UNT Theses and Dissertations - 14 Matching Results

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An Assessment of the Use of Seeding, Mowing, and Burning in the Restoration of an Oldfield to Tallgrass Prairie in Lewisville, Texas

Description: An examination of the effectiveness of seeding, burning, and mowing in the reestablishment of tallgrass prairie species on overgrazed and abandoned pastureland. The study site is a 20 acre tract on U.S. Corps of Engineers land below Lake Lewisville in Denton County, Texas. The site was partitioned into thirty-nine 40 by 40 meter plots with seeding (carried out in 1996) and management treatment (burning, mowing, and no maintenance carried out in 1998) randomly applied following a two level desig… more
Date: August 1999
Creator: Windhager, Steven
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Biodiversity of Caddisflies (Trichoptera) of the Interior Highlands of North America

Description: Caddisflies (Trichoptera) were collected from over 500 different locations throughout the Interior Highlands (Ozark, Ouachita, Arbuckle, and Wichita Mountains) between March 1990 and March 1994. I systematically sampled representative lotic and lentic habitats in 131 natural watersheds that comprise the 17 different physiographic subregions of this area. From my examination of approximately 60,000 specimens, surveys of regional museum collections, and review of literature records, I document 22… more
Date: August 1994
Creator: Moulton, Stephen R. (Stephen Richard)
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Partner: UNT Libraries
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Biogeographic Relationships of Pocket Gophers (Geomys breviceps and Geomys bursarius) in the Southeastern Portion of Their Ranges

Description: This research utilized population genetic analyses (protein starch-gel electrophoresis and DNA sequencing of the cytochrome b mtDNA gene), host-parasite specificity (lice coevolution), remote sensing of satellite data, and geographic information systems (GIS) to characterize newly discovered populations of pocket gophers (genus: Geomys) in Arkansas. These populations are isolated and occur in seemingly unsuitable habitat in the Ozark Mountains of Arkansas. Analyses of electrophoretic and ectopa… more
Date: August 1998
Creator: Elrod, Douglas Allen
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Chronic Ventricular Sympathectomy : Effects on Myocardial Metabolism

Description: Chronic ventricular sympathectomy elicits changes in the coronary circulation, myocardial oxygen consumption and size of infarction resulting fromcoronary occlusion. These changes indicate a change occurring in the basic metabolism of the heart in response to the removal of its sympathetic nervous input. This hypothesis was tested using two groups of dogs, a shamoperated control and a ventricular sympathectomized group. The sympathectomy procedure was an intrapericardial surgical technique whic… more
Date: August 1993
Creator: Adix Longlet, Nancy J.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Comparison of Risk Assessment-Predicted Ecologically Safe Concentrations of Azinphos-Methyl and Fenvalerate to Observed Effects on Estuarine Organisms in a South Carolina Tidal Stream Receiving Agricultural Runoff

Description: A prospective ecological risk assessment method was developed evaluating the cumulative probabilistic impact of chemical stressors to aquatic organisms. This method was developed in response to the need to evaluate the magnitude, duration and episodic nature of chemical stressors on aquatic communities under environmental exposure scenarios. The method generates a probabilistic expression of the percent of an ecosystem's species at risk from a designated chemical exposure scenario.
Date: August 1997
Creator: Morton, Michael Gerard, 1957-
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Partner: UNT Libraries
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Development of Cardiovascular Regulation in Embryos of the Domestic Fowl (Gallus Gallus), with a Partial Comparison to Embryos of the Desert Tortoise (Gopherus Agassizii)

Description: In adult vertebrates, cardiovascular regulation is accomplished by numerous systems with neural, hormonal and local components responsible for the majority of regulation. These regulatory components work in concert to maintain the essential function of blood perfusion to adult tissues. Given the essential nature of this function it is therefore surprising that the development of cardiovascular regulation during gestation is poorly understood. The majority of what is known is based on a single v… more
Date: August 1999
Creator: Crossley, Dane Alan
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Discovery and Characterization of Two Tn5 Generated pyrA Mutants in Pseudomonas putida and the Generation of Hfr Strains

Description: A pyrA mutation in Pseudomonas putida was isolated using transposon mutagenesis for the first time. Transposon Tn5 was used to inactivate the pyrA gene for carbamoylphosphate synthetase in these mutants. Accordingly, these mutants were defective in pyrimidine and arginine biosynthesis. The suicide vector, pM075, from Pseudomonas aeruginosa, was used to introduce the transposon into the cells. Tn5 was subsequently used to supply homology so that the plasmid pM075 could be introduced in its entir… more
Date: August 1994
Creator: Liljestrand, Laura Gail
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Partner: UNT Libraries
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Effects of Trichinella Soluble Antigens on Macrophage Subpopulations

Description: The immunomodulatory effects of Trichinella spiralis or Trichinella pseudospiralis soluble antigen extracts were examined in an effort to characterize the differences in immune responses seen during these Trichinella infections. The newborn larvae extracts of either parasite exhibited similar potency for stimulating macrophage PGE production; however, the muscle larvae extracts of T. pseudospiralis stimulated greater levels of PGE than did the muscle larvae extracts of T. spiralis. These data c… more
Date: August 1992
Creator: Dixon, Guy Cameron, 1960-
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Partner: UNT Libraries
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Mechanisms of Cyanide Assimilation in Pseudomonas fluorescens NCIMB 11764

Description: Pseudomonas fluorescens NCIMB 11764 was capable of utilizing cyanide as a sole nitrogen source for growth. Cyanate (OCN") and S-cyanoalanine could also serve as nitrogenous substrates, but do not appear to play a role as intermediates in cyanide metabolism. Growth of this strain on cyanate as the sole nitrogen source led to the induction of an enzyme characterized as a cyanase (EC 3.5.5.3) based on its stoichiometric conversion of cyanate to ammonia, and dependence on bicarbonate for maximal ac… more
Date: August 1992
Creator: Nagappan, Olagappan
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Partner: UNT Libraries
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Molecular Phylogeny and Evolution of the American Woodrats, Genus Neotoma (Muridae)

Description: The evolutionary relationships of woodrats (Neotoma) were elulcidated through phylogenetic analyses of mitochondrial DNA restriction site and allozyme data. DNA samples from eleven nominal species from the genus Neotoma and two outgroup taxa, Ototylomys phyttotis and Xenomys nelsoni, were cleaved using a suite of 17 Type II restriction endonucleases. Mitochondrial DNA restriction profiles were visualized following electrophoresis of restriction digests via methods of Southern transfer and hybri… more
Date: August 1992
Creator: Planz, John Valentine
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Partner: UNT Libraries
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Morphological and Immunological Characterization of Earthworm Lumbricus terrestris Coelomocytes

Description: This research defines the morphological characteristics of the immune cells, coelomocytes, of the earthworm, Lumbricus terrestris. Such a definition of coelomocyte morphology can be correlated with immune function which will be of value in the development of a nonmammalian surrogate system to assess the immunotoxic potential of a terrestrial xenobiotics. Earthworms exposed to artificial soil dilutions of two complex xenobiotic mixtures, refuse derived fuel fly ash and a Superfund sire soil demo… more
Date: August 1992
Creator: Hariri, Maryam Feili
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Partner: UNT Libraries
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Naloxone Potentiation of Epinephrine Induced Vasoconstriction in Canine Skeletal Muscle Arteries

Description: Naloxone (NX) potentiated epinephrine (EPI) induced submaximal vasoconstriction in canine renal and skeletal muscle arterial segments, yet had no vasoconstrictor action alone. Developed tension generated in-vitro by 4 x 1mm. O.D. rings from 1st degree branches of canine femoral arteries was expressed as % of KCI induced maximum response. NX (10^-5 M) potentiated EPI induced submaximal contractions (34.2%) significantly more than contractions induced by norepinephrine, phenylephrine, lofexidine,… more
Date: August 1992
Creator: Stoll, Scott Thomas
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Partner: UNT Libraries
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Physical and Functional Characterization of the xy1XYZ Region From TOL Plasmid pDK1 and its Associated Downstream Regulatory Elements

Description: The nucleotide sequence for the pDKl TOL plasmid region encoding toluate-1,2-dioxygenase (Xy1XYZ, TO) was determined. TO is the first enzyme in the meta-cleavage operon, responsible for the conversion of toluates and benzoates to their carboxy-substituted diols. DNA sequence analysis revealed the presence of three open reading frames (ORF). The three ORFs correspond to xylX (1353 bp), xylY (486 bp) and xylZ (1008 bp), encoding predicted protein products of 51370 Da, 19368 Da and 36256 Da, respe… more
Date: August 1998
Creator: Hares, Douglas R. (Douglas Ryan)
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Partner: UNT Libraries
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Regulation, Evolution, and Properties of the ato Qperon and its Gene Products in Escherichia coli

Description: The regulation of short chain fatty acid metabolism has been examined. Metabolism of acetoacetate, and short chain fatty acids such as butyrate and valerate, is predicated upon the expression of genes of the ato operon. Acetoacetate induces expression of a CoA transferase (encoded by the atoDA genes) and expression of a thiolase (encoded by the atoB gene). Metabolism of saturated short chain fatty acids requires the activities of the transferase and thiolase and enzymes of 6-oxidation as well. … more
Date: August 1993
Creator: Chen, Chaw-Yuan
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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