Radio emission from acceleration sites of solar flares

The Letter takes up a question of what radio emission is produced by electrons at the very acceleration site of a solar flare. Specifically, we calculate incoherent radio emission produced within two competing acceleration models--stochastic acceleration by cascading MHD turbulence and regular acceleration in collapsing magnetic traps. Our analysis clearly demonstrates that the radio emission from the acceleration sites: (i) has sufficiently strong intensity to be observed by currently available radio instruments and (ii) has spectra and light curves which are distinctly different in these two competing models, which makes them observationally distinguishable. In particular, we suggest that some of the narrowband microwave and decimeter continuum bursts may be a signature of the stochastic acceleration in solar flares.Comment: ApJL, in pres

Magnetic field and unstable accretion during AM Herculis low states

A study of AM Her low states in September 1990 and 1991 and June-July 1997 is reported from a coordinated campaign with observations obtained at the Haute-Provence observatory, at the 6-m telescope of the Special Astrophysical Observatory and at the 2.6m and 1.25m telescopes of the Crimean observatory. Spectra obtained at different dates when the source was in low states at a comparable V magnitude, show the presence of strong Zeeman absorption features and marked changes in emission lines with a day-to-day reappearance of the HeII (4686\AA) emission lines in 1991. Despite this variability, the magnetic field inferred from the fitting of the absorption spectrum with Zeeman hydrogen splitting, is remarkably constant with a best value of (12.5$\pm$0.5)MG. Detailed analysis of the UBVRI light curves shows the presence of repetitive moderate amplitude ($\sim$ 0.3-0.5 mag) flares predominantly red in colour. These flares are attributed to small accretion events and are compared to the large ($\sim$ 2 mag.) blue flare reported by Shakhovskoy et al. (1993). We suggest that the general flaring activity observed during the low states is generated by accretion events. The different characteristics of the flares (colour and polarization) are the results of different shock geometries depending on the net mass accretion flux.Comment: accepted in Astronomy & Astrophysics (Main Journal), 10 pages, 6 Figures, Late

Quality Assurance of Medicines: Main Scientific Approaches and Control Methods

The most important component of national health policy is the assurance of quality, efficacy, and safety of medicines entering the pharmaceutical market in the Russian Federation. In this interview, we have discussed the quality control of medicines; its interconnections with various branches of science, in particular, with analytical chemistry; and the matters of material and equipment supply with Elena L. Kovaleva (Doctor of Pharmaceutical Sciences, Deputy Director of the Centre for Medicinal Products Evaluation and Control of the Scientific Centre for Expert Evaluation of Medicinal Products of the Ministry of Health of the Russian Federation), Yuri A. Zolotov (Academician of the Russian Academy of Sciences, Full Professor, Doctor of Chemical Sciences), and Dmitry V. Somov (Candidate of Pharmaceutical Sciences, Acting Director General of the Information and Methodological Center for Expertise, Accounting, and Analysis of the Circulation of Medicinal Products of the Federal Service for Surveillance in Healthcare)

Modern Agricultural Market of Kyrgyzstan in the Aspect of Youth Problems

В статье проведен анализ перехода к рыночным отношениям в аграрном секторе экономики Кыргызстана, проанализированы каналы сбыта сельскохозяйственной продукции. Обоснована необходимость развития полноценного менеджмента и маркетинга в регулировании производства сельскохозяйственной продукции и рынка продовольствия. Дальнейшая эффективность такого производства связана с созданием в аграрном секторе маркетинговой службы, способствующей внедрению инновационного стиля жизни и повышению конкурентоспособности молодежи.This article analyzes the transition to market relations in the agricultural sector of the Kyrgyz economy, analyzes the marketing channels for agricultural products. The necessity of development of full-fledged management and marketing in the regulation of agricultural production and the food market has been substantiated. Further efficiency of agricultural production is associated with the creation of a marketing service in the agricultural sector, contributing to the introduction of an innovative lifestyle and increasing the competitiveness of young people

Small scale energy release driven by supergranular flows on the quiet Sun

In this article we present data and modelling for the quiet Sun that strongly suggest a ubiquitous small-scale atmospheric heating mechanism that is driven solely by converging supergranular flows. A possible energy source for such events is the power transfer to the plasma via the work done on the magnetic field by photospheric convective flows, which exert drag of the footpoints of magnetic structures. In this paper we present evidence of small scale energy release events driven directly by the hydrodynamic forces that act on the magnetic elements in the photosphere, as a result of supergranular scale flows. We show strong spatial and temporal correlation between quiet Sun soft X-ray emission (from <i>Yohkoh</i> and <i>SOHO</i> MDI-derived flux removal events driven by deduced photospheric flows. We also present a simple model of heating generated by flux submergence, based on particle acceleration by converging magnetic mirrors. In the near future, high resolution soft X-ray images from XRT on the <i>Hinode</i> satellite will allow definitive, quantitative verification of our results

Wave instabilities in an anisotropic magnetized space plasma

We study wave instability in an collisionless, rarefied hot plasma (e.g. solar wind or corona). We consider the anisotropy produced by the magnetic field, when the thermal gas pressures across and along the field become unequal. We apply the 16-moment transport equations (obtained from the Boltzmann-Vlasov kinetic equation) including the anisotropic thermal fluxes. The general dispersion relation for the incompressible wave modes is derived. It is shown that a new, more complex wave spectrum with stable and unstable behavior is possible, in contrast to the classic fire-hose modes obtained in terms of the 13-moment integrated equations.Comment: 5 pages, length reduced to that of a Research Note, A&A (in press

Conjugate Hard X-ray Footpoints in the 2003 October 29 X10 Flare: Unshearing Motions, Correlations, and Asymmetries

We present a detailed imaging and spectroscopic study of the conjugate hard X-ray (HXR) footpoints (FPs) observed with RHESSI in the 2003 October 29 X10 flare. The double FPs first move toward and then away from each other, mainly parallel and perpendicular to the magnetic neutral line, respectively. The transition of these two phases of FP unshearing motions coincides with the direction reversal of the motion of the loop-top (LT) source, and with the minima of the estimated loop length and LT height. The FPs show temporal correlations between HXR flux, spectral index, and magnetic field strength. The HXR flux exponentially correlates with the magnetic field strength, which also anti-correlates with the spectral index before the second HXR peak's maximum, suggesting that particle acceleration sensitively depends on the magnetic field strength and/or reconnection rate. Asymmetries are observed between the FPs: on average, the eastern FP is 2.2 times brighter in HXR flux and 1.8 times weaker in magnetic field strength, and moves 2.8 times faster away from the neutral line than the western FP; the estimated coronal column density to the eastern FP from the LT source is 1.7 times smaller. The two FPs have marginally different spectral indexes. The eastern-to-western FP HXR flux ratio and magnetic field strength ratio are anti-correlated only before the second HXR peak's maximum. Neither magnetic mirroring nor column density alone can explain the totality of these observations, but their combination, together with other transport effects, might provide a full explanation. We have also developed novel techniques to remove particle contamination from HXR counts and to estimate effects of pulse pileup in imaging spectroscopy, which can be applied to other RHESSI flares in similar circumstances.Comment: 22 pages, 14 figures, 4 tables; ApJ 2009, in pres