Physics Commons^™

The Grasshopper's Journey To The Bloch Sphere, David Llamas

Graduate Doctoral Dissertations

The Grasshopper Problem asks a simple geometric question. A grasshopper lands on a lawn of fixed area and jumps a fixed distance in a random direction. What shape of lawn maximizes the probability that the grasshopper remains on the lawn after jumping? The jump rule is rotationally symmetric, but the best lawns do not have to be. This dissertation studies how that symmetry breaking occurs, maps the continuum problem to a novel constrained spin system, and uses the spherical Grasshopper Problem to compare quantum singlet correlations with classical local models.

For planar lawns, boundary-integral and perturbative calculations explain why the …

A Statistical Mechanics Approach To Reinforcement Learning, Jacob Adamczyk

Graduate Doctoral Dissertations

Reinforcement learning (RL), the study of optimal decision-making over long timescales in stochastic systems, has recently seen remarkable advances due in large part to the efforts of the deep learning community. RL has witnessed great success in solving problems in video games, robotics, biological control, and language modeling. However, a unified statistical mechanics framework to understand and develop the corresponding algorithms is lacking. To address this issue, we begin by showing that the reinforcement learning problem can be formulated and solved using the tools of statistical mechanics. Drawing on physical principles of free energy minimization and invariance, we address important …

Dynamics Of Swimming Microorganisms At Structured Liquid Crystal Interfaces, Vajra Sabhapathy Badha

Graduate Doctoral Dissertations

Active matter systems are self-driven units that consume energy to generate motion and mechanical stresses, producing non-equilibrium states of broad physical significance. Examples include synthetic microswimmers and migrating cells. Motile bacteria are a widely studied biological example because their self-propelled motion, hydrodynamic interactions, and collective organization are strongly coupled to local environmental conditions. Their swimming is sensitive to interfacial viscoelasticity, ordering, confinement, and hydrodynamic boundary effects, making them useful for investigating how interfaces regulate active biological motion. Because bacterial accumulation and attachment at interfaces are central to colonization and biofilm formation, these interactions are relevant to both active matter physics …

Enhanced Osseointegration Of Functionally Graded Co˗Cr˗Mo˗Ti/Ha Implants: In Vitro And In Vivo Study In A Rabbit Model, Afrah M. Al Hussainey, Randa Kamel Hussain, Aseel Mustafa Abdul Majeed

Karbala International Journal of Modern Science

    The present investigation aims to evaluate the effects of acid and laser surface treatments on the surface characteristics, biocompatibility, and osseointegration of functionally graded implants fabricated from a Co–Cr–Mo–Ti/HA alloy. The implant surfaces were modified using either an Nd: YAG laser or hydrochloric acid (HCl), while untreated implants served as controls. Atomic force microscopy (AFM) showed that the acid-treated surface exhibited the highest mean surface roughness (Sa) of 58.10 ± 0.24 nm compared to the laser-treated surface (42.64 ± 0.83 nm) and the untreated surface (37.73 ± 0.89 nm). The MTT assay also demonstrated a favourable cellular response on the …

Toward A Post-Modern Daoist Pedagogy: Bridging Complexity And Dao Through Inner Cultivation And Autopoietic Currere, Jie Yu, Jingyu Liu

Journal of Contemplative and Holistic Education

This article first critically examines the call to reenchant the world as it resonates within a middle space between science and mysticism and then connects key ideas from complexity theory and systems thinking on complex adaptive systems with two seminal Daoist texts: the Neiye (《內業》, Inner Cultivation), a proto-Daoist chapter from the Guanzi anthology (4th–3rd century B.C.E.), and the Huangting Jing (《黃庭經》, Yellow Court Scripture), a later Daoist classic (3rd–4th century C.E.). Through this dialogue, the article advocates a post-modern Daoist pedagogy through inner cultivation and autopoietic currere—an autopoietic process wherein curriculum emerges organically through participatory dialogue …

Fabrication Of Objectives For Imaging Ultracold Lithium, Danelle Akanova

Dartmouth College Master’s Theses

This thesis develops a documented, reproducible procedure for building diffraction-limited microscope objectives entirely from catalog singlets, for imaging ultracold 6Li atoms in a ring-trap experiment. The objectives must resolve micron-scale features through a 5 mm fused-silica vacuum window, operate at multiple wavelengths, fit inside a 48 mm magnet bore, and contain no conductive or magnetic material, because the surrounding coils switch 0.1 T fields on microsecond timescales. Commercial long-working-distance objectives are universally housed in metal, which the eddy-current constraint rules out, and custom fabrication of a suitable non-conductive matched pair is estimated at nearly $200k.

The procedure is developed and …

Development Of Quantum Cryptographic Algorithm For Next Generation Secure Systems, Gururaja Ts Mr

Theses and Dissertations

The rapid advancement of digital communication and quantum technologies are developing at an accelerated pace makes cybersecurity and data protection a big challenge. The traditional cryptographic methods are increasingly under attack by phishing, brute force, cryptanalytic attack and threats of quantum computing. This research presents a quantum-secure communication based on Quantum Random Number Generator (QRNG), Quantum Key Distribution (QKD), Quantum Image Encryption (QIE) and secure quantum key access using a dongle-based hardware.

QRNG models were designed in the quantum simulator and hardware. The sequences produce high entropy and they passed the statistical randomness tests with p-values higher than 0.01 indicates …

Temperature Predictions With Zncuins/Zns Quantum Dots, Reu/Fri Program Physics And Astronomy, Amber Banks

Student Works

For hundreds of years, humans have built thermometers based on the principles of thermal expansion and contraction. In the modern world, there is a need to scale down our thermometers to monitor cellular reactions, both within the human body and within artificial organ chips. Lewis et al. (2020) introduces a nanoscale thermometer based on the thermal expansion of CdTe quantum dots. When ex panded, these dots exhibit systematic changes in photoluminescence (PL) which are recognized by a neural network as an increase in temperature. Our research builds upon the framework of Lewis et al. (2020), testing its feasibility with ZnCuInS/ZnS …

Synthesis, Thermal Stability, And Ionic Conductivity Of Phenyl-Extended Viologen Ditriflate Salts: Tailoring Properties Via Oxyethylene Chain Length, Seonghyeok L. Cox, Emily Moon, Si L. Chen, David King, Haesook Han, Pradip K. Bhowmik, Calvin Ng Yi Bin, Thamil Selvi Velayutham, Alfonso Martinez-Felipe

Chemistry and Biochemistry Faculty Research

Six new phenyl-extended viologen salts with oxyethylene groups paired with triflate anions (OTF) have been synthesized using anionic ring-opening and ring-closing reactions (ANRORC) and metathesis reactions with LiOTf salts. The salts, which contain terminal oxyethylene chains of varying lengths ((CH₂CH₂O)_n, n = 1, 2, 3, 4, 5, and 7), are named PEOn-OTF. These materials exhibit a fluorescence response and possess high thermal stability, with processing windows up to approximately 300 °C, as confirmed by thermogravimetric analysis. While samples with short chain lengths (n = 1, 2, and 3) undergo crystallization observed …

Feedback Indices To Evaluate Llm Responses To Rebuttals For Multiple Choice Type Questions, Justin C. Dunlap, Anne-Simone Parent, Ralf Widenhorn

Physics Faculty Publications and Presentations

We present a set of indices designed to characterize Large Language Model (LLM) responses when challenged with rebuttals during a chat. Assessing how LLMs respond to user dissent is crucial for understanding their reliability and behavior patterns, yet the complexity of human-LLM interactions makes systematic evaluation challenging. Our approach employs a fictitious-response rebuttal method that quantifies LLM behavior when presented with multiple-choice questions followed by deliberate challenges to their fictitious previous response. The indices are specifically designed to detect and measure what could be characterized as sycophantic behavior (excessive agreement with user challenges) or stubborn responses (rigid adherence to the …

Three-Dimensional Cell And Nuclear Geometries Inform Tissue Level Fluid Mechanics During Epithelial Remodeling, Liam Joseph Russell

Electronic Theses and Dissertations

During epithelial remodeling, mechanical and molecular programs must coordinate to drive the cell shape changes that enable new tissue topologies. Dynamic morphogenesis requires epithelia to preferentially exhibit solid- or fluidlike properties depending on developmental and biophysical constraints. Convergent extension in the Drosophila germband epithelium is one such remodeling event, during which the lateral ectoderm lengthens by two-fold along the primary body axis while concomitantly shortening orthogonally. This process is an incredibly dynamic and attractable system for studying tissue morphogenesis mechanics in vivo.

Germband extension is driven by oriented cell intercalation through T1 transitions, where cells directionally interdigitate with one another …

Field-Like- And Self-Spin-Orbit Torques In Magnetic Multilayer Films, Kyle Jeffrey Peterson

Electronic Theses and Dissertations

Spin-orbit torques (SOTs) have been realized as an energy efficient mechanism to manipulate and drive magnetization dynamics in magnetic multilayer films. Their damping-like and field-like components provide distinct pathways for controlling the magnetization, enabling switching, sustaining magneto-oscillations, and driving domain-wall motion with potential applications in nonvolatile memory, spin-based logic, and microwave signal generation. However, the accurate quantification and interpretation of these torques remains complicated by experimental sensitivity, the co-symmetry of the Oersted field and the effective field due to the field-like torque, and assumptions regarding the material layers from which the torques originate. The body of work set forth in …

Exploring Red Palm Oil As A Sustainable Plasticizer For Carbon Black-Filled Ssbr/Br Tire Tread Compounds: A Comparative Evaluation Of Commercial Alternatives, Norma Arisanti Kinasih, Mohamad Irfan Fathurrohman, Santi Puspitasari, Dewi Kusuma Arti, Abdulhakim Masa

Journal of Materials Exploration and Findings

This study investigates the application of red palm oil (RPO) as an alternative vegetable oil resource to substitute petroleum-based plasticizers, which have environmental and health concerns, in carbon black (CB)-filled SSBR/BR tire tread compounds. The plasticizing effects of RPO were thoroughly evaluated by comparing them with a commercial bio-based plasticizer, Epoxidized Soybean Oil (ESBO), and two safer petroleum-based oils, Naphthenic Oil (NYNAS) and Treated Distillate Aromatic Extract (TDAE). The initial investigation shows that fatty acid composition is imposing regarding the plasticizing effect. The higher unsaturated fatty acid content in RPO than in ESBO improved tensile strength and degraded rolling resistance …

Metallurgical Investigation Of A Modified Eye Bolt Failure Caused By Improper Weld Extension, Specification Deviation, And Crevice Corrosion, Dimas Muhammad Fawwaz, Reza Miftahul Ulum, Johny Wahyuadi Soedarsono, Yudha Pratesa

Journal of Materials Exploration and Findings

A modified eye bolt from the David Arm Manhole Storage Tank underwent thorough metallurgical study due to the consequences of the bolt's malfunction during operation. Safety issues arose when the manhole door detached during operation. The mechanical testing and chemical composition analysis of the bolts indicated they were manufactured from an ASTM A193 Grade B7 material used for high-temperature bolting. This material did not conform to the engineering drawing, which mentioned SA 563A, which is about nuts, not bolts. This contradiction clearly shows that the eye bolt which was installed does not conform to the intended design. Welded connections of …

Rejection Of Fe (Iron) And Kmno4 (Organic Substance) Parameters In Peat Water Using Organic Membranes, Muhamad Rafli Sakti Mulia Gonera, Siti Umi Kalsum, Sarah Fiebrina Heraningsih

Journal of Materials Exploration and Findings

Peat water is a surface water source widely used by people in swampy and lowland areas, but it has poor quality characteristics such as high organic matter content, low pH, and dissolved metal levels such as iron that exceed the threshold. These conditions can cause health problems and reduce the quality of clean water so that effective treatment technology is needed. This study aims to analyze the effectiveness of ultrafiltration membranes made from chitosan from shrimp shell waste in rejecting iron (Fe) and organic substances in peat water, and to determine the effect of pressure on separation performance. This study …

Developing Field And Spaceflight Microscopy, Nikki Johnston

Dissertations and Theses

Designing for spaceflight favors the reduction of unnecessary features and cost-cutting, whether thisbe computation, hardware, or procedure. Resources are spent toward fortification and mission success over convenience. Such design goals paired with the relatively smaller budgets of academia lead us to do as much as we can in-house and use open-source as much as we can without compromising mission success. We also believe that thoroughly testing technology in extreme environments on earth is necessary for the success of a flight instrument. We focus on microscopy for life detection. I have spent my time here learning methods of hand-building microscopes to …

Website: Home, Zhiqu Lu, Likun Zhang, Lei Cao

Gulf Research Program Data Sets

No abstract provided.

Website: Latest Results, Zhiqu Lu, Likun Zhang, Lei Cao

Gulf Research Program Data Sets

No abstract provided.

Website: News And Events, Zhiqu Lu, Likun Zhang, Lei Cao

Gulf Research Program Data Sets

No abstract provided.

Evaluating A Dual-Beacon Hartmann Turbulence Profiling Technique Using Wave Optics Simulations, Benjamin C. Wilson, Matthew Kalensky, Santasri Bose-Pillai, Jack E. Mccrae

Faculty Publications

Resolving how optical turbulence varies along a propagation path remains a key challenge for designers of free-space optical propagation systems. Instruments such as scintillometers and differential image motion monitors are commonly used, but only provide path-integrated turbulence estimates. Point sensors provide localized estimates of turbulence strength and can be used to generate path-resolved profiles when an array of point sensors are distributed along the optical path. However, this approach can be costly and complex to deploy in certain environments. Alternatively, a single point sensor can be mounted on a mobile platform that collects data while traversing the optical path, although …