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Presented is a study on the chemotaxis reaction process and its relation with flow topology. The effect of coherent structures in turbulent flows is characterized by studying nutrient uptake and the advantage that is received from motile bacteria over other non-motile bacteria. Variability is found to be dependent on the initial location of scalar impurity and can be tied to Lagrangian coherent structures through recent advances in the identification of finite-time transport barriers. Advantage is relatively small for initial nutrient found within high stretching regions of the flow, and nutrient within elliptic structures provide the greatest advantage for motile species. How the flow field and the relevant flow topology lead to such a relation is analyzed.
ContributorsJones, Kimberly (Author) / Tang, Wenbo (Thesis advisor) / Kang, Yun (Committee member) / Jones, Donald (Committee member) / Arizona State University (Publisher)
Created2015
Description
In this dissertation the potential impact of some social, cultural and economic factors on
Ebola Virus Disease (EVD) dynamics and control are studied. In Chapter two, the inability
to detect and isolate a large fraction of EVD-infected individuals before symptoms onset is
addressed. A mathematical model, calibrated with data from the 2014 West African outbreak,
is used to show the dynamics of EVD control under various quarantine and isolation
effectiveness regimes. It is shown that in order to make a difference it must reach a high
proportion of the infected population. The effect of EVD-dead bodies has been incorporated
in the quarantine effectiveness. In Chapter four, the potential impact of differential
risk is assessed. A two-patch model without explicitly incorporate quarantine is used to
assess the impact of mobility on communities at risk of EVD. It is shown that the
overall EVD burden may lessen when mobility in this artificial high-low risk society is allowed.
The cost that individuals in the low-risk patch must pay, as measured by secondary
cases is highlighted. In Chapter five a model explicitly incorporating patch-specific quarantine
levels is used to show that quarantine a large enough proportion of the population
under effective isolation leads to a measurable reduction of secondary cases in the presence
of mobility. It is shown that sharing limited resources can improve the effectiveness of
EVD effective control in the two-patch high-low risk system. Identifying the conditions
under which the low-risk community would be willing to accept the increases in EVD risk,
needed to reduce the total number of secondary cases in a community composed of two
patches with highly differentiated risks has not been addressed. In summary, this dissertation
looks at EVD dynamics within an idealized highly polarized world where resources
are primarily in the hands of a low-risk community – a community of lower density, higher
levels of education and reasonable health services – that shares a “border” with a high-risk
community that lacks minimal resources to survive an EVD outbreak.
Ebola Virus Disease (EVD) dynamics and control are studied. In Chapter two, the inability
to detect and isolate a large fraction of EVD-infected individuals before symptoms onset is
addressed. A mathematical model, calibrated with data from the 2014 West African outbreak,
is used to show the dynamics of EVD control under various quarantine and isolation
effectiveness regimes. It is shown that in order to make a difference it must reach a high
proportion of the infected population. The effect of EVD-dead bodies has been incorporated
in the quarantine effectiveness. In Chapter four, the potential impact of differential
risk is assessed. A two-patch model without explicitly incorporate quarantine is used to
assess the impact of mobility on communities at risk of EVD. It is shown that the
overall EVD burden may lessen when mobility in this artificial high-low risk society is allowed.
The cost that individuals in the low-risk patch must pay, as measured by secondary
cases is highlighted. In Chapter five a model explicitly incorporating patch-specific quarantine
levels is used to show that quarantine a large enough proportion of the population
under effective isolation leads to a measurable reduction of secondary cases in the presence
of mobility. It is shown that sharing limited resources can improve the effectiveness of
EVD effective control in the two-patch high-low risk system. Identifying the conditions
under which the low-risk community would be willing to accept the increases in EVD risk,
needed to reduce the total number of secondary cases in a community composed of two
patches with highly differentiated risks has not been addressed. In summary, this dissertation
looks at EVD dynamics within an idealized highly polarized world where resources
are primarily in the hands of a low-risk community – a community of lower density, higher
levels of education and reasonable health services – that shares a “border” with a high-risk
community that lacks minimal resources to survive an EVD outbreak.
ContributorsEspinoza Cortes, Baltazar (Author) / Castillo-Chavez, Carlos (Thesis advisor) / Kang, Yun (Committee member) / Safan, Muntaser (Committee member) / Arizona State University (Publisher)
Created2018
Description
The dissertation addresses questions tied in to the challenges posed by the impact of environmental factors on the nonlinear dynamics of social upward mobility. The proportion of educated individuals from various socio-economic backgrounds is used as a proxy for the environmental impact on the status quo state.
Chapter 1 carries out a review of the mobility models found in the literature and sets the economic context of this dissertation. Chapter 2 explores a simple model that considers poor and rich classes and the impact that educational success may have on altering mobility patterns. The role of the environment is modeled through the use of a modified version of the invasion/extinction model of Richard Levins. Chapter 3 expands the socio-economic classes to include a large middle class to study the role of social mobility in the presence of higher heterogeneity. Chapter 4 includes demographic growth and explores what would be the time scales needed to accelerate mobility. The dissertation asked how long it will take to increase by 22% the proportion of educated from the poor classes under demographic versus non-demographic growth conditions. Chapter 5 summarizes results and includes a discussion of results. It also explores ways of modeling the influence of nonlinear dynamics of mobility, via exogenous factors. Finally, Chapter 6 presents economic perspectives about the role of environmental influence on college success. The framework can be used to incorporate the impact of economic factors and social changes, such as unemployment, or gap between the haves and have nots. The dissertation shows that peer influence (poor influencing the poor) has a larger effect than class influence (rich influencing the poor). Additionally, more heterogeneity may ease mobility of groups but results depend on initial conditions. Finally, average well-being of the community and income disparities may improve over time. Finally, population growth may extend time scales needed to achieve a specific goal of educated poor.
Chapter 1 carries out a review of the mobility models found in the literature and sets the economic context of this dissertation. Chapter 2 explores a simple model that considers poor and rich classes and the impact that educational success may have on altering mobility patterns. The role of the environment is modeled through the use of a modified version of the invasion/extinction model of Richard Levins. Chapter 3 expands the socio-economic classes to include a large middle class to study the role of social mobility in the presence of higher heterogeneity. Chapter 4 includes demographic growth and explores what would be the time scales needed to accelerate mobility. The dissertation asked how long it will take to increase by 22% the proportion of educated from the poor classes under demographic versus non-demographic growth conditions. Chapter 5 summarizes results and includes a discussion of results. It also explores ways of modeling the influence of nonlinear dynamics of mobility, via exogenous factors. Finally, Chapter 6 presents economic perspectives about the role of environmental influence on college success. The framework can be used to incorporate the impact of economic factors and social changes, such as unemployment, or gap between the haves and have nots. The dissertation shows that peer influence (poor influencing the poor) has a larger effect than class influence (rich influencing the poor). Additionally, more heterogeneity may ease mobility of groups but results depend on initial conditions. Finally, average well-being of the community and income disparities may improve over time. Finally, population growth may extend time scales needed to achieve a specific goal of educated poor.
ContributorsMontalvo, Cesar Paul (Author) / Castillo-Chavez, Carlos (Thesis advisor) / Mubayi, Anuj (Thesis advisor) / Perrings, Charles (Committee member) / Kang, Yun (Committee member) / Arizona State University (Publisher)
Created2020