RESUMO
We experimentally investigate the nonlinear propagation of subnanosecond pulses in solid-core photonic bandgap fibers. By launching pulses with a few kilowatts peak power, a flat supercontinuum is generated. The long-wavelength edge of the supercontinuum can be controlled thanks to the original linear properties inherent to solid-core photonic bandgap fibers. This allows one to tailor the generated supercontinuum radiation and to keep it over a given spectral range of interest without any significant power loss.
RESUMO
Our main purpose was to evaluate the influence of cancer pain on the rewarding properties of morphine. Opioids are very addictive when used by healthy persons, conversely the occurrence of an opioid addiction seems very low when patients suffering from cancer are treated with morphine. We investigated the reinforcing properties of morphine in the place preference paradigm on a new model of mice suffering from a cancer pain induced by syngenic melanoma cells injected in the hind paw. These data were compared with mice suffering either from a short-term- or a chronic-inflammatory pain induced respectively by injection of carrageenan or complete Freund's adjuvant. Remarkably, mice suffering from cancer pain or chronic inflammatory pain did not develop any preference for the environment associated with the injection of morphine. In mice injected with melanoma cells, the specific binding of [(125)I]EYWSLAAPQRF-NH(2), an agonist of neuropeptide FF(2) receptors, was increased in several brain areas involved in the rewarding properties of opiates, including the shell of the nucleus accumbens, the major islands of Calleja, the ventral endopiriform nucleus and the amygdaloid area. Our study is the first to reveal a modification of morphine rewarding properties under cancer pain in rodents. We postulate that anti-opioid neuropeptides might contribute to the suppression of morphine rewarding effects in this murine model of cancer pain.
Assuntos
Analgésicos Opioides/farmacologia , Inflamação/complicações , Inflamação/psicologia , Morfina/farmacologia , Motivação , Neoplasias/complicações , Neoplasias/psicologia , Dor/tratamento farmacológico , Dor/psicologia , Receptores de Neuropeptídeos/efeitos dos fármacos , Animais , Autorradiografia , Comportamento Animal/efeitos dos fármacos , Doença Crônica , Condicionamento Operante/efeitos dos fármacos , Edema/patologia , Feminino , Pé/patologia , Inflamação/patologia , Camundongos , Camundongos Endogâmicos C57BL , Atividade Motora/efeitos dos fármacos , Neoplasias/patologia , Dor/etiologia , Medição da Dor/efeitos dos fármacosRESUMO
We report on a possible phase matching between two fundamental modes guided in an appropriately designed photonic crystal fiber. The phase index matching condition can be perfectly fulfilled for second or third harmonic generation and for wavelengths over a large spectral range, simply by tuning the lattice pitch. This can be achieved in such a structure thanks to the coexistence of total internal reflection and photonic bandgap guidance, leading to two different dispersive behaviours for the fundamental and the harmonic waves.
Assuntos
Desenho Assistido por Computador , Tecnologia de Fibra Óptica/instrumentação , Manufaturas , Refratometria/instrumentação , Simulação por Computador , Cristalização/métodos , Desenho de Equipamento , Análise de Falha de Equipamento , Modelos Teóricos , FótonsRESUMO
We demonstrate that our previous loss results [1] in an all-solid photonic bandgap fiber were in fact limited by bend loss. A new design, based on the addition of an extra ring of air holes on the outside of the all solid photonic bandgap structure, is then proposed, realized and characterized. We demonstrate that it significantly reduces both the fiber diameter and its sensitivity to bend loss.
RESUMO
We report the fabrication, characterization and modeling of a solid-core photonic bandgap fiber with interstitial air holes between the cladding rods. The presence of these interstitial air holes leads to a great improvement of optical properties for this kind of fiber. Particularly, we demonstrate that confinement losses and bend sensitivity are substantially reduced. Our experimental results for this new solution are well supported by numerical results.