Plasma volume and biochemical changes in athletes during bed rest chronic hyperhydration

Daily fluid and salt supplements (FSS) may be used to reduce plasma biochemical changes during bed rest (BR). The aim of this study was to evaluate the effect of a daily intake of FSS on plasma volume (PV) and biochemical changes during BR. Studies were done during a pre BR period of 15 days and during a BR period of 30 days. Thirty male athletes aged 22-26 years were chosen as subjects. They were divided into three groups: unsupplemented ambulatory control subjects (UACS), unsupplemented bed rested subjects (UBRS) and supplemented bed rested subjects (SBRS). The UBRS and SBRS were kept under a rigorous bed rest regime for 30 days. The SBRS took 26 ml water/kg body weight and 0.1 g sodium chloride/kg body weight daily. PV, protein, albumin, sodium (Na), Chloride (Cl), potassium (K), osmolality, creatinine, glucose, and whole blood haematocrit (Hct) and haemoglobin (Hb) concentrations were measured. PV increased significantly (P < or = 0.01) while plasma protein, albumin. Na, Cl, K, glucose, creatinine, osmolality, and whole blood Hb and Hct concentration decreased significantly (P < or = 0.01) in the SBRS group when compared with the UBRS group. By contrast, PV decreased significantly (P < or = 0.01), while plasma protein, albumin, Na, Cl, K, glucose, creatinine, osmolality and whole blood Hct and Hb concentration increased significantly (P < or = 0.01) in the UBRS group when compared with the SBRS and UACS groups. The measured parameters did not change significantly in the UACS group when compared with the baseline control values. It was concluded that a daily intake of FSS may be used to attenuate PV losses and biochemical changes in endurance trained athletes during bed rest.     

Electric propulsion plasma plume interaction with “Phobos-Soil” spacecraft structural components

Assessment was made by calculations for the possible consequences of the effect of plasma plume injected by the solar electric propulsion system (SEPS) on the structural components of “Phobos-Soil” spacecraft (SC). Propulsion system comprises three SPT-140 thrusters, two of which should secure the required total thrust impulse during 8000 hours of operation approximately. Variation of the solar panel (SP) properties as a result of their surface contamination with the products of erosion of thruster and SC structural components is the primary negative consequence of plasma plume effect on the SC. Calculation study for the processes of erosion, particle flow distribution, and contaminating coating formation on the SP surface was made for different SEPS arrangements. It is shown that power reduction for the landing module SP sections, which are subjected to the contaminating coating deposition to the most extent, will not exceed 5% of the nominal level.     

Kinetic-Hydrodynamic Models of the Solar Wind Interaction with the Partially Ionized Supersonic Flow of the Local Interstellar Gas: Predictions and Interpretations of the Experimental Data

At present there is no doubt that the local interstellar medium (LISM) is mainly partially ionized hydrogen gas moving with a supersonic flow relative to the solar system. The bulk velocity of this flow is approximately equal ～26 km/s. Although the interaction of the solar wind with the charged component (below plasma component) of the LISM can be described in the framework of hydrodynamic approach, the interaction of H atoms with the plasma component can be correctly described only in the framework of kinetic theory because the mean free path of H atoms in the main process of the resonance charge exchange is comparable with a characteristic length of the problem considered. Results of self-consistent, kinetic-hydrodynamic models are considered in this review paper. First, such the model was constructed by Baranov and Malama (J. Geophys. Res. 98(A9):15,157–15,163, 1993). Up to now it is mainly developed by Moscow group taking into account new experimental data obtained onboard spacecraft studying outer regions of the solar system (Voyager 1 and 2, Pioneer 10 and 11, Hubble Space Telescope, Ulysses, SOHO and so on). Predictions and interpretations of experimental data obtained on the basis of these models are presented. Kinetic models for describing H atom motion were later suggested by Fahr et al. (Astron. Astrophys 298:587–600, 1995) and Lipatov et al. (J. Geophys. Res. 103(A9):20,631–20,642, 1998). However they were not self-consistent and did not incorporate sources to the plasma component. A self-consistent kinetic-hydrodynamic model suggested by Heerikhuisen et al. (J. Geophys. Res. 111:A06110, 2006, Astrophys. J. 655:L53–L56, 2007) was not tested on the results by Baranov and Malama (J. Geophys. Res. 111:A06110, 1993) although it was suggested much later. Besides authors did not describe in details their Monte Carlo method for a solution of the H atom Boltzmann equation and did not inform about an accuracy of this method. Therefore the results of Heerikhuisen et al. (J. Geophys. Res. 111:A06110, 2006) are in open to question and will not be considered in this review paper. That is why below we will mainly consider a progress of the Moscow group on heliospheric modelling endeavours in the kinetic-hydrodynamic approach. Criticism of the models that treat interstellar hydrogen in the heliosphere as several fluids is given. It is shown that the multi-fluid models give rise to unreal results especially for distributions of neutral component parameters. Magnetohydrodynamic (MHD) modelling of the solar wind interaction with the LISM gas is also reviewed.     

Fluid and salt supplementation effect on body hydration and electrolyte homeostasis during bed rest and ambulation

Bed rest (BR) induces significant urinary and blood electrolyte changes, but little is known about the effect of fluid and salt supplements (FSS) on catabolism, hydration and electrolytes. The aim was to measure the effect of FSS on catabolism, body hydration and electrolytes during BR.

Studies were done during 7 days of a pre-bed rest period and during 30 days of a rigorous bed rest period. Thirty male athletes aged, 24.6±7.6 years were chosen as subjects. They were divided into three groups: unsupplemented ambulatory control subjects (UACS), unsupplemented bed rested subjects (UBRS) and supplemented bed rested subjects (SBRS). The UBRS and SBRS groups were kept under a rigorous bed rest regime for 30 days. The SBRS daily took 30 ml water per kg body weight and 0.1 sodium chloride per kg body weight.

Plasma sodium (Na), potassium (K), calcium (Ca) and magnesium (Mg) levels, urinary Na, K, Ca and Mg excretion, plasma osmolality, plasma protein level, whole blood hemoglobin (Hb) and hematocrit (Hct) level increased significantly (p≤0.05), while plasma volume (PV), body weight, body fat, peak oxygen uptake, food and fluid intake decreased significantly (p≤0.05) in the UBRS group when compared with the SBRS and UACS groups. In contrast, plasma and urinary electrolytes, osmolality, protein level, whole blood Hct and Hb level decreased significantly (p≤0.05), while PV, fluid intake, body weight and peak oxygen uptake increased significantly (p≤0.05) in the SBRS group when compared with the UBRS group. The measured parameters did not change significantly in the UACS group when compared with their baseline control values.

The data indicate that FSS stabilizes electrolytes and body hydration during BR, while BR alone induces significant changes in electrolytes and body hydration. We conclude that FSS may be used to prevent catabolism and normalize body hydration status and electrolyte values during BR.     

Spacecraft dynamics with regard to elastic gravitational stabilizer deployment

The present paper deals with the study the dynamics of the spacecraft with gyro-gravitational system of stabilization. The deployment of the boom of the gravitational stabilizer commences after placing the spacecraft into the orbit and completion of the preliminary damping, when the gyroscopes are uncaged. Primarily the boom is the pre-stressed tape wound on the special drum. When the drum starts deploying the tape, it turns into the elastic cylindrical rod with the mass at its tip. The objective of the study is the creation of the generalized mathematical model and the conducting of the computer modelling of the spacecraft dynamics. The equations of motion are worked out with the use of the Lagrangian formalism. The numerical simulation of typical modes of system functioning is conducted. It is shown that the folding and the following deployment of the boom result in the turn of the spacecraft by 180° about the axis of the pitch. The results illustrate the behaviour of the main system variables.     

Diurnal and longitudinal variations in the earth’s ionosphere in the period of solstice in conditions of a deep minimum of solar activity

The results of studies of longitudinal and LT variations in parameters of the ionosphere–plasmasphere system, obtained using the Global Self-Consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP), assimilation ionospheric model IRI Real-Time Assimilation Mapping (IRTAM), and satellite and ground-based observational data are presented in the paper. The study of the main morphological features of longitudinal and LT variations in the critical frequency of the ionospheric F2 layer (foF2) and total electron content (TEC) depending on latitude in the winter solstice during a solar-activity minimum (December 22, 2009) is carried out. It is shown that the variations in foF2 and TEC, on the whole, are identical, and so mutually substitutable, while creating empirical models of these parameters in quiet geomagnetic conditions. The longitudinal and LT variations in both foF2 and TEC are within an order of magnitude everywhere except for the equator anomaly region, where LT variation is larger by an order of magnitude than longitudinal variation. According to the results of the study, in the American longitudinal sector at all latitudes of the Southern (summer) Hemisphere, maxima of foF2 and TEC are formed. The near-equatorial and high-latitudinal maxima are separated out from these. The estimate of the contribution into the longitudinal variation in foF2 and TEC for various local time sectors and at various latitudes has been obtained for the first time. In the Southern (summer) Hemisphere, longitudinal variation in foF2 and TEC is formed in the nighttime.     

边界层转捩过程三维扰动的发展和演化

引入展向调制的二维人工扰动激发平板边界层转捩,利用水槽氢气泡流动显示技术观察到转捩边界层中典型三维扰动的产生和发展,包括Λ结构、发卡涡以及发卡涡演化生成环状涡的过程.实验结果显示出环状涡和尖峰结构的关系,直接证实了尖峰结构的产生机理.在流动紊乱化初始阶段发现常出现在湍流边界层中的暗斑结构,结果表明与暗斑相伴随的局部高剪切层不稳定可能是流动紊乱化的重要原因.     

Formation mechanism of great positive TEC disturbances prior to Wenchuan earthquake on May 12, 2008

The problems of physical explanation and possible mechanisms of the seismo-ionospheric effects formation are under discussion now. There are proposed different mechanisms of such effects, for example, large- and small-scale internal gravity waves (IGWs), atmospheric electric field, electromagnetic fields and emissions. However, the appearance of local large-scale seismo-ionospheric anomalies in Total Electron Content (TEC) is possible to explain only by two mechanisms: an atmospheric electric field and/or small-scale IGWs. In this paper, the simulation results for reproduction of the observed seismo-ionospheric great positive effects in TEC prior to strong Wenchuan earthquake are presented. The obtained results confirm the proposed mechanism of seismo-ionospheric effects formation by the penetration of the seismogenic electric field from the atmosphere into the ionosphere. It is suggested that so great TEC enhancement observed 3 days prior to Wenchuan earthquake could be explained by combined action of seismogenic vertical electric field and IGWs generated by the solar terminator.     

On Possible Causes of Positive Disturbance of Global Electronic Content during a Complex Heliogeophysical Event on September 2017

Cosmic Research - This paper presents the results of model calculations of the behavior of the ionosphere during a complex space-weather event that occurred in September 2017. The main attention is...     

Ionospheric response to solar and magnetospheric protons during January 15–22, 2005: EAGLE whole atmosphere model results

We present an analysis of the ionosphere and thermosphere response to Solar Proton Events (SPE) and magnetospheric proton precipitation in January 2005, which was carried out using the model of the entire atmosphere EAGLE. The ionization rates for the considered period were acquired from the AIMOS (Atmospheric Ionization Module Osnabrück) dataset. For numerical experiments, we applied only the proton-induced ionization rates of that period, while all the other model input parameters, including the electron precipitations, corresponded to the quiet conditions. In January 2005, two major solar proton events with different energy spectra and proton fluxes occurred on January 17 and January 20. Since two geomagnetic storms and several sub-storms took place during the considered period, not only solar protons but also less energetic magnetospheric protons contributed to the calculated ionization rates. Despite the relative transparency of the thermosphere for high-energy protons, an ionospheric response to the SPE and proton precipitation from the magnetotail was obtained in numerical experiments. In the ionospheric E layer, the maximum increase in the electron concentration is localized at high latitudes, and at heights of the ionospheric F2 layer, the positive perturbations were formed in the near-equatorial region. An analysis of the model-derived results showed that changes in the ionospheric F2 layer were caused by a change in the neutral composition of the thermosphere. We found that in the recovery phase after both solar proton events and the enhancement of magnetospheric proton precipitations associated with geomagnetic disturbances, the TEC and electron density in the F region and in topside ionosphere/plasmasphere increase at low- and mid-latitudes due to an enhancement of atomic oxygen concentration. Our results demonstrate an important role of magnetospheric protons in the formation of negative F-region ionospheric storms. According to our results, the topside ionosphere/plasmasphere and bottom-side ionosphere can react to solar and magnetospheric protons both with the same sign of disturbances or in different way. The same statement is true for TEC and foF2 disturbances. Different disturbances of foF2 and TEC at high and low latitudes can be explained by topside electron temperature disturbances.