Generation of powerful terahertz emission in a beam-driven strong plasma turbulence

Generation of terahertz electromagnetic radiation due to coalescence of upper-hybrid waves in the long-wavelength region of strong plasma turbulence driven by a high-current relativistic electron beam in a magnetized plasma is investigated. The width of frequency spectrum as well as angular characteristics of this radiation for various values of plasma density and turbulence energy are calculated using the simple theoretical model adequately describing beam-plasma experiments at mirror traps. It is shown that the power density of electromagnetic emission at the second harmonic of plasma frequency in the terahertz range for these laboratory experiments can reach the level of 1 ${MW/cm}^3$ with 1% conversion efficiency of beam energy losses to electromagnetic emission

Second harmonic electromagnetic emission of a turbulent magnetized plasma driven by a powerful electron beam

The power of second harmonic electromagnetic emission is calculated for the case when strong plasma turbulence is excited by a powerful electron beam in a magnetized plasma. It is shown that the simple analytical model of strong plasma turbulence with the assumption of a constant pump power is able to explain experimentally observed bursts of electromagnetic radiation as a consequence of separate collapse events. It is also found that the electromagnetic emission power calculated for three-wave interaction processes occurring in the long-wavelength part of turbulent spectrum is in order-of-magnitude agreement with experimental results

Impact of growing conditions on the gum properties of different genotypes of guar (Cyamopsis tetragonoloba (L.) Taub.)

Galactomannan (gum), a water-soluble polysaccharide, is widely used as a gelling agent in liquids, including in the oil and gas industry for hydraulic fracturing. The most effective source of this valuable plant material is seeds of guar (Cyamopsis tetragonoloba (L.) Taub.), a legume crop new for Russia. Although in recent years progress has been made in the selection of guar varieties adapted to the conditions of the Russian Federation, the question of the most appropriate region for the cultivation of this crop remains open. The purpose of the study was to investigate how a region and technology of guar cultivation can affect the main indicators of the final target product: the content and viscosity of guar gum extracted from the seeds of various guar genotypes. To understand this, ecogeographical tests of 13 guar accessions from the VIR collection were conducted at the experimental stations of the Vavilov Institute (VIR), where climatic conditions correspond to the temperature requirements of the crop. To compare the properties of gum extracted from the seeds of various genotypes, a fast-tracked laboratory method was suggested allowing gum extracts to be obtained for assessing their viscosity. The method allows fast screening of the breeding material and selecting guar genotypes with beneficial properties of guar gum which are in demand by the oil industry. Applying the fast laboratory method for assessing the properties of gum in seeds of 13 guar varieties showed that the content and viscosity of gum of the same variety vary greatly depending on growing conditions. The same set of 13 guar accessions was grown in 2018 at the Volgograd, Astrakhan, Dagestan and Kuban VIR experimental stations. As a result, the maximum viscosity values were obtained for the seeds reproduced at the Astrakhan region, where the guar was grown on irrigated lands. On the other hand, the maximum gum content in the seeds of all accessions was recorded when they were grown in the Volgograd region. The results showed that the guar gum extracted from seeds of guar plants grown in the Russian Federation can be used as a gelling agent in the processes of intensification of oil production by the method of hydraulic fracturing. This experience is new to the Russian Federation

Опыт диагностики и лечения болезни Кавасаки в клинике Санкт-Петербургского государственного педиатрического медицинского университета и Д етской городской больнице №1 Санкт-Петербурга

Kawasaki disease (KD) is acute systemic vasculitis of unknown etiology. Approximately 20–25% of untreated patients develop coronary artery changes with a range of severity from asymptomatic coronary artery dilatation to giant coronary artery aneurysms with thrombosis, myocardial infarction, and sudden death. To date there is no official data on the incidence of KD in Russia. In Russia, the disease is not enough known now to a wide circle of physicians and often masks other more common diseases. Since 2010, the detection rate of KD has dramatically increased in Saint-Petersburg.Objective: to analyze the experience in diagnosing and treating KD in two largest hospitals of Saint Petersburg.Patients and methods. The retrospective study included data on 30 children (18 boys, 12 girls) who were hospitalized with a diagnosis of KD in the Saint-Petersburg State Pediatric Medical University Clinic and Children’s Hospital One (Saint Petersburg) between January 2011 and September 2016. Data are represented by median and extreme values. The age of the children was 2.8 (0.2; 4.6) years; of them 5 (16.7%) patients were under the age of 1 year. The children were hospitalized on 5 (1; 14) days of disease onset; KD was diagnosed on 9 (3; 52) day of the disease.Results. Immediately after diagnosis, 27 (90%) children received aspirin. In early stages (before 10 days of the disease), intravenous immunoglobulin (IVIG) therapy was performed in 15 (50%) children, one of them received IVIG before disease day 5 (on day 3), but without effect. On disease days 11-20 (immediately after diagnosis), 10 (33.3%) children were prescribed with IVIG; thereafter fever was abolished in all the patients. Their body temperature became normal on day 11 (6; 23). Ultrasonography revealed coronary artery lesions in 13 (43.3%) patients. Out of the 30 children followed up, one baby who fell ill at the age of 3 months and received IVIG died on day 30 of the disease.Conclusion. Currently, there continues to be a delayed diagnosis of KD. IVIG therapy was effective, especially in cases of timely diagnosis. It is necessary to increase awareness of KD among clinicians and ultrasound diagnosticians.Болезнь Кавасаки (БК) – остро протекающий системный васкулит неизвестной этиологии. Примерно у 20–25% не получивших лечения больных развиваются изменения коронарных артерий различной степени тяжести – от бессимптомной дилатации до гигантских аневризм, тромбоза, инфаркта миокарда и внезапной смерти. До настоящего времени официальных данных о заболеваемости БК в России нет. В нашей стране БК недостаточно известна широкому кругу врачей и часто проходит под маской других более распространенных заболеваний. В Санкт-Петербурге после 2010 г. резко возросла выявляемость БК.Цель исследования – проанализировать опыт диагностики и лечения БК в двух крупных стационарах Санкт-Петербурга.Пациенты и методы. В ретроспективное исследование были включены данные о 30 детях (18 мальчиков, 12 девочек), находившихся на стационарном лечении с диагнозом БК в клинике Санкт-Петербургского государственного педиатрического медицинского университета и Детской городской больнице №1 Санкт-Петербурга с января 2011 г. по сентябрь 2016 г. Данные представлены медианой и крайними значениями. Возраст детей составил 2,8 [0,2; 4,6] года, из них 5 (16,7%) пациентов были в возрасте до 1 года. Дети были госпитализированы на 5-е [1; 14] сутки болезни, диагноз БК установлен на 9-й [3; 52] день болезни.Результаты. Сразу после установления диагноза получили аспирин 27 детей (90%). В ранние сроки (до 10-го дня болезни) терапия внутривенным иммуноглобулином (ВВИГ) проводилась у 15 (50%) пациентов, из них 1 получил ВВИГ ранее 5-го дня болезни (на 3-й день), однако без эффекта. На 11–20-й день болезни (сразу после установления диагноза) ВВИГ назначен 10 (33,3%) детям, после чего лихорадка была купирована у всех пациентов. Температура тела нормализовалась на 11-й [6; 23] день. Поражение коронарных артерий при УЗИ выявлено у 13 (43,3%) пациентов. Из 30 находившихся под наблюдением детей у 1 ребенка, заболевшего в возрасте 3 мес и получившего ВВИГ на 30-й день болезни, зафиксирован летальный исход.Выводы. В настоящее время БК продолжает диагностироваться с опозданием. Терапия ВВИГ была эффективной, особенно в случаях своевременного установления диагноза. Необходимо повышение осведомленности клиницистов и врачей ультразвуковой диагностики о БК

Experience in the diagnosis and treatment of Kawasaki disease in the Saint-Petersburg State Pediatric Medical University Clinic and Saint Petersburg City Children’s Hospital One

Kawasaki disease (KD) is acute systemic vasculitis of unknown etiology. Approximately 20–25% of untreated patients develop coronary artery changes with a range of severity from asymptomatic coronary artery dilatation to giant coronary artery aneurysms with thrombosis, myocardial infarction, and sudden death. To date there is no official data on the incidence of KD in Russia. In Russia, the disease is not enough known now to a wide circle of physicians and often masks other more common diseases. Since 2010, the detection rate of KD has dramatically increased in Saint-Petersburg.Objective: to analyze the experience in diagnosing and treating KD in two largest hospitals of Saint Petersburg.Patients and methods. The retrospective study included data on 30 children (18 boys, 12 girls) who were hospitalized with a diagnosis of KD in the Saint-Petersburg State Pediatric Medical University Clinic and Children’s Hospital One (Saint Petersburg) between January 2011 and September 2016. Data are represented by median and extreme values. The age of the children was 2.8 (0.2; 4.6) years; of them 5 (16.7%) patients were under the age of 1 year. The children were hospitalized on 5 (1; 14) days of disease onset; KD was diagnosed on 9 (3; 52) day of the disease.Results. Immediately after diagnosis, 27 (90%) children received aspirin. In early stages (before 10 days of the disease), intravenous immunoglobulin (IVIG) therapy was performed in 15 (50%) children, one of them received IVIG before disease day 5 (on day 3), but without effect. On disease days 11-20 (immediately after diagnosis), 10 (33.3%) children were prescribed with IVIG; thereafter fever was abolished in all the patients. Their body temperature became normal on day 11 (6; 23). Ultrasonography revealed coronary artery lesions in 13 (43.3%) patients. Out of the 30 children followed up, one baby who fell ill at the age of 3 months and received IVIG died on day 30 of the disease.Conclusion. Currently, there continues to be a delayed diagnosis of KD. IVIG therapy was effective, especially in cases of timely diagnosis. It is necessary to increase awareness of KD among clinicians and ultrasound diagnosticians