Filter Results
6975 results
Creating interventions to avoid adverse events is an ongoing topic in numerous settings and thus it is often important to answer questions such as which treatments can be applied to avoid outcomes such as death or stunted growth. One may hope to answer these queries through the use of variable importance measures and through modeling the growth and development of individuals. Variable importance is an up and coming aspect of statistics that ranks variables in terms of some measure of importance which is often applied without the notion of either the exact meaning or how it can be compared with other regression or classification methods. Thus, characterizing standard variable importance measures could go a long way in the applicability and practicality of these ideas. In addition, confidence intervals and a lower threshold of importance was created and explored in order to advance the understanding and interpretability of such measures and methods. Simulations were conducted to show the behavior of such metrics with theoretical results stemming from a simple setting. In a specific population of Bangladeshi children from the PROVIDE study, growth models were explored where previous models have not correctly described these children's heights over the first two years of time, especially considering the plethora of covariates (900+). Developmental outcomes from 2 to 5 years of age were additionally modeled and explored. Throughout this research, the variable importance is described and explored in diverse manners while the children's heights and development is explained through various inclusive models.
Data Types:
  • Document
This dissertation explores students’ access to high-quality information and advisors to help them advance through the K-12 education system and into the postsecondary system. Financial aid policies are an example of one type of high-resource, high-intensity intervention to address income gaps in college-going. However, there are several other potential policy interventions that address the non-pecuniary resources students need to navigate the education system, and there are several leverage points earlier in students’ education trajectory that merit intervention well before students make the decision about whether and where to apply to college.
Data Types:
  • Document
This dissertation introduces various cultural reponses to the 2008 social and financial crisis in Spain. In particular, the project identifies key outcomes of the actual crash and demonstrates how cultural works have depicted the catastrophe. My work underscores other functions of these artistic manifestations ranging from providing catharsis to encouraging protest and activism. The dissertation explores multiple cultural phenomena including novel, theatre, film, television, comic, and street performance. It offers the first critical analysis of many of these texts. In the Introduction, I highlight the historical background leading up to the 2008 recession and discuss the consequences of the disaster. I point to culture as a means to move beyond numbers and figures in order to illuminate the human suffering and response to the crash. In this chapter, I offer an overview of previous scholarship on the crisis and cultural production and point to the need for an ongoing conversation. I underscore that my dissertation fills a void in the study of these phenomena by providing an analysis of multiple mediums. Chapter One discusses the first thematic response to the crisis: suffering and marginality. It demonstrates the human dimension of the disaster through analyses of the play Iphigenia en Vallecas, Isaac Rosa’s comic, Aquí vivió, and Icíar Bollaín’s film, El olivo. Chapter Two centers on the mass Spanish emigration that occurred after the advent of the crisis. The chapter provides an overview of recent Spanish migration patterns and how these are represented through culture. Venirse arriba (2014), by Borja Cobeaga and Diego San José, Blitz (2015), by David Trueba, the film Perdiendo el norte (2015), directed by Nacho Velilla, as well as the television series, Buscando el norte (2016), created by Nacho Velilla, Oriol Capel, David Olivas, and Antonio Sánchez serve as case studies to represent this phenomenon. Chapter Three examines how culture can serve as a mode of protest through an analysis of María Folguera’s novel, Los primeros días de Pompeya (2016), Alberto San Juan’s play, Masacre: Una historia del capitalismo español (2017), and the Flo6x8 flamenco flash-mob group.
Data Types:
  • Document
In the past two decades, contemporary nature poetry has increasingly abandoned traditional representations of nature, instead privileging the complex and often messy entanglements that characterize our climate change era. Jorie Graham’s 2008 poetry collection, Sea Change, stands out among this group for its depiction of the material and affective relations between human and nonhuman life in a time of profound ecological crisis. This thesis argues that Sea Change draws on new materialist concepts to articulate a posthuman or more-than-human subjectivity and ethics for the Anthropocene, a relational mode of being oriented towards principles of non-mastery. Departing from more radical formulations of ecological poetry that would attempt to eliminate the human subject and voice altogether, Graham’s work balances her concern for the “in- / dispensable plankton” with the lyric intimacy and minutiae of human life. In doing so, Sea Change enlivens the theoretical debates surrounding subjectivity and ethics in the Anthropocene, helping us to imagine how we, Graham’s readers, might begin to exhibit these selves in our everyday life.
Data Types:
  • Document
The collective action of microbes that colonize humans, known as their microbiota, has emerged as a major force influencing health and disease. Appreciation for this influence has grown exponentially in recent years thanks to advances in high-throughput sequencing technologies that were coupled with key concepts in microbial ecology and evolution linking sequence to phylogeny. Although studies utilizing these technologies, and the analytic methods also required to enable them, have greatly advanced our understanding of the potential impact of the microbiota on human health, we still lack systematic methods for interrogating the mechanisms responsible for the numerous associations we have identified. In this dissertation, I present my work which accelerates our ability to develop actionable hypotheses from associations observed in studies of the microbiota. This work is divided into data-driven approaches for inferring metabolic mechanisms governing interspecies interactions (Chapter 2), and model-driven approaches for improving our understanding of metabolism for gut microbes (Chapters 3 and 4). In Chapter 2, I developed a method that establishes expected metabolic behavior within microbial communities based on the assumption of constant metabolite yield between mono- and co-culture conditions. Using this method, I identified global improvements in the efficiency of biomass production that occur in co-cultures in which a species experienced a growth benefit, and show that the method can be used to interrogate complex interspecies interactions such as cross feeding. In Chapters 3 and 4, I developed software and method for building and analyzing ensembles of genome-scale metabolic network reconstructions. I used these tools to address a key challenge in systems biology: how should curation of large mechanistic models be prioritized? I developed an ensemble generation, simulation, and analysis framework that identifies key curation targets that maximally reduce simulation uncertainty, thereby establishing the relative value of curating each portion of a metabolic network. In sum, the work in this dissertation represents advances in our ability to interrogate interactions between gut microbes as well as our ability to efficiently construct predictive models of metabolism for individual species.
Data Types:
  • Document
The first chapter of my dissertation investigates how student loans affect early-career decisions for low-income students. The University of Virginia’s (UVa) financial aid policy included an income threshold to determine whether students received approximately $5,500/year as a grant or a loan. I use the income threshold to employ a regression discontinuity (RD) approach. Moreover, a policy change replaced approximately $3,000/year of grant aid with loans for low-income students. I use the policy change to employ a difference-indifferences (DD) approach. I find that student loans did not impact enrollment at UVa or subsequent academic performance, such as GPA and degree completion. However, higher student loan levels increased the share of students who majored in business or economics by 6 percentage points and increased the share of students who accepted a job in a high-paying industry by 9 percentage points. There is suggestive evidence that student loans decreased the likelihood of students immediately attending graduate school after college. My findings show that debt leads students to alter their career path before reaching the labor market. The second chapter examines whether colleges respond to a financial incentive that could incentivize colleges to enroll more low-income students. I use variation in funding created by an accountability system in one state, which awards public colleges substantially higher funding for the outcomes of students who are below an income threshold. For example, public four-year colleges receive approximately $3,600 in additional state funding when such a student graduates. Using state-wide administrative data on high school graduates, I compare the enrollment of students around the income threshold. Overall, the regression discontinuity estimates show no difference in college attendance or choice of four-year versus two-year college. However, analysis by college selectivity shows that the public flagship responded to equity measure by enrolling more Pell-eligible students. There is suggestive evidence that the response by the flagship diverted ineligible students to less selective public four-year colleges. Using ACT scores to measure baseline academic ability, I find that these effects are largest among students who are likely on the margin of being accepted at the flagship. The third chapter examines the effects of conditional cash transfers on college enrollment. Together with Professor Ben Castleman, I designed and implemented a large-scale field experiment that encouraged a national sample of low-income, high-achieving students to apply to high-quality schools in their state. Students were randomized to receive: 1) a customized list of high-quality colleges in their state; or 2) the list of schools and an offer of $100 for applying to schools from their list. We find that the incentive offer increased the likelihood that students enrolled at a high-quality institution by 2.6 percentage points (4.5 percent) and reduced the share of students attending a lower-quality college. Impacts of the incentive were more than double in magnitude for low-income students. These results suggest that leveraging conditional cash transfers at high leverage decisions points—such as when students are choosing which colleges to apply to—could be an efficient use of resources to reduce socioeconomic disparities in the quality of higher education institution students attend.
Data Types:
  • Document
Same-sex parents in the United States live in a society that stigmatizes their intimate relationships. As a result, they may experience chronic stressors (e.g., rejection, stigma, and discrimination) as a product of their socially marginalized positions. It has been shown that such stressors are negatively associated with same-sex couples’ appraisal of their relationship quality and psychological well-being. Critical questions remain, however, regarding minority stress and its association with parenting by same-sex couples. At present, no studies have examined how experiences with discrimination and stigma may affect parents’ reports of their coparenting or parenting behaviors among sexual minority parents in the U.S. The current study used the minority stress and family stress models to examine links between stressors that are embedded in the social position of sexual minority people (i.e., minority stress) and parenting experiences among parents in same-sex relationships. The first aim of the study was to investigate whether minority stressors were associated with parents’ reports of their coparenting and parenting practices. The second aim was to determine the extent to which associations between minority stress and parents’ reports of their coparenting and parenting practices were mediated through parents’ depressive symptoms and relationship quality. Lastly, the third and final aim of the study was to test whether social support moderated associations between stress and parenting. The final sample consisted of 162 cisgender women and 24 cisgender men in same-sex relationships. Data from eligible parents were gathered using an online survey. Due to sample limitations, only data from sexual minority mothers were analyzed in the following analyses. As expected, internalized negative beliefs about one’s sexual orientation were significantly associated with less positive coparenting alliance. However, no evidence was found for other sources of minority stress—pressure to conceal one’s same-sex relationship and expectations of public rejection were not associated with either coparenting alliance or parenting behaviors. The association between minority stress and parenting outcomes was not found to be mediated by relationship quality or depressive symptoms. Relationship quality significantly moderated the association between depressive symptoms and coparenting alliance. Specifically, the association between depressive symptoms and coparenting was not significant for mothers with stronger relationship quality, but was significant for mothers who reported worse relationship quality. Taken together, these results contribute to our growing knowledge of sexual minority parents. First, they suggest that minority stress may have a significant association with coparenting alliance that is differentiated by the type of stress and that is separate from other contributing factors such as mental health and interparental relationship quality—after accounting for depressive symptoms and relationship quality, internalized homonegativity continued to explain a significant amount of variance in coparenting alliance. Second, these results provide further evidence that parenting among LGBTQ mothers is affected by processes germane to a multitude of different families (i.e., relationship quality and depressive symptoms). It is also noteworthy that these associations were significant despite the majority of mothers reporting relatively high levels of socioeconomic status and social support. These findings may help clinicians to adapt evidence-based, cognitive-behavioral interventions to better serve the needs of same-sex parenting couples.
Data Types:
  • Document
Underbody blasts (UBB) have become the most prevalent threats to soldiers in theater. These events typically occur from a bomb, mine, or improvised explosive device (IED), and are characterized by very high accelerations and short durations. During UBBs, life threatening injuries can occur when the pelvis is loaded from blast energy that is transmitted through the floor and into the seat of the vehicle. To better protect soldiers, a better understanding of how the pelvis is injured during UBBs is needed. Finite element models are commonly used to study injuries and can be used to test countermeasures to injury; however, modern pelvis finite element models lack high-rate material properties and are not suitable for simulating UBBs. The goal of this research is to find high-rate material properties of gluteal tissue and investigate the load path through the pelvis during vertical loading. To achieve this, the load response of eleven gluteal tissue specimens at high rates were captured through indentation of gluteal tissue specimens. A material model was created using an inverse finite element technique in which the tissue indentation of each specimen was simulated using specimen specific finite element models. The material properties were optimized through subsequent simulations until the error between the force response of the finite element models and the experimental tests was minimized. Then, a component pelvis finite element model was created to simulate previous pelvis UBB experimental tests. Boundary and input conditions were recreated, and the new tissue model was used for the gluteal tissue. Tools were then created to analyze the load path through the pelvis while being loaded vertically. It was found that in the loading rates tested, the rate of the impact did not affect the amount of load carried by the tissue or the load path through the pelvis. However, it was found that tissue thickness, tissue stiffness, and sacroiliac joint material properties all had significant effects on the effective load path through the pelvis. The insight from this thesis will assist ongoing research in understanding how the pelvis is injured during UBBs so that effective countermeasures can be created to protect soldiers in the battlefield.
Data Types:
  • Document
In the world today there exists a large number of problems that are of great societal concern, but suffer from a problem called the tragedy of the commons where there isn‘t enough individual incentive for people to change their behavior to benefit the whole. One of the biggest examples of this is in energy consumption where research has shown that we can reduce 20-50% of the energy used in buildings if people would consistently modify their behavior. However, consistent behavior modification to meet societal goals that are often low priority on a personal level is often prohibitively difficult in the long term. Even systems design to assist in meeting these needs may be unused or disabled if they require too much effort, infringe on privacy, or are frustratingly inaccurate. We need a way to automatically meet societal needs while reducing or eliminating the burden on users. The vision of Ambient Intelligence Environments (AmI) has been dedicated to meeting this and other human supportive goals since first being introduced in the late 1990s. Ambient intelligence environments are computational systems embedded in the physical environment that sense, reason about, and act for the benefit of the people in that environment and their objectives. The key factor, and challenge, of an ambient intelligence environment is that it serves its objectives invisibly and transparently, with little to no requirements on the user’s behavior or cognitive load, but still incorporates the user in all its actions. It is not by accessing a computer terminal that people interact with the system, but by normal interactions with their environment and the objects within. This seems ideal for meeting societal concerns where users do not want to put any additional effort into the system. This dissertation aims to explore some of the practical uses and challenges of sensing and reasoning in ambient intelligence environments. First, I show how AmI environments are needed to personalize solutions to societal needs, such as shifting the energy peak created by daily energy use. This personalization can improve widespread adoption by allowing a system to benefit every user and not just the average one. Then, I explore two novel solutions to the two main human-centric challenges in ambient intelligence environments that may prevent the adoption of solutions for meeting societal needs: privacy vs. data collection and having the human in the loop vs. automation. Privacy is challenging in AmI because personal data is needed to create personalization, but many systems collect more private data than they need for operation. We present a novel solution to one of the worst examples of this, cameras, by using hardware limitations to preserve privacy. Keeping humans in the loop in AmI is challenging since we cannot ask for their preferences and instead need to learn through their natural interactions with the environment. In physical AmI, the interactions used to learn such preferences are often few and far between, resulting in a “small data” problem for learning. This problem is further exacerbated as preferences change over time and the system must quickly adapt. We present a novel solution that leverages the similarity between users in reinforcement learning to quickly learn in the face of these challenges. We anticipate that this work and these solutions to the two challenges of AmI will increase the accuracy, privacy, and ultimate adoption of AmI technologies to meet societal needs.
Data Types:
  • Document
This digital portfolio comprises documents and media that represent the culmination of three years of graduate study at the University of Virginia Department of Drama. The portfolio and supplemental materials showcase a direct application of the author’s learning in the classroom to onstage performances, teaching, and building agency through the creation of original work as she transitions into the professional world.
Data Types:
  • Document