19 research outputs found
Association of upper gastrointestinal symptoms with gastroduodenal ulcers in endoscopic trials of arthritis patients treated with naproxen, celecoxib or placebo
An endoscopic study of the gastroduodenal effects of SC-69124A, a parenteral COX-2-specific inhibitor, in the elderly
Serial endoscopies at one month intervals demonstrate a lower incidence of gastroduodenal ulcers with celecoxib compared to naproxen
High speed analog-to-digital conversion with silicon photonics
Sampling rates of high-performance electronic analog-to-digital converters (ADC) are fundamentally limited by the timing jitter of the electronic clock. This limit is overcome in photonic ADC's by taking advantage of the ultra-low timing jitter of femtosecond lasers. We have developed designs and strategies for a photonic ADC that is capable of 40 GSa/s at a resolution of 8 bits. This system requires a femtosecond laser with a repetition rate of 2 GHz and timing jitter less than 20 fs. In addition to a femtosecond laser this system calls for the integration of a number of photonic components including: a broadband modulator, optical filter banks, and photodetectors. Using silicon-on-insulator (SOI) as the platform we have fabricated these individual components. The silicon optical modulator is based on a Mach-Zehnder interferometer architecture and achieves a V[subscript pi]L of 2 Vcm. The filter banks comprise 40 second-order microring-resonator filters with a channel spacing of 80 GHz. For the photodetectors we are exploring ion-bombarded silicon waveguide detectors and germanium films epitaxially grown on silicon utilizing a process that minimizes the defect density.Defense Advanced Research Projects Agency (contracts W911NF-04-1-0431 and HR0011-05-C-0155)Department of the Air Force (Air Force Contract FA8721-05-C-0002