High-field electron transport in doped ZnO

Current-voltage characteristics have been measured for ZnO:Ga and Zn:Sb epitaxial layers with electron densities ranging from 1.4x10(17) cm(-3) to 1.1 x 10(20) cm(-3). Two-terminal samples with coplanar electrodes demonstrate virtually ohmic behavior until thermal effects come into play. Soft damage of the samples takes place at high currents. The threshold power (per electron) for the damage is nearly inversely proportional to the electron density over a wide range of electron densities. Pulsed voltage is applied in order to minimize the thermal effects, and thus an average electric field of 150 kV cm(-1) is reached in some samples subjected to 2 ns voltage pulses. The results are treated in terms of electron drift velocity estimated from the data on current and electron density under the assumption of uniform electric field. The highest velocity of similar to 1.5 x 10(7) cm s(-1) is found at an electric field of similar to 100 kV cm(-1) for the sample with an electron density of 1.4 x 10(17) cm(-3). The nonohmic behavior due to hot-electron effects is weak, and the dependence of the electron drift velocity on the doping resembles the variation of mobility

Hot Phonons in a Biased Two-Dimensional InGaAs Channel

Experimental dependence of microwave noise temperature on supplied electric power is used to estimate hot-phonon number in a modulation-doped In_{0.52}Al_{0.48}As/In_{0.53}Ga_{0.47}As/In_{0.7} Ga_{0.3}As/In_{0.52}Al_{0.48}As two-dimensional electron gas channel (n_{2D}=2.3×10^{12} cm^{-2}). The nonequilibrium occupancy of the involved longitudinal optical phonon states exceeds the equilibrium one nearly twice at 2 kV/cm electric field. tes

AntimÜllerian hormone as indicator of ovarian dysfunction

Aim. The purpose of this study was to examine various hormonal, biochemical and environmental factors (i.e., smoking and alcohol intake) and to investigate their possible correlation to the development of polycystic ovary syndrome (PCOS). The main objective was to evaluate the associations between hormonal profile and the antimüllerian hormone (AMH) levels in PCOS patients and their relation to environmental factors. Patients and Methods. In two gynecological clinics, 38 women with PCOS (defined according to the Rotterdam criteria) were enrolled and observed in relation to AMH, follicle stimulating hormone (FSH), luteinizing hormone (LH), testosterone (T), Δ4-androstendione (Δ4-A), dehydroepiandrosterone sulfate (DHEA-S) and glucose plasma concentrations. Obesity, smoking and alcohol exposure were also studied. Results. AMH, T, Δ4-Α, DHEA-S, LH and FSH were increased in 76.3%, 50%, 31.8%, 23.7%, 21% and 18.4% of the patients, respectively. The LH/FSH ratio and glucose concentrations increased abnormally in 18.4% and 15.8% of the patients, respectively. AMH and T levels were both increased in 47.4% of the patients whereas both AMH and LH levels increased in 21% of the patients. Smoking, alcohol intake, obesity and glucose concentrations were not associated with AMH concentrations. On the contrary, high levels of T and LH were linked to higher levels of AMH. FSH concentrations were not increased in these patients. Conclusion. AMH is an important hormonal parameter for the diagnosis of PCOS. Larger clinical controlled studies are necessary in an effort to further investigate the inclusion of AMH measurement in the diagnostic criteria of PCOS. © 2017, Acta Endocrinologica Foundation. All rights reserved

Low-Grade Uterine Epithelioid Hemangioendothelioma Presented as a Submucosal Leiomyoma during Labor

With the exception of leiomyomas, soft tissue tumors of the uterine corpus are not common. This is particularly true for vascular neoplasms, with the epithelioid hemangioendothelioma being a curiosity; not more than twenty-two cases of malignant hemangioendotheliomas have been reported in the literature so far, all of which were high-grade hemangioendotheliomas (hemangiosarcomas). We present herewith a unique case of low-grade epithelioid hemangioendothelioma of the uterus in a pregnant woman aged 29 years. The clinical, histological, and immunohistochemical characteristics of this entity, together with its differential diagnosis, are discussed