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Articles 2761 - 2790 of 3417

Full-Text Articles in Physical Sciences and Mathematics

The Impact Of Hypoxia On Mercury Methylation In Bottom Sediment Of Northern Gulf Of Mexico, Mei Huey Tan Jan 2006

The Impact Of Hypoxia On Mercury Methylation In Bottom Sediment Of Northern Gulf Of Mexico, Mei Huey Tan

LSU Master's Theses

Widespread concern has developed about high mercury content in fish in the Gulf of Mexico and adjacent estuaries and bays. Among the areas implicated as possible sources of the mercury that moves up the food chain from the methylmercury formed in sediments and anoxic waters is the seasonal hypoxic zone in the northern Gulf. This research was designed to determine if methylmercury formation is stimulated by the anaerobic sediment conditions accompanying the onset of summer hypoxia in the Gulf. Both field and laboratory studies were carried out. For the field study sediment samples were collected at three stations (i.e. C4, …


Index Future Pricing Under Imperfect Market And Stochastic Volatility, Wei-Hsien Li Jan 2006

Index Future Pricing Under Imperfect Market And Stochastic Volatility, Wei-Hsien Li

LSU Master's Theses

Financial markets in emerging countries are volatile and imperfect, so pricing model under traditional perfect-market frameset may not give reliable price of financial derivatives. The most famous pricing model for stock index future is the cost of carry model. The mis-pricing of cost of carry model inspires lots of following researches. Even transaction costs, dividends, stochastic interest rate, stochastic volatility, market imperfection, and other factors are considered, we still do not obtain a model price consistently better than cost of carry model. But these researches offer important insights, for example, the market needs time to mature and the more complex …


Study Of Reliable Data Communication In Wireless Sensor Networks, Ravilochan Shamanna Jan 2006

Study Of Reliable Data Communication In Wireless Sensor Networks, Ravilochan Shamanna

LSU Master's Theses

A distributed wireless sensor network consists of numerous tiny autonomous sensing nodes deployed across a wide geographical area. These sensor nodes self organize and establish radio communication links with the neighboring nodes to form multi-hop routing paths to the central base station. The dynamic and lossy nature of wireless communication poses several challenges in reliable transfer of data from the sensor nodes to the sink. There are several applications of sensor networks wherein the data collected by the sensors in the network are critical and hence have to be reliably transported to the sink. An example of such an application …


Two-Dimensional Penalized Signal Regression For Hand Written Digit Recognition, Qing Tang Jan 2006

Two-Dimensional Penalized Signal Regression For Hand Written Digit Recognition, Qing Tang

LSU Master's Theses

Many attempts have been made to achieve successful recognition of handwritten digits. We report our results of using statistical method on handwritten digit recognition. A digitized handwritten numeral can be represented by an image with grayscales. The image includes features that are mapped into two-dimensional space with row and column coordinates. Based on this structure, two-dimensional penalized signal logistic regression (PSR) is applied to the recognition of handwritten digits. The data set is taken from the USPS zip code database that contains 7219 training images and 2007 test images. All the images have been deslanted and normalized into 16 x …


Resource Recovery Of Coal Bed Methane Formation Water, Catherine Elizabeth Bishop Jan 2006

Resource Recovery Of Coal Bed Methane Formation Water, Catherine Elizabeth Bishop

LSU Master's Theses

During the excavation of natural gas, petroleum hydrocarbon-polluted brine water, termed production water, is drawn from the coal bed methane formations (CBMF) along with the natural gas product. The water is drawn out in vast amounts and re-injected into the CBMF. In the Greater Rocky Mountain Region (GRMR) where water supplies are dwindling, the remediation of CBMF production water has become a high priority for maintaining agriculture, residential development and industrial expansion. The overall objective of this research was to demonstrate in laboratory and field pilot studies the efficacious merging of Immobilized Microbe BioReactor (IMBR) technologies for biodegradation/mineralization of organics …


Computer-Aided Diagnostic Systems For Digital Mammograms, Nicholas Jabari Lee Jan 2006

Computer-Aided Diagnostic Systems For Digital Mammograms, Nicholas Jabari Lee

LSU Master's Theses

A computer-aided diagnostic (CAD) system that uses a unique shape-based classification scheme, the Ellipse-Closed Curve Fitting (ECCF) algorithm, is developed for digital mammogram image analysis. The system is developed to work as a post-processing extension to a previously developed CAD system that locates and segments mass lesions, or tumors, found in digital mammograms into separate images. The ECCF system is implemented in the MATLAB mathematical scripting language and is thus capable of running on multiple platforms. The ECCF algorithm detects edges in tumor images and casts them into closed curve functions. Parameters for an ellipse of best fit for a …


Swamp Tours In Louisiana Post Hurricane Katrina And Hurricane Rita, Dawn Schaffer Jan 2006

Swamp Tours In Louisiana Post Hurricane Katrina And Hurricane Rita, Dawn Schaffer

LSU Master's Theses

Hurricanes Katrina and Rita made landfall in southern Louisiana during August and September 2005, respectively. Prior to these storms swamp tours were a popular nature-based tourism experience that entertained visitors while teaching them about local flora, fauna, and culture. The number of swamp tour businesses in the state was slowly increasing. The purpose of this study was to determine how many swamp tours were operating after the hurricanes, what type of damage they sustained, and how they repaired their businesses. Differences between those tours that remained open after the hurricanes and those that closed were also examined. A 3-phase mail …


Study Of Reliable Data Communication In Wireless Sensor Networks, Ravilochan G. Shamanna Jan 2006

Study Of Reliable Data Communication In Wireless Sensor Networks, Ravilochan G. Shamanna

LSU Master's Theses

A distributed wireless sensor network consists of numerous tiny autonomous sensing nodes deployed across a wide geographical area. These sensor nodes self organize and establish radio communication links with the neighboring nodes to form multi-hop routing paths to the central base station. The dynamic and lossy nature of wireless communication poses several challenges in reliable transfer of data from the sensor nodes to the sink. There are several applications of sensor networks wherein the data collected by the sensors in the network are critical and hence have to be reliably transported to the sink. An example of such an application …


Effects Of Silvicultural Techniques And Landscape Management On Habitat Quality And Relative Abundance For Northern Bobwhites In A Pine Plantation Forest, Jason Douglas Burke Jan 2006

Effects Of Silvicultural Techniques And Landscape Management On Habitat Quality And Relative Abundance For Northern Bobwhites In A Pine Plantation Forest, Jason Douglas Burke

LSU Master's Theses

Pine plantation forests are increasing in scope across the southeastern United States, particularly Louisiana. These areas provide poor quality bobwhite brood-rearing habitats, and become increasingly degraded without periodic disturbance. Poor quality habitat conditions at a landscape-level scale usually results in reduced fall bobwhite body weights, creating low survival rates. We researched 4 understory vegetation management techniques (ie. mowing, no treatment, burn only, and imazapyr with burning) within pine plantations to evaluate their effects on vegetation composition and structure and on arthropod abundance and availability relative to bobwhite brooding habitat in 2002-2005. We used 1,155 human-imprinted bobwhite chicks to estimate foraging …


U.S. Demand For Certified Tropical Hardwood Products, Shadia Duery Jan 2006

U.S. Demand For Certified Tropical Hardwood Products, Shadia Duery

LSU Master's Theses

Tropical forests, which contain 50 percent of the planet's biodiversity, are threatened by deforestation and illegal logging. Forest certification was initiated initially as a s certification: forest management practices and chain of custody (CoC). The United States is the largest market for secondary, or value-added, tropical hardwood products (STHP) which influences forest management practices in supplier countries. In 2004, this study was conducted to measure the demand for certified products in the U.S. The objectives of the study were to identify characteristics of U.S. demand for secondary (value-added) tropical hardwood products and to understand market perceptions regarding certification of secondary …


Mcd And Magnetization Studies On Nifb/Nifz Minus Molybdenum Iron Protein From Azotobacter Vinelandii, Marcia S. Cotton Jan 2006

Mcd And Magnetization Studies On Nifb/Nifz Minus Molybdenum Iron Protein From Azotobacter Vinelandii, Marcia S. Cotton

LSU Master's Theses

This study reports a characterization of the iron-sulfur clusters of the MoFe protein expressed by the nifBnifZ deletion strain of A. vinelandii. VT-MCD spectroscopic and magnetization analysis of as-isolated ΔnifBΔnifZ MoFe protein were undertaken. VT-MCD spectra of as-isolated ΔnifBΔnifZ MoFe protein contains bands remarkably similar to those seen in as-isolated ΔnifH MoFe protein, assigned to arise from an [4Fe-4S]+ cluster. The low-temperature magnetization curve of as-isolated ΔnifBΔnifZ MoFe protein reveals the MCD spectra bands stem from an S = ½ spin system with diamagnetic contributions of some other species. As-isolated ΔnifBΔnifZ MoFe protein is compared with as-isolated ΔnifH MoFe …


Laboratory And Field Measurements Of Bioturbation By Macrofauna In A Coastal Setting, Skyler Neylon Jan 2006

Laboratory And Field Measurements Of Bioturbation By Macrofauna In A Coastal Setting, Skyler Neylon

LSU Master's Theses

Two ophiuroid species, Hemipholis elongata and Ophiophragmus spp. were studied in laboratory microcosms to elucidate patterns of sediment mixing for key bioturbators in the Mississippi Sound, Mississippi. The effects of bioturbation on artificially stratified sediments in microcosms were traced via time-series digital x-radiography. Preliminary results indicate that for three population densities of the brittle stars (comparable to field densities), a steady state volumetric bioturbation rate of 1-2 cm3/d is reached within two months of introduction to a fresh system. The preservation quotient, q, a fractional measure of preserved primary fabric, reached a minimum of 0.5 during the 16-week experiment. Maximum …


Breeding Waterbird Use Of Rice Fields In Southwestern Louisiana, Sergio Pierluissi Jan 2006

Breeding Waterbird Use Of Rice Fields In Southwestern Louisiana, Sergio Pierluissi

LSU Master's Theses

Rice fields are agricultural wetlands concentrated in several areas in the U.S., including southwestern Louisiana. Rice fields are flooded for much of the year and support thick emergent vegetation, potentially providing high-quality habitat for several species of breeding waterbirds. The objectives of this study were to (1) determine relative nest density, nest success, and habitat associations of breeding waterbirds in southwestern Louisiana rice fields and (2) determine the effectiveness of callback surveys as a monitoring tool. In the summers of 2004 and 2005, marsh bird surveys and nest searches were conducted in Cameron, Jefferson Davis, Vermilion, and Acadia Parishes in …


Using Elimination To Describe Maxwell Curves, Lucas P. Beverlin Jan 2006

Using Elimination To Describe Maxwell Curves, Lucas P. Beverlin

LSU Master's Theses

Cartesian ovals are curves in the plane that have been studied for hundreds of years. A Cartesian oval is the set of points whose distances from two fixed points called foci satisfy the property that a linear combination of these distances is a fixed constant. These ovals are a special case of what we call Maxwell curves. A Maxwell curve is the set of points with the property that a specific weighted sum of the distances to n foci is constant. We shall describe these curves geometrically. We will then examine Maxwell curves with two foci and a special case …


Security In Heterogeneous Wireless Networks, Vijay Bulusu Jan 2006

Security In Heterogeneous Wireless Networks, Vijay Bulusu

LSU Master's Theses

The proliferation of a range of wireless devices, from the cheap low power resource starved sensor nodes to the ubiquitous cell phones and PDA's has resulted in their use in many applications. Due to their inherent broadcast nature Security and Privacy in wireless networks is harder than the wired networks. Along with the traditional security requirements like confidentiality, integrity and non-repudiation new requirements like privacy and anonymity are important in wireless networks. These factors combined with the fact that nodes in a wireless network may have different resource availabilities and trust levels makes security in wireless networks extremely challenging. The …


Characterization Of The Dependency Across Foreign Exchange Markets Using Copulas, Ryan Coelho Jan 2006

Characterization Of The Dependency Across Foreign Exchange Markets Using Copulas, Ryan Coelho

LSU Master's Theses

Though Pearson's correlation coefficient provides a convenient approach to measuring the dependency between two variables, in the last few years, there has been a significant amount of literature cautioning against the use of Pearson's correlation coefficient, as it does not remain invariant under monotone transformations of the underlying distribution functions. Since we are interested in examining the dependency pattern observed by the return on the Sterling Pound with that of the Japanese Yen, we will use the notion of a copula to approximate the joint density function between the daily returns on the Sterling Pound and the Japanese Yen. In …


Salt Marsh Restoration With Sediment-Slurry Amendments Following A Drought-Induced, Large-Scale Disturbance, Angela Marie Schrift Jan 2006

Salt Marsh Restoration With Sediment-Slurry Amendments Following A Drought-Induced, Large-Scale Disturbance, Angela Marie Schrift

LSU Master's Theses

A large-scale, drought-induced disturbance occurred in Louisiana during the spring and summer of 2000. Approximately 100,000 acres of Spartina dominated marshes died-back and turned brown. This die-off caused considerable concern because in the absence of recovery dieback marshes can transform to mudflats, which can subside leading to open ponds. The state of Louisiana is attempting to restore some of the dieback marshes through the addition of sediment-slurries. The sediment-slurry generated significantly different marsh elevations: high elevation (mean and 95 % confidence interval: 29, 26 to 32 cm above ambient marsh), medium elevation (21, 19 to 24 cm), low elevation (14, …


Effective Bootstrapping Of Peer-To Peer Networks Over Mobile Ad-Hoc Networks, Wei Ding Jan 2006

Effective Bootstrapping Of Peer-To Peer Networks Over Mobile Ad-Hoc Networks, Wei Ding

LSU Doctoral Dissertations

Mobile Ad-hoc Networks (MANETs) and Peer-to-Peer (P2P) networks are vigorous, revolutionary communication technologies in the 21st century. They lead the trend of decentralization. Decentralization will ultimately win clients over client/server model, because it gives ordinary network users more control, and stimulates their active participation. It is a determinant factor in shaping the future of networking. MANETs and P2P networks are very similar in nature. Both are dynamic, distributed. Both use multi-hop broadcast or multicast as major pattern of traffic. Both set up connection by self-organizing and maintain connection by self-healing. Embodying the slogan "networking without networks," both abandoned traditional client/server …


Petrological And Geochemical Investigations Of Deep Sea Turbidite Sands In The Pandora And Moresby Troughs: Source To Sink Papua New Guinea Focus Area, Luke Jeremiah Patterson Jan 2006

Petrological And Geochemical Investigations Of Deep Sea Turbidite Sands In The Pandora And Moresby Troughs: Source To Sink Papua New Guinea Focus Area, Luke Jeremiah Patterson

LSU Master's Theses

The Moresby and Pandora Troughs of the northern Coral Sea are components of the deep-sea depositional system that is the ultimate sink for the Source to Sink Papua New Guinea (PNG) Focus Area. Cores collected from the R/V Melville during March-April 2004 reveal marine volcaniclastic and terrigenous turbidites deposited in these troughs during the Quaternary. Constraining the spatial, temporal, and provenance characteristics for these terrigenous sands through mineralogical, chemical, and textural analysis is the primary focus of this study. All cores contain thinly-bedded sandy turbidite packages interlayered with hemipelagic marls and typical centimeter-to-meter-thick turbidite sequences. The Moresby Trough core JPC22 …


Genetic Stratigraphy And Geochronology Of Last Interglacial Shorelines On The Central Coast Of South Carolina, Russell Willis Jan 2006

Genetic Stratigraphy And Geochronology Of Last Interglacial Shorelines On The Central Coast Of South Carolina, Russell Willis

LSU Master's Theses

This study investigated the shallow subsurface of the Lower Coastal Plain of South Carolina in order to determine the sea-level history and stratigraphic architecture preserved within several emergent shoreline complexes. The absolute age of each shoreline complex was estimated using single-aliquot regenerative-dose (SAR) optically stimulated luminescence (OSL) techniques. The resulting geochronology was incorporated into a high-resolution stratigraphic framework defined by ground penetrating radar calibrated with deep sediment cores, many of which contain a complete sequence of highstand deposition. Three emergent barrier complexes were identified within the Lower Talbot, Pamlico, and Princess Anne terraces, and assigned to sea-level highstands during interglacial …


Integral Cohomology Of The Siegel Modular Variety Of Degree Two And Level Three, Mustafa Arslan Jan 2006

Integral Cohomology Of The Siegel Modular Variety Of Degree Two And Level Three, Mustafa Arslan

LSU Doctoral Dissertations

In this thesis work Deligne's spectral sequence Ep,qr with integer coefficients for the embedding of the Siegel modular variety of degree two and level three, A2(3) into its Igusa compactification, A2(3)*, is investigated. It is shown that E3 = E and this information is applied to compute the cohomology groups of A2(3) over the integers.


Ice Sheet Grounding Zone Deposits On Ross Sea Continental Shelf (Antarctica): Seismic Facies Analysis And P-Wave Reflectivity Attributes, Adeniyi Adewumi Saanumi Jan 2006

Ice Sheet Grounding Zone Deposits On Ross Sea Continental Shelf (Antarctica): Seismic Facies Analysis And P-Wave Reflectivity Attributes, Adeniyi Adewumi Saanumi

LSU Master's Theses

Subglacial till and overlying glaciomarine deposits are difficult to distinguish because the physical properties of subglacial till may vary depending on the drainage conditions of the rock directly beneath the ice sheet. Based on approximately 120 kilometers of multi-channel seismic data, detailed seismic facies analysis and amplitude variation with offset (AVO) analysis are carried out to examine the distribution of ice sheet grounding zone deposits on the continental shelf of the Northern Basin, Ross Sea (Antarctica) and infer the physical properties of interpreted subglacial till. Seismic facies analysis led to the differentiation of distinct sub-environments around a grounded ice sheet: …


Links Between Environmental Mercury, Special Education, And Autism In Louisiana, Jessica Rury Jan 2006

Links Between Environmental Mercury, Special Education, And Autism In Louisiana, Jessica Rury

LSU Master's Theses

The number of children born every year with neurological disorders is increasing and some of this increase may be attributed to mercury exposure. Pregnant women ingest contaminated fish, which transfers high mercury concentrations to the unborn fetus. This exposure may result in methyl mercury buildup in the brain of the unborn fetus. Symptoms ranging from minor to severe may be observed as special educational needs in school systems. These include learning disorders, developmental delays, and autism. Louisianans are especially susceptible to mercury contamination because fish and shellfish are a major portion of their cultural diet. This study, through the use …


Genetic Effects Influencing Salinity And Cold Tolerance In Tilapia, Alvaro M. Armas-Rosales Jan 2006

Genetic Effects Influencing Salinity And Cold Tolerance In Tilapia, Alvaro M. Armas-Rosales

LSU Master's Theses

Genetic effects influencing salinity tolerance (ST) and cold tolerance (CT) were evaluated in two full diallel mating designs using six tilapia varieties: Oreochromis aureus (BL), O. mossambicus (MO), O. niloticus (NI), O. niloticus crossbreds (RE), Mississippi commercial strain (MC) and Florida red tilapia (FL). Statistical analyses provided estimates of direct heterosis (hi), cross heterosis (hij), maternal effects (mi), line effects (li), reciprocal and specific reciprocal effects (rij and r**ij), and general and specific combining abilities (GCA and Sij). Analysis of genetic effects for ST indicated that FL …


Syntheses And Biological Evaluation Of Water Soluble Carboranylporphyrins For Application In Boron Neutron Capture Therapy, Vijay Gottumukkala Jan 2006

Syntheses And Biological Evaluation Of Water Soluble Carboranylporphyrins For Application In Boron Neutron Capture Therapy, Vijay Gottumukkala

LSU Doctoral Dissertations

The goal of the research presented in this dissertation is to develop novel water soluble carboranylporphyrins that can deliver therapeutic dosage of boron specifically to tumors for application in boron neutron capture therapy. In order to accomplish this goal novel water soluble tetra(nido-carboranyl)porphyrin and the octa(nido-carboranyl)porphyrin with high boron contents are synthesized by the condensation of the carborane substituted benzaldehyde with the pyrrole under acidic conditions. These porphyrins are made water soluble by the deboronation of the closo-carboranes to afford the corresponding amphiphilic nido-carborane cages. The low cytotoxicity, high cellular uptake and intracellular localization of these carboranylporphyrins in tumor cells …


Assessing The Potential Impact Of Microbes In The Edwards And Trinity Aquifers Of Central Texas, Kelli Willson Randall Jan 2006

Assessing The Potential Impact Of Microbes In The Edwards And Trinity Aquifers Of Central Texas, Kelli Willson Randall

LSU Master's Theses

The Edwards Aquifer in central Texas is one of the largest carbonate aquifers in the United States, supplying nearly two million people with water. The role of microorganisms in the development of deep carbonate aquifers has not been thoroughly investigated. The Edwards Aquifer is composed of a freshwater zone and a sulfidic, saline water zone. Down-well video surveys show an abundance of white filamentous and planktonic biomass floating in the water column, indicating that the saline water may serve as a habitat for microbes and provide a unique opportunity to investigate microbially enhanced deep subsurface karstification. A combination of geochemical …


Fabrication, Characterization And Properties Of Hiercchically Ordered Nanocomposites, Avinash Dundigalla Jan 2006

Fabrication, Characterization And Properties Of Hiercchically Ordered Nanocomposites, Avinash Dundigalla

LSU Doctoral Dissertations

The objectives of this research are to study the structure, morphology and properties of poly(ethylene-oxide) (PEO)-clay nanocomposites using various imaging techniques. Optical Microscopy, Scanning Electron Microscopy, Environmental Scanning Electron Microscopy and Atomic Force Microscopy are used to image structures on all length scales. Complementary scattering experiments are discussed along with preliminary differential scanning calorimetry and Fourier Transform Infrared spectroscopy results. In particular we investigated the multilayered structures of PEO-Laponite and PEO-Montmorillonite multilayered films made from solution. The shear orientation of a polymer-clay network in solution combined with simultaneous solvent evaporation leads to supramolecular multilayer formation in the film. The resulting …


Verification Of Direct Brachytherapy Dosimetry For A Single Seed Implant, Jabari Robinson Jan 2006

Verification Of Direct Brachytherapy Dosimetry For A Single Seed Implant, Jabari Robinson

LSU Master's Theses

A new technique using direct post-implant dosimetry, which does not depend explicitly on brachytherapy seed orientation or position, was explored for a prostate and a breast case. This technique, proposed by E Sajo and ML Williams (SW), uses trace amounts of positron emitters placed in the seed capsule and uses the positron emission tomography image in conjunction with a computed tomography image (PET-CT) to compute the therapeutic dose distribution in the patient. The SW technique could reduce errors in the post-implant dose computations associated with seed localization, seed shadowing and medium heterogeneity. Dose point kernels were obtained using Monte Carlo …


Reliability Of Determining Adults From Juvenile Ducks By Presence Or Absence Of Notched Tail Feathers In Various Species Of North American Ducks, Thomas Michael Siwarski Jan 2006

Reliability Of Determining Adults From Juvenile Ducks By Presence Or Absence Of Notched Tail Feathers In Various Species Of North American Ducks, Thomas Michael Siwarski

LSU Master's Theses

I estimated when juvenile tail molt occurs for several commonly harvested duck species, mallards (Anas platyrhynchos), northern pintails (A. acuta) (hereafter referred to as pintails), gadwalls (A. strepera), lesser scaup (Aythya affinis), and redheads (A. americana). Tests showed that aging mallards by notched tail feathers became unreliable the earliest (early September), followed closely by pintails (mid-late September), with gadwalls being the latest of the dabbling ducks to lose reliability in aging by notched tail feathers (late November). Lesser scaup and redheads retained their notched tail feathers throughout January and the completion of hunting season. Based on initial banding and band …


Effects Of Insectivorous Birds On Tree Growth In The Maurepas Swamp, David M. Fox Jan 2006

Effects Of Insectivorous Birds On Tree Growth In The Maurepas Swamp, David M. Fox

LSU Master's Theses

Coastal forests in Louisiana are in decline due to natural and human caused changes in the hydrology of the region. Baldcypress and water tupelo trees have been further stressed by caterpillar herbivory in recent decades. Regeneration of water tupelo is crucial for cavity creation for nesting habitat for secondary cavity nesting bird populations. Insectivorous birds have been shown to decrease insect-caused leaf damage on trees in other ecosystems. Two experiments examining effects of insectivorous birds on tree growth were conducted in degraded areas of the Maurepas Swamp in southeastern Louisiana. In the first experiment, nest boxes were added to study …