Physics Commons^™

Parameter Identifiability And Estimation In A 1d Cardiovascular Fluid Dynamics Model, Mitchel J. Colebank

Biology and Medicine Through Mathematics Conference

No abstract provided.

Emergence, Mechanics, And Development: How Behavior And Geometry Underlie Cowrie Seashell Form, Michael G. Levy, Michael R. Deweese

Biology and Medicine Through Mathematics Conference

No abstract provided.

Parameter Estimation For Tear Film Thinning, Rayanne Luke

Biology and Medicine Through Mathematics Conference

No abstract provided.

Verification Of The Vertical Bubble Flow Experiments, Reginald Jones Ii

Theses and Dissertations

Detailed experimental design to support basic pedagogy of flow regimes – single phase liquid, bubbly, slug, annular, dispersed droplet, and single phase vapor – occurring in flow channels of nuclear reactors has been developed for EGMN 203 - Nuclear Engineering Practicum offering at Virginia Commonwealth University’s Department of Mechanical and Nuclear Engineering. The laboratory instruction will be used to help students forming ideas and understanding flow regimes occurring in nuclear engineering applications. We designed and constructed four water columns to act as surrogates for water channels in a nuclear reactor. Each column was used for a different experiment: salted versus …

Electric Field Control Of Fixed Magnetic Skyrmions For Energy Efficient Nanomagnetic Memory, Dhritiman Bhattacharya

Theses and Dissertations

To meet the ever-growing demand of faster and smaller computers, increasing number of transistors are needed in the same chip area. Unfortunately, Silicon based transistors have almost reached their miniaturization limits mainly due to excessive heat generation. Nanomagnetic devices are one of the most promising alternatives of CMOS. In nanomagnetic devices, electron spin, instead of charge, is the information carrier. Hence, these devices are non-volatile: information can be stored in these devices without needing any external power which could enable computing architectures beyond traditional von-Neumann computing. Additionally, these devices are also expected to be more energy efficient than CMOS devices …

Sparsity And Weak Supervision In Quantum Machine Learning, Seyran Saeedi

Theses and Dissertations

Quantum computing is an interdisciplinary field at the intersection of computer science, mathematics, and physics that studies information processing tasks on a quantum computer. A quantum computer is a device whose operations are governed by the laws of quantum mechanics. As building quantum computers is nearing the era of commercialization and quantum supremacy, it is essential to think of potential applications that we might benefit from. Among many applications of quantum computation, one of the emerging fields is quantum machine learning. We focus on predictive models for binary classification and variants of Support Vector Machines that we expect to be …

The Design Of A New Vaginal Applicator For Direction Modulated Brachytherapy (Dmbt) Using Geant4 Monte Carlo Simulation Code, Moeen Meftahi

Theses and Dissertations

Purpose: Anisotropy of the 192Ir source causes a lack of dose coverage at the apex in HDR vaginal cylinder brachytherapy (VC BT). In this study, we took advantage of the GEANT4 Monte Carlo (MC) simulation code to design a new DMBT vaginal applicator so that it maintains the dose coverage of the current vaginal cylinder at periphery everywhere while improving the apex coverage. In addition, since current treatment planning systems (TPS) considers the whole environment as water according to TG43 formalism, based on the capability of the MC in the calculation of dose in the material, the effect of inhomogeneity …

Application Of Optical Trapping To Obtain Single-Source Str Profiles From Forensically Relevant Body Fluid Mixtures With Modified Dna Analysis Workflow, Benjamin J. O'Brien

Master of Science in Forensic Science Directed Research Projects

Current methods of mixture separation in forensic DNA laboratories typically deconvolute the mixture after analysis using statistical analysis or probabilistic genotyping. To save time and effort of labs already backlogged, a method to separate mixtures on a cellular level before analysis needs to be developed. Optical trapping is a method that uses a focused 1064 nm laser to manipulate cells. Previous research has shown that approximately 50 spermatozoa or 15 leukocytes from a liquid sample are required to produce a full STR DNA profile. It was found that the number of spermatozoa required remains constant when the method of sample …

Non-Covalent And Covalent Interactions Between Phenylacetylene And Quinoline Radical Cations With Polar And Non-Polar Molecules In The Gas Phase, Adam C. Pearcy

Theses and Dissertations

Gas phase molecular clusters present an ideal medium for observing factors that drive chemical reactions without outside interferences from excessive solvent molecules. Introducing an ion into the cluster promotes ion-molecule interactions that may manifest in a variety of non-covalent or even covalent binding motifs and are of significant importance in many fields including atmospheric and astronomical sciences. For instance, in outer space, molecules are subject to ionizing radiation where ion-molecule reactions become increasingly competitive to molecule-molecule interactions. To elucidate individual ion-molecule interaction information, mass spectrometry was used in conjunction with appropriate theoretical calculations.

Three main categories of experiment were conducted …

Theoretical Studies Of The Structure And Stability Of Metal Chalcogenide Crntem (1≤N≤6, 1≤M≤8) Clusters, Fnu Sweta Prabha

Theses and Dissertations

In the presented work, first principle studies on electronic structure, stability, and magnetic properties of metal chalcogenide, Cr_nTe_m clusters have been carried out within a density functional framework using generalized gradient functions to incorporate the exchange and correlation effects. The energetic and electronic stability was investigated, and it was found that they are not always correlated as seen in the cluster Cr₆Te₈ which has smaller gap between its HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital) and a high electron affinity of 3.39 eV indicating lower electronic stability whereas higher fragmentation …

Optimizing Gas Mixture Composition For The Rtpc Detector For Bonus 12 At Jefferson Lab., Joshua H. Lehman

Theses and Dissertations

The main objective of this thesis is to perform a study of and optimize the most direct and practical gas mixture composition inside the Radial Time Projection Chamber for the Barely-Offshell Nucleon Structure (BONuS 12) detector for use in the CLAS 12 detector in Experimental Hall B at Thomas Jefferson National Accelerator Facility (JLab). The optimization of these conditions will enhance the performance and resolution of the detector. The original BONuS 6 experiment utilized a gas composition of 80 % He and 20% Dimethyl Ether (DME). With the extensive 12 GeV energy upgrade constructed at JLab and the new BONuS …

The Structure And Stability Of Cationic Metal-Benzene Clusters, Daniel P. Rabayda

Theses and Dissertations

We have investigated the size-dependent stability and structure of benzene, aluminum-benzene, and vanadium-benzene clusters. Motivated by gas-phase experimental studies performed by an experimental collaborator, we have used first-principle electronic structure methods to identify the structure of Al⁺(Bz)_n, V⁺(Bz)_n, and Bz_n clusters. Our studies reveal that cationic aluminum-benzene clusters have a magic number of 13, and that its high stability may be understood by analyzing the structure of the cluster. We also investigate the structure of vanadium-benzene clusters which have a magic number of 2. Here I examine the benzene-cation and benzene-benzene …

Pharmacodynamics Of Monoamine Transporter Releasing Agents And Reuptake Inhibitors, Alexa Holloway

Theses and Dissertations

Ligands of the human monoamine transporters encompass a wide range of both illicit and therapeutic drugs that act upon neural circuitry related to reward, motivation, and the processing of salient stimuli. The present study utilizes two methods for analyzing transporter substrates and inhibitors in order to characterize activity and assess potency. The first measures transient changes in intracellular calcium as a surrogate for transporter activity by harnessing the electrical coupling of monoamine transporters and L-type calcium channels. This is used to analyze novel chimera of the strong hDAT inhibitors methylphenidate and ��-PPP in order to assess the contribution of specific …

Searching For Clean Observables In $B -> D* /Tau- \Bar{\Nu}_{\Tau}$ Decays, Michael D. Williams Jr.

Theses and Dissertations

In this thesis, the clean angular observables in the $\bar{B} \to D^{*+} \ell^- \bar{\nu}_{\ell}$ angular distribution is studied. Similar angular observables are widely studied in $B \to K^* \mu^+ \mu^-$ decays. We believed that these angular observables may have different sensitivities to different new physics structures.

Electronic And Geometric Structure Of Alnom And Alnom +, Albert R. Armstrong

Theses and Dissertations

Generally, the electronic stability of aluminum clusters is associated with either closed electronic shells of delocalized electrons, or aluminum in the +3 state. To explore alternative routes for electronic stability in aluminum oxide clusters, theoretical methods were used to examine the geometric and electronic structure of Al_nO_m (2≤n≤7; 1≤m≤10) clusters. Two types of electronically stable clusters with large HOMO-LUMO gaps were identified the first being Al_2nO_3m clusters with a +3 oxidation state on the aluminum, and the second being planar clusters such as Al₄O₄, Al₅O₃, Al …

An Introduction To Supersymmetric Quantum Mechanics, Vincent R. Siggia

Theses and Dissertations

In this thesis, the general framework of supersymmetric quantum mechanics and the path integral approach will be presented (as well as the worked out example of the supersymmetric harmonic oscillator). Then the theory will be specialized to the case of supersymmetric quantum mechanics on Riemannian manifolds, which will start from a supersymmetric Lagrangian for the general case and the special case for S2. Afterwards, there will be a discussion on the superfield formalism. Concluding this thesis will be the Hamiltonian formalism followed by the inclusion of deforma- tions by potentials.

Electronic Structure Of Cathode Materials In Lithium Ion Batteries, John M. Swanlund

Theses and Dissertations

Lithium ion batteries are ubiquitous in modern life, from powering hand-held electronic devices to electric vehicles. And with the necessary drive toward renewable energy sources like solar and wind, electricity storage for the grid promises to drive up the demand for higher performing, less expensive, safer, and more environmentally friendly secondary batteries. Recent research has theorized that replacing halogens in batteries’ electrolytes with non-halogens can yield desirable performance characteristics while eliminating the most dangerous and problematic chemicals. This thesis explores the possibility that a similar approach can be taken with the cathodes of lithium ion batteries. The active material in …

Adhesion At Solid/Liquid Interfaces, Neda Ojaghlou

Theses and Dissertations

The adhesion at solid/liquid interface plays a fundamental role in diverse fields and helps explain the structure and physical properties of interfaces, at the atomic scale, for example in catalysis, crystal growth, lubrication, electrochemistry, colloidal system, and in many biological reactions. Unraveling the atomic structure at the solid/liquid interface is, therefore, one of the major challenges facing the surface science today to understand the physical processes in the phenomena such as surface coating, self-cleaning, and oil recovery applications. In this thesis, a variety of theory/computational methods in statistical physics and statistical mechanics are used to improve understanding of water adhesion …

Straintronic Nanomagnetic Devices For Non-Boolean Computing, Md Ahsanul Abeed

Theses and Dissertations

Nanomagnetic devices have been projected as an alternative to transistor-based switching devices due to their non-volatility and potentially superior energy-efficiency. The energy efficiency is enhanced by the use of straintronics which involves the application of a voltage to a piezoelectric layer to generate a strain which is ultimately transferred to an elastically coupled magnetostrictive nanomaget, causing magnetization rotation. The low energy dissipation and non-volatility characteristics make straintronic nanomagnets very attractive for both Boolean and non-Boolean computing applications. There was relatively little research on straintronic switching in devices built with real nanomagnets that invariably have defects and imperfections, or their adaptation …

Monitoring Software And Charged Particle Identification For The Clas12 Detector, William A. Oliver

Theses and Dissertations

The CEBAF Large Acceptance Spectrometer for the 12 GeV era, known as CLAS12, uses the time of flight (TOF) system to identify charged particles from scattering events between the beam and target. The TOF system is divided into two parts: The Forward time of flight system, and the Central time of flight system. These two sub-systems subtend different polar angles of the detector geometry for wide acceptance of scattered particles. Reconstruction is the service used to identify particles from the interactions between the beam and target, called as a vertex or the point where the interaction occurs. The vertex position …

Inference And Control In Regulatory Genomics, Siddharth Sharma

Biology and Medicine Through Mathematics Conference

No abstract provided.

Elucidating The Action Of A Regulatory Lipid Ligand Via Molecular Simulation: Cholesterol Swarms And The Inwardly Rectifying Potassium Channel, Belinda Akpa, Nicolas Barbera, Irena Levitan

Biology and Medicine Through Mathematics Conference

No abstract provided.

Motion-Induced Artifact Mitigation And Image Enhancement Strategies For Four-Dimensional Fan-Beam And Cone-Beam Computed Tomography, Matthew J. Riblett

Theses and Dissertations

Four dimensional imaging has become part of the standard of care for diagnosing and treating non-small cell lung cancer. In radiotherapy applications 4D fan-beam computed tomography (4D-CT) and 4D cone-beam computed tomography (4D-CBCT) are two advanced imaging modalities that afford clinical practitioners knowledge of the underlying kinematics and structural dynamics of diseased tissues and provide insight into the effects of regular organ motion and the nature of tissue deformation over time. While these imaging techniques can facilitate the use of more targeted radiotherapies, issues surrounding image quality and accuracy currently limit the utility of these images clinically.

The purpose of …

Evaluation And Adaptation Of Live-Cell Interferometry For Applications In Basic, Translational, And Clinical Research, Kevin A. Leslie

Theses and Dissertations

Cell mass is an important indicator of cell health and status. A diverse set of techniques have been developed to precisely measure the masses of single cells, with varying degrees of technical complexity and throughput. Here, the development of a non-invasive, label-free optical technique, termed Live-Cell Interferometry (LCI), is described. Several applications are presented, including an evaluation of LCI’s utility for assessing drug response heterogeneity in patient-derived melanoma lines and the measurement of CD3+ T cell kinetics during hematopoietic stem cell transplantation. The characterization of mast cells during degranulation, the measurement of viral reactivation kinetics in Kaposi’s Sarcoma, and drug …

Kinetic Monte Carlo Simulation Of Binary Alloys, Timothy Craig Marshall

Theses and Dissertations

There are many tools to simulate physical phenomena. Generally, the simulation technique is defined by the size of the simulation area. Two well know techniques for simulating atom dynamics are kinetic Monte Carlo (kMC) and molecular dynamics (MD). In this work we simulate physical vapor deposition of binary metallic systems using the kMC technique. A sufficient quantity of atoms are deposited so that morphological features can be observed. Where kMC has fallen short we have used MD to supplement our results.

Neutronics Studies On The Nist Reactor Using The Ga Leu Fuel, Kyle A. Britton

Theses and Dissertations

The National Bureau of Standards Reactor (NBSR) located on the National Institute of Standards and Technology (NIST) Gaithersburg campus, is currently underway of fuel conversion from high enriched uranium (HEU) fuel to low enriched uranium (LEU) fuel. One particular challenging part of the conversion of the NBSR is the high average flux level (2.5×10¹⁴ n/cm²-s) required to maintain experimental testing capabilities of the reactor, without significant changes to the external structures of the reactor. Recently the General Atomics (GA) Training Research Isotopes General Atomics (TRIGA) fuel has shown some promising features as a LEU candidate for the …

Photoluminescence From Gan Co-Doped With C And Si, Mykhailo Vorobiov

Theses and Dissertations

This thesis devoted to the experimental studies of yellow and blue luminescence (YL and BL relatively) bands in Gallium Nitride samples doped with C and Si. The band BL_C was at first observed in the steady-state photoluminescence spectrum under high excitation intensities and discerned from BL1 and BL2 bands appearing in the same region of the spectrum. Using the time-resolved photoluminescence spectrum, we were able to determine the shape of the BL_C and its position at 2.87 eV. Internal quantum efficiency of the YL band was estimated to be 90\%. The hole capture coefficient of the BL_{C …}

Geodesic Structure In Schwarzschild Geometry With Extensions In Higher Dimensional Spacetimes, Ian M. Newsome

Theses and Dissertations

From Birkoff's theorem, the geometry in four spacetime dimensions outside a spherically symmetric and static, gravitating source must be given by the Schwarzschild metric. This metric therefore satisfies the Einstein vacuum equations. If the mass which gives rise to the Schwarzschild spacetime geometry is concentrated within a radius of r=2M, a black hole will form. Non-accelerating particles (freely falling) traveling through this geometry will do so along parametrized curves called geodesics, which are curved space generalizations of straight paths. These geodesics can be found by solving the geodesic equation. In this thesis, the geodesic structure in the Schwarzschild geometry …

Warp Drive Spacetimes, Nicholas A.S. Driver

Theses and Dissertations

The concept of faster than light travel in general relativity is examined, starting with a review of the Alcubierre metric. This spacetime, although incredible in its implications, has certain unavoidable problems which are discussed in detail. It is demonstrated that in order to describe faster than light travel without any ambiguities, a coordinate independent description is much more convenient. An alternative method of describing superluminal travel is then proposed, which has similarities to the Krasnikov tube.

Optimization Of Cardiac Pacing Stimulation By Current Configuration –A Theoretical, Numerical And Experimental Study., Flavio H. Fenton, Hila Dvir, Neil Hardy

Biology and Medicine Through Mathematics Conference

No abstract provided.