The spectral densities of nematic liquid crystals are calculated in the hydrodynamic limit with particular reference to those spectral densities that play a role in the Brillouin lines of the light scattering spectrum. It is found that the contribution of the mixed pressure-director fluctuations to the intensity of the Brillouin lines is comparable to that of the pure pressure fluctuations. Exploitation of this feature allows, in principle, the determination of the flow-director coupling

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... t from the angular dependence of the intensity of the Brillouin lines.