Matching Items (114)
Description
Rabies disease remains enzootic among raccoons, skunks, foxes and bats in the United States. It is of primary concern for public-health agencies to control spatial spread of rabies in wildlife and its potential spillover infection of domestic animals and humans. Rabies is invariably fatal in wildlife if untreated, with a non-negligible incubation period. Understanding how this latency affects spatial spread of rabies in wildlife is the concern of chapter 2 and 3. Chapter 1 deals with the background of mathematical models for rabies and lists main objectives. In chapter 2, a reaction-diffusion susceptible-exposed-infected (SEI) model and a delayed diffusive susceptible-infected (SI) model are constructed to describe the same epidemic process -- rabies spread in foxes. For the delayed diffusive model a non-local infection term with delay is resulted from modeling the dispersal during incubation stage. Comparison is made regarding minimum traveling wave speeds of the two models, which are verified using numerical experiments. In chapter 3, starting with two Kermack and McKendrick's models where infectivity, death rate and diffusion rate of infected individuals can depend on the age of infection, the asymptotic speed of spread $c^\ast$ for the cumulated force of infection can be analyzed. For the special case of fixed incubation period, the asymptotic speed of spread is governed by the same integral equation for both models. Although explicit solutions for $c^\ast$ are difficult to obtain, assuming that diffusion coefficient of incubating animals is small, $c^\ast$ can be estimated in terms of model parameter values. Chapter 4 considers the implementation of realistic landscape in simulation of rabies spread in skunks and bats in northeast Texas. The Finite Element Method (FEM) is adopted because the irregular shapes of realistic landscape naturally lead to unstructured grids in the spatial domain. This implementation leads to a more accurate description of skunk rabies cases distributions.
ContributorsLiu, Hao (Author) / Kuang, Yang (Thesis advisor) / Jackiewicz, Zdzislaw (Committee member) / Lanchier, Nicolas (Committee member) / Smith, Hal (Committee member) / Thieme, Horst (Committee member) / Arizona State University (Publisher)
Created2013
Description
Bacteriophage (phage) are viruses that infect bacteria. Typical laboratory experiments show that in a chemostat containing phage and susceptible bacteria species, a mutant bacteria species will evolve. This mutant species is usually resistant to the phage infection and less competitive compared to the susceptible bacteria species. In some experiments, both susceptible and resistant bacteria species, as well as phage, can coexist at an equilibrium for hundreds of hours. The current research is inspired by these observations, and the goal is to establish a mathematical model and explore sufficient and necessary conditions for the coexistence. In this dissertation a model with infinite distributed delay terms based on some existing work is established. A rigorous analysis of the well-posedness of this model is provided, and it is proved that the susceptible bacteria persist. To study the persistence of phage species, a "Phage Reproduction Number" (PRN) is defined. The mathematical analysis shows phage persist if PRN > 1 and vanish if PRN < 1. A sufficient condition and a necessary condition for persistence of resistant bacteria are given. The persistence of the phage is essential for the persistence of resistant bacteria. Also, the resistant bacteria persist if its fitness is the same as the susceptible bacteria and if PRN > 1. A special case of the general model leads to a system of ordinary differential equations, for which numerical simulation results are presented.
ContributorsHan, Zhun (Author) / Smith, Hal (Thesis advisor) / Armbruster, Dieter (Committee member) / Kawski, Matthias (Committee member) / Kuang, Yang (Committee member) / Thieme, Horst (Committee member) / Arizona State University (Publisher)
Created2012
Description
In vertebrate outer retina, changes in the membrane potential of horizontal cells affect the calcium influx and glutamate release of cone photoreceptors via a negative feedback. This feedback has a number of important physiological consequences. One is called background-induced flicker enhancement (BIFE) in which the onset of dim background enhances the center flicker response of horizontal cells. The underlying mechanism for the feedback is still unclear but competing hypotheses have been proposed. One is the GABA hypothesis, which states that the feedback is mediated by gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter released from horizontal cells. Another is the ephaptic hypothesis, which contends that the feedback is non-GABAergic and is achieved through the modulation of electrical potential in the intersynaptic cleft between cones and horizontal cells. In this study, a continuum spine model of the cone-horizontal cell synaptic circuitry is formulated. This model, a partial differential equation system, incorporates both the GABA and ephaptic feedback mechanisms. Simulation results, in comparison with experiments, indicate that the ephaptic mechanism is necessary in order for the model to capture the major spatial and temporal dynamics of the BIFE effect. In addition, simulations indicate that the GABA mechanism may play some minor modulation role.
ContributorsChang, Shaojie (Author) / Baer, Steven M. (Thesis advisor) / Gardner, Carl L (Thesis advisor) / Crook, Sharon M (Committee member) / Kuang, Yang (Committee member) / Ringhofer, Christian (Committee member) / Arizona State University (Publisher)
Created2012
Description
Cancer remains one of the leading killers throughout the world. Death and disability due to lung cancer in particular accounts for one of the largest global economic burdens a disease presents. The burden on third-world countries is especially large due to the unusually large financial stress that comes from late tumor detection and expensive treatment options. Early detection using inexpensive techniques may relieve much of the burden throughout the world, not just in more developed countries. I examined the immune responses of lung cancer patients using immunosignatures – patterns of reactivity between host serum antibodies and random peptides. Immunosignatures reveal disease-specific patterns that are very reproducible. Immunosignaturing is a chip-based method that has the ability to display the antibody diversity from individual sera sample with low cost. Immunosignaturing is a medical diagnostic test that has many applications in current medical research and in diagnosis. From a previous clinical study, patients diagnosed for lung cancer were tested for their immunosignature vs. healthy non-cancer volunteers. The pattern of reactivity against the random peptides (the ‘immunosignature’) revealed common signals in cancer patients, absent from healthy controls. My study involved the search for common amino acid motifs in the cancer-specific peptides. My search through the hundreds of ‘hits’ revealed certain motifs that were repeated more times than expected by random chance. The amino acids that were the most conserved in each set include tryptophan, aspartic acid, glutamic acid, proline, alanine, serine, and lysine. The most overall conserved amino acid observed between each set was D - aspartic acid. The motifs were short (no more than 5-6 amino acids in a row), but the total number of motifs I identified was large enough to assure significance. I utilized Excel to organize the large peptide sequence libraries, then CLUSTALW to cluster similar-sequence peptides, then GLAM2 to find common themes in groups of peptides. In so doing, I found sequences that were also present in translated cancer expression libraries (RNA) that matched my motifs, suggesting that immunosignatures can find cancer-specific antigens that can be both diagnostic and potentially therapeutic.
ContributorsShiehzadegan, Shima (Author) / Johnston, Stephen (Thesis director) / Stafford, Phillip (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2015-12
Description
This paper features analysis of interdisciplinary collaboration, based on the results from the Kolbe A™ Index of students in the Nano Ethics at Play (NEAP) class, a four week course in Spring 2015. The Kolbe A™ is a system which describes the Conative Strengths of each student, or their natural drive and instinct. NEAP utilized the LEGO® SERIOUS PLAY® (LSP) method, which uses abstract LEGO models to describe answers to a proposed question in school or work environments. The models could be described piece by piece to provide clear explanations without allowing disciplinary jargon, which is why the class contained students from eleven different majors (Engineering (Civil, Biomedical, & Electrical), Business (Marketing & Supply Chain Management), Architectural Studies, Sustainability, Anthropology, Communications, Philosophy, & Psychology).
The proposed hypotheses was based on the four different Kolbe A™ strengths, or Action Modes: Fact Finder, Follow Through, Quick Start, and Implementor. Hypotheses were made about class participation and official class twitter use, using #ASUsp, for each Kolbe type. The results proved these hypotheses incorrect, indicating a lack of correlation between Kolbe A™ types and playing. The report also includes qualitative results such as Twitter Keywords and a Sentiment calculation for each week of the course. The class had many positive outcomes, including growth in the ability to collaborate by students, further understanding of how to integrate Twitter use into the classroom, and more knowledge about the effectiveness of LSP.
The proposed hypotheses was based on the four different Kolbe A™ strengths, or Action Modes: Fact Finder, Follow Through, Quick Start, and Implementor. Hypotheses were made about class participation and official class twitter use, using #ASUsp, for each Kolbe type. The results proved these hypotheses incorrect, indicating a lack of correlation between Kolbe A™ types and playing. The report also includes qualitative results such as Twitter Keywords and a Sentiment calculation for each week of the course. The class had many positive outcomes, including growth in the ability to collaborate by students, further understanding of how to integrate Twitter use into the classroom, and more knowledge about the effectiveness of LSP.
ContributorsStevens, Jenna Marie (Author) / Seager, Thomas (Thesis director) / Jenses, Camilla (Committee member) / Civil, Environmental and Sustainable Engineering Programs (Contributor) / Herberger Institute for Design and the Arts (Contributor) / Barrett, The Honors College (Contributor)
Created2015-12
Description
One of the salient challenges of sustainability is the Tragedy of the Commons, where individuals acting independently and rationally deplete a common resource despite their understanding that it is not in the group's long term best interest to do so. Hardin presents this dilemma as nearly intractable and solvable only by drastic, government-mandated social reforms, while Ostrom's empirical work demonstrates that community-scale collaboration can circumvent tragedy without any elaborate outside intervention. Though more optimistic, Ostrom's work provides scant insight into larger-scale dilemmas such as climate change. Consequently, it remains unclear if the sustainable management of global resources is possible without significant government mediation. To investigate, we conducted two game theoretic experiments that challenged students in different countries to collaborate digitally and manage a hypothetical common resource. One experiment involved students attending Arizona State University and the Rochester Institute of Technology in the US and Mountains of the Moon University in Uganda, while the other included students at Arizona State and the Management Development Institute in India. In both experiments, students were randomly assigned to one of three production roles: Luxury, Intermediate, and Subsistence. Students then made individual decisions about how many units of goods they wished to produce up to a set maximum per production class. Luxury players gain the most profit (i.e. grade points) per unit produced, but they also emit the most externalities, or social costs, which directly subtract from the profit of everybody else in the game; Intermediate players produce a medium amount of profit and externalities per unit, and Subsistence players produce a low amount of profit and externalities per unit. Variables influencing and/or inhibiting collaboration were studied using pre- and post-game surveys. This research sought to answer three questions: 1) Are international groups capable of self-organizing in a way that promotes sustainable resource management?, 2) What are the key factors that inhibit or foster collective action among international groups?, and 3) How well do Hardin's theories and Ostrom's empirical models predict the observed behavior of students in the game? The results of gameplay suggest that international cooperation is possible, though likely sub-optimal. Statistical analysis of survey data revealed that heterogeneity and levels of trust significantly influenced game behavior. Specific traits of heterogeneity among students found to be significant were income, education, assigned production role, number of people in one's household, college class, college major, and military service. Additionally, it was found that Ostrom's collective action framework was a better predictor of game outcome than Hardin's theories. Overall, this research lends credence to the plausibility of international cooperation in tragedy of the commons scenarios such as climate change, though much work remains to be done.
ContributorsStanton, Albert Grayson (Author) / Clark, Susan Spierre (Thesis director) / Seager, Thomas (Committee member) / Civil, Environmental and Sustainable Engineering Programs (Contributor) / Barrett, The Honors College (Contributor)
Created2014-12
Description
While public transit systems are perceived to produce lower GHG emission intensities per passenger miles traveled (PMT) and per vehicle miles traveled (VMT), there is a limited understanding of emissions per PMT/VMT across cities, or of how emissions may change across modes (light, metro, commuter, and bus) and time (e.g., with changing electricity mixes in the future). In order to better understand the GHG emissions intensity of public transit systems, a comparative emissions assessment was developed utilizing the National Transit Database (NTD) which reports energy use from 1997 to 2012 of rail and bus systems across the US. By determining the GHG emission intensities (per VMT or per PMT) for each mode of transit across multiple years, the modes of transit can be better compared between one another. This comparison can help inform future goals to reduce GHG emissions as well as target reductions from the mode of transit that has the highest emissions. The proposed analysis of the NTD and comparison of modal emission intensities will be used to develop future forecasting that can guide public transit systems towards a sustainable future.
ContributorsCano, Alex (Author) / Chester, Mikhail (Thesis director) / Seager, Thomas (Committee member) / Civil, Environmental and Sustainable Engineering Programs (Contributor) / Barrett, The Honors College (Contributor) / School of Sustainability (Contributor) / School of Human Evolution and Social Change (Contributor)
Created2014-12
Description
The influenza virus, also known as "the flu", is an infectious disease that has constantly affected the health of humanity. There is currently no known cure for Influenza. The Center for Innovations in Medicine at the Biodesign Institute located on campus at Arizona State University has been developing synbodies as a possible Influenza therapeutic. Specifically, at CIM, we have attempted to design these initial synbodies to target the entire Influenza virus and preliminary data leads us to believe that these synbodies target Nucleoprotein (NP). Given that the synbody targets NP, the penetration of cells via synbody should also occur. Then by Western Blot analysis we evaluated for the diminution of NP level in treated cells versus untreated cells. The focus of my honors thesis is to explore how synthetic antibodies can potentially inhibit replication of the Influenza (H1N1) A/Puerto Rico/8/34 strain so that a therapeutic can be developed. A high affinity synbody for Influenza can be utilized to test for inhibition of Influenza as shown by preliminary data. The 5-5-3819 synthetic antibody's internalization in live cells was visualized with Madin-Darby Kidney Cells under a Confocal Microscope. Then by Western Blot analysis we evaluated for the diminution of NP level in treated cells versus untreated cells. Expression of NP over 8 hours time was analyzed via Western Blot Analysis, which showed NP accumulation was retarded in synbody treated cells. The data obtained from my honors thesis and preliminary data provided suggest that the synthetic antibody penetrates live cells and targets NP. The results of my thesis presents valuable information that can be utilized by other researchers so that future experiments can be performed, eventually leading to the creation of a more effective therapeutic for influenza.
ContributorsHayden, Joel James (Author) / Diehnelt, Chris (Thesis director) / Johnston, Stephen (Committee member) / Legutki, Bart (Committee member) / Barrett, The Honors College (Contributor) / Department of Psychology (Contributor) / Department of Chemistry and Biochemistry (Contributor)
Created2014-05
Description
Life cycle assessment (LCA) is increasingly identified as the proper tool/framework for performing cradle to grave analysis of a product, technology, or supply chain. LCA proceeds by comparing the materials and energy needed for materials extraction, benefaction, and end-of-life management, in addition to the actual lifetime of the product. This type of analysis is commonly used to evaluate forms of renewable energy to ensure that we don't harm the environment in the name of saving it. For instance, LCA for photovoltaic (PV) technologies can be used to evaluate the environmental impacts. CdTe thin film solar cells rely on cadmium and tellurium metals which are produced as by-products in the refining of zinc and copper ore, respectively. In order to understand the environmental burdens of tellurium, it is useful to explore the extraction and refining process of copper. Copper can be refined using either a hydrometallurgical or pyrometallurgical process. I conducted a comparison of these two methods to determine the environmental impacts, the chemical reactions which take place, the energy requirements, and the extraction costs of each. I then looked into the extraction of tellurium from anode slime produced in the pyrometallurgical process and determined the energy requirements. I connected this to the production of CdTe and the power produced from a CdTe module, and analyzed the production cost of CdTe modules under increasing tellurium prices. It was concluded that tellurium production will be limited by increasing hydrometallurgical extraction of copper. Additionally, tellurium scarcity will not provide a physical constraint to CdTe commercial expansion; however it could affect the price reduction goals.
ContributorsMacIsaac, Kirsten Breanne (Author) / Seager, Thomas (Thesis director) / Fraser, Matthew (Committee member) / Wender, Ben (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2013-05
Description
Team dynamics: a system of behaviors and psychological processes occurring within a social group (wiki). This definition classifies it as pertaining to a social group, so how do team dynamics vary from one specific social group to another? Social groups are created for many different reasons, some inherent (such as families) and some created intentionally with knowledge of what is being done (such as athletic teams, class project groups, and groups in the workforce). The way these groups interact and work as a team shapes how efficient they can work and how well they are able to achieve set goals. Therefore, in order to predict how well a particular group or team might perform in a routine project, it is useful to analyze the way they work together on a regular basis. Certain aspects of different groups, such as gender, age, level of competition, and type of activity, cause them to work together in different manners. Do any of these factors cause a particular group to work better as a team? Or do they just cause them to work differently?
ContributorsDunn, Travis Griffin (Author) / Lawrence, Christopher (Thesis director) / Seager, Thomas (Committee member) / Weaver, Edwin (Committee member) / Civil, Environmental and Sustainable Engineering Programs (Contributor) / Barrett, The Honors College (Contributor)
Created2013-05