Digital Commons Network^™

Coastal Wetland Subsidence Arising From Local Hydrologic Manipulations, R. Eugene Turner

Faculty Publications

Twenty-three estimates of soil subsidence rates arising under the influence of local hydrologic changes from flap-gates, weirs, dikes, and culverts in tidal wetlands were compared to 75 examples of subsidence in drained agricultural wetlands. The induced subsidence rates from these hydrologic modifications in tidal wetlands can continue for more than 100 years, and range between 1.67 to 0.10 cm yr−1 within 1 to 155 years after the hydrologic modifications commence. These subsidence rates are lower than in freshwater wetlands drained for agricultural purposes, decline with age, and are significant in comparison to the rates of global sea level rise or …

Inorganic Nitrogen Transformations At High Loading Rates In An Oligohaline Estuary, R. Eugene Turner, Q. Dortch, Nancy N. Rabalais

Faculty Publications

A well-defined nitrogen retention and turnover budget was estimated for a shallow oligohaline lake (Lake Pontchartrain, Louisiana, USA). In 1997 a month-long diversion of the Mississippi River filled the Lake with highly concentrated river water (80 µM nitrate) and lowered the salinity to 0 psu within 2 weeks. After the spillway was closed the Lake mixed with estuarine tidal waters and came to equilibrium over 4 months with the riverine, atmospheric and offshore water nitrogen sources. A flushing rate of 1.78% d−1 was estimated by analyzing a plot of ln salinity versus time for the first 120 days after the …

Below-Ground Biomass In Healthy And Impaired Salt Marshes, R. Eugene Turner, Erick M. Swenson, Charles S. Milan, James M. Lee, Thomas A. Oswald

Faculty Publications

Twelve salt marshes in south Louisiana (USA) were classified as either ‘impaired’ or ‘healthy’ before a summer sample collection of above- and below-ground biomass and determination of sediment accretion rates. The above-ground biomass of plant tissues was the same at both impaired and healthy salt marshes and was not a good predictor of marsh health. However, below-ground root biomass in the upper 30 cm was much lower in the impaired marshes compared to the healthy marshes. Compromises to root production apparently occur before there is an obvious consequence to the above-ground biomass, which may quickly collapse before remedial action can …

Suspended Sediment, C, N, P, And Si Yields From The Mississippi River Basin, R. Eugene Turner, Nancy N. Rabalais

Faculty Publications

The annual loads of C,N,P, silicate, total suspended sediment (mass) and their yields (mass area−1) were estimated for six watersheds of the Mississippi River Basin (MRB) using water quality and water discharge records for 1973 to 1994. The highest load of suspended sediments is from the Missouri watershed (58 mt km2 yr−1), which is also the largest among the six major sub-basins. The Ohio watershed delivers the largest load of water (38%). The Upper Mississippi has the largest total nitrogen load (32%) and yield (1120 kg TN km2 yr−1). The loading of organic carbon, total phosphorus and silicate from the …

New Insights Into The Binding Site Formation And The Performance Of Molecularly Imprinted Polymers, Hyunjung Kim

LSU Doctoral Dissertations

Molecularly imprinted polymers (MIPs) are finding important applications in the field of separation science, catalysis, sensor, and immunoassays. To optimize the performance of the MIPs, it is essential to understand the underlying mechanism of the process. This research focuses on understanding binding site formation and performance, and improvement of the MIPs. Chapter 1 introduces the concept of the MIPs, and binding isotherm and affinity distribution of heterogeneous binding sites in the MIPs. Chapter 2 describes fundamental studies conducted to understand the binding site formation of the MIPs. The number of binding sites (N) and the number average association constant (Kn) …

Applications Of The Titanium Catalyzed Cyclocarbonylation Towards Natural Product Syntheses, Jongtae Yang

LSU Doctoral Dissertations

Recently an efficient methodology, a hetero Pauson-Khand reaction, based on titanium-catalyzed cyclocarbonylation of tethered enals for the general preparation of ¥ã-butyrolactone rings, which are typically embedded in polycyclic systems of many natural products was reported. To demonstrate this new strategy, the total syntheses of the natural products asteriscanolide and ginkgolide were investigated. The first part of this work is dedicated to synthetic efforts toward the total synthesis of asteriscanolide. Approaches highlighted by the [2,3]-Wittig rearrangement, the thermal silyloxy-Cope rearrangement, and a titanium-catalyzed cyclocarbonylation, which is the pivotal step to afford the ¥ã-butyrolactone ring. This study firmly established the utility of …

Application Of Disturbance Theory To Assess Impacts Associated With A Three-Dimensional Seismic Survey In A Freshwater Marsh In Southwest Louisiana, Aaron Stuard Bass

LSU Doctoral Dissertations

This study examined various practical and theoretical aspects of disturbance in a coastal wetland marsh in southern Louisiana. A literature review approached disturbance ecology from both practical and theoretical perspectives and assessed its applicability to developing broad predictive models. However, specific knowledge of environmental variables, competitive relationships, and the interactive effects of multiple disturbances are required for meaningful usage of these models. The Lacassine National Wildlife Refuge (LNWR) proved to be an ideal laboratory to test various aspects of ecological disturbance theory. I found that the primary disturbances affecting the LNWR have been hurricanes, droughts, water-level manipulations, prescribed burning, oil …

Synthesis, Separation And Reactivities Of Multidentate Phosphine Ligands And Investigation Into Dirhodium Hydroformylation And Hydrocarboxylation Catalysis, David Aubry

LSU Doctoral Dissertations

A dirhodium homogeneous hydroformylation catalyst based on a tetraphosphine ligand, rac-Et₂PCH₂CH₂P(Ph)CH₂P(Ph)CH₂CH₂PEt₂, rac-et,ph-P4, is under investigation. The ligand synthesis produces a racemic mixture and a facile and efficient method of separation of the racemic and meso diastereomers was achieved through reaction of et,ph-P4 with two equivalents of NiCl₂ in EtOH to yield an almost quantitatively isolable precipitate of meso-Ni₂Cl₄(et,ph-P4) and the soluble rac-Ni₂Cl₄(et,ph-P4). Subsequent cyanolysis of these complexes liberates the et,ph-P4 ligand, and the …

Dynamics Of Complex Polymer Solutions: Putting Diffusion To Work And Exploring Rigid Rod Diffusion, Garrett John Doucet

LSU Doctoral Dissertations

This dissertation is concerned with random coil and rodlike polymer diffusion in complex solutions. The development of fluorescence photobleaching recovery, FPR, as a technique to determine polymer molecular weight distributions by measuring the diffusion distribution and converting it to a molecular weight distribution using a calibration curve is first covered. Fluorescently tagged probes were individually dissolved in polymer solutions at negligible amounts and measured with FPR to construct the calibration curve of self-diffusion vs. molecular weight. Once calibration curves were constructed, bimodal distributions were separated using the matrices corresponding to the calibration curves. The diffusion of the probes and separation …

Electronic Structural Investigations Of Bi- And Polymetallic Complexes Using Quantum Mechanical Methods, Zakiya Sheni Wilson

LSU Doctoral Dissertations

Understanding the dynamics influencing chemical reactivity is essential for properly exploiting matter into more useful purposes. In that manner, computational chemistry is a tool frequently used to study chemical properties at the most intimate level, i.e. the single molecule.

With this work, we probe the chemistry governing a variety of multi-faceted bi- and polymetallic compounds. To date our research consists of four major projects: bimetallic rhodium-catalyzed hydroformylation and aldehyde-water shift hydrocarboxylation catalysis; a novel linear M-H-M interaction in a bridged bis(dialkylphosphino)methane complex of nickel; and CeBe₁₃, a heavy fermion conductor. Computational investigations on these systems allow us to …

Leaf Litter Processing By Macrodetritivores In Natural And Restored Neotropical Mangrove Forests, Gary Eugene Raulerson

LSU Doctoral Dissertations

Knowledge of mangrove litter dynamics is crucial to an understanding of the energetic links between mangrove ecosystems and nearby estuaries and coastal waters. Previous research into the role played by macrodetritivores in Neotropical mangrove litter processing has been contradictory. This study used leaf tethering to examine the effects of macrodetritivores on initial rates of mangrove litter degradation in South Florida, USA. Leaf litter dynamics experiments were run in both natural and restored mangrove forests to assess functionality of the restoration projects. Although less important than in some other parts of the world (e.g., the Indo-Pacific), macrodetritivores played a significant role …

Address Optimizations For Embedded Processors, Sai Pinnepalli

LSU Doctoral Dissertations

Embedded processors that are common in electronic devices perform a limited set of tasks compared to general-purpose processor systems. They have limited resources which have to be efficiently used. Optimal utilization of program memory needs a reduction in code size which can be achieved by eliminating unnecessary address computations i.e., generate optimal offset assignment that utilizes built-in addressing modes. Single offset assignment (SOA) solutions, used for processors with one address register; start with the access sequence of variables to determine the optimal assignment. This research uses the basic block to commutatively transform statements to alter the access sequence. Edges in …

Spectroscopic And Synthetic Studies Relating To A Dirhodium Hydroformylation Catalyst, Petia Gueorguieva Gueorguieva

LSU Doctoral Dissertations

The main goal of this dissertation research was to further study and characterize our bimetallic hydroformylation catalyst, rac-[Rh₂(nbd)₂(et,ph-P4)](BF₄)₂, and to fully identify the catalytically inactive mono- and dirhodium complexes formed upon fragmentation of the catalyst under hydroformylation conditions. Various in situ NMR methods such as 1D ¹H and ³¹P, and 2D COSY, HMBC, and HMQC were employed and indicated the formation of the key catalyst, [rac-Rh₂H₂(μ-CO)₂(CO)₄(et,ph-P4)]²⁺, 4, and a number of other Rh-phosphine species on and off the catalytic cycle. …

Synthesis And Characterization Of Superparamagnetic Silica--Homopolypeptide Composite Particles, Sibel Turksen

LSU Doctoral Dissertations

Hierarchical construction and characterization of core-shell composite particles of interest are presented. The research described shows interest in new types of polymers that provide chirality and responsiveness which have been ignored for so long. The general synthetic design described in this document can be readily used as a model for other systems. Core-shell composite systems of interest consist of silica or silica-coated cobalt cores grafted with a homopolypeptide shell, mostly poly(epsilon-carbobenzyloxy-L-lysine) or poly(gamma-benzyl-L-glutamate). Core particles were decorated with amino groups through a silylation reaction. The amino groups initiated the polymerization (with attachment) of N-carboxyanhydride (NCA) monomers, resulting in a homopolypeptide …

Synthesis, Characterization And Study Of Novel Reagents For The Detection Of Saccharides And Amino Acids, Nadia Nadette St. Luce

LSU Doctoral Dissertations

The design of synthetic receptors for the recognition and sensing of saccharides and amino acids is currently a major challenge. This is due to inherent structural similarity and a lack of chromophoric or fluorophoric properties of these compounds. The synthesis and study of novel detection agents for bioactive molecules as well as mechanistic studies are presented herein. The elucidation of the mechanism by which tetraarylboronic acid resorcinarene interact with sugar molecules and promote a solution color change is explored. This vast collaborative study, reveals that DMSO solutions of boronic acid functionalized resorcinarene macrocycles afford visual color changes upon heating or …

Investigation Of Structure-Property Relationships Of Heavy-Fermion Materials, Robin Macaluso

LSU Doctoral Dissertations

This work focuses on how local structural features influence large effective masses, magnetism, and superconductivity that are yet to be understood in heavy-fermion materials. Three sets of structurally-related materials are discussed in light of dimensionality, layering effects, choice of transition metal, coordination, and structural distortions: LnnMIn3n+2 (Ln = La, Ce; n = 1, 2, ‡; M = Co, Rh, Ir), CePdGa6, and Ce2PdGa12, and CeNiSb3. The LnnMIn3n+2 (n = 1, 2, ‡; Ln = La, Ce; M = Rh, Ir) intergrowth homologous series presents a unique opportunity to study structure-property relationships. LnnMIn3n+2 (Ln = La, Ce; n = 1, 2; …

Which Mean Do You Mean?: An Exposition On Means, Mabrouck K. Faradj

LSU Master's Theses

The objective of this thesis is to give a brief exposition on the theory of means. In Greek mathematics, means are intermediate values between two extremes, while in modern mathematics, a mean is a measure of the central tendency for a set of numbers. We begin by exploring the origin of the antique means and list the classical means. Next, we present an overview of the theories of binary means and n-ary means. We include a general discussion on axiomatic systems for means and present theorems on properties that characterize the most common types of means.

The Syntheses Of Novel Indicators And Materials For Chiral Separation, Rolanda Johnson

LSU Doctoral Dissertations

The colorimetric properties of resorcinarene solutions had not been fully investigated since von Baeyer's initial synthesis. We find that the solutions containing resorcinarene macrocycles develop color upon heating or standing. In the presence of saccharides, these solutions exhibit significant color changes which are readily observable by visual inspection. We determined that the solution color is due to macrocycle ring opening and oxidation. The optical responses to saccharides are due to complexation of the sugar with the acyclic chromophores. We have applied these mechanistic insights towards the challenging problems of the visual detection of saccharides and other important biologically analytes. In …

Influence Of The Marsh Edge On The Structure And Trophic Ecology Of The Fish And Macroinvertebrate Community In A Louisiana Estuarine Ecosystem, Guillermo Duque

LSU Doctoral Dissertations

Habitat degradation of saltmarsh ecosystems reduces the suitability of the marsh as permanent environments for resident species and seasonal nursery grounds for transient fauna. This study was conducted in Terrebonne-Timbalier bays near Cocodrie, Louisiana. Fishes and macroinvertebrates were collected using a drop sampler in marsh-edge and open-water habitat types, in three locations (i.e., pond, channel, and bay), and four seasons (Fall of 2000, Winter of 2000-2001, and Spring and Summer of 2001). The specific objectives of this study were: (1) to determine the difference in composition and structure of fish and macroinvertebrate communities, (2) to establish the food habits of …

A Distributed Quadtree Dictionary Approach To Multi-Resolution Visualization Of Scattered Neutron Data, Rion Dooley

LSU Doctoral Dissertations

Grid computing is described as dependable, seamless, pervasive access to resources and services, whereas mobile computing allows the movement of people from place to place while staying connected to resources at each location. Mobile grid computing is a new computing paradigm, which joins these two technologies by enabling access to the collection of resources within a user's virtual organization while still maintaining the freedom of mobile computing through a service paradigm. A major problem in virtual organization is needs mismatch, in which one resources requests a service from another resources it is unable to fulfill, since virtual organizations are necessarily …

Asymptotic Laplace Transforms, Claudiu Mihai

LSU Doctoral Dissertations

In this work we discuss certain aspects of the classical Laplace theory that are relevant for an entirely analytic approach to justify Heaviside's operational calculus methods. The approach explored here suggests an interpretation of the Heaviside operator ${cdot}$ based on the "Asymptotic Laplace Transform." The asymptotic approach presented here is based on recent work by G. Lumer and F. Neubrander on the subject. In particular, we investigate the two competing definitions of the asymptotic Laplace transform used in their works, and add a third one which we suggest is more natural and convenient than the earlier ones given. We compute …

Quantification Of Marine Sediment Properties From Planar And Volumetric Pore Geometries, Allen Hagerman Reed

LSU Doctoral Dissertations

Pore geometry and topology are important determinants of sediment physical properties, such as porosity and permeability. They also influence processes that occur in the sediment, such as acoustic propagation, attenuation, and dispersion, single- and multi-phase fluid flow, and hydrodynamic dispersion. This study uses images to evaluate pore geometry and topology of ooid (subspherical particles) and siliclastic (angular quartz) sand that was collected from the marine environment south of Bimni Bahamas and Ft. Walton Beach, FL, respectively. Image analysis techniques and predictive tools enable insight into the relationships among sediment pore geometry, topology, and physical properties for these differently shaped sands. …

State-Level Environmental Risk Perception: An Analysis Of 20 Comparative Risk Reports, Mandy Green

LSU Master's Theses

Research was conducted to identify the states that compiled Comparative Risk Reports and the year in which the study was completed. The information relating to the type of committee that compiled the risk report and the final risk rankings was examined. State Comparative Risk Reports were collected for twenty states and the risk rankings that each state compiled were reviewed to determine which states ranked third generation environmental problems and the ranking that those problems were given. The risk reports compiled by each state were also used to determine which states ranked natural resource based problems and the ranking that …

Mortality Of Pen-Raised White-Tailed Deer (Odocoileus Virginianus) Released On Three Areas In Louisiana, Barret Keith Fortier

LSU Master's Theses

I monitored 60 radio-collared and tagged pen-raised white-tailed deer (Odocoileus virginianus) to ascertain mortality rates on three areas in Louisiana from April 2001 - April 2002. Two of 60 were not used in the analysis because mortality occurred from complications with darting and an affixed radio-collar. Study deer were exposed to legal hunting mortality only if they emigrated from the three study areas. Twenty deer were released to the wild on the Louisiana State University Deer Study Area (LSUDSA) (4,810 ha), where 9 of 20 (45%) suffered mortality. Harvest accounted for 56%, vehicles 22%, and other 22% of the mortality …

An Evaluation Of Reference Evapotranspiration Models In Louisiana, Royce Landon Fontenot

LSU Master's Theses

Daily and monthly output from seven evapotranspiration models (FAO-24 Radiation, FAO-24 Blaney-Criddle, Hargreaves-Samani, Priestly-Taylor, Makkink, and Turc) have been tested against reference evapotranspiration data computed by the FAO-56 Penman-Monteith model to assess the accuracy of each model in estimating grass-reference evapotranspiration in Louisiana. Models were compared at eight stations of the Louisiana Agriclimate Information System using data from December 2002 to November 2003. Comparisons were also made using three composite regions: statewide, inland, and coastal. A pan evaporation to reference evapotranspiration model (FAO-24 Pan Evaporation) was also tested against daily grass reference evapotranspiration from the FAO-56 Penman-Monteith model using data …

Effects Of Spinning-Wing Decoys On Flock Behavior And Hunting Vulnerability Of Local And Migrant Mallards And Other Ducks In Minnesota, Michael L. Szymanski

LSU Master's Theses

Waterfowl managers in Minnesota and other states are concerned that increased kill rates associated with the use of spinning-wing decoys (SWDs) may negatively affect local breeding populations of mallards (Anas platyrhynchos). I conducted 219 experimental hunts to evaluate hunting vulnerability of mallards to SWDs during the 2002 duck-hunting season in Minnesota. Following experimental hunts, I asked volunteer hunters to complete post-hunt questionnaires to document their hunting experience, and their use and opinions of SWDs. Finally, I used stable isotope methodology to determine natal origins of HY mallards killed during experimental hunts. I found that mallard flocks (≥1 duck) were 2.91 …

Properties Of Borate-Treated Strandboard Bonded With Pmdi Resin, Yiqiang Zhou

LSU Master's Theses

Random strandboards from mixed southern wood species were manufactured using calcium borate (CB) and zinc borate (ZB) as chemical additives and polymeric methylene diphenylmethane disocyanate (pMDI) as resin. There were four target levels of borate loading and two levels of resin content. Panel properties, including modulus of elasticity (MOE), modulus of rupture (MOR), internal bond (IB) strength, linear expansion (LE), thickness swelling (TS), leachability, and swelling and strength retention properties under cyclic relative humidity, were measured. The influence of borate content, borate type, and resin content on various properties was analyzed. It was found that the addition of borate negatively …

Software Architecture: Styles And Representational Schemes, Somo Subro Banerjee

LSU Master's Theses

Software architecture is being widely used today to describe a very high-level design methodology of large software systems. Software architecture represents the overall structure of a system in an abstract, structured manner. A good architectural representation scheme holds the key to the effectiveness of a software architecture description and usage. In this work we look at architectural styles and architectural representation schemes. We propound the idea that the layered architectural model is a suitable candidate for a generalized architectural style and that it can cater to many different problem domains, other than the message-passing systems it has traditionally been used …

Lattice Boltzmann Simulation Of Flow Around Bluff-Bodies, Kevin Tubbs

LSU Master's Theses

In this work, results from a 2-D Lattice Boltzmann (LB) solver are presented simulating flow past rectangular square cylinders at low Reynolds numbers (< 250). The LBGK equation is a hyperbolic equation that approximates the Navier Stokes equations in the nearly incompressible limit. It is a system of 9 one dimensional partial differential Hamiltonian-Jacobian equations, consisting of an advection and diffusive portion. The LB method is an alternative computational fluid dynamics (CFD) method used to numerically predict incompressible viscous flow. The current LB method uses a statistical mechanics formulation to solve the Boltzmann equation. The LB model captures the nonlinear Navier Stokes advection terms using linear streaming operators. In this thesis, the LB model is classified as an explicit, Lagrangian, finite-hyperbolicity and weakly compressible approximation of the Navier Stokes equations. The momentum flux tensor is captured locally as opposed to a pressure field eliminating the need to solve the Poisson equation. This allows the fluid structure interactions (FSI) behavior to be calculated elegantly at the interface through the mesoscopic momentum transfer between the fluid and structure. At this level, the forces are simultaneously calculated. The LB equations are discretized both in time and phase space using a standard D2Q9 lattice model. Validation tests for flow around single square cylinders at different aspect ratio at low Reynolds numbers are presented. Good agreement with other investigators is achieved. Flow past multiple bluff bodies (representing building in a city) is also presented. The vortex shedding simulations presented provide preliminary indications in terms of St that the LB method can be used to simulate high Re flow.

Regional-Scale Eutrophication Models: A Bayesian Treed Model Approach, Angelina Freeman

LSU Master's Theses

Utilizing Bayesian hierarchical techniques, regional-scale eutrophication models were developed for use in the Total Maximum Daily Load (TMDL) process. The Bayesian tree-based (BTREED) approach allows association of multiple environmental stressors with biological responses, and quantification of uncertainty sources in the water quality model. Simple parametric models are often inadequate for describing complex datasets; the BTREED approach partitions the dataset, and describes the localized subsets of data with linear models, thereby providing a comprehensive representation of stressor and response interactions. Nutrient criteria data for lakes, ponds and reservoirs across the United States were obtained from the Environmental Protection Agency (U.S. EPA) …