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Monte Carlo Studies Of The Critical Phenomena In Carbon Monoxide Oxidation., Bing Yu Jan 1992

Monte Carlo Studies Of The Critical Phenomena In Carbon Monoxide Oxidation., Bing Yu

LSU Historical Dissertations and Theses

It is well established that anisotropy does not affect the critical behavior of a system in thermodynamic equilibrium undergoing a second order phase transition. We study here an anisotropic kinetic model for heterogeneous catalysis which mimics the oxidation of CO on the (110) surface of a transition metal like Pd. In this model, the oxidation process occurs at an infinite reaction rate. We mapped out the phase diagram of possible steady states for various anisotropic reaction and absorption processes as a function of the O$\sb2$/CO adsorption rate and the CO diffusion rate. The phase diagram depends upon the amount of …

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The Role Of Bovine Herpesvirus-1 Glycoprotein Iii In Molecular Pathogenesis And Immunomodulation., Katherine Marie Byrne Jan 1992

The Role Of Bovine Herpesvirus-1 Glycoprotein Iii In Molecular Pathogenesis And Immunomodulation., Katherine Marie Byrne

LSU Historical Dissertations and Theses

Bovine herpesvirus-1 (BHV-1) is the pathogenic agent for infectious bovine rhinotracheitis. Current vaccines to protect against infection have serious disadvantages to producers and have been implicated in epizootic outbreaks. The virus has also been shown to cause suppression of the immune system. BHV-1 vaccines could be improved by identifying and genetically deleting those aspects of the virus responsible for immunosuppression and providing a marker within the genome which would distinguish the vaccine strain from wild types in the case of disease outbreaks. This study examined the role of gIII in viral infection and immunosuppression. This was accomplished by expressing full …

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Reasoning Using Biological Content: Relationships Among Evidence, Theory, And Interpretation., Catherine Lee Cummins Jan 1992

Reasoning Using Biological Content: Relationships Among Evidence, Theory, And Interpretation., Catherine Lee Cummins

LSU Historical Dissertations and Theses

Theoretical sampling was used to select 30 high school biology and college zoology students who examined a simulation involving island biogeography. The literature base for the study was scientific reasoning, problem solving, and prescientific conceptions. The research questions were answered using qualitative and quantitative methods. The first research question was: What number and what type of variables would be used to evaluate biological data? The students used 19 categories of variables, and the most frequently used were size, distance, and food. The second research question was: Will students use the controlling variables strategy in this reasoning task? Only four students …

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Genetics Of Stalk And Seed Quality Traits In Maize (Zea Mays L.) With Lfy Gene., Sridhar Dronavalli Jan 1992

Genetics Of Stalk And Seed Quality Traits In Maize (Zea Mays L.) With Lfy Gene., Sridhar Dronavalli

LSU Historical Dissertations and Theses

Parenchyma cell death (PCD) in stalk internodes of maize (Zea mays L.) is related to stalk rot. Spread of stalk rotting fungi is restricted by living parenchyma cells. A previously reported correlation coefficient of 0.70 between leaf midrib cell death (LMCD) and PCD indicated that selection for LMCD might result in low PCD, thus improving stalk quality. Inheritance of PCD and LMCD in maize possessing the leafy (Lfy) gene needs to be investigated. Experiments were conducted in three environments to estimate general (GCA) and specific combining ability (SCA) effects for PCD and LMCD via a diallel cross among seven Lfy …

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Wave-Forced Hydrogeology And Diagenesis, Tague Reef, St. Croix, U.S. Virgin Islands., Brian Leslie Carter Jan 1992

Wave-Forced Hydrogeology And Diagenesis, Tague Reef, St. Croix, U.S. Virgin Islands., Brian Leslie Carter

LSU Historical Dissertations and Theses

Wave driven pressure variations in reef porewater were used to investigate the physical processes that affect early marine carbonate cementation in a bank-barrier reef. Cores taken along a transect, and porewater geochemistry sampled from wells were used to characterize sedimentary and geochemical environments. The cores show an Acropora palmata framework with a patchily cemented sandy matrix composes the forereef and reef crest, with dominantly loose sediments in the backreef. Hydraulic conductivities are approximately 1 $\times$ 10$\sp{-4}$ m/s. The wave climate is moderate, with up to 75 % wave height attenuation across the reef crest. Porewater pressure variations correspond to surface …

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Impact Of The Preservice Field Experience In Foreign Language Teaching: A Study Of The Development Of Preservice Teachers' Perspectives In Foreign Language Teaching. (Volumes I And Ii)., Denise Egea-Kuehne Jan 1992

Impact Of The Preservice Field Experience In Foreign Language Teaching: A Study Of The Development Of Preservice Teachers' Perspectives In Foreign Language Teaching. (Volumes I And Ii)., Denise Egea-Kuehne

LSU Historical Dissertations and Theses

Within the broader issue of teacher education, the focus of this study is on one of the most neglected areas of inquiry in the field of foreign languages, the preservice field experience, and the development of student teachers' perspectives of foreign language teaching. The following questions were specifically addressed: (1) What perspectives of foreign language teaching do student teachers hold upon completion of their program of university courses? (2) Is there an alteration of student teachers' perspectives of foreign language teaching during their student teaching semester? (3) What factors appear to influence student teachers' perspectives of foreign language teaching during …

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Effects Of Hydrologic Alterations On The Vegetation And Soils Of Marshes In Southern Louisiana., Kathryn Marie Flynn Jan 1992

Effects Of Hydrologic Alterations On The Vegetation And Soils Of Marshes In Southern Louisiana., Kathryn Marie Flynn

LSU Historical Dissertations and Theses

Hydrology is the primary forcing function in wetlands. Therefore, alterations to hydrology, which can result from either natural or anthropogenic causes, can have dramatic effects on wetland structure and function. Structural marsh management, one type of anthropogenic alteration, employs levees and water control structures to reduce or reverse wetland loss and enhance the productivity of natural renewable resources. Its use is becoming increasingly popular in southern Louisiana as a solution to the problem of marsh deterioration despite the fact that very line comprehensive data is available on the effectiveness of this practice. Associated with the use of structural marsh management …

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The Development, Validation, And Application Of A Two-Tier Diagnostic Instrument To Detect Misconceptions In The Areas Of Force, Heat, Light And Electricity., Bobby Jo Franklin Jan 1992

The Development, Validation, And Application Of A Two-Tier Diagnostic Instrument To Detect Misconceptions In The Areas Of Force, Heat, Light And Electricity., Bobby Jo Franklin

LSU Historical Dissertations and Theses

The purpose of this study was to investigate the concepts prevalent among students in specific physical science related classes and to identify what classroom teachers would do when confronted with this knowledge. A 40 item instrument, Misconception Identification in Science Questionnaire (MISQ), was developed to identify certain concepts in the areas of force, heat, light, and electricity and administered to 509 students. Interviews were conducted with a stratified sampling of 27 students to validate the instrument. Six teachers were observed and interviewed to determine teacher opinion relative to test usefulness, diagnostic testing in general and other instructional factors. Quantitative and …

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Development Of Various Quantitative And Analytical Methods For The Analysis Of The Dynamics Of Fish Populations: An Application To The Spotted Seatrout Population In Coastal Louisiana., Thomas Earl Helser Jan 1992

Development Of Various Quantitative And Analytical Methods For The Analysis Of The Dynamics Of Fish Populations: An Application To The Spotted Seatrout Population In Coastal Louisiana., Thomas Earl Helser

LSU Historical Dissertations and Theses

Presented in this dissertation are analytical and quantitative methods developed for an experimental gillnet sampling program for the analysis of the dynamics of fish populations, illustrated here on Louisiana's spotted seatrout population. Chapter 1 presents a new method of estimating gillnet selectivity using a system of simultaneous equations and a non-linear iterative maximum likelihood approach. The model solution is a set of parameter estimates which mathematically describe the response surface of capture probabilities for fish of size-class j in mesh size i. As an extension to the nonlinear maximum likelihood gillnet selectivity model, Chapter 2 presents a second approach using …

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Chemical And Immunological Properties Of Polysaccharide Extracted From Vibrio Parahaemolyticus., Mina Jassemzadeh Izadjoo Jan 1992

Chemical And Immunological Properties Of Polysaccharide Extracted From Vibrio Parahaemolyticus., Mina Jassemzadeh Izadjoo

LSU Historical Dissertations and Theses

The capsular polysaccharide (CPS) of Vibrio parahaemolyticus was extracted from agar grown cells and purified by ethanol precipitation, hi-speed centrifugation and chromatography on Sepharose CL-4B and Detoxi columns. The CPS was found to be acidic when chromatographed on DEAE cellulose. The three constituting sugars were determined by gas-liquid chromatography to be glucose, galactose and fucose. The molecular weight of CPS is one million or greater and in its pure form appeared to be non-immunogenic for rabbits. A monoclonal antibody (Mab) reactive by ELISA to CPS was generated. The Mab agglutinated whole cell suspensions in the slide test. Latex beads armed …

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Genetic And Systematic Study Of Viviparus Georgianus (Lea), A Freshwater Snail Species Complex., Masaya Katoh Jan 1992

Genetic And Systematic Study Of Viviparus Georgianus (Lea), A Freshwater Snail Species Complex., Masaya Katoh

LSU Historical Dissertations and Theses

Genetic and morphological variation were studied in a brooding (ovoviviparous) and morphologically variable freshwater snail (Viviparus georgianus (Lea)) in the southeastern United States. Eleven populations were clustered into three genetically isolated, allopatric species characterized by 7 to 15 diagnostic loci out of the 38 loci examined. These allopatric species were an eastern species (in eastern and southern Florida), a western species (in the Florida panhandle), and a central species in the Ochlockonee River. Nei's standard genetic distances between species were large (0.23-0.52) compared to within-species distances (0.00-0.06). Moreover, genetic distances between the Ochlockonee River species and other species were larger …

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Control Of Phytoplankton Production In A Shallow, Turbid Estuary., Christopher J. Madden Jan 1992

Control Of Phytoplankton Production In A Shallow, Turbid Estuary., Christopher J. Madden

LSU Historical Dissertations and Theses

Water column primary production and chlorophyll were sampled between 1986-1991 in Fourleague Bay, LA, a shallow (1.5 m), river-dominated estuary that is extremely turbid (K$\sb{\rm D}$ = 4.44 m$\sp{-1}$). A high speed system for continuous flow-through sampling, Dataflow$\sp\copyright$, was developed to measure physicochemical variables and in vivo chlorophyll fluorescence at high temporal (1 s) and spatial (5 m) resolution from a small boat. Phytoplankton net primary production (NPP) was measured using an incubator which rotated bottles to prevent settling of the contents. NPP was found to be artificially increased by 10-83% at high light levels in non-rotated bottles when cells …

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Host Quality Of Baldcypress And Its Influence On Fruittree Leafroller, Archips Argyrospila (Walker) (Lepidoptera: Tortricidae), Performance In Forested Wetlands Of Louisiana., James R. Meeker Jan 1992

Host Quality Of Baldcypress And Its Influence On Fruittree Leafroller, Archips Argyrospila (Walker) (Lepidoptera: Tortricidae), Performance In Forested Wetlands Of Louisiana., James R. Meeker

LSU Historical Dissertations and Theses

Ecological relationships between the fruittree leafroller (FTLR), (Archips argyrospila (Walker)) and a new host, baldcypress (Taxodium distichum (L.)), were investigated in southern Louisiana where persistent annual defoliation over increasingly larger areas has occurred since 1983. Defoliation was observed to correspond with common types of baldcypress foliage morphology; designated as open and appressed. Pondcypress, Shumard oak and citrus foliage also were examined. The objectives were to: (1) determine the relative suitability/susceptibility of foliage types, and (2) quantify parameters of foliage quality possibly influencing FTLR performance. Levels of defoliation, egg mass counts, and laboratory bioassays of: initial survival, host preference, growth, feeding, …

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Diagnostic Techniques For Detection Of Permethrin-Resistant Soybean Loopers, Pseudoplusia Includens (Walker), Determination Of The Impact Of Insecticide Treatments On Age-Specific Mortality And Feeding Activity, And Estimation Of Field Control., Jeffrey Scott Mink Jan 1992

Diagnostic Techniques For Detection Of Permethrin-Resistant Soybean Loopers, Pseudoplusia Includens (Walker), Determination Of The Impact Of Insecticide Treatments On Age-Specific Mortality And Feeding Activity, And Estimation Of Field Control., Jeffrey Scott Mink

LSU Historical Dissertations and Theses

A glass vial bioassay was developed to detect permethrin resistance in soybean looper, Pseudoplusia includens (Walker), larvae. Third, fourth, fifth, and sixth instar soybean loopers from laboratory (susceptible) and field strains were exposed to several concentrations of permethrin in 20 ml glass vials. LC$\sb{50}$'s for third, fourth, and fifth instars from each field strain were not significantly different. A discriminating concentration of 0.5 $\mu$g permethrin per vial was identified for detection of permethrin resistance in soybean looper field populations. Field strains from cotton-soybean agroecosystems exhibited higher levels of resistance than strains from soybean-corn agroecosystems. The reliability of the vial bioassay …

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The Effect Of Threecornered Alfalfa Hopper Populations On Alfalfa Growth And The Development Of Host Plant Resistance Screening Techniques., Daniel John Moellenbeck Jan 1992

The Effect Of Threecornered Alfalfa Hopper Populations On Alfalfa Growth And The Development Of Host Plant Resistance Screening Techniques., Daniel John Moellenbeck

LSU Historical Dissertations and Theses

This dissertation research was designed with three main objectives: to evaluate the effects of threecornered alfalfa hopper, Spissistilus festinus (Say), feeding on alfalfa, Medicago sativa L., yield, regrowth, root carbohydrate composition, and disease incidence; to screen alfalfa cultivars for resistance to the threecornered alfalfa hopper and develop effective screening techniques; and to determine the mechanism(s) of this resistance. Greenhouse studies determined the effects of threecornered alfalfa hopper infestations on alfalfa growth and their relationship with Fusarium crown-rot. Significant interaction effects between insect population and the presence of Fusarium were found for number of harvestable stems and acid detergent fiber concentration. …

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Integrated Pest Management Studies Of The Cotton Aphid, Aphis Gossypii Glover., Patti Jane O'Brien Jan 1992

Integrated Pest Management Studies Of The Cotton Aphid, Aphis Gossypii Glover., Patti Jane O'Brien

LSU Historical Dissertations and Theses

Studies were conducted to characterize insecticide resistance and to document aspects of the basic biology of the cotton aphid, Aphis gossypii Glover, that were related to recommendations for integrated pest management. Laboratory, greenhouse, and field techniques were employed in these investigations. Significant levels of resistance were demonstrated to four recommended insecticide classes. Resistance appeared more stable over time for the organophosphate insecticide (chlorpyrifos) than for the organochlorine (endosulfan) and pyrethroid (bifenthrin) insecticide tested. The organophosphate resistance ratio of a clonal line of the cotton aphid was significant, but relatively low. Carboxylesterases, as studied by spectrophotometric and electrophoretic techniques, appeared involved …

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Analysis Of Protein Factors Involved In Transport Of The Precursor Of The Small Subunit Of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Into Intact Chloroplasts., Steven Mark Pomarico Jan 1992

Analysis Of Protein Factors Involved In Transport Of The Precursor Of The Small Subunit Of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Into Intact Chloroplasts., Steven Mark Pomarico

LSU Historical Dissertations and Theses

Two protein factors involved in the transport of precursor proteins into intact chloroplasts have been examined. The first of these was observed in experiments utilizing fusion proteins containing various lengths of wheat pS fused to CaM. Transport experiments with these fusion proteins demonstrated a requirement for transport of a pS/CaM fusion protein of a portion of mature S greater than 4 amino acids. Additionally, when the CaM portion of a fusion protein adopted a stable conformation by binding Ca$\sp{2+}$, a larger portion of mature S was needed for efficient transport. A second protein factor was examined using DIDS, and the …

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From Their Perspective: Issues Of Schooling And Family Culture Of Four African-American First Generation College Students., Neari Francois Warner Jan 1992

From Their Perspective: Issues Of Schooling And Family Culture Of Four African-American First Generation College Students., Neari Francois Warner

LSU Historical Dissertations and Theses

The diversity of students entering today's colleges and universities makes it increasingly important that educators, theorists and other scholars strive toward a fuller understanding of the life conditions of minority groups. This research is designed to provide insight into the processes, pressures and people that shape the lives of one particular minority group, the African American non-traditional, first generation college student. In this research, I examine the school and family experiences of four of these students in an attempt (1) to provide data that contribute to the refutation of the stereotypical images and myths that are so pervasively used to …

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Phylogenetic Systematics Of The Ulvophyceae (Chlorophyta) Based On Cladistic Analyses Of Ribosomal Rna Genes And Morphology., Frederick William Zechman Jan 1992

Phylogenetic Systematics Of The Ulvophyceae (Chlorophyta) Based On Cladistic Analyses Of Ribosomal Rna Genes And Morphology., Frederick William Zechman

LSU Historical Dissertations and Theses

Cladistic analyses of non-molecular and nuclear-encoded rRNA sequence data provided the basis for hypotheses of relationships for the green algal class Ulvophyceae. Non-molecular data rooted with Chara support hypotheses which group the Chlorophyceae and Pleurastrophyceae with ulotrichalean and ulvalean Ulvophyceae. Analyses of rRNA sequence data group the siphonous and siphonocladous Ulvophyceae (i.e. Caulerpales, Siphonocladales, and Dasycladales) with the Chlorophyceae and Pleurastrophyceae. Although hypotheses supported by these independent data sets are incongruent, they suggest that the Ulvophyceae is not monophyletic. Based on rRNA sequences, pleurastrophycean taxa, which, like the Ulvophyceae, possess a counter-clockwise arrangement of flagellar basal bodies, are more closely …

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Jeremy Rifkin Challenges Recombinant Dna Research: A Rhetoric Of Heresy., Wiley Michael Futrell Jan 1992

Jeremy Rifkin Challenges Recombinant Dna Research: A Rhetoric Of Heresy., Wiley Michael Futrell

LSU Historical Dissertations and Theses

Western culture, in large part, is a product of scientific inquiry, technological development and the ability to harness some of nature's resources. Much of society looks to science for technology-related solutions to many of its ills. As it develops new technology, science necessarily seeks to understand and control the forces of nature. Although science assumes a prominent role in contemporary society, that prominence does not necessarily translate into cultural consensus on the progress achieved by technological developments. Another perspective is represented by those who contend that continued technological advancement is the source of existing problems, not the solution. As these …

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Molecular Cloning, Expression And Site-Directed Mutagenesis Of A Complementary Dna Encoding Rabbit Muscle Fructose 6-Phosphate-1-Kinase., Jau-Yi Li Jan 1992

Molecular Cloning, Expression And Site-Directed Mutagenesis Of A Complementary Dna Encoding Rabbit Muscle Fructose 6-Phosphate-1-Kinase., Jau-Yi Li

LSU Historical Dissertations and Theses

This dissertation contains three parts based on my research project which investigates three aspects of rabbit muscle phosphofructokinase (ATP: D-fructose-6-phosphate-1-phosphotransferase, EC 2.7.1.11; PFK). The first part reports the isolation and characterization of two full-length rabbit muscle PFK cDNAs. The DNA sequences of these two cDNAs (cDNA-A and cDNA-B) show an identical coding sequence but heterogeneous 5$\sp\prime$untranslated regions. cDNA-A is formed by removal of a 1.7 Kb upstream intron while cDNA-B retains the 3$\sp\prime$region of this intron. The second part describes the expression of the cDNA in several bacterial hosts. Recombinant rabbit muscle PFK has been expressed at a significant level …

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Taxonomic Treatment Of Indigofera L. (Fabaceae: Faboideae) In The New World., Alan Wayne Lievens Jan 1992

Taxonomic Treatment Of Indigofera L. (Fabaceae: Faboideae) In The New World., Alan Wayne Lievens

LSU Historical Dissertations and Theses

The current taxonomic study of Indigofera (Fabaceae) as it occurs in the New World has several aims. The first addresses taxonomic and nomenclatural issues related to North American taxa. Because such issues have not been well understood for many of these taxa at various ranks, a synopsis of all taxa known to be referable to North America is presented along with a thorough discussion of nomenclatural issues (including synonymy) for each. This discussion is initially placed within the framework of the species groups proposed by Rydberg in 1923. A preliminary cladistic analysis of these North American species groups is presented. …

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Applicability Of Bioluminescence Assay And Aerobic Bacterial Counts For The Evaluation Of Raw Milk Quality., Abdul Ghafoor Mian Jan 1992

Applicability Of Bioluminescence Assay And Aerobic Bacterial Counts For The Evaluation Of Raw Milk Quality., Abdul Ghafoor Mian

LSU Historical Dissertations and Theses

Raw milk samples were analyzed to determine the bacteriological quality by the standard plate count (SPC), adenosine-5$\sp\prime$-triphosphate (ATP) assay, preliminary incubation counts, and the psychrotrophic bacteria count (PBC). In a comparison of SPC and ATP content, an overall correlation coefficient of 0.97 was found between the two methods. The correlations between ATP content and SPC of fresh raw milk samples at zero hour and after preliminary incubating these samples at 12.8 and 15.6$\sp\circ$C for 18 hours were.96,.97, and.97, respectively. The regression coefficients for all types of milk samples were highly significant ($P <$.01). High correlation coefficients demonstrated that the ATP measurement in combination with preliminary incubation practices could be a rapid technique for the determination of bacteriological quality of milk at receiving stations and milk processing plants. Median SPC for 175 fresh raw milk samples was 36,000/ml. The bioluminescence technique is reported previously to have a good correlation with SPC in the range of 1.0 $\times$ 10$\sp5$ to 1.0 $\times$ 10$\sp{10}$ bacteria/ml. The commingled milk coming at the receiving stations sometimes have a bacterial count that is less than 1.0 $\times$ 10$\sp{5}$ bacteria/ml. A correlation coefficient of.87 was calculated between the SPC and ATP values for the overall data while lowering the SPC range from 1.0 $\times$ 10$\sp5$ to 1.0 $\times$ 10$\sp4$ bacteria/ml. This range is more practical as a quick screening of raw milk at dairy processing facilities since 81 percent of all raw milk samples fell in this range. An equation (SPC = $-$1642213 + 6751(ATP)) was developed from the combined experimental data which could estimate the SPC of raw milk samples using their ATP content. Another phase of the experiment was to ascertain if the Petrifilm$\sp{\rm TM}$ technique could be effectively used in place of agar method to estimate PBC. The correlation coefficient between the Petrifilm$\sp{\rm TM}$ and the agar plate method for both the fresh and preliminary incubated raw milk samples was.99. A high linearity of relationship shows that one method can be substituted with the other. However, the Petrifilm$\sp{\rm TM}$ technique took longer than the usual time of 25 h to develop red colonies at 21$\sp\circ$C because of the slow reduction of the dye reagent triphenyl tetrazolium chloride (TTC) at this temperature.

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Modeling Of Circulation And Transport In Terrebonne Bay, Louisiana And Its Implications For Oyster Harvesting Management., Ellen J. Prager Jan 1992

Modeling Of Circulation And Transport In Terrebonne Bay, Louisiana And Its Implications For Oyster Harvesting Management., Ellen J. Prager

LSU Historical Dissertations and Theses

Contamination of oyster-rich waters in south Louisiana by sewage-related wastes is believed to occur on a seasonally varying basis, and pose a serious threat to both human welfare and the local economy. Fluctuations in the meteorologic and oceanographic conditions in the region are believed to be responsible for the variability observed in bacterial concentrations. To gain a better understanding of the relationship between transport processes, environmental forcing, and the potential for contamination, a combined program of in situ measurements and numerical modeling techniques was conducted in the nearshore waters of Terrebonne Bay, Louisiana. A finite element model based on the …

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Influences On The Instream Distribution Of Astyanax Fasciatus In A Small River In Costa Rica., Cecil Kelly Swing Jan 1992

Influences On The Instream Distribution Of Astyanax Fasciatus In A Small River In Costa Rica., Cecil Kelly Swing

LSU Historical Dissertations and Theses

The instream distribution of the tetra, Astyanax fasciatus, was investigated through approximately 700 hours of field observations in a small Costa Rican stream on the southwestern Pacific coast near Golfito. Individuals tended to remain in particular pools where they subsisted primarily on a diet of terrestrial insects. These fish were able to migrate, and only as many individuals stayed in any pool as could be sustained there by available food resources. Because the water intercepted insects fairly uniformly over its surface, the biomass of fish occupying any particular pool was proportional to its surface area (r$\sp2$ = 0.652). The amount …

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Effects Of Vertebrate Herbivory On Louisiana Coastal Marshes., Katherine Lynn Taylor Jan 1992

Effects Of Vertebrate Herbivory On Louisiana Coastal Marshes., Katherine Lynn Taylor

LSU Historical Dissertations and Theses

The disturbances of herbivory, simulated "eat-outs" (clipping and removal of above-ground biomass), and burning were examined for their effect on total biomass, individual species abundance, and species richness in several different marsh communities. Herbivory significantly reduced the total community biomass of all the marshes studied. Simulated "eat-outs" reduced the total biomass of the freshwater marsh but had no persistent effect on the total biomass of either the oligohaline or mesohaline marshes of the Pearl River. Both the oligohaline and the mesohaline marshes were able to recover from a removal of above-ground biomass (simulated "eat-out") within two years. The freshwater marsh …

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Interference, Management, And Growth Response Of Wild Poinsettia (Euphorbia Heterophylla L.) In Soybean., Teresa Summerford Willard Jan 1992

Interference, Management, And Growth Response Of Wild Poinsettia (Euphorbia Heterophylla L.) In Soybean., Teresa Summerford Willard

LSU Historical Dissertations and Theses

In field studies conducted in Louisiana in 1990 and 1991, area of influence, density, and duration of interference methodologies were used to evaluate wild poinsettia (Eupborbia heterophylla L.) interference in soybean (Glycine max (L.) Merr.). In 1990, soybean seed yield within 10 cm of wild poinsettia was similar to distances of 10 to 20 and 20 to 40 cm, but was less than that for distances greater than 40 cm from the weed. In contrast, soybean yields in 1991 growing within 10 cm of the weed were less than at greater distances. Weed interference resulted in a 9.4 and 18% …

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Characterization Of Gentamicin Resistance In Enteric Bacteria Isolated From Pseudomys Scripta-Elegans From Commercial Turtle Farms., Michelle Anne Brassett Jan 1992

Characterization Of Gentamicin Resistance In Enteric Bacteria Isolated From Pseudomys Scripta-Elegans From Commercial Turtle Farms., Michelle Anne Brassett

LSU Historical Dissertations and Theses

Several genera of aminoglycoside resistant enteric bacteria were isolated from commercial turtle farms. Citrobacter freundii and Proteus vulgaris were the most prevalent organisms. Gentamicin resistance, measured by minimum inhibitory concentrations (MIC), ranged as high as 100 $\mu$g/ml. While resistance to other antibiotics was detected in gentamicin-resistant isolates, no correlation was observed between antibiotic resistance and plasmid content. Spontaneous mutation to gentamicin could not account for the high levels of gentamicin resistance found in the original isolates. Regions of chromosomal DNA encoding gentamicin resistance of 100 $\mu$g/ml were obtained from two Citrobacter freundii, two Proteus vulgaris, and two Salmonella enteritidis strains. …

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The Use Of Hydrologically Altered Wetlands To Treat Wastewater In Coastal Louisiana., Andree Marie Breaux Jan 1992

The Use Of Hydrologically Altered Wetlands To Treat Wastewater In Coastal Louisiana., Andree Marie Breaux

LSU Historical Dissertations and Theses

Two major environmental problems currently affecting Louisiana are a high rate of coastal wetland loss and high levels of surface water pollution. The application of secondarily treated wastewater to wetlands is proposed as a means of dealing with these problems. The benefits of wetland wastewater treatment include improved surface water quality, increased accretion rates to balance subsidence, improved plant productivity, and decreased capital outlays for conventional engineering treatment systems. Wetland treatment systems can be designed and operated to restore deteriorating wetlands to previous levels of productivity. Hydrologically altered wetlands in the Louisiana coastal zone have been selected as appropriate for …

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Sorption, Kinetics, And Transport Of Selected Heavy Metals In Soil: A Laboratory Study And Modelling Approaches., Christoph Hinz Jan 1992

Sorption, Kinetics, And Transport Of Selected Heavy Metals In Soil: A Laboratory Study And Modelling Approaches., Christoph Hinz

LSU Historical Dissertations and Theses

The retention and transport behavior of heavy metals in soils is affected by soil chemical heterogeneity. The objectives of this study were to evaluate (i) the effects of heterogeneity on solute transport of heavy metals under steady water flow, (ii) the applicability of single solute and ion exchange isotherms to model Zn and Cd transport in soil columns, (iii) the modelling of the sorption kinetics of Zn under batch and flow conditions, and (iv) the effects of organic matter and iron oxide removal on the kinetics of Zn sorption in soils. A sensitivity analysis showed that site affinity distribution functions …

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