2,618 research outputs found
Potential influences on suicide prevalence in comparisons of UK post-industrial cities
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Catastrophic volcanism as a cause of shocked features found at the K/T boundary and in cryptoexplosion structures
The presence of quartz grains containing shock lamellae at the Cretaceous/Tertiary (K/T) boundary is viewed by many as the single most compelling evidence of meteoritic or cometary impact because there is no known endogenous mechanism for producing these features. Similarly the presence of shocked quartz, shatter cones, coesite and stishovite at cryptoexplosion structures is comonly taken as conclusive evidence of impact. However, several recent studies have cast doubt on this interpretation. It is argued that basaltic volcanism, although not normally explosive, can under exceptional circumstances produce overpressures sufficiently high to produce shock features. The exceptional circumstances include a high content of volatiles, usually CO2, and no preestablished pathway to the surface. Rapid cooling of the saturated basaltic magma can occur if it underlies a cooler more evolved magma in a chamber. Initial slow cooling and partial exsolution of the volatiles will cause the density of the basaltic magma to become less than that of the overlying magma, leading to overturning and mixing. Gas will escape the magma chamber along planar cracks once the pressure becomes sufficiently high. In the vicinity of the crack tip there is a smallscale deviatoric stress pattern which is thought to be sufficiently high to produce transient cracks along secondary axes in the quartz crystals, causing the planar features. The CO2-rich fluid inclusions which have been found along planar elements of quartz in basement rocks of the Vredefort Dome were likely to have been emplaced by such a process. If the mechanism described is capable of producing shocked features as above, it would require a reassessment of the origin of many cryptoexplosion structures as well as seriously weakening the case for an impact origin of the K/T event
Characterisation of dispersions within annealed HVOLF thermally sprayed AlSnCu coatings
High velocity oxy-liquid fuel (HVOLF) AlSnCu coatings are characterised following annealing for up to 5 hours at 300°C. A combination of statistical analysis of BSE images and TEM observations demonstrate the decrease in the number of sub-micron and nanoscale Sn particles with annealing, commensurate with a decrease in the coating microhardness. TEM evidence further suggests the coarsening of nanoscale Sn through a mechanism of a liquid phase migration within the Al matrix. EELS and EFTEM additionally allow the identification of the precipitation of theta'
Destination image in travel magazines: A textual and pictorial analysis of Hong Kong and Macau
Based on the analyses of texts and pictures in the top six outbound travel magazines in Mainland China, this article presents an evaluation of the destination images of Hong Kong and Macau as portrayed in 88 travel articles over a three-year period. The results showed that the projected destination images of Hong Kong and Macau were dominated by attributes related to culture, history, and art and leisure and recreation. Hong Kong was often described by image attributes such as places and attractions, shopping, cuisine and food, hotels, and the creative industries. For Macau, history and heritage, places and attractions, gambling, cuisine and food, and hotels were the most often reported. During the study period, Hong Kong and Macau witnessed several significant changes in the image attributes featured in both texts and pictures. These changes were partly influenced by news and events over the period. In this article, implications for destination marketing organizations and directions for future research were suggested
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Assessment of approaches to obtain ebullition pressures for organophilic clay blankets
The objective of this study is to compare two experimental approaches to characterize the ebullition pressure (or air-entry suction) of initially water-saturated organophilic clay blankets. The first is an indirect approach using the water-retention curve (WRC) and the second is a direct approach using ebullition experiments. The WRC along with the hydraulic conductivity of organophilic clay blankets in saturated and unsaturated conditions were measured using a flexible-wall permeameter with suction-saturation control. This device was also adapted to measure the ebullition pressure and the air permeability. The comparison of the experimental approaches was performed on organophilic clay blanket specimens in different initial conditions (unrinsed and rinsed to remove loose fines) under high and low effective confining stresses (20 and 5 kPa). The indirect estimates of air-entry suction from the WRC were similar to those obtained from the ebullition tests. This good agreement between the two approaches may add flexibility to the development of design specifications for capping systems. The hydraulic properties were found to be sensitive to rinsing and effective stress, with greater hydraulic conductivity and air permeability for the rinsed specimen due to the removal of fines, and greater air-entry suctions for specimens under higher effective stress
Development of a speech autocuer
A wearable, visually based prosthesis for the deaf based upon the proven method for removing lipreading ambiguity known as cued speech was fabricated and tested. Both software and hardware developments are described, including a microcomputer, display, and speech preprocessor
The application of tripod polishing and focused ion beam milling to the TEM specimen preparation of HVOF thermally sprayed coatings
The microstructure of high velocity oxy fuel thermally sprayed coatings is highly anisotropic and inhomogeneous. Tripod polishing has enabled the preparation of samples with up to 0.5mm diameter electron transparent areas, where a statistically significant number of features could be examined. Conversely, FIB has been used to prepare TEM samples for site-specific analysis of sub-micron regions of interest, e.g. for the interface characterisation between metallic coatings and the substrate, or the study of secondary precipitation on pre-existing phases in cermet coatings
Coagulation equations with mass loss
We derive and solve models for coagulation with mass loss
arising, for example, from industrial processes in which
growing inclusions are lost from the melt by colliding with the wall of the vessel. We consider a variety of loss laws and a variety of coagulation kernels, deriving exact results
where possible, and more generally reducing the equations
to similarity solutions valid in the large-time limit.
One notable result is the effect that mass removal has on gelation: for small loss rates, gelation is delayed, whilst above a critical threshold, gelation is completely prevented. Finally, by forming an exact explicit solution for a more general initial cluster size distribution function, we illustrate how numerical results from earlier work can be interpreted in the light of the theory presented herein
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