About the stabilization of the dendritic structure of GG brand copper powder

In industry copper powder is recieved under constant current load. Surface roughening occurs during evolution of the dendritic particles. It is suggested to create a new impulse of current equal to the initial current density of 3200 A/m2 in order to obtain uniform structure of the precipitate. Current load was evaluated by the result of chronopotentiometry research of the dynamics of the dendritic precipitate on cylindrical electrode. Four-impulse galvanostatic electrolysis was investigated for the copper powder GG. New current impulse shifts the electrode potential to the cathodic area, crystallization process flows more rapidly.This work was done under financial support from RFBR № 11-03-002296

Quasi-Periodic Pulsations in Solar Flares: new clues from the Fermi Gamma-Ray Burst Monitor

In the last four decades it has been observed that solar flares show quasi-periodic pulsations (QPPs) from the lowest, i.e. radio, to the highest, i.e. gamma-ray, part of the electromagnetic spectrum. To this day, it is still unclear which mechanism creates such QPPs. In this paper, we analyze four bright solar flares which show compelling signatures of quasi-periodic behavior and were observed with the Gamma-Ray Burst Monitor (\gbm) onboard the Fermi satellite. Because GBM covers over 3 decades in energy (8 keV to 40 MeV) it can be a key instrument to understand the physical processes which drive solar flares. We tested for periodicity in the time series of the solar flares observed by GBM by applying a classical periodogram analysis. However, contrary to previous authors, we did not detrend the raw light curve before creating the power spectral density spectrum (PSD). To assess the significance of the frequencies we made use of a method which is commonly applied for X-ray binaries and Seyfert galaxies. This technique takes into account the underlying continuum of the PSD which for all of these sources has a P(f) ~ f^{-\alpha} dependence and is typically labeled red-noise. We checked the reliability of this technique by applying it to a solar flare which was observed by the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) which contains, besides any potential periodicity from the Sun, a 4 s rotational period due to the rotation of the spacecraft around its axis. While we do not find an intrinsic solar quasi-periodic pulsation we do reproduce the instrumental periodicity. Moreover, with the method adopted here, we do not detect significant QPPs in the four bright solar flares observed by GBM. We stress that for the purpose of such kind of analyses it is of uttermost importance to appropriately account for the red-noise component in the PSD of these astrophysical sources.Comment: accepted by A&

Pathomorphological changes in pulmonary vessels at different terms of lethal outcomes of patients with COVID-19

Objective: to study the pathomorphological changes in the vessels of the lungs at different times of death in patients with COVID-19. Material and methods: autopsy protocols of 40 deaths from COVID-19 with histological, histochemical examination, and photoregistration. To determine the degree of pulmonary vascular lesions, the authors developed and applied a semi-quantitative assessment scale for the sign based on counting the affected lung vessels in 10 fields of view, expressed as a percentage: no sign – (0%), weak sign + (1-25%), moderate sign ++ (26-50%), expressed sign +++ (51-75%), highly expressed sign ++++ (76-100%). Results: during the first 14 days of the disease, stasis and swelling of individual endotheliocytes were noted in the vessels of the microvasculature. After 15-21 days of the development of COVID-19, signs of alterations in endothelial cells and microthrombosis were observed in microvessels. After 22-28 days of the disease, the phenomena of repair and hyperplasia of endothelial cells were detected. At different times of the development of the disease in the lung tissue, the phenomena of acute respiratory distress syndrome, interstitial pneumonia, and focal pneumofibrosis were observed. Conclusions: the authors believe that COVID-19 is associated with a progressive microvascular endotheliopathy in the lungs which is characterized by swelling, alteration, and later, by hyperplasia, and regeneration of endothelial cells in combination with microthrombosis. Destructive changes in the walls of the microvessels of the lungs have superficial character without the destruction of the reticular frame and basal membranes. Endotheliopathy, microthrombus formation of microvessels of the lungs, and interstitial pneumonia create a vicious circle of severe respiratory failure, which must be taken into account in the clinic to correct the treatment of patients with COVID-19

ОСОБЕННОСТИ ЦЕРЕБРАЛЬНОГО МЕТАБОЛИЗМА ГЛЮКОЗЫ У БОЛЬНЫХ С СОСУДИСТОЙ ДЕМЕНЦИЕЙ (ПО ДАННЫМ ПОЗИТРОННО-ЭМИССИОННОЙ ТОМОГРАФИИ)

Vascular dementia is quite common diagnosis in elderly patients (5–10% of all dementia cases). Despite that, where is no reliable neuroimaging diagnostic marker like patterns of cerebral glucose metabolism changes in positron emission tomography (PET) in Alzheimer’s disease and some other types of dementia. The purpose of this research was to study cerebral glucose metabolism peculiarities with PET and to compare findings with metabolic changes in normal aging. Two groups of subjects were examined: patients suffered from vascular dementia and age-matching control group without cognitive and neurological disorders. Cerebral glucose hypometabolism in vascular dementia was heterogeneous and differed in different patients. Besides that, comparison with the control group demonstrated larger volume of hypometabolism and statistically significant decrease of cerebral metabolism in parietal, frontal and cingular cortex. Сосудистые деменции составляют 5–10% всех известных случаев деменции. При этом для нее не существует надежного диагностического маркера, основанного на применении методов нейровизуализации, как, например, паттерны нарушений церебрального метаболизма при болезни Альцгеймера и некоторых других видов деменции по данным позитронно-эмиссионной томографии (ПЭТ). Целью данного исследования было изучение особенностей церебрального метаболизма у больных сосудистой деменцией по данным ПЭТ и сравнение их с наблюдающимися при нормальном старении возрастными изменениями. Обследовано две группы: группа больных сосудистой деменцией и контрольная группа «возрастной нормы», сопоставимая по возрасту. При сосудистой деменции выявлялся неоднородный рисунок гипометаболизма, различавшийся у разных больных. Вместе с тем сравнение с контрольной группой обнаружило при сосудистой деменции больший объем гипометаболизма и статистически значимое снижение церебрального метаболизма глюкозы в ассоциативной теменной, лобной и поясной коре.

Multiwavelength studies of MHD waves in the solar chromosphere: An overview of recent results

The chromosphere is a thin layer of the solar atmosphere that bridges the relatively cool photosphere and the intensely heated transition region and corona. Compressible and incompressible waves propagating through the chromosphere can supply significant amounts of energy to the interface region and corona. In recent years an abundance of high-resolution observations from state-of-the-art facilities have provided new and exciting ways of disentangling the characteristics of oscillatory phenomena propagating through the dynamic chromosphere. Coupled with rapid advancements in magnetohydrodynamic wave theory, we are now in an ideal position to thoroughly investigate the role waves play in supplying energy to sustain chromospheric and coronal heating. Here, we review the recent progress made in characterising, categorising and interpreting oscillations manifesting in the solar chromosphere, with an impetus placed on their intrinsic energetics.Comment: 48 pages, 25 figures, accepted into Space Science Review

An Inside Look at Sunspot Oscillations with Higher Azimuthal Wavenumbers

Solar chromospheric observations of sunspot umbrae offer an exceptional view of magneto-hydrodynamic wave phenomena. In recent years, a wealth of wave signatures related to propagating magneto-acoustic modes have been presented, which demonstrate complex spatial and temporal structuring of the wave components. Theoretical modelling has demonstrated how these ubiquitous waves are consistent with an m=0 slow magneto-acoustic mode, which are excited by trapped sub-photospheric acoustic (p-mode) waves. However, the spectrum of umbral waves is broad, suggesting that the observed signatures represent the superposition of numerous frequencies and/or modes. We apply Fourier filtering, in both spatial and temporal domains, to extract chromospheric umbral wave characteristics consistent with an m=1 slow magneto-acoustic mode. This identification has not been described before. Angular frequencies of 0.037 +/- 0.007 rad/s (2.1 +/- 0.4 deg/s), corresponding to a period approximately 170 s for the m=1 mode are uncovered for spatial wavenumbers in the range of 0.45<k<0.90 arcsec^-1 (5000-9000 km). Theoretical dispersion relations are solved, with corresponding eigenfunctions computed, which allows the density perturbations to be investigated and compared with our observations. Such magnetohydrodynamic modelling confirms our interpretation that the identified wave signatures are the first direct observations of an m=1 slow magneto-acoustic mode in the chromospheric umbra of a sunspot

The Frequency-dependent Damping of Slow Magnetoacoustic Waves in a Sunspot Umbral Atmosphere

High spatial and temporal resolution images of a sunspot, obtained simultaneously in multiple optical and UV wavelengths, are employed to study the propagation and damping characteristics of slow magnetoacoustic waves up to transition region heights. Power spectra are generated from intensity oscillations in sunspot umbra, across multiple atmospheric heights, for frequencies up to a few hundred mHz. It is observed that the power spectra display a power-law dependence over the entire frequency range, with a significant enhancement around 5.5 mHz found for the chromospheric channels. The phase-difference spectra reveal a cutoff frequency near 3 mHz, up to which the oscillations are evanescent, while those with higher frequencies propagate upwards. The power-law index appears to increase with atmospheric height. Also, shorter damping lengths are observed for oscillations with higher frequencies suggesting frequency-dependent damping. Using the relative amplitudes of the 5.5 mHz (3 minute) oscillations, we estimate the energy flux at different heights, which seems to decay gradually from the photosphere, in agreement with recent numerical simulations. Furthermore, a comparison of power spectra across the umbral radius highlights an enhancement of high-frequency waves near the umbral center, which does not seem to be related to magnetic field inclination angle effects

Forward modeling of standing kink modes in coronal loops. I. Synthetic views

Kink magnetohydrodynamic (MHD) waves are frequently observed in various magnetic structures of the solar atmosphere. They may contribute significantly to coronal heating and could be used as a tool to diagnose the solar plasma. In this study, we synthesize the Fe ix λ171.073 emission of a coronal loop supporting a standing kink MHD mode. The kink MHD wave solution of a plasma cylinder is mapped into a semi-torus structure to simulate a curved coronal loop. We decompose the solution into a quasi-rigid kink motion and a quadrupole term, which dominate the plasma inside and outside of the flux tube, respectively. At the loop edges, the line of sight integrates relatively more ambient plasma, and the background emission becomes significant. The plasma motion associated with the quadrupole term causes spectral line broadening and emission suppression. The periodic intensity suppression will modulate the integrated intensity and the effective loop width, which both exhibit oscillatory variations at half of the kink period. The quadrupole term can be directly observed as a pendular motion at the front view

Coronal Density and Temperature Profiles Calculated by Forward Modeling EUV Emission Observed by SDO/AIA

We present a model for the intensity of optically thin extreme ultraviolet (EUV) emission for a plasma atmosphere. We apply our model to the solar corona as observed using the six optically thin EUV channels of the Solar Dynamics Observatory/Atmospheric Imaging Assembly instrument. The emissivity of the plasma is calculated from the density and temperature using CHIANTI tables and the intensity is then determined by integration along the line of sight. We consider several different profiles for the radial density and temperature profiles, each of which are constrained by the observational data alone with no further physical assumptions. We demonstrate the method first by applying it to a quiet region of the corona, and then use it as the background component of a model including coronal holes, allowing the plasma densities and temperatures inside and outside the hole to be estimated. We compare our results with differential emission measure inversions. More accurate estimates for the coronal density and temperature profiles have the potential to help constrain plasma properties such as the magnetic field strength when used in combination with methods such as seismology

Genomics and proteomics approaches to the study of cancer-stroma interactions

<p>Abstract</p> <p>Background</p> <p>The development and progression of cancer depend on its genetic characteristics as well as on the interactions with its microenvironment. Understanding these interactions may contribute to diagnostic and prognostic evaluations and to the development of new cancer therapies. Aiming to investigate potential mechanisms by which the tumor microenvironment might contribute to a cancer phenotype, we evaluated soluble paracrine factors produced by stromal and neoplastic cells which may influence proliferation and gene and protein expression.</p> <p>Methods</p> <p>The study was carried out on the epithelial cancer cell line (Hep-2) and fibroblasts isolated from a primary oral cancer. We combined a conditioned-medium technique with subtraction hybridization approach, quantitative PCR and proteomics, in order to evaluate gene and protein expression influenced by soluble paracrine factors produced by stromal and neoplastic cells.</p> <p>Results</p> <p>We observed that conditioned medium from fibroblast cultures (FCM) inhibited proliferation and induced apoptosis in Hep-2 cells. In neoplastic cells, 41 genes and 5 proteins exhibited changes in expression levels in response to FCM and, in fibroblasts, 17 genes and 2 proteins showed down-regulation in response to conditioned medium from Hep-2 cells (HCM). Nine genes were selected and the expression results of 6 down-regulated genes (<it>ARID4A</it>, <it>CALR</it>, <it>GNB2L1</it>, <it>RNF10</it>, <it>SQSTM1</it>, <it>USP9X</it>) were validated by real time PCR.</p> <p>Conclusions</p> <p>A significant and common denominator in the results was the potential induction of signaling changes associated with immune or inflammatory response in the absence of a specific protein.</p