6,523 Works

Global Observations of Martian Clouds with the Mars Orbiter Camera of the Mars Global Surveyor Spacecraft

Huiqun Helen Wang
We have studied the global cloud distribution on Mars using red and blue global map swaths taken by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC). In Chapters 1 and 4, we summarize the results for the first and second MGS mapping years, respectively. In Chapter 2, we investigate the mechanism for a new type of "flushing" dust storm first observed by MGS. These dust storms moved from the northern high latitudes southward across...

Active Patch Array Design and Indoor Channel Modeling for Future Wireless Communications

Dai Lu
Indoor wireless LAN systems currently operate at ranges of up to 30 meters, with practical data rates of 10 Mbps. In order to achieve higher data rates, higher frequencies are under consideration. Smaller antennas are required at these frequencies, but path loss increases. To combat the large path loss and multipath, 24 GHz phased arrays are being considered. The advantage of a phased array is that it can form narrow beams to favored directions, and...

Asymptotically Optimal Multistage Hypothesis Tests

Jay L. Bartroff
This thesis investigates variable stage size multistage hypothesis testing in three different contexts, each building on the previous. We first consider the problem of sampling a random process in stages until it crosses a predetermined boundary at the end of a stage -- first for Brownian motion and later for a sum of i.i.d. random variables. A multistage sampling procedure is derived and its properties are shown to be not only sufficient but also necessary...

Optimized Network Data Storage and Topology Control

Anxiao (Andrew) Jiang
This thesis addresses two key challenges for network data-storage systems: optimizing data placement for highly efficient and robust data access, and constructing network topologies that facilitate data transmission scalable to both network sizes and network dynamics. It focuses on two new topics — data placement using erasure-correcting codes, and topology control for nodes in normed spaces. The first topic generalizes traditional file-assignment problems, and has the distinct feature of interleavingly placing data in networks. The...

The Diversity of Neutron Stars: Nearby Thermally Emitting Neutron Stars and the Compact Central Objects in Supernova Remnants

David Lior Ariel Kaplan
Neutron stars are invaluable tools for exploring stellar death, the physics of ultra-dense matter, and the effects of extremely strong magnetic fields. The observed population of neutron stars is dominated by the > 1000 radio pulsars, but there are distinct sub-populations that, while fewer in number, can have significant impact on our understanding of the issues mentioned above. These populations are the nearby, isolated neutron stars discovered by ROSAT, and the central compact objects in...

A Precision Measurement of the Weak Mixing Angle in Møller Scattering at Low Q₂

Gary Mark Jones
The electroweak theory has been probed to a high level of precision at the mass scale of the Zo through the joint contributions of LEP at CERN and the SLC at SLAC. The E158 experiment at SLAC complements these results by measuring the weak mixing angle at a Q2 of 0.026 (GeV/c)2, far below the weak scale. The experiment utilizes a 48 GeV longitudinally polarized electron beam on unpolarized atomic electrons in a target of...

A Galaxy Cluster Survey Using the Sunyaev Zel’dovich Effect

Samantha Faye Edgington
This thesis describes the design and observations with the Bolocam instrument. Bolocam is a 144-element bolometer array designed to detect the Sunyaev Zel'dovich effect, used at the Caltech Submillimeter Observatory. Bolocam can be configured to observe at 1.1, 1.4, and 2.1 mm. We conducted a galaxy cluster survey at 2.1 mm, where clusters are detected as decrements against the Cosmic Microwave Background. The survey consisted of two blank fields, for a total of one square...

Discrete Differential Operators for Computer Graphics

Mark Meyer
This thesis presents a family of discrete differential operators. Since these operators are derived taking into account the continuous notions of differential geometry, they possess many similar properties. This family consists of first- and second-order properties, both geometric and parametric. These operators are then analyzed and their practical use is tested in several example applications. First, the operators are used in a smoothing application. Due to the properties of the operators, the resulting smoothing algorithm...

Router Congestion Control

Xiaojie Gao
Congestion is a natural phenomenon in any network queuing system, and is unavoidable if the queuing system is operated at capacity. In this thesis, we study how to set the rules of a queuing system so that all the users have a self interest in controlling congestion when it happens. Queueing system is a crucial component in effective router congestion control since it determines the way packets from different sources interact with each other. If...

Development of New Asymmetric Organocatalytic Methods and Progress Towards the Total Synthesis of Guanacastepene A

Wendy Sandra Jen
The development of a new iminium-activation approach towards asymmetric organic catalysis is described. This strategy has been successfully applied to a 1,3-dipolar cycloaddition reaction to produce the first enantioselective catalytic [3+2]cycloaddition between nitrones and a,b-unsaturated aldehydes. This methodology highlights the ability of this new organocatalytic strategy to access chemical transformations not attainable though traditional Lewis acid catalysis. We have also applied this iminium-activation strategy towards the successful development of an enantioselective organocatalytic intramolecular Diels-Alder (IMDA)...

Constrained Sequential Lamination: Nonconvex Optimization and Material Microstructure

Matthew Justin Fago
A practical algorithm has been developed to construct, through sequential lamination, the partial relaxation of multiwell energy densities such as those characteristic of shape memory alloys. The resulting microstructures are in static and configurational equilibrium, and admit arbitrary deformations. The laminate topology evolves during deformation through branching and pruning operations, while a continuity constraint provides a simple model of metastability and hysteresis. In cases with strict separation of length scales, the method may be integrated...

Conformal Laminations

Vineet Gupta
A lamination on a circle is an equivalence relation on the points of the circle. Laminations can be induced on a circle by a map that is continuous on the closed disc and injective in the interior. Such laminations are characterized topologically, as being flat and closed. In this paper we investigate the conditions under which a closed, flat lamination is induced by a conformal mapping. We show that if the set of multiple points...

Radiative Transfer in Accreting Environments

Avery Earl Broderick
Accretion onto compact objects plays a central role in high-energy astrophysics. The process of accretion can substantially affect the magnetic field strength and geometry (e.g, via the magneto-rotational instability or dynamo processes) and the accreting plasma density. The presence of the compact object itself can significantly affect the character and structure of the accreting plasma as well as its emission. This is especially true, in the case of an accreting black hole, when a significant...

Visual, Attention and Object Categorization: From Psychophysics to Computational Models

Robert Jacob Peters
This thesis is arranged in two main parts. Each part relies an approach using the methods of psychophysics and computational modeling to bring abstract or high-level theories of vision closer to a concrete neurobiological foundation. The first part addresses the topic of visual object categorization. Previous studies using high-level models categorization have left unresolved issues of neurobiological relevance, including how features are extracted from the image and the role played by memory capacity in categorization...

Cell Polarity and Morphogenesis: Functions and Mechanisms of Cell Divisions in Vertebrate Gastrulation

Ying Gong
Gastrulation shapes a vertebrate embryo from an egg-shaped aggregate of cells. In many vertebrates, massive cell divisions occur during gastrulation. In this thesis, I investigate the pattern, function, and regulation of mitotic divisions in zebrafish gastrulation. Using in vivo confocal imaging and quantitative analysis, I find that cells in dorsal axial tissues preferentially divide along the direction of tissue elongation, i.e., the anterior-posterior axis of the embryo. Establishment of the spindle polarity requires Silberblick/Wnt11, Dishevelled...

Frequency Generation Techniques for Integrated Applications

Roberto Aparicio Joo
This thesis presents novel oscillator topologies and passive structures that demonstrate improvements in performance compared to existing devices in CMOS. The contributions of this work include the development of original topologies and concepts together with practical implications in the area of integrated frequency generation. A noise-shifting differential Colpitts oscillator topology is proposed. It is less sensitive to noise generated by the active devices than commonly used integrated oscillator topologies such as NMOS- or PMOS-only, and...

I. Variability of the Outgoing Thermal IR Spectra and Its Application in GCM Validation. II. The Detection of Cloud/Aerosol in the Outgoing Thermal IR Spectra

Xianglei Huang
The theme of this thesis is studying the outgoing thermal IR spectra of Earth and Mars. It is divided into two parts: the first part (Chapters 1-4) is focused on the variability seen in the outgoing thermal IR spectra and its application in validating model simulation, and the second part (Chapters 5-6) concentrates on the detection of cirrus (cirrus/dust aerosol) from terrestrial (Martian) outgoing thermal IR spectra. In Chapter 1, an example of climate change...

RG-Flows, AdS/CFT Correspondence and Stability of Non-Dilatonic Branes

Arkadas Inan Ozakin
The possibility of having multiple renormalization group (RG) flows (one of which is supersymmetric) between two fixed points is investigated in the context of anti de Sitter / conformal field theory (AdS/CFT) correspondence. An analysis of a toy-model potential suggests that such flows are likely to exist. Superpotential methods are used in the context of finite temperature AdS/CFT to derive a black brane solution which approximates various finite temperature RG-flows in AdS/CFT near the horizon....

Four-Dimensional Galois Representations of Solvable Type and Automorphic Forms

Kimball Lee Martin
We investigate the Artin and strong Artin conjectures for continuous, four-dimensional complex Galois representations of solvable type.

Microfluidic Technologies for Structural Biology

Carl Lars Genghis Hansen
In the post-genomic era, X-ray crystallography has emerged as the workhorse of large-scale structural biology initiatives that seek to understand protein function and interaction at the atomic scale. Despite impressive technological advances in X-ray sources, phasing techniques, and computing power, the determination of protein structure has been severely hampered by the difficulties in obtaining high-quality protein crystals. Emergent technologies utilizing microfluidics now have the potential to solve these problems on several levels, both by allowing...

The Conjecture of Birch and Swinnerton-Dyer for Elliptic Curves with Complex Multiplication by a Nonmaximal Order

Jason Andrew Colwell
The Conjecture of Birch and Swinnerton-Dyer relates an analytic invariant of an elliptic curve -- the value of the L-function, to an algebraic invariant of the curve -- the order of the Tate--Shafarevich group. Gross has refined the Birch--Swinnerton-Dyer Conjecture in the case of an elliptic curve with complex multiplication by the full ring of integers in a quadratic imaginary field. It is this version which interests us here. Gross' Conjecture has been reformulated, by...

Eigenvalue Inequalities in Quantum Information Processing

Sumit Kumar Daftuar
This thesis develops restrictions governing how a quantum system, jointly held by two parties, can be altered by the local actions of those parties, under assumptions about how they may communicate. These restrictions are expressed as constraints involving the eigenvalues of the density matrix of one of the parties. The thesis is divided into two parts. Part I (Chapters 1-4) explores what is possible if the two parties may use only classical communication. A well-known...

Oxidative DNA Damage by Long-Range Charge Transport

Sarah Delaney
Ever since the elucidation of the double helical structure of DNA, it has been proposed that the stack of base pairs within the double helix may mediate charge transport (CT) reactions. In fact, CT through DNA can result in chemistry at a distance, yielding oxidative DNA damage at a site remote from the bound oxidant. DNA CT chemistry depends upon coupling within the stacked base pair array, and this chemistry is remarkably sensitive to sequence-dependent...

Optimization Algorithms for Realizable Signal-Adapted Filter Banks

Andre Tkacenko
Multirate filter banks are fundamental systems commonly used in digital signal processing (DSP). Typically, they are used to decompose a discrete-time signal into a set of frequency selective components called subband signals. Filter banks have been found to be useful for lossy data compression schemes such as MP3 and JPEG 2000, denoising, and signal estimation. In the last decade, transmultiplexers, the dual structures of multirate filter banks, have been shown to be useful in digital...

Studies and Applications of Hyperpolarized ¹²⁹-Xe

Wenjin Shao
In this thesis, research work concerning studies and applications of hyperpolarized 129-Xe is presented. The research includes two projects. The first project is the measurement and interpretation of the spin-exchange rates between ¹²⁹-Xe and three alkali metals Rb, Cs, and K, for the cell density range of 0.2-0.7 amagats, with the alkali number densities directly measured by the Faraday rotation method. The determination of the constants governing the spin-exchange process provides a better understanding of...

Registration Year

  • 2019
    6,523

Resource Types

  • Text
    6,523

Affiliations

  • California Institute of Technology
    6,523