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Characterization Of Boreal-Arctic Vegetation Growth Phases And Active Soil Layer Dynamics In The High-Latitudes Of North America: A Study Combining Multi-Year In Situ And Satellite-Based Observations, Michael G. Brown

Dissertations, Theses, and Capstone Projects

This dissertation examined the seasonal freeze/thaw activity in boreal-Arctic soils and vegetation physiology in Alaska, USA and Alberta, Canada, using in situ environmental measurements and passive microwave satellite observations. The boreal-Arctic high-latitudes have been experiencing ecosystem changes more rapidly in comparison to the rest of Earth due to the presently warming climatic conditions having a magnified effect over Polar Regions. Currently, the boreal-Arctic is a carbon sink; however, recent studies indicate a shift over the next century to become a carbon source. High-latitude vegetation and cold soil dynamics are influenced by climatic shifts and are largely responsible for the regions …

Can The Mdcdw Condensate Withstand The Heat Of A Cold Neutron Star?, William Gyory

Physics & Astronomy Faculty Publications

The correct description of strongly interacting matter at low temperatures and moderately high densities—in particular the conditions realized inside neutron stars—is still unknown. We review some recent results on the magnetic dual chiral density wave (MDCDW) phase, a candidate phase of quark matter for this region of the QCD phase diagram. We highlight the effects of magnetic fields and temperature on the condensate, which can be explored using a high-order Ginzburg-Landau (GL) expansion. We also explain how the condensate's nontrivial topology, which arises due to the asymmetry in the lowest Landau level modes, affects its physical properties. Finally, we comment …

Importance Of Vegetation In Tsunami Mitigation: Evidence From Large Eddy Simulations With Fluid-Structure Interactions, Abhishek Mukherjee

Dissertations

Communities worldwide are increasingly interested in nature-based solutions like coastal forests for the mitigation of coastal risks. Still, it remains unclear how much protective benefit vegetation provides, particularly in the limit of highly energetic flows after tsunami impact. The present thesis, using a three-dimensional incompressible computational fluid dynamics model with a fluid-structure interaction approach, aims to quantify how energy reflection and dissipation vary with different degrees of rigidity and vegetation density of a coastal forest.

In this study, tree trunks are represented as cylinders, and the elastic modulus of hardwood trees such as pine or oak is used to characterize …

Large-Scale And Meso-Scale Ion Dynamics Of The Near-Earth Space Environment, Matthew Cooper

Dissertations

The mechanisms whereby low energy (order of lOs to 100s of eV) solar wind and ionosphere sourced particles are accelerated to high energy (order of 10s to 100s keV) in the Earth's magnetosphere are a trending research topic due to impacts on radiation belt populations, coupling to the high-latitude ionosphere, and energy budgets for collision-less plasma in dipole fields. Ultra-low frequency (ULF, order of 1-100 mHz) Alfven waves observed in the nightside inner magnetosphere during geomagnetic activity are one such acceleration mechanism. Several source processes for these waves, including the micro-scale drift-mirror mode, have been previously suggested but observational evidence …

Topics On Asymmetric Classification, Subhrasish Chakraborty

Dissertations

Asymmetric classification refers to a situation where the cost of misclassifying one class is significantly higher than the cost of misclassifying the other class. This problem is common in many real-world scenarios, such as medical diagnosis or fraud detection. In this dissertation two of the common types of asymmetric classification problems have been dealt with — imbalanced classification and ordinal classification. An example of imbalanced classification is to detect fraudulent credit card transactions where the distribution of the normal and fraud transactions are extremely skewed. On the other hand, ordinal classification, also known as ordinal regression, is widely used in …

Molecular Simulations Of Mechanical Effects Of Adsorption In Gas And Liquid Phases, Alina Emelianova

Dissertations

Fluids adsorbing in nanoporous solids cause high pressures that affect the solids and the properties of the fluids themselves. This work explores the mechanical response of solids to the adsorption of gas and liquid. Chapter 1 outlines the current achievements in investigating the mechanical response of adsorbents to the adsorption process, specifically, the computational approaches to predict adsorption-induced deformation. Chapter 2 introduces the theoretical and computational methods employed in this work. Chapters 3-7 address the design and application of the computational techniques for such prediction in different systems: mesoporous silica, microporous zeolites, and metal-organic frameworks, and Chapter 8 focuses on …

Search For Heavy Resonances And Quantum Black Holes In Eμ, Eτ, And Μτ Final States In Proton-Proton Collisions At √S = 13 Tev, A. Tumasyan

Department of Physics and Astronomy: Faculty Publications

A search is reported for heavy resonances and quantum black holes decaying into eμ, eτ, and μτ final states in proton-proton collision data recorded by the CMS experiment at the CERN LHC during 2016–2018 at √s = 13TeV, corresponding to an integrated luminosity of 138 fb⁻¹. The eμ, eτ, and μτ invariant mass spectra are reconstructed, and no evidence is found for physics beyond the standard model. Upper limits are set at 95% confidence level on the product of the cross section and branching fraction for lepton flavor violating signals. Three benchmark signals are studied: resonant τ sneutrino …

Vibrational, Rotational And Electronic Spectroscopy For Possible Interstellar Detection Of Alnh2 And Halnh, Tarek Trabelsi, Vincent J. Esposito, Joseph S. Francisco

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

We obtained accurate vibrational frequencies, rotational constants, and vertical transition energy for AlNH₂(X¹A₁) and HAlNH(X¹A′) isomers using ab initio calculations at various levels of theory. These two isomers are potential candidates for astronomical observation. AlNH₂ and HAlNH are thermodynamically stable, with Al-NH₂ and HAl-NH bond dissociation energies predicted to be 4.39 and 3.60 eV, respectively. The two isomers are characterized by sizable dipole moments of 1.211 and 3.64 D, respectively. The anharmonic frequencies and spectroscopic constants reported for the two isomers should facilitate their experimental differentiation. In addition, we evaluated …

Symmetry Control Of Unconventional Spin–Orbit Torques In Iro2, Michael Patton, Gautam Gurung, Ding-Fu Shao, Gahee Noh, Joseph A. Mittelstaedt, Marcel Mazur, Jong-Woo Kim, Philip J. Ryan, Evgeny Y. Tsymbal, Si-Young Choi, Daniel C. Ralph, Mark S. Rzchowski, Tianxiang Nan, Chang-Beom Eom

Department of Physics and Astronomy: Faculty Publications

Spin–orbit torques generated by a spin current are key to magnetic switching in spintronic applications. The polarization of the spin current dictates the direction of switching required for energy-efficient devices. Conventionally, the polarizations of these spin currents are restricted to be along a certain direction due to the symmetry of the material allowing only for efficient in-plane magnetic switching. Unconventional spin–orbit torques arising from novel spin current polarizations, however, have the potential to switch other magnetization orientations such as perpendicular magnetic anisotropy, which is desired for higher density spintronic-based memory devices. Here, it is demonstrated that low crystalline symmetry is …

Filaments And Their Application To Air Lasing, Spectroscopy, And Guided Discharge, Ali Rastegari

Optical Science and Engineering ETDs

Laser filamentation is a fascinating phenomenon that occurs when an intense laser beam travels through transparent materials, in particular air. At sufficiently high power (TW in the near IR, GW in the UV), instead of spreading out like a regular laser beam, something remarkable happens: the laser beam becomes tightly focused, creating a thin and intense column of light called a laser filament. Laser filamentation is characterized by two main properties: (I) a high-intensity core that remains narrow over long distances beyond the Rayleigh range and (II) a low-density plasma channel within the core. In recent years, laser filamentation has …

Experiments And Data Analysis For Modulated Phase Gratings In X-Rays, Sydney B. Carr

LSU Master's Theses

Purpose: Modulated Phase Grating (MPG) interferometry has been shown in theory and simulations to produce observable fringes on a clinical detector without requiring fluence absorbing analyzer. In this work, we will experimentally show that the MPG X-ray system produces observable fringes and multi-modal X-ray images.

Motivation:Nearly 1 in 8 women in the US will develop invasive breast cancer in their lifetime, accounting for approximately 40,000 deaths each year [1-2]. In order to pursue the best treatment option available, cancer itself must be adequately imaged and staged, based on size and level of metastasis, on the order of Stage I-IV. …

Human And Technical Factors In The Adoption Of Quantum Cryptographic Algorithms, Alyssa Pinkston

Mathematical Sciences Technical Reports (MSTR)

The purpose of this research is to understand what factors would cause users to choose quantum key distribution (QKD) over other methods of cryptography. An Advanced Encryption Standard (AES) key can be exchanged through communication using the Rivest, Shamir, Adleman (RSA) cryptographic algorithm, QKD, or post-quantum cryptography (PQC). QKD relies on quantum physics where RSA and PQC use complex mathematics to encrypt data. The BB84 quantum cryptographic protocol involves communication over a quantum channel and a public channel. The quantum channel can be technically attacked by beamsplitting or intercept/resend. QKD, like other forms of cryptography, is vulnerable to social attacks …

Néel Spin Currents In Antiferromagnets, Ding-Fu Shao, Yuan-Yuan Jiang, Jun Ding, Shu-Hui Zhang, Zi-An Wang, Rui-Chun Xiao, Gautam Gurung, W. J. Lu, Y. P. Sun, Evgeny Y. Tsymbal

Department of Physics and Astronomy: Faculty Publications

Ferromagnets are known to support spin-polarized currents that control various spin-dependent transport phenomena useful for spintronics. On the contrary, fully compensated antiferromagnets are expected to support only globally spin-neutral currents. Here, we demonstrate that these globally spin-neutral currents can represent the Néel spin currents, i.e., staggered spin currents flowing through different magnetic sublattices. The Néel spin currents emerge in antiferromagnets with strong intrasublattice coupling (hopping) and drive the spin-dependent transport phenomena such as tunneling magnetoresistance (TMR) and spin-transfer torque (STT) in antiferromagnetic tunnel junctions (AFMTJs). Using RuO₂ and Fe₄GeTe₂ as representative antiferromagnets, we predict that the …

Reconstruction Of Volumetric Modulated Arc Therapy-Computed Tomography, Chia-Lung Chien

LSU Doctoral Dissertations

Purpose: Volumetric modulated arc therapy-computed tomography (VMAT-CT) was proposed in 2010 as the CBCT reconstruction technique using portal images collected during VMAT. Yet, its clinical applications were impeded by the poor image quality due to motion blurs from fast movements of multi-leaf collimator (MLC) and projection data deficiency due to truncations from MLC. The goal of this study is to develop systematic preprocessing methods, and a novel iterative reconstruction algorithm to generate quality VMAT-CT and lower the number of failure cases of VMAT-CT reconstruction.

Methods: Systematic image preprocessing methods, including Online region-based active contouring (ORACM), MLC motion modeling and outlier …

Multimessenger Observations Of Double Neutron Stars In The Galactic Disk With Gravitational And Radio Waves, Wen-Fan Feng, Jie-Wen Chen, Yan Wang, Soumya D. Mohanty, Yong Shao

Physics & Astronomy Faculty Publications

We evaluate the prospects for radio follow-up of the double neutron stars (DNSs) in the Galactic disk that could be detected through future space-borne gravitational wave (GW) detectors. We first simulate the DNS population in the Galactic disk that is accessible to space-borne GW detectors according to the merger rate from recent LIGO results. Using the inspiraling waveform for the eccentric binary, the average number of the DNSs detectable by TianQin (TQ), LISA, and TQ+LISA are 217, 368, and 429, respectively. For the joint GW detection of TQ+LISA, the forecasted parameter estimation accuracies, based on the Fisher information matrix, for …

Photoisomerizable Membrane Active Peptides, Cristina Ventura

Seton Hall University Dissertations and Theses (ETDs)

Membrane active peptides (MAPs) bind and partition into the cell membrane thus causing permeabilization. Many α-helical membrane active peptides contain central proline residues that distinguish the hydrophobic and hydrophilic faces of the helix. The proline induces a bend that produces a helix-hinge-helix motif. Mutation of these proline residues has a significant effect on the activity of the MAP. Azobenzene is a photoisomerizable molecule that switches from its trans to cis isomer upon excitation with ultraviolet (UV) light and from its cis to trans isomer upon excitation with visible light (VL). In this work it is hypothesized that the hinge function …

Maximum Likelihood Estimation Of Glandular Fraction For Mammography, Bryce Smith

LSU Master's Theses

Breast tissue is a mixture of adipose and fibro glandular tissue with a glandular fraction on average of 20%-30%. Previous studies have confirmed that there is a risk of undetected breast cancer related to the amount of glandular tissue present in the breast. Since a higher glandular fraction can lead to an increased cancer risk, it is important for radiologists to know quantitative glandular fraction when diagnosing a patient. Another increasingly popular protocol for mammography is to eliminate the anti-scatter grid and use software algorithms to reduce scatter. This work focuses on using a maximum likelihood algorithm to estimate the …

Rehybridization Dynamics Into The Pericyclic Minimum Of An Electrocyclic Reaction Imaged In Real-Time, Y. Liu, D. M. Sanchez, M. R. Ware, E. G. Champenois, J. Yang, J. P. F. Nunes, A. Attar, Martin Centurion, J. P. Cryan, R. Forbes, K. Hegazy, M. C. Hoffmann, F. Ji, M.-F. Lin, D. Luo, S. K. Saha, X. Shen, X. J. Wang, T. J. Martínez, T. J. A. Wolf

Department of Physics and Astronomy: Faculty Publications

Electrocyclic reactions are characterized by the concerted formation and cleavage of both σ and π bonds through a cyclic structure. This structure is known as a pericyclic transition state for thermal reactions and a pericyclic minimum in the excited state for photochemical reactions. However, the structure of the pericyclic geometry has yet to be observed experimentally.We use a combination of ultrafast electron diffraction and excited state wavepacket simulations to image structural dynamics through the pericyclic minimum of a photochemical electrocyclic ring-opening reaction in the molecule α-terpinene. The structural motion into the pericyclic minimum is dominated by rehybridization of two carbon …

Measurement Of The Β-Decay Properties Of A=105 Isotopes Using The Modular Total Absorption Spectrometer And The Development Of The Beta Spectrum Module, Thomas J. Ruland

LSU Doctoral Dissertations

Nuclear reactors produce an extremely diverse population of beta-decaying isotopes. Accurate and precise knowledge of the beta-decay properties of these isotopes is vital to safe reactor operations as well as informing next-generation reactor design. These beta-decay properties not only impact the design and operation of nuclear reactors, but they influence the expected antineutrino flux and spectrum measured from nuclear reactors. Historical measurements of many of these isotopes are subject to a systematic bias referred to as the Pandemonium Effect, because the low-efficiency, high-precision detectors used to perform the measurements results in misinterpreting weak gamma cascades from high- energy levels as …

Cms Pythia 8 Colour Reconnection Tunes Based On Underlying-Event Data, A. Tumasyan

Department of Physics and Astronomy: Faculty Publications

New sets of parameter tunes for two of the colour reconnection models, quantum chromodynamics-inspired and gluon-move, implemented in the pythia 8 event generator, are obtained based on the default CMS pythia 8 underlying-event tune, CP5. Measurements sensitive to the underlying event performed by the CMS experiment at centre-of-mass energies √ s = 7 and 13 TeV, and by the CDF experiment at 1.96 TeV are used to constrain the parameters of colour reconnection models and multiple-parton interactions simultaneously. The new colour reconnection tunes are compared with various measurements at 1.96, 7, 8, and 13 TeV including measurements of the underlying-event, …

Studying Quantum Memory Effects Of The Environment With Superconducting Circuits, Daria Kowsari

Arts & Sciences Graduate Student Theses and Dissertations

The presence of the environment in real-world experiments which strive to harness quantum mechanical effects is inevitable. This results in dissipation, which is known to be the main source of errors that prevent us from building a practical quantum computer. Nevertheless, one can employ the environment as a resource, especially when there is a strong coupling between the system and its environment. In this regime, the dynamics of the system is governed by the generalized Nakajima-Zwanzig master equation incorporating all the memory effects induced by the environment. The existence of memory allows us to investigate intriguing phenomena, such as the …

Unraveling The Quantum Hall Effects: From Conformal Field Theory Inspired Tensor Networks To Interacting Many-Body Simulations, Matheus Schossler

Arts & Sciences Graduate Student Theses and Dissertations

Systems confined in the two-dimensional world have long played a major role in physics. Under a quantizing magnetic field, these systems can exhibit phases of matter described by beautiful trial wave functions. Although there are numerous solvable models for fractional quantum Hall (FQH) physics, they are primarily developed and studied from the viewpoint of clustering properties of these wave functions in first quantization. Here we investigate frustration-free Hamiltonians of FQH states and their connection with 1D tensor networks, or matrix product state (MPS), based on the conformal field theory (CFT) representation of their ground and excited states. Examining these Hamiltonians …

A Torsion Balance Search For Long-Range Interactions Coupling To Baryons And Leptons And Cosmic Ray Transport For Spatially And Temporally Continuous And Discrete Sources, Dawson Huth

Arts & Sciences Graduate Student Theses and Dissertations

Part I: The expectation of new physics motivates more stringent tests of our current best understanding of gravitation, General Relativity (GR). Many theories proposing new physics predict the violation of Einstein’s equivalence principle, a set of criteria which must hold for GR to be valid. A torsion balance instrument was designed and operated to detect any violation of the equivalence principle. The motivations for performing such an experi- ment, instrument design, operational principles, data collected and subsequent analysis are described in detail in this thesis. After 51 days of continuous data collection experimental upper bounds on the violation of the …

Spectro-Polarimetric And Time Domain Characteristics Of Dynamically Evolving Accretion Flows From The General Relativistic Raytracing Of General Relativistic Magneto-Hydrodynamical Simulations, Andrew West

Arts & Sciences Graduate Student Theses and Dissertations

Black holes are among the most exotic phenomena in our universe, physical objects so dense and compact that within their horizon not even light can escape. In binary systems, black holes can accrete material from their companion star, forming an accretion disk that is subjected to extreme physical conditions. Often, these disks are accompanied by jets - highly relativistic outflows of material moving at significant fractions of the speed of light. This extreme environment is the source of some of the most luminous and energetic processes in our universe. Black hole accretion disks are often modeled as a steady state, …

Abundances Of Ultra-Heavy Cosmic Ray Nuclei With Calet, Wolfgang Vaughn Zober

Arts & Sciences Graduate Student Theses and Dissertations

This work describes the determination of the relative abundances of the Galactic Cosmic-Ray (GCR) nuclei from Z=9 through Z=40, with preliminary measurements up to Z=44, using the Calorimetric Electron Telescope (CALET) on board the International Space Station (ISS). This analysis will compare results with the top-of-atmosphere abundances from the balloon-borne SuperTIGER and top-of-instrument abundances from the space missions, ACE-CRIS and HEAO-3. This analysis also provides insight into the potential opportunities and challenges for a future SuperTIGER-like mission on the ISS.Our analysis looks at work on two separate but complementary aspects of the Ultra-Heavy (UH) analysis in CALET. CALET has a …

A Framework For Investigating Random Ensembles Of Structured Ecosystems And Quantifying Their Emergent Coarse-Grainability, Jacob Moran

Arts & Sciences Graduate Student Theses and Dissertations

The interface between statistical physics and theoretical ecology has a long history, employing powerful concepts such as ensemble approaches and typicality to study emergent properties of ecosystems. This of course raises the question of what ensembles are useful to describe the typical behaviors of evolution and ecology, but so far, the traditional context of high-diversity ecology has considered ensembles of random, unstructured ecosystems. Although much insight has been gained in this regime, one naturally wonders how representative are random ensembles of real, natural ecosystems that are arguably atypical and highly structured by evolution. Moreover, the question of coarse-graining ecosystems has …

A Stochastic Search For Intermittent Gravitational-Wave Backgrounds, Jessica Lawrence, Kevin Turbang, Andrew Matas, Arianna I. Renzini, Nick Van Remortel, Joseph D. Romano

Physics & Astronomy Faculty Publications

A likely source of a gravitational-wave background (GWB) in the frequency band of the Advanced LIGO, Virgo, and KAGRA detectors is the superposition of signals from the population of unresolvable stellar-mass binary-black-hole (BBH) mergers throughout the Universe. Since the duration of a BBH merger in band (similar to 1 s) is much shorter than the expected separation between neighboring mergers (similar to 103 s), the observed signal will be "popcornlike" or intermittent with duty cycles of order 10-3. However, the standard cross-correlation search for stochastic GWBs currently performed by the LIGO-Virgo-KAGRA Collaboration is based on a continuous-Gaussian signal model, which …

Rigorous Analysis Of Markov Processes With Applications To Quantum Information, Samuel Edwin Slezak

Physics & Astronomy ETDs

We present a rigorous analysis of the rapid convergence of techniques based on Markov chains for the simulation of thermal quantum systems. We show that a classical computing algorithm called path integral Monte Carlo is capable of simulating thermal states of transverse field Ising models above a threshold temperature by demonstrating the existence of a rapidly mixing Markov chain. We then turn to quantum computing algorithms and show that an idealized version of quantum Metropolis sampling can efficiently simulate systems that satisfy the eigenstate thermalization hypothesis. In a related result, we find a class of stoquastic frustration free Hamiltonians that …

Photonic Sensors Based On Integrated Ring Resonators, Jaime Da Silva

Mechanical Engineering Research Theses and Dissertations

This thesis investigates the application of integrated ring resonators to different sensing applications. The sensors proposed here rely on the principle of optical whispering gallery mode (WGM) resonance shifts of the resonators. Three distinct sensing applications are investigated to demonstrate the concept: a photonic seismometer, an evanescent field sensor, and a zero-drift Doppler velocimeter. These concepts can be helpful in developing lightweight, compact, and highly sensitive sensors. Successful implementation of these sensors could potentially address sensing requirements for both space and Earth-bound applications. The feasibility of this class of sensors is assessed for seismic, proximity, and vibrational measurements.

Pairing And Rotation-Induced Nuclear Exotica In Covariant Density Functional Theory, Saja Teeti

Theses and Dissertations

Covariant density functional theory (CDFT) is one of the modern theoretical tools for describing the nuclear structure physics of finite nuclei. Its performance is defined by underlying covariant energy density functionals (CEDFs). In this dissertation and within the framework of the CDFT, different physical properties of the ground and the excited states of rotating and non-rotating nuclei have been investigated.

A systematic global investigation of pairing properties based on all available experimental data on pairing indicators has been performed for the first time in the framework of covariant density functional theory. It is based on separable pairing interaction of Ref.\ …