The relationship of alignment hyperacuity to stereopsis

Human ability to monocularly detect spatial misalignment is functionally more precise than predicted by the diameter of one foveal cone. The spatial thresholds for vernier alignment are approximately 8 to 13 arc seconds of visual angle, which is more sensitive than expected. Although threshold stereopsis (another hyperacuity) seems to be approximately double alignment hyperacuity values, studies have not conclusively shown a definite relationship to ex1st. Additionally, these measurements have not been widely tested in clinical settings. This study examines the correlation between threshold stereoacuity and the monocular alignment hyperacuity measures. Twenty six subjects were evaluated measuring threshold stereopsis with the Mentor BVAT II Visual Acuity Tester and monocular alignment hyperacuity with software designed at Pacific University College of Optometry. This study supports a relationship of sum of one standard deviation of hyperacuity data distributed for each eye with stereopsis. However, the relationship is not statistically significant, most likely due to the lack of testing precision and variability in individual performance, specifically in binocular function and appreciation of stereopsis. Increased knowledge in the areas of monocular alignment hyperacuity and threshold stereopsis may aid optometric practitioners to better understand how these two factors play a role in such clinical conditions as unexplained asthenopia, amblyopia, strabismus and stereoacuity potential. However, clinical testing of an individual patient would not seem appropriate with this testing paradigm

Characterising rag-forming solids

In oil sands froth treatment, an undesirable intermediate layer, often accumulates during the separation of water-oil emulsions. The layer referred to as rag layer is a complex mixture of water, oil, solids and interfacially active components. The presence of a rag layer has a detrimental impact on the separation of water and fine solids from diluted bitumen. The current study focuses on characterisation of solids from a rag layer forming stream of a naphthenic froth treatment plant in an attempt to understand the mechanism of rag layer formation. Through detailed characterisation of rag-forming and non-rag-forming solids, the mineralogy of solids and their contamination were shown to be critical to rag layer formation. The iron-based minerals such as siderite and pyrite were found to be enriched within the rag layer. Analysis of surface organic complexes confirms a high level of organic matter associated with these solids through the binding of carboxylic acid group with iron on solids, resulting in a surface hydrophobicity susceptible for rag layer formation

Whey protein microgel particles as stabilizers of waxy corn starch + locust bean gum water-in-water emulsions

Food-grade whey protein isolate (WPI) microgel particles were investigated as a particle stabilizer of water-in-water (W/W) emulsions. The microgel particles were produced via the novel method of forcing coarse particles of a pre-formed thermally processed WPI protein gel through a jet homogenizer. The Z-average particle size was 149 ± 89 nm but the particles showed a strong tendency for aggregation when the pH was lowered from pH 7 to 4, when the zeta potential also switched from -17 to +12 mV. The viscoelasticity of suspensions of the particles, measured between 1 and 15 vol.% (0.02 and 3 wt.%) increased with concentration and was also higher at pH 4 than pH 7. However, all the suspensions were only weakly shear thinning, suggesting that they did not form very strong networks. The particles were added (at 1-15 vol.%) to a model W/W system consisting of waxy corn starch (S) + locust bean gum (LBG) that normally shows phase separation when the components are mixed at 90 °C then cooled to room temperature (22-25 °C). At 10 to 15 vol.% particles and pH 4, visual observation showed striking inhibition of phase separation, for a period of up to 1 year. Confocal laser scanning microscopy suggested that under these conditions extensive aggregation of the microparticles occurred within the starch phase but also possibly at the W/W interface between the starch-rich and gum-rich regions, supporting a Pickering-type mechanism as responsible for the enhanced stabilization of the W/W emulsion by the microgel particles

High protein lupins: diversifying the pulse industry in western Canada

The pulse crop industry in Canada has grown rapidly in the past decade, with approximately 3.6 million tonnes of production from 2.9 million hectares in 2001, compared to 1.0 million tonnes of production from 0.6 million ha in 1991 (Pulse Canada, 2003). In order to achieve the pulse crop industry’s goal of sustainable annual crop rotations based on a 20-25% legume component, additional pulse crops are developed so that all prairie regions have at least two legume crop choices that provide economic return. Preliminary work in Alberta has indicated that new European genotypes of Lupinus angustifolius L. (narrow-leaf lupin) are adapted to the prairies. The production of a pulse crop with 35-40% protein and 6-8% crude fat could have beneficial implications for livestock feed (aquaculture, dairy, poultry and swine). The fatty acid profile of lupin seed has been noted as having excellent emollient properties for the cosmetic industry. The low amount of oil (8-10%) means that the seed does not have to be de-oiled, which is the case for some soy-based processes. The excellent tolerance for acidic soils also provides an area for pulse expansion in parts of Canada that currently do not have pulse crop options due to low soil pH