Mathematical modelling and analysis of HIV transmission dynamics

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This thesis firstly presents a nonlinear extended deterministic Susceptible-Infected (SI) model for assessing the impact of public health education campaign on curtailing the spread of the HIV pandemic in a population. Rigorous qualitative analysis of the model reveals that, in contrast to the model without education, the full model with education exhibits the phenomenon of backward bifurcation (BB), where a stable disease-free equilibrium coexists with a stable endemic equilibrium when a certain threshold quantity, known as the effective reproduction number (Reff ), is less than unity. Furthermore, an explicit threshold value is derived above which such an education campaign could lead to detrimental outcome (increase disease burden), and below which it would have positive population-level impact (reduce disease burden in the community). It is shown that the BB phenomenon is caused by imperfect efficacy of the public health education program. The model is used to assess the potential impact of some targeted public health education campaigns using data from numerous countries. The second problem considered is a Susceptible-Infected-Removed (SIR) model with two types of nonlinear treatment rates: (i) piecewise linear treatment rate with saturation effect, (ii) piecewise constant treatment rate with a jump (Heaviside function). For Case (i), we construct travelling front solutions whose profiles are heteroclinic orbits which connect either the disease-free state to an infected state or two endemic states with each other. For Case (ii), it is shown that the profile has the following properties: the number of susceptible individuals is monotone increasing and the number of infectives approaches zero, while their product converges to a constant. Numerical simulations are shown which confirm these analytical results. Abnormal behavior like travelling waves with non-monotone profile or oscillations are observed.Kano State Government of Nigeri

Mathematical modelling and analysis of HIV transmission dynamics

This thesis firstly presents a nonlinear extended deterministic Susceptible-Infected (SI) model for assessing the impact of public health education campaign on curtailing the spread of the HIV pandemic in a population. Rigorous qualitative analysis of the model reveals that, in contrast to the model without education, the full model with education exhibits the phenomenon of backward bifurcation (BB), where a stable disease-free equilibrium coexists with a stable endemic equilibrium when a certain threshold quantity, known as the effective reproduction number (Reff ), is less than unity. Furthermore, an explicit threshold value is derived above which such an education campaign could lead to detrimental outcome (increase disease burden), and below which it would have positive population-level impact (reduce disease burden in the community). It is shown that the BB phenomenon is caused by imperfect efficacy of the public health education program. The model is used to assess the potential impact of some targeted public health education campaigns using data from numerous countries. The second problem considered is a Susceptible-Infected-Removed (SIR) model with two types of nonlinear treatment rates: (i) piecewise linear treatment rate with saturation effect, (ii) piecewise constant treatment rate with a jump (Heaviside function). For Case (i), we construct travelling front solutions whose profiles are heteroclinic orbits which connect either the disease-free state to an infected state or two endemic states with each other. For Case (ii), it is shown that the profile has the following properties: the number of susceptible individuals is monotone increasing and the number of infectives approaches zero, while their product converges to a constant. Numerical simulations are shown which confirm these analytical results. Abnormal behavior like travelling waves with non-monotone profile or oscillations are observed.EThOS - Electronic Theses Online ServiceKano State Government of NigeriaGBUnited Kingdo

Mathematical modelling and analysis of HIV transmission dynamics

This thesis firstly presents a nonlinear extended deterministic Susceptible-Infected (SI) model for assessing the impact of public health education campaign on curtailing the spread of the HIV pandemic in a population. Rigorous qualitative analysis of the model reveals that, in contrast to the model without education, the full model with education exhibits the phenomenon of backward bifurcation (BB), where a stable disease-free equilibrium coexists with a stable endemic equilibrium when a certain threshold quantity, known as the effective reproduction number (Reff ), is less than unity. Furthermore, an explicit threshold value is derived above which such an education campaign could lead to detrimental outcome (increase disease burden), and below which it would have positive population-level impact (reduce disease burden in the community). It is shown that the BB phenomenon is caused by imperfect efficacy of the public health education program. The model is used to assess the potential impact of some targeted public health education campaigns using data from numerous countries. The second problem considered is a Susceptible-Infected-Removed (SIR) model with two types of nonlinear treatment rates: (i) piecewise linear treatment rate with saturation effect, (ii) piecewise constant treatment rate with a jump (Heaviside function). For Case (i), we construct travelling front solutions whose profiles are heteroclinic orbits which connect either the disease-free state to an infected state or two endemic states with each other. For Case (ii), it is shown that the profile has the following properties: the number of susceptible individuals is monotone increasing and the number of infectives approaches zero, while their product converges to a constant. Numerical simulations are shown which confirm these analytical results. Abnormal behavior like travelling waves with non-monotone profile or oscillations are observed.EThOS - Electronic Theses Online ServiceKano State Government of NigeriaGBUnited Kingdo

Transmission dynamics of monkeypox virus in Nigeria during the current COVID-19 pandemic and estimation of effective reproduction number

Monkeypox virus (MPXV) continues to pose severe threats to global public health, especially in non-endemic areas. Like all other regions, Africa faces potential public health crises due to the ongoing COVID-19 pandemic and other infectious disease outbreaks (such as Lassa fever and malaria) that have devastated the region and overwhelmed the healthcare systems. Owing to the recent surge in the MPXV and other infections, the COVID-19-control efforts could deteriorate and further worsen. This study discusses the potential emergencies of MPXV transmission during the current COVID-19 pandemic. We hypothesize some of the underlying drivers that possibly resulted in an increase in rodent-to-human interaction, such as the COVID-19 pandemic’s impact and other human behavioral or environmental factors. Furthermore, we estimate the MPXV time-varying effective reproduction number ([Formula: see text]) based on case notification in Nigeria. We find that [Formula: see text] reached a peak in 2022 with a mean of 1.924 (95% CrI: 1.455, 2.485) and a median of 1.921 (95% CrI: 1.450, 2.482). We argue that the real-time monitoring of [Formula: see text] is practical and can give public health authorities crucial data for circumstantial awareness and strategy recalibration. We also emphasize the need to improve awareness programs and the provision of adequate health care resources to suppress the outbreaks. These could also help to increase the reporting rate and, in turn, prevent large community transmission of the MPXV in Nigeria and beyond

Mathematical analysis of a model for zoonotic visceral leishmaniasis

Zoonotic visceral leishmaniasis (ZVL), caused by the protozoan parasite Leishmania infantum and transmitted to humans and reservoir hosts by female sandflies, is endemic in many parts of the world (notably in Africa, Asia and the Mediterranean). This study presents a new mathematical model for assessing the transmission dynamics of ZVL in human and non-human animal reservoir populations. The model undergoes the usual phenomenon of backward bifurcation exhibited by similar vector-borne disease transmission models. In the absence of such phenomenon (which is shown to arise due to the disease-induced mortality in the host populations), the nontrivial disease-free equilibrium of the model is shown to be globally-asymptotically stable when the associated reproduction number of the model is less than unity. Using case and demographic data relevant to ZVL dynamics in Arac̣atuba municipality of Brazil, it is shown, for the default case when systemic insecticide-based drugs are not used to treat infected reservoir hosts, that the associated reproduction number of the model (ℛ0) ranges from 0.3 to 1.4, with a mean of ℛ0=0.85. Furthermore, when the effect of such drug treatment is explicitly incorporated in the model (i.e., accounting for the additional larval and sandfly mortality, following feeding on the treated reservoirs), the range of ℛ0 decreases to ℛ0∈[0.1,0.6], with a mean of ℛ0=0.35 (this significantly increases the prospect of the effective control or elimination of the disease). Thus, ZVL transmission models (in communities where such treatment strategy is implemented) that do not explicitly incorporate the effect of such treatment may be over-estimating the disease burden (as measured in terms of ℛ0) in the community. It is shown that ℛ0 is more sensitive to increases in sandfly lifespan than that of the animal reservoir (so, a strategy that focuses on reducing sandflies, rather than the animal reservoir (e.g., via culling), may be more effective in reducing ZVL burden in the community). Further sensitivity analysis of the model ranks the sandfly removal rate (by natural death or by feeding from insecticide-treated reservoir hosts), the biting rate of sandflies on the reservoir hosts and the progression rate of exposed reservoirs to active ZVL as the three parameters with the most effect on the disease dynamics or burden (as measured in terms of the reproduction number ℛ0). Hence, this study identifies the key parameters that play a key role on the disease dynamics, and thereby contributing in the design of effective control strategies (that target the identified parameters)

The Fallacy of a New Woman in Lola Shoneyi’s The Secret Lives of Baba Segi’s Wives

This paper explores the concept of “new woman” as conceived by Nigerian women writers through the lens of Akachi Adimora-Ezeigbo’s snail-sense feminism. Most feminists believe that a woman should be sophisticated, educated, and intelligent, and that she should be able to endure whatever tasks assigned to her at home and in her day-to-day activities, among other things. This idea stemmed from a desire to demonstrate to the world that a woman’s biological make-up should not be the sole criterion used to discriminate against other women in society. To demonstrate to readers that the entire notion of a “new woman” is nothing more than self-deception and a distorted version of the feminist struggle, the article examines Lola Shoneyi’s novel, The Secret Lives of Baba Segi’s Wives (2015). Shoneyi portrays Baba Segi’s four wives as clever and smart, even though the first three women, Iya Segi, Iya Tope, and Iya Femi, had no formal education. The novelty of this study is that it examines the concept of a new woman as a means of striking back at men who believe they are intellectually superior to women. Despite this, the author has been successful in ridiculing such egos by portraying the female characters as being smarter and more intelligent than the male characters. The finding of this research is that it demonstrates to readers that the issue of the “new woman” is to encourage escapades, as proclaimed by some feminists in most developing countries like Nigeria

Cohesive Energies Computation of BCC and FCC Crystals Using Density Functional Theory

The cohesive energies of BCC (Li, Cr, Fe, Mo), and FCC (LiCl, NaCl, RbBr, KI) solid crystals lattices have been calculated using density functional theory (DFT). DFT based Fritz Haber Institute-ab Initio molecular simulation (FHI-aims) computer code has several input parameters in which some of the variables were optimized. The cohesive energies of all the elements and compounds under study were calculated within Perdew Wang local density approximation (LDA) of DFT, all the results are in reasonable agreement with experimental measurements. The measurement of cohesive energy should give an idea about lattice interatomic spacing which in turn gives the stability of the crystal

Gross Alpha and Beta Radioactivity of Water from Gubi Dam Water Treatment Plant Gubi Village, Bauchi

In this research work, a total of 25 replicate samples from the study area comprising source water, treated water, as well as water from some boreholes around Gubi dam and Gubi water treatment plant, were collected for the analysis using Gas-flow Detector Dual Phosphor (counting system) method to determine the gross alpha and beta concentrations. The results showed that the values for the gross alpha and beta measurements were found to be (7.057E-03Bq/ m3 ), ( 1.0253E-02 Bq/ m3) and (2.693E-02 Bq/ m3) for samples from the dam, treated water and the borehole respectively. Furthermore, the mean concentrations were also determined to be (4.11E-02Bq/ m3), (3.74E-02Bq/ m3) and (1.0756E-01Bq/ m3). The study revealed that water from Gubi dam whether treated, untreated or groundwater around the dam purses no radiological hazards for agricultural and other domestic uses