Aggregation kinetics at sedimentation: the impact of particles diffusion

We investigate the aggregation kinetics of sedimenting particles theoretically and numerically, using the advection-diffusion equation. Agglomeration, caused by both transport mechanisms (diffusion and advection), is important for small particles, like primary ash or soot particles in atmosphere, and large particles of equal or close size, where the advection mechanism is weak. For small Peclet numbers, which quantify the relative importance of diffusion and advection, we obtain the aggregation rates, as an expansion in Peclet numbers. For large Peclet numbers we use purely ballistic aggregation rates. Combining these results we obtain the rational approximant for the whole range of Peclet numbers. We also compute the aggregation rates by numerically solving the advection-diffusion equation. The results of the numerical simulations are in excellent agreement with the analytical theory for the studied Peclet numbers, varying by four orders of magnitude.Comment: 7 pages, 2 figures, 26 reference

Specifics of anticoagulation in combination with atrial fibrillation and chronic kidney disease

Due to the population aging and the accumulation of concomitant diseases, the prevalence of atrial fibrillation (AF) as the most common arrhythmia is increasing. On the other hand, 14% of the population has chronic kidney disease (CKD). These conditions are often combined with each other causing a prothrombogenic effect, which significantly increase the number of unfavorable outcomes such as thromboembolism, stroke, myocardial infarction and cardiovascular death. This is especially true for the last stages of CKD, the so-called end-stage renal disease with a glomerular filtration rate <29 ml/min/1,73 m2. Previously, the vitamin K antagonist warfarin was the central drug for anticoagulant therapy of AF + CKD combination, but in the last decade, direct oral anticoagulants became widely used. This article discusses the evidence base for using each of the anticoagulants in patients with AF+CKD combination compared with warfarin, including depending on the severity of glomerular filtration rate decrease

Use of an Analytical Theory for the Physical Libration of the Moon to Detect Free Nutation of the Lunar Core

© 2018, Pleiades Publishing, Ltd. A brief review of modern observational achievements and the theoretical basis of physical libration of the Moon is presented. Special attention is given to the inferred existence of a lunar core and determination of its parameters. The creation of a theory of physical libration of the Moon, which requires analyses of semi-empirical series of long-term laser observations and the use of the highly accurate DE421 dynamical ephemeris, is related to this. A large role in this area has been played by the analytical theory of physical libration of the Moon constructed by Yu.V. Barkin, which made it possible for the first time to derive parameters of the free nutation of the lunar core from observations. This paper is based on a talk given at the conference “Modern Astrometry 2017,” dedicated to the memory of K.V. Kuimov (Sternberg Astronomical Institute, Moscow State University, October 23–25, 2017)

Is anticoagulant therapy necessary after hospitalization with COVID-19 pneumonia?

The coronavirus disease 2019 (COVID-19) pandemic is associated with high virulence, mortality and healthcare burden around the world. One of its features is procoagulant activity, which leads to a high incidence of thromboembolic events in the lungs and other organs. Therefore, from the very onset of the moderate COVID-19, low molecular weight heparins began to be used as anticoagulants, which proved to have a beneficial effect on mortality and the disease course and were included in all guidelines. However, the question on anticoagulant therapy need after discharge from the hospital is controversial. The opinions of various medical professional communities on this issue are divided. In particular, some of them, including the Russian Ministry of Health guidelines recommend 30-45day anticoagulation using novel oral anticoagulants (dabigatran, rivaroxaban, apixaban), but other sources do not provide such recommendations. This review discusses the effectiveness of anticoagulant therapy after COVID-19, as well as the need to use stratification scales to assess this therapy

Structural and electronic properties of heterointerfaces composed of complex ferroelectric oxides

The reported study was funded by RFBR according to the research project № 18-32-00595

Electrical properties of heterointerfaces composed of complex ferroelectric oxides: an experimental investigation

The reported study was funded by RFBR according to the research project № 18-32-00595

Modeling of the physical selenocentric surface using modern satellite observations and harmonic analysis methods

© Published under licence by IOP Publishing Ltd. On the basis of satellite observations taken during "Apollo", "Clementine", "Kaguya", "LRO", "GRAIL", and "SMART-1" space missions a model of lunar physical surface of 18th order of expansion into a series of harmonic coefficients was constructed. In order to expand the data on relief into spherical functions a step-by-step regression was applied. All the constructed models included only significant elements. The regression analysis of the models of lunar relief for various expansion orders was carried out; as a result, it was determined that increase in order of expansion did not play a prominent role from a certain stage. The influence of model's overdetermined structure on values of the parameters determined was also investigated

Multi-parametric analysis of the lunar internal structure based on space data

© SGEM2017 All Rights Reserved. Numerous space agencies and powers have announced their plans on lunar exploration for the next years. The main purposes are preparation and creation of long-term scientific, technological, experimental, and industrial bases on the near side of the Moon and in the areas of the lunar poles for conducting scientific experiments and investigating lunar bowels. The American space agency (NASA) has published the most detailed for today map of the lunar South Pole. The new data has been collected by the “Lunar Reconnaissance Orbiter” (LRO) spacecraft which is currently travelling around the Earth’s artificial satellite’s polar orbit (i.e. orbit with 900 inclination). The spacecraft is moving 45 km above the lunar surface which is lower than in any of previous missions. This fact alongside with the high-quality equipment has allowed “LRO” to obtain the most detailed map of the polar area. Particularly, the spacecraft has managed to find traces of hydrogen in the South Pole craters. In the present work we are discussing geophysical parameters, geometric and dynamic compression of the liquid core and elastic mantle of the multi-layer Moon. The lunar internal structure, including the lunar liquid core, is considered; an analytical solution of Clairaut’s equation for determining geometrical compression of the two-layer Moon model is obtained; mathematical and bifurcation analyses of the solution for the problem’s physical parameters are conducted; the software for computer simulating of different radiuses, densities, and values of geometrical compression is developed. These estimates are necessary for free librations of the lunar layers investigations and for the development of lunar laser ranging and radio interferometry in the international cooperation of space powers in the fields of both observations and processing and interpretation of observational data. Such investigations require development of adequate theoretical provision for modern technologies. In the present work relativistic effects of the Earth-Moon system rotation and the latest achievements in geophysics and selenophysics are taken into account

The analytical and numerical approaches to the theory of the Moon's librations: Modern analysis and results

© 2017 COSPAR Observing physical librations of celestial bodies and the Moon represents one of the astronomical methods of remotely assessing the internal structure of a celestial body without conducting expensive space experiments. The paper contains a review of recent advances in studying the Moon's structure using various methods of obtaining and applying the lunar physical librations (LPhL) data. In this article LPhL simulation methods of assessing viscoelastic and dissipative properties of the lunar body and lunar core parameters, whose existence has been recently confirmed during the seismic data reprocessing of “Apollo” space mission, are described. Much attention is paid to physical interpretation of the free librations phenomenon and the methods for its determination. In the paper the practical application of the most accurate analytical LPhL tables (Rambaux and Williams, 2011) is discussed. The tables were built on the basis of complex analytical processing of the residual differences obtained when comparing long-term series of laser observations with the numerical ephemeris DE421. In the paper an efficiency analysis of two approaches to LPhL theory is conducted: the numerical and the analytical ones. It has been shown that in lunar investigation both approaches complement each other in various aspects: the numerical approach provides high accuracy of the theory, which is required for the proper processing of modern observations, the analytical approach allows to comprehend the essence of the phenomena in the lunar rotation, predict and interpret new effects in the observations of lunar body and lunar core parameters

Analysis of orbital theories for the construction of the numerical theory of the lunar physical librations

© Published under licence by IOP Publishing Ltd. When using the numerical approach to construct the theory of physical libration of the Moon, it is necessary to solve the problem of comparing the numerical and analytical theories of lunar orbital motion. During these studies, the impact on the parameters of physical libration from the Moon's center of mass motion is determined. The paper contains the results of determining the effects caused by distinction in the position of lunar center of mass whose location is obtained according to two various lunar orbital theories. The analytical theory by Gutzwiller and Schmidt [1] constructed within the main problem of the Moon's motion and DE432 numerical theory taking into account a large number of factors, that extend beyond the main issue and that would be complicated or even impossible to consider when obtaining the analytical solution, are compared. Some reductions had been carried out in order to bring both theories to a unified reference system. Then the positions of the Moon's center of mass obtained in those theories were compared at an interval of 800 years. As a result, it was established that the amplitude of residual differences at the interval did not exceed 80 arc seconds in longitude and 10 arc seconds in latitude. The main reason for the obtained differences is neglecting planetary perturbations in the analytical theory. Other effects to distinguish the numerical theory from the analytical one are: motion of plane of the ecliptic, the Earth's and Moon's flattening, tidal effects etc. Those effects also cause the difference between the theories but slightly