Calculation of the vacuum energy density in quantum field theory gives a value $10^{122}$ times higher than the observed one, and many proposed approaches have not solved this problem and have not calculated its real value. However, the application of the microscopic theory of superconductivity to the description of the physical vacuum on the Planck scale made it possible to solve the problem...
Systemic shocks inevitably lead to negative socioeconomic outcomes. The COVID-19 pandemic and the war in Ukraine are the prominent examples of such systemic shocks. Shock-initiated spreading processes often have a domino effect on both the social and economic levels. The war in Ukraine, despite its devastating effect on the Ukraine’s society and economy, has not led to the full collapse,...
Introduced the quantitative measure of the structural complexity of the graph (complex network, etc.) based on a procedure similar to the renormalization process, considering the difference between actual and averaged graph structures on different scales. The proposed concept of the graph structural complexity corresponds to qualitative comprehension of the complexity. The proposed measure...
Confined ionic liquids exhibiting exciting physics are essential in modern technologies. The narrow conducting confinements cause exponential screening of the electrostatic interactions between ions, allowing the development of models with short-range interactions that can provide analytical insights into the charge storage mechanisms. In this contribution, we present a lattice model for ionic...
Transport processes of a passive scalar in random velocity fields are observed in plasma systems, atmosphere, oceanic currents, etc. The task of the theoretical description is to reproduce the temporal evolution of an ensemble of particles moving in such a field based on the known statistical characteristics of the velocity or force fields. The most known example is Brownian motion, the...
This work shows how a kinetic process is formed in a dynamic system that is in a non-stationary coupling with the environment. It is assumed that the environment has a large number of degrees of freedom and therefore transitions in a dynamic system do not change the state of the environment. However, due to the openness of a dynamic system, the environment is capable of modifying both the...
The scattering of gas flow on an obstacle can lead to the formation of nonequilibrium steady states (NESS), such as stationary obstacle wakes. These systems may undergo nonequilibrium phase transitions, resulting in the emergence of nonlinear steady-state gas structures under critical conditions. One notable example is the formation of a stratum-like, or two-domain, gas structure ahead of the...
The development of Bogolyubov reduced description method
in the application to spin and quasispin systems
Sokolovsky A. I., Lyagushyn S. F.
Oles Honchar Dnipro National University
The reduced description method (RDM) is based on the Bogolyubov’s idea that at large time the non-equilibrium state evolution of a macroscopic system can be described with the limited number of parameters....
Modified potential energy theorem in radiating systems: Implementation in MATLAB
Fields of mathematics such as mathematical physics often use potential energy specifically to describe the dynamics of various physical systems. Classical potential energy theorems are known to play a key role in understanding and analyzing mechanical systems, electrostatic fields, quantum mechanics, and many...
Within the framework of AdS/CFT correspondence we considered large N limits of conformal field theories in d dimensions which described in terms of supergravity on the product of AdS space with a compact manifold. An important example of such correspondence is equivalence between N = 4 super Yang-Mills theory in four dimensions and Type IIB superstring theory on $AdS_5 × S^5$ [1]. The...
In quark-gluon plasma (QGP), at higher deconfinement temperatures $T \ge T_d$ the spontaneous generation of color magnetic fields, $b^3(T), b^8(T) \not = 0$ (3, 8 are color indexes), and usual magnetic field $b(T) \not = 0$ happens. Simultaneously, the Polyakov loop and/or algebraically related to it $A_0(T)$ condensate, which is solution to Yang-Mills imaginary time equations, ...
One of the simplest renormalizable extensions of the SM is the minimal neutrino extension of the Standard Model $\nu$MSM, proposed in 2005 [1, 2]. This modification introduces three righthanded neutrinos or heavy neutral leptons (HNL). The lightest sterile neutrino is identified as a dark matter particle. The other two sterile neutrinos are much heavier, with nearly identical masses, and are...
The Bohr’s Hamiltonian is one of the main cornerstones of the nuclear structure theory. It was derived by Bohr [1], treating the nucleus as a liquid spherical drop with uniform density and sharp surface, performing quadrupole vibrations with small amplitude. During such oscillations at any moment of time the nucleus attains an ellipsoidal shape, retaining its volume constant due to small...
We described the anomalous temperature behavior of the giant dielectric response and losses using the core-shell model for ceramic grains and modified Maxwell-Wagner approach. We assume that core shells and grain boundaries, which contain high concentration of space charge carriers due to the presence of graphite inclusions in the inter-grain space, can effectively screen weakly conductive...
Existing theoretical models of ferroelectric nanocomposites use the effective medium approximation to describe their dielectric and conductive properties. The most common effective medium models (Landau linear mixture approximation, Maxwell-Garnett model, Bruggeman model, etc.) may be invalid for dense nanocomposites when the volume fraction of ferroelectric inclusions exceeds 20-30%. We have...
DNA is a highly charged molecule that is neutralized by positively charged metal or molecular ions (counterions). The neutralization of DNA by these counterions induces various effects, including the formation of DNA-DNA contacts that lead to further condensation of the macromolecule. The effect of DNA condensation has been widely observed for highly charged counterions (≥3+). For divalent...
O. O. Boliasova$^{1,2}$ and V. N. Krivoruchko$^3$
$^1$State Research Institution «Kyiv Academic University»
36 Academician Vernadsky Boulevard, 03142, Kyiv, Ukraine,
$^2$G. V. Kurdyumov Institute for Metal Physics of the N.A.S. of Ukraine
36 Academician Vernadsky Boulevard, 03142, Kyiv, Ukraine, and
$^3$Donetsk Institute for Physics and Engineering named after O.O. Galkin of the NAS of...
Analytical model of a nonlinear magnetization wave (MW) propagating through one-dimensional antifer-romagnetic magnonic crystal comprised of two sorts of antiferromagnets (AFM) is proposed for supercritical mode when the MW velocity exceeds the critical velocity of MW in both antiferromagnets AFMs or at least in one of them. Both AFMs that comprise the magnonic crystal are assumed to be...
Contemporary research in defense technology focuses extensively on concealing various objects from infrared (IR) reconnaissance. Numerous camouflage coatings are available in the market, designed to mask IR radiation emitted by targets. Manufacturers often claim that these coatings significantly reduce the mean apparent temperature difference (ΔT) between the object and its background....
The Potts model with invisible states was introduced to explain discrepancies between theoretical predictions and experimental observations of phase transitions in some systems where Zq symmetry is spontaneously broken [1]. It differs from the ordinary q-state Potts model in that each spin, besides the usual q visible states, can be also in any of r so-called invisible states. Spins in an...
Temporal changes in the temperature and concentration dependences of the pH value in aqueous sodium chloride solutions contacting with atmospheric carbon dioxide have been studied experimentally. The measurements are carried out in a temperature interval of (294–323) K for ion concentrations corresponding to (180–1600) water molecules per sodium or chlorine ion.
The pH value for dilute...
Topologically non-trivial two-dimensional magnetization configurations (solitons in magnets), such as skyrmions and vortices, are very promising as information carriers for spintronics and magnonics. Skyrmions exhibit several well-known dynamic regimes, among them are breathing modes when the skyrmion radius changes, and rotational modes when the position of the skyrmion core fluctuates....
An analysis of the temperature dependences of thermal conductivity κ(Т) of composite materials - graphene-multilayer graphene, semiconductor composites Bi0.5Sb1.5Te3 and In0.53Ga0.47As, was carried out as well as a comparison of their temperature dependences of κ(Т) with the thermal conductivity of similar materials, which are formed by superlattices, nanowires and hybrid nanostructures. The...
M.S. Barabashko1, M.I. Bagatskii1, V.V. Sumarokov1, A.I. Krivchikov1,
A. Jeżowski2, D. Szewczyk2,3, Y. Horbatenko1
1B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine,
47 Nauky Ave., Kharkiv, 61103, Ukraine
2 W. Trzebiatowski Institute for Low Temperatures and Structure Research, Polish Academy of Sciences,
P.O. Box 1410, 50-950 Wroclaw, Poland
3Low...
Germanium-Tin (GeSn) films are a highly promising material for optoelectronic applications, owing to their tunable bandgap, light emission, and compatibility with silicon technology. As the Sn content in alloys increases, the band gap of GeSn alloy continuously decreases, transitioning from indirect to direct band structure and reducing the effective mass of both electrons and holes. Recent...
The adenosine 5’-triphosphate (ATP) and its derivatives, ADP and AMP, play crucial role in many processes. For example, cAMP (adenosine 3′,5′-cyclic monophosphate), acts as a key second messenger in numerous signal transduction pathways and regulates various cellular functions [1].
So description of conformer properties and structural geometry of ATP/AMP is required for developing of...
The results of a study of phonon heat transfer in two-dimensional and three-dimensional conductors with different cross-sections are presented. The problem is considered in the ballistic regime of phonon propagation and in the radiative approximation of phonon emission by a heater at a given temperature.
The most known problem in this field is the determination of heat fluxes and...
In the broad field of nanotechnology, polymer matrix-based nanocomposites have become a relevant area of modern development and research. This is due to their wide application in biomedicine, electrical/electronic/optoelectronic applications, and interest in fuel cells. The field of nanotechnology is one of the most popular areas of current research and development in nearly all technical...
To date, the most of metamaterials used in diverse applications (from nanooptics and plasmonics to mobile communication and biophysics) are periodic structures consisting of spatially arranged inclusions. In the theory of metamaterials, they are treated as homogeneous media, if their unit cell size $d$ (the lattice constant) is much smaller than the wavelength $\lambda$ of the incident...
