Association of temporal factors and suicides in the United States, 2000–2004

The purpose of the study was to examine the association of temporal factors, in particular days of the week and seasons of the year and death from suicide in the United States. Data were pooled from the Multiple Cause of Death Files. Hierarchical logistic regression models were fitted to all deaths occurring in 2000 through 2004 by suicide. The incidence of suicide was significantly higher on Wednesdays, compared to Sunday. Specifically, individuals were 99% more likely to kill themselves on Wednesday than on Sunday. Suicides were more prevalent in the summer months, and they were less likely to occur in winter. The state suicide rate significantly elevated individual suicide risk. The results held even after controlling for the potentially confounding effects of socio-economic and demographic variables at both the individual and state levels. It was concluded that the observed association between seasonality and suicide cannot be discounted as a mere coincidence. Future research ought to focus on integrating individual level data and contextual variables when testing for seasonality effects

AlGaN/GaN HFET’S

The strong spontaneous and piezoelectric polarizations in pseudomorphic AlGaN/GaN on SiC substrates are used to induce 2DEG sheet density of > 1 x 10 13 /cm 2 with mobility up to 1,700 cm 2 /vs. The processing sequence and HEMT electrode layout are presented. The output power and power-added efficiency in the 8-10 GHz frequency range are shown for CW bias conditions and optimum tuning in class B operation. Single-gate, center-fed 100 µm periphery devices gave 11.2 W/mm at 32% power-added efficiency; two-gate, 200 µm periphery devices with 50 µm pitch gave 8.7 W/mm at 48% power-added efficiency, and 12-gate, 1.5 mm periphery devices with 50 µm pitch gave 6.7 W/mm at 42% power-added efficiency. For comparison, the latter gave 9.4 W/mm at 43% power-added efficiency in low duty cycle pulsed operation . The key limitation for CW power performance is self-heating, which raises the knee voltage by (T/300) 1.8 for T channel temperature in °K