Correlations of neutron star characteristics with properties of nucleon and hyperon interactions
Correlations of neutron star characteristics with properties of nucleon and hyperon interactions
A. I. Nasakin$^{1,2}$, D. E. Lanskoy$^1$, S. A. Mikheev$^{1,2}$, A. M. Potokin$^1$, T. Yu. Tretyakova$^{1,2}$
The hyperons appearance at densities several times greater than the nuclear one in the massive neutron stars interior has a significant impact on neutron star characteristics. Using various parameterizations of Skyrme forces, we calculated the equations of state of neutron star matter and analyzed possible correlations between the observed characteristics of neutron stars and the properties of nucleon and hyperon interactions. The $\Lambda N$ interaction contracting power, which characterizes the ability of the $\Lambda$-hyperon to modify the nucleon core of the hypernucleus, has the strongest influence on the density of matter at the point of hyperon appearance and, consequently, on the characteristics of neutron stars. The relationship between astrophysical quantities and the properties of nucleon interactions weakens with the appearance of hyperons, but in most cases remains. The incompressibility of nuclear matter, quantities reflecting the behavior of the symmetry energy at high densities, and the hyperon interaction contracting power determine the maximum mass of a neutron star.
Show AbstractOptical Simulator For Quantum Key Distribution
Optical Simulator For Quantum Key Distribution
L. V. Biguaa, S. P. Kulik
In this paper, we propose and test a scheme of a novel optical system for the numerical and experimental study of quantum key distribution (QKD) systems, as well as various attacks on the implementation of known protocols in a plug-and-play mode. Moreover, the system exploits the standard laboratory tools such as general purpose diode lasers and photodiode detectors. This allows to perform QKD demonstration without need for deploying an expensive and technically complex actual QKD system. Such a paradigm seems to be useful in the context of intensive developing of QKD systems for research purposes Firstly, it is linked to the emerging need in numerical simulation of QKD systems for research purposes. In turn, the experimental realization of such an approach is essential for practical demonstration of QKD systems as well as training the specialists in the field of quantum ciphering. Moreover, the currently available systems only allow researchers to experimentally reproduce the simplest eavesdropper (Eve) attacks on QKD protocols, such as the intercept-and-resend attacks. They can also only numerically simulate a wide range of attacks, but using enough sophisticated systems. In contrast, the suggested system allows for both numerical and experimental replication of attacks ranging from simple ones to technically challenging PNS-like ones in a simple plug-and-play manner.
Show AbstractOptimization of the orbital parameters of spacecraft in the task of measuring the Earth's gravitational field
Optimization of the orbital parameters of spacecraft in the task of measuring the Earth's gravitational field
A. I. Filetkin
An analytical method has been developed for optimizing the orbital parameters of a space constellation for measuring the Earth’s gravitational field (EGF). The method is based on identifying the repeatability cycles of sub-satellite tracks under unperturbed Keplerian motion, subject to the condition that an integer number of satellite revolutions occurs over an integer number of nodal days. By comparing analytical and numerical approaches, a functional relationship was derived that allows determining the spacecraft orbital altitude for perturbed motion with an accuracy of up to 30 meters. The paper considers two time scales for orbit integration: a full coverage cycle (30 days) and a subcycle (7 days). For the obtained optimal configurations, full-scale integration of the orbital motion and subsequent recovery of the Earth’s gravitational field (EGF) were performed, enabling an assessment of the influence of orbital parameters on the accuracy of the recovered field.
Show AbstractDevelopment of Medical Physics in Russia
Development of Medical Physics in Russia
A. P. Chernyaev$^{1,2}$, K. A. Andrei$^{1,2}$, E. N. Lykova$^{1,2}$, F. R. Studenikin$^{1,2}$, A. A. Shcherbakov$^{1,2}$
This review focuses on the history of medical physics in Russia and at Moscow University, highlightingkeydevelopmentalmilestones.AspecialemphasisisplacedonMoscowUniversity’s historical role in advancing physical methods and technologies in medicine. The paper notes significant ideas from Russian scientists that formed the basis for high-tech medical devices and systems, as well as crucial moments in the development of nuclear-physical technologies for these purposes. The review describes the stages of creation and improvement of high-tech radiation physics installations, methods, and technologies in domestic medicine. It traces the development trends of radiation technologies in medicine in Russia and globally, along with the needs of Russian healthcare for its sustainable development under current conditions. The paper also outlines the state of staffing in this area of medicine and presents the principles for building a system of personnel training and retraining at Moscow University to facilitate the development and implementation of radiation technologies in medical practice. Finally, it analyzes trends in the application of nuclear-physical methods in Russian medicine and proposes effective approaches to ensure the technological independence of our country’s economy.
Show AbstractStudy of the influence of quantum effects on energy absorption by coated plasmonic nanoparticles using the discrete source method
Study of the influence of quantum effects on energy absorption by coated plasmonic nanoparticles using the discrete source method
Yu. A. Eremin, V. V. Lopushenko
The influence of quantum effects on the absorption cross section of gold nanoparticles with a polymer coating is considered. Such layered structures are used as photothermal agents in the treatment of oncological formations. A modification of the discrete source method is used for the study. Modeling of quantum effects in the plasmonic core is carried out based on mesoscopic boundary conditions with Feibelman parameters, which allow taking into account such quantum effects as spatial nonlocality, displacement of the electron cloud with respect to the metal surface, and Landau attenuation. As a result of the studies, it was found that by changing the geometry of the plasmonic core, it is possible to control the position of the absorption cross section maximum in the transparency window of biomaterials, while variation of its volume affects only the cross section amplitude. It is shown that taking into account the quantum effect leads to a shift in the absorption cross section maximum to the short-wave region by 10-15 nm, as well as a slight decrease in its amplitude within 5%.
Show AbstractComputer model of primary platelet adhesion to von Willebrand factor in a terminal arteriole
Computer model of primary platelet adhesion to von Willebrand factor in a terminal arteriole
A. V. Belyaev
Secretion of von Willebrand factor by inflamed endothelium is considered one of the biophysical pathways initiating microvascular thrombosis in infectious diseases. At the initial stage of this process, the attachment of the first layer of platelets to von Willebrand factor is fundamental, while mechanical and hydrodynamic phenomena significantly influence the dynamics of thrombosis. In this study, computer modeling methods were used to investigate the biomechanics of platelet adhesion to inflamed endothelium in a microvessel. Calculations were performed over a range of hemodynamic parameters characteristic of small arterioles. The results demonstrate that platelet adhesion becomes more intense with increasing blood flow velocity due to the synchronous manifestation of two physical mechanism
Show AbstractGeodynamics of the Vladikavkaz region based on GNSS observations at the Ossetian geodynamic testing ground
Geodynamics of the Vladikavkaz region based on GNSS observations at the Ossetian geodynamic testing ground
A. P. Mironov$^1$, V. K. Milyukov$^1$, A. N. Ovsyuchenko$^2$, K. M. Khubaev$^3$, S. O. Dzeboev$^3$
An analysis of the contemporary geodynamic situation in the Vladikavkaz area is presented, based on long-term GNSS (Global Navigation Satellite System) observations at continuous stations and field sites at the Ossetian geodynamic testing ground. Velocity estimates are made in two reference frames: the global International Terrestrial Reference Frame (ITRF) and the local, relatively fixed Eurasia. In ITRF, the movement of the region is consistent with the overall movement of the Greater Caucasus region in a northeasterly direction at a rate of 27–30 mm/year. The results of velocity profiling in the local reference frame showed a number of opposite-directional kinematic features that define the contemporary geodynamic regime of this area. These results, as well as those from seismological studies, testify that the city of Vladikavkaz is located in a region with relatively active geodynamic processes.
Show AbstractNew data on photodisintegration of atomic nuclei from the results of experiments on the beams of Bremsstrahlung
New data on photodisintegration of atomic nuclei from the results of experiments on the beams of Bremsstrahlung
V. V. Varlamov$^1$, A. I. Davydov$^2$, V. N. Orlin$^3$
It was shown that in many cases that is possible to obtain new unknown before data on photodisintegration of atomic nuclei, primarily on photoneutron reaction cross sections basing on published data of experiments carried out using Bremsstrahlung. Such type possibilities were realized for 52Cr and 68Zn. At the first time such unpublished data on the reactions σ(γ, 2n) и σ(γ, xn) = σ(γ, 1n) + 2σ(γ, 2n) in the case of 52Cr and σ(γ, 1n), σ(γ, 2n) and σ(γ, sn) = σ(γ, 1n) + σ(γ, 2n) in the case of 68Zn were determined using experimental published data. It was found that experimental partial reaction cross sections on 52Cr do not meet objective physical criteria of data reliability. New cross sections of the reactions 52Cr(γ, 1n), 52Cr(γ, 2n)50Cr meeting those criteria were evaluated using the experimental-theoretical method and used for determination of total photoneutron reaction 52Cr(γ, sn) cross-section. Using this method, new unknown before cross sections of partial reactions 68Zn(γ, 1n)67Zn and 68Zn(γ, 2n)66Zn and total photoneutron reaction cross-section 68Zn(γ, sn) were determined at the first time using the unique only one published neutron yield cross-section 68Zn (γ, xn).
Show AbstractStudy of Static Fields of Axion-like Particles in the Vicinity of a Rotating Neutron Star
Study of Static Fields of Axion-like Particles in the Vicinity of a Rotating Neutron Star
A. V. Bedda$^{1,2}$, M. O. Astashenkov$^{1,2}$, P. A. Vshivtseva$^{1,2}$, V. I. Denisov$^{1,2}$
The static part of the axion-like field created by a rotating neutron star, such as a pulsar or magnetar, has been calculated. It has been shown that this static field is distributed anisotropically around the star, forming a dilaton halo. Therefore, this halo will act as an anisotropic lens for electromagnetic waves.
Show AbstractRelative intensity of the low-frequency Raman signal of nucleic acids, proteins, and lipids
Relative intensity of the low-frequency Raman signal of nucleic acids, proteins, and lipids
O. D. Parashchuk$^1$, A. Yu. Sosorev$^1$, T. S. Mustafin$^1$, A. A. Trubitsyn$^1$, I. V. Chicherin$^2$, P. E. Ul'yana$^2$, D. Yu. Parashuk$^1$
The compaction of biomolecules largely determines their functionality. It has previously been shown that the compaction of DNA and RNA can be estimated from the relative intensity of the low-frequency (LF) region of the Raman scattering spectra, but the applicability of this approach to complexes and mixtures of DNA with other biomolecules remained uncertain due to the unknown relative contribution of these molecules to the LF Raman spectrum. In this work, the experimental Raman spectra of DNA, protein, and fatty acid are compared, and it is shown that the intensity of the LF region is significantly higher for native DNA than for the other two types of biomolecules. Additionally, it is demonstrated that when a complex is formed between DNA and protein, the shape of the Raman spectrum of the complex is similar to that of the DNA spectrum, and the relative intensity of the LF region of the spectrum decreases. This indicates that the Raman signal from DNA dominates and that DNA becomes more compact during complex formation. The obtained results contribute to the development of a method for assessing the compaction of various biomolecules based on the analysis of LF Raman spectra and its application to complex biomolecular systems, such as cell nuclei.
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