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887 Matching Results
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Life History and Case Building Behaviors of Phylloicus ornatus (Banks) (Trichoptera: Calamoceratidae) In Two Spring Fed Tributaries in the Central Edwards Plateau Bioregion of Texas
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The life history and case-making behaviors of Phylloicus ornatus from two springfed first order streams in the Edwards Plateau Bioregion of Texas were studied from January 1998 to November 1999. Field larval, pupal and adult samples and laboratory rearings indicated a multivoltine cycle. First instars differ from late instars in number of labral setae and in having a unique spur-like claw on each lateral hump. Larval development was asynchronous with second through fifth instars and pupae present most months. First instars were present April through July, October and November. Case making of first instar and case reconstruction of later instars extracted from their cases was documented by videophotography.
Date:
August 2000
Creator:
Norwood, James Christopher
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
The Interface of Personality Processes and Cognitive Abilities: A Comparative Study of Elderly and Young Adults
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Although research has shown that the complex constructs of intelligence and personality are necessarily intertwined, studies exploring this issue in elderly individuals are rare. The importance attached to this interface in older adults becomes particularly clear in light of the debate over the cause and extent of age-related decrements in cognitive performance as well as whether such losses can be ameliorated or not, especially given societal shifts toward increased life expectancies. The present study explored the basis for shifts in personality-ability relationships in adulthood by comparing two samples of older adults, one of which was assessed in 1975 (N = 102, M age = 68.4), and the second of which was assessed in 1995 (N = 100, M age = 72.0), and a sample of younger adults (N = 100, M age = 21.8), also assessed in 1995. Each participant was administered the Holtzman Inkblot Technique and the Gf-Gc Sampler, a measure of crystallized (Gc) and fluid (Gf) abilities. LISREL analyses of both age-related and historical shifts in personality-ability relationships suggested that not only were such shifts associated with cohort differences as reflected in factor loading (lambda) differences between the older samples and the younger sample, as well as between …
Date:
August 2000
Creator:
O'Brien, Dina Paige Ragow
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
A Data Fusion Framework for Floodplain Analysis using GIS and Remotely Sensed Data
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Throughout history floods have been part of the human experience. They are recurring phenomena that form a necessary and enduring feature of all river basin and lowland coastal systems. In an average year, they benefit millions of people who depend on them. In the more developed countries, major floods can be the largest cause of economic losses from natural disasters, and are also a major cause of disaster-related deaths in the less developed countries. Flood disaster mitigation research was conducted to determine how remotely sensed data can effectively be used to produce accurate flood plain maps (FPMs), and to identify/quantify the sources of error associated with such data. Differences were analyzed between flood maps produced by an automated remote sensing analysis tailored to the available satellite remote sensing datasets (rFPM), the 100-year flooded areas "predicted" by the Flood Insurance Rate Maps, and FPMs based on DEM and hydrological data (aFPM). Landuse/landcover was also examined to determine its influence on rFPM errors. These errors were identified and the results were integrated in a GIS to minimize landuse / landcover effects. Two substantial flood events were analyzed. These events were selected because of their similar characteristics (i.e., the existence of FIRM or …
Date:
August 2000
Creator:
Necsoiu, Dorel Marius
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Dallas Area Health Care Use: Study of Insured, Uninsured, and Medicaid Enrolled Children
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This research investigated physician and emergency room use among representative samples of children in the Dallas metropolitan area (N = 1606) and among patients who used Children's Medical Center of Dallas' First Care services (N = 612). Through telephone interviewing, caregivers to children under fifteen years of age were asked about an array of health service use behaviors, social-psychological issues related to acquiring health care for their children, and demographic characteristics as outlined by the Andersen & Newman model of health care service use. Children's use of physician services is best predicted by whether or not they have medical insurance, their level of income, and whether or not they have medical homes. Although having commercial managed care and fee-for-service Medicaid insurance consistently predicted increased physician use, neither independently reduced reliance on emergency rooms for non-emergent care. Managed care insurance and Medicaid did, however, significantly improve the odds that children would have medical homes, which significantly decreased emergency room use for non-emergent care. Further, increasing physician use and reducing reliance on hospital emergency rooms for non-emergent care will require ensuring that children have medical homeseither private physicians or community health centersat which they can readily and consistently receive sick and well …
Date:
August 2000
Creator:
Roy, Lonnie C.
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Production and Characterization of a Novel Extracellular Polysaccharide Produced by Paenibacillus velaei, Sp. Nov
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Paenibacillus velaei, sp. nov. is a soil bacterium capable of producing an unusually large amount of exopolysaccharide (EPS). The EPS contains glucose, mannose, galactose and fucose in a molar ratio of 4:2:1:1. The molecular weight of the EPS is higher than 2x106. The viscosity of 1% EPS is 1300 cP when measured at a shear rate of 1 sec-1. Physiological parameters for optimal production of the EPS were studied and it was found that 1.4 g dry weight per 1 l of medium was produced when the bacteria were grown at 30EC and the pH adjusted at 7± 0.2 in a medium containing glucose as the carbon source. Growing the bacteria on different carbon sources did not alter the quantity or the composition of the EPS produced. No toxicity effects were observed in mice or rats when EPS was administered in amounts ranging from 20 to 200 mg per kg body weight. The data obtained from physical, chemical and biological properties suggest that the EPS may be employed in several industrial and environmental applications. It is an excellent emulsifier, it holds 100 times its own weight in water, it is not toxic, and it can be used to remove mercury, …
Date:
August 2000
Creator:
Sukplang, Patamaporn
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Maintaining behavior in a child with autism using a previously neutral stimulus, a remote control tactile stimulus, as the consequence
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Few studies have investigated methods for establishing neutral stimuli as conditioned reinforcers in human subjects. Conditioned reinforcers, however, can alleviate some of the problems encountered in applied behavior analytic (ABA) therapy for children with autism, such as satiation and suitability of reinforcers for specific environments. A series of reversals evaluated the effects of a conditioning procedure involving pairing a neutral stimulus, the remote control stimulus (RCT), with an identified reinforcer. Phase 1 demonstrated that the RCT was neutral. In Phase 2, alternating pairing and testing conditions were run. During testing the effects of pairing were evaluated by the effectiveness of the RCT in maintaining a response in the absence of a previously available reinforcer (extinction test) and in increasing a new response over a baseline level (learning test). Results from the extinction test suggest that under some pairing conditions the RCT can acquire properties of a reinforcer.
Date:
August 2000
Creator:
Wheat, Leigh Ann Stiles
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Substituent Effects: A Computational Study on Stabilities of Cumulenes and Low Barrier Hydrogen Bonds
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The effect of substituents on the stabilities of cumulenes-ketenes, allenes, diazomethanes and isocyanates and related systems-alkynes, nitriles and nitrile oxides is studied using the density functional theory (B3LYP, SVWN and BP86) and ab initio (HF, MP2) calculations at the 6-31G* basis set level. Using isodesmic reactions, correlation between stabilization energies of cumulenes and substituent group electronegativities (c BE) is established and the results from DFT and MP2 methods are compared with the earlier HF calculations. Calculations revealed that the density functional methods can be used to study the effect of substituents on the stabilities of cumulenes. It is observed that the cumulenes are stabilized by electropositive substituent groups from s -electron donation and p -electron withdrawal and are destabilized by electronegative substituent groups from n-p donation. The calculated geometries of the cumulenes are compared with the available experimental data.High level ab initio and density functional theory calculations have been used to study the energetics of low-barrier hydrogen bond (LBHB) systems. Using substituted formic acid-formate anion complexes as model LBHB systems, hydrogen bond strength is correlated to the pKa mismatch between the hydrogen bond donor and the hydrogen bond acceptor. LBHB model systems are characterized by the 1H-NMR chemical shift calculations. …
Date:
August 2000
Creator:
Kumar, Ganesh Angusamy
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
The Apologist Tradition: A Transitional Period in Southern Proslavery Thought, 1831-1845
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Early antebellum defenders of slavery acknowledged that slavery created problems for southern society. They contended, however, that slave society was better and more natural than other forms of social organization. Thomas R. Dew, William Harper, and James Henry Hammond each expressed a social philosophy in which slavery had a crucial role in preserving social order. They argued from the basis of social organicism, the idea that society should have an elite that controlled the masses. For all three men, slavery represented a system of order that helped balance the dangers of democracy. Significantly, however, all three men recognized that the slave system was not perfect, and despite their defense of slavery, argued that it was a human institution and therefore corruptible.
Date:
December 2000
Creator:
Austin, Clara
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Logic Programming Tools for Dynamic Content Generation and Internet Data Mining
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The phenomenal growth of Information Technology requires us to elicit, store and maintain huge volumes of data. Analyzing this data for various purposes is becoming increasingly important. Data mining consists of applying data analysis and discovery algorithms that under acceptable computational efficiency limitations, produce a particular enumeration of patterns over the data. We present two techniques based on using Logic programming tools for data mining. Data mining analyzes data by extracting patterns which describe its structure and discovers co-relations in the form of rules. We distinguish analysis methods as visual and non-visual and present one application of each. We explain that our focus on the field of Logic Programming makes some of the very complex tasks related to Web based data mining and dynamic content generation, simple and easy to implement in a uniform framework.
Date:
December 2000
Creator:
Gupta, Anima
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Factors Affecting Household Disaster Preparedness: A Study of the Canadian Context
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This study addresses the issue of household disaster preparedness. This work contributes two elements to disaster research. The first contribution improve the knowledge of the factors that affect household disaster preparedness. The review of literature yielded three categories of variables that can jointly explain household disaster preparedness: household structure, demographics, and risk-perception factors. In this study 19 variables compose these factors. A second contribution constitutes a theoretical exploration of the concept of disaster preparedness. In this work, four different constructs of disaster preparedness were tested. These constructs include material preparedness, preparedness activities, a combined index, and a weighted and combined index. The study presents the logic and methodology of the index construction and validation. The data used in this study came from households in the Montreal Urban Community (MUC) in Canada. A random sample of 1,003 English- and French-speaking heads of households adequately represents the 1.8 million persons within the MUC. An independent survey firm conducted the interviews in 1996. Results show that the weighted combined household disaster preparedness index constitutes the best construct to represent the concepts under study. Study results also reveal that risk-perception variables (attitudinal factors) offered the strongest explanatory power. Household structure and demographic variables collectively …
Date:
December 2000
Creator:
Doré, Michel C
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
The Effect of Attachment on Preschooler's Emotion Understanding
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The purpose of this study was to identify the relationship between attachment and emotion understanding in preschoolers. Data was collected from 16 preschool children and their mothers recruited from a private learning center in a downtown metropolitan area. Attachment was measured by use of the Attachment Q-sort, 3.0 (Waters, 1995), while emotion understanding was assessed through use of Denham's (1986) affective perspective-taking task and interviews of children concerning naturally occurring emotions and emotion causes (Fabes et al., 1991). Results included a significant correlation (p < .05) between secure attachment and preschooler's ability to decipher the cause of another's emotion; however, a significant correlation was not found between secure attachment and preschooler's perspective-taking ability or ability to name other's emotions. Thus, conclusions about the impact of attachment upon emotion understanding were mixed, and more research on the subject was implicated.
Date:
December 2000
Creator:
Hernandez, Jennie R.
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Sarah T. Hughes: Her Influence in Texas Politics
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Conservative males traditionally dominated Texas politics. In 1930, however, Sarah T. Hughes, a liberal woman from Maryland, began a spectacular career in state politics despite obstacles because of her gender and progressive ideas. First elected to the Texas Legislature in 1930, she remained active in politics for the next fifty years. Hard work, intelligence, and ability allowed her to form solid friendships with Texas's most powerful politicians. She became the first woman in Texas to hold a district judgeship, the first woman from Texas appointed to the federal bench, and the only woman to swear in a U.S. president. Hughes profoundly influenced state politics, challenging the long-standing conservative male domination. She helped to create a more diverse political field that today encompasses different ideologies and both genders.
Date:
December 2000
Creator:
Justiss, Charnita Spring
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Alternative Information Processing Formats for Overcoming Information Processing Deficits in Senior Adults
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The objective of this study was to examine the effectiveness of alternative advertising presentation formats, and the quantity of information presented in advertisements in overcoming possible information-processing deficits in senior adults that could affect their recall of ad attributes and brand name, the cognitive responses generated, and attitude toward the ad. In addition, the study examined the effectiveness of retirement status as a classification or segmentation variable in comparison with the use of the more traditional classification variable, chronological age. A convenience sample of senior adult volunteers from church groups, social clubs, and civic organizations from the local area were randomly assigned to one of nine experimental conditions. The experiment utilized a simulated magazine to test the effects of presentation formats (3 levels), and quantity of information (3 levels) on senior adult's recall, cognitive responses and attitude toward the test ads. Covariates (gender, wealth, education, activity level, health, and income) were used to reduce variance. The findings clearly indicate that the presentation format of the can ad adversely affected the memory of some senior adults. In addition, the results were significantly different across the different age levels. Retirement status was less beneficial than chronological age in the current study, but …
Date:
December 2000
Creator:
Muller, Lynn F.
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Effects of Reinforcement History on Stimulus Control Relations
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Ray (1969) conducted an experiment on multiple stimulus-response relations and selective attention. Ray's (1969) results suggested that stimulus-response relations function as behavioral units. McIlvane and Dube (1996) indicated that if stimulus-response relations are behavioral units the effects of environmental variables on stimulus-response relations should be similar to the effects of environmental variables on single response topographies. This experiment analyzed the effects of reinforcement history on the probability of stimulus-response relations with differing reinforcement histories. In separate conditions random-ratio schedules of reinforcement were contingent on each of four discriminated responses. To assess the effects of reinforcement, during test conditions stimuli controlling different topographies were present concurrently in composite form. Results show that reinforcement history affects the probability of each response topography and that the association between response topographies and their controlling stimuli tends to remain constant throughout variations in reinforcement probability.
Date:
December 2000
Creator:
Reyes, Fredy
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Effect of Engineered Surfaces on Valve Performance
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Performance of air operated valves is a major maintenance concern in process industries. Anecdotal information indicates that reliability of some high maintenance valves has been improved by using an ion deposition process to achieve engineered surfaces on selected components. This project compared friction for various surface treatments of selected valve components. Results indicate valve performance may be slightly more consistent when an engineered surface is applied in the valve packing area; however surface treatment in this area does not appear to have a dominant affect on reducing valve friction. Results indicate a linear relation between stem friction and torque applied to packing flange nuts, and even after a valve is in service, controlled packing adjustments can be made without significantly changing valve stroke time.
Date:
December 2000
Creator:
Pope, Larry G.
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Bird Bones and a Hatched Egg
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A fifty page manuscript of poetry and a critical introduction detailing the poet's aesthetics. Using the idea of the double-image and eroticism, the poet places her work in the category of the surreal. She describes the process of writing poetry born of fragmentary elements as a feminist emergence of agency. The manuscript is composed of four sections, each an element in the inevitable breakdown of a love relationship: meeting, love-making, birth of a child, death. Quotes from various authors of anthropological and fictional texts begin each section to reinforce thematic structure in a process of unveiling the agency of the narrator. The poems are organized as a series, beginning and ending with sequence poems.
Date:
December 2000
Creator:
Skebe, Carolyn Alifair
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Academic Dishonesty: Attitudes and Behaviors of Fundamentalist Christian College Students
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This study was designed to examine: (1) the extent to which cheating occurs in fundamentalist Christian colleges; (2) the attitudes of fundamentalist Christian college students toward cheating; (3) attitudes of fundamentalist Christian college students toward cheating among their peers; (4) the kinds of cheating practices of fundamentalist Christian college students; (5) the degree to which students engage in neutralizing behavior to justify cheating; (6) differences in cheating behaviors according to gender; (7) differences in cheating behaviors according to ethnicity; and (8) differences in cheating behaviors according to the length of duration of Christian commitment. Based upon the responses of 337 students attending 3 different Christian colleges, it was concluded that: (1) most Christian fundamentalist students do not engage in cheating; (2) respondents believe that each of 17 self-reported cheating behaviors are serious forms of cheating; (3) respondents are unlikely to report cheating among peers; (4) plagiarism is the most common cheating behavior; (5) most respondents justify cheating on the basis of the workload at school and the pressure to obtain good grades; (6) there are no differences in cheating behavior according to gender; (7) there are differences in cheating behavior according to groups; and (8) most respondents do not cheat …
Date:
December 2000
Creator:
Sunday, William G.
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Diphosphine Ligand Activation Studies with Organotransition-Metal Compounds
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Thermolysis of CoRu(CO)7(m -PPh2) (1) in refluxing 1,2-dichloroethane in the presence of the diphosphine ligands 2,3-bis(diphenylphosphino)maleic anhydride (bma) and 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) furnishes the new mixed-metal complexes CoRu(CO)4(μ -P-P)(μ -PPh2) [where P-P = bma (3); bpcd (6)], along with trace amounts of the known complex CoRu(CO)6(PPh3)(μ -PPh2) (4). The requisite pentacarbonyl intermediates CoRu(CO)5(μ -P-P)(μ -PPh2) [where P-P = bma (2); bpcd (5)] have been prepared by separate routes and studied for their conversion to CoRu(CO)4(μ -P-P)(μ -PPh2). The complexes 2/3 and 5/6 have been isolated and fully characterized in solution by IR and NMR spectroscopy. The kinetics for the conversion of 2→3 and of 5→6 were measured by IR spectroscopy in chlorobenzene solvent. On the basis of the first-order rate constants, CO inhibition, and the activation parameters, a mechanism involving dissociative CO loss as the rate-limiting step is proposed. The solid-state structure of CoRu(CO)4(μ -bma)(μ -PPh2) (3) reveals that the two PPh2 groups are bound to the ruthenium center while the maleic anhydride π bond is coordinated to the cobalt atom. Thermolysis of the cluster Ru3(CO)12 with the bis(phosphine)hydrazine ligand (MeO)2PN(Me)N(Me)P(OMe)2 (dmpdmh) in toluene at 75°C furnishes the known clusters Ru4(CO)12[μ -N(Me)N(Me)] (9) and Ru3(CO)11[P(OMe)3] (10), in addition to the new …
Date:
December 2000
Creator:
Wang, Jiancheng
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Work in the calling in Max Weber's Protestant ethic thesis
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Objectives. Scholars have debated Max Weber's theory of the relationship between religion and capitalism for almost 100 years. Still, the debate is clouded by confusion over Weber's claims about religious doctrine and over the supporting evidence. The purpose of this study is to clarify Max Weber's claims regarding the concept of the calling and the related "anti-mammon" injunction and concept of "good works" and substantiate with historical evidence the religious doctrine Weber describes. Methods. Comparative analysis of early Protestant Lutheran and Calvinist documents from the sixteenth and seventeenth centuries was used to flesh out a history of ideas to determine whether evidence exists to support Weber's claims related to religious doctrine. Results. Historical analyses revealed that the concept of the calling pre-dated Luther in the Bible. Luther's innovation was not in his use of the word beruf but in his application of the concept of the calling to the common people and his teaching of that idea. The idea of sanctified work was key in both Lutheran and Calvinist documents. There was an increased emphasis on work and encouragement to accumulate wealth in Calvinist documents. Conclusion. Weber's etymological evidence surrounding Martin Luther's use of the word beruf in his German …
Date:
December 2000
Creator:
Schindley, Wanda Beatrice Higbee
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Juvenile Justice Sentencing: Are There Alternatives?
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Research indicates that states have implemented juvenile justice reforms to enact harsher punishments, to transfer greater numbers and younger juvenile offenders to adult criminal court, and to restrict discretion of the juvenile court judges. Social science studies have found that harsher punishments, transfers to adult criminal court and other measures do not work, but that comprehensive approaches which address the numerous major factors contributing to juvenile offending have been successful. This study examined the legal status of the juvenile justice system by focusing upon ten diverse sample states and analyzed the social science research on factors contributing to juvenile offending and on prevention, treatment, and rehabilitation approaches. The study was accomplished by legal research, qualitative social science research, and analysis of both. Findings indicated: a) state statutes require and allow adult punishment of juvenile offenders, transfer of juvenile offenders to adult criminal court, and direct filing of charges against juveniles in adult criminal court; most states begin these proceedings at age 14, some have no age minimum; b) social science research indicates numerous factors contribute to juvenile offending with most of the factors categorized into the major factors of early antisocial behavior, deviant peers, parents and family, sociomoral reasoning, biological …
Date:
December 2000
Creator:
Youngblood, Michelle K.
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
A model for designing a new telecommunication system in Mongolia
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The objective of this research is to design, and determine the feasibility of, a telecommunication system for the city of Erdenet, Mongolia. The Mongolian Telecommunication Company, Telecommunication Company of Erdenet city, and the National Statistical Office of Mongolia provided the data required for telecommunication forecasting of Erdenet. The literature review and analysis of the telecommunication forecasting indicate the need for a model of a new Telecommunication system in Erdenet, Mongolia. The model, as indicated, should become a useful example for planning and updating the telecommunication system in Mongolia. The design of a proposed telecommunication network involves the following considerations: analyzing and forecasting telephone traffic, calculating the required number of channels, determining exchange locations, traffic matrix, and establishing a basic hierarchical structure.
Date:
May 2001
Creator:
Baatarjav, Enkhbat
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Layered Double Hydroxides and the Origins of Life on Earth
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A brief introduction to the current state of research in the Origins of Life field is given in Part I of this work. Part II covers original research performed by the author and co-workers. Layered Double Hydroxide (LDH) systems are anion-exchanging clays that have the general formula M(II)xM(III)(OH)(2x+2)Y, where M(II) and M(III) are any divalent and trivalent metals, respectively. Y can be nearly any anion, although modern naturally occuring LDH systems incorporate carbonate (CO32-), chloride (Cl-), or sulfate (SO42-) anions. Intercalated cobalticyanide anion shows a small yet observable deviation from local Oh symmetry causing small differences between its oriented and non-oriented infrared spectra. Nitroprusside is shown to intercalate into 2:1 Mg:Al LDH with decomposition to form intercalated ferrocyanide and nitrosyl groups of an unidentified nature. The [Ru(CN)6]4- anion is shown to intercalate into layered double hydroxides in the same manner as other hexacyano anions, such as ferrocyanide and cobalticyanide, with its three-fold rotational axis perpendicular to the hydroxide sheets. The square-planar tetracyano-nickelate(II), -palladate(II), and platinate(II) anions were intercalated into both 2:1 and 3:1 Mg:Al layered double hydroxides (LDH). The basal spacings in the 2:1 hosts are approximately 11 Å, indicating that the anions are inclined approximately 75 degrees relative to …
Date:
May 2001
Creator:
Brister, Brian
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
A preliminary study on the effect of selective serotonin reuptake inhibitors on peripheral and lower brainstem auditory processing.
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This study compared auditory behavioral and physiologic measures in normal control subjects and subjects prescribed with a selective serotonin reuptake inhibitor (SSRI) who were yet to take the drug and those currently taking an SSRI. Test measures used were pure tone averages (PTA), acoustic reflex thresholds, uncomfortable loudness levels (UCL), otoacoustic emissions, masking level difference, temporal integration, amplitude resolution, and Beck Depression Inventory-II (BDI-II) scores. Results indicated that there was a significant difference in the amplitude resolution of the unmedicated group when compared to the medicated and the control group. There was also a significant positive correlation between dynamic range (difference between UCL and PTA) and amplitude resolution. The BDI-II revealed a significant difference between the scores of the unmedicated and the control group as well as the medicated and the control group. Although other test measures indicated differences between the groups, the differences were not statistically significant.
Date:
May 2001
Creator:
Carney, Lara E.
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Development of a Procedure to Evaluate Groundwater Quality and Potential Sources of Contamination in the East Texas Basin
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This study contributes a procedure, based on data analysis and geostatistical methods, to evaluate the distribution of chemical ratios and differentiate natural and anthropogenic contaminant sources of groundwater quality in the East Texas Basin. Four aquifers were studied, Sparta, Queen City, Carrizo and Wilcox. In this study, Carrizo- Wilcox is considered as one aquifer, and Sparta-Queen City as another. These aquifers were divided into depth categories, 0-150 feet for Sparta-Queen City and 300-600 feet and 600-900 feet for Carrizo-Wilcox in order to identify individual sources of contamination. Natural sources include aquifer mineral make up, salt domes and lignite beds. Major anthropogenic sources include lignite and salt dome mining and oil-gas production. Chemical ratios selected were Na/Cl, Ca/Cl, Mg/Cl, SO4/Cl, (Na+Cl)/TDS, SO4/Ca and (Ca+Mg)/(Na+K). Ratio distributions and their relationships were examined to evaluate physical-chemical processes occurring in the study area. Potential contaminant sources were used to divide the Basin into three areas: Area 1 to the east, Area 2 in the west and Area 3 in the center. Bivariate analysis was used to uncover differences between the areas. The waters in Area 1 are potentially impacted primarily from oil field waters. Sources present in Area 2 include lignite beds and oil …
Date:
May 2001
Creator:
Alderman, John H.
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library