2,474 Works

Soil stress field around driven piles

Marie-Agnes Allard
The description, equipment, and results of a series of pile-driving experiments conducted in a centrifuge using a model pile driven in dry sand are presented. The work was conceived on the basis of the modelling of a soil-structure system under an artificially generated gravitational field, and motivated by the need for experimental data for a better understanding of the complex phenomena involved in the pile-soil interaction during driving. The behavior of the pile itself has...

Soil Stress Field Around Driven Piles

Marie-Agnes Allard
The description, equipment, and results of a series of pile-driving experiments conducted in a centrifuge using a model pile driven in dry sand are presented. The work was conceived on the basis of the modelling of a soil-structure system under an artificially generated gravitational field, and motivated by the need for experimental data for a better understanding of the complex phenomena involved in the pile-soil interaction during driving. The behavior of the pile itself has...

Death or Taxes? The Political Economy of Sanitation Expenditure in Nineteenth Century Britain

Jonathan Neil Chapman
This thesis consists of three papers studying the relationship between democratic reform, expenditure on sanitation public goods and mortality in Britain in the second half of the nineteenth century. During this period decisions over spending on critical public goods such as water supply and sewer systems were made by locally elected town councils, leading to extensive variation in the level of spending across the country. This dissertation uses new historical data to examine the political...

State-Dependent Modulation of Neuronal Circuits in C. elegans Sleep

Julie YoungHee Cho
C. elegans is a compact system of 302 neurons with identifiable and mapped connections that makes it ideal for systems analysis. This work is a demonstration of what I have been able to learn about the nature of state-specific modulation and reversibility during a state called lethargus, a sleep-like state in the worm. I begin with description about the nervous system of the worm, the nature of sleep in the worm, the questions about behavior...

Chelation-enforced metal-arene interactions : insights into substrate binding and catalysis by late transition metal complexes

Sibo Lin
Understanding and catalyzing chemical reactions requiring multiple electron transfers is an endeavor relevant to many outstanding challenges in the field of chemistry. To study multi-electron reactions, a terphenyl diphosphine framework was designed to support one or more metals in multiple redox states via stabilizing interactions with the central arene of the terphenyl backbone. A variety of unusual compounds and reactions and their relevance toward prominent research efforts in chemistry are the subject of this dissertation....

Rate and Microstructure Effects on the Dynamics of Carbon Nanotube Foams

Ramathasan Thevamaran
Soft hierarchical materials often present unique functional properties that are sensitive to the geometry and organization of their micro- and nano-structural features across different lengthscales. Carbon Nanotube (CNT) foams are hierarchical materials with fibrous morphology that are known for their remarkable physical, chemical and electrical properties. Their complex microstructure has led them to exhibit intriguing mechanical responses at different length-scales and in different loading regimes. Even though these materials have been studied for mechanical behavior...

Sulfur-Cycling in Methane-Rich Ecosystems: Uncovering Microbial Processes and Novel Niches

Abigail Green Saxena
Microbial sulfur cycling communities were investigated in two methane-rich ecosystems, terrestrial mud volcanoes (TMVs) and marine methane seeps, in order to investigate niches and processes that would likely be central to the functioning of these crucial ecosystems. Terrestrial mud volcanoes represent geochemically diverse habitats with varying sulfur sources and yet sulfur-cycling in these environments remains largely unexplored. Here we characterized the sulfur-metabolizing microorganisms and activity in 4 TMVs in Azerbaijan, supporting the presence of active...

Biophysics of V(D)J recombination and Genome Packaging: In singulo studies on RAG, HMGB1, and TFAM

Geoffrey A. Lovely
The recombination-activating gene products, RAG1 and RAG2, initiate V(D)J recombination during lymphocyte development by cleaving DNA adjacent to conserved recombination signal sequences (RSSs). The reaction involves DNA binding, synapsis, and cleavage at two RSSs located on the same DNA molecule and results in the assembly of antigen receptor genes. Since their discovery full-length, RAG1 and RAG2 have been difficult to purify, and core derivatives are shown to be most active when purified from adherent 293-T...

Acceleration Sensing, Feedback Cooling, and Nonlinear Dynamics with Nanoscale Cavity-Optomechanical Devices

Alexander Grey Krause
Light has long been used for the precise measurement of moving bodies, but the burgeoning field of optomechanics is concerned with the interaction of light and matter in a regime where the typically weak radiation pressure force of light is able to push back on the moving object. This field began with the realization in the late 1960's that the momentum imparted by a recoiling photon on a mirror would place fundamental limits on the...

Visual Behavior and Preference Decision-Making in Response to Faces in High-Functioning Autism

Alma Mariam Gharib
How do we come to the decision that we like a face? This thesis investigates this important aspect of social processing and communication by examining preference decisions for faces and the role that visual behavior plays in the process. I present a series of studies designed to investigate face preference formation and gaze patterns using eye-tracking and self-reported preference ratings. I tested healthy control subjects and two clinical populations known to have deficits in social...

Stability of Hypervelocity Boundary Layers

Neal Phillip Bitter
The early stage of laminar-turbulent transition in a hypervelocity boundary layer is studied using a combination of modal linear stability analysis, transient growth analysis, and direct numerical simulation. Modal stability analysis is used to clarify the behavior of first and second mode instabilities on flat plates and sharp cones for a wide range of high enthalpy flow conditions relevant to experiments in impulse facilities. Vibrational nonequilibrium is included in this analysis, its influence on the...

Development of Nickel-Catalyzed Asymmetric Reductive Cross-Coupling of Benzylic Electrophiles

Alan Hayden Cherney
Over the last forty years, the advent of transition metal-catalyzed cross-coupling has revolutionized the synthetic chemist’s ability to generate C–C bonds. Since the 1970s, a parallel effort to control the stereochemical outcome of such transformations has yielded a variety of chiral catalyst complexes that deliver enantioenriched cross-coupled products. Nonetheless, challenges in the use of C(sp3)-hybridized coupling partners have limited asymmetric variants to a narrow fraction of the total number of cross-coupling methodologies published each year....

I. Nickel-Exchanged Zincosilicate Catalysts for the Oligomerization of Propylene and II. Organic SDA-Free Catalysts for the Methanol-to-Olefins Reaction

Mark Austin Deimund
Nickel-containing catalysts are developed to oligomerize light olefins. Two nickel-containing zincosilicates (Ni-CIT-6 and Ni-Zn-MCM-41) and two nickel-containing aluminosilicates (Ni-HiAl-BEA and Ni-USY) are synthesized as catalysts to oligomerize propylene into C3n (C6 and C9) products. All catalysts oligomerize propylene, with the zincosilicates demonstrating higher average selectivities to C3n products, likely due to the reduced acidity of the Zn heteroatom. To test whether light alkanes can be incorporated into this oligomerization reaction, a supported homogeneous catalyst is...

How Behavioral Economics Can Shape Firm Strategy and Public Policy: Lessons from the Field and Laboratory

Matthew C. Chao
Incentives are not always economic or monetary in nature. Individuals are often influenced by socially-based incentives centered on how he or she wants to be perceived in a social setting, such as the desire to publicly adhere to a norm of fairness. Likewise, individuals can also be influenced by cognitively-based incentives centered on self-perception and self-attribution, such as the desire to convince oneself that he or she is altruistic. Behavioral economists have incorporated some of...

Essays in Social and Economic Networks

Khai Xiang Chiong
This thesis consists of three chapters, and they concern the formation of social and economic networks. In particular, this thesis investigates the solution concepts of Nash equilibrium and pairwise stability in models of strategic network formation. While the first chapter studies the robustness property of Nash equilibrium in network formation games, the second and third chapters investigate the testable implication of pairwise stability in networks. The first chapter of my thesis is titled "The Robustness...

Structural and Biophysical Characterization of Variants of the Mechanosensitive Channel of Large Conductance (MsCL)

Chinenye Abiodun Idigo
The ability to sense mechanical force is vital to all organisms to interact with and respond to stimuli in their environment. Mechanosensation is critical to many physiological functions such as the senses of hearing and touch in animals, gravitropism in plants and osmoregulation in bacteria. Of these processes, the best understood at the molecular level involve bacterial mechanosensitive channels. Under hypo-osmotic stress, bacteria are able to alleviate turgor pressure through mechanosensitive channels that gate directly...

Topological Strings, Double Affine Hecke Algebras, and Exceptional Knot Homology

Ross Filip Elliot
In this thesis, we consider two main subjects: refined, composite invariants and exceptional knot homologies of torus knots. The main technical tools are double affine Hecke algebras ("DAHA") and various insights from topological string theory. In particular, we define and study the composite DAHA-superpolynomials of torus knots, which depend on pairs of Young diagrams and generalize the composite HOMFLY-PT polynomials from the full HOMFLY-PT skein of the annulus. We also describe a rich structure of...

Progress Toward the Enantioselective Total Synthesis of Ineleganolide and the Polycyclic Norcembranoid Diterpenes and Construction of the Ineleganoloids

Robert Allen, II Craig
Ineleganolide, horiolide, kavaranolide, sinulochmodin C, scabrolide A, scabrolide B, and yonarolide are related polycyclic furanobutenolide norcembranoid natural products that exhibit potent biological activity, and feature highly oxygenate carbocyclic scaffolds with complex stereochemical frameworks. Herein, we describe a unified synthetic approach toward ineleganolide and the related furanobutenolide norcembranoids. Assembly of the tetracyclic scaffold of ineleganolide is accomplished in a convergent manner from (R)-carvone and an enantioenriched cis-1,3-cyclopentenediol fragment, which is constructed by a key enantioselective allylic...

Dendrites Inhibition in Rechargeable Lithium Metal Batteries

Asghar Aryanfar
The specific high energy and power capacities of rechargeable lithium metal (Li0) batteries are ideally suited to portable devices and are valuable as storage units for intermittent renewable energy sources. Lithium, the lightest and most electropositive metal, would be the optimal anode material for rechargeable batteries if it were not for the fact that such devices fail unexpectedly by short-circuiting via the dendrites that grow across electrodes upon recharging. This phenomenon poses a major safety...

Experimental Investigation of Thrust Fault Rupture Mechanics

Vahe Gabuchian
Thrust fault earthquakes are investigated in the laboratory by generating dynamic shear ruptures along pre-existing frictional faults in rectangular plates. A considerable body of evidence suggests that dip-slip earthquakes exhibit enhanced ground motions in the acute hanging wall wedge as an outcome of broken symmetry between hanging and foot wall plates with respect to the earth surface. To understand the physical behavior of thrust fault earthquakes, particularly ground motions near the earth surface, ruptures are...

The Structure of Hippocampal Activity During REM Sleep

Andreas Hoenselaar
The hippocampus is a brain structure critical for the formation of long-term episodic memories. The current predominant theory is that memories are gradually established across neocortical networks under the influence of hippocampal activity. This process of memory consolidation is conjectured to occur during sleep, which is characterized by two different modes of activation: slow-wave sleep (SWS) and rapid eye movement (REM) sleep. The functional roles of these two different sleep states remain unknown. Paradoxically, REM...

Ab-Initio and Experimental Techniques for Studying Non-Stoichiometry and Oxygen Transport in Mixed Conducting Oxides

Chirranjeevi Balaji Gopal
The ability of cerium oxide (CeO2-δ, also called ceria), to vary its oxygen stoichiometry in response to changes in temperature or oxygen activity is key to many of its applications in catalysis and electrochemical energy storage and conversion. This thesis explores ab initio and experimental approaches to study the fundamental thermodynamic and oxygen transport properties of ceria (MxCe1-xOO2-δ), but the methods are applicable to other mixed conducting oxides as well. In the first part of...

Mesoscale Optoelectronic Design of Wire-Based Photovoltaic and Photoelectrochemical Devices

Katherine Theresa Fountaine
The overarching theme of this thesis is mesoscale optical and optoelectronic design of photovoltaic and photoelectrochemical devices. In a photovoltaic device, light absorption and charge carrier transport are coupled together on the mesoscale, and in a photoelectrochemical device, light absorption, charge carrier transport, catalysis, and solution species transport are all coupled together on the mesoscale. The work discussed herein demonstrates that simulation-based mesoscale optical and optoelectronic modeling can lead to detailed understanding of the operation...

Superionic Noble Metal Chalcogenide Thermoelectrics

Tristan William Day
Measurements and modeling of Cu2Se, Ag2Se, and Cu2S show that superionic conductors have great potential as thermoelectric materials. Cu2Se and Ag2Se are predicted to reach a zT of 1.2 at room temperature if their carrier concentrations can be reduced, and Cu-vacancy doped Cu2S reaches a maximum zT of 1.7 at 1000 K. Te-doped Ag2Se achieves a zT of 1.2 at 520 K, and could reach a zT of 1.7 if its carrier concentration could be...

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