Si XII X-Ray Satellite Lines in Solar Flare Spectra

The temperature dependence of the Si XII n = 3 and 4 dielectronic satellite line features at 5.82 and 5.56 A, respectively, near the Si XIII 1s2-1s3p and 1s2-1s4p lines (5.681 and 5.405 A), is calculated using atomic data presented here. The resulting theoretical spectra are compared with solar flare spectra observed by the RESIK spectrometer on the CORONAS-F spacecraft. The satellites, like the more familiar n = 2 satellites near the Si XIII 1s2-1s2p lines, are formed mostly by dielectronic recombination, but unlike the n = 2 satellites, are unblended. The implications for similar satellite lines in flare Fe spectra are discussed

Solar Flare Abundances of Potassium, Argon, and Sulphur

The absolute coronal abundances of potassium has been determined for the first time from X-ray solar flare line and continuous spectra together with absolute and relative abundances of Ar and S. Potassium is of importance in the continuing debate concerning the nature of the coronal/photospheric element abundance ratios which are widely considered to depend on first ionization potential since it has the lowest FIP of any common element in the Sun. The measurements were obtained with the RESIK crystal spectrometer on the Coronas-F spacecraft. A differential emission measure DEM = const. x exp (-(beta)T(sub e) was found to be the most consistent with the data out of three models considered. We find that the coronal ratio [K/H] = 3.7 x 10(exp - 7), a factor 3 times photospheric, in agreement with other observations using line-to-line ratios. Our measured value for the coronal ratio [Ar/H] = 1.5 x 10(exp -6) is significantly less than photospheric, indicating that there is a slight depletion of this high-FIP element in the corona. For S (an intermediate-FIP element) we obtained [S/H] = 2.2 x 10(exp - 5), approximately the same as in previous work

Varying Calcium Abundances in Solar Flares seen by Solar Maximum Mission

We report on calcium abundance $A({\rm Ca})$ estimates during the decay phases of 194 solar X-ray flares using archived data from the Bent Crystal Spectrometer (BCS) on Solar Maximum Mission (operational 1980~--~1989). The abundances are derived from the ratio of the total calcium X-ray line emission in BCS channel~1 to that in neighboring continuum, with temperature from a satellite-to-resonance line ratio. Generally the calcium abundance is found to be about three times the photospheric abundance, as previously found, indicating a ``FIP'' (first ionization potential) effect for calcium which has a relatively low FIP value. The precision of the abundance estimates (referred to hydrogen on a logarithmic scale with $A({\rm H}) = 12$), is typically $\sim \pm 0.01$, enabling any time variations of $A({\rm Ca})$ during the flare decay to be examined. For a total of 270 short time segments with $A({\rm Ca})$ determined to better than 2.3\% accuracy, many (106; 39\%) showed variations in $A({\rm Ca})$ at the $3\sigma$ level. For the majority, 74 (70\%) of these 106 segments $A({\rm Ca})$ decreased with time, and for 32 (30\%) $A({\rm Ca})$ increased with time. For 79 out of 270 (29\%) we observed constant or nearly constant $A({\rm Ca})$, and the remaining 85 (31\%) with irregular time behavior. A common feature was the presence of discontinuities in the time behavior of $A({\rm Ca})$. Relating these results to the ponderomotive force theory of Laming, we attribute the nature of varying $A({\rm Ca})$ to the emergence of loop structures in addition to the initial main loop, each with its characteristic calcium abundance.Comment: Astrophysical Journal (to be published). 14 pages with 8 figure

Non-Equilibrium Processes in the Solar Corona, Transition Region, Flares, and Solar Wind \textit{(Invited Review)}

We review the presence and signatures of the non-equilibrium processes, both non-Maxwellian distributions and non-equilibrium ionization, in the solar transition region, corona, solar wind, and flares. Basic properties of the non-Maxwellian distributions are described together with their influence on the heat flux as well as on the rates of individual collisional processes and the resulting optically thin synthetic spectra. Constraints on the presence of high-energy electrons from observations are reviewed, including positive detection of non-Maxwellian distributions in the solar corona, transition region, flares, and wind. Occurrence of non-equilibrium ionization is reviewed as well, especially in connection to hydrodynamic and generalized collisional-radiative modelling. Predicted spectroscopic signatures of non-equilibrium ionization depending on the assumed plasma conditions are summarized. Finally, we discuss the future remote-sensing instrumentation that can be used for detection of these non-equilibrium phenomena in various spectral ranges.Comment: Solar Physics, accepte

Dielectric spectroscopy of pressurized Saccharomyces cerevisiae

Results of broadband dielectric spectroscopy (BDS) in Saccharomyces cerevisiae (baker’s yeast), in situ as the function of pressure are presented. They show a clear evidence of a threshold to the new pattern of the pressure evolution of the static dielectric permittivity and DC electric conductivity already for P t  ≈ 200MPa at T = 5o C and P t  ≈ 300MPa at T = 25o C. BDS monitoring versus pressure tests up to P = 400MPa revealed particularly notable changes of properties after 30 minutes of compressing. Finally, the correlation between the amount of the spectrophotometric maximum absorbance and the DC electric conductivity was found. All these indicate significance of BDS as the tool for testing of pressure properties of cells assemblies, model foods etc., in situ under high pressures

Successful elimination of non-neural cells and unachievable elimination of glial cells by means of commonly used cell culture manipulations during differentiation of GFAP and SOX2 positive neural progenitors (NHA) to neuronal cells

<p>Abstract</p> <p>Background</p> <p>Although extensive research has been performed to control differentiation of neural stem cells – still, the response of those cells to diverse cell culture conditions often appears to be random and difficult to predict. To this end, we strived to obtain stabilized protocol of NHA cells differentiation – allowing for an increase in percentage yield of neuronal cells.</p> <p>Results</p> <p>Uncommitted GFAP and SOX2 positive neural progenitors – so-called, Normal Human Astrocytes (NHA) were differentiated in different environmental conditions to: only neural cells consisted of neuronal [MAP2+, GFAP-] and glial [GFAP+, MAP2-] population, non-neural cells [CD44+, VIMENTIN+, FIBRONECTIN+, MAP2-, GFAP-, S100β-, SOX2-], or mixture of neural and non-neural cells.</p> <p>In spite of successfully increasing the percentage yield of glial and neuronal <it>vs</it>. non-neural cells by means of environmental changes, we were not able to increase significantly the percentage of neuronal (GABA-ergic and catecholaminergic) over glial cells under several different cell culture testing conditions. Supplementing serum-free medium with several growth factors (SHH, bFGF, GDNF) did not radically change the ratio between neuronal and glial cells – i.e., 1,1:1 in medium without growth factors and 1,4:1 in medium with GDNF, respectively.</p> <p>Conclusion</p> <p>We suggest that biotechnologists attempting to enrich <it>in vitro </it>neural cell cultures in one type of cells – such as that required for transplantology purposes, should consider the strong limiting influence of intrinsic factors upon extracellular factors commonly tested in cell culture conditions.</p

KORTES Mission for Solar Activity Monitoring Onboard International Space Station

peer reviewedWe present a description of the recent advances in the development of the KORTES assembly—the first solar oriented mission designed for the Russian segment of the International Space Station. KORTES consists of several imaging and spectroscopic instruments collectively covering a wide spectral range extending from extreme ultraviolet (EUV) wavelengths to X-rays. The EUV telescopes inside KORTES will trace the origin and dynamics of various solar phenomena, e.g., flares, CMEs, eruptions etc. EUV spectra provided by grazing-incidence spectroheliographs will enable precise DEM-diagnostics during these events. The monochromatic X-ray imager will observe the formation of hot plasma in active regions and outside them. The SolpeX module inside KORTES will offer an opportunity to measure fluxes, Doppler shifts and polarization of soft X-ray emission both in lines and continuum. SolpeX observations will contribute to studies of particle beams and chromospheric evaporation. The instrumentation of KORTES will employ a variety of novel multilayer and crystal optics. The deployment of KORTES is planned for 2024

Arrested neural and advanced mesenchymal differentiation of glioblastoma cells-comparative study with neural progenitors

<p>Abstract</p> <p>Background</p> <p>Although features of variable differentiation in glioblastoma cell cultures have been reported, a comparative analysis of differentiation properties of normal neural GFAP positive progenitors, and those shown by glioblastoma cells, has not been performed.</p> <p>Methods</p> <p>Following methods were used to compare glioblastoma cells and GFAP+NNP (NHA): exposure to neural differentiation medium, exposure to adipogenic and osteogenic medium, western blot analysis, immunocytochemistry, single cell assay, BrdU incorporation assay. To characterize glioblastoma cells <it>EGFR </it>amplification analysis, LOH/MSI analysis, and <it>P53 </it>nucleotide sequence analysis were performed.</p> <p>Results</p> <p><it>In vitro </it>differentiation of cancer cells derived from eight glioblastomas was compared with GFAP-positive normal neural progenitors (GFAP+NNP). Prior to exposure to differentiation medium, both types of cells showed similar multilineage phenotype (CD44+/MAP2+/GFAP+/Vimentin+/Beta III-tubulin+/Fibronectin+) and were positive for SOX-2 and Nestin. In contrast to GFAP+NNP, an efficient differentiation arrest was observed in all cell lines isolated from glioblastomas. Nevertheless, a subpopulation of cells isolated from four glioblastomas differentiated after serum-starvation with varying efficiency into derivatives indistinguishable from the neural derivatives of GFAP+NNP. Moreover, the cells derived from a majority of glioblastomas (7 out of 8), as well as GFAP+NNP, showed features of mesenchymal differentiation when exposed to medium with serum.</p> <p>Conclusion</p> <p>Our results showed that stable co-expression of multilineage markers by glioblastoma cells resulted from differentiation arrest. According to our data up to 95% of glioblastoma cells can present <it>in vitro </it>multilineage phenotype. The mesenchymal differentiation of glioblastoma cells is advanced and similar to mesenchymal differentiation of normal neural progenitors GFAP+NNP.</p