VictorJuiz/thesis huggingface dataset:
Terrestrial-Atmospheric Exchange of Reduced Sulfur Compounds in Natural Ecosystems

The sulfur biogeochemical cycle includes biotic and abiotic processes important to global climate, atmospheric chemistry, food security, and the study of related cycles. The largest flux of sulfur on Earth is weathering from the continents into the sulfate-rich oceans; one way in which sulfur can be returned to land is through transport of reduced sulfur gases via the atmosphere. Here I developed a method for quantifying low-level environmental fluxes of several sulfur-containing gases, H2S, COS, CH3SCH3 (DMS), and HSCH3, between terrestrial ecosystems and the atmosphere./nCOS is the most prevalent reduced sulfur gas in the atmosphere, considered to be inert in the troposphere except for its uptake in plant leaves and to a smaller extent aerobic soils. This dissertation reports two surprising cases that go against conventional thinking about the sulfur cycle. We found that the common salt marsh plant Batis maritima can mediate net COS production to the atmosphere. We also found that an aerobic wheat field soil produces COS abiotically when incubated in the dark at > 25 °C and at lower temperatures under light conditions. We then sought to separately quantify plant and soil sulfur gas fluxes by undertaking a year-long field campaign in a grassland with a Mediterranean climate, where green plants were present only half of the year. We measured in situ soil fluxes of COS and DMS during the non- growing dry season, using water additions to simulate soil fluxes of the growing, wet season. COS and CO2 are consumed in a predictable ratio by enzymes involved in photosynthetic pathways; however, while CO2 is released by back diffusion and autorespiration, COS is usually not generated by plants. Using measurements during the growing season, we were then able to calculate gross primary production by using the special relationship between CO2 and COS./nThis dissertation has developed a greater understanding of the vagaries of the atmospheric-terrestrial sulfur cycle and explored using that cycle as a tool for studying the carbon cycle.

Advisor: Rhew, Robert C
Engineering Collective Behaviors

Much of the world consists of many small things, animate or inanimate, interacting with each other to produce something larger than, and different from themselves. Comprising murders of crows, armies of ants, schools of fish, dunes of sand, and various organs in your body, the collective behaviors of these systems embody a different approach to engineering than we currently employ. This thesis explores three examples where principles from collective behaviors are deployed as engineering tools. The first example presents how the collective phenomenon of `percolation' can be leveraged to rapidly produce a low-cost, best-in-class strain gauge (100% strain with a linear output and gauge factor of 1) using collectives of carbon nanotubes. The second example discusses how a modified inkjet printer can be used to simulate morphogenetic inputs and thereby manipulate the spatiotemporal patterns of gene expression in bacterial colonies. The final example explores control of collective motion (canonical `swarming') through the use of bioelectric cues to herd epithelial cells in a manner analogous to how a sheepdog herds sheep.

Advisor: Maharbiz, Michel M
Essays in Behavioral Finance

This dissertation contains three essays in behavioral finance. It explores investors' (non-standard) behaviors and their impacts on market efficiency and market valuations. I strive to empirically characterize how market participants behave, and to identify how these behaviors can improve our understanding of the financial market./nThe first chapter studies the impact of prior investment experience in an industry on the subsequent purchase of new stocks in the same industry. Using trading records data for households at a large discount broker from 1991 to 1996, I establish that the experience of positive excess returns in a given industry increases the probability of purchasing similar stocks in that industry relative to other industries. This result is robust to industry momentum, wealth effects, and investor heterogeneity. The effect decays when the experience is further in the past. Furthermore, I find that investor sophistication mitigates this experience effect. These results are consistent with mechanisms where investors put more weight on their own experience than on other available historical information when updating the beliefs about an industry's future return. The results are also consistent with investors learning about their stock-picking ability in an industry from their experienced outcomes./nIn the second chapter, I ask the question: do investors slow to incorporate return-relevant information if it reflects firms' operations abroad? Using the corresponding industry return in the foreign countries, I show that foreign operations information is slowly incorporated into stock prices. A trading strategy exploiting the foreign operations information of multinational firms generates a monthly abnormal return of approximately $0.80$ percentage points, controlling for risk-based factors. The return predictability is not driven by U.S. industry momentum, global industry momentum or foreign country-specific industry momentum./nThe third chapter further explores the underlying mechanism to explain the market under-reaction to foreign information identified in the second chapter. The return predictability becomes more pronounced for smaller firms and firms with less analyst coverage, lower institutional holdings, lower fraction of foreign operations and more complicated international operations structure. I also find that stock prices respond more to foreign operations information during the month of a quarterly earnings announcement or when there is more foreign news relative to domestic news appearing in the media. In addition, information about firms' operations in Asia is delayed more than information about operations in Europe and English-speaking countries. These results are consistent with the hypothesis that news about multinational firms' foreign operations diffuses gradually, indicating investors' limited attention and processing capacity for foreign information.

Advisor: DellaVigna, Stefano
Malmendier, Ulrike
State and the Paradox of Gender Segregation in Iran

This dissertation is about state formation processes and gender segregation practices in postrevolutionary Iran. It uses gender segregation as a policy and spatial indicator to trace the shifts in state power between the establishment of the Islamic Republic (in 1979) and 2009. It explores the politics around the production of gender-segregated spaces, the imperatives of the state that produces them, and the implications for women's public presence./nBuilding on 182 interviews, more than 16 months of fieldwork between 2008 and 2011, this dissertation offers a thorough account of the (trans)formation of three major sites of gender segregation in Tehran, Iran, namely women-only parks, segregated buses, and men-only sports stadiums./nThroughout this work, I argue that current models that attribute the endurance of the Islamic Republic of Iran to its application of coercion and prohibitive measures, fail to account for the productivity of the Iranian state power. Thus, instead of dismissing the Iranian government mode of rule as that of religious totalitarianism using repression, I illustrate that it is more productive to look closely at the intricacies of power and the multitudes of their logics, in order to understand spaces, gender, Islamic rule, and subject formation./nThis dissertation contributes to theories of the state, feminist theories, and theories of urban governmentality: First, a close examination of the state's official rationales for gender segregation policies and the tensions and problems these policies address illuminates how the state continuously reconfigures its power in order to maintain its legitimacy in an increasingly globalized world with its shifting geopolitical alignments. By delineating several historically contingent shifts in gender segregation policies, I illustrate the broader shift in the Iranian state power from authoritarian sovereignty in the 1980s to disciplinary governmentality.

Advisor: Ray, Raka
Enantioselective Transformations of Carbon-Carbon Multiple Bonds Using Electrophilic Catalysts and Reagents

The activation of relatively unreactive carbon-carbon (C-C) multiple bonds is an important tool for the introduction of functional groups and stereochemical information in organic molecules. In recent years, the use of electrophilic cationic gold(I) complexes for the functionalization of alkynes and allenes has seen rapid development. An especially general application of gold catalysis is the nucleophilic trapping of gold-activated ð bond to give a heterocyclic compound. In the case of allenes, chiral ligands have been used to generate product with excellent enantiocontrol. In the first part of this Thesis we report studies on the development of an enantioselective cyclization using the gold-catalyzed transformation of propargyl esters to generate allenes in situ. A subsequent gold-catalyzed dynamic kinetic asymmetric cyclization of a phenol onto the allene resulted in the generation of enantioenriched cyclized chromanone derivatives from racemic starting material. The optimal catalyst for this transformation was a (biscarbene)digold(I) complex, which delivered better enantioselectivities than previously known phosphine-gold and phosphoramidite-gold complexes./nElectrophilic sources of the halogens (fluorine, chlorine, bromine, and iodine) activate C-C multiple bonds in much the same way as gold(I) complexes, but the electrophilic atom of the reagent is incorporated into the final product. Because halogen atoms are amenable to further functional group manipulation and are also present in complex natural products, the enantioselective synthesis of halofunctionalized products from alkenes is an important synthetic goal. Typically, enantioselectivity is achieved using a chiral catalyst to activate the electrophilic reagent. However, high enantioselectivities may be hampered by uncatalyzed background reactivity. The Toste research group has introduced a new approach for electrophilic functionalization (chiral anion phase transfer catalysis) by inducing ion pairing between a phosphate anion chiral source and a cationic electrophilic reagent by phase transfer. This concept was initially demonstrated for fluorination, using the cationic reagent F-TEDA-BF4 (Selectfluor®). In the second part of the Thesis, we report studies on the extension of this strategy to the heavier halogens. With the successful development of bromination and iodination reagents suitable for chiral anion phase transfer, we applied these reagents to the synthesis of halogenated benzoxazines with high levels of enantioselectivity.

Advisor: Toste, F. Dean
Topics in Topologically Ordered Phases of Matter

An outstanding problem in the study of topologically ordered phases is to find methods to distinguish topologically ordered from unordered phases. The topological entanglement entropy, a negative shift to the entanglement entropy scaling, has emerged as one possible distinguishing probe. The n=2 Rényi topological entanglement entropy of the triangular quantum dimer model is studied by classical Monte Carlo sampling of Rokhsar-Kivelson-like ground state wave functions, and using quantum Monte Carlo sampling for Hamiltonian parameter values away from the Rokhsar-Kivelson point. Both results demonstrate the universality of topological entanglement entropy over a wide range of parameter values within a topologically ordered phase. For systems sizes that are accessible numerically, it is found that the quantization of topological entanglement entropy depends sensitively on correlations. At the Rokhsar-Kivelson point, competing corner contributions to the entanglement entropy are also characterized./nAnother class of topologically ordered materials existing in three dimensions are topological insulators, which exhibit Dirac modes on its surface. The anomalous currents arising from these modes are investigated. The Dirac energy eigenstates are computed on a flat torus (genus one topology) and closed cap cylinder (genus zero topology) for various mass-term geometries. From the resulting properties of the surface spectra, a potential application for a flux-charge qubit is presented.

Advisor: Whaley, K Birgitta
Moore, Joel E
Excitonic Structure and Energy Transfer in Photosynthetic Pigment Protein Complexes and Their Assemblies

The research presented in this dissertation focuses on understanding how the spatial and energetic organization of pigment molecules within photosynthetic assemblies create efficient, natural light harvesting machines. In the first chapter we briefly describe photosynthetic light harvesting and explain the basic features of third-order spectroscopy and time-resolved fluorescence measurements used in this dissertation to characterize the relationship between the protein-bound pigments and their light harvesting processes. In chapter two, we start studying photosynthesis at the length scale of a single pigment-protein complex (PPC) and introduce a novel third-order frequency generation technique that is very sensitive to the excitonic structure of a PPCs. This technique is applied to a model pigment binding protein, the Fenna-Matthews-Olson (FMO) complex. In the third chapter, we propose a new approach to extracting information from optical, third-order measurements by combining chirplet transforms and shaped excitation pulses to glean information usually buried in the wings of the 2D electronic spectrum. Finally, in the fourth chapter, we consider longer length scale assemblies and treat photosystem II (PSII) supercomplexes which are composed of many individual PPCs. Using information gathered on isolated PPCs, we construct the first structure-based model of energy transfer in PSII supercomplexes to study the principles of light harvesting in functional photosynthetic machinery.

Advisor: Fleming, Graham R
Bidirectional Associations between Behavior Problems and Teacher-Child Relationship Quality in Chinese American Immigrant Children

This study examined the prospective associations between behavior problems and teacher-child relationship quality (TCRQ) in a socio-economically diverse sample of Chinese American first- and second-grade children in immigrant families (N = 258). Externalizing and internalizing problems were assessed using parents' and teachers' ratings. Teachers completed a questionnaire measuring TCRQ dimensions of Warmth and Conflict and children completed a questionnaire measuring Closeness. Path analyses were conducted to examine the bidirectional associations between behavior problems and TCRQ, controlling for baseline levels and demographic characteristics. Results indicated that teacher-rated externalizing problems negatively predicted child-rated Closeness, teacher-rated internalizing problems negatively predicted teacher-rated Conflict, and parent-rated internalizing problems negatively predicted teacher-rated Warmth. Although teacher-rated TCRQ did not significantly predict teacher-rated behavior problems, teacher-rated Conflict positively predicted parent-rated externalizing problems. Unexpectedly, child-rated Closeness also positively predicted parent-rated externalizing problems. These findings highlight the importance of assessing TCRQ and children's behavior problems using multiple reporters. The present study also provides support for the transactional relationship between children's behavior problems and TCRQ. Recommendations for school-based interventions with Chinese American children in immigrant families are discussed.

Advisor: Zhou, Qing
Understanding and manipulating electronic quantum coherence in photosynthetic light-harvesting

Ultrafast spectroscopy experiments show that photosynthetic systems can preserve quantum beats in the process of electronic energy transfer between pigments, even at room temperature. But what does this discovery imply for biology - and for quantum mechanics? This dissertation examines photosynthesis through the tools of quantum information science. We evaluate to what extent photosynthesis can be thought of as a type of quantum technology, and consider how we can apply experimental tools widely used for quantum technologies (state tomography and coherent control) to photosynthesis. Throughout, we use the Fenna-Matthews-Olson (FMO) complex of greens sulfur bacteria as a model photosynthetic pigment-protein complex./nIn Part I, we evaluate two mechanisms for the possible biological relevance of quantum coherent motion. First, we consider the extent to which dynamics in light-harvesting systems exhibit the quantum speedups characteristic of quantum algorithms and quantum walks. Second, we demonstrate a ratchet effect in electronic energy transfer enabled by partially coherent dynamics. To do so, we build a new model of energy transfer between weakly coupled light-harvesting complexes to understand how electronic coherence arises under natural conditions./nIn Part II, we present proposals for experimental probes of light harvesting dynamics with ultrafast spectroscopy. We show how the signal from pump-probe spectroscopy can be formally inverted to determine the excited state electronic density matrix. Finally, we examine the feasiblity of coherent control experiments on light-harvesting systems, and provide two realistic targets feasible with present-day technology.

Advisor: Whaley, K. Birgitta
Moore, Joel E.
Dynamics and Stability of Rolling Viscoelastic Tires

Current steady state rolling tire calculations often do not include/ntreads because treads destroy the rotational symmetry of the tire./nWe describe two methodologies to compute time periodic/nsolutions of a two-dimensional viscoelastic tire with treads:/nsolving a minimization problem and solving a system of equations./nWe also expand on work by Oden and Lin on free spinning rolling elastic tires/nin which they disovered a hierachy of $N$-peak steady state standing wave solutions./nIn addition to discovering a two-dimensional hierarchy of standing wave solutions that/nincludes their $N$-peak hiearchy,/nwe consider the effects of viscoelasticity on the standing wave solutions./nFinally, a commonplace model of viscoelasticity used in our numerical experiments/nled to non-physical elastic energy growth for large tire speeds./nWe show that a viscoelastic model of Govindjee and Reese remedies the problem.

Advisor: Wilkening, Jon
Power, Performance and Bias: Evaluating the Electoral Quotas for Scheduled Castes in India

Many countries make special institutional arrangements to guarantee the political representation of minorities. This is usually justified as a way of reducing ethnic tensions and improving the quality of democratic representation. In addition, it is often assumed that minority representatives will act in the interest of their group. India has had reserved seats for the Scheduled Castes (SCs, the former `untouchables') in their state assemblies since independence. Reserved constituencies are single member districts where only SCs can run for election, while the whole population votes for them irrespective of their caste group. In this dissertation I explore the effects of these quotas between 1974 and 2007. I am able to control for the selection bias inherent in quotas being non-randomly assigned in the 1970s by matching more than 3,000 constituencies on pre-treatment variables from 1971. Using unique new data at the constituency-level for 15 Indian states, I show that the quotas have been effective at guaranteeing the political presence of SCs and integrating them into main-stream politics. Contrary to the bias often reported against SC politicians, they are not much different from other politicians: they represent similar parties, have similar rerunning patterns, and hold many cabinet positions. In fact, rather than being spokespersons of the SC community, SC politicians seem to be agents of their parties rather than agents of their group. The presence of SC politicians seems to have had positive effects on caste bias in society at large, though, with voters in reserved areas reporting less caste discrimination than voters in non-reserved areas. Considering how strong the social boundary of untouchability used to be in Indian society, this can be seen as a huge achievement in itself. But the integration of SC politicians, and the fact that they are answerable to mostly non-SC voters, also means that their presence has not done much to improve the substantive representation of SC interests. This can therefore serve as a reminder that there are clear trade-offs in institutional design and that an electoral system might work well to reduce social bias and prevent conflict without improving the substantive representation of minority groups.

Advisor: Chhibber, Pradeep
Aerial Righting, Directed Aerial Descent, and Maneuvering in the Evolution of Flight in Birds

This thesis consists of four major studies: a study of incipient flight behaviors in young birds over ontogeny (chapter 1); a detailed study of maneuvering using physical models of a likely ancestral bird morphology (chapter 2); a comparative study of maneuvering ability in several stem-group birds, within a phylogenetic context (chapter 3); and development of basic engineering theory to quantify the turbulence sensitivity of shapes to environmental turbulence of given scales and spectral content. The studies have identified: 1) shifts in function from asymmetric to symmetric movements in young birds, contrary to predictions from alternative hypotheses and occurring before wing-assisted incline running; 2) shifts in function, tied to angle of attack, of asymmetric appendage postures in creating yawing and rolling moments; and 3) migration of control effectiveness as tails are shortened and other features change, during the early evolution of birds. The work plugs some considerable gaps in current prevailing theories (e.g. Dial, 2003; Tobalske et al., 2011) and provides a test of hypotheses of flight evolution not based in outdated "trees-down'' or "ground-up'' paradigms from the past, but rather based on the universal need of airborne animals to maneuver (Dudley and Yanoviak, 2011; Maynard-Smith, 1953)./nThis work seeks to understand early flight evolution from a maneuvering perspective; every animal in the air must maneuver, and by understanding "powered'' flight as simply a point along a spectrum of maneuvering flight (Dudley and Yanoviak, 2011), unifying breakthroughs are made. It is hoped that the multifaceted approach taken here, with ontogenetic series, aerodynamic studies, and phylogenetic approaches, is robust against the shortcomings of any one approach individually: confounding ontogeny with evolution (as may be the case in others' studies of alternative hypotheses, e.g. Dial, 2003); inferring implausible functions from paleontological material in the absence of proper benchmarking against live animals; or misdiagnosis of how forms work in the absence of functional studies.

Advisor: Dudley, Robert