Emergency department(ED) is one of the busiest clinical units in Winnipeg Victoria Gen-eral Hospital (VGH) which faces the challenge of patients’ long waiting-time as increas-ing healthcare demand and limited resources. This research investigates the critical factors of the ED operation to enhance the operational efficiency using simulation modeling and optimization. The contribution of this research is the integration of simulation and optimization for the performance improvement of ED operations. Discrete-events simula-tion (DES) methodology provides a cost-effective tool to analyse the performance of the ED operations and evaluates the potential alternatives. Design of experiments (DOE) and Scatter search (SS) of model optimization are proposed to search the ED potential capaci-ty for waiting-time reduction. The patient-flow is accelerated along with the waiting-time reduction, which results in better efficient patient throughput in the ED. A specific strate-gy is suggested to improve the ED operation based on the simulation model.

Thesis (Ph.D.) -- Adelaide University, Dept. of Physics and Mathematical Physics, 2001. / Includes a copy of an article co-authored by the author during the preparation of this thesis. Bibliography: leaves 253-266. Also available electronically.

Thesis (Ph.D.) -- Adelaide University, Dept. of Physics and Mathematical Physics, 2001. / Bibliography: leaves 253-266. Also available in print form.

The quality of an underwater image is degraded due to the effects of light scattering in water, which are resolution loss and contrast loss. Contrast loss is the main degradation problem in underwater images which is caused by the effect of optical back-scatter. A method is proposed to improve the contrast of an underwater image by mitigating the effect of optical back-scatter after image acquisition. The proposed method is based on the inverse model of an underwater image model, which is validated experimentally in this work. It suggests that the recovered image can be obtained by subtracting the intensity value due to the effect of optical back-scatter from the degraded image pixel and then scaling the remaining by a factor due to the effect of optical extinction. Three filters are proposed to estimate for optical back-scatter in a degraded image. Among these three filters, the performance of BS-CostFunc filter is the best. The physical model of the optical extinction indicates that the optical extinction can be calculated by knowing the level of optical back-scatter. Results from simulations with synthetic images and experiments with real constrained images in monochrome indicate that the maximum optical back-scatter estimation error is less than 5%. The proposed algorithm can significantly improve the contrast of a monochrome underwater image. Results of colour simulations with synthetic colour images and experiments with real constrained colour images indicate that the proposed method is applicable to colour images with colour fidelity. However, for colour images in wide spectral bands, such as RGB, the colour of the improved images is similar to the colour of that of the reference images. Yet, the improved images are darker than the reference images in terms of intensity. The darkness of the improved images is because of the effect of noise on the level of estimation errors.

Optical sensing and imaging inside heavily scattering media are of intense interest because of their importance in biomedical, environmental, and material inspection applications. When coherent light interacts with scatterers, bright and dark intensity regions form, a phenomenon known as speckle. Often viewed as being detrimental, speckle can be exploited to yield useful information with a correlation analysis.<br> <br>A coherent method is presented for the imaging of a hidden object moving within thick and randomly scattering media using speckle intensity correlations over object position, with the possibility of accessing super-resolution information. With prior information about the moving object's motion, spatial speckle intensity correlations as a function of object position can reveal the hidden object's relative refractive index distribution. Our experimental evidence shows that it is feasible to image complex aperture-type moving objects and circular patches inside scatter that is a magnitude of order heavier than other comparable imaging modalities. Images of the moving object were obtained from speckle intensity correlation data using phase retrieval. Biological tissue was used to demonstrate the possibility of in vivo deep-tissue imaging. Speckle intensity correlations are shown to be sensitive to both the scattering strength of the embedded object and the environment, both of which are useful for sensing. We present a general theory that describes this influence of the background scattering medium and allows for imaging a hidden moving object. Additionally, we present a method to improve the sensitivity of speckle correlography in remote optical metrology. By placing a scattering slab in front of the detector, we demonstrate enhanced sensitivity, detecting the subwavelength in-plane displacement of a remote diffuse object.

Balanites maughamii is an ecologically and culturally valuable tree species, heavily impacted by elephants, which strip bark selectively off the largest trees, increasing their susceptibility to fire damage. Elephants also break intermediate sized trees extensively, keeping them trapped in non-reproductive stages. The trees can however survive breaking, stripping and · toppling by elephants, as well as top kill by fires, because they resprout vigorously in response to damage. They also produce root suckers. independently of disturbance. Vegetative reproduction buffers the populations from the infrequent recruitment of seedlings, and facilitates the maintenance of populations over the short term. Balanites maughamii trees are reliant on African elephants (Loxodonta africana) for seed dispersal and to provide a germination cue through mastication. In the absence of elephants, the population experiences a recruitment bottleneck, but root suckers functionally replace seedlings and fill the "recruitment gap", so over the short term, the population is resilient. In all populations, whether elephants are present or not, another hurdle affects recruitment, and it is seed limitation due to seed predation pre- and post- dispersal. Cafeteria experiments revealed that bushveld gerbils (Tatera leucogaster) were removing many seeds but do not scatter- or larder-hoard. They are simply seed predators.

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