DSpace at My UniversityThe DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.http://172.16.0.88:8080/xmlui2017-09-21T15:47:26Z2017-09-21T15:47:26ZMathematical Models for the Dynamics and Control Strategies for Rotavirus DiseaseNamawejje, Hellenhttp://hdl.handle.net/123456789/232017-02-15T08:33:52Z2016-04-01T00:00:00ZMathematical Models for the Dynamics and Control Strategies for Rotavirus Disease
Namawejje, Hellen
This dissertation investigates a mathematical model for the dynamics and control strategies for rotavirus disease, first, to study the effect of treatment and vaccination controls on the dynamics of the disease, stability analysis of disease-free-equilibrium point (DFEP) and endemic equilibrium point (EEP) were performed. The computational results show that DFEP is globally asymptotically stable if the basic reproduction number, R0 < 1 and unstable if R0 > 1. The EEP exits if and only if the effective reproduction number, Re > 1. Numerical simulations obtained show that treatment and vaccination can be used to fight rotavirus disease. To assess the best control strategy among vaccination, treatment and health education campaigns control measures in the dynamics of the rotavirus, we analysed the conditions for optimal control using the optimal control theory to find the optimal curve for each of the controls. Our results show that control measures have a very desirable effect for minimising the number of infected individuals as well as maximising the number of susceptibles and that multiple control strategies are more effective than a single control strategy. Furthermore, we obtained that, health education campaigns should not be implemented alone because they are less effective at the beginning if implemented alone but the combination which involves vaccination gives better results.
To investigate the effect of vaccination when administered in three doses on the dynamics of
the disease. Using the comparison approach the global stability of the DFEP with vaccination
was computed. In case of no vaccination, a forward bifurcation exits whenever the basic reproduction number, R0 > 1. Numerical results show that vaccination reduces the degree of
susceptibility and infectiousness when children are exposed to rotavirus disease.
Using the pontryagin’s maximum principle to asses the impact of three dose vaccination and
treatment controls, the performed simulations show that with no control, infection will disappear after 75 days, with treatment only, it takes 55 days, with vaccination only, it takes between 30 to 40 days and if both measures are implemented it takes only 10 days to disappear, thus infection is wiped out in a very short period compared to when only one strategy is used.
2016-04-01T00:00:00ZAnalysis and Simulation of Nanofluid Flowand Heat Transfer in a Porous PipeKhamis, Sara Abdallahttp://hdl.handle.net/123456789/162017-02-09T12:43:49Z2016-04-01T00:00:00ZAnalysis and Simulation of Nanofluid Flowand Heat Transfer in a Porous Pipe
Khamis, Sara Abdalla
The study of fluid flow and heat tr ansfer through a cylindrical pipe and channel with porous
boundaries are important research area due to its wide range of applications in engineering and
industrial processes. Some practical applications include problems dealing with transpiration
cooling, gaseous diffusion in order to produce fuel for nuclear reactors, controlling boundary
layer flow over aircraft wings by injection or suction of fluid out of or into the wing, lubrication
of porous bearings, petroleum technology, ground water hydrology, seepage of water in river
beds, purification a nd filtration pr ocesses. A na nofluid is the sus pension of nan oparticles in
a base fluid. Nanofluids ar e pr omising fo r he at tr ansfer enhancement due to th eir high thermal
conductivity. For practical applications of nanofluids research in nanofluids convection are
important. Owing to their enhanced properties, nanofluids can be used in a plethora of technical
and biomedical applications such as nanofluid coolant which include electronics cooling,
vehicle cooling, transformer cooling, computers cooling and other electronic devices cooling.
Other applications are medical applications which include magnetic drug targeting, cancer therapy
and safer surgery by cooling.
This study considered the detailed analysis of laminar flow behavior and heat transfer using
this innovative fluid as working fluid through a pipe and channel with porous boundaries for
both steady and unsteady scenarios. We considered water-based nanofluids where copper and
alumina were used as nanoparticles. The appropriate mathematical models for the problems
were derived from the laws of conservation of mass, momentum and energy balance. The governing
nonlinear Partial Differential Equations (PDE) and boundary conditions were converted
into nonlinear Ordinary Differential Equations (ODE) using appropriate similarity transformations
for the case of steady state formulated model and method of lines when unsteady situation
was considered. These equations were solved analytically by regular perturbation methods with
series improvement technique and numerically using an efficient Runge-Kutta-Fehlberg integration
technique coupled with shooting scheme and multidimensional Newton-Raphson root
finding technique.
In chapter 1, the key concepts and derivations related to fluid flow, the statement of the problem,
the objectives of the study, Significance of the study and the methodology are given. In chapter
2, the heat transfer characteristics of Berman flow of water-based nanofluids in a porous channel
with Navier slip, viscous dissipation and convective cooling is investigated. Chapter 3 the
combined effect of variable viscosity, Brownian motion, thermophoresis and convective cooling
on unsteady flow of nanofluid in a cylindrical pipe with permeable wall are analysed. In chapter
4 we investigates the effects of buoyancy force and variable viscosity on unsteady flow and
heat transfer of water-based nanofluid containing Copper and Alumina as nanoparticles. Analysis
of unsteady water-based nanofluid flow in a permeable cylindrical pipe through saturated
porous medium with the effect of buoyancy-driven force, variable viscosity and Navier slip are
examined. The useful results for the velocity, temperature, nanoparticles concentration profiles,
pressure gradient, skin friction and Nusselt number were obtained and discussed quantitatively.
The effects of important governing flow parameters on the entire flow structure were examined.
The conclusion remarks are carried out in chapter 6.
2016-04-01T00:00:00ZMathematical Modelling of Intra and Interdynamics and Control of Yellow Fever in Primate and Human PopulationsKung’aro, Monicahttp://hdl.handle.net/123456789/152017-02-09T12:31:26Z2016-04-01T00:00:00ZMathematical Modelling of Intra and Interdynamics and Control of Yellow Fever in Primate and Human Populations
Kung’aro, Monica
A deterministic mathematical model was formulated using non-linear ordinary differential equations
to gain an insight of dynamics of yellow fever (YF) between primates, human beings
and Aedes mosquito for the purpose of controlling the disease. Basic reproduction number,
R0, was computed and its sensitivity analysis with respect to epidemiological parameters was
performed to study the effect of model parameters to R0.
Results showed that R0 is most sensitive to daily biting rate of mosquitoes, recruitment rate of
vectors, probability of transmission of infection, recruitment of unvaccinated immigrants and
the incubation period for both vector and humans. Thus, for the minimization of YF transmission,
these parameters should closely be monitored. Stability analysis of disease-free equilibrium
(DFE) and endemic equilibrium (EE) points were performed to study perseverance and
condition necessary for disease interruption and control. Results showed that the DFE is locally
asymptotically stable if the rate of new infection from infected monkey to vector is less than
unity, and is globally asymptotically stable if the rate of new infection from infected vector to
human is less than unity. Lyapunov stability theory and LaSalles Invariant Principle were used
to investigate stability of EE. Results show that EE is globally asymptotically stable whenever
R0 > 1. To assess the impact of control measures on YF dynamics, we derived and analysed
the necessary conditions for optimal control using optimal control theory. Results show that
multiple optimal control strategy is the most effective to bring a stable disease-free equilibrium
compared to single and two controls. However, spray of insecticides alone was not effective
without personal protection, and optimal use of personal protection alone is beneficial to minimize
transmission of the infection to the community. Furthermore, cost-effectiveness analysis
of the optimal control measures was considered. We used incremental cost-effectiveness ratio
to investigate and compare the costs required against the health benefits achieved between two
or more alternative intervention strategies that compete for the same resource. Results showed
that combination of all strategies is the most cost-effective compared to others.
2016-04-01T00:00:00ZMolecular Diversity of Bacteria from a Municipal Dumpsite: Implications to Public HealthMwaikono, Kilaza Samsonhttp://hdl.handle.net/123456789/142017-02-09T10:36:27Z2016-04-01T00:00:00ZMolecular Diversity of Bacteria from a Municipal Dumpsite: Implications to Public Health
Mwaikono, Kilaza Samson
Despite known risks of inappropriate disposal of solid wastes; most cities in developing countries dispose waste in open dumpsite where humans, animals and microbes interact. This study was done in Arusha municipal dumpsite, Tanzania to investigate the abundance and diversity of bacteria, compare the faecal microbiota of pigs scavenging on dumpsite and indoor reared pigs, and also determine the resistance profile of enteric bacteria from the dumpsite. Domestic wastes, solid biomedical wastes, sludge from the river near the dumpsite and faecal materials of pigs were sampled. Total DNA was extracted and the variable region four (v4) of the 16S rRNA gene was sequenced using high throughput Illumina MiSeq platform. The quality control of sequences and the statistical analyses was performed using Mothur platform. A total of 8,469,294 quality sequences were generated. The mean of bacterial species per sample was 8,243. Diversity was high with an average InvSimpson index of 44.2. Thirty-five bacterial phyla dominated by Firmicutes (38%), Proteobacteria (35%), Bacteroidetes (13%) and Actinobacteria (3%) were found. Overall, 76,862 operational taxonomic units (OTUs) dominated by Acinetobacter (12.1%), Clostridium sensu stricto (4.8%), Proteinclasticum and Lactobacillus (each 3.4%), Enterococcus (2.9%) and Escherichia/Shigella (1.7%) were revealed. There was a significant difference in faecal microbiota between scavenging and indoor reared pigs. Pathogenic genera like Brucella, Rickettsia and Listeria were exclusive to scavenging pigs. In solid biomedical waste, 36.2% of OTUs were related to dehalogenation, 11.6% degraders of aromatic hydrocarbons, 8.5% chlorophenol degradation and Atrazine metabolism 8.3%, and bacteria related to pathogens were 34%. Escherichia/ Shigella, Bacilli and Proteiniclasticum were predominant enteric bacteria. Some bacteria in scavenging pigs had 99% sequence similarity to pathogenic Escherichia furgosonii, Shigella sonnei, Enterococcus faecium and Escherichia coli O154:H4. Over 50% of the isolates were multidrug resistant. The study provides a comprehensive report on diversity of bacteria in Arusha municipal dumpsite. The high species richness shows the complexity of this man-made ecosystem, and calls for further research to assess for a link between human diseases and the dumpsite. This would provide insight into proper disposal of the waste, as well as, limit the risks to human health associated with the dumpsites.
2016-04-01T00:00:00Z