Generalization of the Grad method in plasma physics

The Grad method is generalized based on the Bogolyubov idea of the functional hypothesis for states at the end of relaxation processes in a system. The Grad problem (i.e., description of the Maxwell relaxation) for a completely ionized spatially uniform two-component electron-ion plasma is investigated using the Landau kinetic equation. The component distribution functions and time evolution equations for parameters describing the state of a system are calculated, and corrections are obtained to the known results in a perturbation theory in a small electron-to-ion mass ratio.Comment: 10 pages, 2 table

On relaxation phenomena in a two-component plasma

The relaxation of temperatures and velocities of the components of a quasi-equilibrium two-component homogeneous completely ionized plasma is investigated on the basis of a generalization of the Chapman-Enskog method applied to the Landau kinetic equation. The generalization is based on the functional hypothesis in order to account for the presence of kinetic modes of the system. In the approximation of a small difference of the component temperatures and velocities, it is shown that relaxation really exists (the relaxation rates are positive). The proof is based on the arguments that are valid for an arbitrary two-component system. The equations describing the temperature and velocity kinetic modes of the system are investigated in a perturbation theory in the square root of the small electron-to-ion mass ratio. The equations of each order of this perturbation theory are solved with the help of the Sonine polynomial expansion. Corrections to the known Landau results related to the distribution functions of the plasma and relaxation rates are obtained. The hydrodynamic theory based on these results should take into account a violation of local equilibrium in the presence of relaxation processes.Comment: 18 page

On the accuracy of some polynomial approximations for the kolmogorov–wiener filter weight function

The problem of telecommunication traffic prediction is important for telecommunications and cyber security, see [1]. In paper [2] telecommunication traffic is described as a continuous stationary random process with a power-law structure function. In the framework of this model in papers [3–6] we proposed to use the Kolmogorov–Wiener filter for telecommunication traffic prediction. An approximate solution of the corresponding integral equation for the unknown weight function was obtained on the basis of the truncated polynomial expansion method

Thermal expansion and polarization of (1-x)PNNxPT solid solutions

The paper presents the results of detailed studies of the thermal expansion of (1-x)PbNi1/3Nb2/3O3-xPbTiO3 solid solutions with x¼0- 0.8. The anomalous and lattice contributions to deformation and the thermal expansion coefficient are analyzed and the mean square polarization Pd is determined. The results obtained are discussed within the framework of the thermodynamic theory and the Landau 2-4-6 coefficients for solid solutions are estimate

On the discrete kolmogorov–wiener filter for the one-point prediction of exponentially smoothed heavy-tail processes

The prediction of telecommunication traffic is an important problem for telecommunications and cyber security, see a detailed description in [1]. There are a plenty of different (and rather sophisticated) approaches to traffic prediction, see [1]. The telecommunication traffic is considered to be stationary random process in a couple of models, and, as is known, such a simple algorithm as the Kolmogorov–Wiener filter may be applied to prediction of stationary processes. So, it is of interest to investigate the possibility of the Kolmogorov–Wiener filter application to heavy-tail process prediction, because traffic in telecommunication systems with data packet transfer in considered to be a heavy-tail random process, see [2,3]. Out previous paper [4] is devoted to the corresponding problem

Investigation of the thermal expansion and heat capacity of the CaCu3Ti4O12 ceramics

The thermal expansion of the CaCu3Ti4O12 ceramics has been measured over a wide temperature range 120–1200 K. The high quality of the samples under study has been confirmed by good agreement of the results of measurements of the heat capacity in the range 2–300 K and in the vicinity of the phase transition of magnetic nature at 25 K with the data for the single crystal. No anomalies in the thermal expansion that can be associated with the phase transition at 726–732 K assumed by other investigators have been found. The influence exerted on the thermal expansion by the heat treatment of the sample in a helium atmosphere and in air has been investigated

Активность калликреин-кининовой и ренин-ангиотензиновой систем крови новорожденных с гипоксически-ишемической энцефалопатией

Oxygen insufficiency in newborns is associated with disturbed vascular tone, which are regulated by kallikrein-kinin (KKS) and renin-angiotensin systems (RAS).Important index of hemodynamic disturbances is the activity of kallikrein, of angiotensin-converting enzyme (ACE) and also inhibitors of proteinases: α1-proteinase inhibitor and α2-macroglobulin. In hypoxic-ischemic encephalopathy of mature newborns and children of the I, II premature degrees , blood KKS activity is increased in comparison with RAS. Decreased activity of α1-proteinase inhibitor is seen in 46% of premature infants of II degree which usually leads to chronic pathologic process. The increased activity of ACE is important for preventing hemodynamic disturbances.Кислородная недостаточность у новорожденных сопровождается нарушением тонуса сосудов, в регуляции которого принимают участие калликреин-кининовая (ККС) и ренин-ангиотензиновая системы (РАС). Важным показателем гемодинамических нарушений является активность калликреина, ангиотензинпревращающего фермента (АПФ), а также ингибиторов протеиназ - α1-протеиназного ингибитора (α1-ПИ) и α2-макроглобулина. При гипоксически-ишемической энцефалопатии доношенных и детей I, II степени недоношенности установлена более выраженная активация ККС крови по сравнению с РАС. Снижение активности α1-ПИ наблюдается у 46% новорожденных II степени недоношенности, что, как правило, приводит к хронизации патологического процесса. Для прогноза нарушений гемодинамики имеет значение повышенная активность АПФ. Экономическая оценка проводилась для оптимизации морфологических исследований в работе отдела сердечно-сосудистой хирургии НИИ кардиологии ТНЦ СО РАМН (г. Томск). Необходимость анализа степени дисфункции миокарда обусловливается выбором оптимальной тактики хирургического лечения больных ишемической кардиомиопатией или выявления противопоказаний к таковому

Spin state crossover in Co3BO5

We have investigated the spin and oxidation states of Co in Co3BO5 using x-ray magnetic circular dichroism (XMCD) and dc magnetic susceptibility measurements. At low temperatures, XMCD experiments have been performed at the Co K-edge in Co3BO5 and Co2FeBO5 single crystals in the fully ferrimagnetically ordered phase. The Co (K-edge) XMCD signal is found to be related to the Co2+ magnetic sublattices in both compounds, providing strong experimental support for the low-spin (LS) Co3+ scenario. The paramagnetic susceptibility is highly anisotropic. An estimation of the effective magnetic moment in the temperature range 100-250 K correlates well with two Co2+ ions in the high-spin (HS) state and some orbital contribution, while Co3+ remains in the LS state. The crystal structure of the Co3BO5 single crystal has been solved in detail at the T range 296-703 K. The unit cell parameters and volume show anomalies at 500 and 700 K. The octahedral environment of the Co4 site strongly changes with heating. The generalized gradient approximation with Hubbard U correction calculations have revealed that, at low-temperatures, the system is insulating with a band gap of 1.4 eV, and the Co2+ ions are in the HS state, while Co3+ are in the LS state. At high temperatures (T > 700 K), the charge ordering disappears, and the system becomes metallic with all Co ions in 3d7 electronic configuration and HS state. © 2021 American Physical Society.We acknowledge many inspirational discussions on the topic of this paper with the late Natalia Ivanova and Leonard Bezmaternykh. The authors acknowledge A. Ney for allowing us to use the XANES spectrum of film. We are grateful to the Russian Foundation for Basic Research (Project No. 20-02-00559) and President Council on Grants (Project No. МК-2339.2020.2) for supporting this paper. This paper was carried out within the state assignment of the Russian Ministry of Science and High Education via program “Quantum”' (No. AAAA-A18-118020190095-4). We also acknowledge support by Russian Ministry of Education and Science via Contract No. 02.A03.21.0006. We acknowledge financial support from the Spanish Ministry of Economy, Industry and Competitiveness (MINECO, Grant No. MAT2017-83468-R) and from the regional Government of Aragon (E12-20R RASMIA project)