Quasi-phase-matched generation of optical intensity waves.

The evolution of modulated light in a nonlinear medium, when described in terms of intensity waves, depends critically on a phase-matching condition for the intensity waves. We formally develop the conditions for quasi-phase matching of the interacting intensity waves and show that a periodic nonlinearity can be utilized to eliminate the dephasing between them. This is verified using stimulated Brillouin scattering with a periodically nonlinear optical fiber that has a period length equal to one-half of the (modulation) wavelength of the intensity waves.

Increased patient comfort utilizing botulinum toxin type a reconstituted with preserved versus nonpreserved saline.

Purpose: To demonstrate that injection of botulinum toxin type A is less painful when mixed with preserved saline compared with the suggested preservative-free saline reconstitution.

Methods: Two different injections were compared on 20 patients who had prior botulinum toxin type A treatments. Each side was injected with toxin reconstituted with either preserved or nonpreserved (0.