Matching Items (578)
Filtering by

Clear all filters

150637-Thumbnail Image.png
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

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
150711-Thumbnail Image.png
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

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
148189-Thumbnail Image.png
Description

This study was conducted to determine the difference in compressive strength between decayed and healthy teeth. The teeth were subjected to a compressive force to simulate the process of mastication. This was done to show that healthy teeth would be better at handling these compressive forces since they have more

This study was conducted to determine the difference in compressive strength between decayed and healthy teeth. The teeth were subjected to a compressive force to simulate the process of mastication. This was done to show that healthy teeth would be better at handling these compressive forces since they have more enamel. 26 teeth samples were collected (19 molars, 4 canines, and 3 premolars) evenly distributed between healthy and decayed. The samples were dimensionally analyzed using electronic calipers and then categorized as either decayed or healthy. The samples were then placed in a nut bolt with epoxy so that the samples could be compressed. Each sample was recorded on video while they were being exposed to the compressive force. This was done to observe how the samples were coming in contact with the Shimadzu compression machine. The amount of force that was required for the samples to exhibit the first point of breakage was recorded by the machine in pounds of force. Various analyses were conducted to determine relationships between several variables. The results showed that as the total and occlusal surface area increased, so did the amount of force the samples could absorb before breakage. As the machine came in contact with more cusps among the molar samples, those samples were able to absorb a larger compressive force. The average force that the decayed and healthy molar samples endured before breakage was roughly even, with the decayed samples average being slightly greater.

ContributorsHenscheid, Keaton J (Author) / Quaranta, Kimberly (Thesis director) / Peoples, Samuel (Committee member) / College of Health Solutions (Contributor) / Dean, W.P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
148321-Thumbnail Image.png
Description

This study examines the effectiveness of two modes of exercise on inhibitory control in adults with Down Syndrome (DS). Thirteen participants attended four sessions: a baseline assessment, an Assisted Cycling Therapy (ACT) session, a Resistance Training (RT) session, and a session of No Training (NT). In the baseline assessment, 1-repetition

This study examines the effectiveness of two modes of exercise on inhibitory control in adults with Down Syndrome (DS). Thirteen participants attended four sessions: a baseline assessment, an Assisted Cycling Therapy (ACT) session, a Resistance Training (RT) session, and a session of No Training (NT). In the baseline assessment, 1-repetition max (1RM) measurements and voluntary pedal rate measurements were taken. In the resistance training session, the leg press, chest press, seated row, leg curl, shoulder press, and latissimus pulldown were performed. In the cycling intervention, the participant completed 30 minutes of cycling. The Erikson Flanker task was administered prior to each session (i.e., pretest) and after the intervention (i.e., post-test). The results were somewhat consistent with the hypothesis that inhibition time improved more following RT and ACT than NT. there was also a significant difference between ACT and NT. Additionally, it was hypothesized that all measures would improve following each acute exercise intervention, but the most significant improvements were seen following ACT. In conclusion, an acute session of ACT demonstrated a significant trend towards improvements in inhibitory control in adults with DS which we interpreted using a model of neural changes.

ContributorsHayes, Claire (Author) / Ringenbach, Shannon (Thesis director) / Arnold, Nate (Committee member) / Rand, Miya (Committee member) / Edson College of Nursing and Health Innovation (Contributor) / College of Health Solutions (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
148324-Thumbnail Image.png
Description

The various health benefits of vinegar ingestion have been studied extensively in the<br/>literature. Moreover, emerging research suggests vinegar may also have an effect on mental<br/>health. Beneficial effects of certain diets on mood have been reported, however, the mechanisms<br/>are unknown. The current study aimed to determine if vinegar ingestion positively affects

The various health benefits of vinegar ingestion have been studied extensively in the<br/>literature. Moreover, emerging research suggests vinegar may also have an effect on mental<br/>health. Beneficial effects of certain diets on mood have been reported, however, the mechanisms<br/>are unknown. The current study aimed to determine if vinegar ingestion positively affects mood<br/>state in healthy young adults. This was a randomized, single blinded controlled trial consisting of<br/>25 subjects. Participants were randomly assigned to either the vinegar group (consumed 2<br/>tablespoons of liquid vinegar diluted in one cup water twice daily with meals) or the control<br/>group (consumed one vinegar pill daily with a meal), and the intervention lasted 4 weeks.<br/>Subjects completed mood questionnaires pre- and post-intervention. Results showed a significant<br/>improvement in CES-D and POMS-Depression scores for the vinegar group compared to the<br/>control. This study suggests that vinegar ingestion may improve depressive symptoms in healthy<br/>young adults.

ContributorsWilliams, Susanna (Author) / Johnston, Carol (Thesis director) / Whisner, Corrie (Committee member) / College of Health Solutions (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
137816-Thumbnail Image.png
Description
Childhood obesity is a growing public health concern in the United States. For several years, many interventions have been established to reduce the prevalence of childhood obesity. However, these interventions have not adequately utilized existing models of behavior change, and as a result, have been unsuccessful in increasing levels of

Childhood obesity is a growing public health concern in the United States. For several years, many interventions have been established to reduce the prevalence of childhood obesity. However, these interventions have not adequately utilized existing models of behavior change, and as a result, have been unsuccessful in increasing levels of physical activity and healthy dietary intake. One such model of change, the Transtheoretical Model, views behavior change as occurring through a series of stages with progression through the stages being facilitated by cognitive and behavioral processes. Within these processes the constructs of consciousness-raising, helping relationships, and self-efficacy have been shown to be most influential in changing behaviors. Thus, the objective of this paper is to evaluate the effectiveness of such constructs and establish a multi-faceted approach to combat this epidemic.
ContributorsWang, Janice (Author) / Broman, Tannah (Thesis director) / Hoffner, Kristin (Committee member) / Baldwin, Marjorie (Committee member) / Barrett, The Honors College (Contributor) / College of Health Solutions (Contributor)
Created2012-12
137840-Thumbnail Image.png
Description
Children's wellbeing has been of utmost concern to society, and recently this topic has taken a particular focus in both health and achievement. As the focus shifts towards promoting a healthier and more academically successful youth, the relationship between the two warrants investigation. Specifically, the relationship between physical fitness and

Children's wellbeing has been of utmost concern to society, and recently this topic has taken a particular focus in both health and achievement. As the focus shifts towards promoting a healthier and more academically successful youth, the relationship between the two warrants investigation. Specifically, the relationship between physical fitness and academic performance (i.e. grades) in 4th grade students was assessed. A cross-sectional design was used to assess physical fitness of children (M=9.39 years) by means of the FITNESSGRAM assessment tool. Third-quarter grades were used to measure academic performance. Relationships between the variables were determined through bivariate plots, Pearson product moment correlation analysis, independent t-tests, and a three-step regression analysis. The results show a significant relationship between students' aerobic fitness and academic performance. Furthermore, the findings of this study suggest incremental validity between aerobic fitness and academic performance, thus implying predictive value associated with increased physical fitness and academic achievement.
ContributorsMoore, Shannon (Author) / Kulinna, Pamela (Thesis director) / Hoffner, Kristin (Committee member) / Stylianou, Michalis (Committee member) / Barrett, The Honors College (Contributor) / College of Health Solutions (Contributor)
Created2012-12
137413-Thumbnail Image.png
Description
In this research we consider stochastic models of Glioblastoma Multiforme brain tumors. We first look at a model by K. Swanson et al., which describes the dynamics as random diffusion plus deterministic logistic growth. We introduce a stochastic component in the logistic growth in the form of a random growth

In this research we consider stochastic models of Glioblastoma Multiforme brain tumors. We first look at a model by K. Swanson et al., which describes the dynamics as random diffusion plus deterministic logistic growth. We introduce a stochastic component in the logistic growth in the form of a random growth rate defined by a Poisson process. We show that this stochastic logistic growth model leads to a more accurate evaluation of the tumor growth compared its deterministic counterpart. We also discuss future plans to incorporate individual patient geometry, extend the model to three dimensions and to incorporate effects of different treatments into our model, in collaboration with a local hospital.
ContributorsManning, Michael Clare (Author) / Kostelich, Eric (Thesis director) / Kuang, Yang (Committee member) / Gardner, Carl (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / School of Letters and Sciences (Contributor) / School of Human Evolution and Social Change (Contributor)
Created2013-12
147584-Thumbnail Image.png
Description

It is well known that the lack of care coordination in the healthcare system causes numerous problems including cost inefficiency and inconsistent care, specifically for complex pediatric and adult patients. Many pediatric patients have complex medical and social service needs which can be expensive for both the patient’s parents and

It is well known that the lack of care coordination in the healthcare system causes numerous problems including cost inefficiency and inconsistent care, specifically for complex pediatric and adult patients. Many pediatric patients have complex medical and social service needs which can be expensive for both the patient’s parents and the general healthcare system. Therefore, it is difficult for the healthcare system to deliver the highest quality care possible, due to the number of appointments that have to be scheduled (with some being out of state), the large volume of physical health records, and overall lack of time parents have to coordinate this care while also caring for themselves and other family members. It is integral to find a more efficient way to coordinate care for these patients, in order to improve overall care, cost efficiency, and outcomes. <br/>A number of stakeholders in Arizona came together to work on this problem over several years. They were funded through a PCORI Eugene Washington Engagement grant to investigators at ASU. This project, Take Action for Arizona's Children through Care Coordination: A Bridge to Action was developed in order to further develop a research agenda and build the network (PCOR). Regional conferences were conducted in Flagstaff, Yuma, Phoenix, and Tucson, as well as a final capstone conference held in Phoenix. At these conferences, frustrations, suggestions, and opinions regarding Children with Special Health Care Needs (CSHCN) and navigating the healthcare system were shared and testimonials were transcribed.<br/>This study focused on the capstone conference. The study design was a strategic design workshop; results of the design analysis were analyzed qualitatively using descriptive content analysis. Themes described parent’s common experiences navigating the system, impacts resulting from such experiences, and desires for the care coordination system. Quotes were then grouped into major themes and subthemes for the capstone conference. After these themes were determined, the overarching goals of stakeholders could be assessed, and implementation projects could be described.

ContributorsBrennan, Bayley (Author) / Doebbeling, Bradley (Thesis director) / Lamb, Gerri (Committee member) / College of Health Solutions (Contributor, Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
147749-Thumbnail Image.png
Description

This thesis discusses why there is so much employee turnover in the Sports Programs department, which is a working department of the Sun Devil Fitness Complex on Arizona State’s Tempe Campus. The analysis discusses the problems that have been noticed from personal experience, and the problems that have been

This thesis discusses why there is so much employee turnover in the Sports Programs department, which is a working department of the Sun Devil Fitness Complex on Arizona State’s Tempe Campus. The analysis discusses the problems that have been noticed from personal experience, and the problems that have been explained by employees that left about why they decided to leave. The analysis is done based on the concepts of the four frames, based on research documented by Bolman and Deal in their book. There is an overview of all of the departments and specifically the Sports Programs department, and a deep dive into what that department does. There is a discussion of what problems may be present, and some solutions such as debriefings, trainings, and more objective evaluations that can be implemented into the department to try to fix the problems that have been noticed.

ContributorsRoegge, Kylie Anne (Author) / deLusé, Stephanie (Thesis director) / Cobb, Ethan (Committee member) / School of International Letters and Cultures (Contributor) / College of Health Solutions (Contributor) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05