Matching Items (153)
Description
Diseases have been part of human life for generations and evolve within the population, sometimes dying out while other times becoming endemic or the cause of recurrent outbreaks. The long term influence of a disease stems from different dynamics within or between pathogen-host, that have been analyzed and studied by many researchers using mathematical models. Co-infection with different pathogens is common, yet little is known about how infection with one pathogen affects the host's immunological response to another. Moreover, no work has been found in the literature that considers the variability of the host immune health or that examines a disease at the population level and its corresponding interconnectedness with the host immune system. Knowing that the spread of the disease in the population starts at the individual level, this thesis explores how variability in immune system response within an endemic environment affects an individual's vulnerability, and how prone it is to co-infections. Immunology-based models of Malaria and Tuberculosis (TB) are constructed by extending and modifying existing mathematical models in the literature. The two are then combined to give a single nine-variable model of co-infection with Malaria and TB. Because these models are difficult to gain any insight analytically due to the large number of parameters, a phenomenological model of co-infection is proposed with subsystems corresponding to the individual immunology-based model of a single infection. Within this phenomenological model, the variability of the host immune health is also incorporated through three different pathogen response curves using nonlinear bounded Michaelis-Menten functions that describe the level or state of immune system (healthy, moderate and severely compromised). The immunology-based models of Malaria and TB give numerical results that agree with the biological observations. The Malaria--TB co-infection model gives reasonable results and these suggest that the order in which the two diseases are introduced have an impact on the behavior of both. The subsystems of the phenomenological models that correspond to a single infection (either of Malaria or TB) mimic much of the observed behavior of the immunology-based counterpart and can demonstrate different behavior depending on the chosen pathogen response curve. In addition, varying some of the parameters and initial conditions in the phenomenological model yields a range of topologically different mathematical behaviors, which suggests that this behavior may be able to be observed in the immunology-based models as well. The phenomenological models clearly replicate the qualitative behavior of primary and secondary infection as well as co-infection. The mathematical solutions of the models correspond to the fundamental states described by immunologists: virgin state, immune state and tolerance state. The phenomenological model of co-infection also demonstrates a range of parameter values and initial conditions in which the introduction of a second disease causes both diseases to grow without bound even though those same parameters and initial conditions did not yield unbounded growth in the corresponding subsystems. This results applies to all three states of the host immune system. In terms of the immunology-based system, this would suggest the following: there may be parameter values and initial conditions in which a person can clear Malaria or TB (separately) from their system but in which the presence of both can result in the person dying of one of the diseases. Finally, this thesis studies links between epidemiology (population level) and immunology in an effort to assess the impact of pathogen's spread within the population on the immune response of individuals. Models of Malaria and TB are proposed that incorporate the immune system of the host into a mathematical model of an epidemic at the population level.
ContributorsSoho, Edmé L (Author) / Wirkus, Stephen (Thesis advisor) / Castillo-Chavez, Carlos (Thesis advisor) / Chowell-Puente, Gerardo (Committee member) / Arizona State University (Publisher)
Created2011
Description
The repression of reproductive competition and the enforcement of altruism are key components to the success of animal societies. Eusocial insects are defined by having a reproductive division of labor, in which reproduction is relegated to one or few individuals while the rest of the group members maintain the colony and help raise offspring. However, workers have retained the ability to reproduce in most insect societies. In the social Hymenoptera, due to haplodiploidy, workers can lay unfertilized male destined eggs without mating. Potential conflict between workers and queens can arise over male production, and policing behaviors performed by nestmate workers and queens are a means of repressing worker reproduction. This work describes the means and results of the regulation of worker reproduction in the ant species Aphaenogaster cockerelli. Through manipulative laboratory studies on mature colonies, the lack of egg policing and the presence of physical policing by both workers and queens of this species are described. Through chemical analysis and artificial chemical treatments, the role of cuticular hydrocarbons as indicators of fertility status and the informational basis of policing in this species is demonstrated. An additional queen-specific chemical signal in the Dufour's gland is discovered to be used to direct nestmate aggression towards reproductive competitors. Finally, the level of actual worker-derived males in field colonies is measured. Together, these studies demonstrate the effectiveness of policing behaviors on the suppression of worker reproduction in a social insect species, and provide an example of how punishment and the threat of punishment is a powerful force in maintaining cooperative societies.
ContributorsSmith, Adrian A. (Author) / Liebig, Juergen (Thesis advisor) / Hoelldobler, Bert (Thesis advisor) / Gadau, Juergen (Committee member) / Johnson, Robert A. (Committee member) / Pratt, Stephen (Committee member) / Arizona State University (Publisher)
Created2011
Description
This dissertation explores the lives of women who are on the Severely Mentally Ill (SMI) caseload at Maricopa County Adult Probation in Arizona (The Phoenix metro region). The project focuses on three primary issues: (1) what are the pathways to the criminal justice and mental health systems for women on the SMI caseload (2) how does discretion and expansive formal social control (both benevolent and coercive) impact the lives of these women on the SMI caseload and (3) what are the gendered aspects to successful completion of SMI probation. To answer these questions a mixed-methods research design was employed. First, in-depth semi-structured interviews were completed with 65 women on the SMI caseload. Second, these interviews were supplemented with a case file review of each participant, and field observations (encompassing roughly 100 hours) were conducted at the Maricopa County Mental Health Court. Third, analysis also included 5.5 years of quantitative intake data from the SMI caseload, exploring demographic information and risk and assessment needs scores. The biographies of the women on the SMI caseload revealed similar histories of victimization, substance abuse, and relationship difficulty that previous pathways research has noted. Additionally, mental health problems directly impacted the path to the criminal justice system for some women on the SMI caseload. Results also showed many aspects of expanded social control for women on the SMI caseload. This expanded control appeared to be gendered at times and often created double binds for women. Finally, quantitative analysis showed that some predictive factors of SMI probation completion were gendered. Policy implications and summaries of findings are discussed.
ContributorsMulvey, Philip (Author) / Decker, Scott H. (Thesis advisor) / Spohn, Cassia (Committee member) / Holtfreter, Kristy (Committee member) / Arizona State University (Publisher)
Created2013
Description
ABSTRACT 1. Aposematic signals advertise prey distastefulness or metabolic unprofitability to potential predators and have evolved independently in many prey groups over the course of evolutionary history as a means of protection from predation. Most aposematic signals investigated to date exhibit highly chromatic patterning; however, relatives in these toxic groups with patterns of very low chroma have been largely overlooked. 2. We propose that bright displays with low chroma arose in toxic prey species because they were more effective at deterring predation than were their chromatic counterparts, especially when viewed in relatively low light environments such as forest understories. 3. We analyzed the reflectance and radiance of color patches on the wings of 90 tropical butterfly species that belong to groups with documented toxicity that vary in their habitat preferences to test this prediction: Warning signal chroma and perceived chromaticity are expected to be higher and brightness lower in species that fly in open environments when compared to those that fly in forested environments. 4. Analyses of the reflectance and radiance of warning color patches and predator visual modeling support this prediction. Moreover, phylogenetic tests, which correct for statistical non-independence due to phylogenetic relatedness of test species, also support the hypothesis of an evolutionary correlation between perceived chromaticity of aposematic signals and the flight habits of the butterflies that exhibit these signals.
ContributorsDouglas, Jonathan Marion (Author) / Rutowski, Ronald L (Thesis advisor) / Gadau, Juergen (Committee member) / McGraw, Kevin J. (Committee member) / Arizona State University (Publisher)
Created2013
Description
The study of non-U.S. citizens in criminal justice system outcomes has often been neglected in the sentencing literature. When citizenship is considered, there are generally no distinctions made within this group. The research fails to consider differences according to legal status, race/ethnicity, nationality and other distinctive markers that might play a role in sentencing outcomes. Using federal sentencing data collected by the United States Sentencing Commission for fiscal year 2006 through fiscal year 2008, this study examines the effect of offender citizenship status, legal status, and national origin on the likelihood of imprisonment and length of imprisonment for offenders convicted of drug offenses. The current study considers differences among foreign-born and Latino immigrant subgroups (e.g., Colombian, Cuban, Dominican, and Mexican nationals). The key findings in this dissertation include: (1) non-U.S. citizens have greater odds of imprisonment than U.S. citizens. However, non-U.S. citizen offenders receive significantly shorter prison terms relative to U.S. citizen offenders; (2) undocumented immigrants are more likely to be incarcerated compared to similarly situated authorized immigrants and U.S. citizens. However, legal status does not have an effect on sentence length; and (3) with respect to national origin, Mexican nationals are significantly more likely than Colombians to be incarcerated and are given significantly longer prison sentences than Dominican nationals. The implications of these findings and future research are addressed in the concluding chapter.
ContributorsValadez, Mercedes (Author) / Spohn, Cassia (Thesis advisor) / Wang, Xia (Committee member) / Wright, Kevin (Committee member) / Arizona State University (Publisher)
Created2013
Description
Solution methods for certain linear and nonlinear evolution equations are presented in this dissertation. Emphasis is placed mainly on the analytical treatment of nonautonomous differential equations, which are challenging to solve despite the existent numerical and symbolic computational software programs available. Ideas from the transformation theory are adopted allowing one to solve the problems under consideration from a non-traditional perspective. First, the Cauchy initial value problem is considered for a class of nonautonomous and inhomogeneous linear diffusion-type equation on the entire real line. Explicit transformations are used to reduce the equations under study to their corresponding standard forms emphasizing on natural relations with certain Riccati(and/or Ermakov)-type systems. These relations give solvability results for the Cauchy problem of the parabolic equation considered. The superposition principle allows to solve formally this problem from an unconventional point of view. An eigenfunction expansion approach is also considered for this general evolution equation. Examples considered to corroborate the efficacy of the proposed solution methods include the Fokker-Planck equation, the Black-Scholes model and the one-factor Gaussian Hull-White model. The results obtained in the first part are used to solve the Cauchy initial value problem for certain inhomogeneous Burgers-type equation. The connection between linear (the Diffusion-type) and nonlinear (Burgers-type) parabolic equations is stress in order to establish a strong commutative relation. Traveling wave solutions of a nonautonomous Burgers equation are also investigated. Finally, it is constructed explicitly the minimum-uncertainty squeezed states for quantum harmonic oscillators. They are derived by the action of corresponding maximal kinematical invariance group on the standard ground state solution. It is shown that the product of the variances attains the required minimum value only at the instances that one variance is a minimum and the other is a maximum, when the squeezing of one of the variances occurs. Such explicit construction is possible due to the relation between the diffusion-type equation studied in the first part and the time-dependent Schrodinger equation. A modication of the radiation field operators for squeezed photons in a perfect cavity is also suggested with the help of a nonstandard solution of Heisenberg's equation of motion.
ContributorsVega-Guzmán, José Manuel, 1982- (Author) / Sulov, Sergei K (Thesis advisor) / Castillo-Chavez, Carlos (Thesis advisor) / Platte, Rodrigo (Committee member) / Chowell-Puente, Gerardo (Committee member) / Arizona State University (Publisher)
Created2013
Description
Criminologists have directed significant theoretical and empirical attention toward the institution of marriage over the past two decades. Importantly, the momentum guiding this line of research has increased despite the fact that people are getting married far less often and much later in the life course than in any point in American history. The aim of this dissertation is to address this disconnect by focusing attention to nonmarital romantic relationships and their instability during emerging adulthood. To do so, it uses data from the Pathways to Desistance Study, a longitudinal study of 1,354 at-risk males and females who were adjudicated from the juvenile and adult systems in Phoenix and Philadelphia between 2000 and 2003. The project focuses attention to the following issues: (1) the effect of romantic dissolution on aggressive and income-based offenses; (2) the extent to which strain
egative emotionality and peer influence/exposure account for the effect of romantic dissolution on crime; and (3) the extent to which certain relationship and individual circumstances moderate the effect of romantic dissolution. The models reveal a few key findings. First, romantic dissolution is strongly related to an increase in both aggressive and income-based crime, but is more strongly related to income-based crime. Second, the effect of romantic dissolution is reduced when measures of strain
egative emotionality and peer influence/exposure measures are added to models, but the peer influence/exposure measures account for the strongest reduction. Finally, romantic dissolution does not serve as a positive life event among these at-risk youth, but its effect is exacerbated under a number of contexts (e.g. when an individual is unemployed). This study closes with a summary of these findings as well as its key limitations, and offers insight into potential policy implications and avenues of future research.
egative emotionality and peer influence/exposure account for the effect of romantic dissolution on crime; and (3) the extent to which certain relationship and individual circumstances moderate the effect of romantic dissolution. The models reveal a few key findings. First, romantic dissolution is strongly related to an increase in both aggressive and income-based crime, but is more strongly related to income-based crime. Second, the effect of romantic dissolution is reduced when measures of strain
egative emotionality and peer influence/exposure measures are added to models, but the peer influence/exposure measures account for the strongest reduction. Finally, romantic dissolution does not serve as a positive life event among these at-risk youth, but its effect is exacerbated under a number of contexts (e.g. when an individual is unemployed). This study closes with a summary of these findings as well as its key limitations, and offers insight into potential policy implications and avenues of future research.
ContributorsLarson, Matthew Joseph (Author) / Sweeten, Gary (Thesis advisor) / Piquero, Alex (Committee member) / Spohn, Cassia (Committee member) / Wallace, Danielle (Committee member) / Arizona State University (Publisher)
Created2013
Description
Of all the signals and cues that orchestrate the activities of a social insect colony, the reproductives' fertility pheromones are perhaps the most fundamental. These pheromones regulate reproductive division of labor, a defining characteristic of eusociality. Despite their critical role, reproductive fertility pheromones are not evenly expressed across the development of a social insect colony and may even be absent in the earliest colony stages. In the ant Camponotus floridanus, queens of incipient colonies do not produce the cuticular hydrocarbons that serve as fertility and egg-marking signals in this species. My dissertation investigates the consequences of the dramatic change in the quantity of these pheromones that occurs as the colony grows. C. floridanus workers from large, established colonies use egg surface hydrocarbons to discriminate among eggs. Eggs with surface hydrocarbons typical of eggs laid by established queens are nurtured, whereas eggs lacking these signals (i.e., eggs laid by workers and incipient queens) are destroyed. I characterized how workers from incipient colonies responded to eggs lacking queen fertility hydrocarbons. I found that established-queen-laid eggs, incipient-queen-laid eggs, and worker-laid eggs were not destroyed by workers at this colony stage. Destruction of worker-laid eggs is a form of policing, and theoretical models predict that policing should be strongest in incipient colonies. Since there was no evidence of policing by egg-eating in incipient C. floridanus colonies, I searched for evidence of another policing mechanism at this colony stage. Finding none, I discuss reasons why policing behavior may not be expressed in incipient colonies. I then considered the mechanism that accounts for the change in workers' response to eggs. By manipulating ants' egg experience and testing their egg-policing decisions, I found that ants use a combination of learned and innate criteria to discriminate between targets of care and destruction. Finally, I investigated how the increasing strength of queen-fertility hydrocarbons affects nestmate recognition, which also relies on cuticular hydrocarbons. I found that queens with strong fertility hydrocarbons can be transferred between established colonies without aggression, but they cannot be introduced into incipient colonies. Queens from incipient colonies cannot be transferred into incipient or established colonies.
ContributorsMoore, Dani (Author) / Liebig, Juergen (Thesis advisor) / Gadau, Juergen (Committee member) / Pratt, Stephen (Committee member) / Smith, Brian (Committee member) / Rutowski, Ronald (Committee member) / Arizona State University (Publisher)
Created2012
Description
The development of the vertebrate musculoskeletal system is a highly dynamic process, requiring tight control of the specification and patterning of myogenic, chondrogenic and tenogenic cell types. Development of the diverse musculoskeletal lineages from a common embryonic origin in the paraxial mesoderm indicates the presence of a regulatory network of transcription factors that direct lineage decisions. The basic helix-loop-helix transcription factor, PARAXIS, is expressed in the paraxial mesoderm during vertebrate somitogenesis, where it has been shown to play a critical role in the mesenchymal-to-epithelial transition associated with somitogenesis, and the development of the hypaxial skeletal musculature and axial skeleton. In an effort to elucidate the underlying genetic mechanism by which PARAXIS regulates the musculoskeletal system, I performed a microarray-based, genome-wide analysis comparing transcription levels in the somites of Paraxis-/- and Paraxis+/+ embryos. This study revealed targets of PARAXIS involved in multiple aspects of mesenchymal-to-epithelial transition, including Fap and Dmrt2, which modulate cell-extracellular matrix adhesion. Additionally, in the epaxial dermomyotome, PARAXIS activates the expression of the integrin subunits a4 and a6, which bind fibronectin and laminin, respectively, and help organize the patterning of trunk skeletal muscle. Finally, PARAXIS activates the expression of genes required for the epithelial-to-mesenchymal transition and migration of hypaxial myoblasts into the limb, including Lbx1 and Met. Together, these data point to a role for PARAXIS in the morphogenetic control of musculoskeletal patterning.
ContributorsRowton, Megan (Author) / Rawls, Alan (Thesis advisor) / Wilson-Rawls, Jeanne (Committee member) / Kusumi, Kenro (Committee member) / Gadau, Juergen (Committee member) / Arizona State University (Publisher)
Created2013
Description
The purpose of this project is to better understand the factors associated with, and effects of, prison visitation for children during maternal and paternal incarceration. As gatekeepers, caregivers play a pivotal role in the facilitation of parent-child prison visitation. Yet, some caregivers may be more likely to take children to visit than others. Additionally, among those children who do visit, visitation may be positive in some ways and negative in others. To advance prior work, this study (1) assesses the relationship between caregiver type and parent-child prison visitation and (2) investigates the emotional and behavioral responses of children who visit. The current research uses mixed-methods and is carried out in two phases. For Phase 1, quantitative data on 984 children collected from structured interviews with incarcerated parents (N=279 mothers; N=143 fathers) in the Arizona Department of Corrections are used to examine the relationship between caregiver type and the likelihood of parent-child prison visitation. Descriptive statistics and logistic regression analyses are conducted separately for maternal and paternal incarceration. Phase 2 draws on caregivers' accounts of 40 children who visit their parent in prison to assess children's emotional and behavioral reactions to visitation. Data are coded to identify positive and negative responses, "visitation paradox" indicators, prior life circumstances and child age. Thematic content analyses are conducted to capture major themes. Analyses from Phase 1 confirm a significant relationship between caregiver type and mother-child and father-child visitation. Other factors that affected the likelihood of parental visitation included child situational factors, parent stressors, institutional barriers and child demographics, although these effects differed depending upon which parent was in prison. Results from Phase 2 revealed overwhelmingly negative responses among children to parental prison visitation. Key themes that accounted for child reactions included institutional context and parental attachment. This research adds to the collateral consequences of incarceration literature by providing greater insight into the imprisonment experience for vulnerable families. Further, these results have direct implications for correctional policy and practice pertaining to the manner and regulation of prison visits and also inform reentry efforts through a family-centric approach.
ContributorsTasca, Melinda (Author) / Rodriguez, Nancy (Thesis advisor) / Spohn, Cassia (Committee member) / Zatz, Marjorie S (Committee member) / Arizona State University (Publisher)
Created2014