VictorJuiz/thesis huggingface dataset:
Interface Engineering of Garnet Solid Electrolytes

Solid lithium ion conductors represent a promising class of materials for next generation high energy density batteries, with the potential for enabling use of high capacity Li metal anodes and providing opportunities for novel lithium-free cathode materials. However, highly resistive interfaces stymie their practical use. This urgent scientific challenge requires mechanistic understanding of ion transport at interfaces, as well as development of novel processes to achieve low interfacial resistances./nThe goal of this PhD dissertation was to generate fundamental understandings of garnet-structured Al substituted Li7La3Zr2O12 (LLZO) electrolyte surfaces and interfaces with lithium metal electrodes. Specifically in this research, the topmost surface microstructure, local chemical environment, and surface chemistry were carefully studied. The ceramic processing of garnet is discussed and ways to control the sintering behavior and microstructures were explored and successfully demonstrated. Factors contributing to high interfacial resistance were systematically studied. The source of the high interfacial impedance has been traced to the presence of Li2CO3 on pellet surfaces resulting from air exposure after processing. In addition, it was discovered that surface grain boundaries are surprisingly fast ion transport pathways and surface microstructure is critically important to lithium ion transport at interfaces. Complex homo- and heterostructured LLZO solid electrolytes with controllable surface and bulk microstructures were successfully fabricated, which allowed the comparison and separation of the contribution from the surface and the bulk. Engineered pellet surfaces allowed us to achieve the lowest interfacial resistance ever reported for this composition, resulting in significantly improved cycling behavior. Lastly, it was found that LLZO surfaces can be effectively stabilized under air exposure conditions, preventing Li2CO3 formation and maintaining low interfacial resistances. This opens new opportunities for garnet solid electrolyte in practical applications.

Advisor: De Jonghe, Lutgard C
Doeff, Marca M
Creating, imaging, and exploiting collective excitations of a multicomponent Bose-Einstein condensate

Ultracold atomic gas systems provide a remarkably versatile platform for studying a wide range of physical phenomena, from analogue particle physics and gravity, to the emergence of subtle and profound order in many body and condensed matter systems. In addition, ultracold atomic gas systems can be used to perform a range of precision measurements, from time keeping to variations in the fine structure constant. In this dissertation, I describe our efforts to build a new apparatus capable testing a range of techniques for performing precision measurements in a magnetic storage ring for cold, possibly Bose-condensed, lithium and rubidium atoms. Next, I briefly touch upon our explorations of spin vortices in a ferromagnetic rubidium Bose-Einstein condensate before presenting an exhaustive account of our work using free-particle-like magnon excitations of the ferromagnetic gas to cool it and measure its temperature in a never-before-seen regime of low entropy. Using magnons as a thermometer, we measure temperatures as low as one nanokelvin in gases with an entropy per particle of about one thousandth of the Boltzmann constant, 0.001 k_B. I conclude by presenting the details of our procedure for calculating the entropy of our coldest, lowest entropy gases in the regime where the local density approximation does not apply.

Advisor: Stamper-Kurn, Dan M
Quasilinear dynamics of KdV-type equations

We consider the behavior of nonlinear KdV-type equations that admit quasilinear dynamics in the sense that the nonlinear flow cannot be simply treated as a perturbation of the linear flow, even for small initial data./nWe treat two problems in particular. First we study the local dynamics of KdV-type equations with nonlinearities involving two spatial derivatives. A key obstruction to well-posedness arises from to the Mizohata condition. This leads to an additional integrability requirement for the solution in the absence of a suitable null structure. In this case we prove local well-posedness for large, low-regularity data in translation-invariant spaces./nSecond we explore the global dynamics of the modified Korteweg de-Vries equation. We establish modified asymptotic behavior without relying on the integrable structure of the equation. This approach has the advantage that it can be used for a wide class of short-range perturbations of the mKdV. To give a thorough description of the asymptotic behavior we prove an asymptotic completeness result that relates mKdV solutions to the 1-parameter family of solutions to the Painlevé II equation.

Advisor: Tataru, Daniel I
Engineering Dilute Nitride Semiconductor Alloys for Intermediate Band Solar Cells

The growth and characterization of GaAs nanowires and GaNPAs thin-films is discussed within the context of finding a material system that is suitable as an intermediate band solar cell (IBSC) absorber. The IBSC is an attractive concept proposed to exceed the Shockley-Queisser detailed balance limit for photovoltaic efficiency. These solar cells have an additional intermediate band, allowing for the absorption of below bandgap photons, thus resulting in an increase in photocurrent and higher efficiency. Suitable materials systems for the implementation of the IBSC concept, however, are presently lacking. Recent work on the highly-mismatched alloy (HMA) GaAsN has shown that the unique features of the electronic band structure demonstrate optical activity of three energy bands and have led to the realization of a proof-of-concept IBSC. GaAsN, however, is not without shortcomings. Another HMA material, GaNPAs, which offers a wide range of bandgap tunability and is better matched to the solar spectrum is proposed. This work covers the optical characterization of both GaAs nanowires and GaAsPN using traditional visible-light semiconductor characterization techniques including optical absorption spectroscopy, photo-modulated reflectance, steady-state photoluminescence, and spectral photoconductivity. Additionally, photovoltaic devices based on GaNPAs are demonstrated and assessed as potential IBSCs.

Advisor: Dubon, Oscar D
Wu, Junqiao
The Mainstream Right, the Far Right, and Coalition Formation in Western Europe

As long as far-right parties – known chiefly for their vehement opposition to immigration – have competed in contemporary Western Europe, scholars and observers have been concerned about these parties’ implications for liberal democracy. Many originally believed that far- right parties would fade away due to a lack of voter support and their isolation by mainstream parties. Since 1994, however, far-right parties have been included in 17 governing coalitions across Western Europe. What explains the switch from exclusion to inclusion in Europe, and what drives mainstream-right parties’ decisions to include or exclude the far right from coalitions today?/nMy argument is centered on the cost of far-right exclusion, in terms of both office and policy goals for the mainstream right. I argue, first, that the major mainstream parties of Western Europe initially maintained the exclusion of the far right because it was relatively costless: They could govern and achieve policy goals without the far right. During this period of exclusion, however, major parties of both the left and right attempted to win back voters lost to the far right by enacting more restrictive immigration policies; they would borrow from the far right as long as it was beneficial./nSecond, I argue that the mainstream right has increasingly treated the far right as it would any other party during coalition decisions. Major mainstream parties prioritize being in government, and will select the coalition that offers both stability and the ability to achieve policy goals in areas of greatest importance to them at the time. As the far right continued to attract voters throughout the late 1980s and early 1990s, the mainstream right realized that working with the far right – which was now a more useful partner, as it had more legislative seats – might result in more advantageous policy compromises. Once far-right parties could be useful to the mainstream right, exclusion became a more costly strategy./nThird, far-right parties can be attractive coalition partners to the mainstream right be- cause they are flexible on most issues – immigration excepted – and thus more willing to give the mainstream right its preferred policies in exchange for gains in immigration. Additionally, far-right parties are nearly always smaller than the major mainstream-right parties, so the mainstream parties are able to carry more weight in coalition decisions and obtain important ministerial positions./nI demonstrate my argument through in-depth case studies of Austria and the Netherlands, from the 1980s through the present. Both countries have had far-right parties in and out of government, providing important variation on the dependent variable. Finally, I show the wider applicability of my argument in two ways by extending my arguments about inclusion and exclusion to coalition-like agreements in the United Kingdom and France, as well as to mainstream left responses to far-left parties in Europe.

Advisor: Levy, Jonah D.
Microfluidic technologies for rapid, high-throughput screening and selection of antibodies for disease diagnostics and novel therapeutics

With relevance spanning from disease diagnostics such as immunohistochemistry to immunoassays and therapeutics, antibody reagents play a critical role in the life sciences, clinical chemistry, and clinical medicine. Approaches such as immunohistochemistry (IHC), and immunoassays, all work by exploiting the principle that antibodies bind specifically to antigens of interest. IHC uses antibodies to detect antigens on cancerous tissue, and immunoassays use antibodies to identify biomarkers both for a myriad of disease diagnostics for cancer and infections diseases. Currently, antibody-based proteomic approaches such as immunohistochemistry and technologies that serve to diagnose and advance therapeutics are severely limited due to non-specific antibody binding, low specificity, and reproducibility issues. Selecting antibodies based on their antigen binding kinetic properties, such as their association and dissociation rate constants, kon and koff, can provide a quantitative metric that can further optimize and validate immunoreagent selection. These rate constants quantify the ability for an antibody to associate (bind) or dissociate (unbind) to a target analyte and determines inherent binding strength. Therefore a metric such as this has the power to eliminate problems seen by clinicians, researchers, and drug developers alike in regards to false positive, false negatives, and problems with reproducibility seen in antibody-based approaches and inform assay design. Consequently, scalable and efficient analytical tools for informed selection of reliable antibody reagents would have wide impact. In this work, I have developed a highly scalable, rapid, microfluidic screening assay, that is able to assess important but difficult to characterize interaction kinetics for antibodies and protein-protein interactions. This work includes a novel screening assay for quantitative characterization of binding kinetics for the development of new biomarker discovery, disease diagnostics, and novel therapies and advances antibody-based proteomics.

Advisor: Herr, Amy E
Optogenetic stimulation, and control or promotion of epileptiform activity, in a mean field model of the human cortex

Epilepsy is a neural network disorder that manifests when certain elements (neuron types, sub-networks) malfunction or fail. Epileptiform activity, in turn, is characterized by the excessive synchronous firing of populations of neurons. In this dissertation, we present a mathematical model of the human cortex based on the activity of populations of neurons best captured at the meso-scale to study epileptic seizure dynamics. We then investigate further developments of the use of a spatially, temporally and cell type specific stimulation technique called optogenetics to trigger or to inhibit epileptiform activity in the cortical model./nOptogenetics involves the genetic modification of a host neuron to express light activated ion channels. To incorporate this method of stimulation into the meso-scale cortical model, we first develop a scale free mathematical model of optogenetic channel dynamics, which enables study of micro-scale level optogenetic activity at the meso-scale. We then integrate the optogenetic model into the meso-scale cortical model to study the combined dynamics of cortico-optogenetic activity in time and two spatial dimensions. Through this combined model, we explore the efficacy of optogenetic stimulation in an open loop configuration to inhibit epileptic seizures. Next, we close the loop using techniques of classical control theory, and investigate the controllability of seizures in two parameter spaces that correspond well with patient seizure data. By basing our control effort on measurements of cortical activity that are clinically relevant, we aim to provide a physiologically safe and efficient way of seizure inhibition. We also study the dynamics of the combined cortico-optogenetic model using bifurcation analysis. We then explore the use of optogenetic stimulation as an excitatory technique to drive seizure like activity in a normally functioning cortical model. All of this makes a strong case for the consideration of optogenetics as a highly specific cortical stimulation modality in seizure research./nFinally, we present preliminary results from work that describes the link between cortical metabolic demands and cortical activity. A quantitative definition of this link will aid in reconciling the different temporal scales of electrode measurements and imaging techniques like functional magnetic resonance imaging, while also providing a clearer picture of the role of glucose and oxygen metabolism in multiple states of cortical activity, such as normal sleep, awake, and seizure states.

Advisor: Szeri, Andrew J
Kosalan Philosophy in the Kāṇva Śatapatha Brāhmaṇa and the Suttanipāta

This dissertation traces regional philosophy in religious texts, namely the Kāṇva Śatapatha Brāhmaṇa and the Suttanipāta. Receiving the Vedas in the East, Yājñavalkya and the Vājasaneyins enlivened earlier Vedic concepts and augmented Vedic propensities for asceticism. The region of Kosala flourished during the lifetime of Śākyamuni Buddha, and as a result, the Kāṇva School formed an important part of the cultural milieu in which the historical Buddha lived. The Suttanipāta depicts the Buddha as knowledgeable in Vedic practices and lore and as interacting with brāhmaṇas, arguably both before and after a separate Buddhist identity formed. Considering this background, the relationship between late Vedic and early Buddhist thought must be reassessed. Because value is acquired and erased when concepts circulate, the Buddha’s teaching in the Suttanipāta can be considered a philosophical project to create new concepts and to translate practices that respond to a changing milieu./nThrough a close analysis of Yājñavalkya’s interpretation of the agnihotra and Sāvitrī ṛk as related to cognitive processes, this study uncovers the metaphysical meaning of philosophical concepts, such as svàr, vā́ja, dhī́, and prajā, etc. In particular, the dissertation demonstrates that Yājñavalkya’s concept of karma (rite) in the Kāṇva Śatapatha Brāhmaṇa implies what is called karmic retribution. Vedic concepts for the unmanifest govern the idea of karmic retribution and the goal of becoming cognizant of the inflow of unmanifest energy in conscious cognition. The Buddha again revitalizes these concepts when teaching a brāhmaṇa audience in the Suttanipāta. The Buddhist concepts of upadhi, āsava, crossing over to the far shore, and the serpent shedding his skin enliven earlier Vedic philosophy, which was expressed in systems of conceptual metaphors. In this way, Kosalan philosophy in the Kāṇva Śatapatha Brāhmaṇa and the Suttanipāta advances theories of causality and two modes of knowing—one karmically conditioned by past actions (saṃjñā/saññā), and the other a direct knowing (prajñāna/paññā) unmediated by karmic retribution.

Advisor: Goldman, Robert P
Fast Predictive Control of Networked Energy Systems

In this thesis we study the optimal control of networked energy systems. Networked energy systems consist of a collection of energy storage nodes and a network of links and inputs which allow energy to be exchanged, injected, or removed from the nodes. The nodes may exchange energy between each other autonomously or via controlled flows between the nodes. Examples of networked systems include building heating, ventilation, and air conditioning (HVAC) systems and networked battery systems. In the building system example, the nodes of the system are rooms which store thermal energy in the air and other elements which have thermal capacity. The rooms transfer energy autonomously through thermal conduction, convection, and radiation. Thermal energy can be injected into or removed from the rooms via conditioned air or slabs. In the case of a networked battery system, the batteries store electrical energy in their chemical cells. The batteries may be electrically linked so that a controller can move electrical charge from one battery to another. Networked energy systems are typically large-scale (contain many states and inputs), affected by uncertain forecasts and disturbances, and require fast computation on cheap embedded platforms./nIn this thesis, the optimal control technique we study is model predictive control for networked energy systems. Model predictive or receding horizon control is a time-domain optimization-based control technique which uses predictive models of a system to forecast its behavior and minimize a performance cost subject to system constraints. In this thesis we address two primary issues concerning model predictive control for networked energy systems: robustness to uncertainty in forecasts and reducing the complexity of the large-scale optimization problem for use in embedded platforms. The first half of the thesis deals primarily with the efficient computation of robust controllers for dealing with random and adversarial uncertainties in the forecasts. We show that the exact control policies can be found efficiently for certain types of robust predictive control problems. The second half of the thesis deals with improving computation speed and memory usage through model reduction and exploitation of symmetries in the predictive control problem. We present a model reduction technique tailored for networked systems which preserves sparsity and thus greatly improves computation speed. We also show how to apply symmetry methods for efficient computation of explicit model predictive controllers to systems which are not perfectly symmetric.

Advisor: Borrelli, Francesco
Serum albumin promotes stem cell proliferation and neurogenesis in a rodent model of post-traumatic epilepsy

Traumatic brain injuries (TBIs) cause the breakdown of the blood-brain barrier (BBB) and the extravasation of serum albumin, and induce epileptiform activity via astrocytic transforming growth factor β (TGF-β) signaling. Intracerebroventricular (ICV) infusion of serum albumin alone is sufficient to induce seizures in rodents and has been associated with increased TGF-β signaling and synaptogenesis, which contribute to epileptogenesis. This study demonstrates that ICV infusion of serum albumin also promotes the proliferation of neural stem cells (NSCs) and aberrant neurogenesis in the dentate gyrus of the adult mouse. Treatment with an angiotensin II type 1 receptor antagonist (Losartan) prevents these changes. Furthermore, we demonstrate that serum albumin alone does not affect the proliferation of these NSCs in vitro, and is not sufficient to induce the secretion of astrocytic proliferative signals. This suggests that the increase in proliferation observed in animals exposed to serum albumin may require activity-induced proliferative signals from epileptiform activity, contributions from other cells in the niche in addition to astrocytes, cell-to-cell contact signals, or all three. These observations suggest a mechanism for the increase in neurogenesis observed in the post-injury epileptic brain and offer an opportunity to develop a therapeutic intervention to prevent epileptogenesis after TBIs.

Advisor: Kaufer, Daniela
Essays in Behavioral Economics

This dissertation consists of two chapters on behavioral economics./nChapter one analyzes mutual fund flows from 1999 to 2012 to provide evidence that financial advisers exploit their clients' extrapolative beliefs to sell funds that pay high commissions. Utilizing comparisons between twin retail mutual fund share classes that differ only in commissions, I find a strong positive correlation between commission levels and return chasing. Fund flows from high commission shares show increased purchases of past winners, but no increased redemptions of past losers. This pattern is consistent with the incentives from 12b-1 commissions, which pay advisers to keep clients invested in high commission funds, but is hard to reconcile with alternative explanations such as advisers reducing search costs for quality funds, or return chasers self-selecting into high commission advisers. My findings support the SEC's recent efforts at restructuring 12b-1 commissions, as well as the White House's recent push to require fiduciary duty from all retirement advisers./nChapter two attempts to isolate the effects of violent video game sales on crime using a novel data set of state-level game sales from 2006 to 2010. The panel database, constructed using NPD group publications and state-level sales weights computed from Google Trends search data, overcomes the time-series data restrictions faced by previous works. However, the state-level variation in this panel data was not enough to disentangle the impact of game sales from time trends because video game sales are highly correlated across states. I document the methodology used to reconstruct the panel data using Google Trends, as this could prove useful in other situations where panel data is difficult or expensive to obtain.

Advisor: DellaVigna, Stefano