Broadband microwave burst produced by electron beams

Theoretical and experimental study of fast electron beams attracts a lot of attention in the astrophysics and laboratory. In the case of solar flares the problem of reliable beam detection and diagnostics is of exceptional importance. This paper explores the fact that the electron beams moving oblique to the magnetic field or along the field with some angular scatter around the beam propagation direction can generate microwave continuum bursts via gyrosynchrotron mechanism. The characteristics of the microwave bursts produced by beams differ from those in case of isotropic or loss-cone distributions, which suggests a new tool for quantitative diagnostics of the beams in the solar corona. To demonstrate the potentiality of this tool, we analyze here a radio burst occurred during an impulsive flare 1B/M6.7 on 10 March 2001 (AR 9368, N27W42). Based on detailed analysis of the spectral, temporal, and spatial relationships, we obtained firm evidence that the microwave continuum burst is produced by electron beams. For the first time we developed and applied a new forward fitting algorithm based on exact gyrosynchrotron formulae and employing both the total power and polarization measurements to solve the inverse problem of the beam diagnostics. We found that the burst is generated by a oblique beam in a region of reasonably strong magnetic field ($\sim 200-300$ G) and the burst is observed at a quasi-transverse viewing angle. We found that the life time of the emitting electrons in the radio source is relatively short, $\tau_l \approx 0.5$ s, consistent with a single reflection of the electrons from a magnetic mirror at the foot point with the stronger magnetic field. We discuss the implications of these findings for the electron acceleration in flares and for beam diagnostics.Comment: Astrophysical Journal, accepted: 26 pages, 8 figure

Gamma-Ray Polarimetry of Two X-Class Solar Flares

We have performed the first polarimetry of solar flare emission at gamma-ray energies (0.2-1 MeV). These observations were performed with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) for two large flares: the GOES X4.8-class solar flare of 2002 July 23, and the X17-class flare of 2003 October 28. We have marginal polarization detections in both flares, at levels of 21% +/- 9% and -11% +/- 5% respectively. These measurements significantly constrain the levels and directions of solar flare gamma-ray polarization, and begin to probe the underlying electron distributions.Comment: 33 pages, 12 figures, accepted for publication in Ap

Inverse Compton X-rays from relativistic flare electrons and positrons

<p><b>Context:</b> In solar flares, inverse Compton scattering (ICS) of photospheric photons might give rise to detectable hard X-ray photon fluxes from the corona where ambient densities are too low for significant bremsstrahlung or recombination. γ-ray lines and continuum in some large flares imply the presence of the necessary ~100 MeV electrons and positrons, the latter as by-products of GeV energy ions. Recent observations of coronal hard X-ray sources in particular prompt us to reconsider here the possible contribution of ICS.</p> <p><b>Aims:</b> We aim to evaluate the ICS X-ray fluxes to be expected from prescribed populations of relativistic electrons and positrons in the solar corona. The ultimate aim is to determine if ICS coronal X-ray sources might offer a new diagnostic window on relativistic electrons and ions in flares.</p> <p><b>Methods:</b> We use the complete formalism of ICS to calculate X-ray fluxes from possible populations of flare primary electrons and secondary positrons, paying attention to the incident photon angular distribution near the solar surface and thus improving on the assumption of isotropy made in previous solar discussions.</p> <p><b>Results:</b> Both primary electrons and secondary positrons produce very hard ICS X-ray spectra. The anisotropic primary radiation field results in pronounced centre-to-limb variation in predicted fluxes and spectra, with the most intense spectra, extending to the highest photon energies, expected from limb flares. Acceptable numbers of electrons or positrons could account for RHESSI coronal X/γ-ray sources.</p> <p><b>Conclusions:</b> Some coronal X-ray sources at least might be interpreted in terms of ICS by relativistic electrons or positrons, particularly when sources appear at such low ambient densities that bremsstrahlung appears implausible.</p&gt

Arctic strategies for socio-economic development of circumpolar states: national and regional aspects

In the presented paper, the authors have revealed some key priorities of the state Arctic policies of circumpolar countries on the base of the analysis of political and programmatic documents. The analysis of political and programmatic documents has shown that the state Arctic policies of the circumpolar countries are focused on expanding external interaction in the Arctic and maintaining the sustainable development of their own Arctic territorie

Understanding Human and Ecosystem Dynamics in the Kola Arctic : A Participatory Integrated Study

The Lake Imandra watershed is located in one of the most developed regions in the Arctic - the Kola Peninsula of Russia. Approximately 300 000 people live on the roughly 27 000 km² watershed, making it one of the most densely populated areas of the Arctic. Most of the people are involved in large-scale mineral extraction and processing and the infrastructure needed to support this industry. This paper reports the results of a pilot project staged for the Lake Imandra watershed that has put human dynamics within the framework of ecosystem change to integrate available information and formulate conceptual models of likely future scenarios. The observation period is one of both rapid economic growth and human expansion, with an overall economic decline in the past decade. We are applying the Participatory Integrated Assessment (PIA) approach to integrate information, identify information gaps, generate likely future scenarios, and link scientific findings to the decision-making process. We found an increasingly vulnerable human population in varying states of awareness about their local environment and fully cognizant of their economic troubles, with many determined to attempt maintenance of relatively high population densities in the near future even as many residents of northern Russia migrate south. A series of workshops have involved the citizens and local decision makers in an attempt to tap their knowledge of the region and to increase their awareness about the linkages between the socioeconomic and ecological components.Le bassin hydrographique du lac Imandra est situé dans l'une des régions les plus développées de l'Arctique, soit la presqu'île de Kola, en Russie. Près de 300 000 personnes vivent dans la zone du bassin qui couvre environ 27 000 km², ce qui en fait l'une des régions les plus peuplées de l'Arctique. La plupart des habitants travaillent dans l'extraction et le traitement miniers à grande échelle ainsi que dans l'infrastructure qui soutient cette industrie. Le présent article rapporte les résultats d'un projet pilote mis sur pied pour le bassin du lac Imandra, projet qui a placé la dynamique humaine dans le cadre du changement des écosystèmes, afin d'intégrer l'information disponible et de formuler des modèles conceptuels de scénarios probables dans l'avenir. La période d'observation en est une à la fois de croissance économique et d'expansion démographique rapides, suivie d'un déclin général au cours de la dernière décennie. On a recours à la méthode d'évaluation participative intégrée (EPI) pour intégrer l'information, y dégager des lacunes, générer des scénarios probables dans l'avenir et établir un lien entre résultats de la recherche et processus décisionnel. On a trouvé qu'il y avait une population humaine de plus en plus vulnérable qui était sensibilisée à divers degrés aux problèmes locaux de l'environnement et pleinement consciente des difficultés économiques, population dont une bonne part était fermement décidée à tenter de maintenir à brève échéance des densités de population relativement élevées, alors même que les résidents du nord de la Russie migrent en grand nombre vers le Sud. On a tenu une série d'ateliers avec citoyens et décideurs locaux pour chercher à capter leurs connaissances de la région et à accroître leur sensibilisation aux liens existant entre les composantes socio-économiques et écologiques

Analysis of robustness of homogeneous systems with time delays using Lyapunov-Krasovskii functionals

International audienceThe paper is devoted to stability analysis of homogeneous time-delay systems applying the Lyapunov-Krasovskii theory, and a generic structure of the functional is given that suits for any homogeneous system of non-zero degree (and can also be used for any dynamics admitting a homogeneous approximation). The obtained stability conditions are utilized to evaluate the domain of attraction for the delayed twisting control algorithm

Prevention of sports dental injury

The purpose of the study is to increase knowledge among athletes on the topic of first aid and prevention of acute dental injury.Цель исследования - повышение знаний среди спортсменов на тему оказания первой помощи и профилактики острой травмы зубов

Luminescent properties of Bi-doped polycrystalline KAlCl4

We observed an intensive near-infrared luminescence in Bi-doped KAlCl4 polycrystalline material. Luminescence dependence on the excitation wavelength and temperature of the sample was studied. Our experimental results allow asserting that the luminescence peaked near 1 um belongs solely to Bi+ ion which isomorphically substitutes potassium in the crystal. It was also demonstrated that Bi+ luminescence features strongly depend on the local ion surroundings

Оцінка ефективності внутрішньовенного введення лідокаїну гідрохлориду в інтраопераційному періоді

The aim of the work: to prove the fact of intravenous administration of lidocaine hydrochloride during general anesthesia to reduce the total dose of narcotic analgesics without loss of analgesic effect. Dynamic active prospective two-center study of two statistically homogeneous groups of patients was performed: in group 1 general anesthesia with fentanyl analgesia was performed, in group 2 – a combination of fentanyl and lidocaine hydrochloride. The study was performed during the anesthesiology of patients who underwent metalostesynthesis for multiple fracture with displacement of bone fragments of the upper extremity and patients undergoing laparoscopic cholecystectomy for cholelithiasis, chronic cholecystosis. It was found that the use of 1 % lidocaine hydrochloride in combination with fentanyl can significantly reduce the total dose the last one, namely the total dose of fentanyl in the group 1 was, on average, (8.63±0.72) µg/kg/h, whereas in group 2 managed to reduce the dose to (6.27±0.44) µg/kg/h to achieve adequate analgesia.Цель работы: доказать, что внутривенное введение лидокаина гидрохлорида при проведении общей анестезии позволяет уменьшить суммарную дозу наркотических анальгетиков без потери обезболивающего эффекта. Проведено динамическое активное проспективное двухцентровое исследование двух статистически однородных групп пациентов: в первой группе проводилась общая анестезия с анальгезией фентанилом, во второй – сочетание фентанила и лидокаина гидрохлорида. Исследование проводилось при анестезиологическом обеспечении больным, которым выполняли металлоостесинтез по поводу многоосколочного перелома со смещением костных отломков верхней конечности и пациентам, которым выполнялась лапароскопическая холецистэктомия по поводу желчнокаменной болезни, хронического калькулезного холецистита в стадии обострения. Было установлено, что использование 1 % лидокаина гидрохлорида в сочетании с фентанилом позволяет существенно сократить общую дозу последнего, а именно суммарная доза фентанила в первой группе составляла, в среднем (8,63 ± 0,72) мкг/кг/ч, тогда как во второй группе удалось снизить дозу до (6,27 ± 0,44) мкг/кг/ч для достижения адекватной аналгезии.Мета роботи: обґрунтувати твердження, що внутрішньовенне введення лідокаїну гідрохлориду під час проведення загальної анестезії дозволяє зменшити сумарну дозу наркотичних аналгетиків без втрати знеболювального ефекту. Проведено динамічне активне проспективне двоцентрове дослідження двох статистично однорідних груп пацієнтів: в першій групі проводилась загальна анестезія з аналгезією фентанілом, в другій – поєднання фентанілу та лідокаїну гідрохлориду. Дослідження проводилось під час анестезіологічного забезпечення хворим, яким виконували металоостеосинтез з приводу багатоуламкового перелому зі зміщенням кісткових уламків верхньої кінцівки та пацієнтам, яким виконувалась лапароскопічна холецистектомія з приводу жовчнокам’яної хвороби, хронічного калькульозного холециститу в стадії загострення. Було встановлено, що використання 1 % лідокаїну гідрохлориду в поєднанні з фентанілом дозволяє суттєво скоротити загальну дозу останнього, а саме сумарна доза фентанілу в першій групі складала, в середньому (8,63±0,72) мкг/кг/год, тоді як у другій групі вдалося зменшити дозу до 6,27±0,44 мкг/кг/год для досягнення адекватної аналгезії