Correction of SOHO CELIAS/SEM EUV Measurements saturated by extreme solar flare events

The solar irradiance in the Extreme Ultraviolet (EUV) spectral bands has been observed with a 15 sec cadence by the SOHO Solar EUV Monitor (SEM) since 1995. During remarkably intense solar flares the SEM EUV measurements are saturated in the central (zero) order channel (0.1 -- 50.0 nm) by the flare soft X-ray and EUV flux. The first order EUV channel (26 -- 34 nm) is not saturated by the flare flux because of its limited bandwidth, but it is sensitive to the arrival of Solar Energetic Particles (SEP). While both channels detect nearly equal SEP fluxes, their contributions to the count rate is sensibly negligible in the zero order channel but must be accounted for and removed from the first channel count rate. SEP contribution to the measured SEM signals usually follows the EUV peak for the gradual solar flare events. Correcting the extreme solar flare SEM EUV measurements may reveal currently unclear relations between the flare magnitude, dynamics observed in different EUV spectral bands, and the measured Earth atmosphere response. A simple and effective correction technique based on analysis of SEM count-rate profiles, GOES X-ray, and GOES proton data has been developed and used for correcting EUV measurements for the five extreme solar flare events of July 14, 2000, October 28, November 2, November 4, 2003, and January 20, 2005. Although none of the 2000 and 2003 flare peaks were contaminated by the presence of SEPs, the January 20, 2005 SEPs were unusually prompt and contaminated the peak. The estimated accuracy of the correction is about 7.5% for large X-class events.Comment: To appear in Astron. Nachr. /A

A Change in the Solar He II EUV Global Network Structure as an Indicator of the Geo-Effectiveness of Solar Minima

Solar activity during 2007 - 2009 was very low, causing anomalously low thermospheric density. A comparison of solar extreme ultraviolet (EUV) irradiance in the He II spectral band (26 to 34 nm) from the Solar Extreme ultraviolet Monitor (SEM), one of instruments on the Charge Element and Isotope Analysis System (CELIAS) on board the Solar and Heliospheric Observatory (SOHO) for the two latest solar minima showed a decrease of the absolute irradiance of about 15 +/- 6 % during the solar minimum between Cycles 23 and 24 compared with the Cycle 22/23 minimum when a yearly running-mean filter was used. We found that some local, shorter-term minima including those with the same absolute EUV flux in the SEM spectral band show a higher concentration of spatial power in the global network structure from the 30.4 nm SOHO/Extreme ultraviolet Imaging Telescope (EIT) images for the local minimum of 1996 compared with the minima of 2008 - 2011.We interpret this higher concentration of spatial power in the transition region's global network structure as a larger number of larger-area features on the solar disk. These changes in the global network structure during solar minima may characterize, in part, the geo-effectiveness of the solar He II EUV irradiance in addition to the estimations based on its absolute levels

Extreme Ultraviolet Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO): Overview of Science Objectives, Instrument Design, Data Products, and Model Developments

The highly variable solar extreme ultraviolet (EUV) radiation is the major energy input to the Earth’s upper atmosphere, strongly impacting the geospace environment, affecting satellite operations, communications, and navigation. The Extreme ultraviolet Variability Experiment (EVE) onboard the NASA Solar Dynamics Observatory (SDO) will measure the solar EUV irradiance from 0.1 to 105 nm with unprecedented spectral resolution (0.1 nm), temporal cadence (ten seconds), and accuracy (20%). EVE includes several irradiance instruments: The Multiple EUV Grating Spectrographs (MEGS)-A is a grazing-incidence spectrograph that measures the solar EUV irradiance in the 5 to 37 nm range with 0.1-nm resolution, and the MEGS-B is a normal-incidence, dual-pass spectrograph that measures the solar EUV irradiance in the 35 to 105 nm range with 0.1-nm resolution. To provide MEGS in-flight calibration, the EUV SpectroPhotometer (ESP) measures the solar EUV irradiance in broadbands between 0.1 and 39 nm, and a MEGS-Photometer measures the Sun’s bright hydrogen emission at 121.6 nm. The EVE data products include a near real-time space-weather product (Level 0C), which provides the solar EUV irradiance in specific bands and also spectra in 0.1-nm intervals with a cadence of one minute and with a time delay of less than 15 minutes. The EVE higher-level products are Level 2 with the solar EUV irradiance at higher time cadence (0.25 seconds for photometers and ten seconds for spectrographs) and Level 3 with averages of the solar irradiance over a day and over each one-hour period. The EVE team also plans to advance existing models of solar EUV irradiance and to operationally use the EVE measurements in models of Earth’s ionosphere and thermosphere. Improved understanding of the evolution of solar flares and extending the various models to incorporate solar flare events are high priorities for the EVE team.United States. National Aeronautics and Space Administration (contract NAS5-02140

Случай семейной первичной цилиарной дискинезии без обратного расположения внутренних органов

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Associations of IL17A G-197A single nucleotide polymorphism with immunological parameters and structural changes of the brain in schizophrenia

Schizophrenia is a chronic mental disorder that is caused by a complex palette of genetic, epigenetic and environmental factors. Some of the important components of its pathogenesis are systemic inflammation and the dysfunction of immunity, which lead to neuroinflammation, contributing to development of structural brain changes. Earlier we have shown that increase in interleukin-17A levels is associated with morphometric changes and immune dysregulation in schizophrenia. IL17A G-197A (rs2275913) genetic polymorphism is involved in determining interleukin-17A secretion. The goal of this work was to investigate the associations between rs2275913 polymorphism, immune disorders and structural neurovisualization findings in schizophrenia to provide new insights into the immunopathogenesis of this disease. 60 patients aged 18 to 42 years diagnosed with schizophrenia were enrolled. 85 healthy volunteers were included into the control group. Multiplex assay was used to determine cytokine and chemokine serum levels. Rs2275913 polymorphism was assessed by polymerase chain reaction with electrophoretic detection of amplification products. A number of relationships between rs2275913 polymorphism and the immune parameters in schizophrenia were revealed. Carriers of G allele showed significant increase in IFNY, a key cytokine of Th1-link of adaptive immunity, and IL-8, an inflammatory chemokine. Also, increased levels of CXCL16 were observed in patients carrying the G allele. CXCL16 activates secretion of other proinflammatory chemokines and is involved in activation of Th1 adaptive immunity. Associations of heterozygous GA genotype with reduced cortical thickness in a number of areas of the frontal cortex in schizophrenia were found. Changes in cortical thickness in some of these areas, including middle frontal gyrus and orbitofrontal cortex, can be relevant to the pathogenesis of schizophrenia. The results highlight the importance of immunogenetic factors in the pathogenesis of schizophrenia and indicate that the rs2275913 polymorphism requires further studies as a potential biomarker of immune dysregulation and morphometric brain changes in schizophrenia

An Extreme Solar Event of 20 January 2005: Properties of the Flare and the Origin of Energetic Particles

The extreme solar and SEP event of 20 January 2005 is analyzed from two perspectives. Firstly, we study features of the main phase of the flare, when the strongest emissions from microwaves up to 200 MeV gamma-rays were observed. Secondly, we relate our results to a long-standing controversy on the origin of SEPs arriving at Earth, i.e., acceleration in flares, or shocks ahead of CMEs. All emissions from microwaves up to 2.22 MeV line gamma-rays during the main flare phase originated within a compact structure located just above sunspot umbrae. A huge radio burst with a frequency maximum at 30 GHz was observed, indicating the presence of a large number of energetic electrons in strong magnetic fields. Thus, protons and electrons responsible for flare emissions during its main phase were accelerated within the magnetic field of the active region. The leading, impulsive parts of the GLE, and highest-energy gamma-rays identified with pi^0-decay emission, are similar and correspond in time. The origin of the pi^0-decay gamma-rays is argued to be the same as that of lower energy emissions. We estimate the sky-plane speed of the CME to be 2000-2600 km/s, i.e., high, but of the same order as preceding non-GLE-related CMEs from the same active region. Hence, the flare itself rather than the CME appears to determine the extreme nature of this event. We conclude that the acceleration, at least, to sub-relativistic energies, of electrons and protons, responsible for both the flare emissions and the leading spike of SEP/GLE by 07 UT, are likely to have occurred simultaneously within the flare region. We do not rule out a probable contribution from particles accelerated in the CME-driven shock for the leading GLE spike, which seemed to dominate later on.Comment: 34 pages, 14 Postscript figures. Solar Physics, accepted. A typo corrected. The original publication is available at http://www.springerlink.co

Association of IL-17A levels with immuneinflammatory profile and structural MRI data in patients with schizophrenia

IL-17A is a proinflammatory cytokine involved in pathogenesis of some neuroinflammatory diseases of the brain. However, its role in schizophrenia is poorly understood. Currently, noninvasive neuroimaging techniques are widely used to assess abnormalities in brain morphology and interactions of neuronal networks in schizophrenia. The aim of this work was to study associations between IL-17A level and brain morphometric parameters in schizophrenia, in order to clarify immune factors of pathogenesis and search for biomarkers of unfavorable disease course. 45 patients with schizophrenia and 30 healthy volunteers were included into the study. The levels of cytokines (IL-5, IL-6, IL-8, IL-10, IL-17A) and inflammatory markers were determined by ELISA or multiplex analysis. MRI scans were performed with a Siemens Magnetom Verio 3T MRI scanner. We used Kruskal–Wallis test to assess significant differences in immunological parameters followed by Mann–Whitney paired comparison; Student test to assess the significance of differences in morphometric parameters of the brain; Fisher exact test to assess the differences in discrete variables, with the differences considered statistically significant at p < 0.05. IL-17A levels were found to be increased in schizophrenia. Its elevated content was associated with increased levels of C-reactive protein, IL-5, IL-6, IL-8, IL-10, and the presence of morphometric changes of frontal and temporal cortex in the patients. So far, the relationships between IL-17A levels, immunoinflammatory parameters and structural brain changes have not been studied in schizophrenia. In the present work, we found an association of elevated IL-17A levels with decreased cortical thickness in several brain regions, systemic inflammation and activation of Th2-link of adaptive immunity in the patients with schizophrenia. According to the literature, a number of brain areas, where cortical thickness was associated with IL-17A levels may be relevant to pathogenesis of the disease and, in particular, to the development of negative symptoms, including impoverishment of interests, speech, and emotions. The results are important for understanding the role of immune disorders in pathogenesis of schizophrenia, including structural changes of the brain, and suggest that IL-17A may be a biomarker of these disorders. Confirmation of associations between structural neuroimaging findings, laboratory markers of inflammation and immune disorders may provide the basis for new multidisciplinary approaches to the diagnosis and prognosis of schizophrenia

Buoyancy-driven Magnetohydrodynamic Waves

Turbulent motions close to the visible solar surface may generate low-frequency internal gravity waves (IGWs) that propagate through the lower solar atmosphere. Magnetic activity is ubiquitous throughout the solar atmosphere, so it is expected that the behavior of IGWs is to be affected. In this article we investigate the role of an equilibrium magnetic field on propagating and standing buoyancy oscillations in a gravitationally stratified medium. We assume that this background magnetic field is parallel to the direction of gravitational stratification. It is known that when the equilibrium magnetic field is weak and the background is isothermal, the frequencies of standing IGWs are sensitive to the presence of magnetism. Here, we generalize this result to the case of a slowly varying temperature. To do this, we make use of the Boussinesq approximation. A comparison between the hydrodynamic and magnetohydrodynamic cases allows us to deduce the effects due to a magnetic field. It is shown that the frequency of IGWs may depart significantly from the Brunt–Väisälä frequency, even for a weak magnetic field. The mathematical techniques applied here give a clearer picture of the wave mode identification, which has previously been misinterpreted. An observational test is urged to validate the theoretical findings