Nematic liquid crystal elements spatially structured in the azimuthal direction represent a special type diffraction grating capable of achieving a diffraction efficiency of up to 100%. This paper is devoted to the development and study of the spatial polarization properties of a liquid crystal diffraction polarizing twist element, in which a phase profile equivalent to a diffraction polarizing grating is realized by spatially modulating the topology of the director orientation using the method of polarization holographic recording of surface anisotropy in the azo dye AtA-2 layer. The efficient electrical control possibility of the diffraction and the structured element polarization properties, their ambivalence when changing the side of light input into the liquid crystal element are experimentally demonstrated. The optimal value of the external control voltage corresponding to the maximum diffraction efficiency above 90% for circularly polarized radiation is determined.
This paper presents a continuation of a study of taking into account the quantum-gravity corrections (qgcs) for primordial black holes (pbhs) and of the corresponding inferences in cosmology. The first part is devoted to application of the above-mentioned qgcs in the de Sitter epoch to solution of the Dark Energy Problem. In the process the Dark Energy is understood as the vacuum energy the density of which is identical to the cosmological constant within constant factors. The explicit formula for the transformation of this density due to qgcs for pbhs with the Schwarzschild-de Sitter metric in the de Sitter space has been derived. The case of a dynamic cosmological term in this formalism has been considered. The second part of the work is devoted to studies of qgcs for pbhs during the radiation-dominant era. At first it has been demonstrated that the inclusion of these corrections shifts all the parameters in accordance with the formulae applicable to the de Sitter epoch. Then the accretion and evaporation processes in this pattern are studied for pbhs. It has been shown that, compared with a semiclassical consideration, in this case the accretion rate is lowering, whereas the evaporation rate is growing, i.e., in this pattern the evaporation processes are intensified.
In this article, we propose a modified model for the spread of SIR disease. The model is based on an assumption of the existence of two relatively separate groups, which are called bubbles. In the model we use, it is assumed that the rates of disease spread vary in both groups under consideration and between the groups too. A numerical experiment has been conducted for the proposed model.
In this work, we explore the possibility of chimera states in the locally coupled q-deformed Lozi maps. The deformation is introduced using the Jaganathan-Sinha q-deformation scheme, which modifies the local map while smoothly recovering the standard Lozi map in the limit q -> 1. We observe that the q-deformed map exhibits significant modifications in its dynamical behavior compared to the standard case. Through analytical considerations and numerical simulations, we analyze fixed points, stability, bifurcation structure, and routes to chaos as functions of the deformation parameter. Chimera states are represented by stable coexisting synchronous and asynchronous domains in a lattice of coupled identical oscillators promoted by non-local or global coupling. An analogous 'spatial intermittency' is also observed in coupled map lattices. This work demonstrates that chimera states are not restricted to oscillatory systems or standard maps, but can also emerge in discrete-time systems with rationally deformed dynamics under purely local interactions. This indicates that chimera states are a robust and generic feature of a wide class of non-linear systems.
This article looks at modern cybersecurity methods in educational institutions, using a university with a developed IT infrastructure as an example. The relevance of this work is determined by the growing number of cyberattacks on educational institutions' networks and the need to implement smart information protection systems. A number of typical threats are considered, including unauthorized access, malware, and phishing, as well as the characteristics of the university infrastructure that affect the risk of cybersecurity incidents. The object of this study is deep learning methods applied to the analysis of information security events and the detection of malicious activity. Approaches to normalizing operating system and application event logs are proposed to ensure data unification, as well as a method for vectorizing events by highlighting key features to prepare high-quality input data for deep learning algorithms. The proposed architecture of the information protection system based on explainable deep learning includes modules for collecting and normalizing events, vectorizing them, analyzing them using neural networks, and visualizing the results.
In this paper, within the framework of the Memory Functions Formalism, we study cooperativity in neural processes, which manifests itself in the effects of frequency-phase synchronization of magneto encephalogram signals measured at different leads when a person is exposed to flickering light stimuli. During the analysis of the synchronization effects in simultaneously recorded signals, statistical characteristics of the interaction of areas of the cerebral cortex with the most pronounced manifestations of coherence when exposed to flickering stimuli were determined, considering the rhythms of the brain. Stratification of phase portraits of orthogonal dynamic variables, an increase in Markov effects, as well as the intensity of alpha-, beta-activity in the frontal and occipital areas of the cerebral cortex of healthy subjects were discovered when light stimuli were applied. The results obtained will be of interest to specialists whose area of interest is neuroscience, data science or cognitive psychology.
The action of light pressure forces of an evanescent electromagnetic wave, formed by total internal reflection at the dielectric-liquid interface, on dielectric spherical nanoparticles located in a liquid medium is considered. An analytical solution for the equation of motion of a nanoparticle under the action of the scattering force of an evanescent wave, taking into account the drag force of the medium in the approximation of small displacements, is obtained. It is shown that the applicability region of linearization does not strongly depend on the sign of the discriminant of the characteristic equation of the linearized system, but rather on the initial conditions and observation time.
Acoustic emission of fiberglass composite material during tensile loading is characterized experimentally by a set of records. Regularity of recorded data enables prediction of the sample rupture when approaching the critical loadings. For this purpose a new statistical method is formulated. The prediction is performed by comparing acoustic activity of tested and representative samples. Results of the prediction agree with the experimental data and confirm the hypothesis that acoustic emission detection provides a proper basis for a simple nondestructive testing of very complex fiberglass composite.
We derive the Dirac equation in the background of the Newman-Unti-Tamburino (NUT) spacetime by applying the tetrad formalism, and separate the angular and radial parts. We get the system of two differential equations for angular functions and solve them in terms of hypergeometric functions. Then a NUT-charge dependent quantization rule for the angular separation constant has been established. As a result of studying the radial equations, we demonstrate that the probability of particle-antiparticle production on the outer event horizon decreases with the increase of the NUT charge. For the massless fermion, we construct the solution of the radial system of Dirac equation in terms of the confluent Heun functions that allows to get the NUT-charge dependent scattering resonances. Under the assumption of small NUT charge, we study the extremal NUT black hole with a single horizon, when the Bekenstein-Hawking entropy vanishes identically, and reveal the non-zero NUT charge effects in wave characteristics.
The gluon dominance model is developed to describe multiparticle production of secondary particles at high energies in lepton and hadron interactions, including annihilation processes and heavy quarkonium decays. According to this model, the multiparticle process is divided into two stages. The first stage describes the development of a quark-gluon cascade as a Markov branching process in the region of perturbation QCD. For the second stage, the transformation of quarks and gluons into observable hadrons (hadronization), a phenomenological scheme is proposed. It is universal and based on an experiment. The gluon dominance model demonstrates good agreement with data over a wide energy region. It testifies that in hadron interactions valence quarks remain in the leading particles, and gluons are the sources of secondary hadrons. Quantitative estimates of the model parameters confirm the fragmentation mechanism of hadronization in leptonic interactions and the recombination mechanism in hadronic ones. The model description of the experimental distributions on the number of neutral pions in proton interactions at 50 GeV beams in the high multiplicity region are presented for the first time. It is shown that the main contribution to this region is made by gluon fission. These results can be useful for the development of Monte Carlo generators.
Afterpulse statistics were experimentally studied for a number of single-photon detectors based on silicon avalanche photodio des under intense illumination with nanosecond pulses. A significant increase in the probability of afterpulse occurrence was demonstrated for a large number of photons absorbed by the detectors. These results may be important for optimizing detector performance in quantum cryptography and for artificial pulsed neurons based on vertical-cavity lasers and single-photon avalanche photodio des, one of whose operating modes is based on the action of sufficiently intense laser pulses.
Neutron irradiation damage is one of the most critical degradation mechanisms in reactor pressure vessel (RPV) steel. Traditional displacement damage models, such as NRT-DPA, tend to overestimate stable defect production by neglecting athermal recombination effects. However, the generated vacancies undergo athermal relaxation, leading to a reduction in the stable number of vacancies. This study focuses on incorporating athermal relaxation effects into the final vacancy distribution, building on the results of the previous work (Khrushchinsky et al., 2024) where the distribution was obtained without considering athermal relaxation. The calculations are performed for the VVER-1200 reactor pressure vessel using the arc-DPA (displacements per atom with athermal relaxation correction model), providing a more accurate assessment of radiation-induced damage. Additionally, we estimate the annual arc-vacancy accumulation, providing improved lifetime assessments for the VVER-1200 RPV. This work highlights the importance of advanced damage models for accurate safety evaluations in nuclear reactors.
A comparative analysis of the results on the motion of a non-relativistic particle in a Cornell potential in a quantum mechanical problem for real and imaginary Lobachevsky spaces is conducted. Based on numerical calculations, it is established that, unlike in the case of real space, for identical parameter values, a discrete spectrum is absent in imaginary space. An example of a set of parameters for which a discrete spectrum exists is given.
In this study we focus on the non-equilibrium phase transition whose asymptotic critical behavior is governed by the dynamic isotropic percolation universality class. In order to quantitatively characterize universal properties associated with this class, we employ a field-theoretic formulation of the model augmented with perturbative renormalization group technique. Utilizing such approach enables us to systematically compute the critical exponents in higher orders of perturbation theory. In particular, we perform an analysis to the three-loop precision. To this order we determine the renormalization constants and present relations for critical exponents in terms of critical dimensions. Finally, we also present numerically estimated values of critical exponents obtained from perturbation theory.
Development of detection systems such as scintillation crystal/carbon-nanotube bilayer systems is needed for nuclear applications. It allows to clarify the nature of nuclear decays with creation of electron-positron pairs and to search for double electron-capture decays and neutrinoless double beta-decay processes for discovering Majorana particles. We design a novel system composed of scintillation crystal NaI(Tl) and carbon-nanotube two-dimensional crystalline layers to record gamma-radiation spectra. We perform investigations by means of the developed detector system for exploring interactions between rolled-up graphene walls of carbon nanotubes (CNTs) and 60 & Scy;o-and 137 & Scy;e gamma rays. It was shown that CNTassembly-enhanced scattering of gamma-rays from Co-60 and Cs-137 decays occurs in an intermediate-size detector NaI(Tl) crystal. A hight-performance method based on the enhancement phenomena is offered to detect electron-positron annihilation from cascade events such as nucleus processes of internal energy conversion. We predict and experimentally confirm that the internal conversion in 60Ni nuclei proceeds with generation of positronium ions (P-S ) and there can appear excited P-S states. The excess energy deposition of 3.8-3.9 keV into the detector NaI(Tl)/carbon-nanotube system is evidence of the bound electron-positron pairs from internal energy conversion in nuclei of both 60Ni and 137mBa.
The detection of skin diseases is crucial due to their visibility and potential for transmission. However, clinical diagnosis presents challenges, often proving time-consuming and ineffective. Consequently, there is a pressing need for content-based image retrieval (CBIR) techniques to automate the detection of skin diseases. Effective multi-faceted ranking algorithms are widely used in CBIR, representing images through low-level features (color, texture, shape) and high-level features extracted from Convolutional Neural Networks (CNNs). Low-level features enable rapid detection of visual differences and are invariant to rotation and translation. Conversely, CNN-derived high-level features provide a richer semantic description. However, single query image systems may not fully capture image complexity, leading to inaccurate retrieval. This study introduces a novel method to improve the accuracy of skin disease image retrieval by combining ranking results from multiple query images. By integrating information from two input images, the proposed method enhances retrieval accuracy and efficiency. This approach leverages diverse semantic information for a more comprehensive and accurate retrieval process. Experiments on the Dermnet dataset demonstrate the effectiveness of this method in improving image retrieval quality.
This paper based on the previously obtained results begins a study into the problem how parameters of the Relic Gravitational Waves (RGW) are shifted due to quantum-gravitational corrections to primordial black holes in the early Universe. Explicit formulae have been derived for the corresponding shifts of the wave equation, adiabatic vacuum approximation boundaries, the energy of each created RGW, power spectra of all cosmological expansion stages. It is shown that some of the parameters acquire higher values, specifically the adiabatic bound for the frequencies and the energy of each created RGW. Other parameters retain their values but their domains of definition are shifted, for example, the present power spectrum of RGWs. In the concluding part, the problems for further relevant studies are formulated.
The cross section of the process e+e--> pi+pi-pi 0 has been measured with the Cryogenic Magnetic Detector (CMD-3) at the electron-positron collider VEPP-2000. The measurement is based on data samples that were collected in the center-of-mass energy range root s = 760-798 MeV corresponding to an integrated luminosity of Lint = 18.4 pb-1, covering the kinematic region of the omega (782) isoscalar resonance. The total systematic uncertainty of the cross section measurement is about 2%, dominated by the luminosity determination uncertainty of 1.5%. The results are compared with the previous most precise measurements from experiments. The measured cross section is used to evaluate the leading-order hadronic vacuum polarization contribution of the 3 pi channel to the muon anomalous magnetic moment (a3 pi mu ).
Random processes with jumps find application in various fields of research, such as economics. Generally researchers are interested in the values of mathematical expectations from processes of this kind. Previously, the author has proposed a formula for the approximate calculation of mathematical expectations from processes defined by a stochastic differential equation containing a process with jumps. In this paper an accuracy estimate is obtained for the earlier proposed formula.
The full CMS and ATLAS Run 2 datasets with time-integrated luminosity of 137 and 139 fb-1 in the diboson channels are used to probe benchmark models with extended gauge sectors such as left-right symmetric (LR) and the sequential standard model (extended gauge model, EGM), that predict the existence of neutral Z'- and charged W'- bosons decaying to a pair of bosons ZH and WH in the semileptonic final state. These benchmark models are used to interpret the results. Exclusion limits at the 95% C.L. on the Z' and W' resonance production cross section times branching ratio to electroweak gauge boson pairs in the resonance mass range between 1.0 and 5 TeV are here converted to constraints on Z-Z' and W-W' mixing parameters and masses. We present exclusion regions on the parameter spaces of the Z' and W' and show that the obtained exclusion regions are significantly extended compared to those derived from the previous analysis performed with Tevatron data as well as with the CMS and ATLAS data collected at 7 and 8 TeV in Run 1. The reported limits are the most restrictive to date.
