Extremely low threshold current 1.52 ?m InGaAsP/InP MS-DFB lasers with second-order grating

Threshold currents of 1.52 ?m InGaAsP/InPGaAsP/InP DFB lasers with second-order gratings have been reduced to 12 mA in single-longitudinal-mode operation. External differential efficiencies exceed 25%/feet with a ?/4 Si3N4 coating on the front facet.     

A multiplex ligation detection assay for the characterization of Salmonella enterica strains

A proof of principle of a multi-target assay for genotyping Salmonella has been developed targeting 62 genomic marker sequences of Salmonella related to pathogenicity. The assay is based on multiplex ligation detection reaction (LDR) followed by customized ArrayTube? microarray detection. The feasibility of the developed assay was verified in a method comparison study with conventional PCR using 16 Salmonella 'test' strains comprising eight serovars. Subsequently, the feasibility of the LDR microarray assay was also tested by analyzing 41 strains belonging to 23 serovars. With the exception of four serovars each serovar was characterized by a unique virulence associated gene repertoire. The LDR microarray platform proved to be a convenient, rapid and easy to use tool with potential in tracing a Salmonella contamination in the food chain, for outbreak studies, and to provide data for risk assessors that support bio-traceability models.     

BIOLOGICAL EXTRACTION OF METALS: THE RATE-CONTROLLING STEP

Although an enormous amount of work has been done in the area of biohydrometalJurgy, the influence of the inert solid matrix on metal extraction, and consequently the rate-controlling mechanism have not been fully understood. Actually, most studies have mainly focused on the bioextraction of metals from high-grade mineral concentrates. Such an approach is important in elucidating the diffusion and reaction phenomena that are taking place on the surface of the mineral. In reality, however, the mineral is embedded within an inert solid matrix which will have significant effects on diffusion and chemical reaction rate processes. In this work, a detailed experimental kinetic study was conducted to incorporate this factor in an attempt to quantify the rate-controlling mechanism involved. The biological dissolution of pyrite in the presence of acidophilic Thiobacillus ferrooxidans was investigated in a batch experiments on three distinct mine waste rocks. The experiments were conducted on two particle sizes and at three operating temperatures. Based on particle size and activation energies results, it was found that intraparticle mass transfer resistances were solely the rate-controlling mechanism for this process This new finding is different from that reported by other investigators who underestimated the importance of intraparticle mass transfer resistances. Also, because similar processes are ubiquitous in nature, this work should have broad applications.     

Optimal algorithms for dissemination of information in some interconnection networks

The problems of gossiping and broadcasting in one-way communication mode are considered for some prominent families of graphs. The complexity is measured as the number of communication rounds in the gossip and broadcast algorithms. The main result of the paper is the precise estimation of the gossip-problem complexity in cycles. To obtain this result a new combinatorial analysis of gossiping in cycles is developed. This analysis leads to an optimal lower bound on the number of rounds, and also to the design of an optimal algorithm for gossiping in cycles. The optimal algorithm for gossiping is later used to design new, effective algorithms for gossiping in important families of interconnection networks (cube connected cycles, butterfly networks). Furthermore, a new, effective algorithm for broadcasting in shuffle-exchange networks is developed.On leave from Comenius University, Bratislava, Czechoslovakia.     

Characterization of an Anaplasma ovis isolate from desert bighorn sheep in southern California

The aim of the present study was to validate an in vitro assay for quantifying resistant starch (RS) in foods against an in vivo model. The amount of starch escaping digestion in the small intestine of ileostomates was compared with that observed by using the in vitro assay. Subjects with ileostomies were fed five foods containing different types and amounts of RS (baked beans, pearl barley, cornflakes, and whole and ground rice). The total amount of starch escaping digestion and recovered in the effluent (ranging from 5.7% in baked beans to 0.7% in ground rice) was compared with results obtained by using the in vitro assay with an incubation time of 6 h. The assay was found to be a good qualitative predictor (r = 0.90, P < 0.05), but a poor quantitative predictor of RS amounts. Increasing the duration of incubation with alpha-amylase and amyloglucosidase to 15 h resulted in a very close agreement between results from the in vitro technique and the in vivo model. These data indicate that for a variety of foods the in vitro assay produced an excellent estimate of starch escaping digestion in the small intestine of humans.