High power, 60 W quasi-CW, visible laser diode arrays

Visible spectrum diode arrays have been fabricated from (Al/sub x/Ga/sub 1-x/)/sub 0.5/In/sub 0.5/P-Ga/sub 0.4/In/sub 0.6/P quantum well heterostructures operating to high output powers at wavelengths of approximately 690 nm. Bars 7.5 mm long with 110 mu m broad area emitting apertures on 125 mu m centers have reached quasi-CW output powers of 60 W.<>     

Vanadium distribution in melts intermediate to ferroalloy production from vanadiferous slag

Processing of vanadiferous slags through the pyrometallurgical process route appears to offer advantages both in terms of ferroalloy production and in the potential for efficient vanadium recovery from hot metal. In order to investigate the effect of slag composition on the phase distribution of vanadium, a series of laboratory smelting experiments was carried out. The effect of basicity adjustments on the slag/metal distribution of iron, vanadium, and manganese was investigated using carbon and FeSi as a reductant. A simulation of the final stage of slag reduction was also carried out to determine the efficiency of vanadium recovery during metallothermic smelting using aluminum and FeSi. Formerly with Industrial Research Ltd., Wellington, New Zealand     

Coherent lasers turn up the power

Three categories of multiwatt, coherent laser designs are discussed. The designs are single-mode waveguides suitable for output powers in the order of 200 mW, single-mode operation of multimode lasers, which are suitable for operation between 0.5 and 1.0 W, and the monolithically integrated master-oscillator power amplifier (M-MOPA) designs that have demonstrated 4.5 W of spectrally coherent output power and more than 0.8 W of single-lobe diffraction-limited output power in a technology that is scalable to even higher output powers. Laser-diode design architectures and the unique properties of semiconductor materials are reviewed     

An outbreak of multidrug-resistant pneumococcal pneumonia and bacteremia among unvaccinated nursing home residents

BACKGROUND: Outbreaks of pneumococcal disease are uncommon and have occurred mainly in institutional settings. Epidemic, invasive, drug-resistant pneumococcal disease has not been seen among adults in the United States. In February 1996, there was an outbreak of multidrug-resistant pneumococcal pneumonia among the residents of a nursing home in rural Oklahoma. METHODS: We obtained nasopharyngeal swabs for culture from residents and employees. Streptococcus pneumoniae isolates were serotyped and compared by pulsed-field gel electrophoresis. A retrospective cohort study was conducted to identify factors associated with colonization and disease. RESULTS: Pneumonia developed in 11 of 84 residents (13 percent), 3 of whom died. Multidrug-resistant S. pneumoniae, serotype 23F, was isolated from blood and sputum from 7 of the 11 residents with pneumonia (64 percent) and from nasopharygeal specimens from 17 of the 74 residents tested (23 percent) and 2 of the 69 employees tested (3 percent). All the serotype 23F isolates were identical according to pulsed-field gel electrophoresis. Recent use of antibiotics was associated with both colonization (relative risk, 2.3; 95 percent confidence interval, 1.3 to 4.2) and disease (relative risk, 3.6; 95 percent confidence interval, 1.2 to 10.8). Only three residents (4 percent) had undergone pneumococcal vaccination. After residents received pneumococcal vaccine and prophylactic antibiotics, there were no additional cases of pneumonia, and the rates of carriage decreased substantially. CONCLUSIONS: In this outbreak a single pneumococcal strain was disseminated among the residents and employees of a nursing home. The high prevalence of colonization with a virulent organism in an unvaccinated population contributed to the high attack rate. Clusters of pneumococcal disease may be underrecognized in nursing homes, and wider use of pneumococcal vaccine is important to prevent institutional outbreaks of drug-resistant S. pneumoniae infection.     

Pretreatment with intralesional hyaluronidase prior to excision of dermatofibrosarcoma protuberans

A DNA fragment from Pseudomonas fluorescens DSM50106 containing the genes for the uptake and utilization of mannitol, arabitol and glucitol was cloned in Escherichia coli and sequenced. Seven open reading frames (mtlEFGKDYZ) were identified on the 10031 bp fragment. The deduced amino acid sequences of the first four open reading frames (mtlEFGK) revealed significant similarity to the components of the maltose transport system in E. coli and Salmonella typhimurium. The gene mtlD encoding a polyol dehydrogenase was located downstream of mtlK. The deduced proteins of the last two genes on the fragment showed a high similarity to a fructokinase from Vibrio alginolyticus (MtlZ) and a xylulose kinase from Streptomyces rubiginosus (MtlY), respectively. Both genes were expressed in E. coli. MtlZ phosphorylated fructose, glucose and glucitol whereas MtlY was highly specific for xylulose. Upstream of mtlE, a putative promoter/operator region was identified by promoter probe studies which was active in P. fluorescens but not in E. coli.     

The Peter Landin prize

The Peter Landin prize honours the best paper presented at each year’s International Symposium on the Implementation and Application of Functional Languages (IFL). It has been awarded every year since 2003, and covers a range of topics including functional operating systems, static analysis for cost information of functional programs, techniques to improve array processing for data locality and parallelism, explicit parallel coordination, supercompilation, and a rational deconstruction of Landin’s SECD machine itself. This article describes the history of the prize, explains why Peter Landin was chosen as nominee, and describes each of the articles that have been awarded the prize to date.     

Spatial distribution of odors in simulated benthic boundary layer flows

Many animals orient to odor sources in aquatic habitats where different flows and substrates affect the hydrodynamics of benthic boundary layers. Since the dispersal of chemicals is due to the fluid mechanics of a particular environment, we quantified the changes in the fine structure of an odor plume under different hydrodynamic conditions in the benthic boundary layer of a laboratory flume. We sampled turbulent odor plumes at 10 Hz using a microchemical sensor (150 µm diameter) under two flow speeds: 3.8 and 14.4 cm/sec, and at 1, 8, 50 mm above the substrate. These distances above the substrate occur within different flow regions of the boundary layer and correlate with the location of crustacean chemosensory appendages within boundary layer flows. The high flow velocity exhibited a greater level of turbulence and had more discrete odor pulses than the low flow velocity. In general, odor signals showed a high level of temporal variation in fast flow at heights 1 and 8 mm above the substrate. In slow flow, temporal variation was maximal at 50 mm above the substrate, exhibiting more variance than the same height at the fast flow. These patterns of odor signals resulted in part from differences in the height above the substrate of the main axis of the odor plume at the two flow speeds. Our results imply that animals chemically orienting to an odor source will need to compensate for varying hydrodynamic properties of odor transport and dispersal. The method by which animals extract spatial information from odor plumes will need to account for changing flow conditions, or else it will not be equally efficient in extracting information about chemical spatial distributions.     

Large System Performance of SPEC OMP Benchmark Suites

Performance characteristics of application programs on large-scale systems are often significantly different from those on smaller systems. SPEC OMP includes benchmark suites intended for measuring performance of modern shared memory parallel systems. SPEC OMPM2001 is developed for medium-scale (4- to 16-way) systems whereas SPEC OMPL2001 is developed for large-scale systems (32-way and larger). We present our experiences on benchmark development in achieving good scalability using the OpenMP API. We also analyze the published results of these benchmark suites on large systems (32-way and larger), based on application program behavior and systems' architectural features.     

Fabrication of Textured Silicon Carbide via Seeded Anisotropic Grain Growth

Highly textured silicon carbide was fabricated via anisotropic grain growth. Large, platelike grains were grown from a fine-grained sintered matrix which had been seeded with ≤2% SiC platelets. The seeds were initially incorporated with preferred orientation during the green-state forming process and this resulted in oriented growth of the platelike grains. The development of texture in the samples was evident from microstructure observations and X-ray diffraction analysis.