High-power sampled-grating-based master oscillator power amplifier system with 23.5 nm wavelength tuning around 970 nm.

Tunable high-power diode lasers are key components in various established and emerging applications. In this work, we present a compact hybrid master oscillator power amplifier (MOPA) laser system. The system utilizes a tunable GaAs-based sampled-grating (SG) distributed Bragg reflector (DBR) laser as the master oscillator (MO), which emits around a wavelength of 970 nm in a single longitudinal mode with a spectral width below 20 pm. The SG-DBR laser consists of two SGs, each of which can be thermally tuned with microheaters. By tuning one of the two SGs, a discrete wavelength tuning of 21.1 nm can be obtained with a Vernier mode spacing of about 2.3 nm. By tuning both SGs, 23.5 nm of quasi-continuous tuning is obtained, with a mode spacing of about 115 pm. The coupling of the beam emitted by the MO into a tapered power amplifier provides an amplified output power in the watt range having a nearly diffraction-limited beam with a propagation factor of M1/e22=1.6. The combination of high power and wide wavelength tuning in a compact system makes this light source ideal for, among other things, nonlinear frequency conversion.

Mucopolysaccharidosis type IIIB (Sanfilippo B): identification of 18 novel alpha-N-acetylglucosaminidase gene mutations.

Mucopolysaccharidosis type IIIB (MPS IIIB or Sanfilippo B disease) is an autosomal recessive storage disorder caused by deficiency of the lysosomal enzyme a-N-acetylglucosaminidase. Mutation screening was performed on a group of 22 patients using a combination of SSCP/heteroduplex analysis of amplified genomic fragments and direct sequencing of cDNA fragments. Twenty-one different mutations were identified, 18 of them novel. Together they account for 82% of the disease alleles. The mutation spectrum consists of two small insertions, two small deletions, three nonsense mutations, and 14 different missense mutations, one of them (M1L) affecting the initiation codon. The vast genetic heterogeneity seen in this disorder is reflected by the fact that only three of the mutations were identified in more than one patient.

Infection Control: Incidence and etiology of nosocomial wound infection in rural African Hospital

This study was carried out in a rural community hospital in Rwanda to confirm the link between the incidence of nosocomial wound infection (NWI); medical and paramedical education; sanitary infrastructure; and material resources. A total of 126 surgical patients were evaluate over a period of eight months. Of the 126 patients examined; 65 (52) were found to have wounds contaominated by resistant nosocomial grampositive and gramnegative bacteria. Within the first 5 days of hospitalisation 70of the patients developed NWI. In all; 60(92) out of 65 patients sustained a NWI despite antibiotic treatment. The high incidence of NWI was due to inadequate medical and paramedical treatment; lack of sanitary infrastructure and insufficient material resources. It was considered that a vast improvement in hygiene procedures and methods would reduce the incidence of NWI