VictorJuiz/thesis huggingface dataset:
Measurements of the Flavor Composition and Inelasticity Distribution of High-Energy Neutrino Interactions in IceCube

At the IceCube Neutrino Observatory, neutrino interactions are observed across a broad energy range extending from ~ 5 GeV to ~ 1 PeV. Above ~ 100 TeV, neutrinos primarily originate from distant astrophysical objects whose identity is yet unknown. At lower energies, most neutrinos result from cosmic-ray interactions in Earth's atmosphere. In this work, two studies of contained neutrino interactions in IceCube are presented./nIn the first study, three years of IceCube data recorded from May 2010 to May 2013 are analyzed to measure the flavor composition of astrophysical neutrinos in the energy range from 35 TeV to 1.9 PeV. The flavor composition is found to be consistent with the ratio of ~ (1/3 : 1/3 : 1/3) expected from the oscillation of neutrinos produced by complete pion decay in distant astrophysical sources. Limits are placed on non-standard flavor compositions that could arise in exotic physics scenarios. The energy spectrum of astrophysical neutrinos is also measured and is well-described by a falling power law with index 2.6+-0.15./nIn the second study, five years of IceCube data from May 2011 to May 2016 are analyzed with improved background rejection and event classification techniques, and the inelasticity in charged-current muon neutrino interactions is reconstructed. Improved limits on the flavor composition of astrophysical neutrinos are obtained, and there is consistency with the expected flavor ratio of ~ (1/3 : 1/3 : 1/3). Additionally, the energy spectrum of astrophysical neutrinos is found to be consistent with a power-law with index 2.62+-0.07 in the energy range from 6.6 TeV to 2.2 PeV. Limits are placed on a power-law flux from a second population of astrophysical sources that may explain the harder power-law index of 2.13+-0.13 found in an IceCube analysis of up-going muons at higher energies./nThe inelasticity distribution of charged-current muon neutrino interactions is also obtained and is found to be consistent with the calculation of Cooper-Sarkar et al. across an energy range from 1 TeV to 100 TeV. The inelasticity distribution can also be used measure the neutrino to antineutrino ratio of the atmospheric neutrino flux. A scaling factor on the muon neutrino to antineutrino flux ratio calculated by Honda et al. is found to be 0.77+0.44-0.25 in the energy range from 770 GeV to 21 TeV. Lastly, the inelasticity distribution can also be used to perform an indirect search for charged-current charm production by neutrinos. Assuming a leading-order calculation of the inelasticity distribution for charm production events, zero charm production can be excluded at 91% confidence level in the energy range from 1.5 TeV to 340 TeV. In the future, it is expected that the techniques developed for this analysis can be applied to search for neutrino interactions beyond the Standard Model in IceCube and next-generation neutrino telescopes.

Advisor: Klein, Spencer R
Applications of Toric Geometry to Geometric Representation Theory

We study the algebraic geometry and combinatorics of the affine Grassmannian and affine flag variety, which are infinite-dimensional analogs of the ordinary Grassmannian and flag variety. In particular, we analyze the intersections of Iwahori orbits and semi-infinite orbits in the affine Grassmannian and affine flag variety. These intersections have interesting geometric and topological properties, and are related to representation theory./nMoreover, we study the central degeneration (the degeneration that shows up in local models of Shimura varieties and Gaitsgory's central sheaves) of semi-infinite orbits, Mirkovic-Vilonen (MV) Cycles, and Iwahori orbits in the affine Grassmannian of type A, by considering their moment polytopes. We describe the special fiber limits of semi-infinite orbits in the affine Grassmannian by studying the action of a global group scheme. Moreover, we give some bounds for the number of irreducible components for the special fiber limits of Iwahori orbits and MV cycles in the affine Grassmannian. Our results are connected to Gaitsgory's central sheaves, affine Schubert calculus and affine Deligne-Lusztig varieties in number theory.

Advisor: Nadler, David
Photon upconversion improvements via molecular antenna and their applications

The efficient conversion of low-energy, near-infrared (NIR) photons to higher energies promises advancements across a range of disparate fields, from more efficient solar energy capture to advanced biologic studies and therapies. At the forefront of this effort, upconverting nanoparticles (UCNPs) contain an array of lanthanide ions alloyed into a ceramic matrix, most commonly NaYF4. These lanthanide ions possess a 4f orbital manifold with a series of ladder-like, long-lived electronic states, allowing the sequential absorption of NIR photons at relatively low photon flux. The electrons climb the 4f Stark levels, absorbing multiple photons from the excitation source before relaxing back to the ground state upon emission of a photon with an energy higher than those from the source. While UCNPs are among the most efficient systems for converting NIR light to visible, they still hold key limitations, namely, they only weakly absorb incoming photons, hindering their external quantum efficiencies and overall performance./nThis thesis presents studies designed to enhance the efficiency and brightness of UCNPs. One method to circumvent the inherently weak absorption in UCNPs involves attaching organic dye antennae to the surface of the nanoparticles to absorb incoming light and funnel the absorbed energy into the UCNP. However, a detailed understanding of the energy transfer mechanism between dye and UCNP is required to fully realize the potential of this system. We propose, using a series of spectroscopic and kinetic measurements, that this energy transfer is mediated via the absorbing dye triplet state, and further that the intersystem crossing rate within the dye is enhanced by interactions with the heavy nuclei of the lanthanides within the UCNP. We then design a highly efficient dye:UCNP hybrid system utilizing this new understanding. Lastly we present a study highlighting the power and potential of using UCNPs for biological applications. Together these studies will advance the utilization of photon upconversion towards realizing its promise in applications.

Advisor: Schuck, Peter J.
Somorjai, Gabor A.
Consistency and Discrepancy Analysis of Human Walking

As the trend for wearable bioinformatic sensors continues to increase, researchers pursue integrating knowledge of the human body into the design of a simpler sensory system. By observing the consistency and discrepancy of human behavior, insight can be gained on how to design a monitoring architecture and what content to monitor. Because no two human individuals are identical, it is important to capture consistency among people based on an all-inclusive understanding. The first step of monitoring is to quantify the behavior. Because there is a limitation to a commercial motion capturing system, a durable sensory system, the Smartshoe, is designed to remotely record and measure ground contact force (GCF). The recorded data is locally processed by the hardware’s computing unit and a non-blocking software architecture regulates the data rate of the recording. The accuracy and repeatability of GCF measurements with the piezoelectric sensor are demonstrated. The detailed schematic design is also explained in the text. A graphical user interface (GUI) is designed to show the real-time applicability of the software./nAn optimal sensor location consistently differentiates distinct human movements and requires a minimal usage of the computational resource. Drawing inspiration from L1 regularization in classification problems, the use of feature selection results is an optimal sensor layout for gait phase estimation. The method reveals the significant sensor location involving in the classification and filters out the redundant locations. As a consequence of this optimization, the input complexity is greatly reduced. The results resemble some of the previous choices but also eliminate some redundancy. The estimators' performance of the optimized layout and the anatomic layout are compared and there is no significant disagreement./nFinally, a two-level hierarchical decision framework is proposed for a comprehensive representation of human bipedal behavior. The method decouples behavior identification to two levels, discrete modes and mode-dependent special tasks. The double-peaked GCF pattern is used as a metric to distinguish walking mode from running mode. Support vector machine (SVM) with a moving window is implemented to identify the discrete modes in the first level. In the second level, the mode-dependent tasks are defined under single or multiple modes. In walking mode, a set of two-sided fuzzy logic rules is utilized for robustly recognizing the gait phases. The speed of walking is also estimable by observing the peak-to-valley ratio in the GCF pattern. The diagnosis of touch-based symptoms, on the other hand, are dual-mode specific tasks. Plantar Fasciitis causes a smaller Mid-Stance to Terminal Stance ratio in combination with asymmetric running GCF pattern in the affected side. And finally, the combined performance using the framework shows a robust and accurate analysis of human walking behavior.

Advisor: Tomizuka, Masayoshi
Continuous paths in Brownian motion and related problems

This thesis is composed of six chapters, which mainly deals with embedding continuous paths in Brownian motion. It is adapted from two publications \cite{PT15a, PT15b}, joint with Jim Pitman./nWe ask if it is possible to find some particular continuous paths of unit length in linear Brownian motion. Beginning with a discrete version of the problem, we derive the asymptotics of the expected waiting time for several interesting patterns. These suggest corresponding results on the existence/non-existence of continuous paths embedded in Brownian motion./nBy various stochastic analysis arguments (path decomposition, It\^{o} excursion theory, potential theory...), we are able to prove some of these existence and non-existence results:/n\begin{center}/n\begin{tabular}{| c | c | c | c | c |}/n\hline/n$Z$ & $e$ & $V(b^{\lambda})$ & $m$ & $R$ \ \hline/nEmbedding into $B$ & No & No & Yes & Yes \ \hline/n\end{tabular}\/n\end{center}/nwhere $e$ is a normalized Brownian excursion, $V(b)$ is the Vervaat transform of Brownian bridge ending at $\lambda$, $m$ is a Brownian meander, and $R$ is the three dimensional Bessel process of unit length./nThe question of embedding a Brownian bridge into Brownian motion is more chanllenging. After explaining why some simple or traditional approaches do not work, we make use of recent work of Last and Thorisson on shift couplings of stationary random measures to prove the result. These can be applied after a thorough analysis of the Slepian zero set $\{t \geq 0; B_t = B_{t+1}\}$./nWe also discuss the potential theoretical aspect of embedding continuous paths in a random process. A list of open problems is presented.

Advisor: Pitman, James
Essays in Industrial Organization and Behavioral Economics

This dissertation is comprised of two essays at the intersection of Empirical Industrial Organization and Behavioral Economics. They explore how business decisions are more richly explained with additions in psychological insights commonly found among consumers. These behavioral biases can affect a firm's decision to participate and their supply in the market, ultimately impacting market competition, supply thickness, and equilibrium./nIn Chapter 1, I explore how retailers make entry and exit decisions in the context of an online marketplace. Using a rich panel of internal data from eBay on dedicated sellers, I analyze a feature of the platform requiring sellers to select among monthly contracts that differ in the listing fee schedules. I further exploit a regime change that introduced a monthly allowance of free listings of inventory, altering all contracts from a two-part tariff to a three-part tariff design. This design change was effective in attracting new users and sellers to the platform, encouraging experienced users to become high-volume sellers, and increasing total inventory listed in the marketplace. This is despite little changes in average costs of selling. I demonstrate that standard entry and exit models cannot explain this increase in supply and competition. Instead, I propose loss aversion as an additional factor impacting participation./nChapter 2 investigates how high-volume, experienced retailers value their products and make supply decisions. Using similar data from eBay and exploiting the same contract feature and policy change, I analyze both the sellers’ contract choice decisions and the timing of product listings. By estimating a dynamic model of plan choice and listing decisions, I find that sellers have a limited learning period and hold biased beliefs on the option values of their products. Furthermore, they respond heterogeneously to dynamic incentives and future listing costs, leading to an uneven supply of products on the platform. Using the model estimates, I show that debiasing sellers would increase seller surplus by 6\% but decrease platform listing revenue by 26%. However, since many platforms generate the majority of revenue from percentage fees on the listings' values, they may prefer to pursue policies that increase total listings. By targeting specific sellers, such policies can increase aggregate listings on the platform by up to 4.8% at a loss of 5.5% in listing revenue.

Advisor: DellaVigna, Stefano
Handel, Benjamin
Ancillary Citizenship and stratified Assimilation: How American Indian Education was developed to force American Indians into the United States economy as reserve laborers

Abstract/nAncillary citizenship and stratified assimilation: How American Indian Education was developed to force American Indians into the United States economy as reserve laborers/nby Kimberly Richards/nDoctor of Philosophy in Ethnic Studies/nUniversity of California, Berkeley/nProfessor Thomas Biolsi, Chair/nIn 1933, the newly appointed director of Education for the Indian Service, Dr. William Carson Ryan, the director of Extension and Industry, A.C. Cooley, and R.M. Tisinger, State Supervisor of Indian Education of Arizona, took a tour of four Mexican States on behalf of the Bureau of Indian Affairs. This trip was to assess the school systems the Mexican government had been implementing in rural indigenous communities. It was especially enticing for these progressive educators, given that the director of the program was none other than Dr. Moises Saenz, a student of John Dewey. What was it about this rural school program that was so enticing to these three men? As lead investigator of the educational section of the Meriam report, Ryan had advocated for a more progressive form of education, one that would utilize the child’s surrounding community and environment as a integral part of the learning process. However, just as Indian educational models had done in the past, progressivism, as it would be used for Native students as well as racialized minorities and newly arrived immigrants, was deeply entrenched in liberal protestant American values, norms and beliefs./nIn order to understand the trajectory of progressive education as it was thought to apply to Indian students, it is important to gauge the dialogue and rhetoric surrounding the transition. With this research in mind this dissertation aims to reconstruct and question the policies, practices and motivations that enabled the BIA to maintain a long-standing assimilation policy through schooling. In particular this dissertation asserts that rather than shifting policy towards an ambitious liberal agenda of cultural acceptance, the union of policy makers and educators of the progressive era further entrenched the assimilation project./nYet, only a handful of scholars have focused their analysis on the progressive era, and an even smaller cohort has been able to illuminate the longer assimilation trajectory of Indian education and BIA aspirations. This dissertation adds to this small body of work in part by arguing that the purpose of Indian schooling was to incrementally force Native peoples into American intuitions, not to usher in a new era of cultural pluralism or acceptance. Moreover, the initial steps of this assimilation educational policy, which were focused on creating a reserve labor force of ancillary citizens also laid the foundation for mid-twentieth century BIA Relocation efforts.

Advisor: Biolsi, Thomas
Changing Environments, Social Adaptations, Divergent Trajectories: The Application of Socio-Natural Systems Thinking and Geospatial Modeling to the Late Bronze/Iron Age Transition in West-Central Syria, ca. 1350-750 BCE

The transition for the Late Bronze to the Iron Age in the Eastern Mediterranean is still only incompletely understood, with explanations ranging from social disintegration to environmental degradation. Especially the idea of societal collapse has had a strong influence on this discourse and continues to be frequently invoked as an explanatory model, despite recent advances in the historical and archaeological understanding of this transitional period. Mediated by Classical Greek and biblical tradition, this ongoing appeal of collapse theory can be attributed to the (overt or subliminal) persistence of 18th-20th century CE intellectual paradigms, which are often enmeshed with ill-defined concepts of race, ethnicity, or social evolution. In the context of the Late Bronze/Iron Age Levant, traditional applications of collapse theory reveal more about Western scholarly self-perceptions, than they contribute to an understanding of this critical period./nThis dissertation argues that Socio-Natural Systems (SNS) thinking, borrowed from ecology, offers a theoretical and methodological framework with which the Late Bronze/Iron Age transition can be analyzed and understood in more detail. Rather than relying on incompletely understood and ultimately restrictive classificatory labels, SNS thinking promotes the analysis of processes of change across multiple scales, both temporal and geographic. SNS analysis acknowledges the interrelatedness of social processes and environmental conditions, and provides a structure through which the interactions between societies and their respective environments can be studied./nThe principles of SNS analysis are applied to a study region in Western Syria and Northern Lebanon, termed West-Central Syria, in a preliminary analysis of socio-natural interactions in the late 2nd and early 1st millennia BCE. Geospatial analysis is used not only to investigate and quantify relationships between social and environmental processes, but also to overcome significant gaps in current data availability. GIS modeling is used to retrodict climatic conditions in the late 2nd and early 1st millennia BCE, but also to develop a predictive model of agricultural suitability, enabling the analysis of the effects of climatic change on the environment and ancient agricultural economies. Combining the results of these models with geostatistical analysis, palaeoenvironmental data, and the historical and archaeological record, this dissertation argues that processes of change and transformation in Late Bronze/Iron Age West-Central Syria were geographically and chronologically specific, and conditioned on a highly complex interplay of both social and environmental factors.

Advisor: Porter, Benjamin
Feldman, Marian
Spatially Resolved Charge Transfer in Molecular Nanostructures at the Surface of Gate Tunable Graphene Devices

The ability to modify the electronic properties of monolayer graphene via charge-donating or charge-accepting molecules creates new opportunities for fabricating nano-scale hybrid devices. Introducing donor and acceptor molecules to a graphene surface induces charge transfer and creates localized Coulomb potentials. Combined with an electrostatic back-gate on a graphene/BN device, it is possible to engineer a variety of electrostatic potentials for studying fundamental electronic phenomena. In this dissertation, we discuss local probe investigation of such phenomena in graphene/molecule hybrid systems using scanning tunneling microscopy and atomic force microscopy./nWe first describe the procedures for fabricating atomically clean graphene/BN field effect transistors (FETs) for molecular self-assembly and local probe studies. Using these graphene/BN FETs, we are able to adjust the energy alignment of aromatic molecular orbital levels with respect to the Fermi level. These molecules are weakly coupled to the graphene and show clear vibronic resonances in their energy spectra. By choosing a more electronegative molecule, fluorinated TCNQ, with orbital levels closer to the Dirac point, we are able to demonstrate charge-state switching in single molecules. The electric field-induced energy shift of the molecular levels is influenced here by gate-dependent screening effects arising from the graphene substrate. Additionally, we find that inert fatty acid islands deposited on the surface can help to stabilize single molecules for local probe characterization./n/nSuch control of single molecules on a device surface allows us to create more complex self-assembled molecular nanostructures using bottom up techniques. Inert fatty acid islands, for example, are used to act as a template for the self-assembly of one-dimensional molecular arrays. These arrays are electrically charged by applying an electrostatic back-gate to the graphene/BN FET, thus generating strong one-dimensional Coulomb potentials. Such Coulomb potentials are found to induce new localized Dirac fermion states. The formation of these states are explained by an atomic collapse picture whereby an electron cannot form stable bound states around an isolated Coulomb potential, but rather spirals inward toward the center of the impurity. Self-assembly processes also lead to the formation of densely-packed, charged two-dimensional molecular islands on the graphene surface. The formation mechanism of these islands is explained by work function heterogeneity on the surface, a mechanism unique to poorly screened substrates like graphene. This work reveals new fundamental behavior for Coulomb potentials anchored to graphene surfaces at different length scales and geometries, enabling the engineering of 2D potential landscapes and electron wave-functions in graphene devices.

Advisor: Crommie, Micheal F