A. Krupenin
This work is aimed at solving the problem of experimental implementation and study of single-electron reservoir networks with As impurity atoms in a quasi-two-dimensional near-surface layer of a solid-state matrix based on silicon-on-insulator (SOI) material. The study of electron transport in the fabricated experimental structures showed the presence of horizontal sections of the Coulomb blockade on the current-voltage characteristics (CVC), typical of single-electron transport. The shape of the recorded CVC between a pair of selected control electrodes of the reservoir network significantly depended on the potentials of the remaining surrounding electrodes, which changed the structure of the conducting channels passing through the impurity centers. Restructuring the control voltages, using the internal nonlinearity of the system of disordered single As impurity atoms, which has a colossal state space, made it possible to demonstrate the possibility of implementing a tunable nanoscale current switch and the logical functions "NOT", "AND", "OR" in a single-electron reservoir network. To find the configuration of the reservoir network necessary for the implementation of functional elements, a vector tuning method was used.
Show AbstractElectromagnetic form factors of the deuteron in the dibaryon model of NN interaction
Electromagnetic form factors of the deuteron in the dibaryon model of NN interaction
M. N. Platonova, I. T. Obukhovsky
The electromagnetic form factors of the deuteron have been calculated within the dibaryon model for nuclear forces, which is based on the resonance mechanism of formation of a six-quark bag (dibaryon) in a NN collision. The calculations take into account both the single-nucleon currents (impulse approximation) and additional contributions induced by the formation of an intermediate dibaryon. For the calculations of form factors, two versions of the dibaryon model, of 2002 and 2022, have been used. It is shown that both versions of the model reproduce experimental data well for all three deuteron form factors in the region of transferred momenta Q < 0.8 GeV/c. At higher values of Q, the predictions of different versions of the model deviate from each other, with one of them (2002) better describing the magnetic form factor, and the other (2022) - the charge one. Possible reasons for the discrepancy found between the theoretical calculations and experimental data for large momentum transfers are discussed.
Show AbstractSimple finite-dimensional model of the metastable state
Simple finite-dimensional model of the metastable state
A. I. Dubikovsky, P. K. Silaev
We have constructed an approximate analytical solution of the spectral problem for a finite-dimensional matrix of a special kind, which turns out to be a very simple and quite satisfactory model of the metastable state. Most of the characteristic properties of the metastable state are reproduced: line shape, decay dynamics, and density of states. The correctness of the approximate analytical solution was verified by direct numerical calculations. The proposed model is a finite-dimensional analog of the Fano formalism.
Show Abstract