Physical Sciences and Mathematics Commons^™

Manipulative, Dark, And Unethical Design Practices In Ui & Ux Design, Ryan Edward Brown

Honors Theses

This thesis examines the pervasive and detrimental effects of manipulative user interface and user experience design (UI/UX) practices on individuals and society. Focusing on three critical areas – accessibility, dark patterns, and polarization – the study employs a mixed-methods approach, combining findings from a comprehensive literature review, an analysis of specific design patterns and methods, and a survey of user experiences.
The literature review covers topics such as the importance of accessibility in design education, the prevalence of dark patterns in mobile and desktop sites, the role of personalization algorithms in shaping user experiences, and the formation of echo chambers …

Computational Imaging For Shape Understanding, Yuqi Ding

LSU Doctoral Dissertations

Geometry is the essential property of real-world scenes. Understanding the shape of the object is critical to many computer vision applications. In this dissertation, we explore using computational imaging approaches to recover the geometry of real-world scenes. Computational imaging is an emerging technique that uses the co-designs of image hardware and computational software to expand the capacity of traditional cameras. To tackle face recognition in the uncontrolled environment, we study 2D color image and 3D shape to deal with body movement and self-occlusion. Especially, we use multiple RGB-D cameras to fuse the varying pose and register the front face in …

The Fermilab Spinquest Experiment: Commissioning And Plans Toward Production, Nuwan Chaminda Gunawardhana Waduge

Theses and Dissertations

E1039/SpinQuest, a transversely-polarized Drell-Yan experiment at Fermilab, plans to use the 120 GeV proton beam and polarized NH3 and ND3 cryogenic targets to study azimuthal asymmetries in dimuon production to extract the magnitude as well as sign of the sea quarks Sivers functions. The SpinQuest spectrometer is optimized to detect oppositely-charged muons with a series of tracking chambers and hodoscope stations. The scope of this manuscript is to highlight the physics goals and the experimental setup with a focus on the ongoing debugging and training of one of the tracking systems, mainly drift chambers, as preparation for the upcoming commissioning …

Polarization Properties Of Millisecond Pulsars: Astrophysical Interpretations And Applications, Haley Megan Wahl

Graduate Theses, Dissertations, and Problem Reports

Pulsars are some of the most extreme objects in the universe; their small yet incredibly predictable spin periods coupled with their strong magnetic fields make them ideal laboratories for study. Not only are they interesting objects themselves, but they can also help us probe different astrophysical environments, such as the interstellar magnetic field and the solar corona.

These stars are highly polarized, and that polarization comes into play in various fields of pulsar physics (such as constraining models of pulsar emission), but obtaining that polarization information can be difficult, as the polarization properties of the light can change as the …

A Surrogate Model Of Molecular Dynamics Simulations For Polar Fluids: Supervised Learning Methods For Molecular Polarization And Unsupervised Methods For Phase Classification, Zackerie W. Hjorth

Dissertations, Master's Theses and Master's Reports

Molecular Dynamic (MD) simulation is a standard computational tool in soft matter physics. While very powerful, it is computationally expensive, leading to some simulations taking days or even weeks to complete depending on the size of your computer cluster. Finding computationally cheap surrogate models which can learn the output features of MD simulation is therefore highly motivated. In this report I explore the use of deep neural network ensembles as well as support vector machine regressors as surrogate models for MD simulation. From the output of the surrogate models, we can then employ unsupervised learning methods to get insight into …

Exploring The Impact Of Social Influence Mechanisms And Network Density On Societal Polarization, Justin Mittereder

Student Research Submissions

I present an agent-based model, inspired by the opinion dynamics
(OD) literature, to explore the underlying behaviors that may induce
societal polarization. My agents interact on a social network, in which
adjacent nodes can influence each other, and each agent holds an array
of continuous opinion values (on a 0-1 scale) on a number of separate
issues. I use three measures as a proxy for the virtual society’s “po-
larization:” the average assortativity of the graph with respect to the
agents’ opinions, the number of non-uniform issues, and the number
of distinct opinion buckets in which agents have the same …

Mathematical Modelling & Simulation Of Large And Small Scale Structures In Star Formation, Gianfranco Bino

Electronic Thesis and Dissertation Repository

This thesis aims to study the magnetic and evolutionary properties of stellar objects from the prestellar phase up to and including the late protostellar phase. Many of the properties governing star formation are linked to the core’s physical properties and the magnetic field highly dictates much of the core’s stability.

The thesis begins with the implementation of a fully analytic magnetic field model used to study the magnetic properties governing the prestellar core FeSt 1-457. The model is a direct result of Maxwell’s equations and yields a central-to-surface magnetic field ratio in the equatorial plane in cylindrical coordinates. The model …

Argumentation Stance Polarity And Intensity Prediction And Its Application For Argumentation Polarization Modeling And Diverse Social Connection Recommendation, Joseph Winstead Sirrianni

Graduate Theses and Dissertations

Cyber argumentation platforms implement theoretical argumentation structures that promote higher quality argumentation and allow for informative analysis of the discussions. Dr. Liu’s research group has designed and implemented a unique platform called the Intelligent Cyber Argumentation System (ICAS). ICAS structures its discussions into a weighted cyber argumentation graph, which describes the relationships between the different users, their posts in a discussion, the discussion topic, and the various subtopics in a discussion. This platform is unique as it encodes online discussions into weighted cyber argumentation graphs based on the user’s stances toward one another’s arguments and ideas. The resulting weighted cyber …

Polarization Of Nonlinear Thomson Scattering From A High Intensity Laser Focus, Brittni Tasha Pratt

Theses and Dissertations

Thomson scattering from free electrons in a high-intensity laser focus has been widely studied analytically, but not many measurements of this scattering have been made. We measure polarization-resolved nonlinear Thomson scattering from electrons in a high-intensity laser focus using a parabolic mirror. The weak scattering signal is distinguished from background noise using single-photon detectors and nanosecond time-resolution to distinguish a prompt scattering signal from noise photons. The azimuthal and longitudinal components of the fundamental, second, and third harmonics were measured. Our measurements reasonably match theoretical results, but also show some asymmetry in the emission patterns.

A Spectropolarimetric Study Of Southern Wr + O Binaries, Andrew G. Fullard

Electronic Theses and Dissertations

The classical Wolf-Rayet (WR) state is the evolved stage of a massive star, post main-sequence. They are characterized by their strong emission line spectra and stellar winds that are often more than 10 times denser than that of their progenitor O-type stars, which have mass loss rates of 10^-6 M_Θyr^-1. The evolution of WR stars and their connection to specific types of supernovae (SNe) is an open question. Current theory suggests that rapidly rotating massive stars may be the progenitors of SNe that produce long-duration gamma-ray bursts. The interaction between WR stars and their companion …

Polarization Dependence Of High Order Harmonic Generation From Solids In Reflection And Transmission Geometries, Erin L. Crites

Honors Undergraduate Theses

High harmonic generation (HHG) is a process that occurs when an intense laser interacts with a material and generates new frequencies of light. HHG has many practical applications, namely as a spectroscopy technique and source for high frequency light and attosecond pulses. While HHG has been done extensively in gases, HHG in solids is a relatively new field. Solids are appealing as an HHG medium as they require much simpler equipment and are subsequently much more compact, and thus may have a variety of applications previously inaccessible to gas-phase HHG. However, the generation mechanism of HHG in solids has not …

Polarization Properties Of Airy And Ince-Gaussian Laser Beams, Sean Michael Nomoto

Graduate Theses and Dissertations

The description of polarization states of laser light as linear, circular polarization within the paraxial scalar wave approximation is adequate for most applications. However, this description falls short when considering laser light as an electromagnetic wave satisfying Maxwell's equations. An electric field with a constant unit vector for direction of the field and a space dependent complex scalar amplitude in the paraxial wave approximation does not satisfy Maxwell equations which, in general, requires all three Cartesian components of electric and magnetic fields associated for a nonzero laser beam to be nonzero.

Physical observation of passing a linearly polarized laser through …

Quantifying Complex Systems Via Computational Fly Swarms, Troy Taylor

Senior Theses

Complexity is prevalent both in natural and in human-made systems, yet is not well understood quantitatively. Qualitatively, complexity describes a phenomena in which a system composed of individual pieces, each having simple interactions with one another, results in interesting bulk properties that would otherwise not exist. One example of a complex biological system is the bird flock, in particular, a starling murmuration. Starlings are known to move in the direction of their neighbors and avoid collisions with fellow starlings, but as a result of these simple movement choices, the flock as a whole tends to exhibit fluid-like movements and form …

Peeking Into The Other Half Of The Glass : Handling Polarization In Recommender Systems., Mahsa Badami

Electronic Theses and Dissertations

This dissertation is about filtering and discovering information online while using recommender systems. In the first part of our research, we study the phenomenon of polarization and its impact on filtering and discovering information. Polarization is a social phenomenon, with serious consequences, in real-life, particularly on social media. Thus it is important to understand how machine learning algorithms, especially recommender systems, behave in polarized environments. We study polarization within the context of the users' interactions with a space of items and how this affects recommender systems. We first formalize the concept of polarization based on item ratings and then relate …

Designer Metasurfaces For On Demand Optical Responses, Matthew S. Lepain

Electronic Theses and Dissertations

Nanostructured materials are one of the leading areas in photonics currently. These structures offer almost limitless possibilities in the manipulation of light. Using two different semi-analytical simulation methods, I show a few of the possible properties that these nanostructures possess, including polarization rotation and coupling with electronics.

Disentangling Discourse: Networks, Entropy, And Social Movements, Ryan Gallagher

Graduate College Dissertations and Theses

Our daily online conversations with friends, family, colleagues, and strangers weave an intricate network of interactions. From these networked discussions emerge themes and topics that transcend the scope of any individual conversation. In turn, these themes direct the discourse of the network and continue to ebb and flow as the interactions between individuals shape the topics themselves. This rich loop between interpersonal conversations and overarching topics is a wonderful example of a complex system: the themes of a discussion are more than just the sum of its parts.

Some of the most socially relevant topics emerging from these online conversations …

Fluorescence Polarization Measurements To Probe Alignment Of A Bithiophene Dye In One-Dimensional Channels Of Self-Assembled Phenylethynylene Bis-Urea Macrocycle Crystals, Preecha Kittikhunnatham

Theses and Dissertations

This thesis describes the use of polarized fluorescence microscopy to directly probe guest molecule orientation in bis-urea macrocycle crystals. These macrocycles assemble to afford one-dimensional (1D) microchannels ∼9 Å in diameter that have previously been shown to exhibit normal Fickian diffusion and induce selective reactivity among the confined guest molecules. In the present work, we take advantage of the quasi-1D morphology of fiber-like microcrystals with the extended dimension corresponding to the channel axis to measure excitation and emission polarization values for a bithiophene guest. Guest fluorescence is shown to be polarized along the fiber axis with emission polarization values up …

Calculating The Observable Properties Of Mass Accreting Black Holes, Heather Lee

Undergraduate Research Symposium Posters

My goal is to generalize Chandrasekhar’s formulas to include partial Rayleigh Scattering. In my summer research, I successfully recalculated key tables and solutions from his book and I am working in generalizing his results for use in an infinitely deep electron atmosphere. Here, I will summarize how Chandrasekhar derived his formulas and how to potentially generalize them to include absorption.

Beyond Conventional C-Plane Gan-Based Light Emitting Diodes: A Systematic Exploration Of Leds On Semi-Polar Orientations, Morteza Monavarian

Theses and Dissertations

Despite enormous efforts and investments, the efficiency of InGaN-based green and yellow-green light emitters remains relatively low, and that limits progress in developing full color display, laser diodes, and bright light sources for general lighting. The low efficiency of light emitting devices in the green-to-yellow spectral range, also known as the “Green Gap”, is considered a global concern in the LED industry. The polar c-plane orientation of GaN, which is the mainstay in the LED industry, suffers from polarization-induced separation of electrons and hole wavefunctions (also known as the “quantum confined Stark effect”) and low indium incorporation efficiency that …

Modification Of The Fundamental Properties Of Light Through Interaction With Nanostructured Materials, David W. Keene Ii

Electronic Theses and Dissertations

The field of photonics has been growing rapidly over the last few decades as it has endeavored to harness the potential of nanostructured materials to utilize the energy and momentum of electromagnetic radiation on the nanoscale. Using metal nanostructures provides the ability to take advantage of the sub-field of plasmonics which holds the promise of opening the world to vast increases in computational power by circumventing the limitations of conventional current that plague today’s processors. With a thorough understanding of this subject we also get one step closer to increasing the efficiency of solar technology, developing a finer scale of …

Polarization Charge Density In Strained Graphene, Noah Wilson

Graduate College Dissertations and Theses

Graphene, the world's first truly two-dimensional material, is unique for having an electronic structure described by an effective Lorentz invariant theory. One important consequence is that the ratio or Coulomb energy to kinetic energy is a constant, depending only on conditions within the lattice rather than on the average charge density as in a typical Galilean invariant material. Given this unusual property, a natural question would be how do phenomena, such as screening of a Coulomb impurity, happen in graphene? Moreover, how does the addition of uniaxial strain enhance or diminish this behavior? Here I discuss our work to calculate …

The Effects Of Strain And Vacancies On The Electric And Vibrational Properties Of Ferroelectric Batio3 From First-Principles, Aldo Serge Michael Raeliarijaona

Graduate Theses and Dissertations

The studies of ferroelectricity (FE) are of technological significance because of the multitude of applicable properties that ferroelectric materials exhibit. The mastery, and control of these properties necessitate the knowledge of the fundamental physics governing these insulating materials.

In this dissertation I present the results of first-principles investigations of the behavior of the fundamental ferroelectric properties under strain, and in the presence of vacancies. In the first part I introduce the important FE properties, their common behavior, and their numerous valuable applications. Following this background on FEs, a review of theoretical methods is presented with topics such as: Density Functional …

Spectropolarimetry Of Epsilon Aurigae: Probing Stellar And Disk Atmospheres, Kathleen M. Geise

Electronic Theses and Dissertations

The bright eclipsing binary system epsilon Aurigae offers a unique opportunity to uncover physical mechanisms contributing to disk formation and evolution and to explore the relationship between photospheric anisotropies, stellar pulsation and mass loss. This research contributes to our understanding of stellar evolution in the context of binary stars. The research also offers the opportunity to investigate disk formation and evolution significant to our understanding of protoplanetary disks now seen in many star systems. Lastly, the project considers radiative transfer of polarized light that contributes to diverse fields such as atmospheric studies of exoplanets.

My objective is to understand the …

Constructing The Quantum Steering Ellipsoid Using State Measurement Of Biphotons, Carter Vanderbilt

Senior Projects Spring 2015

This paper investigates a recently discovered geometric representation of two-qubit states, the Quantum Steering Ellipsoid, by exploring quantum state measurements on mixtures of polarization-entangled photons produced using spontaneous parametric down conversion (SPDC). Measurements of the second photon of a mixed biphoton system that are conditioned on observations of the first photon demonstrate all possible Bloch Vectors that the second photon can be collapsed to by way of ''steering,'' which is only possible due to the nonlocal nature of entangled systems. This paper examines methods to experimentally verify the Quantum Steering Ellipsoid as a geometric classification of quantum states.

X-Ray Polarimetry With X-Calibur, Qingzhen Guo

Arts & Sciences Electronic Theses and Dissertations

ABSTRACT

X-Ray Polarimetry with X-Calibur

by

Qingzhen Guo

Doctor of Philosophy in Physics, Washington University in St. Louis,

September, 2014. Professor Henric Krawczynski, Chair

X-ray polarimetry is a prime tool to investigate the unexplored compact sources and to provide crucial information that other techniques can not produce. By measuring the degree and orientation of the polarization of radiation from a cosmic source, unique inferences about the morphology and the magnetic field structure can be made.

Krawczysnki's group at Washington University is working on a uniquely sensitive scattering polarimeter, X-Calibur, to be used in the focal plane of a focusing X-ray …

Measurement Of Polarization Observables PZ, PSZ, And PCZ In Double-Pion Photoproduction Off The Proton, Yuqing Mao

Theses and Dissertations

Meson production from excited nucleons is important in the study of baryon resonances and pion photoproduction is attracting much attention. To date a rather large amount of unpolarized cross-section measurements have been reported for both single- and double-pion photoproduction. However, polarization observables provide complementary information as they probe different combinations of transition amplitudes. The database for polarization observables remains quite sparse. Double-pion photoproduction have been studied in Hall B at Jefferson Lab with linearly polarized tagged photon beams incident on longitudinally polarized protons. The experiment covered center-of-mass energies between 1.4 GeV and 2.3 GeV. The target was a FROzen Spin …

The Continuum Linear Polarization Signature Of Classical Be Stars, Robbie J. Halonen

Electronic Thesis and Dissertation Repository

Classical Be stars are rapidly-rotating, massive stars that exhibit distinct observational characteristics due to the presence of enveloping, equatorial disks of gas. While diligent observation of these objects has established a reliable description of their geometric and kinematic properties, our understanding of classical Be stars remains distressingly limited on the dynamical front. Principally, we lack a satisfactory characterization of the physical process(es) through which the gaseous disks form and dissipate. In order to understand the mechanisms that govern the development of these enigmatic stars, we use computational codes to produce theoretical models of these objects and their environments. We compare …

Inverse Problems In Multiple Light Scattering, John Broky

Electronic Theses and Dissertations

The interaction between coherent waves and material systems with complex optical properties is a complicated, deterministic process. Light that scatters from such media gives rise to random fields with intricate properties. It is common perception that the randomness of these complex fields is undesired and therefore is to be removed, usually through a process of ensemble averaging. However, random fields emerging from light matter interaction contain information about the properties of the medium and a thorough analysis of the scattered light allows solving specific inverse problems. Traditional attempts to solve these kinds of inverse problems tend to rely on statistical …

Magneto-Photonic Crystals For Optical Sensing Applications, Neluka Dissanayake

Dissertations, Master's Theses and Master's Reports - Open

Among the optical structures investigated for optical sensing purpose, a significant amount of research has been conducted on photonic crystal based sensors. A particular advantage of photonic crystal based sensors is that they show superior sensitivity for ultra-small volume sensing. In this study we investigate polarization changes in response to the changes in the cover index of magneto-optic active photonic band gap structures. One-dimensional photonic-band gap structures fabricated on iron garnet materials yield large polarization rotations at the band gap edges. The enhanced polarization effects serve as an excellent tool for chemical sensing showing high degree of sensitivity for photonic …

Polarization Properties Of Maxwell-Gauss Laser Beams, Jessica Patricia Conry

Graduate Theses and Dissertations

Laser beams are wave-like optical disturbances. They are characterized by a dominant direction of propagation and a finite extent transverse to the direction of propagation. Many characteristics of laser beams can be described in terms of a scalar function multiplied by a constant vector, which can be real (for linear polarization) or complex (for elliptical polarization). The scalar function is a solution to the paraxial scalar wave equation. This scalar description, however, fails to describe the polarization and focusing characteristics of laser beams correctly. For a correct accounting of these characteristics, the electric and magnetic fields associated with laser beams …