Reliability Testing of AlGaN/GaN HEMTs Under Multiple Stressors

We performed an experiment on AlGaN/GaN HEMTs with high voltage and high power as stressors. We found that devices tested under high power generally degraded more than those tested under high voltage. In particular, the high-voltage-tested devices did not degrade significantly as suggested by some papers in the literature. The same papers in the literature also suggest that high voltages cause cracks and pits. However, the high-voltage-tested devices in this study do not exhibit cracks or pits in TEM images, while the high-power-tested devices exhibit pits

Clinical Considerations for Routine Auditory and Vestibular Monitoring in Patients with Cystic Fibrosis

Purpose Specific classes of antibiotics, such as aminoglycosides, have well-established adverse events producing permanent hearing loss, tinnitus, and balance and/or vestibular problems (i.e., ototoxicity). Although these antibiotics are frequently used to treat pseudomonas and other bacterial infections in patients with cystic fibrosis (CF), there are no formalized recommendations describing approaches to implementation of guideline adherent ototoxicity monitoring as part of CF clinical care. Method This consensus statement was developed by the International Ototoxicity Management Working Group (IOMG) Ad Hoc Committee on Aminoglycoside Antibiotics to address the clinical need for ototoxicity management in CF patients treated with known ototoxic medications. These clinical protocol considerations were created using consensus opinion from a community of international experts and available evidence specific to patients with CF, as well as published national and international guidelines on ototoxicity monitoring. Results The IOMG advocates four clinical recommendations for implementing routine and guideline adherent ototoxicity management in patients with CF. These are (a) including questions about hearing, tinnitus, and balance/vestibular problems as part of the routine CF case history for all patients; (b) utilizing timely point-of-care measures; (c) establishing a baseline and conducting posttreatment evaluations for each course of intravenous ototoxic drug treatment; and (d) repeating annual hearing and vestibular evaluations for all patients with a history of ototoxic antibiotic exposure. Conclusion Increased efforts for implementation of an ototoxicity management program in the CF care team model will improve identification of ototoxicity signs and symptoms, allow for timely therapeutic follow-up, and provide the clinician and patient an opportunity to make an informed decision about potential treatment modifications to minimize adverse events

A Study of the muon decays of B-flavored Hadrons

Thesis (Ph. D.)--University of Rochester. Dept. of Physics and Astronomy, 1981.We have conducted a search for inclusive muons in e+e- annihilations at the recently discovered T(4S) resonance using the CLEO detector at the Cornell Electron Storage Ring (CESR). The heart of the CLEO detector is a 1 m radius, 3 m long solenoidal magnet inside of which is a large cylindrical drift chamber which is used to reconstruct charged particle tracks and to measure their momenta. Muons are identified among these tracks with a system of large planar drift chambers located outside an iron absorber 2 to 3 ft thick. A detailed description of the CLEO detector is provided. An enhancement in muon production is observed at the T(4S). This is taken as confirmation that the T(4S) is above the threshold for strong decay into pairs of b-flavored hadrons (BB). The muon enhancement signals a weak decay, the hallmark of a new bare hadronic flavor. The observed muon yield leads to a branching ratio for the decay B --> Xµv of 9.4 ± 3.6% which is in reasonable agreement with predictions of the naive free quark model for B decay. No events are observed with more than one muon. This leads to a 90% confidence level upper limit for the dimuon decay B --> Xµ+µ- of 1.7%. The significance of these results within the framework of weak interaction models is discussed

Measurement of the B-Meson Inclusive Semileptonic Branching Fraction and Electron-Energy Moments

We report a new measurement of the B-meson semileptonic decay momentum spectrum that has been made with a sample of 9.4 fb −1 of e + e − data collected with the CLEO II detector at the Υ(4S) resonance. Electrons from primary semileptonic decays and secondary charm decays were separated by using charge and angular correlations in Υ(4S) events with a high-momentum lepton and an additional elec-tron. We determined the semileptonic branching fraction to be B(B → Xe + νe) = (10.91 ± 0.09 ± 0.24) % from the normalization of the electron-energy spectrum. We also measured the moments of the electron energy spectrum with minimum energies from 0.6 GeV to 1.5 GeV. i To my parents, Richard and Teresa. ii ACKNOWLEDGEMENTS There are many people who have given me invaluable help and support gettin