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Full-Text Articles in Physics

Interactions Of Organic Fluorophores With Plasmonic Surface Lattice Resonances, Robert J. Collison Feb 2021

Interactions Of Organic Fluorophores With Plasmonic Surface Lattice Resonances, Robert J. Collison

Dissertations, Theses, and Capstone Projects

It is common knowledge that metals, alloys and pure elements alike, are lustrous and reflective, the more so when a metal surface is flat, polished, and free from oxidation and surface fouling. However, some metals reflect visible light, in the 380 nm to 740 nm range of wavelengths, much more strongly than others. In particular, some metals reflect wavelengths in certain portions of the ultraviolet (UV), visible, and near-infrared (NIR) regime, let us say 200 nm to 2000 nm, while absorbing light strongly in other segments of this range. There are several factors that account for this difference between various ...


Role Of Protonation State Changes And Hydrogen Bonding Around The Oxygen Evolving Complex Of Photosystem Ii, Divya Matta Feb 2021

Role Of Protonation State Changes And Hydrogen Bonding Around The Oxygen Evolving Complex Of Photosystem Ii, Divya Matta

Dissertations, Theses, and Capstone Projects

The mechanism of natural photosynthesis involves the use of solar energy to produce O2 we breathe and food and fuel we intake. This process results in the biological oxidation of water that takes place at room temperature, neutral pH using earth abundant elements Ca and Mn. Understanding how this challenging chemical reaction occurs in photosynthesis can be useful for designing better artificial photosynthetic complexes that can be used as biofuels. My doctoral work is to study the deprotonation and oxidation events elucidating the mechanistic details of proton coupled electron transfer reaction in a photosynthetic protein.

The O2 evolution ...


Third Harmonic Generation: A Method For Visualizing Myelin In The Murine Cerebral Cortex, Michael Redlich Feb 2021

Third Harmonic Generation: A Method For Visualizing Myelin In The Murine Cerebral Cortex, Michael Redlich

Dissertations, Theses, and Capstone Projects

Here we present the use of Third Harmonic Generation (THG) for the label-free imaging of myelinated axons in the murine cerebral cortex. Myelin plays an important role in the processes of learning and disease. However, much of the myelin biology research thus far has focused on white matter tracts where myelin is more visible. Much is still unknown, particularly with regard to myelin in gray matter. First, we engage in THG microscopy using an optical parametric oscillator pumped by a titanium-sapphire laser to demonstrate the utility of the technique for imaging myelin in vivo. Second, we investigate the use of ...


Wave Propagation In Random And Topological Media, Yuhao Kang Sep 2020

Wave Propagation In Random And Topological Media, Yuhao Kang

Dissertations, Theses, and Capstone Projects

This thesis discusses wave propagation in two kinds of systems, random media and topological insulators. In a disordered system, the wave is randomized by multiple scattering. The scattering matrix and associated delay times are powerful tools with which to describe wave transport. We discuss the relation among the Wigner time, the transmission time, and energy density in a lossless or lossy system. We propose the zeros of the transmission matrix and show how to manipulate the zero-transmission mode in a nonunitary system. In a photonic topological insulator, we realize an edge mode and discuss its robustness in the face of ...


Linear And Non-Linear Elastic Constants Of Crystalline Materials From First-Principles Calculations, David Cuffari Sep 2020

Linear And Non-Linear Elastic Constants Of Crystalline Materials From First-Principles Calculations, David Cuffari

Dissertations, Theses, and Capstone Projects

Novel methods based on the use of density functional theory (DFT) calculations are developed and applied to calculate linear and non-linear elastic constants of materials at zero and finite temperature. These methods rely on finite difference techniques and are designed to be general, numerically accurate, and suitable to investigate the thermoelastic properties of anharmonic materials. A first method was developed to compute the third-order elastic constants of crystalline materials at zero temperature, a task that is numerically challenging and is currently undertaken by using approaches typically applicable to cubic and hexagonal crystalline systems. This method relies on numerical differentiation of ...


Particle Dynamics In Anti-De Sitter Space By Eih Method, Jiusi Lei Sep 2020

Particle Dynamics In Anti-De Sitter Space By Eih Method, Jiusi Lei

Dissertations, Theses, and Capstone Projects

Following the work of Einstein, Infeld and Hoffmann, we show that particle dynamics in Anti-de Sitter spacetime can be built up by regarding singularities in spacetime manifold as the source of particles.

Since gauge fields play a foundational role in the action, the singularities are chosen to be point-like instantons. Their winding number, defined by an integration on the spheres surrounding those singularities, will turn out to be related to their masses. And their action, derived from the Chern-Simons forms, will be a co-adjoint orbit action, with group element g ∈ SO(4, 2) describing the collective coordinates of the particle ...


An Accurate Solution Of The Self-Similar Orbit-Averaged Fokker-Planck Equation For Core-Collapsing Isotropic Globular Clusters: Properties And Application, Yuta Ito Sep 2020

An Accurate Solution Of The Self-Similar Orbit-Averaged Fokker-Planck Equation For Core-Collapsing Isotropic Globular Clusters: Properties And Application, Yuta Ito

Dissertations, Theses, and Capstone Projects

Hundreds of dense star clusters exist in almost all galaxies. Each cluster is composed of approximately ten thousand through ten million stars. The stars orbit in the clusters due to the clusters' self-gravity. Standard stellar dynamics expects that the clusters behave like collisionless self-gravitating systems on short time scales (~ million years) and the stars travel in smooth continuous orbits. Such clusters temporally settle to dynamically stable states or quasi-stationary states (QSS). Two fundamental QSS models are the isothermal- and polytropic- spheres since they have similar structures to the actual core (central part) and halo (outskirt) of the clusters. The two ...


Emulating Condensed Matter Systems In Classical Wave Metamaterials, Matthew Weiner Sep 2020

Emulating Condensed Matter Systems In Classical Wave Metamaterials, Matthew Weiner

Dissertations, Theses, and Capstone Projects

One of the best tools we have for the edification of physics is the analogy. When we take our classical set of states and dynamical variables in phase space and treat them as vectors and Hermitian operators respectively in Hilbert space through the canonical quantization, we lose out on a lot of the intuition developed with the previous classical physics. With classical physics, through our own experiences and understanding of how systems should behave, we create easy-to-understand analogies: we compare the Bohr model of the atom to the motion of the planets, we compare electrical circuits to the flow of ...


Control Of Molecular Energetics And Transport Via Strong Light-Matter Interaction, Rong Wu Sep 2020

Control Of Molecular Energetics And Transport Via Strong Light-Matter Interaction, Rong Wu

Dissertations, Theses, and Capstone Projects

Strong light-matter coupling in excitonic systems results in the formation of half-light half-matter quasiparticles called exciton polaritons. These hybrid quasiparticles take on the best of both systems, namely, the long-range propagation and coherence arising from the photonic component and the nonlinear interaction from the excitonic component. We develop methods for making high quality factor cavities and investigate the potential applications of these strongly coupled states arising specifically in organic molecular systems.

In the first project we investigate the potential of organic dye molecules to undergo condensation in an optical cavity at room temperature. The second study involves the use of ...


Snow-Albedo Feedback In Northern Alaska: How Vegetation Influences Snowmelt, Lucas C. Reckhaus Aug 2020

Snow-Albedo Feedback In Northern Alaska: How Vegetation Influences Snowmelt, Lucas C. Reckhaus

School of Arts & Sciences Theses

This paper investigates how the snow-albedo feedback mechanism of the arctic is changing in response to rising climate temperatures. Specifically, the interplay of vegetation and snowmelt, and how these two variables can be correlated. This has the potential to refine climate modelling of the spring transition season. Research was conducted at the ecoregion scale in northern Alaska from 2000 to 2020. Each ecoregion is defined by distinct topographic and ecological conditions, allowing for meaningful contrast between the patterns of spring albedo transition across surface conditions and vegetation types. The five most northerly ecoregions of Alaska are chosen as they encompass ...


Qwasi: The Quantum Walk Simulator, Warren V. Wilson Aug 2020

Qwasi: The Quantum Walk Simulator, Warren V. Wilson

School of Arts & Sciences Theses

As quantum computing continues to evolve, the ability to design and analyze novel quantum algorithms becomes a necessary focus for research. In many instances, the virtues of quantum algorithms only become evident when compared to their classical counterparts, so a study of the former often begins with a consideration of the latter. This is very much the case with quantum walk algorithms, as the success of random walks and their many, varied applications have inspired much interest in quantum correlates. Unfortunately, finding purely algebraic solutions for quantum walks is an elusive endeavor. At best, and when solvable, they require simple ...


Generating Entanglement With The Dynamical Lamb Effect, Mirko Amico Jun 2020

Generating Entanglement With The Dynamical Lamb Effect, Mirko Amico

Dissertations, Theses, and Capstone Projects

According to quantum field theory, the vacuum is filled with virtual particles which can be turned into real ones under the influence of external perturbations. Phenomena of this kind are commonly referred to as quantum vacuum phenomena. Several quantum vacuum phenomena related to the peculiar nature of the quantum vacuum have been predicted, some of which, such as the Lamb shift and the Casimir effect, have been experimentally found. Other examples of quantum vacuum phenomena include the Unruh effect, the dynamical Casimir effect and the dynamical Lamb effect. The dynamical Lamb effect was first predicted by considering the situation of ...


Small-X Qcd Calculations With A Biased Ensemble, Gary Kapilevich Jun 2020

Small-X Qcd Calculations With A Biased Ensemble, Gary Kapilevich

Dissertations, Theses, and Capstone Projects

In this dissertation, I will argue that we can study functional fluctuations in unintegrated gluon distributions, in the MV model as well as JIMWLK, using reweighting techniques, which will allow me to calculate QCD observables with "biased ensembles". This technique will enable me to study rare functional configurations of the gluon distributions, that might have been selected for in, for example, the centrality criteria used by the ATLAS and ALICE collaborations. After a review of these techniques, as well as a review of QCD physics at high energy in general, I will use biased ensembles to compute observables in two ...


At The Interface Of Algebra And Statistics, Tai-Danae Bradley Jun 2020

At The Interface Of Algebra And Statistics, Tai-Danae Bradley

Dissertations, Theses, and Capstone Projects

This thesis takes inspiration from quantum physics to investigate mathematical structure that lies at the interface of algebra and statistics. The starting point is a passage from classical probability theory to quantum probability theory. The quantum version of a probability distribution is a density operator, the quantum version of marginalizing is an operation called the partial trace, and the quantum version of a marginal probability distribution is a reduced density operator. Every joint probability distribution on a finite set can be modeled as a rank one density operator. By applying the partial trace, we obtain reduced density operators whose diagonals ...


Generalized Four-Dimensional Effective Hadronic Supersymmetry Based On Quantum Chromodynamics (Qcd), Enxi Yu Jun 2020

Generalized Four-Dimensional Effective Hadronic Supersymmetry Based On Quantum Chromodynamics (Qcd), Enxi Yu

Dissertations, Theses, and Capstone Projects

New discovery in multiple laboratories around the globe has shown a supersymmetry between hadrons—baryons and mesons. In order to generalize the phenomenological hadronic supersymmetry, the spin-flavor SU(6) symmetry need an extension. This thesis present how we can extend SU(6) symmetry so that hadronic supersymmetry can be included. In the future, this extension can be also applied to pentaquark and tetraquark bags, for which there is an ongoing research in laboratories.


Proton Pumping Mechanism In Cytochrome C Oxidase, Xiuhong Cai Jun 2020

Proton Pumping Mechanism In Cytochrome C Oxidase, Xiuhong Cai

Dissertations, Theses, and Capstone Projects

Cytochrome c Oxidase (CcO), is the terminal electron acceptor in the membrane bound aerobic respiratory chain. It reduces O2 to water. The energy released by this reaction is stored by pumping protons from the high pH, N-side of the membrane to the low pH, P-side. The generated proton gradient provides the motive force for synthesis of ATP by the ATP synthase.

Building a proton gradient across the membrane requires that proton transport must occur along controllable proton pathways to prevent proton leakage to the N-side. It has been suggested that CcO function requires proton transfer channels in both the ...


Duality In A Model Of Layered Superfluids And Sliding Phases, Steven Vayl Feb 2020

Duality In A Model Of Layered Superfluids And Sliding Phases, Steven Vayl

Dissertations, Theses, and Capstone Projects

The intent of my project is to determine if the proposal of sliding phases in XY layered systems has physical ground. It will be done by comparing numerical and analytical results for a layered XY models. Sliding phases were first proposed in the context of DNA complexes and then extended to XY models, 1D coupled wires and superfluid films. The existence of the sliding phase would mean that there is a phase transition from 3D to 2D behavior. Such systems have been studied both in the clean case and with disorder. The idea of the sliding phases is based on ...


Density Functional Theory Study Of Two-Dimensional Boron Nitride Films, Pradip R. Niraula Feb 2020

Density Functional Theory Study Of Two-Dimensional Boron Nitride Films, Pradip R. Niraula

Dissertations, Theses, and Capstone Projects

Since graphene was isolated in 2004, the number of two-dimensional (2D) materials and their scientific relevance have grown exponentially. Besides graphene, one of the most important and technolocially promizing 2D materials that has emerged in recent years is hexagonal boron nitride, in its monolayer or multilayer form. In my thesis work, I used density functional theory (DFT) calculations to investigate the properties of boron nitride films. In particular, I first studied the properties (i.e. formation energy, defect states, and structure) of point charged defects in monolayer and bilayer hexagonal boron nitride, and subsequently, I focused on the linear and ...


Ii-Vi Type-Ii Quantum Dot Superlattices For Novel Applications, Vasilios Deligiannakis Feb 2020

Ii-Vi Type-Ii Quantum Dot Superlattices For Novel Applications, Vasilios Deligiannakis

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. We have investigated the spin dynamics of ZnSe layers with embedded type-II ZnTe quantum dots and the use of (Zn)CdTe/ZnCdSe QDs for intermediate band solar cell (IBSC). Samples with a higher quantum dot density exhibit longer electron spin lifetimes, up to ~1 ns at low temperatures. Tellurium isoelectronic centers, which form in the ZnSe spacer regions as a result of the growth conditions, were also probed. A new growth sequence for type-II (Zn ...


On Different Parametrizations Of Feynman Integrals, Ray Daniel Sameshima Sep 2019

On Different Parametrizations Of Feynman Integrals, Ray Daniel Sameshima

Dissertations, Theses, and Capstone Projects

In this doctoral thesis, we discuss and apply advanced techniques for the calculations of scattering amplitudes which, on the one hand, allow us to compute cross sections and differential distributions at high precision and, on the other hand, give us deep mathematical insights on the mathematical structures of Feynman integrals.

We start by presenting phenomenological calculations relevant for the experimental analyses at the Large Hadron Collider. We use the resummation of soft gluon emission corrections to study the associated production of a top pair and a Z boson to next-to-next-to-leading logarithmic accuracy, and compute the total cross section and differential ...


Optical And Collective Properties Of Excitons In 2d Semiconductors, Matthew N. Brunetti Sep 2019

Optical And Collective Properties Of Excitons In 2d Semiconductors, Matthew N. Brunetti

Dissertations, Theses, and Capstone Projects

We study the properties of excitons in 2D semiconductors (2DSC) by numerically solving the Schr\"{o}dinger equation for an interacting electron and hole in the effective mass approximation, then calculating optical properties such as the transition energies, oscillator strengths, and absorption coefficients. Our theoretical approach allows us to consider both direct excitons in monolayer (ML) 2DSC and spatially indirect excitons in heterostructures (HS) consisting of two 2DSC MLs separated by few-layer insulating hexagonal boron nitride (h-BN). In particular, we study indirect excitons in TMDC HS, namely MoS2, MoSe2, WS2, and WSe2; both direct and ...


Stability And Application Of The K-Core Dynamical Model To Biological Networks, Francesca Beatrice Arese Lucini Sep 2019

Stability And Application Of The K-Core Dynamical Model To Biological Networks, Francesca Beatrice Arese Lucini

Dissertations, Theses, and Capstone Projects

The objective of the dissertation is to illustrate the importance of the k-core dynamical model, by first presenting the stability analysis of the nonlinear k-core model and compare its solution to the most widely used linear model. Second, I show a real world application of the k-core model to describe properties of neural networks, specifically, the transition from conscious to subliminal perception.


Exciton Polaritons In Two-Dimensional Transition Metal Dichalcogenides, Jie Gu Sep 2019

Exciton Polaritons In Two-Dimensional Transition Metal Dichalcogenides, Jie Gu

Dissertations, Theses, and Capstone Projects

Strong interaction between photons and excitons in semiconductors results in the formation of half-light half-matter quasiparticles termed exciton-polaritons. Owing to their hybrid character, they inherit the strong interparticle interaction from their excitonic (matter) component via Coulomb interaction while the photonic component lends the small mass (~105 times lighter than free electrons) and long propagation distances. Additionally, exciton-polaritons also carry properties of the host material excitons such as spin and valley polarization and can be probed via the photons that leak out of the cavities since the photon carries all the information owing to conservation laws. Since the first demonstration ...


Interplay Of Magnetism, Superconductivity, And Topological Phases Of Matter, Cody Youmans Sep 2019

Interplay Of Magnetism, Superconductivity, And Topological Phases Of Matter, Cody Youmans

Dissertations, Theses, and Capstone Projects

Multiband superconducting materials, such as iron pnictides and doped topological insulators, have shown to be particularly promising platforms for realizing unconventional electronic behavior of both fundamental and practical importance. Similarly, new innovations in the engineering of gapped topological phases, like semiconductor based Kitaev chains and topological insulator based heterostructures, have opened new directions for solid-state design. Central to much of the excitement generated by such multifaceted electronic systems is a rich interplay between various inherent structural ordering tendencies and topologically non-trivial properties.

In some classes of pnictides, spin density wave order coexists with superconductivity over a range of doping and ...


Physics And Mathematics Of Graded Quivers, Azeem Hasan Sep 2019

Physics And Mathematics Of Graded Quivers, Azeem Hasan

Dissertations, Theses, and Capstone Projects

A graded quiver with superpotential is a quiver whose arrows are assigned degrees c ∈ {0, 1, · · · , m}, for some integer m ≥ 0, with relations generated by a superpotential of degree m − 1. For m = 0, 1, 2, 3 they often describe the open string sector of D-brane systems; in particular, they capture the physics of D(5 − 2m)-branes at local Calabi-Yau (CY) (m + 2)- fold singularities in type IIB string theory. We introduce m-dimers, which fully encode the m-graded quivers and their superpotentials, in the case in which the CY (m + 2)-folds are toric. A key result is ...


Sequential Discrimination Between Non-Orthogonal Quantum States, Dov L. Fields Sep 2019

Sequential Discrimination Between Non-Orthogonal Quantum States, Dov L. Fields

Dissertations, Theses, and Capstone Projects

The problem of discriminating between non-orthogonal states is one that has generated a lot of interest. This basic formalism is useful in many areas of quantum information. It serves as a fundamental basis for many quantum key distribution schemes, it functions as an integral part of other quantum algorithms, and it is useful in experimental settings where orthogonal states are not always possible to generate. Additionally, the discrimination problem reveals important fundamental properties, and is intrinsically related to entanglement. In this thesis, the focus is on exploring the problem of sequentially discriminating between non-orthogonal states. In the simplest version these ...


Inference Of Language Functional Network In Healthy, Cancerous And Bilingual Brains By Fmri And Network Modeling, Qiongge Li Sep 2019

Inference Of Language Functional Network In Healthy, Cancerous And Bilingual Brains By Fmri And Network Modeling, Qiongge Li

Dissertations, Theses, and Capstone Projects

We study the underlying mechanism by which language processing occurs in the human brain using inference methods on functional magnetic resonance imaging data. The data analyzed stems from several cohorts of subjects; a monolingual group, a bilingual group, a healthy control group and one diseased case. We applied a complex statistical inference pipeline to determine the network structure of brain components involved with language. This healthy network reveals a fully connected triangular relationship between the pre-Supplementary Motor Area (pre-SMA), the Broca's Area (BA), and the ventral Pre-Motor Area (PreMA) in the left hemisphere. This "triangle'' shows consistently in all ...


Coulomb Excitation And Transport Properties Of Monolayer Graphene And The Alpha-T3 Lattice, Dipendra Dahal Sep 2019

Coulomb Excitation And Transport Properties Of Monolayer Graphene And The Alpha-T3 Lattice, Dipendra Dahal

Dissertations, Theses, and Capstone Projects

In the past few years, I focused my attention in the study of 2D material's behavior, specifically graphene . We investigated several properties of graphene like transmission of particle through a potential barrier and demonstrated the effect of band gap to suppress the Klein tunneling at head on collision, we presented the results to get the criteria of negative refractive index and Klein tunneling through multiple barrier. Next, we have carried out the calculation of polarization function of graphene in the presence of magnetic field. The effect of integer Landau filling factor is shown and the portrayed results are presented ...


Optimization Of Information Storage With Quantum Walks, Gui Zhen Lu Jun 2019

Optimization Of Information Storage With Quantum Walks, Gui Zhen Lu

School of Arts & Sciences Theses

A four-vertex quantum graph was analyzed with the objective of storing the highest ampli- tude of an incoming qubit. The procedure included the use of phase shifters to allow the user to store and release information when he or she chooses. Several parameters, such as the phase shift, location of the phase shifter, the size and shape of the binding graph and initial incoming state were varied independently to optimize the storage capacity of the graph.


Nuclear Magnetic Resonance Characterization Of Dynamics In Novel Electrochemical Materials, Christopher T. Mallia May 2019

Nuclear Magnetic Resonance Characterization Of Dynamics In Novel Electrochemical Materials, Christopher T. Mallia

School of Arts & Sciences Theses

As our daily use of electronics and electronic technology grows, so does the societal need for sustainable, renewable and portable electrical power. To this end, materials of interest in the electrochemical world are needed to advance the frontier of battery science and energy storage technologies so that a safer, more efficient and reliable electrical future can be realized. This work focuses on characterization of materials primarily of interest for use as electrolytes in rechargeable Lithium-Ion Batteries (LIBs). Despite their extraordinary power, LIB application in certain fields, such as in electric vehicles, has been limited due to performance and safety concerns ...