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The Effects of Pulp and Paper Mill Wastewaters on Phytoplankton Primary Productivity in the Red River, Louisiana
Responses of phytoplankton productivity in the Red River to unbleached pulp and paper mill wastewaters were monitored using in situ ^14C incubation. Preoperational studies, conducted prior to the discharge of mill wastewaters varied seasonally, but revealed similar productivity trends when compared with postoperational studies, conducted after mill discharges began entering the Red River. Carbon assimilation rates measured downstream of mill discharge were generally greater than upstream levels in both preoperational and postoperational studies. Selected physical, chemical, and biological parameters varied seasonally, but showed similar upstream-downstream values and preoperational-postoperational values. Total Organic Carbon (TOC), Dissolved Organic Carbon (DOC), and Biochemical Oxygen Demand (BOD_5) were positively correlated with postoperational productivity rates. Apparent color was negatively correlated with productivity rates.
Date:
May 1984
Creator:
Holler, Jeffrey Dee
System:
The UNT Digital Library
The President's Influence on Congress: Toward an Explanation of Senators' Support for Presidents Carter and Reagan
This study examines the possible effect of the president's vote totals in states on Presidents Carter's and Reagan's support among senators. Using senators' Congressional Quarterly (CQ) presidential support scores as the dependent variable, this paper hypothesizes that Carter and Reagan's support is significantly and positively related to their electoral success in that Senator's state for the years 1977 through 1988. Several control variables are included to help explain support. There is qualified corroboration for the hypothesis that senator's presidential support scores are significantly and positively related to the president's electoral success for specific administrations and for specific-party senators, although not for the original hypothesis that aggregated the period 1977 to 1988.
Date:
May 1994
Creator:
Endsley, Stephen C. (Stephen Craig)
System:
The UNT Digital Library
The impact of climate and flooding on tree ring growth of Fraxinus pennsylvanica in north-central Texas.
Tree cores of Fraxinus pennsylvanica were used in a dendrochronological analysis investigating the species' responses to climate and flooding. The objective was to develop a model that incorporates the effects of precipitation, temperature, and flooding on radial growth in this species in north-central Texas. The trees exhibited strong climatic signals. The study clearly shows that all three factors have significant impacts on tree ring growth both prior to and during growth; however, the nature and extent of these impacts are highly dependent on what time of year they occur. The large temporal variations in growth responses emphasize the importance of considering the timing of environmental events when studying tree growth responses.
Date:
December 2009
Creator:
Komperod, Mari
System:
The UNT Digital Library
The Influence of Stream Regulation on Genic Differentiation and Thermal Tolerance in the Red Shiner, Notropis Lutrensis
Genetic variation and thermal tolerance were surveyed for variation attributed to nonuniform selection pressures for five populations of the red shiner, Notropis lutrensis, collected from regulated and unregulated portions of a Texas river. Populations within 30 km of a hypolimnion-release dam that experience large thermal perturbations were found to have higher levels of heterozygosity, higher levels of polymorphism, significantly depressed levels of upper thermal tolerance endpoints, and greater variances in tolerance endpoints. These populations have evolved enzyme systems differing from the unregulated populations in response to a variable and depressed thermal regime.
Date:
December 1982
Creator:
King, Timothy L. (Timothy Lee)
System:
The UNT Digital Library
Discovery of Resources and Conflict in the Interstate System, 1816-2001
This study tests a theory detailing the increased likelihood of conflict following an initial resource discovery in the discovering nation and its region. A survey of prior literature shows a multitude of prior research concerning resources and nations' willingness to initiate conflict over those resources, but this prior research lacks any study concerning the effects of the discovery of resources on interstate conflict. The theory discusses the increased likelihood of conflict in the discovering nation as both target and initiator. It further looks at the increased chance of conflict in the discoverer's region due to security dilemmas and proxy wars. The results show strong support for the theory, suggesting nations making new resource discoveries must take extra care to avoid conflict.
Date:
May 2010
Creator:
Clark, Bradley
System:
The UNT Digital Library
Changes in Heterozygosity Through Time in American Standardbred and American Saddlebred Horses (1960-1990)
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-
System:
The UNT Digital Library
Evaluating Tree Seedling Survival and Growth in a Bottomland Old-field Site: Implications for Ecological Restoration
In order to assess the enhancement of seedling survival and growth during drought conditions, five-hundred bare-root seedlings each of Shumard oak (Quercus shumardii Buckl.) and green ash (Fraxinus pennsylvanica Marsh.) were planted each with four soil amendments at a Wildlife Management Area in Lewisville, Texas. The treatments were a mycorrhizal inoculant, mulch fabric, and two superabsorbent gels (TerraSorb® and DRiWATER®). Survival and growth measurements were assessed periodically for two years. Research was conducted on vegetation, soil, and site history for baseline data. Both superabsorbent gels gave significant results for Shumard oak survival, and one increased green ash diameter. For overall growth, significant results were found among DRiWATER®, mycorrhizae, and mulch treatments.
Date:
August 2007
Creator:
Boe, Brian Jeffrey
System:
The UNT Digital Library
Estimating Residential Water Demand: a Case of Multiple-Part Tariff for Denton, Texas
This paper analyzes the demand for water in case of a multiple-part tariff in Denton, Texas. The model used is developed from Billing & Agthe's model by using the following variables: marginal price, difference variable, tax assessed value, lot size, house size, temperature and rainfall.. The results indicate that temperature has the greatest effect on water demand, since this area is considered to be a very warm area. Also, marginal price seems to have a strong effect on water consumption indicating that customer is well-informed to a change in rate schedule. This test supports the original idea of the previous articles that the coefficient on difference variable and that on income should have the opposite sign. However, this test can not prove that those coefficients should be equal in magnitude, since the proxy of the income variable can not represent the individual monthly income. In addition, this article introduces another variable which can be a proxy of outdoor water use. That is lot size showing the effect on water demand. The last variable used in the model, house size,does not have much effect on water demand and is dropped out in the final model.
Date:
December 1986
Creator:
Wattanakuljarus, Voravit
System:
The UNT Digital Library
Investigation of the Pressure Dependence of SO3 Formation
The kinetics of the pressure dependent O + SO2 + Ar reaction have been investigated using laser photolysis resonance fluorescence at temperatures of 289 K, 399 K, 581 K, 699 K, 842 K and 1040 K and at pressures from 30-665 torr. Falloff was observed for the first time in the pressure dependence. Application of Lindemann theory yielded an Arrhenius expression of k(T) = 3.3 x 10-32exp(-992/T) cm6 molecule-1 s-1 for the low pressure limit and k(T) = 8.47 x 10-14exp(-468/T) cm3 molecule-1 s-1 for the high pressure limit at temperatures between 289 and 842 K. The reaction is unusual as it possesses a positive activation energy at low temperature, yet at higher temperatures the activation energy is negative, illustrating a reaction barrier.
Date:
December 2003
Creator:
Naidoo, Jacinth
System:
The UNT Digital Library
Sediment Bound Trace Metals in the White Rock Creek Watershed, Dallas and Collin Counties
Areas were sampled in the White Rock Creek Watershed to examine sediment bound trace metal distributions and sorption relationships. A Kruskal-Wallis AOV found significant among area differences for most metals, and SNK-like multiple comparisons were used to group these areas. Kruskal-Wallis AOVs similarly found among area differences for sediment components that bind trace metals (Fe and Mn oxides and organic carbon) and physicochemical conditions that influence metal sorption (particle size and pH). Multiple correlation found numerous relationships among trace metals, sediment components, and physicochemical conditions. Statistical relationships indicate that metal partitioning to various sorption factors is metal specific. White Rock Creek Watershed trace metal concentrations are comparable to those in many urban watersheds.
Date:
May 1990
Creator:
Combest, Kyle B. (Kyle Bryan)
System:
The UNT Digital Library
Development and Validation of a Ramping Treadmill Protocol for the On-Line Measurement of Four Aerobic Parameters
Previously, Whipp et. al. (J. Appl. Physiol.: Respirat. Environ. Exerc. Physiol. 50(1):217-221, 1981) demonstrated the feasibility of determining four parameters of aerobic function, identified as maximum oxygen uptake (μVO_2), VO_2 at anaerobic threshold (θan), the time constant for oxygen uptake kinetics (rVO_2) and work efficiency (η), using a short duration ramped bicycle ergometer exercise test. Because of the importance of being able to measure these parameters on a variety of measurement instruments a short duration ramping treadmill protocol has been developed. The ability of this protocol to determine the four aerobic parameters has been validated against conventional methods. The results of this investigation indicate that μVO_2, θan, rVO_2 and, η may be obtained from a single, short-duration ramping treadmill test.
Date:
May 1990
Creator:
Cowell, Lynda L. (Lynda Lea)
System:
The UNT Digital Library
Enkephalin Metabolism in Exercise Stress
Investigators have suggested that opiate peptide hormones released during exercise stress may play an important role in athletic performance or perceived effort. Their enzymatic inactivation in the periphery is of considerable interest since the opiate peptides may be regulated by enkephalin hydrolyzing enzyme (EHA). In this study, the relationship between maximal aerobic capacity (VO_2max) and EHA activity was examined in two distinct fitness groups. When the metabolic capacity was evaluated in whole blood, the unfit subjects metabolized the peptides significantly faster than their fit counterparts. Since the total enzyme activity of the two groups is similar, the difference in metabolism must result from circulating factors in the trained athletes, which slow the rate of peptide inactivation.
Date:
December 1984
Creator:
Jaskowski, Margaret Anne
System:
The UNT Digital Library
An Analysis of the Factors Which Distinguish Tennis Players of Different Serving Abilities
The purpose of this study was to examine selected mechanical factors involved in the tennis serve. Special emphasis was placed on identifying factors which distinguish players of different serving abilities. Ten right-handed female tennis players, five ranked, and five unranked, were evaluated, following filming with a high-speed camera, on the basis of five good and five fault serves. The ranked players were seen to differ from the unranked players with respect to (a) serving consistency, (b) initial Y-center of gravity values, (c) certain segment angles at the peak of the ball toss and at ball contact, and (d) certain joint angles at the moment of the ball contact.
Date:
August 1985
Creator:
Riley-Hagan, Margaret
System:
The UNT Digital Library
Atmospheric Visibility Assessment for Urban Areas Using Photographic Slides and Optical Densitometry
The factors involved in calculating Standard Visual Range (SVR) are discussed, and a comparison is made between the visibility reported by airport observers and the photographic slide/ optical densitometer method of calculating SVR. Using slides of Houston, Texas, from the fall and winter of 1988-89, it was found that the altitude at which the contrast measurements are made significantly affects the SVR. Also an index for predicting high and low humidity was developed using the blue/red ratio of the log exposure of the sky, and sun/shade target condition.
Date:
May 1992
Creator:
Jacob, Mary Katherine
System:
The UNT Digital Library
An Analysis of the Participant Selection Process Under the Comprehensive Employment and Training Act: Texas and Louisiana
Federal guidelines required prime sponsors under the Comprehensive Employment and Training Act, or CETA, to serve the "significant segments" of the eligible population. This study analyzes whether prime sponsors in Texas and Louisiana correctly identified and served those segments. This study finds that eligible ethnic groups were properly identified and were served equitably; age and gender distinctions, however, were inadequately observed in the providing of services.
Date:
May 1988
Creator:
Drake, William D. (William Daniel), 1950-
System:
The UNT Digital Library
Spatial and Temporal Patterns of Areal and Volumetric Phytoplankton Productivity of Lake Texoma
Phytoplankton productivity of Lake Texoma was measured for one year from August 1999 to August 2000 for four stations, using the oxygen change method and laboratory incubation. Mean values of the photosynthetic parameters, PBmax and alphaB ranged from 4.86 to 46.39 mg O2.mg Chl-1.hr-1 for PBmax and 20.06 to 98.96 mg O2.mg Chl-1.E-1.m2 for alphaB. These values were in the range to be expected for a highly turbid, temperate reservoir. Estimated gross annual areal productivity ranged from 594 g C.m2.yr-1 (P.Q. = 1.2), at a station in the Washita River Zone to 753 g C.m2.yr-1 at a station in the Red River Zone, of the reservoir. Gross annual areal productivity at Station 17, in the Main Lake Zone, was 708 g C.m2.yr-1. Gross areal and volumetric productivity showed distinct seasonal variation with Photosynthetically Available Radiation (PAR) and temperature. Trophic status estimated on a station-by-station basis, using net productivity values derived from gross productivity and respiration estimates, was mesotrophic for all the stations, though one station approached eutrophy. Net productivity values ranged from 0.74 to 0.91 g C. m-2.d-1. An algal bioassay conducted at two stations in August 2000, revealed that phosphorus was most likely the nutrient limiting photosynthesis at both …
Date:
August 2001
Creator:
Baugher, Tessy
System:
The UNT Digital Library
The Effect of Intermediate Filament Inhibitors on Steroidogenesis and Cytoskeleton in Y-1 Mouse Adrenal Tumor Cells
When Y-1 mouse adrenal tumor cells were treated with sodium orthovanadate, an intermediate filament (IF) inhibitor in BHK21-F cells, there was no change in the amount of 20α-dihydroprogesterone produced. A neurofilament inhibitor, β, β'-iminodipropionitrile (IDPN), enhanced the ability of Y-1 cells to produce steroid in response to ACTH by acting on the plasma membrane. Electron microscopy of Y-1 cells extracted with Triton X-100 revealed that both vanadate and IDPN caused the aggregation of cytoskeletal and granular structures in the perinuclear area. The steroidogenic effects of IDPN suggest that the perinuclear aggrergation of cytoskeletal structures may result from the detachment of IF from the plasma membrane, while the reason for the cytoskeletal changes by vanadate is unknown.
Date:
August 1982
Creator:
Lee, Hyun Sook
System:
The UNT Digital Library
Circulatory and Respiratory Responses to Cycle Ergometry at Different Pedal Rates
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
System:
The UNT Digital Library
A Kinematic Analysis of the Baseball Batting Swings Involved in Opposite-Field and Same-Field Hitting
The purpose of the study was to examine selected mechanical factors involved in hitting a baseball to the same and opposite fields. Special emphasis was placed on an identification of those factors which distinguish players of different hitting abilities. Twenty male college level baseball players, ten in each of two groups, hit six pitched baseballs, three each to two assigned areas of the playing field. The movement patterns for the opposite field and same field batting swings appeared to be similar in form with differences between the two swings due to (a) differences in the angular displacements at the left wrist and left elbow joints and (b) differences in the temporal characteristics.
Date:
December 1980
Creator:
Pfautsch, Eric W.
System:
The UNT Digital Library
Assessing the Effects of a Municipal Wastewater Treatment Plant Effluent on Zooplankton, Phytoplankton and Corbicula Flumina in a Constructed Wetland
Wetland wastewater treatment offers low-cost, energy efficient alternatives to conventional wastewater technologies. In this study, an artificial wetland was constructed at the City of Denton, Texas Pecan Creek Water Reclamation Plant to facilitate diazinon removal from treated effluent.
Date:
May 1995
Creator:
Hymel, Stephanie Ramick
System:
The UNT Digital Library
Macroinvertebrate Colonization and Assemblages Associated with Aquatic Macrophytes in a Newly Created Urban Floodway Ecosystem, Dallas, Tx
A study of macroinvertebrate colonization and assemblages, including secondary productivity of the familiar bluet damselfly or Enallagma civile Hagen (Odonata: Coenagrionidae), associated with the aquatic macrophytes Heteranthera dubia (Jacq.) MacMill. (water stargrass) and Potamogeton nodosus Poir. (American pondweed) was conducted at the Dallas Floodway Extension Trinity River Project (DFE) Lower Chain of Wetlands (LCOW), Dallas, TX, from September 2010 through November 2011. Macroinvertebrate abundance, taxa richness, Simpson's index of diversity, and Simpson's evenness from the two macrophytes and from three different wetland cells of varying construction completion dates, water sources, and native aquatic vegetation establishment were analyzed along with basic water quality metrics (temperature °C, pH, dissolved oxygen mg/L, and conductivity µs/cm). E. civile nymphs were separated into five developmental classes for secondary productivity estimations between macrophytes and wetland cell types. Mean annual secondary productivity in the DFE LCOW among two macrophytes of E. civile was 1392.90 ash-free dry weight mg/m²/yr, standing stock biomass was 136.77 AFDW mg/m2/yr, cohort production / biomass (P/B) ratio was calculated to be 4.30 / yr and the annual production / biomass (P/B) ratio was 10.18 /yr.
Date:
August 2013
Creator:
Schad, Aaron Neale
System:
The UNT Digital Library
Life History of Mayatrichia ponta Ross (Trichoptera: Hydroptilidae) in Honey Creek, Turner Falls Park, Oklahoma
The life history and ontogenetic microhabitat change of Mayatrichia ponta Ross were investigated in Honey Creek, Turner Falls Park, Murray Co., Oklahoma, U.S.A. from August 1994 to August 1995. The shape of larval cases changed from a small cone to a cylinder. M. ponta had an asynchronous multivoltine life history with considerable cohort and generation overlap; five generations were estimated. The development rate was reduced in winter. The winter generations of M. ponta had wider head capsule widths (136-165 μm) than summer generations (121-145 μm). The sex ratio of adults was 1.43 ♂ : 1 ♀. Fecundity ranged from 46 to 150 eggs/female. Fifth instar larvae and pupae aggregated on the bottom side of substrates. Early instars were distributed evenly on all sides of substrates. General patterns of ontogenetic microhabitat shift in aquatic insects are categorized as flow mediated, flow independent, and population interactions and other resources mediated.
Date:
December 1997
Creator:
Wang, Yi-Kuang
System:
The UNT Digital Library
Environmental Correlates to Genetic Variation in the Coral Reef Fish, Thalassoma bifasciatum
Genetic variation was examined in bluehead wrasse, Thalassoma bifasciatum, populations along the Florida Keys. Interpretion of mean heterozygosity (H), percent polymorphic loci per population (P), genetic similarity, and F and G statistics demonstrated a clear division of wrasse populations into "northern" and "southern" groups. Correlation and cluster analyses indicated the six reefs can be grouped in a similar fashion based on genetic and environmental data. The conclusion from this analysis of wrasse populations in the Florida Keys is that substantial population subdivision occurs in response to differing selective pressures created by heterogeneous environments.
Date:
December 1988
Creator:
Pirkle, Michelle S. (Michelle Serpas)
System:
The UNT Digital Library
Underwater Optical Properties of Lake Texoma (Oklahoma-Texas) Using Secchi Disk, Submarine Photometer, and High-Resolution Spectroscopy
The underwater optical climate of Lake Texoma was measured at eleven fixed stations from August 1996 to August 1997. Secchi transparency and submarine photometry characterized seasonal and spatial values of secchi depth (SD), vertical attenuation coefficient (η''), and depth of euphotic zone (Zeu). Indices of Zeu:SD and η'' × SD were compared with universally applied values derived from inland and coastal waters. Turbidity explained 76% of the variation (p = 0.0001) of η'' among water quality parameters, including chlorophyll-α. Using a spectroradiometer, spectral signatures of chlorophyll-α and turbidity were located. Stations with low turbidity exhibited a distinct green reflectance peak around 590-610 nanometers, indicating presence of chlorophyll-α. Stations with high turbidity exhibited a reflectance peak shift towards the red spectrum, making it difficult to detect the chlorophyll signature. Derivative analysis of the reflectance signal at 590-610, and 720-780 nanometers allowed discrimination of this chlorophyll signature from those of turbidity (0.66 ≤ r^2 ≤ 0.99).
Date:
August 1998
Creator:
Rolbiecki, David A. (David Alan)
System:
The UNT Digital Library