6,636 Works

Cavity Ringdown Spectroscopy, Kinetics, and Quantum Chemistry of Atmospherically Relevant Reactions

Matthew Kiran Sprague
This thesis describes laboratory experiments and electronic structure calculations on three chemical systems relevant to tropospheric ozone chemistry: peroxynitrous acid (HOONO), hydroxymethylperoxy radical formed from HO2 + HCHO (R1), and products of alkoxy isomerization (R2). R1 and R2 were studied experimentally using a gas flow cell that combined UV photolysis with cavity ringdown spectroscopy (CRDS). All chemical systems were studied using electronic structure calculations and kinetics modeling. HOONO is one of the products of the...

Hybrid Human-Machine Vision Systems: Image Annotation using Crowds, Experts and Machines

Nils Peter Egon Welinder
The amount of digital image and video data keeps increasing at an ever-faster rate. While "big data" holds the promise of leading science to new discoveries, raw image data in itself is not of much use. In order to statistically analyze the data, it must be quantified and annotated. We argue that entirely automated methods are not accurate enough to annotate data in the short term. Crowdsourcing is an alternative that provides higher accuracy, but...

Electron Neutrino Appearance in the MINOS Experiment

Mhair-Armen Hagop Orchanian
This thesis describes a search for νe appearance in the two-detector long-baseline MINOS neutrino experiment at Fermilab, based on a data set representing an exposure of 8.2 x 1020 protons on the NuMI target. The analysis detailed herein represents an increase in sensitivity to the θ13 mixing angle of approximately 25% over previous analyses, due to improvements in the event discriminant and fitting technique. Based on our observation, we constrain the value of θ13 further,...

Classification of Sub-10 nm Aerosol: Theory, Instrument Development, and Experiment

Andrew Joseph Downard
The large diffusion coefficients of sub-10 nm aerosol have posed a long-standing challenge to the aerosol community; to understand nucleation and early growth, there is a need for methods such as those presented here that transmit a strong, high resolution signal of classified charged aerosol to the detector. I introduce a framework for comparison of the Flagan Laboratory classifiers to other instruments, and I show why our instruments perform favorably relative to these alternatives. Reducing...

Atomistic Simulations of Materials: Methods for Accurate Potentials and Realistic Time-Scales

Pratyush Tiwary
This thesis deals with achieving more realistic atomistic simulations of materials, by developing accurate and robust force-fields, and algorithms for practical time scales. I develop a formalism for generating interatomic potentials for simulating atomistic phenomena occurring at energy scales ranging from lattice vibrations to crystal defects to high-energy collisions. This is done by fitting against an extensive database of ab initio results, as well as to experimental measurements for mixed oxide nuclear fuels. The applicability...

Neutron Stars and NuSTAR: A Systematic Survey of Neutron Star Masses in High Mass X-ray Binaries & Characterization of CdZnTe Detectors for NuSTAR

Varun B. Bhalerao
My thesis centers around the study of neutron stars, especially those in massive binary systems. To this end, it has two distinct components: the observational study of neutron stars in massive binaries with a goal of measuring neutron star masses and participation in NuSTAR, the first imaging hard X-ray mission, one that is extremely well suited to the study of massive binaries and compact objects in our Galaxy. The Nuclear Spectroscopic Telescope Array (NuSTAR) is...

The Structural Biology of HIV Budding and Maturation

Megan J. Dobro
The Human Immunodeficiency Virus (HIV) depends on the ability to exit infected cells, mature into an infectious state, and infect new host cells. The structural details of exiting and maturation (known as the "late stage events") remain elusive, but further understanding could lead to new therapies. HIV exits cells by hijacking a host cellular complex called ESCRT (Endosomal Sorting Complex Required for Transport), which evolved to constrict membranes in multivesicular body formation and cytokinesis. Electron...

Scheduling for Heavy-Tailed and Light-Tailed Workloads in Queueing Systems

Jayakrishnan U. Nair
In much of classical queueing theory, workloads are assumed to be light-tailed, with job sizes being described using exponential or phase type distributions. However, over the past two decades, studies have shown that several real-world workloads exhibit heavy-tailed characteristics. As a result, there has been a strong interest in studying queues with heavy-tailed workloads. So at this stage, there is a large body of literature on queues with light-tailed workloads, and a large body of...

Network Coding and Distributed Compression over Large Networks: Some Basic Principles

Mayank Bakshi
The fields of Network Coding and Distributed Compression have focused primarily on finding the capacity for families of problems defined by either a broad class of networks topologies (e.g., directed, acyclic networks) under a narrow class of demands (e.g., multicast), or a specific network topology (e.g. three-node networks) under different types of demands (e.g. Slepian-Wolf, Ahlswede-Körner). Given the difficulty of the general problem, it is not surprising that the collection of networks that have been...

Studies of Exciton Condensation and Transport in Quantum Hall Bilayers

Aaron David Kiyoshi Finck
This thesis is a report of the transport properties of bilayer two-dimensional electron systems found in GaAs/AlGaAs double quantum well semiconductor heterostructures. When a strong perpendicular magnetic field is applied so that the total Landau filling factor is equal to one and if the two layers are close enough together, a novel quantum Hall (QH) state with strong interlayer correlations can form. This QH state is often described as an excitonic condensate, in which electrons...

The Implementation of Optofluidic Microscopy on a Chip Scale and Its Potential Applications in Biology

Lap Man Lee
This thesis presents an effort to miniaturize conventional optical microscopy to a chip level using microfluidic technology. Modern compound microscopes use a set of bulk glass lenses to form magnified images from biological objects. This limits the possibility of shrinking the size of a microscope system. The invention of micro/nanofabrication technology gives hope to engineers who want to rethink the way we build optical microscopes. This advancement can fundamentally reform the way clinicians and biologists...

A Dark-Matter Search Using the Final CDMS II Dataset and a Novel Detector of Surface Radiocontamination

Zeeshan Ahmed
Substantial evidence from galaxies, galaxy clusters, and cosmological scales suggests that ~85% of the matter of our universe is invisible. The missing matter, or "dark matter" is likely composed of non-relativistic, non-baryonic particles, which have very rare interactions with baryonic matter and with one another. Among dark matter candidates, Weakly Interacting Massive Particles (WIMPs) are particularly well motivated. In the early universe, thermally produced particles with weak-scale mass and interactions would `freeze out’ at the...

MicroRNAs 155 and 125b Physiologically and Pathologically Regulate Hematopoiesis and Immunity

Aadel Ahmed Chaudhuri
MicroRNAs are a class of ~22 nucleotide RNA molecules with roles in diverse biological processes. Here I focus on two microRNAs, miR-155 and miR-125b, and reveal pathways by which their dysregulation leads to myeloproliferative disorder (MPD) and leukemia, respectively. I begin by searching for miR-155 target genes relevant to MPD. By writing an algorithm to search microarray data for predicted microRNA target genes, I identified 89 candidate target genes for miR-155 in myeloid cells. Literature...

Cavity Optomechanics with High Stress Silicon Nitride Films

Dalziel Joseph Wilson
There has been a barrage of interest in recent years to marry the fields of nanomechanics and quantum optics. Mechanical systems provide sensitive and scalable architectures for sensing applications ranging from atomic force microscopy to gravity wave interferometry. Optical resonators driven by low noise lasers provide a quiet and well-understood means to read-out and manipulate mechanical motion, by way of the radiation pressure force. Taken to an extreme, a device consisting of a high-Q nanomechanical...

Clustering Affine Subspaces: Algorithms and Hardness

Euiwoong Lee
We study a generalization of the famous k-center problem where each object is an affine subspace of dimension Δ, and give either the first or significantly improved algorithms and hardness results for many combinations of parameters. This generalization from points (Δ=0) is motivated by the analysis of incomplete data, a pervasive challenge in statistics: incomplete data objects in Rd can be modeled as affine subspaces. We give three algorithmic results for different values of k,...

DNA Mechanics and Transcriptional Regulation in the E. coli lac Operon

Stephanie Lynn Johnson
Many gene regulatory motifs in both prokaryotes and eukaryotes involve physical manipulations of the genetic material, often on length scales short enough that the mechanical properties of the DNA significantly impact gene expression. One class of such manipulations, called “action at a distance”, includes transcription factor-mediated DNA looping, in which a binding site some distance away on the DNA is brought into close proximity with the transcription machinery at the promoter. DNA looping is a...

Three Paths to Particle Dark Matter

Samuel Kuhnman Lee
In this thesis, we explore examples of each of the three primary strategies for the detection of particle dark matter: indirect detection, direct detection, and collider production. We first examine the indirect detection of weakly interacting massive particle (WIMP) dark matter via the gamma-ray photons produced by astrophysical WIMP annihilation. Such photons may be observed by the Fermi Gamma-ray Space Telescope. We propose the gamma-ray-flux probability distribution function (PDF) as a probe of the Galactic...

Computational Biases in Decision-Making

Vanessa Janowski
Neuroeconomics has produced a number of insights into economics, psychology, and neuroscience in its relatively short existence. Here, I show how neuroeconomics can inform these fields through three studies in social decision making and decision making under risk. Specifically, I focus on computational biases inherent in our daily decisions. First, using functional magnetic resonance imaging (fMRI), I examine how we make decisions for others compared to ourselves. I find that overlapping areas of the ventromedial...

A Search for Low-Mass Dark Matter with the Cryogenic Dark Matter Search and the Development of Highly Multiplexed Phonon-Mediated Particle Detectors

David Craig Moore
A wide variety of astrophysical observations indicate that approximately 85% of the matter in the universe is nonbaryonic and nonluminous. Understanding the nature of this "dark matter" is one of the most important outstanding questions in cosmology. Weakly Interacting Massive Particles (WIMPs) are a leading candidate for dark matter since they would be thermally produced in the early universe in the correct abundance to account for the observed relic density of dark matter. If WIMPs...

MEMS for Glaucoma

Jeffrey Chun-Hui Lin
Glaucoma is an eye disease that gradually steals vision. Open angle glaucoma is one of the most common glaucoma forms, in which eye fluid (aqueous humor) produced by the ciliary body cannot be drained away normally by patients’ eyes. The accumulated eye fluid inside the anterior chamber causes high intraocular pressure (IOP), which is transmitted onto the retina in the back of the eyeball (globe), continuously suppressing and damaging the patient’s optic nerves; this may...

Engineering of Dengue Virus Refractoriness in Aedes aegypti and Development of an Underdominant Gene Drive System in Drosophila melanogaster

Kelly Jean Matzen
Vector-borne diseases have a profound impact on world health. The two most well-known and costly diseases are dengue fever and malaria, both spread by mosquito vectors. In the last decade, many new solutions to halting the spread of these diseases have been sought, including vector-mediated disease suppression. The work presented here seeks to generate alleles to effect this suppression, and engineer a drive system to replace the native population. Additional work on systems to keep...

Orbits and Interiors of Planets

Konstantin Batygin
The focus of this thesis is a collection of problems of timely interest in orbital dynamics and interior structure of planetary bodies. The first three chapters are dedicated to understanding the interior structure of close-in, gaseous extrasolar planets (hot Jupiters). In order to resolve a long-standing problem of anomalously large hot Jupiter radii, we proposed a novel magnetohydrodynamic mechanism responsible for inflation. The mechanism relies on the electro-magnetic interactions between fast atmospheric flows and the...

Cosmological Consequences of Gravitation: Structure Formation and Gravitational Waves

Laura Grace Book
This thesis contains work on four topics which fit into two broad areas of research: the quest to understand structure formation and through it the properties of the dark matter, and the search for primordial gravitational radiation. The first project details the effect of an accretion shock on the colors of satellites in galaxy clusters. A new model of ram pressure stripping including an accretion shock with variable radius is developed and implemented in the...

DNA-mediated Charge Transport in a Biological Context: Cooperation among Metalloproteins to Find Lesions in the Genome

Pamela Alisa Sontz
Damaged bases in DNA are known to lead to errors in replication and transcription, compromising the integrity of the genome. A molecular wire, DNA conducts charge with shallow distance dependence, yet mismatches and lesions attenuate this process. We have proposed a model where repair proteins, containing redox-active [4Fe4S] clusters, utilize DNA charge transport (CT) to scan the genome for lesions. Based on this model, proteins are predicted to redistribute onto strands where DNA CT is...

Synthesis and Functionalization of Second Harmonic Generation Nanocrystals and Their Application in Biological Imaging

Jelena Culic-Viskota
The discovery and use of fluorescent proteins has been of extreme importance in biological imaging of cells, tissues, and organs. In order to address some of the limitations of fluorescent tags, second harmonic generation can be used. Second harmonic generating nanoprobes allow nontoxic, long-term imaging that, with proper functionalization, can be utilized for biological imaging applications. As a proof of principle, commercial tetragonal barium titanate nanoparticles were functionalized to expose surface amine groups, which could...

Registration Year

  • 2019

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  • California Institute of Technology
  • Jet Propulsion Lab
  • Scripps College
  • University of California, Berkeley
  • The Aerospace Corporation
  • University of Massachusetts Amherst
  • University of Pennsylvania
  • University of Washington
  • University of Erlangen-Nuremberg
  • Princeton University