179 research outputs found
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 kolmogorovβwiener 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 [3β6] we proposed to use the
KolmogorovβWiener 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 xΒΌ0-
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 kolmogorovβwiener 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 KolmogorovβWiener filter may be applied to prediction of stationary processes. So, it is of interest to investigate the possibility of the KolmogorovβWiener 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 120β1200 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 2β300 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 726β732 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
Introducing Learning Creative Mathematical Activity for Students in Extra Mathematics Teaching
ΠΠΊΡΠΈΠ²Π½ΠΎΡΡΡ ΠΊΠ°Π»Π»ΠΈΠΊΡΠ΅ΠΈΠ½-ΠΊΠΈΠ½ΠΈΠ½ΠΎΠ²ΠΎΠΉ ΠΈ ΡΠ΅Π½ΠΈΠ½-Π°Π½Π³ΠΈΠΎΡΠ΅Π½Π·ΠΈΠ½ΠΎΠ²ΠΎΠΉ ΡΠΈΡΡΠ΅ΠΌ ΠΊΡΠΎΠ²ΠΈ Π½ΠΎΠ²ΠΎΡΠΎΠΆΠ΄Π΅Π½Π½ΡΡ Ρ Π³ΠΈΠΏΠΎΠΊΡΠΈΡΠ΅ΡΠΊΠΈ-ΠΈΡΠ΅ΠΌΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠ½ΡΠ΅ΡΠ°Π»ΠΎΠΏΠ°ΡΠΈΠ΅ΠΉ
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: Ξ±1-proteinase inhibitor and Ξ±2-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 Ξ±1-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.ΠΠΈΡΠ»ΠΎΡΠΎΠ΄Π½Π°Ρ Π½Π΅Π΄ΠΎΡΡΠ°ΡΠΎΡΠ½ΠΎΡΡΡ Ρ Π½ΠΎΠ²ΠΎΡΠΎΠΆΠ΄Π΅Π½Π½ΡΡ
ΡΠΎΠΏΡΠΎΠ²ΠΎΠΆΠ΄Π°Π΅ΡΡΡ Π½Π°ΡΡΡΠ΅Π½ΠΈΠ΅ΠΌ ΡΠΎΠ½ΡΡΠ° ΡΠΎΡΡΠ΄ΠΎΠ², Π² ΡΠ΅Π³ΡΠ»ΡΡΠΈΠΈ ΠΊΠΎΡΠΎΡΠΎΠ³ΠΎ ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΡ ΡΡΠ°ΡΡΠΈΠ΅ ΠΊΠ°Π»Π»ΠΈΠΊΡΠ΅ΠΈΠ½-ΠΊΠΈΠ½ΠΈΠ½ΠΎΠ²Π°Ρ (ΠΠΠ‘) ΠΈ ΡΠ΅Π½ΠΈΠ½-Π°Π½Π³ΠΈΠΎΡΠ΅Π½Π·ΠΈΠ½ΠΎΠ²Π°Ρ ΡΠΈΡΡΠ΅ΠΌΡ (Π ΠΠ‘). ΠΠ°ΠΆΠ½ΡΠΌ ΠΏΠΎΠΊΠ°Π·Π°ΡΠ΅Π»Π΅ΠΌ Π³Π΅ΠΌΠΎΠ΄ΠΈΠ½Π°ΠΌΠΈΡΠ΅ΡΠΊΠΈΡ
Π½Π°ΡΡΡΠ΅Π½ΠΈΠΉ ΡΠ²Π»ΡΠ΅ΡΡΡ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ ΠΊΠ°Π»Π»ΠΈΠΊΡΠ΅ΠΈΠ½Π°, Π°Π½Π³ΠΈΠΎΡΠ΅Π½Π·ΠΈΠ½ΠΏΡΠ΅Π²ΡΠ°ΡΠ°ΡΡΠ΅Π³ΠΎ ΡΠ΅ΡΠΌΠ΅Π½ΡΠ° (ΠΠΠ€), Π° ΡΠ°ΠΊΠΆΠ΅ ΠΈΠ½Π³ΠΈΠ±ΠΈΡΠΎΡΠΎΠ² ΠΏΡΠΎΡΠ΅ΠΈΠ½Π°Π· - Ξ±1-ΠΏΡΠΎΡΠ΅ΠΈΠ½Π°Π·Π½ΠΎΠ³ΠΎ ΠΈΠ½Π³ΠΈΠ±ΠΈΡΠΎΡΠ° (Ξ±1-ΠΠ) ΠΈ Ξ±2-ΠΌΠ°ΠΊΡΠΎΠ³Π»ΠΎΠ±ΡΠ»ΠΈΠ½Π°. ΠΡΠΈ Π³ΠΈΠΏΠΎΠΊΡΠΈΡΠ΅ΡΠΊΠΈ-ΠΈΡΠ΅ΠΌΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠ½ΡΠ΅ΡΠ°Π»ΠΎΠΏΠ°ΡΠΈΠΈ Π΄ΠΎΠ½ΠΎΡΠ΅Π½Π½ΡΡ
ΠΈ Π΄Π΅ΡΠ΅ΠΉ I, II ΡΡΠ΅ΠΏΠ΅Π½ΠΈ Π½Π΅Π΄ΠΎΠ½ΠΎΡΠ΅Π½Π½ΠΎΡΡΠΈ ΡΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½Π° Π±ΠΎΠ»Π΅Π΅ Π²ΡΡΠ°ΠΆΠ΅Π½Π½Π°Ρ Π°ΠΊΡΠΈΠ²Π°ΡΠΈΡ ΠΠΠ‘ ΠΊΡΠΎΠ²ΠΈ ΠΏΠΎ ΡΡΠ°Π²Π½Π΅Π½ΠΈΡ Ρ Π ΠΠ‘. Π‘Π½ΠΈΠΆΠ΅Π½ΠΈΠ΅ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΠΈ Ξ±1-ΠΠ Π½Π°Π±Π»ΡΠ΄Π°Π΅ΡΡΡ Ρ 46% Π½ΠΎΠ²ΠΎΡΠΎΠΆΠ΄Π΅Π½Π½ΡΡ
II ΡΡΠ΅ΠΏΠ΅Π½ΠΈ Π½Π΅Π΄ΠΎΠ½ΠΎΡΠ΅Π½Π½ΠΎΡΡΠΈ, ΡΡΠΎ, ΠΊΠ°ΠΊ ΠΏΡΠ°Π²ΠΈΠ»ΠΎ, ΠΏΡΠΈΠ²ΠΎΠ΄ΠΈΡ ΠΊ Ρ
ΡΠΎΠ½ΠΈΠ·Π°ΡΠΈΠΈ ΠΏΠ°ΡΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΠΏΡΠΎΡΠ΅ΡΡΠ°. ΠΠ»Ρ ΠΏΡΠΎΠ³Π½ΠΎΠ·Π° Π½Π°ΡΡΡΠ΅Π½ΠΈΠΉ Π³Π΅ΠΌΠΎΠ΄ΠΈΠ½Π°ΠΌΠΈΠΊΠΈ ΠΈΠΌΠ΅Π΅Ρ Π·Π½Π°ΡΠ΅Π½ΠΈΠ΅ ΠΏΠΎΠ²ΡΡΠ΅Π½Π½Π°Ρ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ ΠΠΠ€.
ΠΠΊΠΎΠ½ΠΎΠΌΠΈΡΠ΅ΡΠΊΠ°Ρ ΠΎΡΠ΅Π½ΠΊΠ° ΠΏΡΠΎΠ²ΠΎΠ΄ΠΈΠ»Π°ΡΡ Π΄Π»Ρ ΠΎΠΏΡΠΈΠΌΠΈΠ·Π°ΡΠΈΠΈ ΠΌΠΎΡΡΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΉ Π² ΡΠ°Π±ΠΎΡΠ΅ ΠΎΡΠ΄Π΅Π»Π° ΡΠ΅ΡΠ΄Π΅ΡΠ½ΠΎ-ΡΠΎΡΡΠ΄ΠΈΡΡΠΎΠΉ Ρ
ΠΈΡΡΡΠ³ΠΈΠΈ ΠΠΠ ΠΊΠ°ΡΠ΄ΠΈΠΎΠ»ΠΎΠ³ΠΈΠΈ Π’ΠΠ¦ Π‘Π Π ΠΠΠ (Π³. Π’ΠΎΠΌΡΠΊ). ΠΠ΅ΠΎΠ±Ρ
ΠΎΠ΄ΠΈΠΌΠΎΡΡΡ Π°Π½Π°Π»ΠΈΠ·Π° ΡΡΠ΅ΠΏΠ΅Π½ΠΈ Π΄ΠΈΡΡΡΠ½ΠΊΡΠΈΠΈ ΠΌΠΈΠΎΠΊΠ°ΡΠ΄Π° ΠΎΠ±ΡΡΠ»ΠΎΠ²Π»ΠΈΠ²Π°Π΅ΡΡΡ Π²ΡΠ±ΠΎΡΠΎΠΌ ΠΎΠΏΡΠΈΠΌΠ°Π»ΡΠ½ΠΎΠΉ ΡΠ°ΠΊΡΠΈΠΊΠΈ Ρ
ΠΈΡΡΡΠ³ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ Π»Π΅ΡΠ΅Π½ΠΈΡ Π±ΠΎΠ»ΡΠ½ΡΡ
ΠΈΡΠ΅ΠΌΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΊΠ°ΡΠ΄ΠΈΠΎΠΌΠΈΠΎΠΏΠ°ΡΠΈΠ΅ΠΉ ΠΈΠ»ΠΈ Π²ΡΡΠ²Π»Π΅Π½ΠΈΡ ΠΏΡΠΎΡΠΈΠ²ΠΎΠΏΠΎΠΊΠ°Π·Π°Π½ΠΈΠΉ ΠΊ ΡΠ°ΠΊΠΎΠ²ΠΎΠΌΡ
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. Β© 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. ΠΠ-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 βQuantumβ' (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)
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