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Assessing the effects of drug use on the transmission dynamics of HIV/AIDS
No full textResearch article.Drug misuse has been recognized to have a significant
impact on the spread of HIV/AIDS epidemic. A deterministic model to
theoretically assess the contribution of drug misuse to the spread of
HIV/AIDS is investigated. The basic reproduction number of the
model is determined and stability of equilibria analysed. The disease free
equilibrium point is shown to be globally asymptotically stable
when its corresponding basic reproduction number is less than unity.
The Centre Manifold theory is used to show that the endemic
equilibrium point is locally asymptotically stable when its
corresponding reproduction number is greater than unity. The results
obtained from the analysis of the basic reproduction number show that
drug use increases the basic reproduction number. This suggests that
drug misuse has the potential to fuel the epidemic. Results from numerical
simulations show that HIV infected drug abusing individuals progress to the AIDS
stage and die at a faster rate than their corresponding HIV infected parts
Design of Comminution Circuits for Improved Productivity Using a Multi-Objective Evolutionary Algorithm (MOEA)
No full textThe performance of a processing plant has a large impact on the profitability of a mining operation, yet plant design optimisation decisions are based on past experience and intuition rather than on scientific analysis. Genetic algorithms as a tool for circuit analysis in plant design and
optimisation was considered. The multi-objective evolutionary algorithm initialises the plant design and optimisation based on experimental results, which are used to formulate and determine the objective function values. A simulation was conducted to assess the performance of candidate solutions. The two optima are then traded-off
using cost objective, which is sought to be minimized. Once an optimum was selected, the circuit mass balance and equipment design was performed, bringing the theory of
network design and genetic algorithms into unison. Results of the study provide financial benefits, optimal parameter settings for the comminution equipment and ultimately better plant performance
The conundrum of conservation agriculture and livelihoods in Southern Africa
No full textFull Length Research PaperLow crop productivity, food insecurity, hunger and malnutrition; inadequate farming knowledge and skills, implements and inputs are characteristic of smallholder agriculture in Southern Africa. Many
researchers argue that conservation agriculture can guarantee higher crop productivity, food security,improved livelihoods and environmental protection, better than the unsustainable traditional systems of slash and burn practices. In this paper, we present the results of a meta-analysis of over 40 academic publications to review conservation agriculture?s role in influencing desired livelihood outcomes in
Southern Africa. We conclude that the effectiveness of conservation agriculture towards better livelihood outcomes in Southern Africa remains debatable, especially when supportive government
policies are lacking
Yellow maize with high B-carotene is an effective source of vitamin A in healthy Zimbabwean men.
No full textBackground: The bioconversion ef?ciency of yellow maizeb-carotene to retinol in humans is unknown.Objective: The objective of this study was to determine the vitamin. A value of yellow maizeb-carotene in humans.
Design: Highb-carotene?containing yellow maize was grown in
a hydroponic medium with 23 atom% 2H2O during grain development.
Yellow maizeb-carotene showed the highest abundance of
enrichment as [ 2H 9]b-carotene. Eight healthy Zimbabwean men volunteered for the study. On day 1 after a fasting blood draw,
subjects consumed 300 g yellow maize porridge containing 1.2 mg b-carotene, 20 g butter, and a 0.5-g corn oil capsule. Onday 8, fasting
blood was drawn, and subjects consumed 1 mg [13C10]retinyl acetate
in a 0.5-g corn oil capsule and 300 g white maize porridge with 20 g butter. Thirty-six blood samples were collected from each subject over 36 d. Concentrations and enrichments of retinol andb-carotene
in labeled doses and serum were determined with the use of HPLC, gas chromatography?mass spectrometry, and liquid chromatography? mass spectrometry.
Results: The area under the curve (AUC) of retinol from 1.2 mg yellow maizeb-carotene was 72.9 nmol ? d, and the AUC of retinol
from 1 mg retinyl acetate 13C10 was 161.1 nmol? d. The conversion factor of yellow maizeb-carotene to retinol by weight was 3.26
1.5 to 1.
Conclusion: In 8 healthy Zimbabwean men, 300 g cooked yellow maize containing 1.2 mgb-carotene that was consumed with 20.5 g
fat showed the same vitamin A activity as 0.38 mg retinol and provided 40?50% of the adult vitamin A Recommended Dietary Allowance
Exploring the effects of parameter heterogeneity on the intrinsic dynamics of HIV/AIDS in heterosexual settings
No full textA sex-structured staged progression model for heterosexual transmission dynamics of
HIV/AIDS in a community to theoretically assess the e?ects of gender parameter
accounting for population heterogeneity is formulated and analyzed. The basic model
without this parameter is analyzed, and then extended to include gender heterogeneity in
order to explore its role on the transmission dynamics of the disease.Mathematical properties
including epidemic thresholds known as reproductive numbers are derived. The
models are numerically analysed using some demographic and epidemiological parameters
for Zimbabwe. These simulations suggest that the use of identical gender attributes
simpli?es computation at the expense of reality as it underestimates the size of the epidemic by 5%. This study demonstrates that the use of gender related parameter in the
transmission dynamics of HIV gives a better estimate of the prevalence of the epidemic
and should be given prominence
Non-deliberate organic input in relation to land use in a semi-arid AGRO-ecosystem in northern Zimbabwe
No full textTropical and Subtropical Agroecosystems, 14 (2011): 709 - 714Animals via excretory processes are important in nutrient cycling in agro- ecosystems and can supply nutrients (nitrogen and phosphorus) at rates comparable to major nutrient sources. Land use influenced nutrient levels with mixed areas (wildlife and livestock) indicating the potential of improved nutrient cycling than wildlife and livestock as stand alones. The time of application for both plant residues and faecal material may influence the nutrients available to the crops. The time of application of faecal material should be aimed to increase N and P availability which is during the early dry season. Nitrogen levels in faecal material were comparable to levels found in legume cover crops indicating the high quality of faecal material. This study reports that non deliberate organic inputs by livestock and wildlife can be important in fertility improvement in mixed farming systems in northern Zimbabwe
Vice Chancellor's Sixteenth Graduation Ceremony Speech
No full textAddress by Professor Lindela Rowland Ndlovu, Vice Chancellor at the Sixteenth Graduation Ceremon
Effective Maintenance and Production Planning using Linear Programming and Simulation at NF Oil Plant
No full textProceedings of the 40th Annual Operations Research Society of Southern Africa (ORSSA) Conference, 18-21 September 2011, Elephant Hills, Victoria Falls, ZimbabweThere is always a conflict betwee maintenance and production teams in companies with the need to achieve individual set targets. Looking from a strategic point of view the goal should be for the growth of the organization. This paper sets to demonstrate the development of a production and maintenance system for the NF Oil Plant, using linear programming and simulation tools. The Simplex Method was
used in Production Planning and Simulation of the plant was done to verify applicability of Maintenance and Production plans. Through experimentation, significant savings on boiler fuel of up to 27% are shown to be possible with less than 3% reduction in anticipated contribution. In addition, more than 15% increases in throughput for some plant sections was demonstrated, with a further 7% increase in worker utilisation
Vice Chancellor's Twelfth Graduation Ceremony Speech
No full textAddress by Professor Lindela Rowland Ndlovu,
Vice Chancellor at the Twelfth Graduation Ceremony
Vice Chancellor's Installation Speech
No full textAddress by Professor Lindela Rowland Ndlovu, Vice Chancellor Designate of NUST on the Occasion of the Installation of the Second Vice -Chancellor during the Eleventh Graduation Ceremony