179 research outputs found
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 ( 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, 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
Regularized energy-dependent solar flare hard x-ray spectral index
The deduction from solar flare X-ray photon spectroscopic data of the energy
dependent model-independent spectral index is considered as an inverse problem.
Using the well developed regularization approach we analyze the energy
dependency of spectral index for a high resolution energy spectrum provided by
Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The regularization
technique produces much smoother derivatives while avoiding additional errors
typical of finite differences. It is shown that observations imply a spectral
index varying significantly with energy, in a way that also varies with time as
the flare progresses. The implications of these findings are discussed in the
solar flare context.Comment: 13 pages; 5 figures, Solar Physics in pres
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
Prototype ATLAS IBL Modules using the FE-I4A Front-End Readout Chip
The ATLAS Collaboration will upgrade its semiconductor pixel tracking
detector with a new Insertable B-layer (IBL) between the existing pixel
detector and the vacuum pipe of the Large Hadron Collider. The extreme
operating conditions at this location have necessitated the development of new
radiation hard pixel sensor technologies and a new front-end readout chip,
called the FE-I4. Planar pixel sensors and 3D pixel sensors have been
investigated to equip this new pixel layer, and prototype modules using the
FE-I4A have been fabricated and characterized using 120 GeV pions at the CERN
SPS and 4 GeV positrons at DESY, before and after module irradiation. Beam test
results are presented, including charge collection efficiency, tracking
efficiency and charge sharing.Comment: 45 pages, 30 figures, submitted to JINS
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
Feasibility studies for the measurement of time-like proton electromagnetic form factors from p¯ p→ μ+μ- at P ¯ ANDA at FAIR
This paper reports on Monte Carlo simulation results for future measurements of the moduli of time-like proton electromagnetic form factors, | GE| and | GM| , using the p¯ p→ μ+μ- reaction at P ¯ ANDA (FAIR). The electromagnetic form factors are fundamental quantities parameterizing the electric and magnetic structure of hadrons. This work estimates the statistical and total accuracy with which the form factors can be measured at P ¯ ANDA , using an analysis of simulated data within the PandaRoot software framework. The most crucial background channel is p¯ p→ π+π-, due to the very similar behavior of muons and pions in the detector. The suppression factors are evaluated for this and all other relevant background channels at different values of antiproton beam momentum. The signal/background separation is based on a multivariate analysis, using the Boosted Decision Trees method. An expected background subtraction is included in this study, based on realistic angular distributions of the background contribution. Systematic uncertainties are considered and the relative total uncertainties of the form factor measurements are presented
HIV-1 Vpr Triggers Mitochondrial Destruction by Impairing Mfn2-Mediated ER-Mitochondria Interaction
Human immunodeficiency virus 1 (HIV-1) viral protein R (Vpr) has been shown to induce host cell death by increasing the permeability of mitochondrial outer membrane (MOM). The mechanism underlying the damage to the mitochondria by Vpr, however, is not clearly illustrated. In this study, Vpr that is introduced, via transient transfection or lentivirus infection, into the human embryonic kidney cell line HEK293, human CD4+ T lymphoblast cell line SupT1, or human primary CD4+ T cells serves as the model system to study the molecular mechanism of Vpr-mediated HIV-1 pathogenesis. The results show that Vpr injures MOM and causes a loss in membrane potential (MMP) by posttranscriptionally reducing the expression of mitofusin 2 (Mfn2) via VprBP-DDB1-CUL4A ubiquitin ligase complex, gradually weakening MOM, and increasing mitochondrial deformation. Vpr also markedly decreases cytoplasmic levels of dynamin-related protein 1 (DRP1) and increases bulging in mitochondria-associated membranes (MAM), the specific regions of endoplasmic reticulum (ER) which form physical contacts with the mitochondria. Overexpression of Mfn2 and DRP1 significantly decreased the loss of MMP and apoptotic cell death caused by Vpr. Furthermore, by employing time-lapse confocal fluorescence microscopy, we identify the transport of Vpr protein from the ER, via MAM to the mitochondria. Taken together, our results suggest that Vpr-mediated cellular damage may occur on an alternative protein transport pathway from the ER, via MAM to the mitochondria, which are modulated by Mfn2 and DRP1
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