Comparison of the calculated absorption and the measured field strength of HF waves reflected from the ionosphere

The absorption (L) of the wave in the ionosphere has been calculated. The 5.47MHz wave is transmitted from Ercis, Turkey (39.03°N, 43.37°E)and received at Elazıg, Turkey (38.70°N, 39.20°E). The field strength of this wave is measured by ITU-Compliant HF Field Strength Monitoring Terminal, and the absorption L in the ionosphere has been calculated. It is observed that the field strength of the wave is least around noon time and it increases at night times at all seasons. The diurnal and seasonal variations of the calculated absorption L shows that the maximum absorption in the wave occurs around noon time. The behaviour of the diurnal and seasonal variations of the field strength of the wave can be explained with the diurnal and seasonal variations of the calculated absorption L in the ionosphere. Equation (22) in this paper can be used to obtain the imaginary part (β) of the refractive index of the ionospheric plasma, and it can be applied to the HF radio waves propagations in the ionosphere for absorption L

Two solar eclipses observations in Turkey

In thispap er, the changesin the ionosphere over Turkey due to two solar eclipses are reported. TEC on the eclipse day (26 April 1976) and the intensity of an HF radio wave during itspropagation over 567 km between Ankara and Elazıˇg on the eclipse day (11 August 1999) exhibited a very marked decrease

The effect of earth's magnetic field on the HF radio wave modes at the heated subionosphere

In this study, the effect of the actual geometry of the magnetic field on the electron temperature has been investigated daily and seasonally for the electromagnetic wave travelling at subionosphere. The electron energy balance equation has been obtained by using the ideal gas approximation. The results show that there are notable differences between the two situations (B ? k ? z and B real, ? z). According to our theoretical study, the maximum changes are shown at L- and R-mode, small effect on X-mode and no variation on O-mode due to the real geometry of the magnetic field. Besides, the heights of the maximum points are changeable daily and seasonally for all modes at the subionosphere

The Effect of Lightning-İnduced Electromagnetic Waves on the Electron Temperatures in the Lower İonosphere

In this study, the heating of the nighttime lower ionosphere due to electromagnetic radiation in the very low frequency (VLF) band that are transmitted by cloud-to-ground (CG) lightning return strokes is investigated. For this purpose, temperature of electrons in lower ionosphere is calculated by using electron energy balance equation, which is obtained by using Maxwellian distribution. In the result of calculations, in 10 V/m of the electrical field for all modes of electromagnetic (EM) wave, it was observed that the electron temperatures increased by about 9000-11000 K at an altitude of about 85-90 km. With an increase in the electric field, it was observed that the altitude, where the maximum temperatures were reached, shifted higher. The Right-Handed mode of the EM wave, unlike other modes was not return based-state to an altitude of 95-100 km. To fully determine the effect of lightning induced electromagnetic waves on the lower ionosphere, considering the effects of polarized modes (Right and Left) can also provide more information. © 2016, University of Kuwait. All rights reserved

Long-Term Risks of Secondary Cancer for Various Whole Breast Irradiation Techniques, Including Helical IMRT

62nd Annual Meeting of the American-Society-for-Radiation-Oncology (ASTRO) -- OCT 25-28, 2020 -- ELECTR NETWORKWOS: 000582521500073[No abstract available]Amer Soc Radiat Onco

Atypical and malignant meningioma: Outcome and prognostic factors in 119 irradiated patients. A multicentre, retrospective study of the rare cancer network

14th European Cancer Conference (ECCO 14) -- SEP 23-27, 2007 -- Barcelona, SPAINWOS: 000250204000755European Canc Or

Atypical and Malignant Meningioma: Outcome and Prognostic Factors in 119 Irradiated Patients. A Multicenter, Retrospective Study of the Rare Cancer Network

PubMed ID: 18294779Purpose: To retrospectively analyze and assess the outcomes and prognostic factors in a large number of patients with atypical and malignant meningiomas. Methods and Materials: Ten academic medical centers participating in this Rare Cancer Network contributed 119 cases of patients with atypical or malignant meningiomas treated with external beam radiotherapy (EBRT) after surgery or for recurrence. Eligibility criteria were histologically proven atypical or anaplastic (malignant) meningioma (World Health Organization Grade 2 and 3) treated with fractionated EBRT after initial resection or for recurrence, and age >18 years. Sex ratio (male/female) was 1.3, and mean (±SD) age was 57.6 ± 12 years. Surgery was macroscopically complete (Simpson Grades 1-3) in 71% of patients; histology was atypical and malignant in 69% and 31%, respectively. Mean dose of EBRT was 54.6 ± 5.1 Gy (range, 40-66 Gy). Median follow-up was 4.1 years. Results: The 5- and 10-year actuarial overall survival rates were 65% and 51%, respectively, and were significantly influenced by age >60 years (p = 0.005), Karnofsky performance status (KPS) (p = 0.01), and high mitotic rate (p = 0.047) on univariate analysis. On multivariate analysis age >60 years (p = 0.001) and high mitotic rate (p = 0.02) remained significant adverse prognostic factors. The 5- and 10-year disease-free survival rates were 58% and 48%, respectively, and were significantly influenced by KPS (p = 0.04) and high mitotic rate (p = 0.003) on univariate analysis. On multivariate analysis only high mitotic rate (p = 0.003) remained a significant prognostic factor. Conclusions: In this multicenter retrospective study, age, KPS, and mitotic rate influenced outcome. Multicenter prospective studies are necessary to clarify the management and prognostic factors of such a rare disease. © 2008 Elsevier Inc. All rights reserved