Optical loss stability of a fiber cable under lateral force and optimum design of the coated fiber structure.
Optical loss increase characteristics under lateral force were investigated to determine the load limit for coated fiber. Plastic deformation of the coating was analyzed, and the loss increase was found to occur in the large deformation region beyond a limit theoretically determined using structural dimensions (diameter and thickness) and the material constant of the coating. The optimum coating structure for preventing loss increase has been designed by introducing the result of the lateral deformation limit as well as fiber stress induced by the lateral force and fiber strain at low temperature. The nylon outer and silicone layer diameters are 0.9 and 0.4 mm, respectively.
Nondestructive optical fiber modulation using radiation mode coupling phenomena
We demonstrate a nondestructive optical fiber modulation technology based on a radiation mode coupling (RMC) interference effect that modulates the phase difference between a guided mode and recoupled radiation modes. Because of high sensitivity of the RMC effect in the buffer layer, deep signal modulation in frequency region to the order of MHz is successfully generated by applying slight lateral deformation of a few /spl mu/m to the fiber with the piezoelectric device. Modulation index of 30 was achieved for an applied voltage of 14 V/sub pp/ and no signal fading was observed for all the states of polarization. This technique enables a free access modulation at any points along optical fibers with a wide frequency band response and low applied voltages and requires no complex composition such as polarization diversity.
Modulation of neuronal serotonin uptake by a putative endogenous ligand of imipramine recognition sites.
Imipramine inhibits the serotonin uptake by binding with high affinity to regulatory sites of this uptake located on axons that release serotonin. The number of imipramine recognition sites located on crude synaptic membrane preparations is reduced by two daily injections of imipramine or desmethylimipramine for 3 weeks. When the binding sites for [3H]imipramine are down-regulated the Vmax of the neuronal uptake of serotonin is increased. Moreover, in minces prepared from the brain hippocampus of rats receiving imipramine in a dose regimen that reduces the number of [3H]imipramine recognition sites, the efficiency of imipramine as a blocker of the serotonin uptake is diminished. Hence the high-affinity binding sites for [3H]imipramine may have a physiological role in modulation of serotonin reuptake. Probably this is mediated by an endogenous effector of these regulatory sites. A nonpeptidic constituent of rat brain capable of displacing [3H]imipramine from its high-affinity binding site and of inhibiting the serotonin uptake in a dose-related manner has been extracted and its partial purification is described.