Modeling GaN Growth By Plasma Assisted MBE in the Presence of Low Mg Flux

A rate equation model is developed to investigate the plasma assisted MBE growth of GaN in the presence of a fractional monolayer of Mg. Four distinct cases were identified and modeled (i) Galimited regime (ii) Low N-limited regime (iii) Medium N-limited regime and (iv) High N-limited regime. In the model, it is assumed that Ga arriving on a Mg site undergoes faster incorporation into the epilayer through an exchange reaction compared to Ga arriving directly on a N surface. Additionally the incorporation rate of Ga was assumed to depend on the size of the Ga cluster. The results of the model are in good agreement with that of experiments. The non-monotonic behavior of growth rate with Ga flux for moderate Mg coverage is explained based on the incorporation rate dependence of Ga on the cluster size

Status of the nevada Shocker At the University of nevada, Las Vegas

The Nevada shocker is a 540 kV, 7 /spl Omega/, 50 ns pulsed power device based on Marx bank and Blumlein technologies. The Marx bank is composed of nine 60 kV capacitors charged in series with a gamma high voltage source connected by means of Ross relays in an air environment. A trigatron switch energized with an isolated mini capacitor bank is used to erect the Marx bank. The trigatron switch and erecting electrodes are contained in a gas manifold pressurized to 20 /spl plusmn/ 1 psi with dry air. The energy is released sequentially through an inductor and a water filled charging transmission line to the Blumlein immersed in deionized water. The Blumlein shapes and compresses the energy into a 50 ns pulse upon discharge. A self-breaking water switch initiates the release of energy in the Blumlein. The energy flows through a water filled discharging transmission line to the diode end of the Nevada Shocker. The current diode end of the Blumlein supports vacuum pressures as low as 6.5 /spl times/ 10/sup -6/ Torr. The chamber is pumped with the aid of a roughing pump and a cryogenic vacuum pump. The vacuum section of the Nevada Shocker is currently being rebuilt to incorporate mechanical and thermal loading capabilities with sensors located at the experiment. A number of diagnostic developments are currently underway to support flashover studies on plastics. Resistive probe and differential B-dot diagnostics with the aid of a 6 GHz 20 GS/s TDS 6604 real time scope is documented demonstrating the capability of the machine

Cannabinoid-1 receptor antagonists in type-2 diabetes.

Type-2 diabetes is closely related to abdominal obesity and is generally associated with other cardiometabolic risk factors, resulting in a risk of major cardiovascular disease. Several animal and human observations suggest that the endocannabinoid system is over-active in the presence of abdominal obesity and/or diabetes. Both central and peripheral endocannabinoid actions, via the activation of CB1 receptors, promote weight gain and associated metabolic changes. Rimonabant, the first selective CB(1) receptor blocker in clinical use, has been shown to reduce body weight, waist circumference, triglycerides, blood pressure, insulin resistance index and C-reactive protein levels, and to increase high-density lipoprotein (HDL) cholesterol and adiponectin concentrations in both non-diabetic and diabetic overweight/obese patients. In addition, a 0.5-0.7% reduction in HbA1c levels was observed in metformin- or sulphonylurea-treated patients with type-2 diabetes and in drug-naive diabetic patients. Almost half of the metabolic changes, including HbA1c reduction, could not be explained by weight loss, suggesting that there are direct peripheral effects. Rimonabant was generally well-tolerated, and the safety profile was similar in diabetic and non-diabetic patients, with a higher incidence of depressed mood disorders, nausea and dizziness. In conclusion, the potential role of rimonabant in overweight/obese patients with type-2 diabetes and at high risk of cardiovascular disease deserves much consideration