Mechanism for the formation of the high-altitude stagnant cusp: Cluster and SuperDARN observations

On 16 March 2002, Cluster moved from nightside to dayside, across the high-altitude northern cusp during an extended period of relatively steady positive IMF BY and BZ. Combined Cluster and SuperDARN data imply the existence of two reconnection sites: in the high- latitude northern hemisphere dusk and southern hemisphere dawn sectors. Within the cusp, Cluster encounters 3 distinct plasma regions. First, injections of magnetosheath-like plasma associated with dawnward and sunward convection suggest Cluster crosses newly- reconnected field lines related to the dusk reconnection site. Second, Cluster observes a Stagnant Exterior Cusp (SEC), characterized by nearly isotropic and stagnant plasma. Finally, Cluster crosses a region with significant antifield-aligned flows. We suggest the observed SEC may be located on newly re-closed field lines, reconnected first poleward of the northern hemisphere cusp and later reconnected again poleward of the southern hemisphere cusp. We discuss how the Cluster observations correspond to expectations of ’double reconnection’ model

Распространенность врожденного буллезного эпидермолиза у населения Российской Федерации

Goal. To study the prevalence of hereditary epidermolysis bullosa (HEB) in the Russian Federation. Materials and methods. The data on the number of HEB patients by subjects of the Russian Federation as well as their age and disease type were obtained based on questionnaires. The questionnaires were sent to dermatovenerology healthcare institutions from 85 subjects of the Russian Federation. The HEB prevalence rates in the subjects of the Russian Federation were calculated as the ratio of the number of HEB patients in the subject of the Russian Federation to the population size in the subject per million residents. Results. Information about 438 HEB patients (210 female and 228 male) aged 0-66 was collected in 70 subjects of the Russian Federation as of January 1, 2015. The disease type was specified for 139 patients (86 patients with common HEB, 50 patients with dystrophic HEB and 3 patients with the borderline form of HEB). No details about the disease type were provided for 299 patients (68.26%). The HEB prevalence rate in the subjects of the Russian Federation varies from 0 to 19.73 cases per million residents. Conclusion. These data on the HEB prevalence rate in 70 subjects of the Russian Federation are comparable to the data specified in literature sources providing information on the HEB prevalence rate in some foreign states. The data represent the first step to the development of clinical recommendations concerning HEB management and establishment of a register of in the Russian Federation.Цель. Изучить распространенность врожденного буллезного эпидермолиза (ВБЭ) среди населения Российской Федерации. Материал и методы. Сведения о числе больных ВБЭ в субъектах Российской Федерации, их возрасте и типе заболевания были получены посредством анкетирования. Анкеты были направлены в медицинские организации дерматовенерологического профиля 85 субъектов Российской Федерации. Показатели распространенности ВБЭ в субъектах Российской Федерации были рассчитаны как отношение числа больных ВБЭ в субъекте Российской Федерации к численности населения этого субъекта, в пересчете на миллион населения. Результаты. Из 70 субъектов Российской Федерации получены сведения о наличии 438 больных ВБЭ (210 женщин и 228 мужчин) в возрасте от 0 до 66 лет (по состоянию на 1 января 2015 г.). Тип заболевания в диагнозе был указан у 139 больных (простой ВБЭ - у 86 больных, дистрофический - у 50, пограничный - у 3). У 299 (68,26%) больных данных о типе заболевания представлено не было. Распространенность ВБЭ в субъектах Российской Федерации варьирует от 0 до 19,73 на 1 000 000 населения. Заключение. Полученные сведения о распространенности ВБЭ в 70 субъектах Российской Федерации сопоставимы с данными литературы, указывающими на распространенность ВБЭ в некоторых зарубежных странах. Полученные данные являются первым шагом к разработке клинических рекомендаций по ведению больных ВБЭ и созданию регистра больных ВБЭ в Российской Федерации

Development and validation of atazanavir and ritonavir determination in human plasma by HPLC-MS method

Introduction. HIV infection is one of the most relevant diseases from a medical, epidemiological and social point of view. Timely diagnosis, detection and control of the disease, adequate prescription of antiretroviral therapy can sufficiently reduce the viral load on the patient's body, reduce the risk of transmission of infection. Currently, combinations of various antiretroviral drugs are increasingly being prescribed as therapy. One of the most important is combination of atazanavir and ritonavir. The most important stage for the study of pharmacokinetics, studies of comparative pharmacokinetics and bioequivalence is the development of an analytical method that allows you to determine the investigated substances in human plasma. There are currently no published methods for the determination of atazanavir and ritonavir in human plasma using high performance liquid chromatography with mass selective detection using a single quadrupole mass detector. In this article presents the development and validation of a method for the determination of atazanavir and ritonavir in blood plasma after sample preparation by the method of protein precipitation. Aim. The aim of the study is to develop a method for the quantitative determination of atazanavir and ritonavir in human plasma by HPLC with mass spectrometric detection for performing the analytical part of pharmacokinetic studies. Materials and methods. Determination of atazanavir and ritonavir in human plasma by HPLC with mass spectrometric detection. A sample was prepared using protein deposition. Results and discussion. The method was validated of selectivity, matrix effect, calibration curve, accuracy, precision, limit of quantification, carry-over effect and sample stability. Conclusion. The method of the determination of atazanavir and ritonavir in human plasma was developed and validated by HPLC-MS. The analytical range of the was 50.0–10000.0 ng/mL in plasma for atazanavir and 10.0–2500.0 ng/mL in plasma for ritonavir. Method could be applied to determination of atazanavir and ritonavir in plasma for PK and BE studies. © Komarov T. N., Shohin I. E., Miskiv O. A., Bogdanova D. S., Aleshina A. V., Medvedev Yu. V., Bagaeva N. S., 2020

Statistical study of the electron-only mid-altitude cleft region: Cluster observations

The Cluster spacecraft have now amassed 3 years of data from crossings of the mid-altitude cleft/cusp.Comparison of particle data from the PEACE and CIS instruments shows that there is pronounceable difference in latitude between the equatorward edges of the electron and ion populations of the cleft region, and this difference increases in the dawn/dusk directions. We define the electron edge of the cleft by the first injection of the magnetosheath-like electrons and the disappearance of the trapped plasma-sheet particles.Correspondingly the ion boundary is identified by the first injection of magnetosheath-like ions. The region between these two boundaries, which we define as the 'electron-only' cleft region, contains parallel and/or antiparallel electron beams. This region is co-located with sharp enhancements of the wave activity and with transverse heating and outflow of ionospheric ions. We present a statistical study of the plasma properties of the electron-only region, including an estimation of the electron anisotropy, density and velocity. We estimate the latitudinal size of this region as a function of magnetic local time (MLT) and the interplanetary magnetic field (IMF) conditions. Moreover, using time differences between the first injection of the electrons and ions in the mid-altitude cusp, we infer a distance along the field lines to the reconnection site on the magnetopause

Correlation between suprathermal electron bursts, broadband extremely low frequency waves, and local ion heating in the midaltitude cleft//low-latitude boundary layer observed by Cluster

The Cluster spacecraft often cross the midaltitude cleft/cusp and observe a very well defined “electron-only cleft” region consisting of electron injections without magnetosheath ions. This region contains soft suprathermal (<500 eV) electron bursts in antifield and/or field-aligned directions. We present an example of such observations which shows that the O+ ion outflow at midaltitudes appears just poleward of the open-closed boundary simultaneously with electron injections and was observed in the cleft, cusp, and mantle in the form of narrow energy beam. Inside the “electron-only” cleft the suprathermal electron bursts are strongly correlated with strong O+ and H+ ion heating and with localized extra low frequency (ELF) (1–10 Hz) magnetic field wave power with broadband spectra. Our study shows that strong ion heating was observed only in the region with electron field-aligned anisotropy more than 2. In addition, comparison of particle data from two spacecraft, which crossed the heating region with a time difference of 4 min, shows the correlation between ion outflow fluxes and fluxes of the injected electrons. Whereas ELF electromagnetic waves are localized inside the ion heating region, ELF electrostatic waves are detected throughout the cleft/cusp/mantle regions, where strong ion heating was not observed, suggesting that electromagnetic ELF waves heat ions in the cleft region. Owing to the absence of magnetosheath ions and strong field-aligned currents, we suppose that inside “electron-only” cleft region the suprathermal electron bursts are most likely an energy source for the wave destabilization. We suggest that the location of the heating region and the level of the outflow ion fluxes could be related to electron injection in the cleft in such events

Comparative Cluster/Double Star observations of the high and low latitude dayside magnetopause

The launch of the Double Star mission has provided the opportunity to monitor events at distinct locations on the dayside magnetopause, in coordination with the quartet of Cluster spacecraft. We present results of two such coordinated studies. In the first, 6 April 2004, both Cluster and the Double Star TC-1 spacecraft were on outbound transits through the dawn-side magnetosphere. Cluster observed northward moving FTEs with +/- polarity, whereas TC-1 saw -/+ polarity FTEs. The strength, motion and occurrence of the FTE signatures changes somewhat according to changes in IMF clock angle. These observations are consistent with ongoing reconnection on the dayside magnetopause, resulting in a series of flux transfer events (FTEs) seen both at Cluster and TC-1. The observed polarity and motion of each FTE signature advocates the existence of an active reconnection region consistently located between the positions of Cluster and TC-1, lying north and south of the reconnection line, respectively. This scenario is supported by the application of a model, designed to track flux tube motion, to conditions appropriate for the prevailing interplanetary conditions. The results from the model confirm the observational evidence that the low-latitude FTE dynamics is sensitive to changes in convected upstream conditions. In particular, changing the interplanetary magnetic field (IMF) clock angle in the model predicts that TC-1 should miss the resulting FTEs more often than Cluster, as is observed. For the second conjunction, on the 4 Jan 2005, the Cluster and TC-1 spacecraft all exited the dusk-side magnetosphere almost simultaneously, with TC-1 lying almost equatorial and Cluster at northern latitudes at about 4 RE from TC-1. The spacecraft traverse the magnetopause during a strong reversal in the IMF from northward to southward and a number of magnetosheath FTE signatures are subsequently observed. One coordinated FTE, studied in detail by Pu et al, [this issue], carries and inflowing energetic electron population and shows a motion and orientation which is similar at all spacecraft and consistent with the predictions of the model for the flux tube dynamics, given a near sub-solar reconnection line. This event can be interpreted either as the passage of two parallel flux tubes arising from adjacent x-line positions, or as a crossing of a single flux tube at different positions

Exploring solar-terrestrial interactions via multiple imaging observers

How does solar wind energy flow through the Earth’s magnetosphere, how is it converted and distributed? is the question we want to address. We need to understand how geomagnetic storms and substorms start and grow, not just as a matter of scientific curiosity, but to address a clear and pressing practical problem: space weather, which can influence the performance and reliability of our technological systems, in space and on the ground, and can endanger human life and health. Much knowledge has already been acquired over the past decades, particularly by making use of multiple spacecraft measuring conditions in situ, but the infant stage of space weather forecasting demonstrates that we still have a vast amount of learning to do. A novel global approach is now being taken by a number of space imaging missions which are under development and the first tantalising results of their exploration will be available in the next decade. In this White Paper, submitted to ESA in response to the Voyage 2050 Call, we propose the next step in the quest for a complete understanding of how the Sun controls the Earth’s plasma environment: a tomographic imaging approach comprising two spacecraft in highly inclined polar orbits, enabling global imaging of magnetopause and cusps in soft X-rays, of auroral regions in FUV, of plasmasphere and ring current in EUV and ENA (Energetic Neutral Atoms), alongside in situ measurements. Such a mission, encompassing the variety of physical processes determining the conditions of geospace, will be crucial on the way to achieving scientific closure on the question of solar-terrestrial interactions.</p