Coupled-mode analysis of two-parallel circular dielectricwaveguides using a singular perturbation technique

The evanescent coupling between two parallel circular dielectric waveguides is analyzed using a singular perturbation technique. The analysis is based on the vectorial wave formulation. The first-order coupled-mode equations are derived in an analytically closed form, which are rigorous in the sense that they satisfy the Maxwell equations and the boundary conditions for the composite waveguide system within the first-order perturbation. It is shown, in a general manner, that the two orthogonally polarized modes of the isolated waveguides yield the different coupling coefficients and the polarization effect is in proportion to the relative difference of permittivities of the core and cladding regions     

Water supplies for cities and industry

This paper discusses the two public water supply systems in Japan, for domestic and industrial use. Looking first at domestic supplies, it is found that more than 92% of the population benefited from public water services in 1982, the great majority relying on municipal systems. The proportion of demand met from surface water had reached 68% by 1982, and was set to continue rising, partly for reasons of groundwater conservation. Water quality must meet extensive legal standards. Industrial water requirements are met by a variety of systems, including municipal waterworks, recycled water and private supplies; public industrial waterworks play a relatively small part. The paper concludes by outlining the major problems of water supply that Japan must address.     

Product specificity of rice germ lipoxygenase

Incubation of linoleic acid with partially purified lipoxygenase from rice germ yielded a ratio of 9-to 13-hydroperoxides of linoleic acid of 97∶3 as measured by high performance liquid chromatography. Under similar conditions, hematin gave the 9- to 13-hydroperoxides at a ratio of 51∶49, and soybean lipoxygenase-a at 9∶91. Infrared spectral analysis revealedcis-trans configuration to predominate in the reaction products with the rice germ enzyme as was with the soybean enzyme.     

Numerical analysis of three-parallel embedded optical waveguides

Three parallel embedded dielectric waveguides are investigated numerically. The mode-matching method that matches the boundary conditions in the sense of least squares is applied to this problem, using the hybrid-modal representation. Precise numerical results for the dispersion relations and field distributions are presented for the lowest three modes near the cutoff. The frequency range in which only the three modes can propagate and the differences in their propagation constants are discussed at length, in order to highlight the available frequency range and the coupling length of the configuration with respect to its use as a directional coupler