ANALYSIS OF DUAL-FREQUENCY INTERFEROMETRY APPLICABILITY FOR TARGET ELEVATION ANGLE MEASUREMENT USING TWO-COORDINATE RADARS

Subject and Purpose. The study deals with the dual-frequency radio interferometry technique, which is based on the employment of two fairly close frequencies with the aim to remove ambiguity of the radar target elevation estimation using 2D-radar and eliminate 2 pm-uncertainty of the signal phase difference measurement. Analysis of random noise action on the accuracy of the elevation angle estimation by the dual-frequency radio interferometry and assessment of practical applicability of the method make up the purpose of the paper. Methods and Methodology. The noise action on the elevation angle measurement accuracy is examined through a series of analytical calculations with the use of statistical analysis methods. The noise in each receiving channel is modeled in terms of additive, statistically independent stationary Gaussian processes with zero mean values and equal variances. The calculation results are checked via computer simulations with statistics estimations for 106 random noise realizations. Results. A correct condition has been developed for the sector width where the target elevation angle is unambiguously estimated depending on the space separation of the antennas (baselines) and the frequency ratio. Expressions for elevation angle estimation errors have been obtained, showing that the error is mainly contributed by the faults in the determination of the ambiguity interval number. A probability of the correct determination of the ambiguity interval number has been derived depending on the signal- to-noise ratio and the frequency difference, indicating that almost one hundred per cent probability of the correct determination of the ambiguity interval number is only achieved when the signal-to-noise ratio exceeds 30 dB. A comparative analysis has been performed between the methods of dual-frequency interferometry and conventional phase-difference direction finding in the case of close X-band frequencies and the same sectors of survey. Conclusions. The dual-frequency radio interferometry technique with close frequencies has been shown to outperform the standard phase-difference direction-finding method only when the signal-to-noise ratio is sufficiently high (over 30 dB). In principle, the accuracy of the technique seems possible to improve by taking significantly different frequencies selected with regard to the scale negotiation condition. However, it should be mentioned that the implementation of the relevant algorithm in practice is much more complicated than the conventional scheme with a single frequency and several antenna baselines

Data-sharing as a quid pro quo of co-regulation in the EU

The paper focuses on the defining of the co-regulation of national and supranational legal regimes’ features of data-sharing in the digital platforms’ functioning on the example of the EU’s practice with a special attention to the disintegration process of Brexit. Data-sharing is one of the most appropriate spheres to demonstrate specific traits of digital platforms — the cross-border character of their operation. This demands quid pro quo interaction of the national and supranational regulatory regimes, filling the gap associated with the lack of international regulation and the inability to harmonize law. We begin with the theoretical characterization of information and personal data, the right to privacy, and classifications of interventions in private life. The EU has been chosen as an example, acting as a flagship of interaction of national and supranational legal orders in relation to the co-regulation of cross-border data-sharing in digital platforms. Interaction of the EU on the principle of quid pro quo, based on the practice of making decisions on adequacy, is considered in the context of Brexit and the relevant law-making practice of the UK. The discussion is complemented by examples of similar EU relations with South Korea and the United States. Based on the analysis, the authors conclude that the EU supranational legal order has a high degree of influence on the national legislation of third countries, which contributes to the constant development of regulation in the sphere and the strengthening of international integration

Estimation of disease activity in patients with ankylosing spondylitis in the real practice of a rheumatologist in Russia (Part 2)

Objective: to compare different methods for estimating ankylosing spondylitis (AS) activity in the real practice of a rheumatologist in the Russian Federation. Subjects and methods. The investigation enrolled 464 patients with AS, who had consecutively visited rheumatologists for 4 months in 24 cities and towns of Russia. A specially designed clinical card was filled out for all patients. BASDAI and ASDAS scores were estimated by a physician and erythrocyte sedimentation rate (ESD) and C-reactive protein (CRP) were measured in all the patients. Mini-BASDAI scores were determined in patients with axial AS. The diagnosis of the disease was verified at the Research Institute of Rheumatology, Russian Academy of Medical Sciences, according to the 1984 modified New York criteria, by including X-ray film estimation. All activity assessment methods were compared. Results. The valid diagnosis of AS was confirmed in 330 (71.1%) out of all 464 patients included into the study; axial AS was present in 178 of them; their mean age was 39.7+10.2 years; the mean duration of disease was 14.6+2.6 years; 86% were men and 14% were women. About 61 and 74% of the patients (n = 178) had high BASDAI and mini-BASDAI scores, respectively; 88% had high and very high ASDAI (ESR) scores; the mean ESR (Westergren method) was 33.8+29 mm/h and CRP (n = 249) was 30 mg/l. Conclusion. On assessing the activity of disease, rheumatologists are primarily oriented to total activity scores and blood acutephase indicators (ESR and CRP) in real clinical practice. Patients with high disease activity calculated from BASDAI and ASDAS scores proved to be more. In its turn, ASDAS more frequently reveals high AS activity than BASDAI

Труднолечимый ревматоидный артрит. Какой он?

The widespread introduction into clinical practice of modern approaches to the treatment of rheumatoid arthritis (RA), the rational use of traditional and targeted antirheumatic drugs can effectively suppress inflammatory activity, restrain the progression of the disease and improve the quality of life of patients. At the same time, in some patients, even after the repeated change of targeted drugs, it is not possible to achieve the target level of RA activity. Serious difficulties arising in the management of such patients raised the question of identifying a special variant of the disease – difficult-to-treat (D2T) RA. The presence of various variants of D2T RA and the need to use a personalized approach to therapy justify the creation of special recommendations for the management of this category of patients. The first step in preparing these recommendations was the definition of D2T RA recently presented by the EULAR working group. It includes three criteria: 1) insufficient effectiveness of the therapy; 2) the presence of an active symptomatic disease; 3) clinical perception.Широкое внедрение в клиническую практику современных подходов к лечению ревматоидного артрита (РА), рациональное использование традиционных и таргетных противоревматических препаратов позволяют эффективно подавлять воспалительную активность, сдерживать прогрессирование болезни и улучшать качество жизни больных. Вместе с тем у части пациентов даже после повторной смены таргетных препаратов не удается добиться целевого уровня активности РА. Серьезные затруднения, возникающие при ведении таких пациентов, поставили вопрос о выделении особого варианта болезни – труднолечимого (difficult to treat, D2T) РА. Наличие разнообразных вариантов D2T РА и необходимость использования персонифицированного подхода к терапии обосновывают создание специальных рекомендаций по ведению данной категории больных. Первым шагом к подготовке данных рекомендаций стало определение понятия D2T РА, недавно представленное рабочей группой EULAR. Оно предусматривает соответствие пациента трем критериям: 1) недостаточная эффективность проводимой терапии; 2) наличие активного симптоматического заболевания; 3) клиническое восприятие

Ранний артрит как ревматологический хамелеон: описание клинического случая

The article discusses the difficulties of differential diagnosis of early arthritis and inflammatory bowel diseases with a predominant clinical picture of extraintestinal manifestations, in particular, articular syndrome. The clinical observation demonstrates features of the course of such conditions, a long diagnostic search and a wide list of diseases included in differential diagnostics range.В статье рассматриваются сложности дифференциальной диагностики раннего артрита и воспалительных заболеваний кишечника с преобладающей клинической картиной внекишечных проявлений, в частности суставного синдрома. Представлено клиническое наблюдение, демонстрирующее особенности течения таких состояний, длительный диагностический поиск и широкий перечень заболеваний, включенных в круг дифференциальной диагностики

Труднолечимый ревматоидный артрит (difficult-to-treat RA) в клинической практике ревматологического стационара. Первый взгляд

Objective: to compare the course of the disease and therapy in rheumatoid arthritis (RA) patients who meet and do not meet the criteria for difficult- to-treat RA (D2T).Patients and methods. The study included RA patients who met the 2010 ACR/EULAR criteria and who were hospitalized in the V.A. Nasonova Research Institute of Rheumatology from March to October 2021. All patients underwent a conventional clinical and laboratory examination, radiography of the hands and distal feet, and the radiological stage of RA according to Steinbroker was assessed. To determine the inflammatory activity, the DAS28-ESR and DAS28-CRP indices were calculated.Results and discussion. The study included 303 patients with RA, 25 (8.4%) of them had D2T RA. The duration of RA in the D2T group was significantly longer than in other patients (15.9±11.8 and 11.9±9 years, respectively; p=0.04). X-ray changes in the joints in D2T were more pronounced. Patients with D2T had higher inflammatory activity at the time of hospitalization than patients who had continued prior therapy with biologic/targeted synthetic DMARDs. The dose of glucocorticoids (GC) in patients with D2T RA was higher compared to patients of other groups: on average 8.3±5.1 and 6.4±2.9 mg/day, respectively (p=0.02).Conclusion. The results of this study suggest that in Russia, as well as abroad, the treat-to-target principle has not yet become widespread, and the selection of adequate therapy takes too much time. At the same time, Russian rheumatologists primarily use GC to suppress inflammatory activity. The introduction of modern recommendations for the management of patients with RA into routine clinical practice, could possibly restrain the formation of D2T RA.Цель исследования – сравнительное изучение особенностей течения и терапии ревматоидного артрита (РА) у больных, соответствующих и не соответствующих критериям труднолечимого РА (difficult-to-treat RA, D2T).Пациенты и методы. В исследование включены больные РА, удовлетворявшие критериям ACR/EULAR 2010 г. и госпитализированные в ФГБНУ «Научно исследовательский институт ревматологии им. В.А. Насоновой» с марта по октябрь 2021 г. Всем пациентам проводились общепринятое клинико-лабораторное обследование, рентгенография кистей и дистальных отделов стоп, оценивалась рентгенологическая стадия РА по Штейнброкеру. Для определения воспалительной активности вычислялись индексы DAS28-СОЭ и DAS28-СРБ.Результаты и обсуждение. В исследование вошли 303 больных РА, у 25 (8,4%) из которых выявлен D2T. Длительность РА в группе D2T была значимо больше, чем у остальных пациентов: соответственно 15,9±11,8 и 11,9±9 лет (р=0,04). Рентгенологические изменения суставов при D2T были более выраженными. На момент госпитализации у пациентов с D2T отмечалась более высокая воспалительная активность, чем у больных, которым была продолжена предшествующая терапия генно-инженерными биологическими препаратами / таргетными синтетическими базисными противовоспалительными препаратами. Доза глюкокортикоидов (ГК) у пациентов с D2T была выше по сравнению с пациентами других групп: в среднем 8,3±5,1 и 6,4±2,9 мг/сут соответственно (р=0,02).Заключение. Результаты исследования позволяют предположить, что в России, как и за рубежом, принцип лечения до достижения цели пока не получил широкого распространения, а подбор адекватной терапии занимает слишком много времени. При этом для подавления воспалительной активности российские ревматологи используют в первую очередь ГК. Внедрение в рутинную клиническую практику современных рекомендаций по ведению больных РА, по-видимому, могло бы сдерживать формирование D2T

The MHD nature of ionospheric wave packets excited by the solar terminator

We obtained the first experimental evidence for the magnetohydrodynamic (MHD) nature of ionospheric medium-scale travelling wave packets (MSTWP). We used data on total electron content (TEC) measurements obtained at the dense Japanese network GPS/GEONET (1220 stations) in 2008-2009. We found that the diurnal, seasonal and spectral MSTWP characteristics are specified by the solar terminator (ST) dynamics. MSTWPs are the chains of narrow-band TEC oscillations with single packet's duration of about 1-2 hours and oscillation periods of 10-20 minutes. Their total duration is about 4--6 hours. The MSTWP spatial structure is characterized by a high degree of anisotropy and coherence at the distance of more than 10 wavelengths. The MSTWP direction of travelling is characterized by a high directivity regardless of seasons. Occurrence rate of daytime MSTWPs is high in winter and during equinoxes. Occurrence rate of nighttime MSTIDs has its peak in summer. These features are consistent with previous MS travelling ionosphere disturbance (TID) statistics obtained from 630-nm airglow imaging observations in Japan. In winter, MSTWPs in the northern hemisphere are observed 3-4 hours after the morning ST passage. In summer, MSTWPs are detected 1.5-2 hours before the evening ST occurrence at the point of observations, at the moment of the evening ST passage in the magneto-conjugate point. Both the high Q-factor of oscillatory system and synchronization of MSTWP occurrence with the solar terminator passage at the point of observations and in the magneto-conjugate area testify the MHD nature of ST-excited MSTWP generation. The obtained results are the first experimental evidence for the hypothesis of the ST-generated ion sound waves.Comment: 12 pages, 3 figure