Meteor trail drift research based on baseline observations

We analyze the results of a rare long-lived quasisymmetric ellipsoidal-annular meteor trail recorded on November 18, 2017 by two optical all-sky cameras, spaced at a distance of 150 km. The analysis is based on astrometric processing results with the use of baseline measurement methods. We determine spatial-kinematic characteristics of the meteor trail, and find features of its evolution. The ignition and extinction heights of the meteor were in the range 75–120 km. The estimate of the meteor brightness gives the absolute magnitude value of about –7.3m. It is shown that the distribution of all parts of the long-lived meteor trail occurs in the same plane at a height of ~90 km at a speed of ~320 m/s and, apparently, cannot be a consequence of an air mass movement. The total time of the meteor trail observation was more than 30 min. We offer possible explanations for the results obtained in the context of upper atmosphere processes

First results of absolute measurements of solar flux at the Irkutsk Incoherent Scatter Radar (IISR)

The Irkutsk Incoherent Scatter Radar (IISR) allows us to carry out passive radio observations of the Sun and other powerful radio sources. We describe a method for absolute measurements of spectral flux density of solar radiation at IISR. The absolute measurements are meant to determine the flux density in physical units [W·m–2·Hz–1]. The IISR antenna is a horn with frequency beam steering, therefore radio sources can be observed at different frequencies. Also there is a polarization filter in the antenna aperture, which passes only single (horizontal) polarization. To acquire flux density absolute values, the IISR receiver is calibrated by the Cygnus-A radiation. Since the Sun’s position in the IISR antenna pattern is determined by a frequency differing from the Cygnus-A observation frequency, we perform an additional calibration of the frequency response in the 154–162 MHz operation frequency range, using the background sky noise. The solar disk size is comparable with the main beam width in the north—south direction, hence the need to take into account the shape of the brightness distribution in the operation frequency range. The average flux density of the quiet-Sun radiation was ~5 sfu (solar flux units, 10–22 W·m–2·Hz–1) at the 161 MHz frequency

Spectral and photometric characteristics of mid-latitude auroras during the magnetic storm of March 17, 2015

We study the spatiotemporal dynamics of mid-latitude aurora from observations in the south of Eastern Siberia during St. Patrick’s severe geomagnetic storm on March 17, 2015. We perform a morphological analysis of characteristics of the observed auroras. A preliminary conclusion is drawn that the analyzed event is the result of the manifestation of mid-latitude auroras of two types (type “d” and SAR arc) and ordinary aurora observed at the northern horizon. The maximum intensity of the dominant emission [OI] at 630.0 nm (~14 kR) allows this mid-latitude aurora to be attributed to the extreme auroras occurring in mid-latitudes, which is second only to the November 20, 2003 superstorm (~19 kR)

Population genomics of post-glacial western Eurasia.

Western Eurasia witnessed several large-scale human migrations during the Holocene <sup>1-5</sup> . Here, to investigate the cross-continental effects of these migrations, we shotgun-sequenced 317 genomes-mainly from the Mesolithic and Neolithic periods-from across northern and western Eurasia. These were imputed alongside published data to obtain diploid genotypes from more than 1,600 ancient humans. Our analyses revealed a 'great divide' genomic boundary extending from the Black Sea to the Baltic. Mesolithic hunter-gatherers were highly genetically differentiated east and west of this zone, and the effect of the neolithization was equally disparate. Large-scale ancestry shifts occurred in the west as farming was introduced, including near-total replacement of hunter-gatherers in many areas, whereas no substantial ancestry shifts happened east of the zone during the same period. Similarly, relatedness decreased in the west from the Neolithic transition onwards, whereas, east of the Urals, relatedness remained high until around 4,000 BP, consistent with the persistence of localized groups of hunter-gatherers. The boundary dissolved when Yamnaya-related ancestry spread across western Eurasia around 5,000 BP, resulting in a second major turnover that reached most parts of Europe within a 1,000-year span. The genetic origin and fate of the Yamnaya have remained elusive, but we show that hunter-gatherers from the Middle Don region contributed ancestry to them. Yamnaya groups later admixed with individuals associated with the Globular Amphora culture before expanding into Europe. Similar turnovers occurred in western Siberia, where we report new genomic data from a 'Neolithic steppe' cline spanning the Siberian forest steppe to Lake Baikal. These prehistoric migrations had profound and lasting effects on the genetic diversity of Eurasian populations

Multiwavelength behaviour of the blazar 3C 279: decade-long study from γ-ray to radio

We report the results of decade-long (2008–2018) γ-ray to 1 GHz radio monitoring of the blazar 3C 279, including GASP/WEBT, Fermi and Swift data, as well as polarimetric and spectroscopic data. The X-ray and γ-ray light curves correlate well, with no delay ≳ 3 h, implying general cospatiality of the emission regions. The γ-ray–optical flux–flux relation changes with activity state, ranging from a linear to a more complex dependence. The behaviour of the Stokes parameters at optical and radio wavelengths, including 43 GHz Very Long Baseline Array images, supports either a predominantly helical magnetic field or motion of the radiating plasma along a spiral path. Apparent speeds of emission knots range from 10 to 37c, with the highest values requiring bulk Lorentz factors close to those needed to explain γ-ray variability on very short time-scales. The Mg ii emission line flux in the ‘blue’ and ‘red’ wings correlates with the optical synchrotron continuum flux density, possibly providing a variable source of seed photons for inverse Compton scattering. In the radio bands, we find progressive delays of the most prominent light-curve maxima with decreasing frequency, as expected from the frequency dependence of the τ = 1 surface of synchrotron self-absorption. The global maximum in the 86 GHz light curve becomes less prominent at lower frequencies, while a local maximum, appearing in 2014, strengthens toward decreasing frequencies, becoming pronounced at ∼5 GHz. These tendencies suggest different Doppler boosting of stratified radio-emitting zones in the jet.First author draf

Interferometric observation of Cygnus-А discrete radiosource scintillations at Irkutsk Incoherent Scatter radar

We propose a new method for analyzing data from the Irkutsk Incoherent Scatter Radar. The method allows us to accomplish interferometric observation of discrete cosmic radio source characteristics. In this study, we analyze ionospheric scintillations of the radio source Cygnus-A. Observations were made in 2013 during regular radar sessions within 5–15 days for different seasons; the effective time of observation was 15–30 minutes per day. For interferometric analysis, the properties of correlation (coherence) coefficient of two independent recording channels were used. The statistical analysis of data from the independent channels allows us to construct two-dimensional histograms of radio source brightness distribution with a period of 18 s and to determine parameters (the maximum position and the histogram width) representing position and angular size of the radio source for each histogram. It is shown that the change of statistical characteristics does not correlate with fluctuations in power (scintillations) of the signal induced by radio wave propagation through ionospheric irregularities

Registering upper atmosphere parameters in East Siberia with Fabry–Perot Interferometer KEO Scientific “Arinae”

We describe the Fabry—Perot interfero-meter designed to study Earth’s upper atmosphere. We propose a modification of the existing data processing method for determining the Doppler shift and Doppler widening and also for separating the observed line intensity and the background intensity. The temperature and wind velocity derived from these parameters are compared with physical characteristics obtained from modeling (NRLMSISE-00, HWM14). We demonstrate that the temperature is determined from the oxygen 630 nm line irrespective of the hydroxyl signal existing in interference patterns. We show that the interferometer can obtain temperature from the oxygen 557.7 nm line in case of additional calibration of the device. The observed wind velocity mainly agrees with model data. Night variations in the red and green oxygen lines quite well coincide with those in intensities obtained by devices installed nearby the interferometer

Modern heating facility for research into the mid-latitude ionosphere

© Meandros Medical and Dental Journal. The development of new devices for research in physics of the upper atmosphere and near-Earth space, which can be used to carry out controlled experiments on the modification of the ionosphere by powerful short-wave radiation, is an urgent task of modern solar-terrestrial physics, space weather, operation of satellite constellations in near-Earth space, radio communications, and radar. The paper describes a modern heating facility, created within the framework of the National Heliogeophysical Complex of the Russian Academy of Sciences. We review the tasks facing the heater, discuss its main technical characteristics, and describe the capability of the observational infrastructure surrounding the heating facility. The paper justifies the long-term benefits of the development of a heating facility at middle latitudes of Eastern Siberia, which can radiate in a frequency range 2.5-6.0 MHz with an effective power of the order of several hundred megawatts. It is important that the heater will be surrounded by such multifunctional instruments as the modern incoherent scatter radar, mesostratospheric lidar, observational systems that can provide a wide range of possibilities for diagnosing artificial plasma disturbances and artificial airglow structures

Врожденные портосистемные шунты: опыт хирургического лечения

Congenital porto-caval shunts are rare and may have a different morphological structure (intra- and extrahepatic shunts, with or without portal blood flow). The main method of treating patients with this pathology is endovascular shunt occlusion. However, in some cases, this method is ineffective. The article contains a description of six clinical examples of surgical treatment of congenital porto-systemic shunts in children. In the diagnosis of congenital portosystemic shunts, the leading role belongs to Doppler ultrasound, multislice computed tomography, and angiography. The indication for surgical treatment was the anatomical features of the shunt, which makes endovascular occlusion technically impossible. In one observation a wide Arantian duct was diagnosed, its open ligation was performed. In another case, the portal vein emptied directly into an aneurysmal dilatation, performed reconstructive plastic surgery on the vessels of the portal vein. In the next observation, a pronounced retrograde blood flow was determined along the dilated inferior mesenteric vein, blood was discharged through the sacral plexus into the internal iliac vein. The left internal iliac vein was isolated and ligated, the dysplastic inferior mesenteric vein was ligated and partially removed. In 2 patients, the portal vein flowed directly into the inferior vena cava in the area of aneurysmal expansion; an operation was performed open ligation of the shunt. In one observation, a deep hypoplasia of the intrahepatic branches of the portal vein was diagnosed, and therefore the restoration of portal blood flow after the closure of the shunt is impossible. The child was sent to decide on a liver transplant. Each case of congenital porto-caval shunts is unique. The surgeon determines the tactics directly during the operation, depending on the morphological structure of the organs, since the preoperative examination does not always give an unambiguous idea.Врожденные портокавальные шунты встречаются редко и могут иметь различную морфологическую структуру (внутри- и внепеченочные шунты, с наличием или отсутствием портального кровотока). Основной метод лечения пациентов с данной патологией эндоваскулярная окклюзия шунта. Однако в некоторых случаях подобный метод оказывается неэффективным. В статье содержится описание шести клинических примеров хирургического лечения врожденных порто-системных шунтов у детей. В диагностике врожденных порто-системных шунтов ведущая роль принадлежит ультразвуковому исследованию с допплерографией, мультиспиральной компьютерной томографии, ангиографии. Показанием к оперативному лечению стали анатомические особенности шунта, делающие эндоваскулярную окклюзию технически невозможной. В одном наблюдении диагностирован широкий аранциев проток, была выполнена его открытая перевязка. В другом случае воротная вена впадала непосредственно в аневризматическое расширение, выполнена реконструктивно-пластическая операция на сосудах воротной вены. В следующем наблюдении определялся выраженный ретроградный кровоток по расширенной нижней брыжеечной вене, сброс крови через сакральное сплетение во внутреннюю подвздошную вену. Произведено выделение левой внутренней подвздошной вены и ее перевязка, дисплазированная нижняя брыжеечная вена перевязана и частично удалена. У двух пациентов воротная вена впадала непосредственно в нижнюю полую вену в области аневризматического расширения, проведена операция открытая перевязка шунта. В одном наблюдении диагностирована глубокая гипоплазия внутрипеченочных ветвей воротной вены, в связи с чем восстановление портального кровотока после закрытия шунта невозможно. Ребенок был направлен для решения вопроса о трансплантации печени. Каждый случай врожденных портокавальных шунтов уникален. Хирург определяет тактику непосредственно в ходе операции в зависимости от морфологического строения органов, поскольку предоперационное обследование не всегда дает однозначное представление