Combining chiral optical Tamm states into one mode of a hybrid structure
Combining chiral optical Tamm states into one mode of a hybrid structure
N. V. Rudakova$^{1,2}$, S. Y. Vetrov$^{1,2}$, I. V. Timofeev$^{1,2}$
The excitation conditions and effective control possibilities are investigated for two coupled chiral optical Tamm states arising at boundaries of a crystalline liquid crystal coupled with polarization-preserving anisotropic mirrors. Numerical modeling has shown that varying the parameters makes it possible to control the magnitude of transmission coefficient of the structure, the optimization of the spectral characteristics, as well as the profile of the local field intensity. In this case, the polarization of the incident light has a significant effect on the excitation efficiency. It is shown that the hybrid mode of two chiral optical Tamm states smoothly transforms into a single Fabry-Perot mode in the process of increasing coupling between them.
Show AbstractFacility for measurement of sky background variations in the infrared at the Caucasian Mountain Observatory of the SAI MSU
Facility for measurement of sky background variations in the infrared at the Caucasian Mountain Observatory of the SAI MSU
I. A. Komarova$^1$, A. M. Tatarnikov$^2$, S. G. Zheltoukhov$^3$
The description of the device constructed at the SAI MSU based on a commercial infrared light-sensitive module for the study of the sky background brightness (SBB) distribution in the infrared is presented. The procedure of observations with the instrument and the algorithm for accounting for the contribution of the instrumental background to the total signal are described. The results of measurements of the SBB at the Caucasus Mountain Observatory at wavelengths of 3.7~$\mu$m and 4.7~$\mu$m carried out in December 2024 are presented. An estimate of the SBB at zenith corresponding to the star $7.3^{\rm m}$ at 1 arcsec$^2$ of the sky is obtained.
Show AbstractMorphological methods for estimating the relative time shift of infrasound signals
Morphological methods for estimating the relative time shift of infrasound signals
A. F. Idrisov, A. I. Chulichkov
The present work is devoted to solving the problem of estimating the relative time delay of infrasound signals propagating from a pulse source along different trajectories in a layered homogeneous atmosphere. To solve the problem, morphological methods of signal analysis are used, developed at the Department of Mathematical Modeling and Computer Science, Faculty of Physics, Lomonosov Moscow State University. The methods are applied to the infrasound signals data recorded by barographs located at different points on the Earth’s surface. The time delay of the signals from different barographs allows us to estimate the direction of arrival of the sound wave, which allows us to further determine the position of the signal source and study the structure of the atmosphere.
Show AbstractAnalysis of hystersis behavior of the lock-in range in a Zeeman ring laser
Analysis of hystersis behavior of the lock-in range in a Zeeman ring laser
M. E. Grushin$^2$, E. G. Lariontsev$^1$, I. I. Savel'ev$^2$, E. V. Soukhov$^2$
Broad hystersis area of the lock-in range in a Zeeman ring laser till now were not described theoretically. In this paper we propose a new model accounting an additional coupling of the counterpropagating waves due to their diffraction on the gratings induced in the cavity mirrors. Hysteresis area of the lock-in range have been studied experimentally.
Show AbstractSoftware implementation of orbit construction methods in the CR3BP
Software implementation of orbit construction methods in the CR3BP
T. A. Syachina, A. G. Rudnitskiy
This paper presents a software implementation of methods for accurate calculation of orbital parameters for near-Earth space, as well as for the vicinity of the Lagrange points. The program is based on modern mathematical models and algorithms providing high accuracy and efficiency of calculations. Various perturbing factors are taken into account and the possibility to model spacecraft motion in complex gravitational conditions is implemented. The results of the program are compared with known software solutions for ballistic and navigation calculations.
Show AbstractRegistration of pulsed terahertz radiation by a superconducting bolometer in the process of parametric dowm-conversion
Registration of pulsed terahertz radiation by a superconducting bolometer in the process of parametric dowm-conversion
K. A. Kuznetsov$^2$, N. I. Tatyana$^2$, I. V. Pentin$^3$, G. K. Kitaeva$^{1,2,4}$
The statistical distributions of the output signals of a superconducting bolometer exposed to weak photon pulses with a frequency of 1 THz from a pump with a pulse duration of 30 ps are investigated. Terahertz pulses are obtained by the method of strongly nondegenerate parametric scattering in a LiNbO3 crystal cooled to 4.8 K. Various scenarios of the response of superconducting bolometer to excitation by a small number of terahertz photons are discussed.
Show AbstractOn modeling acoustic fields in a marine waveguide with refined boundary conditions on the surface and bottom
On modeling acoustic fields in a marine waveguide with refined boundary conditions on the surface and bottom
Yu. I. Papkova$^1$, S. O. Papkov$^2$
The problem of the sound field of a point sound source situated in a non-ideal marine waveguide is considered. The boundaries of the waveguide are assumed to be plane-parallel, there are three layers: a water layer with a non-uniform refractive component of the speed of sound, a layer of liquid sediments, and a bottom elastic layer on a rigid base. The water layer is limited by a homogeneous air half-space. Analytical expressions for impedance functions at the boundaries of the water layer were obtained for the first time for this waveguide model, which makes it possible to construct the Green's function of the vertical boundary value problem. Moreover, exact values for the residues of the Green's function are found, which allow one to write an exact analytical representation for the sound pressure potential as a sum of normal modes. It is shown that the influence of the continuous spectrum (integrals along the branch cuts) is small even at small distances from the source. As the thickness of the elastic layer decreases, the discrete spectrum of the problem tends to the values for a classical waveguide, and at a sufficiently large thickness and attenuation it is similar to the discrete spectrum of the Pekeris elastic waveguide. Examples of numerical implementation for waveguide parameters typical for the Black Sea waters are given.
Show AbstractSPRING ATMOSPHERIC BLOCKINGS IN THE NORTHERN HEMISPHERE: CHANGES IN RECENT DECADES (1993-2023)
SPRING ATMOSPHERIC BLOCKINGS IN THE NORTHERN HEMISPHERE: CHANGES IN RECENT DECADES (1993-2023)
I. I. Mokhov$^{1,2}$, J. R. Eremin$^1$
This paper presents an analysis of the spring atmospheric blockages (SAB) in the Northern Hemisphere (NH) in 1992-2023. The results of the analysis indicate a significant increase in blocking activity in the atmosphere of the joint venture in recent decades. The noted trend is manifested against the background of a general increase in the near-surface temperature of the NH in the spring seasons. The following SAB parameters were used in the study: quantity, average duration, total duration, intensity, and size. There were obtained estimates of the statistically significant increase in the total duration of the SAB, their number and size with an increase in the average spring near-surface temperature in the NH.
Show AbstractSome physical factors in the development of secondary cancers in patients who have undergone radiation therapy.
Some physical factors in the development of secondary cancers in patients who have undergone radiation therapy.
A. A. Shcherbakov$^{1,2}$, I. V. Khramov$^1$, E. N. Lykova$^{1,2}$, S. A. Gavrilova$^3$, F. R. Studenikin$^{1,2}$, A. P. Chernyaev$^{1,2}$
The review presents methods of assessment and statistical data on the occurrence of secondary malignant neoplasms in patients who have undergone radiation therapy. The influence of factors such as the age and sex of the patient, the location of the primary tumor, and the method of radiation treatment is examined. It has been established that the highest risks of developing secondary cancer are observed in children, women, and with the use of photon radiation therapy. A comparison with experimental data obtained from animals, which revealed similar patterns, is provided. Special attention is given to risk assessment models depending on the radiation dose. The main models used for risk assessment are highlighted. Certain factors that may influence the development of secondary cancer during radiation therapy are identified, including the impact of secondary particles and the use of medical imaging.
Show AbstractFluorescence of various antropogenic pollutants of hydrosphere when probing of water column by pulsed ultraviolet lidar
Fluorescence of various antropogenic pollutants of hydrosphere when probing of water column by pulsed ultraviolet lidar
L. E. Yakushkin
A criterion has been developed for detecting anthropogenic debris floating on the water surface when probing the water column with a pulsed ultraviolet laser with a wavelength of 355 nm probing radiation. The criterion was applied to lidar sounding data of the near-surface layer of the sea in several expeditions to the Black Sea. The conditions of applicability of the proposed criterion for the detection of marine debris are formulated. The results obtained using this criterion are compared with visual observation data. The possibility of using the criterion to assess the extent of pollution of the World Ocean is shown.
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