Squares of positive (p,p)(p,p)-forms

We show that if $\alpha$ is a positive $(2,2)$-form then so is $\alpha^2$. We also prove that this is no longer true for forms of higher degree

Стилістичні характеристики англомовних заголовків інтернет видань (Stylistic characteristics of English titles of online media)

Тези присвячено визначенню стилістичних характеристик заголовку на матеріалі англомовних інтернет видань. Проаналізовано існуючі визначення поняття «англомовний заголовок», розглянуто основні функції та структурні особливості англомовних заголовків інтернет видань. (Тезисы посвящены определению стилистических характеристик заголовка на материале англоязычных интернет изданий. Проанализовано существующие определения понятия «англоязычный заголовок», рассмотрены основные функции и структурные особенности англоязычных заголовков интернет изданий.) (The research is devoted to the stylistic characteristics of the title based on English-language INTERNET editions. Analyzed the existing definition of «English title», the basic functions and structural features of the English-language headlines.

Carrier lifetimes in green emitting InGaN/GaN disks‐in‐nanowire and characteristics of green light emitting diodes

Improvement in the internal quantum efficiency (IQE) of InGaN/GaN disks‐in‐nanowires by surface passivation is demonstrated. The highest IQE achieved through surface passivation for green emitting (λ=540 nm) InGaN/GaN disks‐in‐nanowires is ∼53%. Radiative and nonradiative carrier lifetimes are calculated for as‐grown and surface passivated green emitting disks‐in‐nanowires. Passivated green sample exhibits a room temperature radiative lifetime of ∼748 ps, which is much smaller than that of equivalent quantum wells. Electroluminescence measurements on passivated green light emitting diodes containing InGaN disks demonstrate no roll over or efficiency droop up to 375 A/cm 2 , and exhibit a blue‐shift of 7 nm in peak wavelength. An enhancement in the light output due to surface passivation is observable in the relative external quantum efficiency of the surface passivated devices as compared with the as‐grown samples. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98222/1/812_ftp.pd

Role of bias conditions in the hot carrier degradation of AlGaN/GaN high electron mobility transistors

The impacts of gate bias and device temperature on carrier energy distributions are reported for AlGaN/GaN High Electron Mobility Transistors. The lateral electric field and the average carrier energy are the highest at the end of gate on the gate‐drain access side. The number of high energy carriers is the greatest in the semi‐ON operating condition, with maximum energies exceeding the activation energy of defects in the AlGaN. There is a significant decrease in the number of very high energy carriers (greater than 2 eV) as the device temperature increases whereas the number of moderately energetic carriers (between 1 to 2 eV) is higher at elevated temperatures.(© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98280/1/794_ftp.pd