Quasi-periodic pulsations in the gamma-ray emission of a solar flare

Quasi-periodic pulsations (QPPs) of gamma-ray emission with a period of about 40 s are found in a single loop X-class solar flare on 2005 January 1 at photon energies up to 2-6 MeV with the SOlar Neutrons and Gamma-rays (SONG) experiment aboard the CORONAS-F mission. The oscillations are also found to be present in the microwave emission detected with the Nobeyama Radioheliograph, and in the hard X-ray and low energy gamma-ray channels of RHESSI. Periodogram and correlation analysis shows that the 40 s QPPs of microwave, hard X-ray, and gamma-ray emission are almost synchronous in all observation bands. Analysis of the spatial structure of hard X-ray and low energy (80-225 keV) gamma-ray QPP with RHESSI reveals synchronous while asymmetric QPP at both footpoints of the flaring loop. The difference between the averaged hard X-ray fluxes coming from the two footpoint sources is found to oscillate with a period of about 13 s for five cycles in the highest emission stage of the flare. The proposed mechanism generating the 40 s QPP is a triggering of magnetic reconnection by a kink oscillation in a nearby loop. The 13 s periodicity could be produced by the second harmonics of the sausage mode of the flaring loop

Properties of quasi-periodic pulsations in solar flares from a single active region

We investigate the properties of a set of solar flares originating from a single active region (AR) that exhibit QPPs, and look for signs of the QPP periods relating to AR properties. The AR studied, best known as NOAA 12192, was unusually long-lived and produced 181 flares. Data from the GOES, EVE, Fermi, Vernov and NoRH observatories were used to determine if QPPs were present in the flares. For the soft X-ray GOES and EVE data, the time derivative of the signal was used. Power spectra of the time series data (without any form of detrending) were inspected, and flares with a peak above the 95% confidence level in the spectrum were labelled as having candidate QPPs. The confidence levels were determined taking account of uncertainties and the possible presence of red noise. AR properties were determined using HMI line of sight magnetograms. A total of 37 flares (20% of the sample) show good evidence of having QPPs, and some of the pulsations can be seen in data from multiple instruments and in different wavebands. The QPP periods show a weak correlation with the flare amplitude and duration, but this may be due to an observational bias. A stronger correlation was found between the QPP period and duration of the QPP signal, which can be partially but not entirely explained by observational constraints. No correlations were found with the AR area, bipole separation, or average magnetic field strength. The fact that a substantial fraction of the flare sample showed evidence of QPPs using a strict detection method with minimal processing of the data demonstrates that these QPPs are a real phenomenon, which cannot be explained by the presence of red noise or the superposition of multiple unrelated flares. The lack of correlation between the QPP periods and AR properties implies that the small-scale structure of the AR is important, and/or that different QPP mechanisms act in different cases.Comment: 23 pages, 57 figures. Accepted for publication by Astronomy & Astrophysic

Quasi-periodic pulsations in the gamma-ray emission of a solar flare

Copyright © 2010 American Astronomical Society / IOP PublishingQuasi-periodic pulsations (QPPs) of gamma-ray emission with a period of about 40 s are found in a single loop X-class solar flare on 2005 January 1 at photon energies up to 2-6 MeV with the SOlar Neutrons and Gamma-rays (SONG) experiment aboard the CORONAS-F mission. The oscillations are also found to be present in the microwave emission detected with the Nobeyama Radioheliograph, and in the hard X-ray and low energy gamma-ray channels of RHESSI. Periodogram and correlation analysis shows that the 40 s QPPs of microwave, hard X-ray, and gamma-ray emission are almost synchronous in all observation bands. Analysis of the spatial structure of hard X-ray and low energy (80-225 keV) gamma-ray QPP with RHESSI reveals synchronous while asymmetric QPP at both footpoints of the flaring loop. The difference between the averaged hard X-ray fluxes coming from the two footpoint sources is found to oscillate with a period of about 13 s for five cycles in the highest emission stage of the flare. The proposed mechanism generating the 40 s QPP is a triggering of magnetic reconnection by a kink oscillation in a nearby loop. The 13 s periodicity could be produced by the second harmonics of the sausage mode of the flaring loop

Type II Radio Emission and Solar Particle Observations

The 28 October 2003 flare gave us the unique opportunity to compare the acceleration time of high-energy protons with the escaping time of those particles which have been measured onboard spacecraft and by neutron monitors network as GLE event. High-energy emission time scale and shock wave height and velocity time dependencies were also studied.Comment: International Journal of Modern Physics A, Volume 20, Issue 29, pp. 6705-6707 (2005

Структурная биология липоксигеназ: настоящее и перспективы развития

Lipoxygenases (LOX) form a heterogeneous family of lipid peroxidizing enzymes, which have been implicated in the synthesis of inflammatory mediators. The involvement of LOX isoenzymes in regulation of physiological homeostasis and pathogenesis of various diseases with major health and political relevance made them potential targets for pharmacological intervention. Although the first plant lipoxygenase (soybean LOX1) was discovered more than 60 years ago, the structural aspects of these enzymes were not studied until the mid 1990s. For the time being the crystal structures of various lipoxygenase-isoforms have been reported, and X-ray coordinates for numerous enzyme-ligand complexes are also available. This review focuses on recent developments in molecular enzymology of LOX and summarizes our current knowledge on the structural basis of LOX catalysis. Hypotheses explaining the reaction specificity of different isoforms as well as evolutionary aspects are reviewed and discussed. As the review is mainly intended to cover thematic priorities, which have not been reviewed in the past, a detailed discussion of the biological function of LOX goes beyond the scope of this review.Липоксигеназы (LOX) - ферменты перекисного окисления липидов - вовлечены в патогенез воспалительных и гиперпролиферативных реакций организма. Несмотря на то, что первая липоксигеназа растительного происхождения (LOX1 сои) была обнаружена более 60 лет назад, структурная биология этой группы ферментов не изучалась вплоть до середины 1990-ых годов. Данный обзор посвящен новейшим аспектам в области изучения молекулярной энзимологии липоксигеназ и обобщает существующие в настоящее время представления о структурных основах катализа с их участием. В обзоре рассмотрены различные гипотезы, объясняющие реакционную специфичность LOX, а также подведен промежуточный итог в области знания об эволюционном развитии этого класса ферментов в различных организмах. Несмотря на то, что биологическая роль LOX в низших организмах далеко не ясна, наличие в их ДНК последовательности LOX позволяет предположить, что семейство этих ферментов могло возникнуть сразу после появления атмосферного кислорода на Земле

Study of humoral immunity indices for assessing physical exhaustion in sports

Studies of real opportunities for physical skills of athletes sufficiently depend on their adaptive potential for increasing physical loads. Extreme physical and psychoemotional loads may lead to overwork and decreased physical ability in professional sportsmen. These adaptation processes are regulated by the main biochemical systems of the body. A special role belongs to the factors of humoral immunity, i.e., natural antibodies, which are a component of innate immunity. They circulate in blood of healthy persons in absence of obvious antigenic stimulation. Analytical techniques for measuring the level of natural antibodies that reflect the state of the system of endogenous bioregulators involved into the molecular mechanisms of adaptation process have been developed. An important role among them is played by the regulators of the opioid system β-endorphin and orphanin. The biochemical and immunological parameters were determined in 10 athletes active in figure skating (Master of Sports), whose average age was 16±0.4 years, and sport experience of 9±1 years. The duration of the study was divided into 5 stages and was 62 days. During the dynamic observations in the course of intensive training, no clear shifts in biochemical parameters were revealed towards adaptation stress and delayed recovery. The level of natural antibodies to orphanin and beta-endorphin was measured in the athletes blood serum by ELISA techique. It is found that each athlete is characterized by individual immune profile. At the initial stage of the examination, the level of antibodies to beta-endorphin was within normal ranges, except for its decrease in one athlete. The level of antibodies to orphanin in majority of cases was higher than normal, probably, due to inhibitory control of the pain signal. Further study in time dynamics revealed that the immunological parameters, natural antibodies to opioid peptides, change in accordance with the state of adaptation resources in the athletes. These indexes reflect psycho-emotional potential and pain tolerance threshold for athletes from the start of training and throughout the entire period. Therefore, from a prognostic point of view, it is important to monitor the content of natural antibodies to beta-endorphin and orphanin in athletes in the course of training. Such individual monitoring of the athlete’s immunological indices allows us to select a more effective, personal training program

Complex ultrasound diagnostic assessment of the results of neoadjuvant chemotherapy for locally advanced cervical cancer (Stages IIB–IIIB)

Background. Current complex ultrasound diagnosis using novel imaging techniques can assess, to a high accuracy, different tumor parameters during neoadjuvant chemotherapy (NCT) for locally advanced cervical cancer (CC) (Stages IIB–IIB). This assessment is very important and necessary to define further treatment policy.Materials and methods. A total of 199 patients diagnosed with Stages IIB–IIIB CC, including 60 patients with Stage IIB (T2bN0M0), 4 with Stage IIIА (T3aN0M0), and 135 with Stage IIIВ (T2bN1M0, T3aN1M0, T3bN0–1M0) (according to the International Federationof Gynecology and Obstetrics (FIGO) classification), who received NCT at Stage 1 of treatment, were examined. Complex ultrasound study was conducted before treatment initiation and after each NCT cycle. The therapeutic pathomorphism of a tumor was evaluated in surgically treated patients.Results. The criteria have been determined for evaluating the efficiency of NCT for locally advanced CC, which are based on current ultrasonographic techniques including B-mode, Doppler ultrasound (power, spectral, three-dimensional ones), as well as on the results of therapeutic pathomorphism.Conclusion. The criteria for evaluating the efficiency of NCT for CC should be based on current complex ultrasonographic techniques