Abstract. The retina performs various key operations on incoming images in order to facilitate higher-level visual processing. Since the retina outperforms existing image enhancing techniques, it follows that computational simulations with biological plausibility are best suited to inform their design and development, as well as help us better understand retina functionality. Recently, it has been determined that quality of vision is dependant on the interaction between rod and cone pathways, traditionally thought to be wholly autonomous. This interaction improves the signal-to-noise ratio (SNR) within the retina and in turn enhances boundary detection by cones. In this paper we therefore propose the first cone simulator that incorporates input from rods. Our results show that rod-cone convergence does improve SNR, therefore allowing for improved contrast sensitivity, and consequently visual perception.

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Aflatoxin resulting from the consumption of contaminated cereals has always been a concern in Kenya. The purpose of this study was to determine the economic costs of aflatoxin contamination in Meru and Tharaka Nithi counties in Kenya. A multi-stage cluster sampling using the Kenya National Bureau of Statistics (KNBS) design was used to select clusters and households. Once clusters were identified, households were selected from each cluster using a stratified random sampling method. Questionnaires were developed and pretested to determine their validity and reliability. Majority of the surveyed households associated aflatoxin contamination with an increased cost of farming, and lack of market rejection of their products by the market and brokers. Finally, an increased need for veterinary intervention was also associated with contamination. It was therefore concluded that access to the market remains a challenge to most farmers and this can only be corrected if aflatoxin is managed.

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