Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

2017

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 12451 - 12480 of 12529

Full-Text Articles in Physical Sciences and Mathematics

Numerical Study Of The Periodic Anderson Model With Holstein Phonons For The Description Of Cerium Volume Collapse, Enzhi Li Jan 2017

Numerical Study Of The Periodic Anderson Model With Holstein Phonons For The Description Of Cerium Volume Collapse, Enzhi Li

LSU Doctoral Dissertations

The volume collapse transition of Cerium has intrigued physicists since its discovery several decades ago. Various models and mechanisms have been proposed, the most prominent scenarios are based on the Mott transition and the Kondo volume collapse transition. In this study, we explore the volume collapse by a dynamical mean field theory (DMFT) study of the periodic Anderson model with electron-phonon coupling to the conduction band. This allows us to study the effect of the electron-phonon interaction on the volume collapse. In order to faithfully account for the volume collapse, we also include the effects due to the volume and …

Go to article

Extraction Of Displacement Fields In Heterogeneous Media Using Optimal Local Basis Functions, Paul Derek Sinz Jan 2017

Extraction Of Displacement Fields In Heterogeneous Media Using Optimal Local Basis Functions, Paul Derek Sinz

LSU Doctoral Dissertations

The Multiscale Spectral Generalized Finite Element Method (MS-GFEM) was developed in recent work by Babuska and Lipton. The method uses optimal local shape functions, optimal in the sense of the Kolmogorov n-width, to approximate solutions to a second order linear elliptic partial differential equation with L-infinity coefficients. In this dissertation an implementation of MS-GFEM over a two subdomain partition of unity is outlined and several numerical experiments are presented. The method is applied to compute local fields inside high contrast particle suspensions. The method's performance is evaluated for various examples with different contrasts between reinforcement particles and matrix material. The …

Go to article

Branch And Stem Growth As Affected By Loss Of Leaf Area On Selected Branches In Loblolly Pine, Shannon Dumo Kidombo Jan 2017

Branch And Stem Growth As Affected By Loss Of Leaf Area On Selected Branches In Loblolly Pine, Shannon Dumo Kidombo

LSU Doctoral Dissertations

Leaf area and crown dynamics control how trees grow through their supply of carbohydrates and growth regulators, and their influence on tree mechanical stability. The influence of leaf area and crown dynamics to tree growth was investigated by testing the interdependence between leaf area, branch, and stem growth on young loblolly pine trees. The objectives were to (1) determine the influence of current and previous year’s leaf area on elongation of branches; (2) describe and test a unique way of quantitatively measuring the effect of neighbor branches on net growth of a target branch; (3) quantify the growth impact of …

Go to article

On Braids, Branched Covers And Transverse Invariants, Jose Hector Ceniceros Jan 2017

On Braids, Branched Covers And Transverse Invariants, Jose Hector Ceniceros

LSU Doctoral Dissertations

In this work, we present a brief survey of knot theory supported by contact 3-manifolds. We focus on transverse knots and explore different ways of studying transverse knots. We define a new family of transverse invariants, this is accomplished by considering $n$-fold cyclic branched covers branched along a transverse knot and we then extend the definition of the BRAID invariant $t$ defined in cite{BVV} to the lift of the transverse knot. We call the new invariant the lift of the BRAID invariant and denote it by $t_n$. We then go on to show that $t_n$ satisfies a comultiplication formula and …

Go to article

Decentralized Scheduling For Many-Task Applications In The Hybrid Cloud, Brian Lyle Peterson Jan 2017

Decentralized Scheduling For Many-Task Applications In The Hybrid Cloud, Brian Lyle Peterson

LSU Doctoral Dissertations

While Cloud Computing has transformed how we solve many computing tasks, some scientific and many-task applications are not efficiently executed on cloud resources. Decentralized scheduling, as studied in grid computing, can provide a scalable system to organize cloud resources and schedule a variety of work. By measuring simulations of two algorithms, the fully decentralized Organic Grid, and the partially decentralized Air Traffic Controller from IBM, we establish that decentralization is a workable approach, and that there are bottlenecks that can impact partially centralized algorithms. Through measurements in the cloud, we verify that our simulation approach is sound, and assess the …

Go to article

Improved Protein Characterizations Using Ionic Liquids: Page And Maldi-Ms, Punprabhashi Vidanapathirana Jan 2017

Improved Protein Characterizations Using Ionic Liquids: Page And Maldi-Ms, Punprabhashi Vidanapathirana

LSU Doctoral Dissertations

Protein separation by polyacrylamide gel electrophoresis (PAGE) and identification by matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS) are primary tools of protein analysis. In these techniques, surfactants are used in protein sample preparation in order to enhance the protein solubility. Conventional surfactants have shown limitations in protein analysis due to the structural complexity of proteomes, resulting in low resolution. The research goal of this dissertation is to address some of these limitations by applying novel cationic ionic liquid surfactants (ILS), N-alkyl-4-methyl pyridinium bromide (CnPBr where n=4, 8, 11). The ILS would be suitable candidates to be used in PAGE protein …

Go to article

Manifestations Of Symmetry In Polynomial Link Invariants, Kyle Istvan Jan 2017

Manifestations Of Symmetry In Polynomial Link Invariants, Kyle Istvan

LSU Doctoral Dissertations

The use and detection of symmetry is ubiquitous throughout modern mathematics. In the realm of low-dimensional topology, symmetry plays an increasingly significant role due to the fact that many of the modern invariants being developed are computationally expensive to calculate. If information is known about the symmetries of a link, this can be incorporated to greatly reduce the computation time. This manuscript will consider graphical techniques that are amenable to such methods. First, we discuss an obstruction to links being periodic, developed jointly with Dr. Khaled Qazaqzeh at Kuwait University, using a model developed by Caprau and Tipton. We will …

Go to article

Sediment Transport And Channel Morphology Dynamics Of Highly Regulated Alluvial Rivers - A Case Study Of The Lowermost Mississippi River., Sanjeev Joshi Jan 2017

Sediment Transport And Channel Morphology Dynamics Of Highly Regulated Alluvial Rivers - A Case Study Of The Lowermost Mississippi River., Sanjeev Joshi

LSU Doctoral Dissertations

The Mississippi River delta is facing severe land loss. An urgent need exists to examine sediment transport and channel morphology dynamics along this highly engineered alluvial river that has shaped and will continue to shape its delta. This dissertation research focuses on investigating channel morphology dynamics and sediment transport in the recent three decades along a 327-km reach (from about 492 to 167 km upstream from the river’s outlet in the Gulf of Mexico) of the Lowermost Mississippi River (LmMR). The specific objectives of this research were to: 1) analyze riverbed adjustment, i.e., channel-bed aggradation or channel erosion at seven …

Go to article

Shallow Shear-Wave Seismic Analysis Of Point Bar Deposits Of False River, Louisiana, Martial James Morrison Jan 2017

Shallow Shear-Wave Seismic Analysis Of Point Bar Deposits Of False River, Louisiana, Martial James Morrison

LSU Master's Theses

Current point-bar complex models do not include subsurface unit bars as a normal feature. This study provides evidence for a potential buried unit bar amongst point-bar sediments of the large-scale, modern-day False River point-bar complex of the Mississippi River. We collect, process and interpret a two-dimensional, 150-m-long CMP seismic reflection profile that cuts perpendicularly across a major discontinuity surface in the False River point bar complex. The seismic source consists of a ground recoil device that fires a shotgun shell horizontally, producing shear waves. Multiple field experiments demonstrated which type of source and receiver provided the least amount of noise, …

Go to article

Microseismic Event Characteristics Associated With The Spatial And Temporal Stages Of Hydraulic Fracture Growth In Laboratory Experiments, Abigail Arielle Maxwell Jan 2017

Microseismic Event Characteristics Associated With The Spatial And Temporal Stages Of Hydraulic Fracture Growth In Laboratory Experiments, Abigail Arielle Maxwell

LSU Master's Theses

There are uncertainties in the exact mechanisms that occur during hydraulic fracture growth and the interactions of hydraulic fractures with pre-existing fractures. In some cases fracture growth is seen to be purely tensile and in others a combination of tensile and shear mechanisms. In order to develop a seismic model to explain fracture propagation, there is a need for a complete classification of the microseismic events occurring during fracturing using waveform characteristics such as frequency, duration and magnitude. This classification would allow for more accurate prediction of the behavior of the hydraulic fracture from its initiation to when it intersects …

Go to article

On-Site Sperm Cryopreservation For Aquatic Repository Development And User Group Linkage, William Martin Childress Jan 2017

On-Site Sperm Cryopreservation For Aquatic Repository Development And User Group Linkage, William Martin Childress

LSU Master's Theses

Although on-site cryopreservation of aquatic species sperm in nitrogen-vapor shipping dewars has been used for more than 30 yr, many limitations remain. Due to the size of shipping dewars, most studies are small scale and can only produce tens of samples. The freezing temperatures that can be achieved are also affected by the size of the dewar and the number of samples being frozen due to the heat load. In addition, often due to timing or remote location these samples cannot be shipped, and if they are shipped, quality can be lost and the samples must be discarded. The goal …

Go to article

Pesticide Concentrations In Water From A Southern Louisiana Marsh Influenced By The Mississippi River, Kara Leigh Callicott Jan 2017

Pesticide Concentrations In Water From A Southern Louisiana Marsh Influenced By The Mississippi River, Kara Leigh Callicott

LSU Master's Theses

The pesticides atrazine, chlorothalonil, and fipronil are common surface water contaminants due to their high rates of application and their chemical properties. This study investigates the introduction of contaminants into coastal wetlands via the Bayou Lamoque Mississippi River control structure in Plaquemines Parish, Louisiana. A protocol for environmental sampling using Continuous Low-level Aquatic Monitoring (C.L.A.M.) C-18 disks is described, along with effective solid phase extraction (SPE) and gas chromatography mass spectrometry (GC/MS) methodology for the determination of atrazine, chlorothalonil, and fipronil in surface water. Average concentrations of atrazine and chlorothalonil inside the Bayou Lamoque freshwater diversion structure for the months …

Go to article

Measuring The Effects Of Recycled Water On The Growth Of Three Algal Species: Tisochrysis Lutea, Chaetcoeros Calcitrans, And C. Muelleri In A Commercial-Scale Oyster Hatchery, Lisa Marie Bourassa Jan 2017

Measuring The Effects Of Recycled Water On The Growth Of Three Algal Species: Tisochrysis Lutea, Chaetcoeros Calcitrans, And C. Muelleri In A Commercial-Scale Oyster Hatchery, Lisa Marie Bourassa

LSU Master's Theses

Algal production is often the limiting factor in large-scale oyster hatcheries, and constant, reliable production is required to grow enough algae to support all oyster larvae and broodstock grown and conditioned in a hatchery. The algal rooms in the Michael C. Voisin Oyster Hatchery at Grand Isle, LA are temperature-controlled to maintain consistent temperature, but this hatchery is also unique in its ability to recycle natural seawater pumped from the northern Gulf of Mexico. Effects of recycling seawater on algal production in an oyster hatchery, however, are undocumented. In this study, Tisochrysis lutea, Chaetoceros calcitrans and C. muelleri were grown …

Go to article

Modeling The Influence Of Energy And Climate Megatrends On Future Costs And Benefits Of Marsh Creation In The Mississippi Delta, Adrian R. H. Wiegman Jan 2017

Modeling The Influence Of Energy And Climate Megatrends On Future Costs And Benefits Of Marsh Creation In The Mississippi Delta, Adrian R. H. Wiegman

LSU Master's Theses

Over 25% of Mississippi delta (MRDP) wetlands were lost over the past century. There is currently a major effort to restore the MRDP focused on a 50-year time horizon, a period during which the energy system and climate will change dramatically. I modeled hydraulic dredging to sustain marsh from 2016-2066 and 2016-2100 under a range of scenarios for sea level rise, energy price, and management regimes. A marsh elevation model was calibrated to data from MRDP marshes. I developed a model to simulate dredging costs based on the price of crude oil and a project efficiency factor. Crude oil prices …

Go to article

Development Of The Focal Plane Instrumentation Of The Separator For Capture Reactions (Secar), Kyle Joerres Jan 2017

Development Of The Focal Plane Instrumentation Of The Separator For Capture Reactions (Secar), Kyle Joerres

LSU Master's Theses

The SEparator for CApture Reactions (SECAR) is currently being developed at the National Superconducting Cyclotron Laboratory (NSCL) and the future Facility for Rare Isotope Beams (FRIB) for measurements of nuclear reactions critical for understanding energy generation and element synthesis in stellar explosions. SECAR is an electromagnetic recoil separator designed for sensitive measurements of radiative capture reactions using beams of proton-rich, short-lived isotopes at the energies relevant for explosive environments such as Type I X-ray bursts and classical novae. SECAR is designed to efficiently separate capture reaction products of interest from the incident beam by up to a factor of 10^17 …

Go to article

Interactive Web-Based Visualization Of Atomic Position-Time Series Data, Simron Thapa Jan 2017

Interactive Web-Based Visualization Of Atomic Position-Time Series Data, Simron Thapa

LSU Master's Theses

Extracting and interpreting the information contained in large sets of time-varying three dimensional positional data for the constituent atoms of simulated material system is a challenging task. This thesis work reports our initial implementation of a web-based visualization system and its use-case study. The system allows the users to perform the desired visualization task on a web browser for the position-time series data extracted from the local or remote hosts. It involves a pre-processing step for data reduction, which involves skipping uninteresting parts of the data uniformly (at full atomic configuration level) or non-uniformly (at atomic species level or individual …

Go to article

Differential Responses Of Soil Greenhouse Gas Production And Denitrification To Salinity Alterations Along A Wetland Salinity Gradient, Natalie Ceresnak Jan 2017

Differential Responses Of Soil Greenhouse Gas Production And Denitrification To Salinity Alterations Along A Wetland Salinity Gradient, Natalie Ceresnak

LSU Master's Theses

Coastal wetlands provide several valuable services, such as carbon (C) storage and nitrogen (N) removal. Although wetlands serve as net C sinks, wetland soils release greenhouse gases (GHGs) including carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Wetlands can buffer the influx of nitrate (NO3-) by transforming it into gaseous N (N2O, N2) through denitrification microbial pathway. Salinity is a regulator of soil biogeochemistry and long- (e.g. saltwater intrusion) and short-term (e.g. storm surges, river diversions) exposures may affect soil GHG production and denitrification. In this study, soil GHG production and denitrification enzyme activity (DEA) rates were examined over …

Go to article

Mesonets: Meso-Scale Weather And Climate Observations For The U.S., Rezaul Mahmood Jan 2017

Mesonets: Meso-Scale Weather And Climate Observations For The U.S., Rezaul Mahmood

School of Natural Resources: Faculty Publications

No abstract provided.

Go to article

Resilience In Ecotoxicology: Toward A Multiple Equilibrium Concept, Mirco Bundschuh, Ralf Schulz, Ralf B. Schäfer, Craig R. Allen, David G. Angeler Jan 2017

Resilience In Ecotoxicology: Toward A Multiple Equilibrium Concept, Mirco Bundschuh, Ralf Schulz, Ralf B. Schäfer, Craig R. Allen, David G. Angeler

School of Natural Resources: Faculty Publications

The term resilience describes stress-response patterns across scientific disciplines. In ecology, advances have been made to clearly define resilience based on underlying mechanistic assumptions. Engineering resilience (rebound) is used to describe the ability of organisms to recover from adverse conditions (disturbances), which is termed the rate of recovery. By contrast, the ecological resilience definition considers a systemic change, that is, when ecosystems reorganize into a new regime following disturbance. Under this new regime, structural and functional aspects change considerably relative to the previous regime, without recovery. In this context, resilience is an emergent property of complex systems. In the present …

Go to article

Assessment Of A Channel Catfish Population In A Large Open River System, A. J. Blank, M. J. Hamel, Jonathan J. Spurgeon, Mark A. Pegg Jan 2017

Assessment Of A Channel Catfish Population In A Large Open River System, A. J. Blank, M. J. Hamel, Jonathan J. Spurgeon, Mark A. Pegg

School of Natural Resources: Faculty Publications

Estimates of dynamic rate functions for riverine channel catfish, Ictalurus punctatus (Rafinesque), populations are limited. The open nature and inherent difficulty in sampling riverine environments and the propensity for dispersal of channel catfish impede estimation of population variables. However, contemporary population models (i.e. robust design models) can incorporate the open nature of these systems. The purpose of this study was to determine channel catfish population abundance, survival and size structure and to characterize growth in the lower Platte River, Nebraska, USA. Annual survival estimates of adult channel catfish were 13%–49%, and channel catfish abundance estimates ranged from 8,281 to 24,261 …

Go to article

A Novel Method For Determination Of Ammonium Isotope Ratios With Electrospray Ionization Mass Spectrometry, Rebecca J. Chmiel Jan 2017

A Novel Method For Determination Of Ammonium Isotope Ratios With Electrospray Ionization Mass Spectrometry, Rebecca J. Chmiel

Honors Theses

Nitrogen (15N) isotope tracer studies are an invaluable tool for understanding the rate of N transformations in the environment. A mechanistic understanding of N cycling is critical to management of excess N availability in freshwater and marine ecosystems. Conventional methods for measuring 15N:14N of dissolved inorganic nitrogen species are time consuming and require large sample volumes. Here, we present a technique for measuring 15N:14N in ammonium (NH4+) using electrospray ionization mass spectrometry (ESI-MS). NH4+ present in small volumes of sample (3 ml) is complexed with phenol via …

Go to article

I Remember It Like This: Essays, Robin C. Lewis Jan 2017

I Remember It Like This: Essays, Robin C. Lewis

Honors Theses

This thesis is composed of eleven personal essays. As an Environmental Policy senior, I wanted to write down some of my formative stories—not just any stories, but those that may reveal the environmental thread in my life, which, I believe, was somehow instilled in me by my parents. This thread has followed me from Texas to Maine, from childhood to almost twenty-three. It has been supported and tested by various characters along the way, sometimes growing faint, other times stronger. As I prepare for something new, I’ve found it valuable to look back on the people and landscapes and stories …

Go to article

An Alternative Approach To Training Sequence-To-Sequence Model For Machine Translation, Vivek Sah Jan 2017

An Alternative Approach To Training Sequence-To-Sequence Model For Machine Translation, Vivek Sah

Honors Theses

Machine translation is a widely researched topic in the field of Natural Language Processing and most recently, neural network models have been shown to be very effective at this task. The model, called sequence-to-sequence model, learns to map an input sequence in one language to a vector of fixed dimensionality and then map that vector to an output sequence in another language without any human intervention provided that there is enough training data. Focusing on English-French translation, in this paper, I present a way to simplify the learning process by replacing English input sentences by word-by-word translation of those sentences. …

Go to article

Photochemical Generation Of Carbenes And Ketenes From Phenanthrene-Based Precursors Part I: Dimethylalkylidene Part Ii: Diphenylketene, Tarini S. Hardikar, Tarini Hardikar Jan 2017

Photochemical Generation Of Carbenes And Ketenes From Phenanthrene-Based Precursors Part I: Dimethylalkylidene Part Ii: Diphenylketene, Tarini S. Hardikar, Tarini Hardikar

Honors Theses

Previous studies have shown that the photolysis of phenanthrene-based cyclopropyl precursors can generate carbenes. In this work, a novel phenanthrene precursor was synthesized and photolyzed to generate the dimethylalkylidene carbene, which was subsequently trapped by cyclohexene. The car- bene was not prone to an internal rearrangement as some other carbenes are, and instead favored the intermolecular addition reaction. The precursor also underwent a rearrangement via pericyclic processes. A theoretical analysis of the potential energy surface of the system is presented using coupled cluster and density functional methods. Preliminary analysis for the precursor via time-resolved laser flash photolysis (LFP) was performed. …

Go to article

America's National Parks And The Anthropocene: Addressing The Present To Accommodate The Future In Acadia National Park, Sophie A. Swetz Jan 2017

America's National Parks And The Anthropocene: Addressing The Present To Accommodate The Future In Acadia National Park, Sophie A. Swetz

Honors Theses

In 2000, atmospheric chemist, Paul J. Crutzen, and limnologist, Eugene Stoermer, formally proposed the idea of “the Anthropocene,” a new geologic epoch in which humans are the dominant force shaping the Earth. To claim the Anthropocene's existence is to declare that human actions have altered the Earth in such a way that geologic indicators render it a distinct epoch in the stratification of geologic time. This new epoch emerges as a consequence of increased technological development employed to accommodate an anthropocentric human existence. That is, rapid advancements in technology have driven the transformation from a primarily naturally controlled planet to …

Go to article

Some Examples Of The Interplay Between Algebra And Topology, Joseph D. Malionek Jan 2017

Some Examples Of The Interplay Between Algebra And Topology, Joseph D. Malionek

Honors Theses

This thesis presents several undergraduate and graduate level concepts in the fields of algebraic topology and topological group theory in a manner which requires very little mathematical background of the reader. It uses non-rigorous interpretations of concepts while introducing the reader to the rigorous ideas with which they are associated. In order to give the reader an idea of how the fields of algebra and topology are closely affiliated, the paper goes over five main concepts, the fundamental group, homology, cohomology, Eilenberg-Maclane spaces, and group dimension.

Go to article

Correcting Pedestrian Dead Reckoning With Monte Carlo Localization Boxed For Indoor Navigation, Akira T. Murphy Jan 2017

Correcting Pedestrian Dead Reckoning With Monte Carlo Localization Boxed For Indoor Navigation, Akira T. Murphy

Honors Theses

Localization of phones is a ubiquitous part of the modern mobile electronics landscape. However, there are many situations where the current method of networked localization fails. A Pedestrian Dead Reckoning System where the location of the user is calculated by counting the steps and direction of the user was implemented as an iOS app with python for data analysis. A novel algorithm for wireless sensor localization using Ad-Hoc Bluetooth networks was proposed. A small experiment was performed proving that the system is nearly equal to state of the art algorithms.

Go to article

Development Of A Low-Energy Monoenergetic Electron Separator, Sergio Martín López Cáceres Jan 2017

Development Of A Low-Energy Monoenergetic Electron Separator, Sergio Martín López Cáceres

LSU Master's Theses

The aim of this project is to build a prototype device that can select electrons of certain energy in order to have a monoenergetic beam suitable for the characterization of radiation detectors. Current options for sources of electrons are either from radioisotopes or accelerator facilities. Radioisotope sources are not tunable in energy since they depend on the nuclear and atomic structures of the daughter nucleus. On the other hand, even though accelerators offer the feature of a variable energy beam, they have limited availability and are not typically run at low intensities. Therefore, the motivation for this thesis is the …

Go to article

Database Plan Quality Impact On Knowledge-Based Radiation Therapy Treatment Planning Of Prostate Cancer, Phillip Douglas Hardenbergh Wall Jan 2017

Database Plan Quality Impact On Knowledge-Based Radiation Therapy Treatment Planning Of Prostate Cancer, Phillip Douglas Hardenbergh Wall

LSU Master's Theses

Purpose: Knowledge-based planning (KBP) leverages plan data from a database of previously treated patients to inform the plan design of a new patient. This work investigated bladder and rectum dose-volume prediction improvements in a common KBP method using a Pareto plan database in VMAT planning for prostate cancer. Methods: We formed an anonymized retrospective patient database of 124 VMAT plans for prostate cancer treated at our institution. From these patient data, two plan databases were compiled. The clinical plan database (CPD) contained planning data from each patient’s clinical plan, which were manually optimized by various planners. The multi-criteria optimization database …

Go to article

The Relationship Between The Timing Of Hydrocarbon Generation Between The Bristol Bay Depositional Basin And The Port Moller Area And Southern Portion Of The Bristol Bay Basin Of The Alaska Peninsula, Claire Rochelle Jones Jan 2017

The Relationship Between The Timing Of Hydrocarbon Generation Between The Bristol Bay Depositional Basin And The Port Moller Area And Southern Portion Of The Bristol Bay Basin Of The Alaska Peninsula, Claire Rochelle Jones

LSU Master's Theses

The Alaska Peninsula has been the target of oil and gas exploration throughout much of the 20th century. Although most exploration efforts have focused on the Cook Inlet area, the geological setting of the Alaskan Peninsula suggests that economically viable resources may be located further south on the northern side bordering Bristol Bay (Port Moller area). This study investigates the relation of petroleum system elements between the northern and southern section of the Alaskan Peninsula with a particular focus on the potential for petroleum accumulation on the southern section close to Herendeen Bay. The analysis included the integration of a …

Go to article

First Prev Next Last