VictorJuiz/thesis huggingface dataset:
Electronic Band Structure Tuning of Highly-Mismatched-Alloys for Energy Conversion Applications

Highly-mismatched alloys: ZnO1-xTex and GaN1-xSbx are discussed within the context of finding the suitable material for a cost-effective Si-based tandem solar cell (SBTSC). SBTSC is an attractive concept for breaking through the energy conversion efficiency theoretical limit of a single junction solar cell. Combining with a material of 1.8 eV band gap, SBTSC can theoretically achieve energy conversion efficiency > 45%./nZnO and GaN are wide band gap semiconductors. Alloying Te in ZnO and alloying Sb in GaN result in large band gap reduction to < 2 eV from 3.3 eV and 3.4 eV respectively. The band gap reduction is majorly achieved by the upward shift of valence band (VB). Incorporating Te in ZnO modifies the VB of ZnO through the valence-band anticrossing (VBAC) interaction between localized Te states and ZnO VB delocalized states, which forms a Te-derived VB at 1 eV above the host VB. Similar band structure modification is resulted from alloying Sb in GaN. ZnO1-xTex and GaN1-xSbx thin films are synthesized across the whole composition range by pulsed laser deposition (PLD) and low temperature molecular beam epitaxy (LT-MBE) respectively. The electronic band edges of these alloys are measured by synchrotron X-ray absorption, emission, and the X-ray photoelectron spectroscopies. Modeling the optical absorption coefficient with the band anticrossing (BAC) model revealed that the Te and Sb defect levels to be at 0.99 eV and 1.2 eV above the VB of ZnO and GaN respectively. Electrically, ZnO1-xTex is readily n-type conductive and GaN1-xSbx is strongly p-type conductive. A heterojunction device of p-type GaN0.93Sb0.07 with n-type ZnO0.77Te0.93 upper cell (band gap at 1.8 eV) on Si bottom cell is proposed as a promising SBTSC device.

Advisor: Mao, Samuel S
Greif, Ralph
The relationship between the D4 Dopamine Receptor gene (DRD4) and the emotion of awe

The subject of the current work is a highly polymorphic region on the gene coding for D4 type dopamine receptors (DRD4) consisting of a variable number of tandem repeats (VNTR) of a 48 base pair sequence. Convergent evidence from psychology, population genetics and animal behavior research support the important role the DRD4 VNTR polymorphism plays in promoting exploratory behavior./nAwe is an emotion felt in the presence of vast stimuli that are not accounted for by existing mental schema (Keltner & Haidt, 2003). In the current work I made the claim that awe signals the opportunity for exploration. Given the demonstrated relationship between the DRD4 VNTR polymorphism and exploratory behavior, the main aim of the current work is to test the relationship between this polymorphism and emotional reactivity to awe-eliciting situations. Specifically, I hypothesized that people with DRD4 VNTR variants that have been associated with exploratory behavior (carriers) would experience more awe than people who do not have those variants (non-carriers) across a range of situations./nStudy 1 used a college sample to test this hypothesis, both in a controlled laboratory environment and in people’s daily lives using diary methodology. Specifically, in a laboratory setting, carriers reported more awe than non-carriers in response to a film clip that had been validated as a reliable elicitor or awe, but no differences were found between groups in response to film clips that elicited compassion and amusement. Furthermore, analyses of daily diary data showed a trend such that carriers reported more awe across a 14-day diary period than non-carriers. Study 2, an ecologically valid test of my hypothesis, found that in a sample of adolescents from underserved communities who went white-water rafting, carriers reported more awe than non-carriers. Importantly, DRD4 VNTR did not have a consistent effect on any of the other emotions measured across these three contexts. I discussed the implications these findings have for our understanding of the emotion of awe and programs that aim to increase well-being through the experience of awe.

Advisor: Keltner, Dacher
Altruism and Efficiency Preferences of U.S Medical Students and Their Expected Specialty Choice

The quality of a nation's healthcare system depends heavily on physicians. Particularly in the U.S., a significant portion of a physician's job involves balancing among three often competing interests: their own financial self-interest, patients' economic or health interests, and the interests of the payers representing the larger healthcare system. Physician choices in the face of these tradeoffs depend on physicians’ underlying social preferences regarding factors including altruism and efficiency, on which previous literature has provided little direct insight./nWe measure the social preferences of a sample of 503 medical students from schools around the U.S. using an experimental approach. The approach allows us to decompose social preferences into two qualitatively different tradeoffs: the tradeoff between self-interest and other’s benefit (altruism), and the tradeoff between equality and efficiency. The experimental design consists of a set of computer-based revealed preference decision problems, which ask the experimental subjects to allocate real money between themselves and an anonymous person. We also collect rich individual-level information for the same sample from a survey we fielded. We examine heterogeneity in social preferences of medical students by expected specialty choice, with particular emphasis on specialty choice. Large variation in income and practice patterns across specialties in the U.S. means that in certain specialties, less altruistic behavior of physicians can yield significant financial gains, and less regard for efficiency can potentially lead to excessive waste./nWe find substantial heterogeneity in altruistic preferences among experimental subjects. Medical students with a lower degree of altruism are significantly more likely to choose high-income specialties: the half of the sample who are less altruistic in the experiment chooses specialties that earn on average around $40,000 more annually than their more altruistic peers. This altruism measure is more predictive of specialty than a wide range of other characteristics, including parental income, student loan amount and Medical College Admission Test (MCAT) score. We also find that this altruism measure predicts students' self-reported likelihood of practicing medicine in an underserved area.

Advisor: Dow, William H
Metagenomics adds unrecognized lineages to the tree of life and enables a genome-resolved view of microbiome dynamics

Microbes live in complex communities that have shaped the planet for billions of years. However, much is not known about their diversity and metabolic potential due to biases in methods that require cultivation or PCR amplification. Metagenomics circumvents these issues and can be used to obtain genome sequences for microbial community members. Approximately 800 metagenome-derived complete and draft-quality genomes were reconstructed for groundwater-associated bacteria from a radiation of previously unrecognized and little-known phyla with essentially no isolated representatives. Unlike most other bacteria, these organisms consistently have small genomes, lack highly conserved ribosomal proteins, frequently have rRNA gene introns, and have significant metabolic limitations indicative of an obligate symbiotic lifestyle. Combined phylogenetic and genomic analyses enabled recognition of this group as the Candidate Phyla Radiation (CPR), a major feature of domain Bacteria that was subsequently determined to comprise >50% of all bacterial diversity. Using a newly developed method called iRep, it was determined that CPR organisms typically replicate slowly, although they did replicate rapidly under some conditions. These in situ measurements were possible because iRep uses draft-quality genomes and metagenome sequencing to determine replication rates based on changes in genome copy number that occur during genome replication./nIn contrast to groundwater ecosystems, the human microbiome typically contains microorganisms from only a few phyla. Application of metagenomics enabled strain-level resolution of the human microbiome, measurement of iRep replication rates, and proteomic analyses of activity. Microbiome samples were collected from premature infants during the first months of life, and both metagenomics and metaproteomics were used to detect shifts in the gastrointestinal tract microbiome. Results showed that genetically similar bacteria behave differently depending on community context, leading to substantial changes in overall proteome composition. The metagenomic approach enabled identification of considerable genomic novelty. Analysis of the first genome sequence for a member of the genus Varibaculum uncovered a diverse repertoire of sugar utilization pathways and anaerobic respiration capacity. iRep analysis documented highly variable replication rates during initial colonization, and significantly higher rates following antibiotic administration. This work has added large and small branches to the tree of life with corresponding genomic and metabolic information, linked microbial responses and metabolism to changing environmental conditions, and provided previously unobtainable information on in situ replication rates.

Advisor: Banfield, Jillian F
Lives in the Balance: A Comparative Study of Public Social Investments in Early Childhood Across OECD Countries

Across the globe, the viability of welfare states depends on the success of policy adaptations to a post-industrial, internationalized economy and domestic demographic changes that encompass family formation, declines in fertility, and lifespan extensions of the elderly. One of the most important issues facing contemporary welfare states is the need to adjust social policy to the demise of the male breadwinner model in favor of the increased participation of women and mothers in the workforce. Whereas childrearing was traditionally the central occupation of stay-at-home mothers, their workforce participation has necessitated out-of-home care for children under the ages of five or six, before the start of primary school. Providing financial supports and investing in early childhood care and education are several policy instruments that can be used, not only to ease the burden of care faced by working mothers and their partners, but to promote the well-being and long-term economic productivity of their children as adults. In turn, the increased economic productivity of future generations can mitigate social risks and threats to the survival of the welfare state./nUsing a social investment approach based on human capital development in children, a set of indices is constructed to measure public investments in early childhood by ten member countries of the OECD from 2001 through 2011. The indices permit a theoretical exploration of patterns of expenditure and characteristics of policy design relative to their conformity to acknowledged types of welfare state regimes. The indices are also used to detect empirical changes in welfare state expenditures for early childhood investments pre- and post- the fiscal crisis of 2008. The study contributes to the literature of welfare state theory by situating investments in early childhood as a stage in the evolution of family policy; by creating a set of measures that characterizes public investments from a child-centered developmental perspective, one that is less prominent than work-family balance and gender equity viewpoints; and lastly, by combining expenditures and policy design components into a single measure.

Advisor: Gilbert, Neil
The Secret Lives of Plot

The Secret Lives of Plot is a study of the “plotter,” a seemingly peripheral but in fact necessary figure within the nineteenth-century novel and twentieth-century narrative cinema. A creature of ressentiment, melancholy, and political insufficiency, the plotter, although often cast as a minor or merely functional foil to a narrative’s more respectable cast of characters, nonetheless exerts a fascination at the levels of both narrative content and narrative form. The narratives I look at indeed rely on “low” moments of self-interested plotting—Frank Churchill’s flirting, Lady Audley’s bigamy, Miss Havisham’s revenge—in order to move their own plots forward, while also rooting for the failure of exactly the characters on whom they rely. What results is a strange and sometimes hypocritical entanglement between traditional narrative form and the frustrated desires of the arriviste, the social climber, the parasite, or the conspirator. If, as I argue, particular social and class distinctions persist as a set of formal problems embedded in the relationship between plot, literary character, and narration’s hierarchical structures of power, the plotter is one site at which social anxiety becomes narrative form. Often seen as the least complicated aspects of narrative form, plots and plotting emerge as points at which social anxiety is expressed in and informs the very logic of what we might call the novelistic. At its broadest level, my project addresses ways in which the plotter’s base and insatiable desire for the “mastery of form” that Pierre Bourdieu places at the crux of cultural refinement allows us to understand traditional narrative’s own self-consciousness about both its own aspirations toward aesthetic prestige and its fantasy of capturing a reality that remains always out of reach.

Advisor: Duncan, Ian
Miller, D. A.
Snake’s Tail: Modernism and the Paradox of Self-Reference

This dissertation explores how modernists envisioned thinking, judging, and acting in conditions of paradox. I hold modernism up against historical developments in logic, mathematics, and analytic philosophy to argue that T.S. Eliot, Robert Frost, Gertrude Stein, and I.A. Richards generated distinctive aesthetic, phenomenological, and affective responses to paradoxical situations. I anchor the work of these modernists in twentieth-century intellectual contexts with which they were all familiar, including the transition out of classical logic into a supposedly unparadoxical new symbolism; the waning of idealism and subsequent waxing of analytic philosophies; and the drive to “complete” mathematics. I demonstrate how modernists drew from these contexts the overarching problem of the liar paradox, whose paradoxical self-reference resisted all of logic’s attempts to resolve it. Articulating an aesthetics of paradox that is shaped by, yet often resistant to, these nascent new philosophies that were themselves defined by the liar paradox, modernists attend to the lived consequences, stylistic repercussions, and emotional tonalities of judging and acting in paradoxical situations./nI argue that they bear witness to logic’s struggles against paradox with profound consequences for narrative, poetics, form, and style. And I claim that they deepen approaches to logical thinking with a focus on what self-reference looks and feels like as an aesthetic experience: on paradoxes that link stylistic fragmentation with bodily harm (Eliot); self-referential structures that model human suffering (Frost); circular predicates that mimic processes of thought (Stein); and the metalinguistic consequences of self-reference in the context of close reading (Richards). Affective and stylistic dimensions of paradox mediate between the scales of concept, art, and intellectual history: Eliot’s poetic illusions and hallucinations emerge from grammatical self-reference and a graduate-level study of logic; Frost’s depictions of marital strife root in “unvicious circles” that mirror ones Frost studied at Harvard; Stein’s drive to capture consciousness in a totalizing self-referential style carries on a mathematical dream of completeness learned from A.N. Whitehead; and Richards’s metalinguistic project borrowed from logic to develop many of the formalist tools that literary scholars use to this day. Throughout I draw connections between these aesthetic presentations of paradox and our current literary practices, offering updated accounts of inference, evidence, figuration, and especially form—as logical concept, linguistic quodlibet, literary-critical object, and stylistic protocol.

Advisor: Altieri, Charles
Spontaneous Activity and Intrinsic Photosensitivity in the Developing Zebrafish Spinal Cord

The process of perception is one of the most complicated and compelling biological phenomena, capable of inspiring thousands of years of philosophers, physicians, and scientists. One of these researchers, Walter Freeman of Berkeley once stated, “The brain reaches out into the environment and sees something which is then interpreted according to its own past experiences. First you look, then you see.” While the neural computations involved in “seeing” may not be understood for many years to come, we have made much progress in understanding how the brain “looks” into its environment. And by studying animal behavior, we can hope to infer some understanding of the cells that transform these sensory inputs into motor outputs. Working with simple neural circuits—be they in model organisms or at early stages in development—the problem seems more tractable, yet new findings can shift our understanding of perception in unexpected ways./nIn this thesis, I present research on motor circuits of the embryonic zebrafish spinal cord. These spinal neurons directly drive the earliest muscle contractions in the fish and are a great model for understanding how activity begins in a nervous system. In the course of these studies, we discovered that the activity within this circuit is strongly inhibited by environmental light at an age before vision and before the spinal cord is connected to brain circuitry. Not all photoreceptors are for sight and there are many examples of deep brain photoreception in invertebrates and basal vertebrates, usually driving circadian and seasonal behaviors. Our finding in zebrafish is surprising due to the direct photodetection by motor neurons in the spinal cord, the developmentally early appearance of this photosensitivity, the possible role for primary cilia in sensing light, and the acute affect on behavior. Additionally, by manipulating spontaneous activity within this circuit, we see effects on the development of neural activity in spinal interneurons. These results change how we think about motor circuits and development. No longer are motor neurons simply passive relay cells, we now can see them as sensory inputs. No longer is development in the spinal cord governed solely by genetic programs, but activity dependent processes can be regulated by the outside world. The existence of this category of nonvisual photoreceptor across taxa indicates a new way for the brain to “reach out into the environment.” Discovering whether and how it alters our perception of the world will hopefully be a focus of future research.

Advisor: Isacoff, Ehud Y
Understanding Latency Hiding on GPUs

Modern commodity processors such as GPUs may execute up to about a thousand of physical threads per chip to better utilize their numerous execution units and hide execution latencies. Understanding this novel capability, however, is hindered by the overall complexity of the hardware and complexity of typical workloads. In this dissertation, we suggest a better way to understand modern multithreaded performance by considering a family of synthetic workloads, which use the same key hardware capabilities – memory access, arithmetic operations, and multithreading – but are otherwise as simple as possible./nOne of our surprising findings is that prior performance models for GPUs fail on these workloads: they mispredict observed throughputs by factors of up to 1.7. We analyze these prior approaches, identify a number of common pitfalls, and discuss the related subtleties in understanding concurrency and Little’s Law. Also, we help to further our understanding by considering a few basic questions, such as on how different latencies compare with each other in terms of latency hiding, and how the number of threads needed to hide latency depends on basic parameters of executed code such as arithmetic intensity. Finally, we outline a performance modeling framework that is free from the found limitations./nAs a tangential development, we present a number of novel experimental studies, such as on how mean memory latency depends on memory throughput, how latencies of individual memory accesses are distributed around the mean, and how occupancy varies during execution.

Advisor: Demmel, James W
Discourse, Disaster, and the Urban Hazardscape: The political ecology of climate and disasters after Hurricane Sandy

This dissertation examines how the phenomenon of climate change is changing the public conception of natural disasters, and vice versa. Using the aftermath of Hurricane Sandy in New York City as a case study, this project draws on a year of in-depth fieldwork triangulated with media coverage, public reports, and city-level quantitative data to illustrate how popular misconceptions about how disasters happen were at work in the public response to the catastrophe. In particular, my research develops a conceptual/nframework using discourse analysis, to identify two false doctrines or tropes which underlie many of these misconceptions. The first, the doctrine of natural disaster, asserts that environmental disasters are fundamentally physiological rather than social in origin. The second, the doctrine of disaster exceptionalism, asserts that so-called natural disasters are rare and unpredictable events. The results of this project indicate that while climate/nchange has the potential to disrupt these two false doctrines, this is not yet occurring in the public response to disaster. This dissertation also extends earlier work on the intersection of climate policy and environmental justice, known as the “climate gap”, and extends it to adaptation, proposing an “adaptation gap” is also at work. Finally, this dissertation proposes a new test for delineating different types of climate change adaptation, further developing work on what constitutes transformational adaptation.

Advisor: O'Neill, Kate