Gallium Nitride-based Semiconductor Optical Amplifiers

GaN-based material can potentially cover a wide spectral emission range, and laser diodes emitting in the UV, violet, blue, green, and red wavelengths have already been demonstrated and/or commercialized. GaN-based semiconductor optical amplifiers (SOAs) have the ability to boost the output power of laser diodes and thus are candidates for a broad variety of potential uses. Applications that utilize short wavelength, ultrafast pulses, including microprocessing, orthoptics, and next-generation optical storage can most benefit from GaN-based SOAs since current ultrafast pulse sources rely on large, expensive solid-state lasers. GaN-based SOAs can generate high-energy, high peak power optical pulses when used in conjunction with mode-locked laser diodes. In this chapter, the basic characteristics of these devices are discussed, concentrating on pulse amplification. Early experimental work, as well as the latest results, is presented, and improvements in the SOA design allowing the generation of higher optical pulse energy are discussed

Estudo de roteirização de veículos para distribuição de carga em Santa Catarina

TCC (graduação) - Universidade Federal de Santa Catarina. Centro Tecnológico. Engenharia Civil.O presente trabalho pretende analisar a distribuição de carga de uma empresa hipotética, com o apoio de funcionalidades específicas de um sistema de informações geográficas. Esta ferramenta foi aplicada para a resolução de um Problema de Roteirização e Programação de Veículos com Janela de Tempo (PRPVJT), que é caracterizado por possuir uma frota de veículos homogênea e clientes com demandas determinísticas. Inicialmente é feita uma revisão de literatura sobre o transporte rodoviário de cargas, sobre os grafos, que constituem o embasamento teórico do problema, sobre os sistemas de informações geográficas, que representam a ferramenta utilizada, sobre o custo do transporte rodoviário, que faz parte da solução do problema, e sobre os problemas de roteirização de veículos. Em seguida é feita a caracterização do problema, além de apresentar um procedimento para a modelagem da área de estudo e de apresentar a ferramenta utilizada. Como resultados são apresentadas as rotas otimizadas segundo o critério de menor tempo de percurso, o dimensionamento da frota de veículos e os custos operacionais de cada veículo. Após gerados, os resultados são comparados com dados de volumes médios diários das rodovias para fins de validação

Preventive effects of carvedilol on nitrate tolerance—a randomized, double-blind, placebo-controlled comparative study between carvedilol and arotinolol

AbstractObjectives. This study was designed to compare the preventive effect of nitrate tolerance between carvedilol with antioxidant properties and arotinolol without antioxidant properties.Background. The attenuation of cyclic guanosine monophosphate (cGMP) production due to inactivation of guanylate cyclase by increased superoxide has been reported as a mechanism of nitrate tolerance. Carvedilol has been known to combine alpha- and beta-blockade with antioxidant properties.Methods. To evaluate the preventive effect of nitrate tolerance, 24 patients with untreated hypertension were randomized to receive either carvedilol (10 mg twice a day [carvedilol group, n = 8]), arotinolol (10 mg twice a day [arotinolol group, n = 8]), or placebo (placebo group, n = 8). Vasodilatory response to nitroglycerin (NTG) was assessed with forearm plethysmography by measuring the change in forearm blood flow (FBF) before and 5 min after sublingual administration of 0.3 mg NTG, and at the same time blood samples were taken from veins on the opposite side to measure platelet cGMP. Plethysmography and blood sampling were obtained serially at baseline (day 0), 3 days after carvedilol, arotinolol or placebo administration (day 3) and 3 days after application of a 20 mg/24 h NTG tape concomitantly with carvedilol, arotinolol or placebo (day 6).Results. There was no significant difference in the response of FBF (%FBF) and cGMP (%cGMP) to sublingual administration of NTG on days 0 and 3 among the three groups. On day 6, %FBF and %cGMP were significantly lower in the arotinolol group and the placebo group than days 0 and 3, but these parameters in the carvedilol group were maintained.Conclusions. The results indicated that carvedilol with antioxidant properties may prevent the development of nitrate tolerance during continuous therapy with NTG compared with arotinolol without antioxidant properties