10,784 Works

On Ultrafast Time-Domain TeraHertz Spectroscopy in the Condensed Phase: Linear Spectroscopic Measurements of Hydrogen-Bond Dynamics of Astrochemical Ice Analogs and Nonlinear TeraHertz Kerr Effect Measurements of Vibrational Quantum Beats

Marco Alberto Allodi
Much of the chemistry that affects life on planet Earth occurs in the condensed phase. The TeraHertz (THz) or far-infrared (far-IR) region of the electromagnetic spectrum (from 0.1 THz to 10 THz, 3 cm-1 to 300 cm-1, or 3000 μm to 30 μm) has been shown to provide unique possibilities in the study of condensed-phase processes. The goal of this work is to expand the possibilities available in the THz region and undertake new investigations...

Chemical and Electrochemical Behavior of Graphene-Covered Silicon Photoanodes

Adam Christopher Nielander
This dissertation describes efforts over the last five years to develop protective layers for semiconductor photoelectrodes based on monolayer or few-layer graphene sheets. Graphene is an attractive candidate for a protective layer because of its known chemical inertness, transparency, ease of deposition, and limited number of electronic states. Monolayer graphene was found to effectively inhibit loss of photocurrent over 1000 seconds at n-Si/aqueous electrolyte interfaces that exhibit total loss over photocurrent over 100 seconds. Further,...

Nanophotonic Light Trapping In Thin Solar Cells

Dennis Michael Callahan
Over the last several decades there have been significant advances in the study and understanding of light behavior in nanoscale geometries. Entire fields such as those based on photonic crystals, plasmonics and metamaterials have been developed, accelerating the growth of knowledge related to nanoscale light manipulation. Coupled with recent interest in cheap, reliable renewable energy, a new field has blossomed, that of nanophotonic solar cells. In this thesis, we examine important properties of thin-film solar...

Battery-Powered RF Pre-Ionization System for the Caltech Magnetohydrodynamically-Driven Jet Experiment: RF Discharge Properties and MHD-Driven Jet Dynamics

Vernon Hampden Chaplin
This thesis describes investigations of two classes of laboratory plasmas with rather different properties: partially ionized low pressure radiofrequency (RF) discharges, and fully ionized high density magnetohydrodynamically (MHD)-driven jets. An RF pre-ionization system was developed to enable neutral gas breakdown at lower pressures and create hotter, faster jets in the Caltech MHD-Driven Jet Experiment. The RF plasma source used a custom pulsed 3 kW 13.56 MHz RF power amplifier that was powered by AA batteries,...

Binding Studies of Neuronal Nicotinic Acetylcholine Receptors Expressing Unnatural Amino Acids

Ximena Da Silva Tavares
Nicotinic acetylcholine receptors are pentameric ligand-gated ion channels mediating fast synaptic transmission throughout the peripheral and central nervous systems. They have been implicated in various processes related to cognitive functions, learning and memory, arousal, reward, motor control and analgesia. Therefore, these receptors present alluring potential therapeutic targets for the treatment of pain, epilepsy, Alzheimer’s disease, Parkinson’s disease, Tourette’s syndrome, schizophrenia, anxiety, depression and nicotine addiction. The work detailed in this thesis focuses on binding studies...

The Regulation of Sleep and Circadian Rhythms: The Role of Melatonin and Adenosine in Zebrafish

Avni Vasant Gandhi
Sleep is a highly conserved behavioral state whose regulation is still unclear. In this thesis I initially briefly introduce the known sleep circuitry and regulation in vertebrates, and why zebrafish is seen as a good model to study sleep-regulation. I describe the existing two-process model of sleep regulation, which posits that the two processes C (circadian) and S (homeostatic) control timing of sleep-wake behavior. I then study the role melatonin plays in the circadian regulation...

Observations and Modeling of Tropical Planetary Atmospheres

Anne Louise Laraia
This thesis is a comprised of three different projects within the topic of tropical atmospheric dynamics. First, I analyze observations of thermal radiation from Saturn’s atmosphere and from them, determine the latitudinal distribution of ammonia vapor near the 1.5-bar pressure level. The most prominent feature of the observations is the high brightness temperature of Saturn’s subtropical latitudes on either side of the equator. After comparing the observations to a microwave radiative transfer model, I find...

Injection Locked Clocking and Transmitter Equalization Techniques for Chip to Chip Interconnects

Mayank Raj
Semiconductor technology scaling has enabled drastic growth in the computational capacity of integrated circuits (ICs). This constant growth drives an increasing demand for high bandwidth communication between ICs. Electrical channel bandwidth has not been able to keep up with this demand, making I/O link design more challenging. Interconnects which employ optical channels have negligible frequency dependent loss and provide a potential solution to this I/O bandwidth problem. Apart from the type of channel, efficient high-speed...

Strategies for the Stereoselective Synthesis of Carbon Quaternary Centers via Transition Metal-Catalyzed Alkylation of Enolate Compounds

Corey Michael Reeves
Notwithstanding advances in modern chemical methods, the selective installation of sterically encumbered carbon stereocenters, in particular all-carbon quaternary centers, remains an unsolved problem in organic chemistry. The prevalence of all-carbon quaternary centers in biologically active natural products and pharmaceutical compounds provides a strong impetus to address current limitations in the state of the art of their generation. This thesis presents four related projects, all of which share in the goal of constructing highly-congested carbon centers...

Two and Three Finger Caging of Polygons and Polyhedra

Thomas F. Allen
Multi-finger caging offers a rigorous and robust approach to robot grasping. This thesis provides several novel algorithms for caging polygons and polyhedra in two and three dimensions. Caging refers to a robotic grasp that does not necessarily immobilize an object, but prevents it from escaping to infinity. The first algorithm considers caging a polygon in two dimensions using two point fingers. The second algorithm extends the first to three dimensions. The third algorithm considers caging...

Heteroepitaxy of Group IV and Group III-V semiconductor alloys for photovoltaic applications

Christopher Tien Chen
Photovoltaic energy conversion represents a economically viable technology for realizing collection of the largest energy resource known to the Earth -- the sun. Energy conversion efficiency is the most leveraging factor in the price of energy derived from this process. This thesis focuses on two routes for high efficiency, low cost devices: first, to use Group IV semiconductor alloy wire array bottom cells and epitaxially grown Group III-V compound semiconductor alloy top cells in a...

Incremental Control Synthesis for Robotics in the Presence of Temporal Logic Specifications

Scott Carlton Livingston
This thesis presents methods for incrementally constructing controllers in the presence of uncertainty and nonlinear dynamics. The basic setting is motion planning subject to temporal logic specifications. Broadly, two categories of problems are treated. The first is reactive formal synthesis when so-called discrete abstractions are available. The fragment of linear-time temporal logic (LTL) known as GR(1) is used to express assumptions about an adversarial environment and requirements of the controller. Two problems of changes to...

Earthquakes of the Nepal Himalaya : Towards a Physical Model of the Seismic Cycle

Thomas Joachim Ader
Home to hundreds of millions of souls and land of excessiveness, the Himalaya is also the locus of a unique seismicity whose scope and peculiarities still remain to this day somewhat mysterious. Having claimed the lives of kings, or turned ancient timeworn cities into heaps of rubbles and ruins, earthquakes eerily inhabit Nepalese folk tales with the fatalistic message that nothing lasts forever. From a scientific point of view as much as from a human...

Stability of Electrode-Electrolyte Interfaces During Charging in Lithium Batteries

Panagiotis Philippos Natsiavas
In this thesis we study the growth of a Li electrode-electrolyte interface in the presence of an elastic prestress. In particular, we focus our interest on Li-air batteries with a solid electrolyte, LIPON, which is a new type of secondary or rechargeable battery. Theoretical studies and experimental evidence show that during the process of charging the battery the replated lithium adds unevenly to the electrode surface. This phenomenon eventually leads to dendrite formation as the...

Photonic and Device Design Principles for Ultrahigh-Efficiency (>50%), Spectrum-Splitting Photovoltaics

Carissa Nicole Eisler
The sun has the potential to power the Earth's total energy needs, but electricity from solar power still constitutes an extremely small fraction of our power generation because of its high cost relative to traditional energy sources. Therefore, the cost of solar must be reduced to realize a more sustainable future. This can be achieved by significantly increasing the efficiency of modules that convert solar radiation to electricity. In this thesis, we consider several strategies...

DNA-Mediated Charge Transport Signaling Within the Cell

Michael Andrew Grodick
DNA possesses the curious ability to conduct charge longitudinally through the π-stacked base pairs that reside within the interior of the double helix. The rate of charge transport (CT) through DNA has a shallow distance dependence. DNA CT can occur over at least 34 nm, a very long molecular distance. Lastly, DNA CT is exquisitely sensitive to disruptions, such as DNA damage, that affect the dynamics of base-pair stacking. Many DNA repair and DNA-processing enzymes...

Robust Control of Evolutionary Dynamics

Vanessa Danielle Jonsson
The application of principles from evolutionary biology has long been used to gain new insights into the progression and clinical control of both infectious diseases and neoplasms. This iterative evolutionary process consists of expansion, diversification and selection within an adaptive landscape - species are subject to random genetic or epigenetic alterations that result in variations; genetic information is inherited through asexual reproduction and strong selective pressures such as therapeutic intervention can lead to the adaptation...

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...

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...

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...

Does Richard Feynman Dream of Electric Sheep? Topics on Quantum Field Theory, Quantum Computing, and Computer Science

Junyu Liu
In this thesis, we mainly discuss three topics in theoretical physics: a proof of the weak gravity conjecture, a basic statement in the string theory landscape using the black hole entropy, solving the critical O(3) model using the conformal bootstrap method involving semidefinite programming, and numerical simulation of the false vacuum decay using tensor network methods. Those topics cover different approaches to deep understanding of quantum field theories using concepts and methods of information theory,...

Applications of descriptive set theory to topology and analysis

Slawomir J. Solecki
In Chapter 1, we prove that for every family I of closed subsets of a Polish space each ∑^1_1 set can be covered by countably many members of I or else contains a nonempty ∏^0_2 set which cannot be covered by countably many members of I. We derive from it the general form of Hurewicz's theorem due to Kechris, Louveau, and Woodin, and a theorem of Feng on the open covering axiom. Also some well...

Exact solutions for two-dimensional Stokes flow

Darren G. Crowdy
This thesis comprises three parts. The principal topic is presented in Part I and concerns the problem of the free-boundary evolution of two dimensional, slow, viscous (Stokes) fluid driven by capillarity. A new theory of exact solutions is presented using a novel global approach involving complex line integrals around the fluid boundaries. It is demonstrated how the consideration of appropriate sets of geometrical line integral quantities leads to a concise theoretical reformulation of the problem....

Structure-, stereochemistry-, and metal-regulated DNA binding/cleaving molecules

John Hampton Griffin
In the cell, the binding of proteins to specific sequences of double helical DNA is essential for controlling the processes of protein synthesis (at the level of DNA transcription) and cell proliferation (at the level of DNA replication). In the laboratory, the sequence-specific DNA binding/cleaving properties of restriction endonuclease enzymes (secreted by microorganisms to protect them from foreign DNA molecules) have helped to fuel a revolution in molecular biology. The strength and specificity of a...

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  • California Institute of Technology
  • Guangdong Academy of Agricultural Sciences
  • Brigham Young University
  • Chinese PLA General Hospital
  • United States National Library of Medicine
  • Post Graduate Institute of Medical Education and Research
  • University of Pennsylvania
  • National Human Genome Research Institute
  • Huazhong University of Science and Technology
  • Shanghai University of Traditional Chinese Medicine