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2005

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Improvements In Groundwater Flow Modeling Through The Integration Of Resistivity Logs And Hydraulic Conductivity And The Use Of Variogram Uncertainty, Asheka Rahman Jan 2005

Improvements In Groundwater Flow Modeling Through The Integration Of Resistivity Logs And Hydraulic Conductivity And The Use Of Variogram Uncertainty, Asheka Rahman

LSU Doctoral Dissertations

This study developed a coregionalized model to estimate hydraulic conductivity using spatial cross correlation between hydraulic conductivity and borehole geophysical data (a transform of the formation factor). An experimental pseudocross variogram is used instead of a cross variogram because data are not collocated. Experimental variogram uncertainty is investigated using confidence intervals for the experimental variogram calculated assuming variogram sills are lognormally distributed. These intervals are used for sensitivity modeling using kriging, cokriging, simulation and cosimulation. The hydraulic conductivity fields generated by kriging, cokriging, simulation, and cosimulation are then used in a high-resolution groundwater model created using telescopic mesh refinement (TMR) …

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Zeta Functions Of Finite Graphs, Debra Czarneski Jan 2005

Zeta Functions Of Finite Graphs, Debra Czarneski

LSU Doctoral Dissertations

Ihara introduced the zeta function of a finite graph in 1966 in the context of p-adic matrix groups. The idea was generalized to all finite graphs in 1989 by Hashimoto. We will introduce the zeta function from both perspectives and show the equivalence of both forms. We will discuss several properties of finite graphs that are determined by the zeta function and show by counterexample several properties of finite graphs that are not determined by the zeta function. We will also discuss the relationship between the zeta function of a finite graph and the spectrum of a finite graph.

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Using Ground Penetrating Radar, Light Detection And Ranging, Geodetic Leveling, And Area Hydrogeology To Study The Baton Rouge And Scotlandville Faults, East Baton Rouge Parish, La, Angela Mooi Thomas Jan 2005

Using Ground Penetrating Radar, Light Detection And Ranging, Geodetic Leveling, And Area Hydrogeology To Study The Baton Rouge And Scotlandville Faults, East Baton Rouge Parish, La, Angela Mooi Thomas

LSU Master's Theses

East Baton Rouge Parish, Louisiana, is situated on at least two faults, the Baton Rouge Fault and the Denham Springs-Scotlandville Fault. These faults have surface expressions in the form of escarpments and damage to man-made structures. The purpose of this thesis is to study these faults in the shallow subsurface, in climate and soils found in Louisiana, and to study their ability to block fluid flow and whether groundwater withdrawal influences the amount and rate of subsidence along these faults. Techniques used to gather field data or to research and compile previously acquired data for this thesis includes: Ground Penetrating …

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Energy-Rate Based Mac Protocol For Wireless Sensor Networks And Key Pre-Distribution Schemes, Ramaraju Kalidindi Jan 2005

Energy-Rate Based Mac Protocol For Wireless Sensor Networks And Key Pre-Distribution Schemes, Ramaraju Kalidindi

LSU Master's Theses

Sensor networks are typically unattended because of their deployment in hazardous, hostile or remote environments. This makes the problem of conserving energy at individual sensor nodes challenging. S-MAC and PAMAS are two MAC protocols which periodically put nodes (selected at random) to sleep in order to achieve energy savings. Unlike these protocols, we propose an approach in which node duty cycles (i.e sleep and wake schedules) are based on their criticality. A distributed algorithm is used to find sets of winners and losers, who are then assigned appropriate slots in our TDMA based MAC protocol. We introduce the concept of …

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Identifying Asphalt Construction As A Point Source Emitter Of Volatile Organic Compounds Near The Louisiana State University Ozone Monitoring Station, Sean Jason Kice Jan 2005

Identifying Asphalt Construction As A Point Source Emitter Of Volatile Organic Compounds Near The Louisiana State University Ozone Monitoring Station, Sean Jason Kice

LSU Master's Theses

The EPA has classified Baton Rouge as a non-attainment area for ozone pollution for many years. Since then Photochemical Assessment Monitoring Stations (PAMS) and other ozone monitoring stations around the metropolitan area have monitored for ozone, NOx, and more than 50 volatile organic compounds (VOCs) which are considered precursors to ozone pollution. Traditionally, automobile engines and industrial plants and refineries have been blamed as major point sources for VOC emissions and the ozone pollution they cause. This research focuses on another possible point source for failing ozone levels at one of the ozone monitoring stations located on the campus of …

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The Genetics Of Speciation By Reinforcement, Daniel Ortiz-Barrientos Jan 2005

The Genetics Of Speciation By Reinforcement, Daniel Ortiz-Barrientos

LSU Doctoral Dissertations

Reinforcement occurs when natural selection strengthens behavioral discrimination to prevent costly interpopulation matings, such as when matings produce sterile hybrids. This evolutionary process can complete speciation, thereby providing a direct link between Darwin’s theory of natural selection and the origin of new species. My dissertation presents the first study on the genetics of reinforcement. This study is framed in a conceptual body that explains how genomic architecture, selection and recombination, interact to facilitate divergence in the presence of gene flow. In addition, in my dissertation I produced a dense recombination map for D. pseudoobscura, which together with the genome sequence …

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Parallel Molecular Dynamics Simulations Of Pressure-Induced Structural Transformations In Cadmium Selenide Nanocrystals, Nicholas Jabari Ouma Lee Jan 2005

Parallel Molecular Dynamics Simulations Of Pressure-Induced Structural Transformations In Cadmium Selenide Nanocrystals, Nicholas Jabari Ouma Lee

LSU Doctoral Dissertations

Parallel molecular dynamics (MD) simulations are performed to investigate pressure-induced solid-to-solid structural phase transformations in cadmium selenide (CdSe) nanorods. The effects of the size and shape of nanorods on different aspects of structural phase transformations are studied. Simulations are based on interatomic potentials validated extensively by experiments. Simulations range from 105 to 106 atoms. These simulations are enabled by highly scalable algorithms executed on massively parallel Beowulf computing architectures. Pressure-induced structural transformations are studied using a hydrostatic pressure medium simulated by atoms interacting via Lennard-Jones potential. Four single-crystal CdSe nanorods, each 44Å in diameter but varying in length, in the …

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Visualization Based On Interactive Clipping: Application To Confocal Data, Gaurav Khanduja Jan 2005

Visualization Based On Interactive Clipping: Application To Confocal Data, Gaurav Khanduja

LSU Master's Theses

We have explored how clipping can be exploited in an interactive manner to visualize massive three-dimensional datasets. In essence, the proposed interactive clipping approach involves the dynamic adjustment of the clipping plane to expose any cross-section of the volume data and subsequent adjustment of the clipped surface to the best view position using a combination of rotation and translation. The thesis describes the design, implementation and application of our interactive-clipping-based visualization system. The implementation is done with OpenGL and C++, thus resulting in a highly portable and flexible system. For illustration, two types of scientific datasets, confocal data of a …

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Stm And Arpes Studies Of Epitaxial Multilayer Ag On Cu(110) And Ni(110), Weichang Zhao Jan 2005

Stm And Arpes Studies Of Epitaxial Multilayer Ag On Cu(110) And Ni(110), Weichang Zhao

LSU Doctoral Dissertations

Ag nanostructures of multilayer coverages (< 30 monolayers) epitaxially self-assembled on Cu(110) and Ni(110) have been explored by scanning tunneling microscopy (STM), angle-resolved photoelectron emission spectroscopy (ARPES), and low energy electron diffraction (LEED). We have studied varied nanostructure morphologies self-assembled depending on different deposition/annealing processes and coverages, their atomic structures, growth behaviors and mechanisms, and the electronic structures of nanowires. At nominal coverages of 1.2 ML < ¦È < ~10 ML, there are two epitaxial structures on Cu(110) and Ni(110). One is a Ag(110) multilayer film, which has a superstructure with lateral periodic units of eight and three/four substrate lattice constants along [¯110] and along [001] respectively. Another is that of Ag(110) nanowires surrounded by pseudohexagonal Ag(111) monolayer. The Ag(110) nanowires are triangular in cross section. The two side surfaces are faceted and the long axis is atomically straight along [¯110]. Typical lengths are within the range of 100 ~ 5000 Å, widths 70 ~ 300 Å, side slopes 10 ~ 30º, and heights 5 ~ 60 Å. The Ag nanowires present extraordinary anisotropy with observed aspect ratios (length:width) of up to 20:1. The Ag(110) nanowires are in-registry with the substrate along [001], but not along [¯110]. At coverages of ~ 10 ML < ¦È < ~25 ML, there also exist two different nanostructures, the nanowires and a Ag(110) atomically-flat film with some pits as deep as down to the substrate and a one-dimensional quasiperiodic superstructure along [001]. There are two basic separations of the superstructural stripes: one is three lattices wide (~11 Å) and the other is two lattices wide (~7 Å). Both of nanostructures are stable at temperature up to at least 200 ¡ãC and not inter-transformable. The growth of the nanowires is driven by the elastic strain mechanism, but the growth of the atomically-flat film is driven by electronic growth mechanism originated from the electron quantum confinement in the vertical direction of the film. The ARPES of the nanowires shows dispersion in the vertical and the [¯110] directions, but no dispersion in the [001] direction because of the limited width (~ 200 Å).

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The Effectiveness Of Student Support Services At A Research Extensive University In The South, Eric Lyle Penalber Jan 2005

The Effectiveness Of Student Support Services At A Research Extensive University In The South, Eric Lyle Penalber

LSU Doctoral Dissertations

The primary purpose of this study was to determine the influence of level of participation in services provided by the Student Support Services (SSS) Program on the grade point average, retention, and the six-year graduation rate of first-time entering freshmen who also entered the SSS program at a research extensive university in the South. Participants in the study were one hundred, fifty-two (152) SSS students who entered this university in the fall of 1996 and fall of 1997. Tinto’s (1987) longitudinal model of institutional departure was used as the conceptual framework for this study. Services provided by the SSS program …

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Effects Of Adding Sediment To A Fresh Water Thin Mat Floating Marsh, Kate Carpenter Jan 2005

Effects Of Adding Sediment To A Fresh Water Thin Mat Floating Marsh, Kate Carpenter

LSU Master's Theses

Floating marshes are wetlands of emergent vascular vegetation which have a significant mat of live and dead roots, decomposing and dead organic material, and mineral sediments. This mat moves vertically as ambient water levels rise and fall. These marshes have unique hydrology in that overland sheet flow is reduced or eliminated leaving no inorganic sediment input, but there is extensive belowground water exchange. The effect of significant sediment introduction into wetlands with floating marshes is unknown. The purpose of this study was to observe the marsh mat response to Mississippi River sediment addition and measure species composition change and growth …

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A Study Of Distributed Clustering Of Vector Time Series On The Grid By Task Farming, Arun B. Nayar Jan 2005

A Study Of Distributed Clustering Of Vector Time Series On The Grid By Task Farming, Arun B. Nayar

LSU Master's Theses

Traditional data mining methods were limited by availability of computing resources like network bandwidth, storage space and processing power. These algorithms were developed to work around this problem by looking at a small cross-section of the whole data available. However since a major chunk of the data is kept out, the predictions were generally inaccurate and missed out on significant features that was part of the data. Today with resources growing at almost the same pace as data, it is possible to rethink mining algorithms to work on distributed resources and essentially distributed data. Distributed data mining thus holds great …

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Physically Based Multiscale-Viscoplastic Model For Metals And Steel Alloys: Theory And Computation, Farid H. Abed Jan 2005

Physically Based Multiscale-Viscoplastic Model For Metals And Steel Alloys: Theory And Computation, Farid H. Abed

LSU Doctoral Dissertations

The main requirement of large deformation problems such as high-speed machining, impact, and various primarily metal forming, is to develop constitutive relations which are widely applicable and capable of accounting for complex paths of deformation. Achieving such desirable goals for material like metals and steel alloys involves a comprehensive study of their microstructures and experimental observations under different loading conditions. In general, metal structures display a strong rate- and temperature-dependence when deformed non-uniformly into the inelastic range. This effect has important implications for an increasing number of applications in structural and engineering mechanics. The mechanical behavior of these applications cannot …

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Platform Recruited Reef Fish, Phase I: Do Platforms Provide Habitat That Increase The Survival Of Juvenile Reef Fishes?, Lauren Kay Nowling Jan 2005

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 …

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Nekton Utilization Of Black Mangrove (Avicennia Germinans) And Smooth Cordgrass (Spartina Alterniflora) Sites In Southwestern Caminada Bay, Louisiana, Melanie Christine Caudill Jan 2005

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 …

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Automatic Segmentation Of Magnetic Resonance Images Of The Brain, Kirk V. N. Spence Jan 2005

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 …

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Characterization Of Aged Polymer Modified Asphalt Cements For Recycling Purposes, Codrin Daranga Jan 2005

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 …

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Medical Image Enhancement, Alina Monica Trifas Jan 2005

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 …

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Enantioselective Syntheses And Chemical Investigations Of Plant-Derived Bioactive Volatile Compounds, Anne Marie Sauer Jan 2005

Enantioselective Syntheses And Chemical Investigations Of Plant-Derived Bioactive Volatile Compounds, Anne Marie Sauer

LSU Doctoral Dissertations

Research, inspired by nature, provides ample opportunity for discovery, ingenuity, and creative endeavor. For these reasons, the work and accomplishments presented herein focus on the total syntheses and related investigations of a variety of natural product derivatives, specifically (+)-nootkatone and jasmone. While the former consists of several independent projects: (a) an enantioselective synthetic route to (+)-nootkatone and derivatives, (b) examination of the valencane ring system, (c) determination of the absolute configuration of (+)-nootkatone, and (d) rearrangements of various sesquiterpenoid derivatives; the latter focuses on the construction ofƒndelta, epsilon-unsaturated carbonyl compounds, hetero Pauson-Khand substrates, via [3,3]-sigmatropic rearrangements.

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Cognitive Memory Effects On Non-Linear Video-Based Learning, Katherine Renee Comeaux Jan 2005

Cognitive Memory Effects On Non-Linear Video-Based Learning, Katherine Renee Comeaux

LSU Master's Theses

During an informative learning process, information, material, facts and ideas are typically conveyed in a linear arrangement. Individuals are frequently distracted during this process with their attention being diverted to an interruption (Internet, phone call, etc). When presented with any new information, the mind evolves through problem solving and evaluation procedures. The way in which that information is processed and perceived depends on: (a) original presentation (b) examination of material and (c) an individualistic measurement of success. However, when faced with an interruption, the person is forced to deal with non-linear arrangement of information. This research investigates nonlinear presentation or …

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Virtual Strings For Closed Curves With Multiple Components And Filamentations For Virtual Links, William Schellhorn Jan 2005

Virtual Strings For Closed Curves With Multiple Components And Filamentations For Virtual Links, William Schellhorn

LSU Doctoral Dissertations

The theory of filaments on oriented chord diagrams can be used to detect some non-classical virtual knots. We extend existing filament techniques to virtual links with more than one component and give examples of virtual links that these techniques can detect as non-classical. Given a signed Gauss word underlying an oriented chord diagram, we describe how to construct a finite sequence of integers that encodes all of the filament information for the diagram. We also introduce a square array of integers called a MIN-square that summarizes the filament information about all of the signed Gauss words having a given Gauss …

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Synthesis Of Symmetric And Asymmetric Water-Soluble Porphyrin Derivatives, Caroline Owendi Ongayi Jan 2005

Synthesis Of Symmetric And Asymmetric Water-Soluble Porphyrin Derivatives, Caroline Owendi Ongayi

LSU Doctoral Dissertations

Novel symmetric and asymmetric water-soluble tetrabenzoporphyrin are synthesized in relatively good yields. These compounds are synthesized by the condensation of butanopyrrole with several aldehydes that contain masked water solubilizing groups followed by metal insertion, oxidation and demetallation and deprotection of the masked solubilizing groups. The biological evaluation (in vitro and in vivo) studies are described in addition to the photophysical evaluations of the corresponding compounds. A novel versatile route to the syntheses of novel free-bases and metallo-benzoylbiliverdin is discussed. The treatment of metal free-dodecasubstituted porphyrin with sodium nitrite and trifluoroacetic acid at room temperature in the presence of oxygen affords …

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Effects Of Body Size On Goose Behavior: Lesser Snow Goose And Ross's Goose, Jon Einar Jonsson Jan 2005

Effects Of Body Size On Goose Behavior: Lesser Snow Goose And Ross's Goose, Jon Einar Jonsson

LSU Doctoral Dissertations

Body size is highly variable among geese, both at intra- and interspecific levels. Interspecific variation in several behaviors has been attributed to differences in body size in geese: incubation constancy, tendency to maintain family units, and time spent foraging. Body size has important physiological implications for birds, mostly because mass-specific metabolic rate is greater for birds of smaller mass. The Body-size Hypothesis predicts that smaller species deplete their energy reserves at relatively faster rates than do larger species. Hypotheses and conclusions concerning effects of body size on waterfowl behavior often are based on comparisons of species that confront different climates, …

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Remote Power Delivery For Hybrid Integrated Bio-Implantable Electrical Stimulation System, Venkat Reddy Gaddam Jan 2005

Remote Power Delivery For Hybrid Integrated Bio-Implantable Electrical Stimulation System, Venkat Reddy Gaddam

LSU Master's Theses

Bio-implantable devices such as heart pacers, gastric pacers and drug-delivery systems require power for carrying out their intended functions. These devices are usually powered through a battery implanted with the system or are wired to an external power source. In this work, a remote power delivery system (RPDS) is considered as a means to charge rechargeable batteries that power a Bio-implanted Electrical Stimulation System (BESS). A loosely coupled inductive power transmitter and receiver system has been designed to recharge batteries for a bio-implanted gastric pacer. The transmitter coil is periodically worn around the waist. The receiver coil, rechargeable batteries, battery-charging …

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Mathematical Models For Estimating Volatile Chemical Emissions From Dredging Operations, Kenneth Alexander Fountain Jan 2005

Mathematical Models For Estimating Volatile Chemical Emissions From Dredging Operations, Kenneth Alexander Fountain

LSU Master's Theses

Dredging operations have been a common remediation for contaminated sediment in an effort to reduce the harmful impact on the environment. The objective of this research was to create models used for estimating chemical release to air from remediating the Indiana Harbor and Canal (IHC) as three separate dredging operations; the Dredge Site, Exposed DM CDF, and Ponded CDF. The evaporative flux estimations are based on a two-resistance mass transport path inclusive of both the molecular diffusion in porous media and interfacial airside mass transport resistances. Several chemodynamic algorithms were used in calculating key transport parameters. Laboratory tests were performed …

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Sensorsimulator: Simulation Framework For Sensor Networks, Cariappa D. Mallanda Jan 2005

Sensorsimulator: Simulation Framework For Sensor Networks, Cariappa D. Mallanda

LSU Master's Theses

Wireless sensor networks have the potential to become significant subsystems of engineering applications. Before relegating important and safety-critical tasks to such subsystems, it is necessary to understand the dynamic behavior of these subsystems in simulation environments. There is an urgent need to develop a simulation platform that is useful to explore both the networking issues and the distributed computing aspects of wireless sensor networks. Current approaches to simulating wireless sensor networks largely focus on the networking issues. These approaches use well-known network simulation tools that are often difficult to extend to explore distributed computing issues. Discrete-event simulation is a trusted …

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Naturally-Derived Porphyrin And Chlorin Photosensitizers For Photodynamic Therapy, Jodie Angela Hargus Jan 2005

Naturally-Derived Porphyrin And Chlorin Photosensitizers For Photodynamic Therapy, Jodie Angela Hargus

LSU Master's Theses

In oncologic applications of photodynamic therapy (PDT), the discriminating localization of porphyrin-type compounds in solid tumors is exploited for the selective ablation of neoplastic tissue with minimal destruction and irritation to normal tissue. PDT is a locoregional, binary cancer therapy in which a photosensitizer—light-activated drug—absorbs light of an appropriate wavelength and excites to the singlet state. This photosensitizer in the excited singlet state can undergo an internal transition to the excited triplet state, a relatively long-lived and high-energy species that transfers its excess energy to molecular oxygen. Molecular oxygen subsequently excites from the stable triplet state to the highly reactive …

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Restoration Success Of Backfilling Canals In Coastal Louisiana Marshes, Joseph Baustian Jan 2005

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 …

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Infrared And X-Ray Spectroscopic Studies Of The Copper(Ii) Oxide Mediated Reactions Of Chlorinated Aromatic Precursors To Pcdd/F, Steven L. Alderman Jan 2005

Infrared And X-Ray Spectroscopic Studies Of The Copper(Ii) Oxide Mediated Reactions Of Chlorinated Aromatic Precursors To Pcdd/F, Steven L. Alderman

LSU Doctoral Dissertations

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) are toxic compounds produced in combustion systems such as incinerators, and their emissions are an important environmental issue. Chlorinated phenols and benzenes form PCDD/F through heterogeneous reactions following adsorption onto fly-ash surfaces. Current research implicates transition metals in promoting formation of phenoxyl radicals that react to form PCDD/F, although this has not been studied extensively. This objective of this work is to better understand PCDD/F formation from chlorinated aromatic precursors. Using 2 chlorophenol as a model PCDD/F precursor and silica as a fly-ash surrogate, time-dependent chemisorption of 2 chlorophenol onto silica was studied in situ …

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Host-Parasite Cophylogeny And Rates Of Evolution In Two Rodent-Louse Assemblages, Jessica E. Light Jan 2005

Host-Parasite Cophylogeny And Rates Of Evolution In Two Rodent-Louse Assemblages, Jessica E. Light

LSU Doctoral Dissertations

Studies of cophylogeny greatly increase understanding of associations between hosts and their parasites. This study uses molecular data to test the hypothesis that members of two rodent families (Geomyidae and Heteromyidae) and their associated lice (Geomydoecus and Fahrenholzia, respectively) show a statistically significant pattern of cophylogeny. Both host groups are generally solitary organisms and both louse groups are obligate ectoparasites, often exhibiting extreme degrees of host specificity. This intimate and potentially long-term association likely has resulted in coevolutionary adaptations and counter adaptations on the part of both symbiotic partners. Phylogenetic analysis of chewing lice (Geomydoecus) reveals two major clades corresponding …

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