Physical Sciences and Mathematics Commons^™

Relating Dust Reference Models To Conventional Systems In Manifestly Gauge Invariant Perturbation Theory, Kristina Giesel, Bao-Fei Li, Parampreet Singh

Faculty Publications

Models with dust reference fields in relational formalism have proved useful in understanding the construction of gauge invariant perturbation theory to arbitrary orders in the canonical framework. These reference fields modify the dynamical equations for perturbation equations. However, important questions remain open on the relation with conventional perturbation theories of inflaton coupled to gravity and of multifluid systems, and on understanding modifications in terms of physical degrees of freedom. These gaps are filled in this manuscript for Brown-Kuchar and Gaussian dust models, both of which involve three scalar physical degrees of freedom. We establish a relationship of these models with …

Octo-Tiger: A New, 3d Hydrodynamic Code For Stellar Mergers That Uses Hpx Parallelization, Dominic C. Marcello, Sagiv Shiber, Orsola De Marco, Juhan Frank, Geoffrey C. Clayton, Patrick M. Motl, Patrick Diehl, Hartmut Kaiser

Faculty Publications

OCTO-TIGER is an astrophysics code to simulate the evolution of self-gravitating and rotating systems of arbitrary geometry based on the fast multipole method, using adaptive mesh refinement. OCTO-TIGER is currently optimized to simulate the merger of well-resolved stars that can be approximated by barotropic structures, such as white dwarfs (WDs) or main-sequence stars. The gravity solver conserves angular momentum to machine precision, thanks to a 'correction' algorithm. This code uses firx parallelization, allowing the overlap of work and communication and leading to excellent scaling properties, allowing for the computation of large problems in reasonable wall-clock times. In this paper, we …

Simulation Of Compound Flood Events In Low-Gradient Coastal Watershed, Felix Luis Santiago-Collazo

LSU Doctoral Dissertations

Low-gradient coastal watersheds are susceptible to flooding caused by various flows such as rainfall, tides, and storm surge. Compound flooding occurs when at least two of these mechanisms happen simultaneously or in close succession. Different inundation models, observed data, and/or a combination of these are coupled through varying techniques involving one-way, loosely, tightly, or fully coupled approaches to assess compound flooding. This study presents a one-dimensional (1-D), fully coupled compound inundation model based on the Shallow Water equations. This model approach simultaneously simulates the free water surface variations in the ocean domain (i.e., tide and storm surge modeling), rainfall-runoff in …

Investigation On The Structure And Dynamics Of Lithium Ion Solvation Shell By Linear And Non-Linear Infrared Spectroscopy, Xiaobing Chen

LSU Doctoral Dissertations

Lithium ion battery (LIB) is a lightweight, rechargeable and powerful battery that is used widely from mobile phones to laptops to electric cars. It has many exceptional advantages such as high energy density, high output power, relatively low self-discharge, etc. However, it has some disadvantages such as safety issues, capacity loss, and expensive manufacture. LIB is composed of three main components: electrolytes, positive and negative electrodes. Researchers have been working on improving the performance of LIB for the past decade, but only a few have focused on investigating the electrolytes at the molecular level. In addition, the molecular mechanisms behind …

Berry-Esseen Bounds For Approximate Maximum Likelihood Estimators In The Α-Brownian Bridge, Khalifa Es-Sebaiy, Jabrane Moustaaid, Idir Ouassou

Journal of Stochastic Analysis

No abstract provided.

Characterizing And Optimizing Asynchronous Event-Driven Architecture For Modern Cloud Systems, Shungeng Zhang

LSU Doctoral Dissertations

Achieving good performance and high efficiency simultaneously is an essential requirement for emerging modern cloud systems such as e-commerce due to their business impact. For example, Akamai reported that every 100ms delay in website load time could lead to a 6% drop in sales. Unfortunately, achieving good performance (e.g., low latency) for modern cloud systems at high resource utilization is significantly challenging. Despite continuing efforts by cloud professionals, however, they have consistently experienced performance degradation problems (e.g., the long-tail latency problem) due to the bursty workload in the cloud. To resolve the performance degradation problems, many previous research efforts have …

Numeric And Dynamic B-Stability, Exact-Monotone And Asymptotic Two-Point Behavior Of Theta Methods For Stochastic Differential Equations, Henri Schurz

Journal of Stochastic Analysis

No abstract provided.

A Generalized, Modular Approach To Treating Moving Tumors With Ion Beams, Michelle Jennifer Lis

LSU Doctoral Dissertations

Despite advancements in cancer therapy, certain indications continue to have a poor prognosis, including cancers of the thorax. Existing methods for treating moving tumors with carbon ions have shown promise, but require technologically complex facilities and still have inherent limitations to mitigating tumor motion. The goal of this dissertation was to develop and test a safe, portable, and modular motion-synchronized dose delivery system (M-DDS) and its peripheral components as a framework for studying motion mitigation with ion beams.

We designed and integrated a motion-synchronized radiotherapy approach, called multi-phase 4D delivery (MP4D), as modular units of a clinical dose delivery system. …

Loop Quantum Black Hole Extensions Within The Improved Dynamics, Rodolfo Gambini, Javier Olmedo, Jorge Pullin

Faculty Publications

We continue our investigation of an improved quantization scheme for spherically symmetric loop quantum gravity. We find that in the region where the black hole singularity appears in the classical theory, the quantum theory contains semi-classical states that approximate general relativity coupled to an effective anisotropic fluid. The singularity is eliminated and the space-time can be continued into a white hole space-time. This is similar to previously considered scenarios based on a loop quantum gravity quantization.

Mapping Plastic Pollution In The Amite Watershed, Louisiana, Gourav Divan

LSU Master's Theses

Microplastics have quickly emerged as a concerning pollutant in both freshwater and marine environments. Their recent discovery means that their impacts are still being studied, however, it is important to continuously monitor their concentrations. An important conduit of plastic pollution to marine environments are rivers and streams. Previous models have estimated the transport of plastics from land to sea in many parts of the world. Most of these models, however, have been conducted at coarse spatial resolutions that make it difficult to establish tractable management programs to minimize this impact. Here, a previously existing model was applied to model for …

An Equivalence Between Contact Gluing Maps In Sutured Floer Homology: A Conjecture Of Zarev, Charles Ryan Leigon

LSU Doctoral Dissertations

We show that the contact gluing map of Honda, Kazez, and Matic has a natural algebraic description in bordered sutured Floer homology. In particular, we establish Zarev's conjecture that his gluing map on sutured Floer homology is equivalent, in the appropriate sense, to the contact gluing map. This further solidifies the relationship between bordered Floer theory and contact geometry.

On Distributions Of Self-Adjoint Extensions Of Symmetric Operators, Franco Fagnola, Zheng Li

Journal of Stochastic Analysis

No abstract provided.

Sphincs_Bssn: A General Relativistic Smooth Particle Hydrodynamics Code For Dynamical Spacetimes, S. Rosswog, P. Diener

Faculty Publications

We present a new methodology for simulating self-gravitating general-relativistic fluids. In our approach the fluid is modelled by means of Lagrangian particles in the framework of a general-relativistic (GR) smoothed particle hydrodynamics (SPH) formulation, while the spacetime is evolved on a mesh according to the Baumgarte-Shapiro-Shibata-Nakamura (BSSN) formulation that is also frequently used in Eulerian GR-hydrodynamics. To the best of our knowledge this is the first Lagrangian fully general relativistic hydrodynamics code (all previous SPH approaches used approximations to GR-gravity). A core ingredient of our particle-mesh approach is the coupling between the gas (represented by particles) and the spacetime (represented …

Noncommutative Tensor Triangular Geometry And Its Applications To Representation Theory, Kent Barton Vashaw

LSU Doctoral Dissertations

One of the cornerstones of the representation theory of Hopf algebras and finite tensor categories is the theory of support varieties. Balmer introduced tensor triangular geometry for symmetric monoidal triangulated categories, which united various support variety theories coming from disparate areas such as homotopy theory, algebraic geometry, and representation theory. In this thesis a noncommutative version will be introduced and developed. We show that this noncommutative analogue of Balmer's theory can be determined in many concrete situations via the theory of abstract support data, and can be used to classify thick tensor ideals. We prove an analogue of prime ideal …

Wildfires: Vegetation Recovery And The Potential For Future Fires, Moses Okonkwo

LSU Master's Theses

Analysis of satellite imagery combined with Geographic Information Systems (GIS), often allows for observing the increasing changes in land cover dynamics. These changes are often on a macro scale buoyed by natural hazards such as wildfires. This study examines the vegetation recovery dynamics by using multispectral data and also gleaned insight in the applications of Hyperspectral satellite imagery in the study of vegetation dynamics. Both Landsat 8 Operational Land Imager (OLI) (multispectral) and the Earth-Observing One (EO-1) (hyperspectral) data are freely available; however the former has a limited spatial and temporal coverage. The relationship between vegetation recovery, elevation, aspect and …

Anticipating Linear Stochastic Differential Equations With Adapted Coefficients, Hui-Hsiung Kuo, Pujan Shrestha, Sudip Sinha

Journal of Stochastic Analysis

No abstract provided.

On Properties Of Weil Sums Of Binomials, Liem P. Nguyen

LSU Doctoral Dissertations

This dissertation explores questions regarding the Weil sum of binomials, a finite field character sum originated from information theory. The Weil spectrum counts distinct values of the Weil sum through invertible elements in the finite field. The value of these sums and the size of the Weil spectrum are of particular interest, as they link problems in information theory, coding theory, and cryptography to other areas of math such as number theory and arithmetic geometry. In the setting of Niho exponents, we prove the Vanishing Conjecture of Helleseth ($1971$) on the presence of zero values in the Weil spectrum and …

Ecosytem Services: Delivering Decision-Making For Salt Marshes, Philine S. E. Zu Ermgassen, Ronald Baker, Michael W. Beck, Kate Dodds, Sophus O. S. E. Zu Ermgassen, Debbrota Mallick, Matthew D. Taylor, R. Eugene Turner

Faculty Publications

No abstract provided.

Applications Of Nonstandard Analysis In Probability And Measure Theory, Irfan Alam

LSU Doctoral Dissertations

This dissertation broadly deals with two areas of probability theory and investigates how methods from nonstandard analysis may provide new perspectives in these topics. In particular, we use nonstandard analysis to prove new results in the topics of limiting spherical integrals and of exchangeability.

In the former area, our methods allow us to represent finite dimensional Gaussian measures in terms of marginals of measures on hyperfinite-dimensional spheres in a certain strong sense, thus generalizing some previously known results on Gaussian Radon transforms as limits of spherical integrals. This first area has roots in the kinetic theory of gases, which is …

Validation Of A Respiratory Gating System For Automated Delivery Of The Deep Inspiration Breath-Hold Technique, Michael G. Stock

LSU Master's Theses

Purpose: To validate the performance of a respiratory gating system for the automated delivery of the deep inspiration breath-hold (DIBH) technique.

Methods: The gating system utilized an automatic gating interface (Elekta Response) which connected a marker-based respiratory motion monitoring system to the linear accelerator control system. The gating system was characterized dosimetrically and temporally using two distinct approaches. Central-axis output and energy constancy were evaluated across 8 beam-matched linear accelerators. Additionally, a representative set of 5 treatment plans were delivered both non-gated and gated to a 2D diode array (MapCHECK). The respiratory motion monitoring system optically tracked a reflective marker …

Characterizing The Northern Hemisphere Circumpolar Vortex Through Space And Time, Nazla Bushra

LSU Doctoral Dissertations

This hemispheric-scale, steering atmospheric circulation represented by the circumpolar vortices (CPVs) are the middle- and upper-tropospheric wind belts circumnavigating the poles. Variability in the CPV area, shape, and position are important topics in geoenvironmental sciences because of the many links to environmental features. However, a means of characterizing the CPV has remained elusive. The goal of this research is to (i) identify the Northern Hemisphere CPV (NHCPV) and its morphometric characteristics, (ii) understand the daily characteristics of NHCPV area and circularity over time, (iii) identify and analyze spatiotemporal variability in the NHCPV’s centroid, and (iv) analyze how CPV features relate …

Methodology Utilizing Triphosgene To Promote Cyclization Of Epoxy Ketones To Pyranoside Derivatives Via Proposed Epoxonium Ions, Isaac Camargo Dos Reis

LSU Master's Theses

The development of new methodologies in organic chemistry is of great importance. In fact, the discovery and creation of new reactions frequently uncovers new chemical reactivities and creates new areas of chemistry. The purpose of this thesis is to present the development of new synthetic reactions that were discovered through previous findings. Additionally, the main theme of this work relies on the intermediacy of a cationic reactive intermediate: epoxonium ions. Chapter 1 provides a brief review of bicyclic epoxonium ions and methods for their generation, as well as their utility in the synthesis of interesting heterocycles. Furthermore, Chapter 1 illustrates …

Incorporating Life Into Living Shorelines: Can Gulf Ribbed Mussels Reduce Shoreline Erosion And Enhance Restoration Practices?, Jordan Logarbo

LSU Master's Theses

The gulf ribbed mussel (Geukensia granosissima) exists throughout the Gulf of Mexico and influences biotic and abiotic environmental attributes as an ecosystem engineer. Ribbed mussels are an important component of marsh ecosystems providing services including filtering particulate matter, depositing and transforming nutrients in the system, increasing soil strength via byssal threads and providing structure via their shells.

The spatial distribution of mussels along the marsh edge of Sister Lake, LA was investigated via a broad survey of 150 sites, in relation to elevation, exposure and vegetation percent cover. This survey was followed by a second survey at a …

Hydrometeorological Responses To Abrupt Land Surface Change Following Hurricane Michael, Shannon Alexis Nelson

LSU Master's Theses

While many of the destructive environmental conditions associated with tropical cyclones are well recognized, tropical cyclone-induced defoliation, a reduction in green leaves and mature vegetation, has been largely overlooked as a source of environmental stress following tropical cyclone passage. The land surface change associated with defoliation reduces evapotranspiration and shade, thus altering boundary layer moisture and energy fluxes that drive the local water cycle, for many months after tropical cyclone passage. Understanding the potential for any hydrometeorological impacts arising from such abrupt land surface change is important for guiding future post-hurricane preparedness and recovery planning in coastal communities.

This thesis …

The Edwards Model For Fractional Brownian Loops And Starbursts, Wolfgang Bock, Torben Fattler, Ludwig Streit

Journal of Stochastic Analysis

No abstract provided.

Machine Learning Methods For Depression Detection Using Smri And Rs-Fmri Images, Marzieh Sadat Mousavian

LSU Doctoral Dissertations

Major Depression Disorder (MDD) is a common disease throughout the world that negatively influences people’s lives. Early diagnosis of MDD is beneficial, so detecting practical biomarkers would aid clinicians in the diagnosis of MDD. Having an automated method to find biomarkers for MDD is helpful even though it is difficult. The main aim of this research is to generate a method for detecting discriminative features for MDD diagnosis based on Magnetic Resonance Imaging (MRI) data.

In this research, representational similarity analysis provides a framework to compare distributed patterns and obtain the similarity/dissimilarity of brain regions. Regions are obtained by either …

Quantifying Feature Overlaps In Deep Neural Networks And Their Applications In Unsupervised Learning And Generative Adversarial Networks, Edward Collier

LSU Doctoral Dissertations

Deep neural network learn a wide range of features from the input data. These features take many different forms from, structural to textural, and can be very scale invariant. The complexity of these features also differs from layer to layer. Much like the human brain, this behavior in deep neural networks can also be used to cluster and separate classes. Applicability in deep neural networks is the quantitative measurement of the networks ability to differentiate between clusters in feature space. Applicability can measure the differentiation between clusters of sets of classes, single classes, or even within the same class. In …

Musical Gesture Through The Human Computer Interface: An Investigation Using Information Theory, Michael Vincent Blandino

LSU Doctoral Dissertations

This study applies information theory to investigate human ability to communicate using continuous control sensors with a particular focus on informing the design of digital musical instruments. There is an active practice of building and evaluating such instruments, for instance, in the New Interfaces for Musical Expression (NIME) conference community. The fidelity of the instruments can depend on the included sensors, and although much anecdotal evidence and craft experience informs the use of these sensors, relatively little is known about the ability of humans to control them accurately. This dissertation addresses this issue and related concerns, including continuous control performance …

Mosquito Distribution And Stoichiometric Analysis Between Open And Closed Canopies In New Orleans Cemeteries, Rachel Rogers

LSU Master's Theses

Cemetery vases represent an important container habitat for mosquito larvae. Some species, like, Aedes albopictus and Aedes aegypti, prefer container habitats, whereas others, like Culex quinquefasciatus, will opportunistically use containers. In New Orleans, these three medically important vector species (Ae. albopictus Ae. aegypti, and Cx. quinquefasciatus) co-occur, despite a demonstrated competitive advantage of Ae. albopictus to the other two. Here we test the hypothesis that canopy cover from trees could be a mediating factor in driving mosquito assemblages in New Orleans, by influencing food sources, and the microclimate experienced by mosquito larvae. Samples from seven …

Modeled Changes In Source Contributions Of Particulate Matter During The Covid-19 Pandemic In The Yangtze River Delta, China, Jinlong Ma, Juanyong Shen, Peng Wang, Shengqiang Zhu, Yu Wang, Pengfei Wang, Gehui Wang, Jianmin Chen, Hongliang Zhang

Faculty Publications

Within a short time after the outbreak of coronavirus disease 2019 (COVID-19) in Wuhan, Hubei, the Chinese government introduced a nationwide lockdown to prevent the spread of the pandemic. The quarantine measures have significantly decreased the anthropogenic activities, thus improving air quality. To study the impacts caused by the lockdown on specific source sectors and regions in the Yangtze River Delta (YRD), the Community Multiscale Air Quality (CMAQ) model was used to investigate the changes in source contributions to fine particulate matter (PM2.5) from 23 January to 28 February 2020, based on different emission control cases. Compared to case 1 …