Inception of Sediment Transport on Steep Slopes

Using dimensional and theoretical analysis together with available experimental data, it has been shown how flow conditions and stream bed slope affect the beginning of sediment transport. The dimensional analysis shows that, in general, the Shields parameter is a function of the stream slope and the Reynolds number. The traditional Shields diagram is a special case of this relationship for a zero of near zero slope. The theoretical treatment is an adaptation of work from earlier authors, which is used in conjunction with dimensional analysis to show the interdependence of flow conditions and forces contributing to the critical point of particle motion. Additional experiments are recommended.     

Fabrication of waveguide tapers by semitransparent mask photolithography

An improved process for semitransparent mask lithography is described. The uniformity of mask transmittance is increased by adapting the electron beam exposure field size to a binary multiple of the pattern period. In addition surface roughness of resist patterns is reduced by exposure of the resist-coated sample to an acetone atmosphere which results in negligible micro roughness.

Using this process waveguide tapers employing a symmetric layer structure were fabricated. The tapers exhibit fiber-chip coupling losses of 1.6 dB after Fresnel correction and lateral alignment tolerances of ±2.2 μm for 1 dB excess loss. These values are comparable to results obtained for waveguide tapers fabricated using direct write electron beam lithography. This proves the described process to be suitable for the fabrication of relief type structures for optoelectronic integrated circuits.     

Supplementary anti-hepatitis C virus (HCV) testing with 2nd and 3rd generation recombinant immunoblot assay and matrix applied to enzyme immunoassay positive sera and comparison with HCV-RNA detection

Following the same general principles of its two predecessors in 1973 and 1986, the 1996 National Roadside Survey of weekend, nighttime drivers in the 48 contiguous states interviewed and breath tested over 6000 noncommercial four-wheel vehicle operators between September 6 and November 9, 1996. Results indicated that the total number of drinking drivers fell by about one-third between 1986 and 1996; however, there was no significant change in the number of drivers at blood alcohol concentrations (BACs) at or above 0.05. Compared to 1973, the proportion of women drivers on the roads during weekend nights has increased significantly. Moreover, relative to males, the proportion of female drivers who have been drinking has increased over the last decade. The number of drivers under the age of 21 with a BAC at or above 0.10 decreased significantly from 1986 to 1996.     

Fundamentals of MRAM Technology

Developments in portable communication and computing systems are creating a growing demand for nonvolatile random access memory that is dense and fast. None of the existing solid-state memories can provide all the needed attributes in a single memory solution. Therefore, to achieve the required multiple functionality requirements, a number of different memories are being used while compromising performance and adding cost to the system. Magnetoresistive Random Access Memory (MRAM) has the potential to replace these memories in various systems with a single, universal memory solution. Key attributes of MRAM technology are nonvolatility and unlimited read and write endurance. In addition, MRAM can operate at high-speed and is expected to have competitive densities. In this paper we describe several fundamental technical and scientific aspects of MRAM with emphasis on recent accomplishments that enabled our successful demonstration of a 256 kbit memory chip.     

Excimer Laser Micro Texturing of Cold Forging Tool Surfaces - Influence on Tool Life

In bulk metal forming the tribological state is significantly dependent on the surface topography of tool and workpiece. To provide the process with an improved tribological behaviour in some cases the billet's surface is prepared by shot blasting. Micro texturing of the tool surface provides an additional opportunity to optimise the frictional conditions.This paper deals with the investigation of micro texturing of the surface of TiN-coated tools with regard to their tribological behaviour in the field of cold forging. The micro textures are applied by excimer laser radiation. Tool life investigations in an industrial press shop yield that the tool surface can be improved significantly leading to higher tool life.     

Hearing loss from combined exposures among petroleum refinery workers

Seventy-three consecutive cases of childhood acute lymphoblastic leukemia (ALL) diagnosed and managed in Queen Mary Hospital over a 10-year period from 1985 to 1994 were retrospectively analysed for their presenting features and treatment outcome. The 48 boys and 25 girls ranged in age from 0.4 to 14.2 years (median: 4.3 years). Bone and joint pain was a relatively common presenting feature besides fever, hepatosplenomegaly and lymphadenopathy. Immunophenotyping of blast cells showed: 51 B-cell precursor ALL, one B-ALL, 10 T-ALL and three myeloid-antigen positive ALL. Eight cases were unclassified since immunophenotyping had not been performed. Out of the 73 patients, treatment outcome was analysed in 20 cases treated with UKALL-VIII regimen and 28 cases treated with either the UKALL-XI regimen or the Hong Kong Children Cancer Study Group (HKCCSG) protocol which was modelled upon UKALL-XI. Although complete remission rates were similar between the two groups, patients treated with the former regimen that was less intensified suffered more relapses than the latter (56 per cent versus 21 per cent, P = 0.04). There were, however, no significant differences both in event-free survival (38.2 +/- 11.2 per cent versus 71.3 +/- 9.3 per cent, P = 0.12) and overall survival (70.0 +/- 10.2 per cent versus 79.6 +/- 8.3 per cent, P = 0.41) between the two groups at 3 years by long-rank test. With the use of risk-directed therapy and improved supportive care, two-thirds of our patients are able to enjoy long-term event-free survival.     

The development of drawing in children with congenital focal brain injury: evidence for limited functional recovery

Children with pre- or perinatal injury to right hemisphere (RH) brain regions show impairment of spatial integrative functions similar to that observed among adults with comparable injury. Unlike adults, children show considerable improvement with development on a range of spatial construction tasks which require spatial integration. Such gains could reflect true recovery of spatial integrative abilities. Alternatively, the improvement could be more limited in scope, reflecting the development of compensatory strategies which are task specific and allow the children to circumvent, rather than overcome, their primary spatial disorders. The studies presented here examined this distinction within the context of drawing tasks in which the child was first asked to draw a house and then an impossible house. The impossible house task was designed to examine the extent to which children rely on graphic formulas in generating organized drawings. The results showed that while all of the children with RH injury make considerable progress in free drawing into the school age period, they are very reliant on the use of graphic formulas. When given a task which requires them to alter their drawings, they did not change the spatial configuration of the depicted object. Rather they found alternate ways to render the object 'impossible'.     

Heck–Matsuda Arylation of Olefins Through a Bicatalytic Approach: Improved Procedures and Rationalization

The scope of the palladium‐catalyzed Heck–Matsuda reaction, proceeding through the catalytic activation of anilines into the corresponding diazonium salts, has been considerably extended and is now working with deactivated electrophiles. Two different procedures, using catalytic amounts of both palladium and acid, have been optimized allowing the concept of bicatalysis to cover the complete electronic range of anilines. These environmentally friendly procedures proceed under very mild conditions, at room temperature in methanol, and only generate tert‐butyl alcohol, water and nitrogen as by‐products. Rationalization of reaction outcomes encountered in this work has been discussed with the support of computational studies.