VictorJuiz/thesis huggingface dataset:
Pathways for progress toward universal access to safe drinking water

Over two billion people globally lack access to safe water. This is both a public health problem and a violation of human rights. The United Nations Sustainable Development Goals, through its ambitious and human-rights based framework, and the safe water, sanitation, and hygiene (WASH) community, through its calls for "transformative WASH," have signaled that status quo interventions will not achieve universal safe water access goals. Rather, there is a need for new pathways toward the progressive realization of the human right to available, safe, acceptable, accessible, and affordable water for all. In Chapter 1, I present the results of a systematic review of adherence to chlorine point-of-use (POU) water treatment at the household-level, a widely promoted and inexpensive strategy for improving drinking water quality and health. While centralized chlorination of urban piped water supplies has historically contributed to major reductions in waterborne illness, sub-optimal adherence to household-level water treatment indicates that chlorine POU products are unlikely to lead to the widespread public health benefits associated with centralized treatment of piped water supplies. In Chapter 2, I present the results of an evaluation of system-level, passive chlorination technologies in small water systems in rural Nepal. These passive chlorination technologies have the potential to automatically treat water, without requiring the household-level behavior changes that are required for POU products. While these technologies have been rigorously evaluated as decentralized treatment solutions in some urban settings, little data exist on their performance in remote, rural systems, for which these technologies can serve as fully centralized chlorination systems. Over one year, we found that these technologies significantly improve the quality of water accessed by households. While service delivery models should be explored to ensure long-term sustainability, passive chlorination technologies have the potential to radically improve how rural households gain access to safe water. In Chapter 3, I present a synthesis of the literature at the intersection of gender and domestic water. The vast water and health literature is overwhelmingly focused on the consequences for child health, while focusing less attention on the health of the water carriers and managers, the women and girls who are typically the implementers of household-level treatment strategies. Yet, failing to understand the full consequences for women and girls leaves a major gap in our accounting of the value of accessible and safe water and cannot lead to gender equality.

Advisor: Ray, Isha
Valuations of Polyhedra and Coxeter Combinatorics

Discrete geometry is a field of mathematics which encompasses the study of polyhedra, or intersections of closed half-spaces in some vector space. Algebraic combinatorics employs algebraic methods to learn about combinatorial objects. This thesis lies at the intersection of these two fields and traverses back and forth between them. We use algebra to prove results about polyhedra, and use polyhedral geometry to classify functions that are of interest in algebraic combinatorics. It is divided into four chapters: an introduction, and three sections of original results which each use different algebraic techniques./nIn the first chapter, we provide some background on polyhedra and establish the main actors of this thesis, generalized permutahedra. Along the way we introduce orbit polytopes and matroids as examples, and we also show how the combinatorics of generalized permutahedra can be extended to arbitrary finite reflection groups to obtain generalized Coxeter permutahedra and Coxeter matroids. We further give some background on combinatorial Hopf monoids, Ehrhart theory, and valuations that hints at the various approaches explored in this thesis./nIn the second chapter, we introduce the Hopf monoid of orbit polytopes, which is generated by the generalized permutahedra that are invariant under the action of the symmetric group. We show that modulo normal equivalence, these polytopes are in bijection with integer compositions. We interpret their Hopf structure through this lens, and we show that applying the first Fock functor to this Hopf monoid gives a Hopf algebra of compositions. We describe the character group of the Hopf monoid of orbit polytopes in terms of noncommutative symmetric functions, and we give a combinatorial interpretation of the basic character and its polynomial invariant./nIn Chapter 3, we explore equivariant Ehrhart theory, a generalization of Ehrhart theory introduced by Stapledon that counts the lattice points in a polytope up to the action of some symmetry group. We describe the equivariant Ehrhart theory of the permutahedron, and we explore the relationship between the properties of its equivariant Ehrhart series and the permutahedral toric variety. Answering a question of Stapledon, we describe the equivariant Ehrhart theory of the permutahedron, and we prove his Effectiveness Conjecture in this special case./nIn the last chapter, we give the universal valuative invariant of Coxeter matroids. In the process, we also describe the universal valuation of generalized Coxeter permutahedra. This chapter builds off of prior work of Derksen and Fink, but many of their techniques do not apply to the Coxeter setting, requiring new methods to extend their results. We borrow tools from the theory of 0-Hecke algebras to establish properties of Coxeter Schubert matroids.

Advisor: Ardila, Federico
Srivastava, Nikhil
Statistical methods for causal inference fromsequentially collected data and sequential decisionmaking

I consider the type of statistical experiment commonly referred to as adaptive trials, in which the experimenter interacts with an individual or a set of individuals, and, sequentially, over time steps $t=1,\ldots,T$, observes a vector of measurements $L_1(t)$ on the individual or individuals, then assigns treatment vector $A(t)$, and then observes a post-treatment vector of measurements $L_2(t)$. In an adaptive trial, the experimenter can update the treatment distribution at $t$ based on previous observations./nThis very general formulation covers many common settings such as dynamic treatment regimes, the stochastic contextual bandit model, the Markov Decision Process model in reinforcement learning. I consider two related types of learning tasks: causal inference from data collected under an adaptive trial, and sequential decision making with the objective of either maximizing the sample efficiency for an estimation task, or of minimizing some form of cumulative regret./nMy primary concerns are to develop statistical methods and algorithms that use statistical models that assume no more than is known from domain knowledge (and therefore are nonparametric), and that are as sample efficient as possible.

Advisor: van der Laan, Mark J
Neural Circuits and Hormonal Mechanisms Underlying Female Reproduction

‘Homeostasis’ is the physiological process of maintaining a stable equilibrium, operating within optimal limits to promote health and prevent illness. Deviations from homeostasis can have adverse consequences for one’s health. However, physiological and behavioral needs vary markedly over the course of the day, necessitating that biological systems are adjusted correspondingly. Likewise, physiological needs change over the female reproductive cycle, with ovulation, pregnancy and fetal development, and parturition requiring specifically-timed patterns of hormone secretion regulated by the circadian system. Disruption to homeostasis, either by circadian misalignment or by exposure to stress, has marked, negative consequences for female reproductive health, including ovulation, pregnancy success and maintenance, and offspring development. The overarching goal of this dissertation research is to understand the neural and hormonal mechanisms underlying reproductive health and how these mechanisms are affected by disruption to homeostasis through circadian misalignment and stress. This dissertation considers two aspects of the female reproductive cycle, the ovulatory cycle and pregnancy. Despite a significant volume of knowledge detailing the circadian regulation of ovulation and the negative impact of stress of reproductive health, the mechanisms underlying these events remain poorly understood. Chapter 2 investigates the time-dependent sensitivity of the reproductive axis to the inhibitory neuropeptide RFamide-related peptide-3 (RFRP-3) in the control of the neuroendocrine events required for ovulation. Chapters 3-5 explore how stress hormones act on the brain, ovaries, and placenta to compromise pregnancy success and fetal development. These studies inform our understanding of the complex neural and endocrine networks regulating environmental and physiological processes involved in promoting female reproductive health.

Advisor: Kriegsfeld, Lance J
Cooperation, Competition and Specialized Metabolism in a Simplified Root Nodule Microbiome

Microbes occupy diverse habitats, forming interconnected, dynamic communities. Microbiomes associated with various plant structures often contain members with the potential to make specialized metabolites, e.g. molecules with antibacterial, antifungal, or siderophore activities. However, when and where microbes associated with plants produce specialized metabolites, and the potential role of these molecules in mediating intra-microbiome interactions, is not well understood. Root nodules of legume plants are organs devoted to hosting symbiotic bacteria that fix atmospheric nitrogen and have recently been shown to harbor a relatively simple accessory microbiome containing members with the ability to produce specialized metabolites in vitro. Based on these observations, we sought to develop a model nodule microbiome system for evaluating microbial specialized metabolism in planta. Starting with an inoculum derived from field-grown Medicago sativa nodules, serial passaging through gnotobiotic nodules yielded a simplified accessory community composed of four members: Brevibacillus brevis, Paenibacillus sp., Pantoea agglomerans, and Pseudomonas sp.. Some members of this community exhibited clear cooperation in planta, while others were antagonistic and capable of disrupting cooperation between other partners. Using matrix-assisted laser desorption/ionization imaging mass spectrometry, we found that metabolites associated with individual taxa had unique distributions, indicating that some members of the nodule community were spatially segregated, accounting for their ability to co-exist. Finally, we identified two families of molecules produced by B. brevis in planta as the antibacterial tyrocidines and a novel set of gramicidin-type molecules, which we term the britacidins. Collectively, these results indicate that in addition to nitrogen fixation, legume root nodules are likely also sites of active antimicrobial production.

Advisor: Traxler, Matthew F
A Systematic Study of the Muscle Force–Deformation Relationship at the Human Elbow: Toward Physiology-Aware Assistive Device Control and Noninvasive Muscle Force Sensing

While there exist a number of mechanically sophisticated exoskeletons, prostheses, and assistive robots, with articulations similar to those of the intact human arm and hand, these devices remain limited in their ability to augment human dexterity and safely interact with human users and collaborators. In particular, due to the limits of conventional sensing, robots remain locked in industrial cages, prosthesis users can often modulate only a single degree of freedom, and when human–device interactions do occur, we have almost no understanding of the resulting physiological impacts on the user's musculoskeletal system./nThis thesis begins to address these dual problems of device capability and safety by leveraging a novel signal class — muscle deformation, as measured via ultrasound — to probe individual muscle forces, which cannot in general be measured noninvasively but are key to understanding musculoskeletal dynamics during dexterous motion. Using the elbow flexion motion as a case study, this document describes first, preliminary characterization of this deformation and its relationship to output force; second, proof-of-concept use of this signal for a trajectory tracking task; third, collection of a comprehensive 3D deformation data set to systematically examine the force–deformation relationship; fourth, initial geometric analysis of this data set and a proposed framework for future modeling; and lastly, a discussion of the open-source release of code and data associated with this project, preliminary work on alternative sensing modalities, and speculation on future applications in robotics and medicine. This dissertation work — collectively released as the OpenArm project for collaborative research use at https://simtk.org/projects/openarm — paves the way for future investigation on both the extraction of multiple independent signals for high-dimensional device control and enhanced overall understanding of the joint human–machine dynamical system.

Advisor: Bajcsy, Ruzena
Mathematical Modeling of Human Learning and Decision Making

Reinforcement learning (RL) has been widely used to study and model human, animal and artificial intelligence. In this thesis, we focus on modeling human learning and decision making, and exemplify two ways mathematical RL modeling can add to our existing knowledge of human cognition: (1) provide a quantitative tool for parametrizing individual differences in human behavior, and (2) augment existing models to account for complex multi-step human learning.

Advisor: Pitman, Jim
Collins, Anne GE
On The Anomalous Conductivity of Low Permittivity Electrolytes Used in Electrochemical Applications

Most of the battery electrolyte candidates for multivalent-ion systems (e.g. Mg, Ca) present interesting physicochemical properties. In these are included anomalous conductivity, where molar conductivity increases with salt concentration. This phenomenon is related to the electrochemical performance and electrolyte viability. In this thesis, this phenomenon is explained via understanding and quantification of the strong inter-ionic interactions in solution. To this end, computational methods including classical molecular dynamics and electronic structure methods are combined with dielectric relaxation spectroscopy measurements. Two cases studies with ether based electrolytes, one with MgTFSI2 salt and one with Ca(BH4)2 are undertaken. In both cases, the anomalous conductivity originates from changes in salt speciation, i.e. changes in the population of distinct chemical species formed by the ions in the solution. A larger fraction of ionic salt species are promoted at higher salt concentration at the expense of larger, associated clusters. Moreover, it is found that the increase in dielectric constant with increasing salt concentration, due to a significant fraction of polar associated salt species, is likely one of the thermodynamic driving forces for this effect. The findings here are important for the rational design of multivalent electrolytes for electrochemical applications, and help inform salt and solvent selection for advanced electrolyte formulations.

Advisor: Persson, Kristin A.
Essays in Venture Capital, Reputation and Learning

In chapter 1, I study the experimentation dynamics of a decision maker (DM) in a two-armed bandit setup ([5]), where the agent holds ambiguous beliefs regarding the distribution of the return process of one arm and is certain about the other one. The DM entertains Multiplier preferences à la [27], thus I frame the decision making environment as a twoplayer differential game against nature in continuous time. I characterize the DM’s value function and her optimal experimentation strategy that turns out to follow a cut-off rule with respect to her belief process. The belief threshold for exploring the ambiguous arm is found in closed form and is shown to be increasing with respect to the ambiguity aversion index. I then study the effect of provision of an unambiguous information source about the ambiguous arm. Interestingly, I show that the exploration threshold rises unambiguously as a result of this new information source, thereby leading to more conservatism. This analysis also sheds light on the efficient time to reach for an expert opinion. The results of this chapter has been recently published in [61]./nIn chapter 2, I introduce a dynamic model of random search where ex ante heterogeneous venture capitalists (investors) with unknown abilities match with a variety of startups (projects). There is incomplete yet symmetric information about investors’ types, whereas the projects’ types are publicly observable to all investors. In the unique stationary equilibrium, the matching sets, value functions and steady state distributions are endogenously determined. Interpreting the market posterior belief about the venture capitalists’ ability as their reputation, I study the outcomes of the economy when the success or failure of the projects create feedback effects: innovation spillovers and reputational externalities. When there are positive spillovers from successful early stage projects to late stage business opportunities, I show increased levels of search frictions could save the market from breakdown caused by the neglect of spillover effect. When the reputational externality is at play, namely when the deal flow of each investor is inversely impacted by the distribution of other investors’ reputation, I show the proportion of the high ability inactive investors is inefficiently high, and the projects suffer from early termination.

Advisor: Anderson, Robert M
Modeling and Design of Nanoscale Ferroelectric and Negative-Capacitance Gate Transistors

Integration of Hf-based ferroelectric materials into the MOSFET gate stack introduces new physics that potentially enables continued scaling for both CMOS and memory devices. The electrostatic potential amplification effect arises when the device is engineered to depolarize and hence stabilize the ferroelectric negative capacitance state, which eliminates the ferroelectric hysteresis and enhances the gate control. On the other hand, when the ferroelectric layer is thick enough to overcome the depolarization field, non-volatile memory function can be realized through the remnant polarization states. Such systems exhibit process and structural compatibility with CMOS technology and thus are of significant application relevance. Experiments have demonstrated low-voltage operations for both types of devices, showing promising prospects for next-generation logic devices with high reliability./nTo harness the effects for designing the NCFET and FeFET devices, it is important to understand the behaviours of the ferroelectric layer in the relevant states. In this dissertation, the polarization responses of negative capacitance states are modeled from different aspects through self-consistent device and circuit models that are calibrated to experimental measurements. First, the 101-stage ring oscillator consisting of 14 nm FinFET devices with a ferroelectric gate layer that exhibits negative capacitance are used to study the response speed of the negative capacitance effect. The consistency of the device DC characteristics and the circuit oscillations with less than 10ps per-stage delay confirm the fast negative capacitance response. Next, NCFET device characteristics and scaling trends that are unexpected by conventional theory were explained with non-linear negative capacitance responses as described by the Landau's phenomenology. Design insights are drawn, and the observation bodes well for extending the MOSFET gate length scaling limit. Finally, high-speed NCFET RF operations are projected and designed based on experimental characterization results and Monte-Carlo transport simulations. Silicon-channel NCFETs are expected to achieve cutoff frequency over 400GHz with standard SOI device structures and over 650GHz with air-gap spacers./nThe carrier dynamics of memory program and readout operations for an n-type SOI FeFET are studied through TCAD simulations. Gate-induced drain leakages during the program operation with large negative gate biases can result in excessive hole concentrations with lifetime exceeding microseconds during the hold phase. While the excess holes result in approximately 100ps delay in the readout phase before a large read margin can be detected, it benefits the program speed and the quasi-steady-state read margin. Therefore, such effects can be utilized for low-power memory applications through proper SOI FeFET designs with the awareness of excess carrier dynamics.

Advisor: Salahuddin, Sayeef
One-Shot Interactions with Intelligent Assistants in Unfamiliar Smart Spaces

Smart space technologies have entered the mainstream home market. Most users currently interact with smart homes that they (or an acquaintance) have set up and know well. However, as these technologies spread to commercial or public environments, users will need to frequently interact with unfamiliar smart spaces. In such settings, users will be unaware of the available capabilities and the system maintainer will not be present to help. Users will need to quickly and independently 1) discover what is and is not possible, and 2) make use of available functionality. However, current smart spaces use a ``proper device name'' paradigm that requires users to know which individual devices are smart and what their proper names are in order to interact with the space. This approach makes it nearly impossible for users to operate unfamiliar smart spaces, especially when using natural language intelligent assistants. Widespread adoption of smart space systems, and all the benefits they may confer, will not be possible until this discoverability issue is solved./nIn this work, we characterize the problems associated with the proper device name paradigm and evaluate potential solutions. First, we look at the limiting effect that device-centrism has on a user's conception of system capabilities, and find that framing interactions around intelligent assistants can mediate these negative effects. Then, we examine how the use of proper names to refer to system resources poses particular challenges in smart spaces. To address these issues while preserving an assistant framing, we borrow patterns from human-to-human messaging and apply them to human-to-assistant communication. Our method of using contextual photo messages enhanced by two technologies -- augmented reality and autocomplete -- allows users to determine available functionality and achieve their goals in one attempt with a smart space they have never seen before, something no existing interface supports. The ability to easily operate unfamiliar smart spaces improves the usability of existing systems and removes a significant obstacle to the vision of ubiquitous computing.

Advisor: Dutta, Prabal
Newman, Mark W