Publications by authors named "David R Dixon"

This article was migrated. The article was marked as recommended. Background Physicians are typically appointed to leadership roles within health care organizations on the basis of individual accomplishments in research, education, and/or clinical care.

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Quantification and comparison of the dewatering characteristics of fifteen sewage sludges from a range of digestion scenarios are described. The method proposed uses laboratory dewatering measurements and integrity analysis of the extracted material properties. These properties were used as inputs into a model of filtration, the output of which provides the dewatering comparison.

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Drying pans are used during wastewater treatment (WWT) to store, stabilise and dry residual solids. The pans are filled with sludge that dries via exposure to sunshine and wind. We propose that drying pans be operated based on dry stacking principles, a technique with proven success in the mineral processing industry.

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Force-separation measurements between Giardia lamblia cysts and an inorganic oxide (silicate glass) have been obtained by using an atomic force microscope (AFM). The cysts are compressible on the scale of the loads applied during force measurement, with the surface compressibility expressed in terms of an interfacial spring constant (K(int)). The force of interaction prior to this Hookean region, on approach, is long-range and repulsive.

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Background: Using survey instruments to assess physicians' attitudes toward electronic health record (EHR) adoption has been an ongoing area of research. No instrument has emerged for widespread use.

Objective: We used a theoretically-based, 37-question survey instrument to assess attitudes toward electronic (e-) prescribing adoption in the context of an existing EHR.

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The effect of high hydrostatic pressures on the ecotoxicological profile of pollutants is an unexplored research area. Using Pomatoceros lamarcki as a surrogate organism for this eco-barotoxicological study, it was found that in a 48 h larval bioassay with water accommodated fractions (WAF) of crude oil of up to 15.1 mg L(-1) (total hydrocarbon content) and hydrostatic pressures up to 300 bar (3000 m), an additive response was found (p < 0.

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A comparison of the dewaterability of a range of water treatment plant sludges has been completed through computation of dewatering performance indicators for a diaphragm filter press. Real parameter data, obtained from the characterisation of alum and ferric sludges, generated under precisely controlled conditions, was used for input to a phenomenological model. Comparisons of dewaterability based on throughput curves largely agree with previous analysis of the underlying parameter data.

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Owing to its widespread occurrence in drinking water supplies and its significant resistance to environmental stresses, Cryptosporidium parvum is regarded as one of the most important waterborne microbial parasites. Accordingly, a substantial research effort has been aimed at elucidating the physical, chemical and biological factors controlling the transport and removal of Cryptosporidium oocysts in natural subsurface environments and drinking water treatment facilities. In this review, a multi-scale approach is taken to discuss the current state-of-knowledge on Cryptosporidium-sand interactions at a nano-scale, bench-scale and field-scale relevant to water treatment operations.

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Comet and agarose gel electrophoresis (AGE) assays were used to show that haemocytes (blood cells) and gill tissues of vent mussels, Bathymodiolus azoricus, are sensitive to hydrostatic pressure change, but can repair DNA damage induced by retrieval from 840 m to the sea surface. In contrast, animals collected from 1700 m survived for only a few days in the laboratory, which was reflected in their poor DNA quality. These findings support the hypothesis of a physiological barrier to survival around 1000-1500 m depth, which these results show affects both vent and non-vent species alike.

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Levels of DNA strand breakage were measured, using the comet assay, in cells from vent mussels, Bathymodiolus azoricus, from three contrasting vent fields on the mid Atlantic Ridge. Different levels of DNA damage were recorded in untreated mussels, shortly after collection, and it was animals from the shallowest, and less active, Menez Gwen vent field (840-m depth), which showed the greatest amount of damage. In contrast to animals from two deeper and putatively more toxic sites, Menez Gwen animals went on to repair this damage and were able to survive under laboratory conditions at 1 bar pressure for several months.

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The last 25 years have seen major advances in the field of mammalian genotoxicology, particularly with the advent of molecular methods, some of which have spilled over into the relatively new field of eco-genotoxicology, which aims to evaluate the impact of contaminants on the natural biota. Unlike mammalian genotoxicology, where the focus is centred on a limited number of model species, efforts in the marine field have generally lacked coordination and focus, with the result that progress has been somewhat slow and fragmented. However, it is recognized that at the DNA and chromosome levels, marine invertebrates express qualitatively similar types of induced damage to that found in higher organisms (e.

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Oocysts of C. parvum have been associated with several waterborne outbreaks of gastro-enteric disease. Currently, one of the main barriers to oocyst contamination of drinking waters is provided by sand-bed filtration.

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The marine environment provides a sink for a host of toxic chemicals, directly or inadvertently, released as a result of human activity. Some of these chemicals have the potential to act as aneugens, substances that cause numerical chromosomal aberrations (NCAs). NCAs are one of the most important classes of genetic abnormality and are implicated in a variety of deleterious effects, including premature ageing, birth defects and cancer.

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Although the effects of heavy metals on marine invertebrate species are well studied in term of their toxicity and bioaccumulation, less is known about their genotoxicity. The aim of this investigation was to assess the DNA damaging potential of cadmium (Cd) in an important pollution sentinel organism, the mussel Mytilus edulis. Cadmium is one of the most toxic and widespread heavy metals found in the marine environment, and is a recognised carcinogen in mammals.

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