[Malformation of the internal ear and recurrent meningitis: radio-surgical correlations].

Authors report one case of bilateral inner ear malformation in a 3 years-old child with congenital sensorineural hearing loss, recurrent meningitis and cerebro-spinal fluid leakage. This anomaly is a pseudo-Mondini's malformation with a meningocele through the oval window and a fistula of C.S.

[Fistula of the 4th endo-branchial pouch. Apropos of 4 cases].

The congenital fistula of the piriform sinus is a rare, often overlooked, malformation originating in the branchial pouch. More than 70 observations have been reported in the literature. The authors describe four new cases of documented fistula of the fourth endobrachial pouch.

Gratings for tunable lasers: using multidielectric coatings to improve their efficiency.

The first results of a theoretical and experimental study are presented showing that a significant enhancement of the efficiency of gratings used as wavelength selectors for cw tunable lasers may be achieved with adequate dielectric coatings. It is found that, in some cases, the energy absorbed by the grating surface can be reduced by a factor >2. The output power of a cw Rh640 dye laser was practically multiplied by the same factor.