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2002

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A Variable Response Time Lag Module For Car Following Models Using Fuzzy Set Theory, Yilmaz Hatipkarasulu Jan 2002

A Variable Response Time Lag Module For Car Following Models Using Fuzzy Set Theory, Yilmaz Hatipkarasulu

LSU Doctoral Dissertations

Since the 1950s, car following phenomena have been studied and analyzed, resulting in various models and algorithms. In general, the car following process has been defined as a stimulus-response relationship in which the driver of the following vehicle reacts to the actions of the lead vehicle after a time lag. One of the fundamental assumptions that underlie car following theory is that the driver response time lag is always a constant value for the driver at all times, regardless of level of detail of the model. Assumption of a constant time lag value introduces a number of broad assumptions however, …

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Data Mining And Knowledge Discovery: A Guided Approach Base On Monotone Boolean Functions, Vetle Ingvald Torvik Jan 2002

Data Mining And Knowledge Discovery: A Guided Approach Base On Monotone Boolean Functions, Vetle Ingvald Torvik

LSU Doctoral Dissertations

This dissertation deals with an important problem in Data Mining and Knowledge Discovery (DM & KD), and Information Technology (IT) in general. It addresses the problem of efficiently learning monotone Boolean functions via membership queries to oracles. The monotone Boolean function can be thought of as a phenomenon, such as breast cancer or a computer crash, together with a set of predictor variables. The oracle can be thought of as an entity that knows the underlying monotone Boolean function, and provides a Boolean response to each query. In practice, it may take the shape of a human expert, or it …

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Evaluation Of Bacillus Thuringiensis Transgenic Field Corn For Management Of Louisiana Corn Pests, Boris A. Castro Jan 2002

Evaluation Of Bacillus Thuringiensis Transgenic Field Corn For Management Of Louisiana Corn Pests, Boris A. Castro

LSU Doctoral Dissertations

Efficacy of Bt corn hybrids expressing an insecticidal delta-endotoxin through different transformation events was evaluated in Louisiana. Efficacy levels were determined for southwestern corn borer (SWCB), Diatraea grandiosella Dyar; sugarcane borer (SCB), Diatraea saccharalis (F.); corn earworm (CEW), Helicoverpa zea (Boddie); and fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith). Insect (neonates and third instars) susceptibility was evaluated on Bt and non-Bt corn plants (V6 and R1 stages) in field plots and plant tissue in laboratory studies. Bt corn hybrids with MON810 and CBH351 transformation events sustained significantly (P < 0.05) less injury caused by SWCB, SCB, and FAW during infestations at mid-whorl stage. SWCB, SCB, and CEW infestations during silking stage were significantly reduced in Bt hybrids with the MON810 event. However, CEW infestations …

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High Resolution Modeling Of Transport In Porous Media, Guangli Liu Jan 2002

High Resolution Modeling Of Transport In Porous Media, Guangli Liu

LSU Doctoral Dissertations

This dissertation presents research on the pore-level modeling of transport in porous media. The focus of this work is on high-resolution modeling, a rigorous approach that represents detailed geometry and first-principle physics at the streamline scale. Three major topics are presented in this dissertation: an efficient approach for solving Stokes flow in essentially arbitrary disordered porous media, high-resolution versus network simulations of dispersion phenomena, and a stochastic model for solving interfacial mass transfer from source spheres in porous media. First an approach was developed for solving the Stokes flow problem in a comparatively large, very heterogeneous two-dimensional porous media with …

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Fabricating Microfluidic Devices In Polymers For Bioanalytica Applications, Sean M. Ford Jan 2002

Fabricating Microfluidic Devices In Polymers For Bioanalytica Applications, Sean M. Ford

LSU Doctoral Dissertations

The research presented in this document focuses on the fabrication, characterization and application of microfluidic systems fabricated in poly(methyl methacrylate) (PMMA) with the emphasis focused on the fabrication processing steps. Microfluidic devices were produced in PMMA using X-ray lithography. The fabrication methods investigated were sacrificial mask, polyimide membrane mask and embossing techniques. PMMA microfluidic devices fabricated using X-ray lithography were characterized using scanning electron microscopy (SEM) and optical microscopy, while analytical techniques such as electroosmotic flow determination, separations, and fluorescent microscopy were used to characterize fluid transport in these devices. A novel method for the heat annealing of PMMA to …

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Adoption Of Best Management Practices In The Louisiana Dairy Industry, Noro C. Rahelizatovo Jan 2002

Adoption Of Best Management Practices In The Louisiana Dairy Industry, Noro C. Rahelizatovo

LSU Doctoral Dissertations

The traditional view of the agricultural community as a good steward of the environment has been challenged by increasing concerns about the complex relationship between agricultural production activities and environmental quality. Agriculture provides a large range of products to satisfy human needs. It has also been singled out as major source of water pollution. Largely improved surface water quality has been assessed in the U.S. since the enactment of the Clean Water Act. However, efforts to reduce water pollution continue, targeting discharges from identifiable sources of water pollution and diffused discharges from nonpoint sources. Agricultural producers are encouraged to voluntarily …

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Boundary Effects On Multiplication Noise In Thin Heterostructure Avalanche Photodiodes: Theory And Experiment [Al/Sub 0.6/Ga/Sub 0.4/As/Gaas], Majeed M. Hayat, Oh-Hyun Kwon, Shuling Wang, Joe C. Campbell, Bahaa E.A. Saleh, Malvin Carl Teich Jan 2002

Boundary Effects On Multiplication Noise In Thin Heterostructure Avalanche Photodiodes: Theory And Experiment [Al/Sub 0.6/Ga/Sub 0.4/As/Gaas], Majeed M. Hayat, Oh-Hyun Kwon, Shuling Wang, Joe C. Campbell, Bahaa E.A. Saleh, Malvin Carl Teich

Electrical and Computer Engineering Faculty Research and Publications

The history-dependent recurrence theory for multiplication noise in avalanche photodiodes (APDs), developed by Hayat et al., is generalized to include inter-layer boundary effects in heterostructure APDs with multilayer multiplication regions. These boundary effects include the initial energy of injected carriers as well as bandgap-transition effects within a multilayer multiplication region. It is shown that the excess noise factor can be significantly reduced if the avalanche process is initiated with an energetic carrier, in which case the initial energy serves to reduce the initial dead space associated with the injected carrier. An excess noise factor reduction up to 40% below the …

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Mechanism Of The Nicofe Ternary Alloy Deposition, Yun Zhuang Jan 2002

Mechanism Of The Nicofe Ternary Alloy Deposition, Yun Zhuang

LSU Doctoral Dissertations

Electrodeposited NiCoFe ternary alloys are of interest for their magnetic and thermophysical properties. The reaction rates and resulting composition and current efficiency are often determined empirically, due to a lack of understanding of the electrodeposition mechanism and coupled mass transport. Therefore, the effects of electrolyte concentration, bulk pH and solution agitation are studied over a wide range of applied current densities to investigate the interrelated behavior of the partial reaction rates. The Fe rate during alloy deposition is independent of Co2+ and Fe2+ bulk concentrations, but is enhanced compared with its single metal rate. Both catalytic and inhibiting effects are …

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Gain-Bandwidth Characteristics Of Thin Avalanche Photodiodes, Majeed M. Hayat, Oh-Hyun Kwon, Yi Pan, Paul P. Sotirelis, Joe C. Campbell, Bahaa E.A. Saleh, Malvin Carl Teich Jan 2002

Gain-Bandwidth Characteristics Of Thin Avalanche Photodiodes, Majeed M. Hayat, Oh-Hyun Kwon, Yi Pan, Paul P. Sotirelis, Joe C. Campbell, Bahaa E.A. Saleh, Malvin Carl Teich

Electrical and Computer Engineering Faculty Research and Publications

The frequency-response characteristics of avalanche photodiodes (APDs) with thin multiplication layers are investigated by means of a recurrence technique that incorporates the history dependence of ionization coefficients. In addition, to characterize the autocorrelation function of the impulse response, new recurrence equations are derived and solved using a parallel computer. The mean frequency response and the gain-bandwidth product are computed and a simple model for the dependence of the gain-bandwidth product on the multiplication-layer width is set forth for GaAs, InP, Al/sub 0.2/Ga/sub 0.8/As, and In/sub 0.52/Al/sub 0.48/As APDs. It is shown that the dead-space effect leads to a reduction (up …

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Improvement Of Resonant Harmonic Filter Effectiveness In The Presence Of Distribution Voltage Distortion, Herbert L. Ginn Jan 2002

Improvement Of Resonant Harmonic Filter Effectiveness In The Presence Of Distribution Voltage Distortion, Herbert L. Ginn

LSU Doctoral Dissertations

Resonant harmonic filters (RHFs), are the most common devices installed in distribution systems for reducing distortion caused by harmonic generating loads. When such filters are applied in systems with a distorted distribution voltage their effectiveness may decline drastically. This dissertation explores the causes of degradation of RHFs effectiveness and suggests methods of their improvement both by optimization algorithms and by modification of the filter structure. An optimization based design method is developed for the conventional RHF. It takes into consideration the interaction of the filter with the distribution system and provides a filter which gives the maximum effectiveness with respect …

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Capillary And Microdevice Electrophoretic Tools For Genetic Analyses: Heteroduplex Analysis For Tuberculosis Drug Susceptibility And Ligase Detection Reaction For Colorectal Cancer Detection, Gloria Thomas Jan 2002

Capillary And Microdevice Electrophoretic Tools For Genetic Analyses: Heteroduplex Analysis For Tuberculosis Drug Susceptibility And Ligase Detection Reaction For Colorectal Cancer Detection, Gloria Thomas

LSU Doctoral Dissertations

The traditional format of electrophoresis, the slab gel, is quickly being replaced by capillary and microdevice platforms, which offer improvements in cost, resolution, speed, quantitation and automation in genetic analyses. These techniques also employ a variety of separation matrices while the slab gel is limited to agarose and polyacrylamide. The research presented here explores the use of these electrophoretic formats for the detection of single nucleotide mutations using two genetic models associated with human disease. Slab gel based heteroduplex analysis (HDA), a popular mutation scanning method, uses a specially designed universal heteroduplex generator (UHG) containing controlled variation to enhance the …

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Retention And Movement Of Reactive Chemicals In Soils, Hongxia Zhu Jan 2002

Retention And Movement Of Reactive Chemicals In Soils, Hongxia Zhu

LSU Doctoral Dissertations

Adsorption-desorption and transport behavior of pesticides are important processes that influence the amount retained by the soil and that which is susceptible to runoff or movement within the soil profile. Kinetic batch experiments were used to study the adsorption-desorption behavior of metolachlor (a non-ionic herbicide) and deltamethrin (a pyrethroid insectcide) in soils, and atrazine (a triazine) in sugarcane mulch residue. Miscible displacement experiments under steady flow conditions were carried out to examine the mobility of these pesticides in soils. Metolachlor adsorption and desorption by Sharkey clay soil(Very-fine, smectitic, thermic Chromic Epiaquerts) and Commerce silty loam soil (Fine-silty, mixed, superactive, nonacid, …

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Perceptions Of Active Graduate Faculty At A Research Extensive University Regarding Electronic Submission Of Theses And Dissertations (Etds), Ursula Irene Anna Goldsmith Jan 2002

Perceptions Of Active Graduate Faculty At A Research Extensive University Regarding Electronic Submission Of Theses And Dissertations (Etds), Ursula Irene Anna Goldsmith

LSU Doctoral Dissertations

This study investigates and explores faculty perceptions toward Electronic Theses and Dissertations (ETDs) during the implementation of ETDs at a university located in the southern portion the United States. Louisiana State University and Agriculture and Mechanical College (LSU) is the flagship university for the state of Louisiana and one of only 25 universities nationwide holding both land-grant and sea-grant status. The Carnegie Foundation for the Advancement of Teaching classified LSU as Doctoral/Research Universities-Extensive. Chapter 1 provides the rationale for this study, the importance of higher education, the importance and role of the faculty advisor in graduate education as influencing the …

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Three-Dimensional Micromachined On-Chip Inductors For High Frequency Applications, Nimit Chomnawang Jan 2002

Three-Dimensional Micromachined On-Chip Inductors For High Frequency Applications, Nimit Chomnawang

LSU Doctoral Dissertations

Demands for wireless communication are ever-escalating for consumer and military communication applications. The requirements of portability, more functionality and lower cost have been driving forces toward smaller, more sophisticated and flexible wireless devices with lower power consumption. To meet these requirements, monolithically integrated passive inductors with high Q-factors and high self-resonant frequencies are desirable. Q-factor and self-resonant frequency of an inductor are significantly degraded at high frequencies due to conductor ohmic loss, magnetically induced eddy current in the conductive substrate, and lower self-resonant frequency from capacitance between conductive substrate and conductors.
In this dissertation, novel three-dimensional arch-like solenoid and dome-shaped …

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Fast Scalable Visualization Techniques For Interactive Billion-Particle Walkthrough, Xinlian Liu Jan 2002

Fast Scalable Visualization Techniques For Interactive Billion-Particle Walkthrough, Xinlian Liu

LSU Doctoral Dissertations

This research develops a comprehensive framework for interactive walkthrough involving one billion particles in an immersive virtual environment to enable interrogative visualization of large atomistic simulation data. As a mixture of scientific and engineering approaches, the framework is based on four key techniques: adaptive data compression based on space-filling curves, octree-based visibility and occlusion culling, predictive caching based on machine learning, and scalable data reduction based on parallel and distributed processing. In terms of parallel rendering, this system combines functional parallelism, data parallelism, and temporal parallelism to improve interactivity. The visualization framework will be applicable not only to material simulation, …

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The Effects Of Local Hydrodynamics On Mass Transfer In Disordered Porous Media, Gang Guo Jan 2002

The Effects Of Local Hydrodynamics On Mass Transfer In Disordered Porous Media, Gang Guo

LSU Doctoral Dissertations

Interfacial mass transfer in disordered media was studied experimentally and numerically. The dissolution of solid benzoic acid spheres in packed columns showed the existence of spatial variations in mass transfer coefficients in monodisperse and polydisperse packings at the same overall Peclet number. The concept of a local Peclet number (single-particle average) was introduced to quantify the effect of local hydrodynamics on local mass transfer. Correlations between Sherwood number and Peclet number having the form Shi=A·(xiPe)m were used to quantify data from various sites in each packing. These experiments also showed that the exponent m varies …

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Outcrop To Subsurface Stratigraphy Of The Pennsylvanian Hermosa Group Southern Paradox Basin U.S.A., Alan Lee Brown Jan 2002

Outcrop To Subsurface Stratigraphy Of The Pennsylvanian Hermosa Group Southern Paradox Basin U.S.A., Alan Lee Brown

LSU Doctoral Dissertations

Pennsylvanian (Desmoinesian) sedimentary rocks within the Paradox Basin Four Corners area of the western United States afford a unique opportunity to study the development of sedimentary successions in a complex marine to nonmarine depositional setting. The close association of thick intervals of nonmarine fan-delta facies adjacent to and in time equivalent position to marine carbonate-evaporite facies suggests complex relationships between the factors affecting deposition. Development of an effective scheme to differentiate the depositional signatures from within these sedimentary successions is the primary goal of this study. To achieve this goal, two objectives were pursued. The first was to calibrate the …

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Characterization Of Alligator, Ostrich And Emu Skins And Comparisons To Traditional Leathers, Terri M. Von Hoven Jan 2002

Characterization Of Alligator, Ostrich And Emu Skins And Comparisons To Traditional Leathers, Terri M. Von Hoven

LSU Doctoral Dissertations

Exotic skins and leathers have enjoyed a recent resurgence, as current fashion magazines illustrate. Louisiana would like to increase its niche in the exotic skins market by increasing alligator, ostrich and emu skin usage, mainly by inspiring designers to incorporate them into their repertoire. The possibilities are endless from apparel and trim to upholstery and other home furnishings to accessories; Louisiana exotic skins have significant market potential. In order to assist in these traditional textile applications, characterization of the various skin properties needs to be completed. The research was carried out in three stages. For the preliminary research, one emu …

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Bollworm (Lepidoptera: Noctuidae) Ecology On Genetically Engineered Bollgard And Bollgard Ii Cottons, Jeffrey Gore Jan 2002

Bollworm (Lepidoptera: Noctuidae) Ecology On Genetically Engineered Bollgard And Bollgard Ii Cottons, Jeffrey Gore

LSU Doctoral Dissertations

The ecology of bollworms, Helicoverpa zea (Boddie), on Bollgard and Bollgard II cottons, Gossypium hirsutum L., was studied in field and laboratory experiments. Neonate bollworm larvae were placed on selected components of cotton squares and flowers from non-Bollgard, Bollgard, and Bollgard II cotton varieties. Larval survival was higher on flower anthers and square anthers than on other floral parts for each cultivar. Bollworm survival was lowest on all Bollgard II floral structures. To evaluate larval behavior on Bollgard cotton, first instar bollworms were placed on terminals of non-flowering and flowering cotton plants. Larvae were recovered lower on Bollgard cotton than …

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Experimental Evaluation Of Control Fluid Fallback During Off-Bottom Well Control In Vertical And Deviated Wells, Fernando Sebastian Flores-Avila Jan 2002

Experimental Evaluation Of Control Fluid Fallback During Off-Bottom Well Control In Vertical And Deviated Wells, Fernando Sebastian Flores-Avila

LSU Doctoral Dissertations

This study measured the liquid fallback during simulated blowout conditions. The purpose of the study was to establish a basis for developing a procedure for controlling blowouts that relies on the accumulation of liquid kill fluid injected while the well continues to flow. The results from experiments performed with air, water, 10.5 ppg and 12.0 ppg mud in an experimental 48 ft flow loop at 0°, 20°, 40°, 60° and 75° deviation angles from the vertical, as well as results from full-scale experiments performed with natural gas and water based drilling fluid in a vertical 2787-foot deep research well, are …

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Simulation And Optimization Of A Crossdocking Operation In A Just-In-Time Environment, Karina Hauser Jan 2002

Simulation And Optimization Of A Crossdocking Operation In A Just-In-Time Environment, Karina Hauser

University of Kentucky Doctoral Dissertations

In an ideal Just-in-Time (JIT) production environment, parts should be delivered to the workstationsat the exact time they are needed and in the exact quantity required. In reality, formost components/subassemblies this is neither practical nor economical. In this study, thematerial flow of the crossdocking operation at the Toyota Motor Manufacturing plant inGeorgetown, KY (TMMK) is simulated and analyzed.At the Georgetown plant between 80 and 120 trucks are unloaded every day, with approximately1300 different parts being handled in the crossdocking area. The crossdocking areaconsists of 12 lanes, each lane corresponding to one section of the assembly line. Whereassome pallets contain parts …

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Strain Control Of Piezoelectric Materials Using An Applied Electron Flux, Philip Clark Hadinata Jan 2002

Strain Control Of Piezoelectric Materials Using An Applied Electron Flux, Philip Clark Hadinata

University of Kentucky Doctoral Dissertations

This dissertation examines the response of piezoelectric material strain to electron flux influence. A plate of PZT5h is prepared as the specimen. The positive electrode is removed, and the negative electrode is connected to a power amplifier. Sixteen strain gages are attached as the strain sensor. The specimen is placed in a vacuum chamber, then the positive side is illuminated by electron beam. The characteristic of the static strain response is predicted by deriving the equation strain/deflection of the plate. Two methods are used, the Electro-Mechanical Equations and numerical analysis using Finite Element Method. The settings of the electron gun …

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Structure And Function Analysis Of Par-4, Nadia M. El-Guendy Jan 2002

Structure And Function Analysis Of Par-4, Nadia M. El-Guendy

University of Kentucky Doctoral Dissertations

Par-4 is a leucine zipper domain protein that induces apoptosis on its own in certain cancer cells and in Ras-transformed cells, but not in normal or immortalized cells. Par-4 induces apoptosis by activation of the Fas death receptor pathway and co-parallel inhibition of NF-B transcription activity. Cells that are resistant to apoptosis by Par-4 alone, however, are greatly sensitized by Par-4 to the action of other pro-apoptotic insults such as growth factor withdrawal, TNF, ionizing radiation, intracellular calcium elevation, or those involved in neuronal degeneration such as Alzheimer's, Parkinson's, Huntington's and Stroke. Previous studies have suggested that the apoptosis-sensitization potential …

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An Xps Study Of The Thermal Degradation Of Polystyrene-Clay Nanocomposites, Jianqi Wang, Jianxin Du, Jin Zhu, Charles A. Wilkie Jan 2002

An Xps Study Of The Thermal Degradation Of Polystyrene-Clay Nanocomposites, Jianqi Wang, Jianxin Du, Jin Zhu, Charles A. Wilkie

Chemistry Faculty Research and Publications

X-ray photoelectron spectroscopy, XPS, has been used to examine several polystyrene-clay nanocomposites. The accumulation of oxygen, from the almuniosilicate, on the surface of the polymer was observed, along with the loss of carbon. This confirms that the barrier properties of the clay provide a mechanism by which nanocomposite formation can enhance the fire retardancy of the polymers. No difference is detected depending upon the extent of exfoliation or intercalation of the nanocomposite. #2002 Elsevier Science Ltd. All rights reserved.

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Three-Dimensional Structure Of The Complexin/Snare Complex, Xiaocheng Chen, Diana R. Tomchick, Evgenii L. Kovrigin, Demet Araç, Mischa Machius, Thomas C. Südhof, Josep Rizo Jan 2002

Three-Dimensional Structure Of The Complexin/Snare Complex, Xiaocheng Chen, Diana R. Tomchick, Evgenii L. Kovrigin, Demet Araç, Mischa Machius, Thomas C. Südhof, Josep Rizo

Chemistry Faculty Research and Publications

During neurotransmitter release, the neuronal SNARE proteins synaptobrevin/VAMP, syntaxin, and SNAP-25 form a four-helix bundle, the SNARE complex, that pulls the synaptic vesicle and plasma membranes together possibly causing membrane fusion. Complexin binds tightly to the SNARE complex and is essential for efficient Ca2+-evoked neurotransmitter release. A combined X-ray and TROSY-based NMR study now reveals the atomic structure of the complexin/SNARE complex. Complexin binds in an antiparallel α-helical conformation to the groove between the synaptobrevin and syntaxin helices. This interaction stabilizes the interface between these two helices, which bears the repulsive forces between the apposed membranes. These results …

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Overexpression And Divalent Metal Binding Properties Of The Methionyl Aminopeptidase From Pyrococcus Furiosus, Lu Meng, Shane Ruebush, Ventris M. D'Souza, Alicja J. Copik, Susumu Tsunasawa, Richard C. Holz Jan 2002

Overexpression And Divalent Metal Binding Properties Of The Methionyl Aminopeptidase From Pyrococcus Furiosus, Lu Meng, Shane Ruebush, Ventris M. D'Souza, Alicja J. Copik, Susumu Tsunasawa, Richard C. Holz

Chemistry Faculty Research and Publications

The gene encoding for the methionyl aminopeptidase from the hyperthermophilic archaeon Pyrococcus furiosus (PfMetAP-II; EC 3.4.11.18) has been inserted into a pET 27b(+) vector and overexpressed in Escherichia coli. The new expression system resulted in a 5-fold increase in purified enzyme obtained from a 5 L fermentor growth. The as-purified PfMetAP-II enzyme, to which no exogenous metal ions or EDTA was added, was found to have 1.2 equiv of zinc and 0.1 equiv of iron present by ICP-AES analysis. This enzyme had a specific activity of 5 units/mg, a 60-fold decrease from the fully loaded Fe(II) …

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Communication Characterizing Successful Long Distance Marriages, Andrea Towers Scott Jan 2002

Communication Characterizing Successful Long Distance Marriages, Andrea Towers Scott

LSU Doctoral Dissertations

The current study seeks to explore the communication in successful career-induced long distance marriages. Elements examined are relational dialectics, relationship satisfaction, communication satisfaction, feelings of (mis)understanding, couple types, relationship sustenance, imagined interactions, and social support. The current study has three primary contributions: 1) the quantitative exploration of a communication in a growing marital framework, 2) the successful quantification of dialectics, and 3) the overall support for studying long distance marriages. The current study reports data collected from 92 individuals in non-military career-induced long distance marriages. All participants completed an 18-page questionnaire consisting of quantitative measures for the variables listed above, …

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Numerical Studies Of Reactive Polymer Flows In Porous Materials, Honggao Liu Jan 2002

Numerical Studies Of Reactive Polymer Flows In Porous Materials, Honggao Liu

LSU Doctoral Dissertations

This dissertation presents a new numerical model of reactive polymer flow in heterogeneous porous media. A moment representation of the log-normal polymer molecular weight distribution is used to model polymer as a multi-component species. Three leading moments are used to simulate the polymer transport and reaction processes in a two-dimensional porous medium. A new operator splitting technique that allows the moment equations for polymerization to be incorporated into a finite-difference transport model is developed. The novelty of this approach is the use of two different dependent variables (for the transport versus reaction parts of the problem). It is significant from …

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Solute Transport In Layered And Heterogeneous Soils, Liuzong Zhou Jan 2002

Solute Transport In Layered And Heterogeneous Soils, Liuzong Zhou

LSU Doctoral Dissertations

Better understanding of transport of dissolved chemicals in soils and aquifers is important to evaluate and remediate contaminated soils and aquifers. Because of the nature of heterogeneity of field porous media, studies on transport processes in non-homogeneous media are necessary. In this study, transport of solutes in layered and heterogeneous media was investigated using numerical approximations. For layered soils, transport properties were assumed homogeneous within individual layers but different between layers. For heterogeneous systems, either a time-dependent or distance-dependent dispersivity was considered to represent the effects of heterogeneity. In a series of simulations of transport in two-layered soils, we found …

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Extraction Of Physically-Realistic Pore Network Properties From Three-Dimensional Synchrotron Microtomography Images Of Unconsolidated Porous Media, Riyadh Ibrahim Al-Raoush Jan 2002

Extraction Of Physically-Realistic Pore Network Properties From Three-Dimensional Synchrotron Microtomography Images Of Unconsolidated Porous Media, Riyadh Ibrahim Al-Raoush

LSU Doctoral Dissertations

Algorithms were implemented to obtain high resolution three-dimensional images using synchrotron microtomography. Morphological algorithms were developed to extract physically-realistic pore-network structure from unconsolidated porous media systems imaged using synchrotron microtomography. The structure can be used to correlate pore-scale phenomena with the pore structure and can also be incorporated into a pore-network model to verify existing models, understand, or predict transport and flow processes and phenomena in complex porous media systems. The algorithms are based on the three-dimensional skeletonization of the pore space in the form of nodes connected to paths. Dilation algorithms were developed to generate inscribed spheres on the …

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