УМСТВЕННАЯ РАБОТОСПОСОБНОСТЬ И ФУНКЦИОНАЛЬНОЕ СОСТОЯНИЕ ГОЛОВНОГО МОЗГА У СТУДЕНТОК МЛАДШИХ КУРСОВ ПРИ РАЗНЫХ УРОВНЯХ СОЛНЕЧНОЙ АКТИВНОСТИ

Propagation of stationary planetary waves to the thermosphere at different levels of solar activity

\n Aims. The study aims to find a relationship between the rotation of the small bright coronal structures (SBCS) described by the solar rotation parameters and indices of solar activity on monthly and yearly temporal scales.\n Methods. We analyse precise measurements of the solar differential rotation determined by tracing SBCS in SOHO-EIT images and compare the derived solar rotation parameters with the status of solar activity in the period 1998 − 2006. Full-disc solar images obtained with the Extreme ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory (SOHO) were used to analyse solar differential rotation determined by tracing SBCS. An automatic method to identify and track the SBCS in EIT full-disc images with a six hour cadence is applied. We performed a statistical analysis of the monthly and yearly values of solar sidereal rotation velocity parameters A and B (corresponding to the equatorial rotation velocity and the gradient of the solar differential rotation, respectively) as a function of various solar activity indices.\n Results. The dependence of the solar rotation on the phase of the solar cycle was found. It is clearly visible for the solar rotation parameter A, whilst the results are not conclusive for parameter B. The relationship between the solar rotation and activity, expressed by the monthly relative sunspot number, the smoothed monthly relative sunspot number, the yearly relative sunspot number, and the interdiurnal variability (IDV) index was investigated. The statistically significant correlation was found for the solar rotation parameter A, whilst a very low and insignificant correlation was obtained for the rotation parameter B. \n Conclusions. During the maximum of the solar cycle 23 and just after it, the equatorial solar rotation velocity was lower than in other phases of the cycle, when there was less activity. This is consistent with other observational findings, obtained by different tracers and methods.\n

Variations in the total solar irradiance (TSI) associated with solar activity have been argued to influence the Earth's climate system, in particular when solar activity deviates from the average for a substantial period. One such example is the 17th Century Maunder Minimum during which sunspot numbers were extremely low, as Earth experienced the Little Ice Age. Estimation of the TSI during that period has relied on extrapolations of correlations with sunspot numbers or even more indirectly with modulations of galactic cosmic rays. We argue that there is a minimum state of solar magnetic activity associated with a population of relatively small magnetic bipoles which persists even when sunspots are absent, and that consequently estimates of TSI for the Little Ice Age that are based on scalings with sunspot numbers are generally too low. The minimal solar activity, which measurements show to be frequently observable between active-region decay products regardless of the phase of the sunspot cycle, was approached globally after an unusually long lull in sunspot activity in 2008–2009. Therefore, the best estimate of magnetic activity, and presumably TSI, for the least-active Maunder Minimum phases appears to be provided by direct measurement in 2008–2009. The implied marginally significant decrease in TSI during the least active phases of the Maunder Minimum by 140 to 360 ppm relative to 1996 suggests that drivers other than TSI dominate Earth's long-term climate change.

We have investigated the solar activity dependence of the electron density at equatorial and low latitudes using 6 years (a) of measurements between 1 August 2000 and 1 August 2006 from CHAMP and compared it with the international reference ionosphere (IRI) model. The solar activity dependence observed by CHAMP at 400 km altitude exhibits significant variation with latitude, season, and local time. First, the electron density in the crest regions of the equatorial ionization anomaly (EIA) grows roughly linearly from solar minimum to solar maximum, with a higher growth rate than that in the EIA trough region. Second, the solar activity dependence in the EIA crest regions varies strongly with season. The growth rate of the electron density with increasing solar activity around equinoxes is about 1.5 to 2 times greater than that near solstices. Third, the solar activity dependence of the EIA structure varies significantly with local time. In the noon sector the crest‐to‐trough ratio (CTR) obtained at 400 km altitude varies within only a small range between 1.14 and 1.43 from solar minimum to solar maximum. In the postsunset local time sector, however, the CTR grows remarkably with solar activity level, reaching values of above 3.9 at solar maximum. These differences are attributed to the different solar activity dependence of the vertical plasma drift in corresponding local time sectors. The IRI model was found to reproduce the equatorial electron density well near 400 km in the noon sector at all solar activity levels. However, it significantly overestimates it in the postsunset to premidnight sector at high solar activity levels. The major cause for this overestimation has been found to be the IRI's inadequate representation of the F2 layer maximum height (hmF2) in this sector, while the IRI's lack of equatorial spread F seems to play only a minor role.

The solar activity by wavelet-based multifractal analysis

An attempt is made to estimate the plasmaspheric electron content (PTEC) using the data observed from the ISR (Incoherent Scatter Radar) and GPS at Millstone Hill (42. 6 degrees N, 288. 5 degrees E). We first present a brief description on the method we used in this study, then the variation of PTEC is studied. The electron density profile obtained by the ISR at Millstone Hill is fitted using Chapman function with varying scale heights, and then the ISR TEC is calculated as an integral of electron density from 100km to 1000km of the profile. The difference between GPS TEC (which is up to an altitude of 20200 km) and ISR TEC can be taken approximately as the plasmaspheric electron content (PTEC). Data from both high solar activity years (2000 and 2002) and low solar activity years (2005 and 2008) are used for the present study. The results we obtained indicate that both PTEC and the relative contribution of PTEC (to GPSTEC) exhibit obvious diurnal variation patterns, with PTEC being higher during daytime than during nighttime and the relative contribution of PTEC is higher during nighttime than during daytime. PTEC can vary from 4 to 14 TECU (1TECU = 10(16)el/m(2)) and the contribution of PTEC to GPS TEC reaches 60% during nighttime in the month of high solar activity level, while in the month of low solar activity, the value of PTEC is generally 3 similar to 7 TECU with the highest contribution about 80% at night. The variation pattern and trends in our results are in agreement with those obtained by other researches based on different measurements and techniques, and the magnitude is also agreed. This provides a support to the validity of our method. Unlike the ionosonde/digisonde which can only explore the bottomside ionosphere under the F2 peak, the ISR has the advantage to explore from a low to high altitude range and thus can provide both the bottomside and topside electron density profile. For this reason, the PTEC derived from ISR data (combined with GPS TEC) is more realistic than that from ionosonde data (combined with GPS TEC). This latter approach was often adopted by some former researchers.

The impact of asymmetrical distribution of solar activity on geomagnetic indices throughout five solar activity cycles

The starting times of mass spontaneous social movements have been compared with temporal changes in solar activity (Wolf numbers) and in the Aa index of geomagnetic activity. It is shown that relatively high values of solar and, hence, geomagnetic activity are typical (on average) of a set of years when social cataclysms began. In addition, the relationship between social activity and geomagnetic activity is expressed somewhat more strongly than with solar activity. Heliogeomagnetic activity itself is not, however, the cause of social conflicts, as is evidenced by the weakness of the statistical relationship and the fact that the time intervals of an extremely large number of social conflicts (the decades of the 1800s, 1910s, and 1990s) occur during periods of a reduced mean level of solar and geomagnetic activity. From an averaged statistical model of the solar-geomagnetic influence on social activity and the current status and forecast of the 24th solar cycle, we can assume that heliogeomagnetic factors will contribute to an increased level of sociopolitical activity at least until the end of 2014 and, possibly, a little longer.

The results of studies on the relationship between cosmophysical activity and animal productivity (the rhythm of milk yield of cows and the chemical composition of milk, the biochemical composition of raw milk) are presented. It was found that during the phase of growth of the activity of the Sun and the increase in the values of the Wolf index (sunspot) in the first half of the 24-year eleven-year cycle of solar activity, the average value of Wolf (sunspot) numbers varied from 0 to 100. For 2-3 years, at the lower peak of solar activity, and 2-3 years - at the top peak of activity, minimal and unreliable correlation relationships were observed. The most stable connections occur in the middle of an upswing or a decrease in solar activity. An increase in the relationship between the studied indicators was observed when the animals achieved maximum productivity. With an increase in milk yield from 7500 kg to 8500 kg, and further to 10,000 kg, the correlation coefficient was + 0.37, + 0.52 and + 0.64, respectively. The maximum influence of solar activity Wolf (sunspot) numbers) on the average productivity of one animal in the household is manifested at the peak of solar activity growth. It has been established that during the years of the rise of solar activity with low absolute values of Wolf (sunspot) numbers, low yields are more likely, and in high solar activity years, higher dairy values (record) are more likely. It was noted that all the components of milk decreased on days of increasing solar activity. The correlation coefficients for protein and milk fat content with Wolf (sunspot) numbers were r = -0.34 and r = -0.22, P 0.95. Correlation analysis revealed a reliable correlation of bacterial contamination and the number of somatic cells r = +0.28 and r = +0.31 (at P 0.95), respectively, with the Wolf (sunspot) numbers. In the collection milk, the negative correlation by fat content r = -0.12, density r = -0.18, acidity r = -0.17, protein content r = -0.19, sugar content r = -0.14, minerals r = -0.17 was observed with an increase in solar activity.

Relationship between sunspot number and seasonal rainfall over Kerala using wavelet analysis

The ionosphere Total Electron Content (TEC) measurement using Global Positioning System (GPS) technology (GPS-TEC) is carried out over the equatorial low latitudes of Indian region viz; Bangalore $\left(13.0^{0}\mathrm{~N}, 77.5^{0}\mathrm{E}\right)$, Hyderabad $\left(17.5^{0} \mathrm{~N}, 78.5^{0} \mathrm{E}\right)$, Bhopal $\left(23.0^{0} \mathrm{~N}, 77.2^{0} \mathrm{E}\right)$, Delhi $\left(28.7^{0} \mathrm{~N}, 77.2^{0} \mathrm{E}\right)$, Ahmedabad $\left(23.0^{0} \mathrm{~N}, 72.5^{0} \mathrm{E}\right)$ and Guwahati $\left(26.0^{0} \mathrm{~N}, 92.0^{0} \mathrm{E}\right)$ for low solar activity (LSA i.e., 2008) and high solar activity (HSA i.e., 2014) periods of solar cycle 24. The measured GPS-TEC were analysed to report diurnal, day to day and monthly variation with equatorial low latitude, solar activity and geomagnetic conditions. Moreover, GPS-TEC variation is investigated to find the correlation with Sun Spot Number (SSN), Solar Flux (F10.7 cm) and Ap-index. From the results, it is found that the TEC is enhanced during HSA (2014) compared to LSA. However, depletion is observed during pre-sunrise hours (4:00 hrs. to 6:00 hrs.) particularly in spring and autumn equinox periods of HSA (2014). Also, found that the equatorial ionization anomaly (EIA) crest which is occurred over Bhopal region during LSA (2008) is shifted to the higher latitudes (i.e. Delhi region) during HSA period (2014). Further, it is observed that Ap-index and F10.7 cm have the better correlation with GPS-TEC compared to SSN for both LSA (2008) and HSA (2014) periods. Additionally, it is also observed that the increased solar activity has negative impact on correlation between GPS-TEC and Ap-index and F10.7 cm.

Evidence of solar signals in tree rings of Smith fir from Sygera Mountain in southeast Tibet

Actually, solar constant is not constant but fluctuated by ±1.5% of their average value. Solar constant indicates that the value is not constant but varies with time. Such variation is correlated with solar activity and cosmic ray. Correlation analysis shows a strong correlation between solar activity and cosmic ray and between solar activity and solar constant. Solar activity indicates by sunspot number. Correlations between solar constant variations and sunspot number variations were found to be higher than ones between variations in cosmic ray and solar constant. It was also found a positive correlation between solar constant and sunspot number, with correlation coefficient about +0.77/month and +0.95/year. In other hand, negative correlation between solar constant and cosmic ray flux i.e. −0.50/month and −0.62/year were found for monthly and yearly data respectively. A similar result was also found for the relationship between solar activity and cosmic ray flux with a negative correlation, i.e. −0.61/month and −0.69/year. When solar activities decrease, the clouds cover rate increase due to secondary ions produced by cosmic rays. The increase in the cloud cover rate causes the decrease in solar constant value and solar radiation on the earth’s surface. Solar constant plays an important role in the planning and technical analysis of equipment utilizing solar energy.

Using the facilities at Heliophysics Science Division of NASA Goddard Space Flight Center, Greenbelt, MD, USA, we attempted to investigate the impact of solar magnetic activities on the climate of Wet Zone West Africa. The solar activity data namely, Sunspot Number (SSN) was obtained from the Royal Observatory of Belgium, Brussels; and Geomagnetic aa-index was obtained from World Data Center, Kyoto, Japan. Surface Air Temperature (SAT) and Rainfall data [for Port Harcourt in Nigeria and Abidjan in Cote D’Ivoire] were obtained from the HadCRUT-4 project of Climate Research Unit of University of East Anglia, United Kingdom. Firstly, we carried out Time Series Analysis of SSN and Geomagnetic aa-index spanning from 1950 to 2016. Secondly, we performed Regression Analysis on both solar activity data and climate variables to estimate the impact of solar magnetic activity on the Wet Zone West African climate. The Time Series Analysis showed that SSN variation was in-phase with Geomagnetic aa-index in all the solar cycles studied. Thus, Geomagnetic aa-index can be used as a proxy for studying solar magnetic activities. Performance of Regression Analysis showed that SSN regressed on SAT and Rainfall amounted to an average of 0.49 and 0.02% respectively throughout Solar Cycles 22–24. Furthermore, a regression of Geomagnetic aa-index on SAT and Rainfall yielded an average of 0.145 and 0.125% respectively. Our models showed that the variability of SAT and Rainfall in Wet Zone West Africa during Solar Cycles 22–24 are far less than 1%. Hence, the influence of SSN and Geomagnetic aa-index on SAT and Rainfall is less than 1%; and could cause ‘very small’ effect. These weak impacts are proofs that the variability of SAT and Rainfall were most probably not effected by SSN and Geomagnetic aa-index. Consequently, the variability of SAT and Rainfall in Wet Zone West Africa could not be attributed to SSN and Geomagnetic aa-index. We therefore, attempt to conclude that climate variability in Wet Zone West Africa is most probably not driven by solar magnetic activity, but could be attributed to anthropogenic activities.

BackgroundHighly structured electroencephalography (EEG) oscillations can occur in adults during etomidate-induced general anesthesia, but the link between these two phenomena is poorly understood. Therefore, in the present study, we investigated the electroencephalogram dynamics of etomidate-induced loss of consciousness (LOC) in order to understand the neurological mechanism of etomidate-induced LOC.MethodsThis study is a prospective observational study. Etomidate-induced anesthesia was performed on eligible patients undergoing elective surgery. We analyzed EEG data from 20 patients who received etomidate for the induction of general anesthesia. We used power spectra and coherence methods to process and analyze the EEG data. Our study was based on 4-channel EEG recordings.ResultsCompared with the baseline (awake period), etomidate induced an increase in power in delta, theta, alpha and beta waves during LOC. Compared with the awake period, the delta-wave (1–4 Hz), alpha-wave(8–13 Hz), and theta-wave(4–8 Hz) coherence increased significantly during LOC, while the slow-wave (< 1 Hz) coherence decreased. However, the delta wave (1.0–4.0 Hz) during etomidate-induced LOC was more coherent than during the awake period (1.86–3.17 Hz, two-group test for coherence, p < 0.001).ConclusionsThe neural circuit mechanism of etomidate-induced LOC is closely related to the induction of oscillation in delta, theta, alpha and beta waves and the enhancement of delta-wave coherence.Trial registrationChiCTR1800017110