No abstract

Resistance to macrolides among group A streptococci is an increasing problem worldwide. We examined 496 strains phenotypically and genotypically for resistance to erythromycin and clindamycin. Strains were isolated in five different geographical areas representing about 45% of the total Quebec population. The overall resistance rate was 4.6% but varied from 0% in rural areas to 9.4% in Montreal. Of the 23 strains showing resistance to erythromycin, 15 (65%) had an identical pulsed-field gel electrophoresis pattern, were of serotype M28T28 and harboured the erm(TR) gene, suggesting the spread of a single clone. Of the remaining eight strains, two strains had the erm(B) gene, five had the mef gene and one with a different serotype also had the erm(TR) gene.

Lead lanthanum zirconate titanate (PLZT) thin films were deposited on r-plane sapphire at low temperatures by RF triode magnetron sputtering using lead compensated hot-pressed targets. To obtain fully perovskite phase in the films, two types of post-deposition processing were investigated: rapid thermal annealing (RTA) and furnace annealing (FA). Dielectric and electro-optic properties of PLZT films were found to be strongly dependent on annealing conditions. The peak dielectric constant of the films were 1200 and 2800 with Curie temperatures of 110 degrees C and 190 degrees C after RTA and FA processing, respectively. The dielectric losses in the films were fairly low; tan deltas were less than 0.02 after RTA and less than 0.04 after FA processing. The films showed good optical transmission characteristics after annealing and an anomalously large effective quadratic electro-optic effect was observed in one furnace annealed film.

We present theoretical and experimental results of a novel fiber-optic wavelength-division multiplexing (WDM) design employing a broadband (>150-nm) dichromated gelatin volume holographic grating operating in a reflective Littrow configuration with on-axis optics, a single lens, and one fiber array. This configuration can achieve better than -1.5-dB insertion loss and -40-dB cross talk for a 6-channel system and -2.5-dB insertion loss and -20-dB cross talk for a 12-channel system with 15-nm channel spacing. For an experimental 4-channel WDM unit we measured better than -1.5-dB insertion loss for all channels and less than -32-dB cross talk. This design can provide cost and performance benefits for local area network communication applications.

No abstract