Optical and Ionospheric Phenomena at EISCAT under continuous X-mode HF pumping

We present experimental results from multiinstrument observations in the high-latitude ionospheric F2 layer at the EISCAT (European Incoherent Scatter Scientific Association) heating facility. The results come from a set of experiments, when an X-polarized HF pump wave at high heater frequencies (fH > 6.0 MHz) was injected into the F region of the ionosphere toward the magnetic zenith. Experiments were carried out under quiet magnetic conditions with an effective radiated power of 458–548 MW. HF pumping was produced at different heater frequencies, away from electron gyroharmonic frequencies, and different durations of heater pulses. We show the first experimental evidence of the excitation of artificial optical emissions at red (630 nm) and green (557.7 nm) lines in the high-latitude ionospheric F2 layer induced by an X-polarized HF pump wave. Intensities at red and green lines varied in the range 110–950 R and 50–350 R, respectively, with a ratio of green to red line of 0.35–0.5. The results of optical observations are compared with behaviors of the HF-enhanced ion and plasma lines from EISCAT UHF incoherent scatter radar data and small-scale field-aligned artificial irregularities from Cooperative UK Twin Located Auroral Sounding System observations. It was found that the X-mode radio-induced optical emissions coexisted with HF-enhanced ion and plasma lines and strong artificial field-aligned irregularities throughout the whole heater pulse. It is indicative that parametric decay or oscillating two-stream instabilities were not quenched by fully established small-scale field-aligned artificial irregularities excited by an X-mode HF pump wave

Disturbances of electron density in the high latitude upper (F-region) ionosphere induced by X-mode HF pump waves from EISCAT UHF radar observations

The paper presents experimental results concerning disturbances of electron density in the high latitude ionosphere F-region, induced by powerfulHF radio waves (pump waves) with extraordinary (X-mode) polarization. The experiments were carried out at the EISCAT/Heating facility at Tromsø, Norway. The EISCAT UHF incoherent scatter radar (ISR), running at 930 MHz, co-located with a heating facility, was used to detect the disturbances of electron density. In the course of the experiments, the X-mode HF pump waves radiated into the F-region towards the magnetic zenith at different pump frequencies and ratios of the pump frequency to the critical frequency of the F2 layer.The effective radiated power was ERP = 360–820 MW. An increase in electron densities was found in a wide altitude range, giving rise to field-aligned ducts with enhanced electron density. The features and behavior of the ducts were investigated. It was revealed that the ducts are formed under quiet background geophysical conditions in a wide altitude range up to the upper altitude limit of EISCAT ISR measurements, when the pump frequencies were both below and above the critical frequency of the F2 layer (fH ≤ foF2 or fH > foF2). A plausible formation mechanism of the ducts is discussed.Представлены результаты экспериментальных исследований возмущений электронной концентрацииNe в высокоширотной F-области ионосферы, вызванные воздействием мощных КВ-радиоволн необыкновенной (Х-мода) поляризации. Эксперименты выполнялись на КВ нагревном стенде EISCAT/ Heating в г. Тромсё, Норвегия при эффективной мощности излучения 360–820 МВт. В качестве средства диагностики возмущений Ne использовался EISCAT радар некогерентного рассеяния радиоволн (НР) на частоте 930 МГц, пространственно совмещенный с КВ нагревным стендом. Обнаружено возрастание Ne в широком диапазоне высот, которое формирует каналы повышенной электронной плотности, вытянутые вдоль магнитного поля Земли. Исследованы характеристики и условия создания каналов. Обсуждается возможный механизм формирования каналов Ne при Х-нагреве высокоширотной F-области ионосферы

Phenomena induced by powerful HF pumping towards magnetic zenith with a frequency near the F-region critical frequency and the third electron gyro harmonic frequency

Multi-instrument observational data from an experiment on 13 October 2006 at the EISCAT/HEATING facility at Tromsø, Norway are analysed. The experiment was carried out in the evening hours when the electron density in the F-region dropped, and the HF pump frequency <I>f<sub>H</sub></I> was near and then above the critical frequency of the F2 layer. The distinctive feature of this experiment is that the pump frequency was just below the third electron gyro harmonic frequency, while both the HF pump beam and UHF radar beam were directed towards the magnetic zenith (MZ). The HF pump-induced phenomena were diagnosed with several instruments: the bi-static HF radio scatter on the London-Tromsø-St. Petersburg path, the CUTLASS radar in Hankasalmi (Finland), the European Incoherent Scatter (EISCAT) UHF radar at Tromsø and the Tromsø ionosonde (dynasonde). The results show thermal electron excitation of the HF-induced striations seen simultaneously from HF bi-static scatter and CUTLASS radar observations, accompanied by increases of electron temperature when the heater frequency was near and then above the critical frequency of the F2 layer by up to 0.4 MHz. An increase of the electron density up to 25% accompanied by strong HF-induced electron heating was observed, only when the heater frequency was near the critical frequency and just below the third electron gyro harmonic frequency. It is concluded that the combined effect of upper hybrid resonance and gyro resonance at the same altitude gives rise to strong electron heating, the excitation of striations, HF ray trapping and extension of HF waves to altitudes where they can excite Langmuir turbulence and fluxes of electrons accelerated to energies that produce ionization

Diagnostic Criteria for Macular Edema Associated with Venous Occlusions

Background. Macular edema is considered as a risk factor for a significant decrease in the visual acuity and quality of life of the patient, regardless of its cause. The search for the causes of macular edema in some cases should include an interdisciplinary approach and laboratory studies to correctly determine its etiology and management tactics for such patients. Therefore, the differentiation of the etiology and pathogenesis of macular edema at the stage of diagnosis determines the possibility of preserving not only visual functions, but in some cases the patient's life.Aim: to present clinical cases of macular edema associated with central retinal vein thrombosis of various etiologies. Materials and methods. A prospective study of individual patients with macular edema associated with thrombosis of central retinal vein or its branches was conducted in real clinical practice. All patients underwent a standard ophthalmological examination, as well as optical coherence tomography, and a patient with suspected macroglobulinemia underwent a biochemical blood test.Results. In the first clinical case, macular edema was associated with an exudative form of retinal arterial macroaneurysm. The patient underwent direct laser coagulation of retinal arterial macroaneurysm. 6 months after direct laser coagulation of macroaneurysm, the best corrected visual acuity of the left eye was 1.0. The fundus - macroaneurysm, retinal edema, solid exudates are not ophthalmoscopic. In the second clinical case, macular edema, thrombosis of central retinal vein is associated with Waldenstrom disease. Follow-up and treatment of the underlying disease by a hematologist were recommended.Conclusion. Thus, macular edema proceeding against the background of central retinal vein thrombosis and its branches, having atypical symptoms in the form of ring-shaped deposition of hard exudates, exudative retinal detachment, the presence of a bilateral process, as well as resistance to anti-VEGF therapy require a careful collection of the patient's medical history and the presence of other ophthalmic vascular pathology

FEATURES OF GENOTYPiNG VARIABILITY OF STRAINS OF BORDETELLA PERTUSSIS ALLOCATED FROM PATIENTS WITH WHOOPING COUGH IN RUSSIA

On the basis of studying of features of structure of 7 genes determining major factors of pathogenicity of the causative agent of whooping cough - ptxA, ptxB, ptxC, ptxD, ptxE, ptxP and prn, features of genotyping variability of strains of B.pertussis allocated from patients with whooping cough in Russia are shown. Dynamics of formation of population of strains of the causative agent of whooping cough is tracked and is established that population of strains of B.pertussis is formed by clonal expansion of strains with, new genetic structure of major factors of pathogenicity - pertussis toxin and. pertactin. The structure of population of strains of B.pertussis causing a disease by whooping cough, at the present stage of epidemic process of a pertussis infection - domination. of strains with new «non-vaccine» alleles genes - ptxA1 (97,7 %), ptxC2 (87,4 %), prn2 (89,5 %) and. ptxP3 (93,3 %), in 2,2 % cases with ptxB2 allele and. in 1,3 % cases with. prn9 allele circulate

MODERN STATUS OF VACCINE PROPHYLAXIS OF MUMPS

Abstract. Vaccination against mumps is conducted in Russian Federation since 1981. This made it possible to decrease mumps incidence more than 600 times in compare with pre-vaccination period. Moreover disease became milder and mortality was eliminated. Population of Russia is immunized by locally-produced mono- and bivalent vaccines on the base of L3 strain. Vaccination and revaccination against mumps is safe and highly effective

The impact of visual functions on athletes’ results and methods of their improvements

Regardless of the sport, maintaining and improvement of visual functions in athletes act an important role in achieving personal records.In this article, the interrelationships between sports results and the state of visual functions were determined, as well as devices and methods were analyzed, thanks to which it is possible to improve functions of the visual analyzer

Spectroscopic determination of hole density in the ferromagnetic semiconductor Ga1−x_{1-x}Mnx_{x}As

The measurement of the hole density in the ferromagnetic semiconductor Ga$_{1-x}$Mn$_{x}$As is notoriously difficult using standard transport techniques due to the dominance of the anomalous Hall effect. Here, we report the first spectroscopic measurement of the hole density in four Ga$_{1-x}$Mn$_{x}$As samples ($x=0, 0.038, 0.061, 0.083$) at room temperature using Raman scattering intensity analysis of the coupled plasmon-LO-phonon mode and the unscreened LO phonon. The unscreened LO phonon frequency linearly decreases as the Mn concentration increases up to 8.3%. The hole density determined from the Raman scattering shows a monotonic increase with increasing $x$ for $x\leq0.083$, exhibiting a direct correlation to the observed $T_c$. The optical technique reported here provides an unambiguous means of determining the hole density in this important new class of ``spintronic'' semiconductor materials.Comment: two-column format 5 pages, 4 figures, to appear in Physical Review