UNT Theses and Dissertations - 351 Matching Results

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Biological Indices of Stream Pollution

Description: A thorough biological survey and evaluation is a lengthy and expensive project. The number of technically trained persons required prevent its use by most public agencies. Since public health departments are the groups most frequently concerned with measuring the effects of pollution in streams, a need exists for a simplified method of sanitary survey. Recognizing this need, the Texas Health Department assigned the writer the problem of devising a method of survey which would require a field party of two and could be conducted entirely from a mobile field laboratory.
Date: August 1952
Creator: Russell, James C.
Partner: UNT Libraries

Biosystematic Study of a Desmodium Complex

Description: An examination of the Desmodium canescens complex (D. canescens; D. tweedyi; D. illinoense) has resulted in the delimitation of a previously unreported alliance between D. canescens and D. tweedyi. The following points support this view: (a) morphological data taken from herbarium and garden specimens indicate that for many characters, the mean values of D. canescens and D. tweedy are not significantly different (b) breeding experiments have shown that artificial interspecific hybridization is possible between D. canescens and D. tweedyi (c) cytological studies have shown that D. canescens and D. tweedyi have a base number of x = 11, while D. illinoense has a base number of x = 10. A new combination is suggested: Desmodium canescens var. tweedyi (Britt.) Williams.
Date: December 1977
Creator: Williams, John G., 1949-
Partner: UNT Libraries

Capillary Permeability to Narrow-Range Macromolecular Dextrans at Normal and Hypobaric Pressures

Description: In view of its varied concepts and interpretations, and because of the discrepancies produced by the previous utilization of polydispersed dextrans, a study using extremely narrow-range molecular weight dextran fractions was initiated to reevaluate and consolidate some of the aspects of capillary permeability. A portion of the study was performed under decreased barometric pressure in order to clarify further some of the mechanisms involved in particulate transfer across the capillary endothelial membranes. Gel filtration procedures augmented the study as an assessment of the polydispersity effects of the dextrans employed.
Date: December 1972
Creator: Norris, John Anthony
Partner: UNT Libraries

Changes in Heterozygosity Through Time in American Standardbred and American Saddlebred Horses (1960-1990)

Description: Observed and expected heterozygosity (H) levels for ten electrophoretic blood marker loci and expected H for seven red blood cell (RBC) anitgen/antibody loci were examined for 20 years in American Standardbred and 30 years in American Saddlebred horses. Standardbreds were classed by gait, Trotter and Pacer, and evaluated separately in most analyses. 4,404 Trotters and 12,271 Pacers were found to have statistically highly significant losses of mean total observed H through time for the ten electrophoretic loci (P<0.005), although in Trotters the loss was more extreme (P<<0.001). Loss of H in 5984 Saddlebreds was not significant (P=0.259). Correlations of RBC expected H through time showed decreases in all three groups.
Date: May 1992
Creator: King, Judith A. (Judith Ann), 1955-
Partner: UNT Libraries

Chemical and Physiological Properties of an Antibiotic Produced by a Variant of the Penicillium Notatum-Chrysogenum Group

Description: The present study of the production and properties of an antibiotic was undertaken in the hope that some useful information could be contributed to a long-range investigation program being carried on at North Texas State Teachers College. This program is concerned with the production of a useful antibiotic from a variant of the Penicillium notatum-chysogenum group of molds.
Date: 1947
Creator: Conyers, Loyd, W.
Partner: UNT Libraries

Circulatory and Respiratory Responses to Cycle Ergometry at Different Pedal Rates

Description: The effects of moderate workload exercise at different pedal rates on circulatory and respiratory parameters were studied. Five subjects performed seven discontinuous constant-load cycle ergometer tests of 30 minutes duration at pedal rates of 40, 50, 60, 70, 80, 90 and 100 rpm. Oxygen uptake and carbon dioxide production were determined by standard open circuit spirometry, while heart rate was recorded by electrocardiograph. The CO₂ rebreathing procedure was administered during the exercise bout in order to determine cardiac output. Blood pressure was determined for each test, and total peripheral resistance was calculated. The findings indicate that progressive increases in pedal frequency during discontinuous constant-load cycle ergometry produce progressive increases in cardiovascular, respiratory and metabolic responses and a decrease in gross exercise mechanical efficiency. The results indicate that oxygen uptake, cardiac output, heart rate, ventilation and arterial-venous oxygen difference increases curvilinearly as pedal rate increases, possibly as a result of increases in recruitment of muscle fibers and/or muscle groups. These findings suggest that circulatory and respiratory responses are due to "central command" which sets the basic efferent response pattern. However, this effector pattern is modulated by afferent input originating from the legs during progressive increases in pedal rate.
Date: May 1991
Creator: Hernandez, Raymundo
Partner: UNT Libraries

A Comparative Study of Egg Media in the Primary Isolation of Mycobacterium Tuberculosis

Description: The primary purpose of this investigation is not only to improve the present technique of culture of Mycobacterium tuberculosis, but also to make a comparative study of the media use, namely, Veterans Administration modification of Trudeau's medium, Lowenstein's egg medium, and that developed by the author, in order to find which, if any, of these will most easily and effectively meet the needs of the hospital laboratory.
Date: 1949
Creator: Barberousse, Loris J.
Partner: UNT Libraries

A Comparative Study of Four Genealogies to Determine Predisposition to Cancer

Description: This study was made in an effort first, to determine the mode of transmission of the inheritance of a predisposition to cancer as revealed through the analyses of four separate human genealogies, and second, to make a comparative study of the genealogies to determine whether the mode of transmission is the same.
Date: 1941
Creator: Andrew, Vivian Wilson
Partner: UNT Libraries

Comparative Toxicity Responses in Earthworms Lumbricus Terrestris and Eisenia Foetida to Cadmium Nitrate and Chlordane Using Artificial Soil and Filter Paper Exposures

Description: This research compares LC50 and LD50 of earthworms, Lumbricus terrestris and Eisenia foetida exposed to cadmium nitrate and chlordane using 48-h contact filter paper (FP) and 14-d artificial soil (AS) protocols. Both LC50 and LD50 showed that chlordane was more toxic than cadmium in both species regardless of the exposure. The reference toxicant 2-chloroacetamide using the standardized 48-h FP exposure was used to assess the general response of the earthworm prior to toxicity experiments. A glucose test was developed as an internal standard to assess homogeneity of mixtures among both replicates and dilutions. Accuracy of dilutions is assessed by the slope of a regression line relating nominal dilution to observed internal standard concentration. Precision of replicate preparation is assessed by among replicate variance.
Date: August 1992
Creator: Muratti Ortiz, Joseph F.
Partner: UNT Libraries

Comparative Ultrastructural Study between Young and Adult forms of Trypanosoma Lewisi

Description: The purpose of this study was to examine the ultrastructure of both young (dividing form) and adult (stationary form) of Trypanosoma lewisi. Changes observed between the two forms of the organism were related directly to data obtained from previous comparative biochemical studies conducted on these forms of Trypanosoma lewisi.
Date: August 1973
Creator: Abdul-Salam, Jasem M.
Partner: UNT Libraries

A Comparison of Predicted and Actual Trophic Status of Lake Ray Roberts, Texas Based on Chlorophyll A

Description: Two years before impoundment, the trophic status of Lake Ray Roberts was predicted by applying the total phosphorus input into the Organization for Economic Cooperation and Development (OECD) eutrophication model. Predicted mean summer epilimnetic (MSE) chlorophyll a of Elm Fork arm, Isle duBois arm and Main Body were in the eutrophic category of the OECD model. Observed MSE chlorophyll a two years after impoundment of Elm Fork arm, Isle duBois and Main Body had not reached their predicted means and were at the mesotrophic-eutrophic boundary of the OECD model. Six years after impoundment, observed MSE chlorophyll a for Main Body, was closer to its predicted mean and in the eutrophic category of the OECD model. Six years after impoundment, Elm Fork arm was the most productive area of Lake Ray Roberts. Observed means of chlorophyll a, total phosphates, suspended solids and turbidity were often highest in the Elm Fork arm. Wastewater effluent from Gainesville and Valley View, TX, had an impact on productivity in Elm Fork arm.
Date: May 1999
Creator: Lytle, Lili Lisa
Partner: UNT Libraries

A Correlation of the Vegetation with the Soil Types of Haskell County, Texas

Description: The problem has consisted, first, of a mapping of the soil types present in Haskell County; second, a collection of the existing vegetation of each soil type; third, an identification of the vegetation collected and observed; fourth, and lastly, a comparative study of the vegetation of each soil type in an effort to establish a correlation between the vegetation and the soil type.
Date: 1950
Creator: Tyson, Josiah William, Jr.
Partner: UNT Libraries

The Cultural, Physiological, Morphological and Chemical Characteristics of an Actinomycete from Lake Waco, Texas

Description: The purpose then of this paper has been to expand our knowledge of these aquatic forms by investigating the cultural, physiological, morphological, and chemical characteristics of an actinomycete isolated from the water supply, Lake Waco, of Waco, Texas.
Date: January 1954
Creator: McCormick, William C.
Partner: UNT Libraries