Physics Commons^™

Biophysical Characterization Of A De Novo Elastin, Kelly Nicole Greenland

Dissertations, Theses, and Capstone Projects

Natural human elastin is found in tissue such as the lungs, arteries, and skin. This protein is formed at birth with no mechanism present to repair or supplement the initial quantity formed. As a result, the functionality and durability of elastin's elasticity is critically important. To date, the mechanics of this ability to stretch and recoil is not fully understood. This study utilizes de novo protein design to create a small library of simplistic versions of elastin-like proteins, demonstrate the elastin-like proteins, maintain elastin's functionality, and inquire into its structure using solution nuclear magnetic resonance (NMR).

Elastin is formed from …

Metasurfaces For Photon Sorting And Selective Absorption, Isroel Moshe Mandel

Dissertations, Theses, and Capstone Projects

Metamaterials are a recent discovery gaining much interest due to their promising applications to multiple devices in sensing, imaging, photovoltaics, nonlinear optics, heat conversion, sorters, and multitudes of other devices. These metamaterials are made of subunits called meta-atoms which take a role similar to that of atoms in bulk crystals. However, unlike their atom counterparts, these meta-atoms are macroscopic and can be engineered to respond to a driving field in a desired way. Metasurfaces, the 2-dimensional analog of metamaterials, have been shown to possess the ability to control light in novel ways. In this work, we investigate a particular type …

Another One Busts The Dust, Keiko Hiranaka

Dissertations, Theses, and Capstone Projects

Brown dwarfs are substellar objects with core temperatures insufficient for sustained hydrogen fusion. Their physical properties such as mass, temperature, and radius are similar to those of gas giant planets, so studying brown dwarfs may also benefit exoplanet studies.

There is a population of 'red' L dwarfs, which have redder J - K colors in the near-infrared than normal objects. Red L dwarfs include young, low-gravity objects, which are systematically red, and red field-gravity objects. The observed reddening in L dwarfs is not well explained by current atmosphere models.

We present an analysis of red L dwarfs using our model …

Order And Asymmetry In Jammed Systems, Zhusong Li

Dissertations, Theses, and Capstone Projects

Granular matter is composed of particles that are big enough that thermal effects may be neglected. We studied both granular flow and granular statics using numerical simulation. In granular flow, we simulated 2D granular flow in a hopper. A hopper is a container with an opening at the bottom. Simulated disks are placed in the hopper with the bottom closed and then released. We developed a new tangential force model to simulate hopper flow, that matches experiments and shows that the output flux is proportional to the bottom opening size to the 3/2 power. We also see clogging or jamming …

Hybridized Criticality And Elementary Excitations In Lihof4, Haifu Ma

Dissertations, Theses, and Capstone Projects

In this dissertation, I study the magnetic properties of LiHoF₄. Quantum criticality in rare earth ferromagnet LiHoF₄ is complicated by the presence of strong crystal field and hyperfine interactions resulting, e.g., in incomplete mode softening reported by Rønnow et al. We construct a systematic framework for treating elementary excitations in this material across the phase diagram. These excitations interpolate between purely electronic, nuclear and lattice modes and exhibit two-types of quantum critical softening, both complete (as anticipated by elementary treatments, see e.g. Sachdev) but also incomplete, in close correspondence with nuclear scattering results.

Ordering And Topological Defects In Solids With Quenched Randomness, Thomas Chapman Proctor

Dissertations, Theses, and Capstone Projects

We explore multiple different examples of quenched randomness in systems with a continuous order parameter. In all these systems, it is shown that understanding the effects of topology is critical to the understanding of the effects of quenched randomness.

We consider n-component fixed-length order parameter interacting with a weak random field in d = 1,2,3 dimensions. Relaxation from the initially ordered state and spin-spin correlation functions have been studied on lattices containing hundreds of millions sites. At n - 1 < d presence of topological structures leads to metastability, with the final state depending on the initial condition. At n …

Optimal Measurements Tasks And Their Physical Realizations, Vadim Yerokhin

Dissertations, Theses, and Capstone Projects

This thesis reflects works previously published by the author and materials hitherto unpublished on the subject of quantum information theory. Particularly, results in optimal discrimination, cloning, and separation of quantum states, and their relationships, are discussed.

Our interest lies in the scenario where we are given one of two quantum states prepared with a known a-priori probability. We are given full information about the states and are assigned the task of performing an optimal measurement on the incoming state. Given that none of these tasks is in general possible to perform perfectly we must choose a figure of merit to …

Accurate Deterministic Solutions For The Classic Boltzmann Shock Profile, Yubei Yue

Dissertations, Theses, and Capstone Projects

The Boltzmann equation or Boltzmann transport equation is a classical kinetic equation devised by Ludwig Boltzmann in 1872. It is regarded as a fundamental law in rarefied gas dynamics. Rather than using macroscopic quantities such as density, temperature, and pressure to describe the underlying physics, the Boltzmann equation uses a distribution function in phase space to describe the physical system, and all the macroscopic quantities are weighted averages of the distribution function. The information contained in the Boltzmann equation is surprisingly rich, and the Euler and Navier-Stokes equations of fluid dynamics can be derived from it using series expansions. Moreover, …

Propagation Of Non-Stationary Noise In Waveguides, Jonathan Samuel Ben-Benjamin

Dissertations, Theses, and Capstone Projects

This thesis consists of research regarding pulse and noise propagation in dispersive media. The research consists of three parts. In Part I we develop an approach for the propagation of non-stationary noise in waveguides, and in particular, we focus on the two-plate waveguide, which is a standard model for the ocean. he fundamental aim is to obtain the propagation of the space-time autocorrelation function. In our formulation, the noise is described by a Wigner spectrum, from which the autocorrelation function can be obtained. We discuss how to obtain the Wigner spectrum of a noise field from the Wigner spectrum of …

Growth And Characterization Of Type-Ii Submonolayer Zncdte/Zncdse Quantum Dot Superlattices For Efficient Intermediate Band Solar Cells, Siddharth Dhomkar

Dissertations, Theses, and Capstone Projects

In this thesis, we discuss the growth procedure and the characterization results obtained for epitaxially grown submonolayer type-II quantum dot superlattices made of II-VI semiconductors. The goal behind this study is to show the feasibility of this novel material system in fabricating an efficient intermediate band solar cell.

Intermediate band solar cells can potentially have an efficiency of 63.2% under full solar concentration, but the material systems investigated until now are far from optimum and are fraught with growth related issues including low quantum dot densities, presence of wetting layers, strain driven dislocations etc. Here, we have investigated a novel …

Studies On Bell's Theorem, Veli Ugur Guney

Dissertations, Theses, and Capstone Projects

In this work we look for novel classes of Bell's inequalities and methods to produce them. We also find their quantum violations including, if possible, the maximum one.

The Jordan bases method that we explain in Chapter 2 is about using a pair of certain type of orthonormal bases whose spans are subspaces related to measurement outcomes of incompatible quantities on the same physical system. Jordan vectors are the briefest way of expressing the relative orientation of any two subspaces. This feature helps us to reduce the dimensionality of the parameter space on which we do searches for optimization. The …

Friction, Avalanches And Phase Transitions In Granular Media., Aline Hubard

Dissertations, Theses, and Capstone Projects

We explore the microscopic interactions and properties of dry granular materials in the plane using experiments and simulations. We use statistics of this microscopic information to better understand and predict the bulk behavior and evolution of granular materials.

In the first part, we study the geometric structure of mechanically stable packings of frictional disks in configuration space. Our experimental setup contains frictional disks confined in a vertical plane and subject to a series of small amplitude vibrations that compact the system by reducing the friction between contacts during each vibration step. We find that the evolution of the packings forms …

A Static And Dynamic Investigation Of Quantum Nonlinear Transport In Highly Dense And Mobile 2d Electron Systems, Scott A. Dietrich

Dissertations, Theses, and Capstone Projects

Heterostructures made of semiconductor materials may be one of most versatile environments for the study of the physics of electron transport in two dimensions. These systems are highly customizable and demonstrate a wide range of interesting physical phenomena. In response to both microwave radiation and DC excitations, strongly nonlinear transport that gives rise to non-equilibrium electron states has been reported and investigated. We have studied GaAs quantum wells with a high density of high mobility two-dimensional electrons placed in a quantizing magnetic field. This study presents the observation of several nonlinear transport mechanisms produced by the quantum nature of these …

Exploring Non-Equilibrium Dynamics In Time Dependent Density Functional Theory, Kai Luo

Dissertations, Theses, and Capstone Projects

Time-dependent density functional theory (TDDFT) is a method of choice for calculations of excitation spectra and response properties in materials science and quantum chemistry. The many-body problem is mapped into a set of one-body Schrödinger equations, called the Kohn-Sham (KS) equations. In principle, the one-body potential can be chosen such that the density of the interacting system is exactly reproduced by the KS system. However, one component of the one-body potential has to be approximated and is typically "adiabatic". Though in linear response regime adiabatic approximations give quite good spectra, it is important to explore their performances in non-equilibrium dynamics. …

Quantum State Discrimination And Quantum Cloning: Optimization And Implementation, Andi Shehu

Dissertations, Theses, and Capstone Projects

In our work we explore the field of quantum state discrimination and quantum cloning. Recently the problem of optimal state discrimination with a Fixed Rate of Inconclusive Outcomes (FRIO strategy) has been solved for two pure quantum states and a few other highly symmetric cases. An optical implementation to FRIO for pure states is provided. The physical implementation can be carried out with the use of a six-port interferometer constructed with optical fibers beam splitters, phase shifters and mirrors. The input states are composed of qubits which are realized as photons in the dual-rail representation. The non-unitary measurements are carried …

Disorder Effects In Charge Transport And Spin Response Of Topological Insulators, Lukas Zhonghua Zhao

Dissertations, Theses, and Capstone Projects

Topological insulators are a class of solids in which the non-trivial inverted bulk band structure gives rise to metallic surface states that are robust against impurity backscattering. First principle calculations predicted Bi₂Te₃, Sb₂Te₃ and Bi₂Se₃ to be three-dimensional (3D) topological insulators with a single Dirac cone on the surface. The topological surface states were subsequently observed by angle-resolved photoemission (ARPES) and scanning tunneling microscopy (STM). The investigations of charge transport through topological surfaces of 3D topological insulators, however, have faced a major challenge due to large charge carrier densities in …

De Novo Design And Engineering Of Functional Metal And Porphyrin-Binding Protein Domains, Bernard Howard Everson

Dissertations, Theses, and Capstone Projects

In this work, I describe an approach to the rational, iterative design and characterization of two functional cofactor-binding protein domains. First, a hybrid computational/experimental method was developed with the aim of algorithmically generating a suite of porphyrin-binding protein sequences with minimal mutual sequence information. This method was explored by generating libraries of sequences, which were then expressed and evaluated for function. One successful sequence is shown to bind a variety of porphyrin-like cofactors, and exhibits light- activated electron transfer in mixed hemin:chlorin e6 and hemin:Zn(II)-protoporphyrin IX complexes. These results imply that many sophisticated functions such as cofactor binding and electron …

Wigner High-Electron-Correlation Regime Of Non-Uniform Density Systems: A Quantal-Density-Functional-Theory Study, Douglas Mortimer Achan

Dissertations, Theses, and Capstone Projects

The Wigner regime of a system of electrons in an external field is characterized by a low electron density and a high electron-interaction energy relative to the kinetic energy. The low correlation regime is in turn described by a high electron density and an electron-interaction energy smaller than the kinetic energy. The Wigner regime of a nonuniform electron density system is investigated via quantal density functional theory (QDFT). Within QDFT, the contributions of electron correlations due to the Pauli exclusion principle, Coulomb repulsion, and correlation-kinetic effects are separately delineated and explicitly defined. The nonuniform electron density system studied is that …

Geometry And Statistics Of Jammed Granular Matter, Mark Robert Kanner

Dissertations, Theses, and Capstone Projects

We use simulations of soft bidisperse disks to determine the properties of jammed packings and investigate the statistical mechanics of these systems. We have created a novel method for the classification of structural subunits of a packing and to calculate relevant physical quantities. The classification scheme is based on a 20 type decomposition of the Delaunay triangles extracted from the centers of the particles. Subunit frequencies are determined from geometrical properties and used to calculate the important macroscopic system quantities co-ordination number, packing fraction, and pressure. These relationships suggest that microscopic particle geometry plays an important role in observed macroscopic …

Strongly-Correlated 2d Electron Systems In Si-Mosfets, Shiqi Li

Dissertations, Theses, and Capstone Projects

Si-MOSFETs are basic building blocks of present-day integrated circuits. Above a threshold gate voltage, a layer of two-dimensional electrons is induced near the silicon-silicon dioxide interface of a Si-MOSFET. According to theory for noninteracting and weakly interacting electrons, no metallic state can exist in two dimensions in zero magnetic field in the limit of zero temperature. However, in strongly interacting electron systems the observation of a resistivity that changes from metallic to insulating temperature dependence has fueled a debate over whether this signals a quantum phase transition to a metallic phase in two dimensions.

In this thesis I will present …

Consequence Management: Evaluating And Developing International Responses To Nuclear And Radiological Disasters, Timothy Taylor

Dissertations and Theses

No abstract provided.