GaN and AlGaN have shown great potential in next-generation high-power electronic devices; however, they are plagued by a high density of interface states that affect device reliability and performance, resulting in large leakage current and current collapse. In this review, the authors summarize the current understanding of the gate leakage current and current collapse mechanisms, where awareness of the surface defects is the key to controlling and improving device performance. With this in mind, they present the current research on surface states on GaN and AlGaN and interface states on GaN and AlGaN-based heterostructures. Since GaNand AlGaN are polar materials, both are characterized by a large bound polarization charge on the order of 1013charges/cm2 that requires compensation. The key is therefore to control the compensation charge such that the electronic states do not serve as electron traps or affect device performance and reliability. Band alignment modeling and measurement can help to determine the electronic state configuration. In particular, band bending can determine how the polarization bound charge is compensated;however, the band bending is extremely sensitive to the specific processing steps such as cleaning, dielectric or metal deposition, postdeposition or postmetallization treatments, which affect oxygen coverage, carbon contamination,structural defects, bonding configurations, defect states, absorbates, and Fermi pinning states. In many cases, the specific effects of these treatments on the surface and interface states are not entirely clear as the nature of the electronic states has been obscured in complexity and subtlety. Consequently, a more systematic and methodical approach may be required.

Abstract-The role of testosterone on the development of hypertension is controversial, especially in women with polycystic ovary syndrome (PCOS) who have higher prevalence of obesity and insulin resistance than women without PCOS. Little is known about the association between serum testosterone level and blood pressure in young women with PCOS. In the 151 young Taiwanese women with PCOS enrolled in this cross-sectional study, we measured the body mass index, waist circumference, blood pressure, fasting glucose, fasting insulin, lipid profile, and hormone profiles. The free androgen index, total testosterone, and sex hormone-binding globulin, but not the level of dehydroepiandrosterone sulfate, significantly correlated with both systolic blood pressure (SBP) and diastolic blood pressure (DBP). In multiple linear regression models adjusted for age, body mass index, and other anthropometric, metabolic, and hormonal variables, the level of serum free androgen index or total testosterone, but not the sex hormone-binding globulin, were independently related to SBP and DBP. The age-and body mass index-adjusted least-square mean of serum-free androgen index levels were significantly different between the highest quartile and other quartiles of the SBP and DBP levels. The high bioavailable testosterone levels (free androgen index: Ն19%) in women with PCOS increased the risk of elevated blood pressure (SBP Ն130 mm Hg and/or DBP Ն85 mm Hg) with an odds ratio of 3.817 (Pϭ0.029; 95% CI: 1.14 to 12.74) after adjustment for age, anthropometric measures, and metabolic profiles. Our results suggest that the characteristic hyperandrogenemia in young women with PCOS was associated with an elevated SBP and DBP independent of age, insulin resistance, obesity, or dyslipidemia. Key Words: polycystic ovary syndrome Ⅲ testosterone Ⅲ systolic blood pressure Ⅲ diastolic blood pressure Ⅲ hypertension W omen with polycystic ovary syndrome (PCOS) are characterized by clinical and/or biochemical hyperandrogenism, oligomenorrhea, and the presence of polycystic ovaries. 1 PCOS is a heterogenous medical condition. Because large individual variation is present with respect to hyperandrogenism in terms of clinical manifestations and biochemistry, not all women with PCOS have elevated testosterone levels. Indeed, some women with PCOS without elevated testosterone levels may have acne, hirsutism, and/or androgenic alopecia that may arise as a result of the elevated androgens secreted by adipose tissue and the adrenal glands rather than the testosterone secreted from the ovaries.Although the increased risk of atherosclerotic cardiovascular disease and hypertension in women with PCOS remains controversial, 2,3 a variety of intriguing metabolic disturbances related to the risk for cardiovascular disease and hypertension are commonly found in a large proportion of women with PCOS, such as obesity, insulin resistance, dyslipidemia, and the metabolic syndrome. 4 Women with PCOS have been reported to have reduced vascular compliance, 5 vascular endothelial...

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Increased 14-day mortality was associated with colistin-tigecycline therapy given tigecycline minimum inhibitory concentration greater than 2 mg/L compared with colistin-carbapenem therapy for extensively drug-resistant A. baumannii bacteremia.