Dynamics of Vortex Pair in Radial Flow

The problem of vortex pair motion in two-dimensional plane radial flow is solved. Under certain conditions for flow parameters, the vortex pair can reverse its motion within a bounded region. The vortex-pair translational velocity decreases or increases after passing through the source/sink region, depending on whether the flow is diverging or converging, respectively. The rotational motion of two corotating vortexes in a quiescent environment transforms into motion along a logarithmic spiral in the presence of radial flow. The problem may have applications in astrophysics and geophysics.Comment: 13 pages, 9 figure

Three-dimensional localized coherent structures of surface turbulence. III Experiment and model validation

The paper continues a series of publications devoted to the 3D nonlinear localized coherent structures on the surface of vertically falling liquid films. The work is primarily focussed on experimental investigations. We study: (i) instabilities and transitions leading to 3D coherent structures; (ii) characteristics of these structures. Some nonstationary effects are also studied numerically. Our experimental results, as well as the results of other investigators, are in a good agreement with our theoretical and numerical predictions.Comment: 42 pages, 15 figure

A Dipole Vortex Model of Obscuring Tori in Active Galaxy Nuclei

The torus concept as an essential structural component of active galactic nuclei (AGN) is generally accepted. Here, the situation is discussed when the torus "twisting" by the radiation or wind transforms it into a dipole toroidal vortex which in turn can be a source of matter replenishing the accretion disk. Thus emerging instability which can be responsible for quasar radiation flares accompanied by matter outbursts is also discussed. The "Matreshka" scheme for an obscuring vortex torus structure capable of explaining the AGN variability and evolution is proposed. The model parameters estimated numerically for the luminosity close to the Eddington limit agree well with the observations.Comment: 17 pages, 11 figures, version of this paper is published in Astronomy Report

Congenital hyperinsulinism: clinical cases

Background. Congenital hyperinsulinism (CHI) is a hereditary disorder presenting with the hypersecretion of insulin by pancreatic beta cells and further development of hypoglycaemia. CHI is an orphan disease. According to the European sources, its incidence averages to 1:30,000– 1:50,000 newborns.Clinical Cases Description. This article describes two clinical CHI cases in girls. Case 1: a girl, born on 20.06.2017, was admitted to a paediatric unit of the Children’s Territorial Clinical Hospital for a seizure syndrome. CHI was diagnosed in the age of one month. At 5 months, the girl was confirmed a focal CHI with adenomatous focus localised in pancreatic head; a subtotal head resection has been performed facilitating a compensation. The girl was discharged in a satisfactory condition for a local residence outpatient follow-up. Case 2: the patient was diagnosed with CHI at 1 year 4 months upon admission to an endocrinology unit of the Children’s Territorial Clinical Hospital. The girl was redirected to the National Medical Research Centre for Endocrinology, where CHI was confirmed and indicated for a proglycem treatment. The child was followed-up at the Centre to adjust therapy. In July 2020, a fasting test with background proglycem therapy of 2.9 mg/kg/day (62.5 mg/day) revealed a medicated compensation. The patient was discharged with improvement for a resident endocrinologist follow-up with a recommendation of proglycem at a prescribed dosage upon vital indications.Conclusion. The clinical cases illustrate that, despite rarity and a marked heterogeneity, CHI can be timely diagnosed and properly treated in children. An adequate therapy can facilitate the disease compensation and prevent lifetime neurological complications

Digestive Disease Mortality Dynamics During New Coronavirus Infection Pandemic in Different Subjects of Russian Federation

Aim. An analysis of digestive disease mortality dynamics in different subjects of the Russian Federation in course of the new coronavirus infection pandemic.Key points. In most subjects of the Russian Federation, the first half of 2021 enduring the COVID-19 pandemic has witnessed a higher overall mortality from digestive diseases and from peptic ulcer, liver and pancreatic illnesses compared to the same period in 2020. This situation may have roots in both the adverse impact of coronavirus infection on pre-existing digestive diseases and shortages in providing specialty medical aid to gastroenterological patients during the pandemic. Improved outpatient care and remote counselling, as well as successful educational measures, may reduce gastroenterological disease-associated mortality.Conclusion. Most regions of Russia have registered a growing mortality from digestive diseases at the new coronavirus infection pandemic due to the SARS-CoV-2 adverse impact on illness progression, as well as imposed difficulties in providing specialty medical aid

Spiropyrans Containing the Reactive Substituents in the 2H-Chromene Moiety

Some spiropyrans containing functional substituents in the [2H]-chromene part of the molecule were synthesized and their photochromic properties in solution and solid state were investigated. The presence of the formyl group in the [2H]-chromene fragment enhances the possibility to show photochromic properties in solution

Landscape science: a Russian geographical tradition

The Russian geographical tradition of landscape science (landshaftovedenie) is analyzed with particular reference to its initiator, Lev Semenovich Berg (1876-1950). The differences between prevailing Russian and Western concepts of landscape in geography are discussed, and their common origins in German geographical thought in the late nineteenth and early twentieth centuries are delineated. It is argued that the principal differences are accounted for by a number of factors, of which Russia's own distinctive tradition in environmental science deriving from the work of V. V. Dokuchaev (1846-1903), the activities of certain key individuals (such as Berg and C. O. Sauer), and the very different social and political circumstances in different parts of the world appear to be the most significant. At the same time it is noted that neither in Russia nor in the West have geographers succeeded in specifying an agreed and unproblematic understanding of landscape, or more broadly in promoting a common geographical conception of human-environment relationships. In light of such uncertainties, the latter part of the article argues for closer international links between the variant landscape traditions in geography as an important contribution to the quest for sustainability

Study of a novel type of the optical modes in VCSELs

We study novel side-emitting modes in VCSEL microcavities. These modes correspond to π-shaped propagation along the mesa diameter, reflection from angled mesa walls and bottom Bragg reflector. We believe this study of π-modes is important for optimization of VCSEL design for improvement of efficiency