# Physics Commons™

Articles 1 - 30 of 133

## Full-Text Articles in Physics

Jan 2019

#### Utilizing Log Files For Treatment Planning And Delivery Qa In Radiotherapy, Carl W. Stanhope

##### Wayne State University Theses

Purpose: Monte Carlo-based log file quality assurance (LF-MC QA) is investigated as an alternative method to phantom-based patient-specific quality assurance in radiotherapy (e.g. ArcCHECK QA (AC QA)).

Methods: First, the shortcomings of AC QA were investigated. The sensitivity dependence of ArcCHECK diodes on dose rate (in-field) and energy (primarily out-of-field) was quantified. LF-MC QA was then analyzed on the phantom geometry. Planned (‘Plan’) and LF-reconstructed CS and MC doses were compared with each other and AC measurement via statistical (mean ± StdDev(σ)) and gamma analyses to isolate dosimetric uncertainties and quantify the relative accuracies of AC QA and LF-MC ...

#### Magnetic Moment And Susceptibility Quantification In Mri: Additional Frequency Shifts From Materials And Background Phase Removal Using A Reference Phantom, He Xie

##### Wayne State University Dissertations

The first part of this thesis was to utilize existing methods to remove the unwanted background phase from phantom studies. Magnetic moments of straws filled by three different materials (gadolinium, ferritin, and nanoparticles) with four different concentrations of each material were subsequently quantified at 10 different echo times, with straws perpendicular to the main magnetic field. As the radius of each straw was known, susceptibility was calculated from each measured magnetic moment. Results from different echo times agreed within uncertainties. In addition, near perfect linear relation between quantified susceptibility and concentration was obtained for each material. However, phase values inside ...

Addressing The Proton Radius Puzzle Using Qed-Nrqed Effective Field Theory, Steven Patrick Dye Jan 2018

#### Addressing The Proton Radius Puzzle Using Qed-Nrqed Effective Field Theory, Steven Patrick Dye

##### Wayne State University Dissertations

In 2010 the first extraction of the proton charge radius from muonic hydrogen was found to be five standard deviations away from the regular hydrogen value. Seven years later, this proton radius puzzle still persists, and challenges our understanding of the structure of the proton. An effective field theory analysis using Non-Relativistic Quantum Electrody- namics (NRQED) indicates that the muonic hydrogen result can be interpreted as a large, compared to some model estimates, muon-proton spin-independent contact interaction. The muonic hydrogen result can be tested by a muon-proton scattering experiment, MUSE, that is planned at the Paul Scherrer Institute in Switzerland ...

Applications Of Effective Field Theories To New Physics, Derek Edward Hazard Jan 2018

#### Applications Of Effective Field Theories To New Physics, Derek Edward Hazard

##### Wayne State University Dissertations

We apply an effective field theory approach and argue that lepton flavor violating (LFV) decays M → l1l2 of meson states M with different quantum numbers could be used to put constraints on the Wilson coefficients of effective operators describing LFV interactions at low energy scales. We note that the restricted kinematics of the two-body decay of quarkonium or a heavy quark meson allows us to select operators with particular quantum numbers, significantly reducing the reliance on the single operator dominance assumption that is prevalent in constraining parameters of the effective LFV Lagrangian. We shall also argue that studies of radiative ...

#### Polarized Localization Microscopy (Plm) Detects Nanoscale Membrane Curvature And Induced Budding By Cholera Toxin Subunit B (Ctxb), Abir Kabbani

##### Wayne State University Dissertations

The curvature of biological membranes at the nanometer scale is critically important for vesicle trafficking, organelle morphology, and disease propagation. Many proteins and lipids interact with diverse curvature sensing and curvature generating mechanisms. Deciphering the molecular mechanisms of toxin-membrane interactions has been limited by the resolution and drawbacks of conventional experimental techniques. This study reveals the inherent membrane bending capability of cholera toxin subunit B (CTxB) through the development and implementation of Polarized Localization Microscopy (PLM). PLM is a pointillist optical imaging technique for the detection of nanoscale membrane curvature in correlation with single-molecule dynamics and molecular sorting.

PLM combines ...

Kilovoltage Intensity Modulated Radiotherapy, Brian Loughery Jan 2018

#### Kilovoltage Intensity Modulated Radiotherapy, Brian Loughery

##### Wayne State University Dissertations

Contrast enhanced kilovoltage radiotherapy could be a significant improvement over the standard of care in glioblastoma multiforme, but its potential benefit has been hindered by fears of insufficient dose falloff, high skin and skull dose, contrast delivery concerns, and high cost. This dissertation aims to address the validity of these fears.

Contrast delivery concerns are examined by assuming that sufficient dose can be safely delivered to the tumor. Iodine, gadolinium, and gold nanoparticle biological effect and delivery research is examined and the ideal contrast delivery methods are reported. Dose falloff and skull dose are then investigated through treatment planning and ...

Jan 2018

#### Doped And Chemically Transformed Transition Metal Dichalcogenides (Tmdcs) For Two-Dimensional (2d) Electronics, Sagar Prasad Paudel

##### Wayne State University Dissertations

Transition metal dichalcogenides (TMDCs) as the semiconductor counterparts of gra-phene have emerged as promising channel materials for flexible electronic and optoelectronic devices. The 2D layer structure of TMDCs enables the ultimate scaling of TMDC-based devices down to atomic thickness. Furthermore, the absence of dangling bonds in these materials helps to form high quality heterostructures with ultra-clean interfaces. The main objective of this work is to develop novel approaches to fabricating TMDC-based 2D electronic devices such as diodes and transistors. In the first part, we have fabricated 2D p-n junction diodes through van der Waals assembly of heavily p-doped MoS2 (WSe2 ...

Crustal Cooling In The Neutron Star Low-Mass X-Ray Binary Ks 1731−260, Rachael Lynn Merritt Jan 2017

#### Crustal Cooling In The Neutron Star Low-Mass X-Ray Binary Ks 1731−260, Rachael Lynn Merritt

##### Wayne State University Theses

Neutron stars in binary systems can undergo periods of accretion (outburst), where in- falling material heats the crust of the star out of thermal equilibrium with the core. When accretion stops (quiescence), we can directly observe the thermal relaxation of the crust. Crustal cooling of accretion-heated neutron stars provides insight into the stellar interior of neutron stars. The neutron star X-ray transient, KS 1731−260, was in outburst for 12.5 years before returning to quiescence in 2001. Here, we present a 150 ks Chandra observation of KS 1731−260 taken in August 2015, about 14.5 years into quiescence ...

#### Azimuthally-Differential Pion Femtoscopy Relative To The Second And Third Harmonic In Pb-Pb Collisions, Mohammad Saleh

##### Wayne State University Dissertations

Heavy-ion collisions at LHC energies create a hot and dense medium of deconned quarks

and gluons, known as the quark-gluon plasma (QGP) [56]. The QGP reball rst expands,

cools and then freezes out into a collection of nal-state hadrons. Correlations between the

free particles carry information about the space-time extent of the emitting source, and are

imprinted on the nal-state spectra due to a quantum-mechanical interference eect [18].

The correlation of two identical particles at small relative momentum, commonly known as

intensity, or Hanbury Brown-Twiss (HBT), interferometry, is an eective tool to study the

space-time structure of the emitting source ...

#### Quantum Capacitance Study Of Novel Two- And One-Dimensional Systems, Zhe Wu

##### Wayne State University Dissertations

Among strongly correlated systems, vanadium dioxide (VO2) shows a metal insulator transition (MIT) near room temperature (340K). Both Mott and structural transitions contribute to the MIT in VO2. To gain a better understanding of the changing electronic structure, we perform quantum capacitance measurement. Quantum capacitance measurement has already yielded insight into a variety of systems, including the negative compressibility for strongly interacting charges in GaAs two-dimensional charges. Our work demonstrates a unique method to accurately distinguish the quantum capacitance from large resistance changes at the MIT by using a home-made capacitance bridge. We observe a steep increase in the density ...

Attosecond Spectroscopy Probing Electron Correlation Dynamics, Alexander Heinecke Winney Jan 2017

#### Attosecond Spectroscopy Probing Electron Correlation Dynamics, Alexander Heinecke Winney

##### Wayne State University Dissertations

Electrons are the driving force behind every chemical reaction. The exchange, ionization, or even relaxation of electrons is behind every bond broken or formed. According to the Bohr model of the atom, it takes an electron 150 as to orbit a proton[6]. With this as a unit time scale for an electron, it is clear that a pulse duration of several femtoseconds will not be sufficient to understanding electron dynamics. Our work demonstrates both technical and scientific achievements that push the boundaries of attosecond dynamics. TDSE studies show that amplification the yield of high harmonic generation (HHG) may be ...

##### Wayne State University Dissertations

Purpose: With a fast adoption of emerging technologies, it is critical to fully test and understand its limits and capabilities. In this work we investigate new graphic processing unit (GPU) based treatment planning algorithm and its applications in helical tomotherapy dose delivery. We explore the limits of the system by applying it to challenging clinical cases of total marrow irradiation (TMI) and stereotactic radiosurgery (SRS). We also analyze the feasibility of alternative fractionation schemes for total body irradiation (TBI) and TMI based on reported historical data on lung dose and interstitial pneumonitis (IP) incidence rates.

Methods and Materials: An anthropomorphic ...

#### Nanostructured Lithium Iron Silicate/Carbon Composites As Cathode Material For Next Generation Of Lithium-Ion Batteries, Ajay Kumar

##### Wayne State University Dissertations

Lithium iron silicate (Li2FeSiO4) has the potential as cathode material for next generation lithium ion batteries because of its high specific theoretical capacity (330 mA h g-1), low cost, environmental benignity, and improved safety. However, itsintrinsically poor electronic conductivity and slow lithium ion diffusion in the solid phase limits its applications. To address these issues, we studied mesoporous Li2FeSiO4/C composites synthesized by sol-gel (SG) and solvothermal (ST) methods using tri-block copolymer (P123) as carbon source and structure directing agent. The Li2FeSiO4/C (ST) composites show improved electrochemical performance compared to Li2FeSiO4/C (SG). At C/30 rate, Li2FeSiO4/C ...

Jan 2017

#### Investigation Of The Microsoft Kinect V2 Sensor As A Multi-Purpose Device For A Radiation Oncology Clinic, Evan Asher Silverstein

##### Wayne State University Dissertations

For a radiation oncology clinic, the number of devices available to assist in the workflow for radiotherapy treatments are quite numerous. Processes such as patient verification, motion management, or respiratory motion tracking can all be improved upon by devices currently on the market. These three specific processes can directly impact patient safety and treatment efficacy and, as such, are important to track and quantify. Most products available will only provide a solution for one of these processes and may be outside the reach of a typical radiation oncology clinic due to difficult implementation and incorporation with already existing hardware. This ...

Commissioning Of The Large Angle Beamstrahlung Monitor At Superkekb, Salvatore Di Carlo Jan 2017

#### Commissioning Of The Large Angle Beamstrahlung Monitor At Superkekb, Salvatore Di Carlo

##### Wayne State University Dissertations

The Large Angle Beamstrahlung Monitor (LABM) is a device capable to monitor

the beam-beam collisions. The LABM measures the beamstrahlung light emitted

at large angle during the collisions of electron and positron beams. The properties

of the beamstrahlung, spectrum and polarization, are fundamentally related to the

size and relative position of the beams. Measuring the beamstrahlung, the LABM

delivers information about the size of the beams and their relative position at the

interaction point. The LABM will be part of the instrumentation of SuperKEKB,

a new e+e− collider that aims to reach the world record luminosity of 8×10 ...

Interaction-Driven Phenomena And Wigner Transition In Two-Dimensional Systems, Talbot Anderson Knighton Jan 2017

#### Interaction-Driven Phenomena And Wigner Transition In Two-Dimensional Systems, Talbot Anderson Knighton

##### Wayne State University Dissertations

The formation of a quantum Wigner Cyrstal (WC) is one of the most anticipated predictions of electron-electron interaction. This is expected to occur in zero magnetic field when the Coulomb energy $E_C$ dominates over the Fermi energy $E_F$ (at a ratio $r_s \equiv E_C/E_F \sim 37$) for temperatures $T \ll E_F / k_B$. The extremely low $T$ and ultra dilute carrier concentrations necessary to meet these requirements are difficult to achieve. Alternatively, a perpendicular magnetic $B$-field can be used to quench the kinetic energy. As $B$ increases, various energies compete to produce the ground state. High purity systems with ...

Monte-Carlo Event Generators For Jet Modification In D(P)-A And A-A Collisions, Michael Charles Kordell Ii Jan 2017

#### Monte-Carlo Event Generators For Jet Modification In D(P)-A And A-A Collisions, Michael Charles Kordell Ii

##### Wayne State University Dissertations

This work outlines methods to use jet simulations to study both initial and final state nuclear effects in heavy-ion collisions. To study the initial state of heavy-ion collisions, the production of jets and high momentum hadrons from jets, produced in deuteron ($d$)-$Au$ collisions at the relativistic heavy-ion collider (RHIC) and proton ($p$)-$Pb$ collisions at the large hadron collider (LHC) are studied as a function of \emph{centrality}, a measure of the impact parameter of the collision. A modified version of the event generator PYTHIA, widely used to simulate $p$-$p$ collisions, is used in conjunction with a nuclear ...

#### Topics In High-Energy Physics: The Proton Magnetic Radius And Phenomenology Of Z0 Mediation Of Supersymmetry Breaking, Joydeep Roy

##### Wayne State University Dissertations

This dissertation describes two topics in high-energy physics. In the first we describe the

extraction of the magnetic radius of the proton. In the second we impose LHC constraints on

the combined anomaly and Z’ mediation mechanisms of supersymmetry breaking.

We combine constraints from analyticity with experimental electron-proton scattering data

to determine the proton magnetic radius without model-dependent assumptions on the shape

of the form factor. We also study the impact of including electron-neutron scattering data,

and ππ ! NN¯ data. Using representative datasets we find for a cut of Q2 ≤ 0:5 GeV2,

r

pM

= 0:91+0:03

−0 ...

Jan 2017

#### Nonlinear Dynamic Studies Of Pattern-Forming And Biomedical Systems, Doaa Taha

##### Wayne State University Dissertations

Nonlinear phenomena are ubiquitous in nature and in almost every discipline of science. Various nonlinear dynamic theories are being developed to investigate a wide range of complex nonlinear systems. In this work, we study two types of nonlinear phenomena. The first type involves understanding and controlling the properties and dynamics of two-dimensional (2D) material systems. We develop a binary phase field crystal (PFC) model which simultaneously addresses diffusive dynamics of large-scale systems and resolves material microstructures, and apply the model to the study of two material systems. (1) We use this PFC model to investigate the self assembly of 2D ...

Dynamic Fluctuations From Hydrodynamics And Kinetic Theory In High Energy Collisions, Christopher David Zin Jan 2017

#### Dynamic Fluctuations From Hydrodynamics And Kinetic Theory In High Energy Collisions, Christopher David Zin

##### Wayne State University Dissertations

It is well accepted that heavy ion collisions can be described using hydrodynamic theory, implying these systems are large enough and long lived enough to reach local equilibrium. Recent measurements of correlations in pA and high multiplicity pp collisions at the Relativistic Heavy Ion Collider and Large Hadron Collider have shown that these systems also exhibit signs of thermalization, unexpected in the smaller, shorter lived systems. Studying this behavior can give insight into the thermalization process and help clarify the relationship between flow in large systems and hydrodynamics. In an effort to understand these measurements we use the Boltzmann equation ...

An Automated System To Measure The Quantum Efficiency Of Ccds For Astronomy, Rebecca Ann Coles Jan 2016

#### An Automated System To Measure The Quantum Efficiency Of Ccds For Astronomy, Rebecca Ann Coles

##### Wayne State University Dissertations

We describe a system to measure the Quantum Efficiency in the wavelength range of 300nm to 1100nm of 40x40 mm n-channel CCD sensors for the construction of the 3.2 gigapixel LSST focal plane. The technique uses a series of instruments to create a very uniform flux of photons of controllable intensity in the wavelength range of interest across the face the sensor. This allows the absolute Quantum Efficiency to be measured with an accuracy in the 1% range. This system will be part of a production facility at Brookhaven National Lab for the basic component of the LSST camera.

Multiferroicity In Iron Vanadate, Magnetite And Polyvinylidene Fluoride Nanocomposite Films, Ehab Hamdy Abdelmonaim Abdelhamid Jan 2016

#### Multiferroicity In Iron Vanadate, Magnetite And Polyvinylidene Fluoride Nanocomposite Films, Ehab Hamdy Abdelmonaim Abdelhamid

##### Wayne State University Dissertations

With the increasing demand on cheaper and better performance multifunctional materials for different applications, it is becoming more crucial to have a better understanding of the physics needed to tailor more devices and materials to fit better in every day’s technological needs. Materials which show more than one ferroic order simultaneously –namely, multiferroics– are of particular importance for their potential applications as multiple state memory elements, transducers and electrically tunable microwave devices.

In this work, we studied FeVO4 single crystals as an example on low symmetry multiferroics. We focused on the anisotropy in those crystals in an attempt to ...

Fe3o4 Nanoparticles For Magnetic Hyperthermia And Drug Delivery: Synthesis, Characterization And Cellular Studies, Maheshika Palihawadana Arachchige Jan 2016

#### Fe3o4 Nanoparticles For Magnetic Hyperthermia And Drug Delivery: Synthesis, Characterization And Cellular Studies, Maheshika Palihawadana Arachchige

##### Wayne State University Dissertations

In recent years, magnetic nanoparticles (MNPs), especially superparamagnetic Fe3O4nanoparticles, have attracted a great deal of attention because of their potential applications in biomedicine. Among the other applications, Magnetic hyperthermia (MHT), where localized heating is generated by means of relaxation processes in MNPs when subjected to a radio frequency magnetic field, has a great potential as a non-invasive cancer therapy treatment. Specific absorption rate (SAR), which measures the efficiency of heat generation, depends on magnetic properties of the particles such as saturation magnetization (Ms), magnetic anisotropy (K), particle size distribution, magnetic dipolar interactions, and the rheological properties of the target medium ...

Optimization Of Transition-Metal Dichalcogenides Based Field- Effect- Transistors Via Contact Engineering, Meeghage Madusanka Perera Jan 2016

#### Optimization Of Transition-Metal Dichalcogenides Based Field- Effect- Transistors Via Contact Engineering, Meeghage Madusanka Perera

##### Wayne State University Dissertations

ABSTRACT

Optimization of Transition-Metal Dichalcogenides based Field- Effect-Transistors via contact engineering

by

Meeghage M Perera

September , 2016

Major: Physics (Condensed mater physics/nano-electronics)

Degree: Doctor of Philosophy

Layered transition Metal Dichalcogenides (TMDs) have demonstrated a wide range of remarkable properties for applications in next generation nano-electronics. These systems have displayed many “graphene-like” properties including a relatively high carrier mobility, mechanical flexibility, chemical and thermal stability, and moreover offer the significant advantage of a substantial band gap. However, the fabrication of high performance field-effect transistors (FETs) of TMDs is challenging mainly due to the formation of a ...

Jan 2016

#### Force Field Development With Gomc A Fast New Monte Carlo Molecular Simulation Code, Jason Richard Mick

##### Wayne State University Dissertations

In this work GOMC (GPU Optimized Monte Carlo) a new fast, flexible, and free molecular Monte Carlo code for the simulation atomistic chemical systems is presented. The results of a large Lennard-Jonesium simulation in the Gibbs ensemble is presented. Force fields developed using the code are also presented. To fit the models a quantitative fitting process is outlined using a scoring function and heat maps. The presented n-6 force fields include force fields for noble gases and branched alkanes. These force fields are shown to be the most accurate LJ or n-6 force fields to date for these compounds, capable ...

Principal Component Analysis-Based Anatomical Motion Models For Use In Adaptive Radiation Therapy Of Head And Neck Cancer Patients, Mikhail Aleksandrovich Chetvertkov Jan 2016

#### Principal Component Analysis-Based Anatomical Motion Models For Use In Adaptive Radiation Therapy Of Head And Neck Cancer Patients, Mikhail Aleksandrovich Chetvertkov

##### Wayne State University Dissertations

Purpose: To develop standard and regularized principal component analysis (PCA) models of anatomical changes from daily cone beam CTs (CBCTs) of head and neck (H&N) patients, assess their potential use in adaptive radiation therapy (ART), and to extract quantitative information for treatment response assessment.

Methods: Planning CT (pCT) images of H&N patients were artificially deformed to create “digital phantom” images, which modeled systematic anatomical changes during Radiation Therapy (RT). Artificial deformations closely mirrored patients’ actual deformations, and were interpolated to generate 35 synthetic CBCTs, representing evolving anatomy over 35 fractions. Deformation vector fields (DVFs) were acquired between pCT ...

Jan 2016

#### Two-Dimensional Low-Resistance Contacts For High Performance Wse2 And Mos2 Transistors, Hsun Jen Chuang

##### Wayne State University Dissertations

ABSTRACT

TWO-DIMENSIONAL LOW-RESISTANCE CONTACTS FOR HIGH PERFORMANCE WSe2 and MoS2, TRANSISTORS

by

Hsun-jen Chuang

May 2016

Major: Physics

Degree: Doctor of Philosophy

Two-dimensional layered materials beyond graphene such as transition metal dichalcogenides (TMDs) have attracted a lot of interests due to their superior property in many aspects. In this work, I am focusing on two TMD materials: WSe2 and MoS2. The main objective this work is to develop novel approaches to fabricating low-resistance ohmic contacts to TMDs for low power, high performance electronic applications. First, we used graphene as electrical contacts for WSe2 field-effect transistor with ...

Jan 2016

#### Dielectric Anomalies Of Both Chiral And Achiral Nematogens Near The Isotropic To Mesogenic Phase Transition, Garrett Justin Godfrey

##### Wayne State University Dissertations

The dielectric properties of nematic liquid crystals were studied in both the achiral and chiral limits. For achiral nematics, the literature documents that pretransitional curvature occurs for polar molecules on both sides of the nematic and isotropic phase transition. This curvature is due to anti-parallel dimer formation. However, past models have failed to quantitatively describe pretransitional curvature. Through a generalization of the order parameter, a macroscopic model has been developed to mathematically describe the pretransitional curvature on the isotropic side of the transition. The new model was fitted to dielectric data from the literature. Meaningful parameter estimates were extracted.

The ...

#### How Geometric Distortions Scatter Electronic Excitations In Conjugated Macromolecules: Towards Photoinduced Relaxation And Energy Transfer, Tian Shi

##### Wayne State University Dissertations

The exciton scattering (ES) approach has been developed to study electronic excitations in large branched conjugated molecules. It attributes excited states to standing waves in the quasi-one-dimensional system by assuming a quasi-particle picture of optical excitations. Tight binding models extend capability of the ES approach to investigate the exciton-phonon coupling.

The topological counting method plays a substantial role in constructing tight binding models. It depicts the ES equations as a topological intersection problem. Then, by applying the index theorem, we can get the total number of excited states, which is equal to the number of repeat units plus topological charges ...

Jan 2016

#### Electronic Transport In Two-Dimensional Systems In The Quantum Hall Regime, Vinicio Tarquini

##### Wayne State University Dissertations

The integer and the fractional quantum Hall effects are essential to the exploration of quantum matters characterized by topological phases. A quantum Hall system hosts one-dimensional (1D) chiral edge channels that manifest zero magnetoresistance, dissipationless due to the broken time reversal symmetry, and quantized Hall resistance v h e^2 with v being the topological invariant (or Chern number). The 1-1 correspondence between the conducting gapless edge channels to the gapped incompressible bulk states is a defining character of a topological insulator (TI). Understanding this correspondence in real systems, especially the origin of its robustness (in terms of the limit ...