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Articles 1 - 30 of 119
Full-Text Articles in Physical Sciences and Mathematics
On The Nature Of Connectivity Types, Miao Xu
Dynamical Systems And The Logistic And Tent Maps, Kathleen Larkin Spires
Dynamical Systems And The Logistic And Tent Maps, Kathleen Larkin Spires
Honors Theses
No abstract provided.
Ensight, Jonathan Hefner
An Investigation Of Modified Superconductivity Through Structural Alteration Of Mgcni3 And Mgb2, Nathan L. Henderson
An Investigation Of Modified Superconductivity Through Structural Alteration Of Mgcni3 And Mgb2, Nathan L. Henderson
Honors Theses
No abstract provided.
Automatic Segmentation Of Magnetic Resonance Images Of The Brain, Kirk V. N. Spence
Automatic Segmentation Of Magnetic Resonance Images Of The Brain, Kirk V. N. Spence
LSU Doctoral Dissertations
Magnetic resonance imaging (MRI) is a technique used primarily in medical settings to produce high quality images of the human body’s internal anatomy. Each image is of a thin slice through the body, with the typical distance between slices being a few millimeters. Brain segmentation is the delineation of one or more anatomical structures within images of the brain. It promotes greater understanding of spatial relationships to aid in such tasks as surgical planning and clinical diagnoses, particularly when the segmented outlines from each image slice are displayed together as a surface in three-dimensions. A review of the literature indicates …
Economic Valuation Of Natural Resource Management: A Case Study Of The Benuaq Dayak Tribe In Kalimantan, Indonesia, Indah D. Kusuma
Economic Valuation Of Natural Resource Management: A Case Study Of The Benuaq Dayak Tribe In Kalimantan, Indonesia, Indah D. Kusuma
LSU Doctoral Dissertations
The unavailability of total economic values of indigenous people in Indonesia, both in the short and long term, has created the rejection of their existences in the forest area. The purpose of this study is to estimate the total economic value of sustainable forest management conducted by indigenous tribes in Indonesia using total economic value concepts. The tribe’s total economic value is expressed by estimating the use value, indirect use value and non-use value. The study used benefit transfer and survey methods using questionnaires to estimate the tribe’s total economic value. The estimated total economic value of the Benuaq Dayak …
Nekton Utilization Of Black Mangrove (Avicennia Germinans) And Smooth Cordgrass (Spartina Alterniflora) Sites In Southwestern Caminada Bay, Louisiana, Melanie Christine Caudill
Nekton Utilization Of Black Mangrove (Avicennia Germinans) And Smooth Cordgrass (Spartina Alterniflora) Sites In Southwestern Caminada Bay, Louisiana, Melanie Christine Caudill
LSU Master's Theses
This is the first study to compare nekton use and habitat value among Spartina alterniflora (Spartina), Avicennia germinans (black mangrove), and transition (S. alterniflora and A. germinans) sites within Louisiana's salt marsh-mangrove ecotone. Fishes and crustaceans were collected in Caminada Bay during fall 2003 and spring 2004 using 4 m2, bottomless lift nets. Although analyses were unable to demonstrate significant differences in fish (p=0.0753) and crustacean (p=0.1457) densities and species composition (p=0.8801) across sites, habitat-specific trends in nekton use were evident. Fishes, including gulf killifish and sheepshead minnows, showed affinities for the Spartina site, while crustaceans, especially white shrimp, were …
Restoration Success Of Backfilling Canals In Coastal Louisiana Marshes, Joseph Baustian
Restoration Success Of Backfilling Canals In Coastal Louisiana Marshes, Joseph Baustian
LSU Master's Theses
The need for effective marsh restoration techniques in Louisiana is a pressing issue as the state continues to lose coastal wetlands. Returning spoil banks to canals, known as "backfilling", is an attractive restoration option because it restores marsh, prevents future wetland loss, and is cost effective. The direct conversion of marsh to canals and spoil banks accounted for over 22% of Louisiana's wetland loss from 1930 to 1990, and the indirect losses associated with canal dredging are even larger. The restoration success of 30 canals, backfilled twenty years ago, was examined in this study and compared to restoration success shortly …
Platform Recruited Reef Fish, Phase I: Do Platforms Provide Habitat That Increase The Survival Of Juvenile Reef Fishes?, Lauren Kay Nowling
Platform Recruited Reef Fish, Phase I: Do Platforms Provide Habitat That Increase The Survival Of Juvenile Reef Fishes?, Lauren Kay Nowling
LSU Master's Theses
There are currently over 4000 functioning oil and gas platforms in the northern Gulf of Mexico (Gulf). Platform operations, and their prior drilling operations, produce trace amounts of lead, barium, vanadium, and lanthanum residues that are leached into the surrounding waters and are deposited on the sea floor. These residues have isotopic ratios different from those typical of the Gulf seafloor and can be used as harmless ‘fingerprints’ if they become incorporated into hard-parts or tissues in fishes associated with oil and gas platforms. From 2002 to 2004, 115 red snapper were collected from oil and gas platforms and artificial …
The Stable Isotope Stratigraphy And Paleosols Of North America's Most Southern Exposure Of Late Paleocene/Early Eocene Fossiliferous Continental Deposits: Documenting The Initial Eocene Thermal Maximum In Big Bend National Park, Texas, Paul David White
LSU Doctoral Dissertations
A chemostratigraphic section across the Paleocene/Eocene boundary, using the stable isotopes of carbon and oxygen, has been developed for North America's most southern exposure of early Paleogene continental deposits in which the boundary is constrained by fossil mammals. A negative carbon excursion has been identified within C24r. The range in d13C values is from -8.1 to -13.2‰. Until the development of the chemostratigraphic section it was uncertain if the earliest Eocene was recorded in Big Bend. An early Wasatchian (Wa1) fossil site occurs stratigraphically higher than the carbon excursion and has yielded the stratigraphically lowest Hyracotherium in the …
Characterization Of Aged Polymer Modified Asphalt Cements For Recycling Purposes, Codrin Daranga
Characterization Of Aged Polymer Modified Asphalt Cements For Recycling Purposes, Codrin Daranga
LSU Doctoral Dissertations
Since polymer modified asphalt cement (PMAC) has been employed for a decade, the lifetime and wear on some of these pavements is reaching a stage where resurfacing is necessary. This research focuses on the characterization of aged polymer modified asphalt cements (PMAC) to evaluate their potential for recycling. A styrene-butadiene-styrene tri-block (SBS) polymer modified asphalt cement was selected and characterized using standard asphalt binder qualification techniques, i.e., the Superpave PG protocol. We developed a procedure to characterize the relative concentration of polymer in asphalt cements by gel permeation chromatography (GPC). Infrared spectrographic, thermogravimetric and rheological techniques were used to identify …
Medical Image Enhancement, Alina Monica Trifas
Medical Image Enhancement, Alina Monica Trifas
LSU Doctoral Dissertations
Each image acquired from a medical imaging system is often part of a two-dimensional (2-D) image set whose total presents a three-dimensional (3-D) object for diagnosis. Unfortunately, sometimes these images are of poor quality. These distortions cause an inadequate object-of-interest presentation, which can result in inaccurate image analysis. Blurring is considered a serious problem. Therefore, “deblurring” an image to obtain better quality is an important issue in medical image processing. In our research, the image is initially decomposed. Contrast improvement is achieved by modifying the coefficients obtained from the decomposed image. Small coefficient values represent subtle details and are amplified …
Do Predator Exclusion, Position, And Plant Architecture Influence Hydrilla-Dwelling Macroinvertebrate Communities?, Jonathan C. Fisher
Do Predator Exclusion, Position, And Plant Architecture Influence Hydrilla-Dwelling Macroinvertebrate Communities?, Jonathan C. Fisher
LSU Master's Theses
Hydrilla verticillata invaded south central Louisiana during the 1970s subsequently becoming the dominant submerged macrophyte in floodplain habitats of the Atchafalaya River Basin. The effects of hydrilla on littoral habitat structure, water quality, fish, and macroinvertebrates have been pervasive, and I hypothesized that dense hydrilla stands would also impact vertebrate predation on resident macroinvertebrates, although predation effects would likely be mediated by bed position. During 2003 and 2004, I conducted exclosure experiments in the Atchafalaya River Basin with artificial substrates to test for variations in hydrilla bed macroinvertebrate communities caused by predation, plant architecture, and bed position. To determine invertebrates …
Biologically Inspired Learning System, Patrick Mcdowell
Biologically Inspired Learning System, Patrick Mcdowell
LSU Doctoral Dissertations
Learning Systems used on robots require either a-priori knowledge in the form of models, rules of thumb or databases or require that robot to physically execute multitudes of trial solutions. The first requirement limits the robot’s ability to operate in unstructured changing environments, and the second limits the robot’s service life and resources. In this research a generalized approach to learning was developed through a series of algorithms that can be used for construction of behaviors that are able to cope with unstructured environments through adaptation of both internal parameters and system structure as a result of a goal based …
Separation And In Situ Catalytic Testing Of A Dirhodium Tetraphosphine Catalyst, Bobby Lloyd Barker
Separation And In Situ Catalytic Testing Of A Dirhodium Tetraphosphine Catalyst, Bobby Lloyd Barker
LSU Doctoral Dissertations
Attempts to study the asymmetric hydroformylation abilities of [rac-Rh2(nbd)2(et,ph-P4)](BF4)2 were made through the separation of the enantiomers of et,ph-P4 using a chiral HPLC column. Efforts were also made to optimize the NiCl2 separation chemistry for the methyl analogue of et,ph-P4 for use in asymmetric hydroformylation. A study of hydroformylation of olefins using [rac-Rh2(nbd)2(et,ph-P4)](BF4)2 in ionic liquids was also performed, leading directly to the important (and unexpected) effect of increased hydrogen pressure on [rac-Rh2(nbd)2(et,ph-P4)](BF4)2 in the acetone/water system to …
Fluvial Evolution Of The Garonne River, France: Integrating Field Data With Numerical Simulations, Robin Rene Lancaster
Fluvial Evolution Of The Garonne River, France: Integrating Field Data With Numerical Simulations, Robin Rene Lancaster
LSU Master's Theses
The Garonne River of southwestern France presents a unique opportunity to study the controls on long-term incision and terrace formation within a large-scale fluvial system. The Garonne heads in the Pyrenees, flows through the Aquitaine Basin, and discharges into Atlantic Ocean via the Gironde Estuary/Bay of Biscay. From field data, three terrace complexes were identified and traced for >251 km from the base of the Pyrenees to the onset of tidal influences. Each complex is separated from adjacent complexes by scarps >10 m and represent 10s to 100s kyrs during which time the river occupied a finite elevational range within …
Modern Interpretation Of Euclid's Theory Of Ratio And Proportion, Mark Robert Stecher
Modern Interpretation Of Euclid's Theory Of Ratio And Proportion, Mark Robert Stecher
LSU Master's Theses
Euclid’s Elements is the foundation for geometry. Book V of Euclid’s Elements, which is independent from the earlier books, focuses on multiples, ratios, and proportions. This paper presents a model of the conceptual content of Book V, but using carefully selected modern notation to represent Euclid’s ideas without changing them drastically. All of the propositions and proofs from Euclid have been restated using just enough modern language to make clear for a modern reader. We also present a modern theory that bears analogy, proposition by proposition, to Euclid’s theory, but uses rigorous modern methods of proof.
Synthetic Development And Application Of Compounds With Biological Relevance, Jeffery Caleb Clark
Synthetic Development And Application Of Compounds With Biological Relevance, Jeffery Caleb Clark
LSU Doctoral Dissertations
Nature has provided a vast number of compounds that have medicinal application. The use of these compounds provided by nature however, is limited by the amount of a specific compound that nature provides. The synthesis of these molecules and their derivatives provides an even greater number of compounds for biological screening. Various pyrroles, the heterocyclic building blocks of porphyrins, can be prepared synthetically over several steps. The implementation of carboranes on pyrrole rings intrinsically provides substrates that can be converted into porphyrins bearing carborane substituents. The condensation of these carboranylpyrroles with carboranylaldehydes provides carboranylporphyrins bearing a higher order of carborane …
Fracture Behavior Of Wood Plastic Composite (Wpc), Gi Young Jeong
Fracture Behavior Of Wood Plastic Composite (Wpc), Gi Young Jeong
LSU Master's Theses
In this study, the effect of notch length on impact strength and fracture toughness was examined to exploit the use of wood plastic composite (WPC) as structural materials. Impact and fracture toughness test methods and estimation procedures were carried out. To evaluate the impact strength of WPC, five different notch sizes with two different fiber orientations on the load head were prepared. In terms of fracture mechanics, notch length was converted to stress concentration factor and the relationship between stress concentration factor and impact strength was determined. Fracture surface of impact specimens was investigated to evaluate the fracture mechanism of …
Evaluation Of A Novel Method Of Predicting Estrogen Activity Of A Group Of Structurally Diverse Compounds, Daniel Consoer
Evaluation Of A Novel Method Of Predicting Estrogen Activity Of A Group Of Structurally Diverse Compounds, Daniel Consoer
LSU Master's Theses
The number of environmental chemicals found to have some level of endocrine activity has led to concern about the possible effects these compounds could have on human health and the health of other species, populations, and possibly whole ecosystems. The United States Environmental Protection Agency has been charged with testing a large number of these compounds, called endocrine-disrupting chemicals or hormonally active agents for hormonal activity. Limited testing resources have led to a call for alternate methods of screening, possibly for use in prioritizing this list to assist in efficient allocation of resources for further testing. This study describes a …
Shear Induced Orientation In Polymer-Clay Solutions And Their Influence On The Structure In Multilayered Films, Matthew Michael Malwitz
Shear Induced Orientation In Polymer-Clay Solutions And Their Influence On The Structure In Multilayered Films, Matthew Michael Malwitz
LSU Doctoral Dissertations
The influence of shear on viscoelastic solutions of poly(ethylene oxide) (PEO) and clay (Cloisite, CNA) was investigated by rheology and small angle neutron scattering (SANS) under shear. These measurements determined the shear-induced orientation of the clay and the polymer as well as their relaxation behavior after cessation of shear. Comparison of PEO-CNA solutions (~100 nm diameter platelets) to previously studied PEO-Laponite gels (~30 nm diameter platelets) found that the orientation of CNA platelets occurs at much lower shear rates. Additionally, the relaxation times were much longer for CNA platelets than for Laponite platelets. From these solutions and gels, multilayered nanocomposite …
Simulation Study For Wireless Sensor Networks And Load Sharing Routing Protocol To Increase Network Life And Connectivity, Ankur Suri
LSU Master's Theses
LSU SensorSimulator is a framework for simulating wireless sensor networks. It is a customizable and extendible simulator, which allows testing and analyzing software for wireless sensor networks. The users can subclass the framework classes and customize the behavior of various network layers. This subclassing gives a way to the developers an opportunity to analyze and investigate, phenomenological, networking, robustness and scaling issues, to explore arbitrary algorithms for distributed sensors, independent of hardware constraint. The results are compared against the simulation results for ns-2 for routing protocols Directed Diffusion and GEAR. Through the comparison of results for scalability, performance and memory …
Broadcast In Sparse Conversion Optical Networks Using Fewest Converters, Tong Yi
Broadcast In Sparse Conversion Optical Networks Using Fewest Converters, Tong Yi
LSU Doctoral Dissertations
Wavelengths and converters are shared by communication requests in optical networks. When a message goes through a node without a converter, the outgoing wavelength must be the same as the incoming one. This constraint can be removed if the node uses a converter. Hence, the usage of converters increases the utilization of wavelengths and allows more communication requests to succeed. Since converters are expensive, we consider sparse conversion networks, where only some specified nodes have converters. Moreover, since the usage of converters induces delays, we should minimize the use of available converters. The Converters Usage Problem (CUP) is to use …
Dynamical Systems With Time Delay, Norma Ortiz
Dynamical Systems With Time Delay, Norma Ortiz
LSU Doctoral Dissertations
In this dissertation, we study necessary conditions and weak invariance properties of dynamical systems with time delay. A number of results have been obtained recently that refine necessary conditions of optimal solutions for nonsmooth dynamical systems without time delay. In this dissertation, we examine the extension of some of these results to problems with time delay. In particular, we study the generalized problem of Bolza with the addition of delay in the state and velocity variables and refer to this problem as the Neutral Problem of Bolza. We consider the relationship between the generalized problem of Bolza with time delay …
Use Of Terraced Marsh Habitats By Estuarine Nekton In Southwestern Louisiana, Bryan Paul Gossman
Use Of Terraced Marsh Habitats By Estuarine Nekton In Southwestern Louisiana, Bryan Paul Gossman
LSU Master's Theses
A variety of techniques have been employed in attempts to mitigate the extensive wetland loss occurring in coastal Louisiana. Marsh terracing is a wetland restoration technique that has rapidly gained in popularity in recent years. Terraces are assumed to benefit coastal restoration by providing areas for emergent plant growth, reducing wave energies, and increasing edge habitat to support nekton communities. The objectives of this study were to: 1) determine the effect of marsh terraces on adjacent water quality and sediment characteristics, 2) compare nekton abundance, species richness, and diversity in edge and open water habitats within terraced and unterraced ponds, …
The Stereoselective Synthesis Of The Butyrolactone-Bridged [8-5-5] Tricyclic Ring Systems Of (+/-)-Asteriscanolide Via The Titanium-Mediated Hetero-Pauson-Khand Reaction, Mohamed G. Sherriff
The Stereoselective Synthesis Of The Butyrolactone-Bridged [8-5-5] Tricyclic Ring Systems Of (+/-)-Asteriscanolide Via The Titanium-Mediated Hetero-Pauson-Khand Reaction, Mohamed G. Sherriff
LSU Doctoral Dissertations
The stereoselective construction of the tricyclic ring system of asteriscanolide from cyclooctadiene has been achieved. The synthesis involves two main steps; the synthesis of the aldehyde precursor(5)and the titanium-mediated cabocyclization of 5 to make the three rings of 43 stereoselectively.
Synthesis, Characterization And Application Of Polymeric Surfactants In Micellar Electrokinetic Chromatography: Use Of Ionic Liquids As Modifiers, Simon M. Mwongela
Synthesis, Characterization And Application Of Polymeric Surfactants In Micellar Electrokinetic Chromatography: Use Of Ionic Liquids As Modifiers, Simon M. Mwongela
LSU Doctoral Dissertations
The goal of the research presented in this dissertation is to synthesize, characterize, and apply a novel chiral amino acid-based surfactant and achiral sulfate-based surfactants for the effective separations of chiral and achiral compounds in micellar electrokinetic chromatography (MEKC). The first part of this research involves novel synthesis, characterization, and application of polysodium oleyl-L-leucyl-valinate (poly-L-SOLV) for the separation of chiral compounds in MEKC. Surface tensiometry, proton nuclear magnetic resonance, infrared spectroscopy, densitometry and analytical ultracentrifugation were used as the characterization techniques. Optimal MEKC separating conditions were established by varying surfactant concentration, buffer concentration and pH, applied voltage, and capillary temperature. …
Boundary Effects On Non-Equilibrium Localized Structures In Spatially Extended Systems, Aniruddha Yadav
Boundary Effects On Non-Equilibrium Localized Structures In Spatially Extended Systems, Aniruddha Yadav
LSU Doctoral Dissertations
A study of the effects of system boundaries on bistable front propagation in nonequilibrium reaction-diffusion systems is presented. Two model partial differential equations displaying bistable fronts, with distinct experimental motivations and mathematical structure, are examined in detail utilizing simulations and perturbation techniques. We see that propagating fronts in both models bounce, trap, pin, or oscillate at the boundary, contingent on the imposed boundary condition, initial front speed and distance from the boundary. The similarities in front boundary interactions in these two models is traced to the fact that they display the same front instability (Ising-Bloch bifurcation) that controls the speed …
Error Estimates For Stabilized Approximation Methods For Semigroups, Sarah Campbell Mcallister
Error Estimates For Stabilized Approximation Methods For Semigroups, Sarah Campbell Mcallister
LSU Doctoral Dissertations
In this work we analyze error estimates for rational approximation methods, and their stabilizations, for strongly continuous semigroups. Chapter 1 consists of a brief survey of time discretization methods for semigroups. In Chapter 2, we demonstrate a new method for obtaining convergent approximations in the absence of stability for strongly continuous semigroups with arbitrary initial data. In Section 2.2, we state the stabilization result in more general form and show that this method can be used to improve known error estimates by a magnitude of up to one half for smooth initial data. In Section 2.3, we give concrete examples …
Morphologic And Stratigraphic Evolution Of The Antarctic Peninsula, Pacific Margin, Jason Henry Holloman
Morphologic And Stratigraphic Evolution Of The Antarctic Peninsula, Pacific Margin, Jason Henry Holloman
LSU Master's Theses
Rebesco et al. (1998) proposed a general depositional model that relates sediment drift evolution on the Antarctic Peninsula Pacific-margin continental rise to glacial processes on the continental shelf. In their model, terrigenous sediment was directly delivered to the rise and contributed to the construction of large sediment drifts when grounded ice extended to the shelf edge. In this scenario, large volumes of fluidized sediment by-passed the margin at the mouth of ice streams (i.e., fast flowing ice), whereas prograding slopes were constructed on those portions of the shelf margin between major ice streams. This model relies heavily on the modern …