1,720,970 research outputs found
Mathematical models for the dynamics of health related risks associated with alcoholism and its control strategy in Tanzania
Full text linkA Thesis Submitted in Fulfilment of the Requirements for the Degree of PhD Degree in
Mathematical and Computer Science and Engineering of the Nelson Mandela African
Institution of Science and TechnologyAlcoholic behavior has continually posed health challenges in many communities for decades.
Referring to Tanzanian situation, this study presents a more realistic model for the dynamics of
health risks associated with alcoholism. The model considered a population proportion that has
social cultural protection from alcohol consumption. In the context of this study, such protec tion emanated from religious beliefs practiced in the country. Three versions of the model were
analyzed considering different model analysis scenarios: the basic model, fuzzy logic model,
and optimal control model. The equilibria of the basic model were obtained and their stability
analysis was performed. The Next Generation Matrix (NGM) approach was used to compute
the basic risk reproduction number of the basic model. The risk free equilibrium point of the ba sic model was proved to be globally asymptotically stable whenever the basic risk reproduction
ratio was less than unit and unstable otherwise. The sensitivity analysis of the basic risk repro duction number of the basic model and numerical simulation were carried out. Their results
revealed that deliberate intervention strategies and policies focused on discouraging alcoholic
behaviors on their onset during initiation stage were more effective than dealing with alcoholic
population proportions. The fuzzy logic based model analysis have confirmed this result where
uncertainty conditions were assumed in the measure of influence of alcoholic individua
The randomness and uncertainty in dynamics of lymphatic filariasis: CTMC stochastic approach
Full text linkThis Research Article was published by the The European Physical Journal Plus:Volume 139, article number 162, (2024)Lymphatic filariasis represents the primary cause of long-term, permanent disability, and dysfunction in the human immune system. In this study, we have devised and assessed deterministic and continuous-time Markov chain (CTMC) stochastic models to gain insights into the dynamics of lymphatic filariasis and approximate the probabilities of disease extinction or outbreak. The CTMC stochastic model is an adapted version of the existing deterministic model that accounts for uncertainties and variations in disease transmission dynamics. The findings from the deterministic model indicate that disease extinction is possible when , while an outbreak is likely when . Further examination of the deterministic model emphasizes the significant role of asymptomatic individuals in the transmission of lymphatic filariasis. To estimate the probabilities of disease extinction or outbreak, we employed multitype branching processes and numerical simulations. The results demonstrate that lymphatic filariasis outbreaks are more probable when microfilariae parasites are introduced by exposed humans, asymptomatic humans, acutely infected humans, exposed mosquitoes, or infectious mosquitoes. Conversely, the disease is more likely to be eradicated if it originates from chronically infected humans. Utilizing stochastic methods provides a more authentic portrayal of how lymphatic filariasis spreads, granting a better understanding of the spectrum of potential results and their related probabilities. Therefore, stochastic CTMC models become indispensable for generating reliable forecasts and well-informed choices in situations where deterministic models might oversimplify or inaccurately depict the inherent unpredictability
The Volterra–Lyapunov matrix theory for global stability analysis of alcohol-related health risks model
Full text linkThis paper studies the global stability analysis of a modified framework proposed by Mayengo et al. on alcohol-related health risks model. We first present the global stability analysis of risk-free equilibrium (RFE). Later, the global stability of the risk endemic equilibrium is studied. This goal was achieved by appropriate utilization of the symmetrical properties in the structure of Volterra–Lyapunov matrices. The analysis and results presented in this paper make building blocks towards a comprehensive study and deeper understanding of the fundamental mechanism in alcohol-related health risks and similar models. The numerical examples are simulated to validate the theoretical model results presented
Parameters estimation, global sensitivity analysis and model fitting for the dynamics of Plutella xylostella infestations in a cabbage biomass
Full text linkThis research article was published by Chaos, Solitons & Fractals: X,Volume 12, 2024Plutella xylostella, commonly called Diamondback moth (DBM), a highly destructive and rapidly spreading
agricultural pest originally from Europe. This pest poses a significant threat to global food security, with estimates
suggesting that periodic outbreaks of Diamondback moth lead to annual crop losses of up to $US 4 − 5 billion
worldwide. Given the potential for such substantial losses, it is crucial to employ various methods and techniques
to understand the factors affecting the interaction between Diamondback moths and cabbage plants, which,
in turn, impact cabbage biomass. In this paper, we propose a deterministic ecological model to capture the
dynamics of Plutella xylostella infestations in cabbage biomass. The model is designed based on the life cycle
stages of the pest, aiming at targeting the specific stage effectively. The synthetic data is generated using Least
Square Algorithm through addition of Gaussian noise into numerically obtained values from existing literature
to simulate real-world data. Global sensitivity analysis was done through Latin Hypercube sampling, highlights
the significance of parameters such as , and positively influence the growth of the diamondback moth in
a cabbage biomass. In light of these findings, the study proposes that control strategies should be specifically
directed towards these sensitive parameters. By doing so, we mitigate the pest population and enhance cabbage
production
Modeling Health Risks Associated with Second-hand Tobacco Smoke Exposure: NIL
No full textA non-smoker who is exposed to second-hand tobacco smoke is in danger of suffering from diseases such as coronary heart disease, asthma attacks, stroke and lung cancer. This exposure occurs in various set tings, including living with smokers at home, visiting bars and casinos, public places, and transport vehicles. Additionally, individuals exposed to second-hand tobacco smoke may experience severe health risks includ ing deaths. To gain insights about the dynamics of second-hand tobacco smoke exposure and its associated health risks to non-smokers, a deterministic mathematical model is developed and analysed. Such a model is developed by using non-linear first order ordinary differential equations and the analysis was carried out ana lytically and numerically. Numerical simulation results in this study confirm that, 90% increase in interaction between smokers and non-smokers can increase health risks to non-smokers by 7%. Additionally, the formu lated system exhibits backward bifurcation implying the possibility of having large outbreaks of health risks related to second-hand tobacco smoke even in communities with a relatively small number of smokers. The study underscores the importance of interventions to mitigate the health risks associated with second-hand tobacco smoke. Specifically, efforts should focus on reducing interactions between smokers and non-smokers during smoking or providing robust support mechanisms to help smokers quit
The role of asymptomatic carriers on the dynamics of a lymphatic filariasis model incorporating control strategies
Full text linkThis Research Article was published by the Results in Control and Optimization
Volume 15, 2024This study presents a mathematical model to investigate the patterns of transmission in lymphatic filariasis. The model considers chronic, acute, and asymptomatic individuals and integrates key control strategies. Random synthetic data is generated robustly through numerical solutions to closely replicate real-world scenarios and encompass uncertainties. The synthetic data adheres to a Gaussian distribution to ensure validity and reliability. Following the derivation of the basic and effective reproduction number using the next generation matrix approach, Latin Hypercube Sampling (LHS) and the Partial Rank Correlation Coefficient (PRCC) algorithm is utilized to assess the parameters that significantly influence the model outputs. The study examine the trajectories of different population compartments through numerical simulations over time, with particular emphasis on the role played by asymptomatic individuals in the transmission of the disease. To assess the potential for disease elimination, the study introduces a range of strategies involving protective measures, treatment interventions, and mosquito control. These strategies are determined through sensitivity analysis. The findings demonstrate that the simultaneous implementation of all control measures has a noteworthy effect in managing lymphatic filariasis. In conclusion, the proposed model enhances understanding of lymphatic filariasis dynamics and informs effective control strategies
Mathematical modeling of vehicle carbon dioxide emissions
Full text linkThis research article was published in the Heliyon, 2024The demand for transportation, driven by an increasing global population, is continuously rising.
This has led to a higher number of vehicles on the road and an increased reliance on fossil
fuels. Consequently, the rise in atmospheric carbon dioxide (2) levels has contributed to
global warming. Therefore, it is important to consider sustainable transportation practices to
meet climate change mitigation targets. In this research paper, a non-linear mathematical model
is developed to study the dynamics of atmospheric 2 concentration in relation to human
population, economic activities, forest biomass, and vehicle population. The developed model
is analyzed qualitatively to understand the long-term behavior of the system’s dynamics. Model
parameters are fitted to actual data of world population, human economic activities, atmospheric
2, forest biomass, and vehicle population. It is shown that increased vehicular 2 emissions
have a potential contribution to the increase in atmospheric 2 and the decline of human
population. Numerical simulations are carried out to verify the analytical findings and we
performed global sensitivity analysis to explore the impacts of different sensitive parameters on
the 2 dynamics
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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