Azimuthal expansion of high-latitude auroral arcs

International audienceWe used the TV auroral observations in Barentsburg (78.05° N 14.12° E) in Spitsbergen archipelago, together with the data of the CUTLASS HF radars and the POLAR satellite images to study azimuthal (in the east-west direction) expansion of the high-latitude auroral arcs. It is shown that the east or west edge of the arc moved in the same direction as the convection flow, westward in the pre-midnight sector and eastward in the post-midnight sector. The velocity of arc expansion was of the order of 2.5 km/s, which is 2?3 times larger than the convection velocity measured in the arc vicinity and 2?3 times smaller than the velocity of the bright patches propagating along the arc. The arc expanded from the active auroras seen from the POLAR satellite around midnight as a region of enhanced luminosity, which might be the auroral bulge or WTS. The pole- or equatorward drift of the arcs occurred at the velocity of the order of 100 m/s that was close to the convection velocity in the same direction. These experimental results can be well explained in terms of the interchange (or flute) instability

Geomagnetic disturbances on ground associated with particle precipitation during SC

We have examined several cases of magnetosphere compression by solar wind pressure pulses using a set of instruments located in the noon sector of auroral zone. We have found that the increase in riometric absorption (sudden commencement absorption, SCA) occurred simultaneously with the beginning of negative or positive magnetic variations and broadband enhancement of magnetic activity in the frequency range above 0.1 Hz. Since magnetic variations were observed before the step-like increase of magnetic field at equatorial station (main impulse, MI), the negative declinations resembled the so-called preliminary impulse, PI. In this paper a mechanism for the generation of PI is introduced whereby PI's generation is linked to SCA – associated precipitation and the local enhancement of ionospheric conductivity leading to the reconstruction of the ionospheric current system prior to MI. Calculation showed that PI polarity depends on orientation of the background electric field and location of the observation point relative to ionospheric irregularity. For one case of direct measurements of electric field in the place where the ionospheric irregularity was present, the sign of calculated disturbance corresponded to the observed one. High-resolution measurements on IRIS facility and meridional chain of the induction magnetometers are utilized for the accurate timing of the impact of solar wind irregularity on the magnetopause

Bursts of ULF noise excited by sudden changes of solar wind dynamic pressure

International audienceWe present the results of analysis of the dayside magnetic pulsation response to a sudden change in solar wind dynamic pressure. We concentrate on the events when a burst or a series of short-lived bursts in the Pc1 frequency range with the repetition period of 7?15 min were observed on the ground around the local noon. Not every impulse of large amplitude caused this phenomenon. We have found that the ULF bursts were excited when the spectrograms of the DMSP satellites showed a signature of 10?30 keV ions in the vicinity of the magnetic flux tube of the ground observatory, that may be related to a geomagnetic storm preceding the event. In light of this finding a possible model of the phenomenon is suggested in which the hot protons influence significantly both the generation and modulation of Pc1 activity

Delayed X- and Gamma-Ray Line Emission from Solar Flare Radioactivity

We have studied the radioactive line emission expected from solar active regions after large flares, following the production of long-lived radioisotopes by nuclear interactions of flare-accelerated ions. This delayed X- and gamma-ray line emission can provide unique information on the accelerated particle composition and energy spectrum, as well as on mixing processes in the solar atmosphere. Total cross sections for the formation of the main radioisotopes by proton, 3-He and alpha-particle reactions are evaluated from available data combined with nuclear reaction theory. Thick-target radioisotope yields are provided in tabular form, which can be used to predict fluxes of all of the major delayed lines at any time after a gamma-ray flare. The brightest delayed line for days after the flare is found to be the 511 keV positron-electron annihilation line resulting from the decay of several beta+ radioisotopes. After ~2 days however, the flux of the 511 keV line can become lower than that of the 846.8 keV line from the decay of 56-Co. Our study has revealed other delayed gamma-ray lines that appear to be promising for detection, e.g. at 1434 keV from the radioactivity of both the isomer and the ground state of 52-Mn, 1332 and 1792 keV from 60-Cu, and 931.1 keV from 55-Co. The strongest delayed X-ray line is found to be the Co Kalpha at 6.92 keV, which is produced from both the decay of the isomer of 58-Co by the conversion of a K-shell electron and the decay of 57-Ni by orbital electron capture. Prospects for observation of these lines with RHESSI or future space instruments are discussed.Comment: Accepted for publication in ApJS. 29 pages, 12 figure

On the problem of preserving the health of youth in modern educational institutions of higher education

The objective of the study was to develop a set of physical exercises for students of designers whose work is associated with physical inactivity, as adverse psycho-physiological factors of the labor process. The aim of the research was an attempt to optimize the learning process of these students. The experiment involved the students of the Russian State University of Professional Education. Studied boys and girls aged from 17 to 22 years. Total surveyed 120 students. Approbation of the complex showed the effectiveness of its implementationЗадачей исследования явилась разработка комплекса физических упражнений для студентов-дизайнеров, работа которых связана с гиподинамией, как неблагоприятным психофизиологическим фактором трудового процесса. Целью исследований являлась попытка оптимизации процесса обучения указанных студентов. В эксперименте участвовали студенты Российского государственного профессионально-педагогического университета. Исследовались девушки и юноши в возрасте от 17 до 22 лет. Всего обследовано 120 студентов. Апробация комплекса показала эффективность его внедрени

Optomechanical effect in ferroelectric liquid crystal freely suspended films

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Serguei V. Yablonskii, Kazuyuki Nakano, Masanori Ozaki, Mikhail V. Kozlovsky, and Katsumi Yoshino, Journal of Applied Physics 94, 5206 (2003) and may be found at https://doi.org/10.1063/1.1611637

Dynamics of labor migration in the Republic of Belarus as a problem in the labour market

This article gives an analysis of the dynamics of the labor force in the Republic of Belarus. It covers the question of general status of migration processes in the country and focuses on its negative phenomena. The author also suggests a number of measures that can help to solve the problems in the labor market

Dynamics of labor migration in the Republic of Belarus as a problem in the labour market

This article gives an analysis of the dynamics of the labor force in the Republic of Belarus. It covers the question of general status of migration processes in the country and focuses on its negative phenomena. The author also suggests a number of measures that can help to solve the problems in the labor market

Lithium-6 from Solar Flares

By introducing a hitherto ignored Li-6 producing process, due to accelerated He-3 reactions with He-4, we show that accelerated particle interactions in solar flares produce much more Li-6 than Li-7. By normalizing our calculations to gamma-ray data we demonstrate that the Li-6 produced in solar flares, combined with photospheric Li-7, can account for the recently determined solar wind lithium isotopic ratio, obtained from measurements in lunar soil, provided that the bulk of the flare produced lithium is evacuated by the solar wind. Further research in this area could provide unique information on a variety of problems, including solar atmospheric transport and mixing, solar convection and the lithium depletion issue, and solar wind and solar particle acceleration.Comment: latex 9 pages, 2 figures, ApJ Letters in pres

Photoinduced dichroism and optical anisotropy in a liquid-crystalline azobenzene side chain polymer caused by anisotropic angular distribution of trans and cis isomers

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Lev M. Blinov, Mikhail V. Kozlovsky, Masanori Ozaki, Kent Skarp, andKatsumi Yoshino, Journal of Applied Physics 84, 3860 (1998) and may be found at https://doi.org/10.1063/1.368565