Physical Sciences and Mathematics Commons^™

Tunable Linear And Nonlinear Metasurfaces Based On Hybrid Gold-Graphene Plasmons, Matthew Feinstein

Dissertations, Theses, and Capstone Projects

Optical Metasurfaces are planar structures that are patterned with subwavelength structures and are very thin compared to the wavelength of light. Despite their thinness, these structured materials can strongly interact with incident light to effect the functionalities of conventional optical components, such as rotation of the polarization state, beam steering, lensing, spectral filtering, and holography, to name a few. Metasurfaces can also facilitate nonlinear optical effects, such as the mixing of beams at different frequencies to generate a beam at a new frequency.

The ability to alter the behavior of a metasurface during operation is highly desired for applications such …

Temperature Evolution Of Domains And Intradomain Chirality In 1t- Tas2, Boning Yu, Ghilles Ainouche, Manoj Singh, Bishnu Sharma, James Huber, Michael Boyer

Physics

We use scanning tunneling microscopy to study the temperature evolution of the atomic-scale properties of the nearly commensurate charge density wave (NC-CDW) state of the low-dimensional material 1T-TaS2. Our measurements at 203, 300, and 354 K, roughly spanning the temperature range of the NC-CDW state, show that while the average CDW periodicity is temperature independent, domaining and the local evolution of the CDW lattice within a domain are temperature dependent. Further, we characterize the temperature evolution of the displacement field associated with the recently discovered intradomain chirality of the NC-CDW state by calculating the local rotation vector. Intradomain chirality throughout …

Cluster Scaling And Critical Points: A Cautionary Tale, W. Klein, Harvey Gould, Sakib Matin

Physics

Many systems in nature are conjectured to exist at a critical point, including the brain and earthquake faults. The primary reason for this conjecture is that the distribution of clusters (avalanches of firing neurons in the brain or regions of slip in earthquake faults) can be described by a power law. Because there are other mechanisms such as 1/f noise that can produce power laws, other criteria that the cluster critical exponents must satisfy can be used to conclude whether or not the observed power-law behavior indicates an underlying critical point rather than an alternate mechanism. We show how a …

Dynamics Of Magnetoelastic Robots In Water-Saturated Granular Beds, Animesh Biswas, Trinh Huynh, Balaram Desai, Max Moss, Arshad Kudrolli

Physics

We investigate the dynamics of a magnetoelastic robot with a dipolar magnetic head and a slender elastic body as it performs undulatory strokes and burrows through water-saturated granular beds. The robot is actuated by an oscillating magnetic field and moves forward when the stroke amplitude increases above a critical threshold. By visualizing the medium, we show that the undulating body fluidizes the bed, resulting in the appearance of a dynamic burrow, which rapidly closes in behind the moving robot as the medium loses energy. We investigate the applicability of Lighthill's elongated body theory of fish locomotion, and estimate the contribution …

Molecular Mechanisms Of Amyloid-Like Fibril Formation, Sharareh Jalali

Dissertations

Proteins play a critical role in living systems by performing most of the functions inside cells. The latter is determined by the protein's three-dimensional structure when it is folded in its native state. However, under pathological conditions, proteins can misfold and aggregate, accounting for the formation of highly ordered insoluble assemblies known as amyloid fibrils. These assemblies are associated with diseases like Parkinson's and Alzheimer's. Strong evidence suggests that three mechanisms are critical for forming amyloid fibrils. These mechanisms are the nucleation of amyloid fibrils in solution (primary nucleation) as well as on the surface of existing fibrils (secondary nucleation) …

Exploring Topological Phonons In Different Length Scales: Microtubules And Acoustic Metamaterials, Ssu-Ying Chen

Dissertations

The topological concepts of electronic states have been extended to phononic systems, leading to the prediction of topological phonons in a variety of materials. These phonons play a crucial role in determining material properties such as thermal conductivity, thermoelectricity, superconductivity, and specific heat. The objective of this dissertation is to investigate the role of topological phonons at different length scales.

Firstly, the acoustic resonator properties of tubulin proteins, which form microtubules, will be explored The microtubule has been proposed as an analog of a topological phononic insulator due to its unique properties. One key characteristic of topological materials is the …

Bacterial Motion And Spread In Porous Environments, Yasser Almoteri

Dissertations

Micro-swimmers are ubiquitous in nature from soil and water to mammalian bodies and even many technological processes. Common known examples are microbes such as bacteria, micro-algae and micro-plankton, cells such as spermatozoa and organisms such as nematodes. These swimmers live and have evolved in multiplex environments and complex flows in the presence of other swimmers and types, inert particles and fibers, interfaces and non-trivial confinements and more. Understanding the locomotion and interactions of these individual micro-swimmers in such impure viscous fluids is crucial to understanding the emergent dynamics of such complex systems, and to further enabling us to control and …

Fluid Dynamics Of Interacting Particles: Bouncing Droplets And Colloid-Polymer Mixtures, Lauren Barnes

Dissertations

Interacting particles are a common theme across various physical systems, particularly on the atomic and sub-atomic scales. While these particles cannot be seen with the human eye, insight into such systems can be gained by observing macroscopic systems whose physical behavior is similar. This dissertation consists of three different chapters, each presenting a different problem related to interacting particles, as follows:

Chapter 1 explores chaotic trajectories of a droplet bouncing on the surface of a vertically vibrating fluid bath, with a simple harmonic force acting on the droplet. The bouncing droplet system has attracted recent interest because it exhibits behaviors …

Boundary Integral Equation Methods For Superhydrophobic Flow And Integrated Photonics, Kosuke Sugita

Dissertations

This dissertation presents fast integral equation methods (FIEMs) for solving two important problems encountered in practical engineering applications.

The first problem involves the mixed boundary value problem in two-dimensional Stokes flow, which appears commonly in computational fluid mechanics. This problem is particularly relevant to the design of microfluidic devices, especially those involving superhydrophobic (SH) flows over surfaces made of composite solid materials with alternating solid portions, grooves, or air pockets, leading to enhanced slip.

The second problem addresses waveguide devices in two dimensions, governed by the Helmholtz equation with Dirichlet conditions imposed on the boundary. This problem serves as a …

Variable Resolution Smoothed Particle Hydrodynamics Schemes For 2-D And 3-D Viscous Flows, Francesco Ricci

Dissertations

Smoothed Particle Hydrodynamics (SPH) is a Lagrangian particle-based method for the numerical solution of the partial differential equations that govern the motion of fluids. The main aim of this thesis work is to better enable the applicability of SPH to problems involving multi-scale fluid dynamics. In the first part of the thesis, the capability of the SPH method to simulate three-dimensional isotropic turbulence is investigated with a detailed comparison of Lagrangian and Eulerian SPH formulations. The main reason for this first investigation is to provide an assessment of the error introduced by the particle disorder on the SPH discrete operators …

Feasibility Of Functional Mri On Point-Of-Care Mr Platforms, Arjama Halder

Electronic Thesis and Dissertation Repository

Magnetic resonance imaging (MRI) has proven to be a clinically valuable tool that can produce anatomical and functional images with improved soft tissue contrast compared to other imaging modalities. There has recently been a surge in low- and mid-field scanners due to hardware developments and innovative acquisition techniques. These compact scanners are accessible, offer reduced siting requirements and can be made operational at a reduced cost.

This thesis aims to implement blood-oxygen-level-dependent (BOLD) resting-state functional MRI (fMRI) at such a mid-field point-of-care scanner. The availability of this technique can be beneficial to get neurological information in cases of traumatic brain …

Supporting Neurodivergent Talent: Adhd, Autism, And Dyslexia In Physics And Space Sciences, Niescja E. Turner, Heather Haynes Smith

Physics and Astronomy Faculty Research

Diversity, equity, inclusion, and belonging efforts must include disability and neurodivergence. While there is a long history of famous scientists being identified or speculatively indicated to be neurodivergent, identification on an individual basis has been limited until fairly recently. Definitions have changed and broadened, and people are being identified or are identifying themselves as neurodivergent and are learning about their paths and their brains in a way that was unavailable to people two decades ago. In the contemporary physics or space science classroom or workplace, we have both a responsibility to include and support our neurodivergent learners and scientists, as …

The Importance Of Recruitment And Retention In Heliophysics: It's Not Just A Pipeline Problem, A. J. Halford, C. M. Bard, A. G. Burrell, R. M. Mcgranaghan, L. B. Wilson Iii, M. Jones Jr, C. Dong, L. Wang, T. I. Pulkkinen, Niescja E. Turner, M. W. Liemohn, J. Klenzing

Physics and Astronomy Faculty Research

A major obstacle in cultivating a robust Heliophysics (and broader scientific) community is the lack of diversity throughout science, technology, engineering, and mathematics (STEM) fields. For many years, this has been understood as a “leaky pipeline” analogy, in which predominately minority students initially interested in STEM gradually fall (or are pushed) out of the field on their way to a scientific research position. However, this ignores critical structural and policy issues which drive even later career Ph.D.s out of a career in Heliophysics. We identify here several systemic problems that inhibit many from participating fully in the Heliophysics community, including …

An Improved Source Of Spin-Polarized Electrons Based On Spin Exchange In Optically Pumped Rubidium Vapor, K. J. Ahrendsen, Kenneth Wayne Trantham, D. Tupa, T. J. Gay

Department of Physics and Astronomy: Faculty Publications

We have improved a polarized electron source in which unpolarized electrons undergo collisions with a mixture of buffer gas molecules and optically spin-polarized Rb atoms. With a nitrogen buffer gas, the source reliably provides spin polarization between 15% and 25% with beam currents >4 μA. Vacuum pump upgrades mitigate problems caused by denatured diffusion pump oil, leading to longer run times. A new differential pumping scheme allows the use of higher buffer gas pressures up to 800 mTorr. With a new optics layout, the Rb polarization is continuously monitored by a probe laser and improved pump laser power provides more …

Search For Magnetoelectric Monopole Response In Cr2O3 Powder, Syed Qamar Abbas Shah, Ather Mahmood, Arun Parthasarathy, Christian H. Binek

Department of Physics and Astronomy: Faculty Publications

Powder samples have been suggested as a pathway to fabricate isotropic magnetoelectric (ME) materials which effectively only have a pseudoscalar or monopole ME response. We demonstrate that random distribution of ME grains alone does not warrant isotropic ME response because the activation of a nonvanishing ME response requires a ME field cooling protocol which tends to induce preferred axes.We investigate the evolution of ME susceptibility in powder chromia samples for various ME field cooling protocols both theoretically and experimentally. In particular, we work out the theoretical expressions for ME susceptibility for powder chromia in the framework of statistical mechanics where …

Development And Benchmark Of A 1d3v Electrostatic Pic/Mcc Numerical Code For Gas Discharge Simulations, İbrahi̇m Arda, İsmai̇l Rafatov

Turkish Journal of Physics

Gas discharge plasmas are low-temperature nonequilibrium plasmas that have a wide range of scientific and technological applications. The particle-in-cell/Monte Carlo collision (PIC/MCC) method is a reliable approach for numerical analyses and simulations of such plasmas. In this study, we first provide a detailed description of the basics of this method. We then verify the programme code that we developed in Fortran by benchmarking the code against a widely referred reference study simulating a radiofrequency capacitively coupled plasma (RFCCP) in helium for various discharge conditions. We show that the results of the present study are in good agreement with that of …

A Compendious Review Of Majorization-Based Resource Theories: Quantum Information And Quantum Thermodynamics, Gökhan Torun, Onur Pusuluk, Özgür Esat Müstecaplioğlu

Turkish Journal of Physics

The field of quantum resource theory (QRT) has emerged as an invaluable framework for the examination of small and strongly correlated quantum systems, surpassing the boundaries imposed by traditional statistical treatments. The fundamental objective of general QRTs is to characterize these systems by precisely quantifying the level of control attainable to an experimenter. In this review article, we refrain from providing an exhaustive summary of the extensive literature on QRT. Rather, our focus centers on a specific subliterature founded upon the theory of majorization. The primary aim is to augment our comprehension of genuine quantum phenomena manifested across diverse technological …

Hellings And Downs Correlation Of An Arbitrary Set Of Pulsars, Bruce Allen, Joseph D. Romano

Physics and Astronomy Faculty Publications and Presentations

Pulsar timing arrays (PTAs) detect gravitational waves (GWs) via the correlations they induce in the arrival times of pulses from different pulsars. We assume that the GWs are described by a Gaussian ensemble, which models the confusion noise produced by expected PTA sources. The mean correlation h2μu(γ) as a function of the angle γ between the directions to two pulsars was predicted by Hellings and Downs in 1983. The variance σ2tot(γ) in this correlation was recently calculated [B. Allen, Variance of the Hellings-Downs correlation, Phys. Rev. D 107, 043018 (2023)] for a single noise-free pulsar pair at angle γ, …

Hellings And Downs Correlation Of An Arbitrary Set Of Pulsars, Bruce Allen, Joseph D. Romano

Physics and Astronomy Faculty Publications and Presentations

Pulsar timing arrays (PTAs) detect gravitational waves (GWs) via the correlations they induce in the arrival times of pulses from different pulsars. We assume that the GWs are described by a Gaussian ensemble, which models the confusion noise produced by expected PTA sources. The mean correlation h2μu(γ) as a function of the angle γ between the directions to two pulsars was predicted by Hellings and Downs in 1983. The variance σ2tot(γ) in this correlation was recently calculated [B. Allen, Variance of the Hellings-Downs correlation, Phys. Rev. D 107, 043018 (2023)] for a single noise-free pulsar pair at angle γ, …

A Sensitivity Study Of Triboson Production Processes To Dimension-6 Eft Operators At The Lhc, R. Bellan, S. Bhattacharya, G. Boldrini, F. Cetorelli, P. Govoni, A. Massironi, A. Mecca, C. Tarricone, A. Vagnerini

Department of Physics and Astronomy: Faculty Publications

We present the first parton-level study of anomalous effects in triboson production in both fully and semi-leptonic channels in proton-proton collisions at 13TeV at the Large Hadron Collider (LHC). The sensitivity to anomalies induced by a minimal set of bosonic dimension-6 operators from the Warsaw basis is evaluated with specific analyses for each final state. A likelihood-based strategy is employed to assess the most sensitive kinematic observables per channel, where the contribution of Effective Field Theory operators is parameterized at either the linear or quadratic level. The impact of the mutual interference terms of pairs of operators on the sensitivity …

A Search For Decays Of The Higgs Boson To Invisible Particles In Events With A Top-Antitop Quark Pair Or A Vector Boson In Proton-Proton Collisions At √S = 13 Tev, Armen R. Tumasyan

Department of Physics and Astronomy: Faculty Publications

The first search for nonresonant production of Higgs boson pairs (HH) with one H decaying into four leptons and the other into a pair of b quarks is presented, using proton-proton collisions recorded at a center-of-mass energy of √s = 13 TeV by the CMS experiment. The analyzed data correspond to an integrated luminosity of 138 fb⁻¹. A 95% confidence level upper limit of 32.4 is set on the signal strength modifier μ, defined as the ratio of the observed HH production rate in the HH → ZZ*bb → 4ℓbb decay channel to the standard model …

Finite Charges From The Bulk Action, Robert Mcnees, Céline Zwikel

Physics: Faculty Publications and Other Works

Constructing charges in the covariant phase space formalism often leads to formally divergent expressions, even when the fields satisfy physically acceptable fall-off conditions. These expressions can be rendered finite by corner ambiguities in the definition of the presymplectic potential, which in some cases may be motivated by arguments involving boundary Lagrangians. We show that the necessary corner terms are already present in the variation of the bulk action and can be extracted in a straightforward way. Once these corner terms are included in the presymplectic potential, charges derived from an associated codimension-2 form are automatically finite. We illustrate the procedure …

Online Data Transmission Reduction Scheme For Energy Conservation In Wireless Video Sensor Networks, Iman Kadhum Abbood, Ali Kadhum Idrees

Karbala International Journal of Modern Science

Wireless Video Sensor Networks (WVSNs) are networks of low-cost, low-power camera sensor nodes. These nodes communicate locally and process information to meet an application's goal. WVSNs are extensively used in diverse monitoring applications, such as security, military, industrial, medical, and environmental monitoring. However, the transmission of large amounts of data collected by video sensor nodes in WVSNs poses challenges in terms of energy consumption, bandwidth usage, and network congestion. Reducing energy for processing and transmitting data in WVSNs is difficult due to the huge amount of sensed data in real-time. To address this issue, this paper proposes an Online Data …

Biogenesis Synthesis Of Zno Nps: Its Adsorption And Photocatalytic Activity For Removal Of Acid Black 210 Dye, Zahraa A. Najm, Mohammed A. Atiya, Ahmed K. Hassan

Karbala International Journal of Modern Science

This study investigated the treatment of textile wastewater contaminated with Acid Black 210 dye (AB210) using zinc oxide nanoparticles (ZnO NPs) through adsorption and photocatalytic techniques. ZnO NPs were synthesized using a green synthesis process involving eucalyptus leaves as reducing and capping agents. The synthesized ZnO NPs were characterized using UV-Vis spectroscopy, SEM, EDAX, XRD, BET, Zeta potential, and FTIR techniques. The BET analysis revealed a specific surface area and total pore volume of 26.318 m²/g. SEM images confirmed the crystalline and spherical nature of the particles, with a particle size of 73.4 nm. A photoreactor was designed …

Initial Experience With An Electron Flash Research Extension (Flex) For The Clinac System, Kyuhak Oh, Kyle J. Gallagher, Megan Hyun, Diane Schott, Sarah Wisnoskie, Yu Lei, Samuel Hendley, Jeffrey Wong, Shuo Wang, Brendan Graff, Christopher Jenkins, Frank Rutar, Md Ahmed, Joshua Mcneur, Jeffrey Taylor, Marty Schmidt, Lasitha Senadheera, Wendy Smith, Subodh M. Lele, Ran Dai, Dong Jianghu (James), Y Yan, Su-Min Zhou

Department of Physics and Astronomy: Faculty Publications

Purpose: Radiotherapy delivered at ultra-high-dose-rates (≥40 Gy/s), that is, FLASH, has the potential to effectively widen the therapeutic window and considerably improve the care of cancer patients. The underlying mechanism of the FLASH effect is not well understood, and commercial systems capable of delivering such dose rates are scarce. The purpose of this study was to perform the initial acceptance and commissioning tests of an electron FLASH research product for preclinical studies.

Methods: A linear accelerator (Clinac 23EX) was modified to include a nonclinical FLASH research extension (the Clinac-FLEX system) by Varian, a Siemens Healthineers company (Palo Alto, …

Syllabus For Computational Physics (Phys 39907), Mark D. Shattuck

Open Educational Resources

Syllabus for City College of New York Computational Physics course.

Ultrasound Assisted Comparative Study Of Fucolam And So-Dium Alginate And Impact On Their Physiochemical Proper-Ties Using Box-Behnken Design, Uday Bagale, Ammar Kadi, Artem Malinin, Varisha Anjum, Irina Potoroko

Karbala International Journal of Modern Science

The article discusses about the possibility of comparing the impact of ultrasonic treatment on fucolam and sodium algi-nate. The purpose was to study the effect of micronization on the sulfated heteropolysaccharide fucolam, analyzing its dispersed state and accessibility by reducing its molecular weight and increasing antioxidant activity. The optimization of the micronization process was carried out using the Box-Behnken Design (BBD) method, with a sonication time ranging from 15 to 45 min, power ranging from 50 to 100 W/cm2, and temperature between 30 °C and 40 °C. The fixed lower fucolam concentration was 0.1%. The results illustrated that sonochemical treatment …

Deep Learning-Based Cad System For Predicting The Covid-19 X-Ray Images, Aqeel R. Talib, Hana’ M. Ali

Karbala International Journal of Modern Science

According to World Health Organization data, Coronavirus (COVID-19) has infected about 660, 378, 145 patients around the world. It is nonetheless difficult for physicians to detect COVID-19 infections out of CT or X-ray radiographs. Thus, several computer-aided diagnosis (CAD) systems based on deep learning and radiographs were developed to detect COVID-19 infections. However, the majority of approaches considered small datasets, which is ineligible to provide diverse COVID-19 radiographs. This work utilizes a massive number of X-ray radiographs, and compared standard CNN, DenseNet-121, and GoogLeNet for isolating COVID-19 infections out from normal and other pneumonia radiographs. The dataset in this work …

Investigation Of Student Understanding Of Representations Of Probability Concepts In Quantum Mechanics, William D. Riihiluoma

Electronic Theses and Dissertations

The ability to relate physical concepts and phenomena to multiple mathematical representations—and to move fluidly between these representations—is a critical outcome expected of physics instruction. In upper-division quantum mechanics, students must work with multiple symbolic notations, including some that they have not previously encountered. Thus, developing the ability to generate and translate expressions in these notations is of great importance, and the extent to which students can relate these expressions to physical quantities and phenomena is crucial to understand.

To investigate student understanding of the expressions used in these notations and the ways they relate, clinical think-aloud interviews were conducted …

Multi-Agent Deep Reinforcement Learning For Radiation Localization, Benjamin Scott Totten

Dissertations and Theses

For the safety of both equipment and human life, it is important to identify the location of orphaned radioactive material as quickly and accurately as possible. There are many factors that make radiation localization a challenging task, such as low gamma radiation signal strength and the need to search in unknown environments without prior information. The inverse-square relationship between the intensity of radiation and the source location, the probabilistic nature of nuclear decay and gamma ray detection, and the pervasive presence of naturally occurring environmental radiation complicates localization tasks. The presence of obstructions in complex environments can further attenuate the …