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Articles 11701 - 11730 of 13623

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Synthesis Of Tryptophan And Tyrosine Derivatives., Li Shui Jan 1994

Synthesis Of Tryptophan And Tyrosine Derivatives., Li Shui

LSU Historical Dissertations and Theses

$\alpha$-Amino acids serve a central role in biology and chemistry. With the advance of a variety of sophisticated spectroscopic and computational methods to elucidate the relationships between amino acid sequence, protein conformation, and their chemical, physical, and biological properties, a tremendous level of interest has been generated in the de novo design and synthesis of unnatural amino acids for the purposes of imparting enzyme-inhibitory, antimetabolite, protease resistance, and unique conformational properties to peptides and derivatives. The goal of this research work was to synthesize tryptophan and tyrosine derivatives, which are conformationally constrained, with fixed side-chain to prevent $\alpha$-$\beta$ and/or $\alpha$-$\beta$ …

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The Design, Synthesis And Structure-Function Studies Of Highly Repetitive Amphiphilic Antibacterial Peptides And The Synthesis Of Benz(F)Indene For The Preparation Of Novel Metallocenes., Calvin Lawrence Becker Jan 1994

The Design, Synthesis And Structure-Function Studies Of Highly Repetitive Amphiphilic Antibacterial Peptides And The Synthesis Of Benz(F)Indene For The Preparation Of Novel Metallocenes., Calvin Lawrence Becker

LSU Historical Dissertations and Theses

Several different peptides exhibit antimicrobial activity based upon an amphiphilic $\alpha$-helical secondary structure. Antimicrobial action occurs because these peptides compromise the integrity of the cell membrane and ultimately cause cell lysis. It is believed that ion-channel formation is the mechanism by which this lysis occurs. The goal of this research has been to conduct structure-function studies of synthetic peptides to aid in the determination of the mode of action of lytic peptides. Several peptides based upon a minimalist approach have been synthesized. Amphiphilicity and $\alpha$-helicity were the desired structural features. With these as the necessary structural motifs we set out …

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Factors Affecting Asulam Activity On Sugarcane (Saccharum Sp.) Cultivars And Johnsongrass (Sorghum Halepense)., Stacey Alan Bruff Jan 1994

Factors Affecting Asulam Activity On Sugarcane (Saccharum Sp.) Cultivars And Johnsongrass (Sorghum Halepense)., Stacey Alan Bruff

LSU Historical Dissertations and Theses

Studies were conducted to evaluate several factors that may account for the variability in johnsongrass (Sorghum halepense (L.) Pers.) control and sugarcane (Saccharum sp.) cultivar sensitivity observed with postemergence application of asulam, methyl ((4-aminophenyl)sulfonyl) carbamate, herbicide. Johnsongrass at boot stage to 70% seedhead emergence was exposed to simulated rainfall (1.3 cm of water in 15 min) 0, 3, 6, 12, 24, and 48 h after application of asulam at 3.7 kg/ha. Predicted critical rainfree period at which greatest johnsongrass control (65 to 80%) was obtained ranged from 8 to 20 h after treatment, dependent on johnsongrass growth stage and environmental …

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Second Order Neural Networks., Sanjoy Das Jan 1994

Second Order Neural Networks., Sanjoy Das

LSU Historical Dissertations and Theses

In this dissertation, a feedback neural network model has been proposed. This network uses a second order method of convergence based on the Newton-Raphson method. This neural network has both discrete as well as continuous versions. When used as an associative memory, the proposed model has been called the polynomial neural network (PNN). The memories of this network can be located anywhere in an n dimensional space rather than being confined to the corners of the latter. A method for storing memories has been proposed. This is a single step method unlike the currently known computationally intensive iterative methods. An …

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Fluorescence Studies Of Tomaymycin-Dna Adducts: Structure And Dynamics., Qi Chen Jan 1994

Fluorescence Studies Of Tomaymycin-Dna Adducts: Structure And Dynamics., Qi Chen

LSU Historical Dissertations and Theses

The relationship between ground-state structure and fluorescence lifetime of tomaymycin was studied using steady-state and time-resolved fluorescence, absorption, NMR, and photochemical techniques. Excited-state proton transfer and intersystem crossing were identified as the major nonradiative processes. Solvent isotope effect was found in aqueous solution, which did not involved C8OH. Photochemical H-D exchange on aromatic C6H and C9H were observed with similar rate. At 77 K, the total luminescence quantum yield was determined as 0.99. The quantum yield ratio of phosphorescence to fluorescence was 1.2. The limiting anisotropy was ${\sim}0.34$ for fluorescence and $-$0.1 for phosphorescence. The number and type of tomaymycin-DNA …

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Factors Influencing Conceptual Change In Evolution: A Longitudinal, Multicase Study., Sherry Southerland Demastes Jan 1994

Factors Influencing Conceptual Change In Evolution: A Longitudinal, Multicase Study., Sherry Southerland Demastes

LSU Historical Dissertations and Theses

A high school Biology II classroom was observed daily in order to study students' conceptual change in evolution of life. The conceptual frameworks of four student participants were documented and the patterns of conceptual change were studied closely throughout the full school year. Data collected included open-ended and structured individual interviews, student journals, daily classroom observations, field notes, and pre-and posttests. All 68 student interviews (17 per student) were recorded, transcribed, coded, and sorted to find patterns of conceptual change. Additional interviews were conducted with the teacher, parents, principal, and high school counselor. The researchers' interpretations were shared with the …

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Isolation, Structural Elucidation And Structure-Activity Studies Of Natural Products From Regional Plants Of The Asteraceae., Tiansheng Lu Jan 1994

Isolation, Structural Elucidation And Structure-Activity Studies Of Natural Products From Regional Plants Of The Asteraceae., Tiansheng Lu

LSU Historical Dissertations and Theses

In a biochemical systematic study of the plant family Asteraceae combined with a search for bioactive natural products, the isolation and structural elucidation of secondary metabolites from seven plant species is reported. Investigation of the roots of Solidago canadensis provided six known and one new clerodane diterpenes related to kolavenic acid and five known matricaria ester-type polyacetylenes. The roots and aerial parts of Solidago rugosa afforded the known diterpenes kolavenol, hardwickiic acid, ($-$)-kaur-16-en-19-oic acid, (+)-manool, (+)-3$\beta$-hydroxymanool, manoyl oxide and ent-abietic acid and the new labdane diterpene, (+)-18-tigloyloxymanool, plus four new ent-abietane diterpenes. The isolation of two new and eight known …

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Role Of Curved Dna In Promoter Recognition With Bacillus Subtilis And Escherichia Coli Rna Polymerase., Cheryl Anne Nickerson Jan 1994

Role Of Curved Dna In Promoter Recognition With Bacillus Subtilis And Escherichia Coli Rna Polymerase., Cheryl Anne Nickerson

LSU Historical Dissertations and Theses

Intrinsically curved DNA upstream of the RNA polymerase binding site, the promoter, influences transcription in Bacillus subtilis. In this study, curved DNA upstream of the $-$35 region was examined for the ability to influence transcription in Escherichia coli and B. subtilis through the use of hybrid promoters. These promoters were constructed by substituting the curved DNA from two B. subtilis promoters, Bal129 and Alu156, for the DNA upstream of the $-$35 region in the lambda phage promoters $p\sb{\rm R}$ and $p\sb{\rm L}$. The hybrid promoters were designated Bal$p\sb{\rm R}$, Alu$p\sb{\rm R}$, Bal$p\sb{\rm L}$, and Alu$p\sb{\rm L}$. Using transcriptional fusions between …

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The Legacy Of America's "Forgotten Warriors:" An Analysis Of Dysfunctional Relational Communication Among Vietnam Combat Veterans Exhibiting Posttraumatic Stress Disorder Symptomatology., Jack Eugene Rogers Jan 1994

The Legacy Of America's "Forgotten Warriors:" An Analysis Of Dysfunctional Relational Communication Among Vietnam Combat Veterans Exhibiting Posttraumatic Stress Disorder Symptomatology., Jack Eugene Rogers

LSU Historical Dissertations and Theses

The literature has long reported the atypical stress-producing characteristics of the Vietnam conflict. For veterans still suffering from the psychological and emotional "fall-out" of war-related anxiety, one long-term adjustment dysfunction is the difficulty PTSD-positive veterans experience in sustaining successful interpersonal relationships. Competent dyadic communication plays a critical role in engendering positive relational trajectories. This study investigated the hypothesis that posttraumatic stress disorder would exhibit a correlational relationship with the relational communication topoi of intimacy and dominance/control. A cross-regional sample of 218 PTSD-positive veterans and their relational partners provided data. Scale construction and validation was achieved through orthogonal factor analysis with …

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Nutrient Restriction In Mares: Plasma Metabolite And Hormonal Characterization And Responses To Feeding And Metabolic Challenges., Leeann Salathe Sticker Jan 1994

Nutrient Restriction In Mares: Plasma Metabolite And Hormonal Characterization And Responses To Feeding And Metabolic Challenges., Leeann Salathe Sticker

LSU Historical Dissertations and Theses

Three experiments were designed to provide a comprehensive reference for the responses of plasma metabolites and hormones to control and restricted intakes of protein and(or) energy and to feed deprivation. The objectives of the first and second experiments were to characterize the effects of protein and(or) energy restriction on glucose, insulin, nonesterified fatty acids (NEFA), urea nitrogen (N), insulin like growth factor-1 (IGF-1), cortisol, triiodothyronine ($T\sb3$, thyroxine ($T\sb4$), prolactin, and growth hormone (GH) concentrations in plasma on a daily basis, after feeding, and after i.v. administration of glucose or epinephrine. The third experiment was conducted to answer questions of how …

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Permethrin Resistance In The Soybean Looper, Pseudoplusia Includens (Walker): Geographic Variation, Mechanisms, Inheritance, And Host Plant Effects., James Donald Thomas Jr Jan 1994

Permethrin Resistance In The Soybean Looper, Pseudoplusia Includens (Walker): Geographic Variation, Mechanisms, Inheritance, And Host Plant Effects., James Donald Thomas Jr

LSU Historical Dissertations and Theses

Field strains of soybean looper, Pseudoplusia includens (Walker), from Louisiana, Texas, and Puerto Rico were tested for permethrin synergism by piperonyl butoxide (PB) and S,S,S tributylphosphorotrithioate (DEF). Resistance was completely suppressed by 10 $\mu$g PB/larva in strains from Louisiana with 2.7 to 14.1-fold resistance. The Texas strain was 14.8-fold resistant and permethrin toxicity was increased 8.6-fold by PB. The Puerto Rico strain was highly resistant to permethrin (426.6-fold) and PB increased permethrin toxicity only 4.6 and 7.5-fold, respectively, at 10 and 20 $\mu$g/larva. No significant synergism resulted from DEF treatment in any of the strains tested. In field trials, efficacy …

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Host Plant Adaptation In The Two Strains Of Fall Armyworm (Lepidoptera: Noctuidae)., Klaas H. Veenstra Jan 1994

Host Plant Adaptation In The Two Strains Of Fall Armyworm (Lepidoptera: Noctuidae)., Klaas H. Veenstra

LSU Historical Dissertations and Theses

The fall armyworm (Spodoptera frugiperda J. E. Smith) Lepidoptera: Noctuidae) consists of two genetically differentiated strains. The corn strain feeds on corn and the rice strain feeds primarily on rice and forage grasses. My research focused on host plant adaptations within each strain as assessed by larval performance and enzymatic responses to feeding upon different hosts. Three sets of experiments were conducted. The first experiment examined consumption and utilization in both strains reared on corn. In the second experiment, mixed-function oxidase (MFO) and general esterase enzyme activities were measured from larvae of both strains that were reared on corn, bermudagrass, …

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"A Proper Little Lady" And Other Twisted Tales Of Adolescent Femininity., Natalie Guice Adams Jan 1994

"A Proper Little Lady" And Other Twisted Tales Of Adolescent Femininity., Natalie Guice Adams

LSU Historical Dissertations and Theses

The purpose of this ethnographic study is to explore the stories told by four adolescent females about how they construct a gendered identity amidst the conflicting and contradictory expectations of them as adolescents and as females. After situating the study within a feminist poststructuralist framework, the dominant cultural scripts that have dictated what constitutes normative adolescent and feminine behavior are examined. Of particular importance to this study is the way in which these dominant discourses of femininity and adolescence are manifested in the middle school that the participants attend, especially in the school's attempt to mold its female students into …

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Factors Affecting Sediment Transport, Deposition And Erosion In Intertidal Wetlands In Louisiana., Roelof Maria Boumans Jan 1994

Factors Affecting Sediment Transport, Deposition And Erosion In Intertidal Wetlands In Louisiana., Roelof Maria Boumans

LSU Historical Dissertations and Theses

Processes leading to land loss in Louisiana are defined, measured and analyzed with special emphasis on the deposited and suspended sediment budgets. The findings were used to assess coastal management in Louisiana. In a spatial model of long term habitat succession, the degradation of a Louisiana wetland was based upon simulated exchanges of sediments across irregularly shaped polygons. Habitat distribution within a cell was estimated by elevation. The model findings were confirmed when the impact of two Louisiana marsh management plans caused reduced short-term sedimentation due to impaired water and materials flux. The sedimentation-erosion table (SET) is described and applied …

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Tolerance Potential And Defense Mechanisms Of Honey Bees (Apis Mellifera L.) To Varroa Jacobsoni Oud. (Acari: Varroidae) And Acarapis Species (Acari: Tarsonemidae)., Lilia Ibay De Guzman Jan 1994

Tolerance Potential And Defense Mechanisms Of Honey Bees (Apis Mellifera L.) To Varroa Jacobsoni Oud. (Acari: Varroidae) And Acarapis Species (Acari: Tarsonemidae)., Lilia Ibay De Guzman

LSU Historical Dissertations and Theses

Comparative resistance or tolerance of four stocks of Apis mellifera L. to Varroa jacobsoni Oudemans, Acarapis dorsalis Morgenthaler, Acarapis externus Morgenthaler and Acarapis woodi (Rennie), was investigated using choice (bioassay) and field experiments. A. m. carnica from Yugoslavia (ARS-Y-C-1), A. m. carnica from Canada (Hastings), F$\sb1$ hybrid between ARS-Y-C-1 and Hastings and a general Louisiana stock were evaluated. A tolerance index showed that Hastings, ARS-Y-C-1 and F$\sb1$ hybrid exhibited some degree of tolerance to V. jacobsoni. These stocks lived longer with higher levels of Varroa infestation in worker pupae and on adult honey bees. Louisiana stock was more susceptible to …

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Nitric Oxide Toxicity Mediated By Peroxynitrite., Xia Jin Jan 1994

Nitric Oxide Toxicity Mediated By Peroxynitrite., Xia Jin

LSU Historical Dissertations and Theses

The reaction of nitric oxide (NO) with superoxide forms peroxynitrite, an extremely potent oxidant. Peroxynitrite can be synthesized by the ozonation of the azide ion. This preparation of peroxynitrite is essentially free of hydrogen peroxide and does not contain excess alkali. Peroxynitrites synthesized by independent methods contain very different impurities, but give the same results toward the oxidation of methionine (Met), dimethylsulfoxide, and the nitration of phenols. The oxidations of Met and its analog, 2-keto-4-thiomethylbutanoic acid (KTBA), by peroxynitrite proceed by two competing mechanisms. The first is a non-radical, bimolecular reaction yielding methionine sulfoxide (MetS=O). In the second mechanism, methionine …

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Demographic And Genetic Studies Of Seed Dispersal And Juvenile Survival In An Old-Growth Longleaf Pine Population., Susan Langevin Grace Jan 1994

Demographic And Genetic Studies Of Seed Dispersal And Juvenile Survival In An Old-Growth Longleaf Pine Population., Susan Langevin Grace

LSU Historical Dissertations and Theses

Many biotic and abiotic factors contribute to the formation of aggregations of seedlings and juveniles in populations of forest trees. The following studies investigate factors influencing the spatial structure of juveniles in an old-growth longleaf pine (Pinus palustris Mill.) population. In the first study, effects of adult tree density, pine needle litter and fire temperature were related to the demography of juveniles. A cohort of juveniles from a mast year in 1987 was followed over four years. Demographic components were determined both before and up to two years after fire. Juveniles were more dense, larger and had higher survival in …

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Fundamental Studies Of Capillary Electroosmosis And Electrokinetic Removal Of Phenol From Kaolinite., Heyi Li Jan 1994

Fundamental Studies Of Capillary Electroosmosis And Electrokinetic Removal Of Phenol From Kaolinite., Heyi Li

LSU Historical Dissertations and Theses

Capillary electroosmosis is an important factor in capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MECC). A new application of electrokinetic phenomena in environmental science is electrokinetic soil processing, which is an emerging technique with the capability to decontaminate polluted soils. Chapter 1 discusses the fundamental theory behind electroosmosis, CZE, MECC, and electrokinetic soil processing. In chapter 2, the surface conductances of different concentrations of KCl solutions in 50 and 100 $\mu$m capillaries were measured using an AC method, to attempt to characterize capillary double layers. With increase of KCl concentration, the surface conductance increases. Chapter 3 involves fundamental …

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Colonial Natal, 1838 To 1880: The Making Of A South African Settlementsystem. (Volumes I And Ii)., Darrell Peter Kruger Jan 1994

Colonial Natal, 1838 To 1880: The Making Of A South African Settlementsystem. (Volumes I And Ii)., Darrell Peter Kruger

LSU Historical Dissertations and Theses

The study of colonial settlement policy is one way for human geographers to understand how people shape the places they inhabit. The major concern of this study was to determine the impact of Dutch-Afrikaner, Native, and British cultures on the Natal colonial settlement system between 1838 and 1879. A prolonged era (1844-1879) of British settlement policy was preceded by a brief period of Dutch-Afrikaner hegemony (1838-1843). I test the hypothesis that Natal's British settlement system was a syncretic compromise between European and South African (Native and Dutch-Afrikaner) adaptations. My interpretation turns on frontier processes of transfer and borrowing. I suggest …

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Translational Studies Of Equine Infectious Anemia Virus Rna And Analysis Of The Viral Regulatory Proteins., Rodney Louis Schiltz Jan 1994

Translational Studies Of Equine Infectious Anemia Virus Rna And Analysis Of The Viral Regulatory Proteins., Rodney Louis Schiltz

LSU Historical Dissertations and Theses

The 3.5-kb RNA of equine infectious anemia virus (EIAV) is shown here to encode the S1, S2 and envelope proteins in vitro. S1 is expressed from this RNA despite the lack of an AUG codon. Deletion mutants of a cDNA derived from the 3.5-kb RNA were used to determine that sequences within the first 14 codons of ORF S1 are required for S1 expression in vitro and trans-activation in vivo. Amino-terminal sequence analysis of the in vitro synthesized S1 protein is consistent with initiation at a CUG codon. The translation properties of the 3.5-kb RNA have been examined in wheat …

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Seasonal And Spatial Abundance And Size Distribution Of Fishes Associated With A Petroleum Platform In The Northern Gulf Of Mexico., David Robert Stanley Jan 1994

Seasonal And Spatial Abundance And Size Distribution Of Fishes Associated With A Petroleum Platform In The Northern Gulf Of Mexico., David Robert Stanley

LSU Historical Dissertations and Theses

The purpose of this study was to demonstrate the utility of dual-beam hydroacoustics in measuring abundance and target strength of fishes near a petroleum platform in the northern Gulf of Mexico. From September to November 1990 fish densities ranged from 0 to 1.88 fish/m$\sp3$ and varied with platform side, depth, time of day and month. Densities were highest adjacent to the platform and decreased significantly beyond 9 m. Approximately 2,400 to 8,300 fish were associated with the platform depending on month. Target strengths ranged from $-$56 to $-$24 dB and varied with side of the platform and month. Mean monthly …

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Kinetics Of The Immune Response To Mycobacterium Paratuberculosis Of Resistant And Susceptible Mice., Ronald Sidney Veazey Jr Jan 1994

Kinetics Of The Immune Response To Mycobacterium Paratuberculosis Of Resistant And Susceptible Mice., Ronald Sidney Veazey Jr

LSU Historical Dissertations and Theses

The resistance and immunologic responses of a Bcg susceptible (C57BL/6) and Bcg resistant (C3H/He) strain of mouse were compared after infection with Mycobacterium paratuberculosis. Bacterial resistance was evaluated by bacterial counts and histopathology of chronically infected mice. Levels of non-specific macrophage activation and the response of various T cell subsets were also evaluated following infection. Susceptible mice orally infected with Mycobacterium paratuberculosis developed granulomatous lesions containing acid-fast bacteria in the mesenteric lymph nodes. Significant differences in CFU of M. paratuberculosis were observed between C57BL/6 and C3H/He mice following an i.p. infection. Susceptible mice failed to limit bacterial proliferation, while bacterial …

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Effect Of Processing On Protein And Carotenoids In Weaning Food Formulated From Sweetpotatoes, Or Apios Americana., Michael Andrew Ameny Jan 1994

Effect Of Processing On Protein And Carotenoids In Weaning Food Formulated From Sweetpotatoes, Or Apios Americana., Michael Andrew Ameny

LSU Historical Dissertations and Theses

White flesh sweetpotatoes (Ipomoea batatas (L.) Lam) are a major food crop in developing countries. This study was to evaluate the protein and carotenoid content and quality of various white fleshed African sweetpotatoes and Apios americana tubers for use as a weaning food. The sweetpotato and Apios are not normally considered sources of carotenoids and proteins, but the wide use of sweetpotatoes as a source of carbohydrate and the renewed interest in Apios warrant the study of carotenoids and proteins in these crops. Total carotenoids ranged from 0$\mu{\rm g}$/100g to 260$\mu$g/100g (fresh weight basis) for sweetpotatoes. Apios total carotenoids ranged …

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Effect Of Temperature, Cell Concentration, And Split Dose Gamma Radiation On The Radiosensitivity Of Listeria Monocytogenes., Linda S. Andrews Jan 1994

Effect Of Temperature, Cell Concentration, And Split Dose Gamma Radiation On The Radiosensitivity Of Listeria Monocytogenes., Linda S. Andrews

LSU Historical Dissertations and Theses

Among food-borne pathogens, Listeria monocytogenes is one of the more resistant to food processing methods, including irradiation. USFDA approval for irradiation of processed meat and seafood products likely to contain Listeria spp. is $<$3 kGy gamma radiation. The incidence of L. monocytogenes in food products varies between 5-30% and at levels $<10\sp4$ CFU/g. With the capacity of this bacterium to multiply at refrigeration temperatures and the zero tolerance level mandated by the USFDA it becomes imperative to maximize the efficiency of the irradiation process. The first purpose of this study was to determine if initial cell concentration and/or temperature at time of irradiation influences the radiosensitivity of L. monocytogenes. Secondly, to determine whether split dose application would effect the radiation response of this bacterium. Concentrations of 10$\sp3,$ 10$\sp6$ and 10$\sp9$ cfu/ml of L. monocytogenes Scott A, were suspended in tryptic soy broth and exposed to 0-5 kGy gamma (1.25MeV) radiation at 20, 4, and -80$\sp\circ{\rm C}.$ Split doses were applied in equal portions to initial cell concentrations of 10$\sp6$ and 10$\sp9$ at the same temperatures. Surviving cells under the various conditions were enumerated and irradiation D-values were calculated from linear regression curves. At all temperatures, cell concentrations of 10$\sp3{\rm CFU/ml}$ were reduced to non recoverable levels with 2 kGy gamma radiation. The irradiation D-value of 0.43 kGy for frozen (-80$\sp\circ{\rm C})$ cultures of 10$\sp6$ CFU/ml was significantly lower (p $<$ 0.05) than the D-values (0.58 and 0.62 kGy) for the same cell concentration at the other two temperatures (20$\sp\circ$ and 4$\sp\circ{\rm C},$ respectively). For higher cell concentration of 10$\sp9$ cfu/ml, a D-value of 0.42 kGy was obtained for both 4$\sp\circ{\rm C}$ and -80$\sp\circ{\rm C}$ these were significantly lower (p $<$ 0.05) than 0.50 kGy for 20$\sp\circ{\rm C}$ suspensions. With both cell concentrations, the lowest D-values were obtained when cells were irradiated in the frozen state indicating a that primary cell damage was due to direct effects of irradiation. Split doses of 1 and 2 hours time between fractions approached the generation times for this bacterium and were significantly reduced at 20$\sp\circ{\rm C}.$ However, there was no consistent trend in reductions at 4$\sp\circ$ or -80$\sp\circ{\rm C}.$ Split dose application of irradiation to food pathogens should be further explored.

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Life History Responses To Fire Season In A Clonal Herb, Pityopsis Graminifolia (Asteraceae)., John Stephen Brewer Jan 1994

Life History Responses To Fire Season In A Clonal Herb, Pityopsis Graminifolia (Asteraceae)., John Stephen Brewer

LSU Historical Dissertations and Theses

The effects of three fire seasons (May, August, and January) on reproductive success and clonal growth of a golden aster (Pityopsis graminifolia) were examined within experimental burn plots in a longleaf pine savanna in north Florida. Several factors influenced reproductive success in this species, including rates of floral induction and bud herbivory, clone fecundity, and seedling dynamics. Flowering was induced by fire, especially when it occurred in May or August. Fire season affected rates of floral induction and bud herbivory by as much as one to two orders of magnitude. Sizes of bolting shoots were also affected by fire season. …

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The Development And Evaluation Of Impedance Technology To Determine The Quality Of Shrimp And Catfish., Patti Lynn Wiese Lehigh Jan 1994

The Development And Evaluation Of Impedance Technology To Determine The Quality Of Shrimp And Catfish., Patti Lynn Wiese Lehigh

LSU Historical Dissertations and Theses

Impedance technology is currently used as a measurement of microbial activity. The purpose of the current study was to determine the feasibility of utilizing impedance technology to evaluate the quality of white shrimp (marine species) and channel catfish (freshwater species). Impedance analysis measurements (I-values) of raw shrimp increased for samples stored at 5, 25, and 35$\sp\circ$C; however, control samples stored at $-$20$\sp\circ$C displayed no significant changes in I-values. I-values from thermally processed shrimp had no direct relationship with odor scores, increased storage time, or increased storage temperature. It was concluded that while impedance measurements were able to indicate the degree …

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Investigations On Insecticide Resistance In Tobacco Budworm, Heliothis Virescens (F.), And Boll Weevil, Anthonomus Grandis Grandis Boheman, In The Mid-South., Scott Hamilton Martin Jan 1994

Investigations On Insecticide Resistance In Tobacco Budworm, Heliothis Virescens (F.), And Boll Weevil, Anthonomus Grandis Grandis Boheman, In The Mid-South., Scott Hamilton Martin

LSU Historical Dissertations and Theses

Topical bioassays were conducted in 1991 to develop dose-mortality lines for the LSU laboratory reference colony (LSU-LAB) and field-collected colonies of tobacco budworm, Heliothis virescens (F.), from Louisiana, Mississippi and Texas. Field-collected colonies exhibited resistance to cypermethrin (1-41x), profenofos and sulprofos (1-8x), methomyl (2-6x) and no resistance to endosulfan compared to the LSU-LAB colony. Diagnostic dose bioassays were developed to facilitate rapid testing of field-collected colonies for resistance to insecticides. These diagnostic dose bioassays were conducted in 1992 and 1993 on the LSU-LAB colony, a North Carolina laboratory reference colony and field-collected colonies from Louisiana, Oklahoma and Texas. Significant (P …

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Latitudinal Gradients In Temperate And Tropical Seasonal Forests., Martin Francis Quigley Jan 1994

Latitudinal Gradients In Temperate And Tropical Seasonal Forests., Martin Francis Quigley

LSU Historical Dissertations and Theses

In an analysis of latitudinally replicated one hectare samples, nine seasonal forests of the temperate and tropical Americas were found to be very similar in biomass, stratification and patterns of spatial dispersion, regardless of taxonomic composition or relative stem density. Neither basal area nor relative size class distributions of trees differed significantly among latitudes from the equator to 40$\sp\circ$ north. While overall plant density was greater in tropical forests, the numbers and composition within individual strata--shrub layer, subcanopy, canopy, and liana--interacted independently and significantly with latitude. Understory populations were denser and more speciose at middle latitudes, in forests frequently affected …

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The Production And Characterization Of Alginate Produced By Pseudomonas Syringae., Richard David Ashby Jan 1994

The Production And Characterization Of Alginate Produced By Pseudomonas Syringae., Richard David Ashby

LSU Historical Dissertations and Theses

Alginate has many industrial uses because of its unique colloidal behavior, and its ability to thicken, stabilize, emulsify, suspend, form films, and produce gels. Currently, all commercial alginate comes from brown algae, where it exists naturally as a structural material. Many different types of brown algae produce alginate but it can only be obtained in sufficient quantity and quality from a limited number of species. On the basis of location, at least half of the world's resources of this polymer are potentially at risk due either to political instability or industrial pollution. Bacteria provide a potentially unlimited alternate source for …

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Sedimentation Processes In Selected Coastal Wetlands From The Gulf Of Mexico And Northern Europe., John Charles Callaway Jan 1994

Sedimentation Processes In Selected Coastal Wetlands From The Gulf Of Mexico And Northern Europe., John Charles Callaway

LSU Historical Dissertations and Theses

Sediment cores were collected from coastal wetlands from the Gulf coast of North America and northern Europe to study accretion rates and heavy metal accumulation. There was a significant decrease in vertical accretion rates from low to high marsh for Gulf coast samples. Contrary to previous results, these low tidal range sites did not have negative accretion balances. Northern European samples demonstrated the utility of Chernobyl $\sp{137}$Cs as a sediment marker. There were large differences in sediment characteristics and accretion rates between Polish and western European samples. Vertical accretion rates based on $\sp{210}$Pb were lower than $\sp{137}$Cs rates for most …

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