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1,454 Matching Results
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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
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.
System:
The UNT Digital Library
A preliminary study of the effects of selective-serotonin re-uptake inhibitors (SSRIs) on central auditory processing
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his study compared auditory behavioral and physiological measures among three subject groups: 1) Normal control subjects, 2) subjects who were on a prescribed SSRI for depression, and 3) subjects who were prescribed an SSRI for depression, but were not medicated at the time of testing. Test measures included: Standard audiological tests (audiometry and tympanometry), electrophysiological procedures for analysis of auditory- evoked brainstem and late responses, and standardized behavioral speech tests (SCAN-A, SSI, and the low predictability sentence list of the R-SPIN). Analysis of results indicated a statistically significant increase of group mean amplitude of the ABR peak V, from 15dBnSL to 55dBnSL, in the non-medicated group compared to controls. Also, the non-medicated group scored significantly less favorably than controls on the most challenging listening condition (-20 MCR) of the SSI, in the left ear. Although other test measures indicated consistent differences between these two groups, they were not, however, significant.
Date:
August 2001
Creator:
Bishop, Charles E.
System:
The UNT Digital Library
Barriers Limiting Access to Hospice Care for Elderly African Americans in Amarillo, Texas
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This study examines barriers limiting access to hospice care for elderly African Americans. Ethnic background plays a critical role in the development of attitudes, beliefs and expectations related to death and issues surrounding hospice care. The purpose of this study was to identify barriers that may limit access to hospice care for African Americans. A questionnaire was administered to 56 elderly African Americans in three religious settings and an African American senior citizens center. The questionnaire was designed to obtain information concerning African Americans' attitudes toward death and dying; religious beliefs; health beliefs; familiarity with hospice and prospective use of hospice. The results of the study indicate a number of barriers in access to hospice care for African Americans including: hospice knowledge barriers; education/outreach barriers; cultural knowledge barriers related to death/dying values; family/social support barriers; hospice organizational/provider barriers; health care organizational/provider barriers; and reimbursement barriers.
Date:
August 2001
Creator:
Anthony, Tomagene
System:
The UNT Digital Library
Problems Encountered in Money Laundering Investigations
The purpose of this study is to identify how the U.S. is responding to money laundering and what kind of problems arise while countering it, beginning with a detailed description of money laundering, its stages, typologies, impacts, and complications. Due to the broad nature of this subject only three main issues form the focal point of this study: problems concerning the banking industry and other financial organizations, problems resulting from the limitations of law enforcement agencies, and problems arising from the lack of cooperation between and within financial institutions and law enforcement agencies. Several probable solutions to the above problems are identified: Considering the financial industry, there are loopholes in the Bank Secrecy Act (BSA) and in other regulations that apply to the industry. Thus, there is a comparison of the Subjective Model vs. Objective Model in terms of reporting systems for financial organizations. On the law enforcement side, the priority is the need to update and upgrade their technology and investigation mechanisms in order not to fall behind the criminals. Finally, cooperation is something that can be achieved through mutual respect and understanding of the priorities of each side, which can be achieved by the creation of an upper …
Date:
August 2001
Creator:
Akyay, Ilkay
System:
The UNT Digital Library
Texas Annexation and the Presidential Election of 1844 in the Richmond, Virginia, and New Orleans, Louisiana, Newspaper
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This thesis examines the issue of Texas annexation from the viewpoints of two southern cities: Richmond, Virginia, and New Orleans, Louisiana. It looks primarily at four major newspapers, two in each city: the Richmond Enquirer and the Richmond Whig; and the New Orleans Times-Picayune and the New Orleans Whig. These four newspapers were examined thoroughly from January 1844 to July 1845. In addition to the above newspapers, the Congressional Globe and national voting patterns on Texas annexation were examined. Analysis of the editorial articles in the above newspapers offers the best possibility of understanding public sentiment toward Texas annexation and the presidential election of 1844. The evidence examined in this study indicates that Texas annexation became a decisive issue in the presidential election of 1844. It also shows that, although the press and elements within both Democratic and Whig parties were aware that the slavery question was intricately linked to the Texas annexation issue, slavery and sectional politics were not the primary factors influencing annexation. Ultimately, fundamental concerns regarding western expansion in general, especially for the Whigs, and political party loyalty proved the decisive factors in the presidential election of 1844 and Texas annexation. The evidence gathered in this study …
Date:
December 2001
Creator:
Short, Steven W.
System:
The UNT Digital Library
Characterizaton of Triethoxyfluorosilane and Tetraethoxysilane Based Aerogels
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Aerogels are highly porous, low dielectric constant (low k) materials being considered by the semiconductor industry as an interlayer dielectric. Low k materials are needed to overcome capacitance problems that limit device feature sizes. Precursors triethoxyfluorosilane (TEFS) and tetraethoxysilane (TEOS) were used to prepare bulk aerogels. Samples were prepared by sol-gel methods, and then carbon dioxide supercritically-dried. Effects of varying the water to precursor ratio were studied with respect to aerogel properties and microstructure. Methods of analysis for this study include FTIR-ATR, TEM, RBS, EDS, SEM, dielectric constant determination by impedance and surface area by gas adsorption. Si-F bonds were determined to be present in both acid- and base-catalyzed TEFS as well as HF-catalyzed TEOS. Fluorine promotes a fractal network microstructure as opposed to a particle-like microstructure. Surface area and dielectric constant were determined to increase slightly with increases in the water to precursor ratio.
Date:
December 2001
Creator:
Roepsch, Jodi Ann
System:
The UNT Digital Library
Immediate and subsequent effects of fixed-time food presentations on automatically maintained mouthing.
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Several studies have demonstrated that fixed-time (FT) schedules of stimulus delivery can function to reduce a variety of behaviors. The purpose of this study was to evaluate the immediate and subsequent effects of FT food deliveries on mouthing. In Phase 1, a preference assessment showed that caramel popcorn, chocolate cookies and pretzels were highly preferred food items. Thus, providing the basis for use of food items during treatment. In Phase 2, a functional analysis showed that mouthing was a nonsocially maintained problem behavior. Phase 3 demonstrated the use of FT schedules of food deliveries as treatment for nonsocially maintained mouthing. Results indicated that FT schedules of food significantly reduced mouthing. In addition, levels of mouthing observed during post-FT observations were reliably lower than pre-FT observations. Treatment effects, operative mechanisms responsible for the treatment effects and the experimental arrangement used to investigate varying FT schedules are discussed.
Date:
December 2001
Creator:
Simmons, Jason N.
System:
The UNT Digital Library
Microwave Cavity Test for Superconductivity
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The first part of this paper describes the Meissner effect in superconductors which serves as the most definitive evidence for superconductivity. It is shown that the microwave perturbation technique may be used to demonstrate this effect. By measuring the changes of resonant frequency and inverse quality factor Q of a microwave cavity with a small volume of sample loading, the Meissner effect can be shown by using the Slater perturbation equation. The experimental system is described with details and the basic principle of each component discussed. The second part of this work describes the technique employed to do the actual measurements. The experiments were conducted on samples of Gallium Arsenide (GaAs) and lead zirconate titanate (PZT) to look for the possible high temperature superconductivity properties. Results of these experiments are presented and discussed. Conclusion and suggestions to future exploration are made.
Date:
December 2001
Creator:
Tang, Shan
System:
The UNT Digital Library
Mineral-filled polypropylene: Improvement of scratch resistance
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A potential alternative to acrylonitrile-butadiene-styrene (ABS) and polycarbonate+ABS (PC+ABS), pigmented mineral-filled polypropylene (PP) finds an opening in automotive interior components such as instrument panels, knee bolsters, consoles, etc. Because of the lack of surface aesthetics, pigmented mineral-filled PP is experiencing a limitation to its acceptance in many applications. This study focuses on exploring various mineral fillers and additives in polypropylene to provide a material with enhanced scratch resistance. Several physical properties including Rockwell and Shore D hardness are investigated, and it is determined that Filler W improves scratch resistance. It is also determined that Filler T-filled-PP has poor scratch resistance even with the addition of a lubricant.
Date:
December 2001
Creator:
Khatib, Jamal F.
System:
The UNT Digital Library
The preparation and characterization of thermo-sensitive colored hydrogel film and surfactant-free porous polystyrene three-dimensional network.
Polymer hydrogel films change their properties in response to environmental change. This remarkable phenomenon results in many potential applications of polymer hydrogel films. In this thesis colored thermo-sensitive poly(N-isopropylacrylamide) (PNIPAAm) hydrogel film was prepared by firstly synthesizing polymer latex and secondarily crosslinking the nanoparticles and casting the polymers onto glass. The shape-memory effect has been observed when changing the environmental temperature. The temperature-dependent of turbidity of polymer hydrogel film was measured by HP UVVisible spectrophotometer. This intelligent hydrogel might be used in chemomechanical systems and separation devices as well as sensors. Polymer adsorption plays an important role in many products and processes. In this thesis, surfactant-free three-dimensional polystyrene (PS) nanoparticle network has been prepared. The infrared spectroscopy and solubility experiment are performed to prove the crosslinking mechanism, also the BET method was used to measure the adsorption and desorption of polystyrene network. The BET constant (C) is calculated (C=6.32). The chemically bonded polymer nanoparticle network might have potential applications as catalyst or used for chromatographic columns.
Date:
December 2001
Creator:
Zhou, Bo
System:
The UNT Digital Library
Signs and Cases
Abstract not available
Date:
December 2001
Creator:
Whitmire, James
System:
The UNT Digital Library
The Effects of Graduated Exposure, Modeling, and Contingent Social Attention on Tolerance to Skin Care Products with Children Who Have Autism.
The effects of graduated exposure, modeling and contingent social attention on tolerance to skincare products were evaluated with two boys with autism who displayed tactile defensiveness. Upon each presentation step of skincare products the number of positive and negative responses and successful step completion were measured. Procedures included modeling, presenting graduated opportunities, and providing social attention for step completion. Step advancement occurred if a child engaged in a step independently, without excessive refusals. A changing criterion design and a multiple baseline were employed to evaluate effects of this treatment package. Children demonstrated more positive and fewer negative responses as they completed the graduated steps. Effects maintained in follow-up observations.
Date:
December 2001
Creator:
South, Ellyn M.
System:
The UNT Digital Library
The Effect of Punishment Threat on Children's Ability to Resist Temptation to Transgress and Lie
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Children's response to a resistance-to-temptation (RTT) task was investigated under three punishment threat conditions: negative consequence, removing an anticipated reward, and no explicit punishment. Ninety first and second graders participated in the RTT task and seventy-three parents completed the Behavior Assessment System for Children and the Psychopathy Screening Device. As only 4% of children transgressed, results are unclear. Hypotheses tested using approximations of transgression showed no differences in RTT. Children with temperaments characterized by hyperactivity, impulsivity, attention problems, and conduct problems (HIA-CP) had the highest levels of psychopathic traits compared to all others. In addition, spanked children were rated as having significantly more behavioral problems than non-spanked children. Limitations of the current study and suggestions for future research are discussed.
Date:
December 2001
Creator:
Collins, Michelle
System:
The UNT Digital Library
A laboratory course in experimental genetics for the biology major.
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This manual has been designed for a class of twenty- four students concurrently enrolled in the lecture course. The laboratory aids in the learning process and fosters an interest in the science of genetics. This manual and the experiments contained within are both informative and fun. The manual correlates with and expands upon the genetics course. Each investigation, with the exception of the Drosophila melanogaster project, can be completed in a 3-4 hour timeframe. This manual provides a “hands on” experience of theories simply discussed in the lecture course. This manual is intended to be a one-source manual where each investigation is designed to include an adequate introduction. Special attention has been given for each investigation with both the student and instructor in mind.
Date:
December 2001
Creator:
Lux, Melissa McNeil
System:
The UNT Digital Library
The Effects of Color Concentrate in Polyolefins.
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Throughout history consumer products were generally manufactured from wood and metal. They either had to hold their natural color or become subject to painting. When plastics entered the industry, it was recognized for its ease of shaping, re-usability, physical properties and its low cost. One of plastics' greatest benefits is its ability to hold a given color from within allowing it to avoid use of paint. This paper will give a brief overview on the effects of pigments when incorporated in a polyolefin. It will provide a classification of the main types of pigments and how each effect the properties of the product through: crystallization, weatherability, opacity, coloristic values and of course viscosity.
Date:
December 2001
Creator:
Flora, Paul
System:
The UNT Digital Library
An Etiology of Juvenile Homicide in Dallas, Texas: 1988-1997
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Use of this item is restricted to the UNT Community
This research analyzed all juveniles involved in a homicide, both victims and offenders, in the city of Dallas, Texas from the years 1988 through 1997. This study addressed several research questions including the identification of risk factors common to both victims and offenders. Data for this study was obtained from the homicide files of the Dallas Police Department. The findings in part identify specific profiles of the victims and offenders, as well as identifying comparisons of risk factors between the two groups. Also identified are the relationships between the offenders and victims. Conclusions from this research present implications for law enforcement agencies, as well as furthering the etiology of juvenile homicide.
Date:
December 2001
Creator:
Haynes, Joseph
System:
The UNT Digital Library
Techniques Utilized in the Characterization of Existing Materials for Improved Material Development
It has become increasingly important to remain on the cutting edge of technology for a company to remain competitive and survive in today's high-tech industries. To do this, a company needs various resources dedicated to this cause. One of these resources is the use of existing materials, as starting points, for which improved materials can be based. For this, a company must rely on the characterization of existing materials to bring that base technology into their company. Through this evaluation, the base materials properties can be obtained and a material with improved properties can be developed. There are many techniques that can be used in characterizing an existing material, but not every technique is required to obtain the desired goal. The techniques utilized depend upon the depth of identification required. This report summarizes several techniques utilized in the characterization of existing materials and provides some examples of evaluated products.
Date:
December 2001
Creator:
Withaeger, Gary
System:
The UNT Digital Library
Two Fingers: Michael's Struggle
This written thesis gives an account of the creative production of Two Fingers: Michael's Struggle, a twenty-nine minute documentary video that explores the life of Michael Alan Rasch who suffers from Duchenne Muscular Dystrophy. It explains in detail the process of pre-production, production, and post-production of the documentary. It also discuses the integration of theories applied in the documentary. Two Fingers shows that although Michael has lived with the disease almost his entire life, his perspective and attitude are more about living and enjoying life. Through it, the filmmaker intends the viewer to gain a tremendously important lesson about the human spirit.
Date:
December 2001
Creator:
Youm, Mi-jung
System:
The UNT Digital Library
Development of a Pre-Impact Environmental Site Characterization for the Bryan Mound, Texas Strategic Petroleum Reserve
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This thesis presents a model for developing site-specific contingency plans to be used during spill response, remediation, and post-spill monitoring using the Strategic Petroleum Reserve's Bryan Mound site as a case study. Bird and vegetation observations provide baseline data for biological conditions, and sediment sampling for total petroleum hydrocarbons serves as a chemical component of the model. Results demonstrate previously unknown conditions that would hinder remediation and affect the persistence of petroleum contaminants. Results also established previously unmapped dominant bird and vegetation types likely to be impacted by a spill at the site. This model points to a reconsideration of individual facilities' responsibilities when planning for large-scale disasters and protecting the sensitive ecosystems surrounding their sites.
Date:
December 2001
Creator:
Hernandez, Sylvia A.
System:
The UNT Digital Library
Characterization of Moraxella bovis Aspartate Transcarbamoylase
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Aspartate transcarbamoylase (ATCase) catalyzes the first committed step in the pyrimidine biosynthetic pathway. Bacterial ATCases have been divided into three classes, class A, B, and C, based on their molecular weight, holoenzyme architecture, and enzyme kinetics. Moraxella bovis is a fastidious organism, the etiologic agent of infectious bovine keratoconjunctivitis (IBK). The M. bovis ATCase was purified and characterized for the first time. It is a class A enzyme with a molecular mass of 480 to 520 kDa. It has a pH optimum of 9.5 and is stable at high temperatures. The ATCase holoenzyme is inhibited by CTP > ATP > UTP. The Km for aspartate is 1.8 mM and the Vmax 1.04 µmol per min, where the Km for carbamoylphosphate is 1.05 mM and the Vmax 1.74 µmol per min.
Date:
December 2001
Creator:
Hooshdaran, Sahar
System:
The UNT Digital Library
The Changing Face of Ralph Lauren's Advertising: A New Lifestyle Image and Increased Nudity
Advertising, which is an important sales tool for brands to the masses, may produce lasting impressions of a company and its products. These impressions rely on a consistent message over time to maintain a brand's image. This study examines how Ralph Lauren's advertising images have changed from a country club lifestyle image to urban/hip. In addition, the study examines the increased use of nudity and sexual imagery in Lauren's advertising. The findings were obtained by content analyzing all Ralph Lauren advertisements appearing in Gentlemen's Quarterly magazine from 1980 to 2000 (N=283). The study finds that Ralph Lauren lifestyle images have become more urban/hip, and that Lauren's advertising is utilizing more nudity, sexual interaction, and homoerotic imagery. By examining Ralph Lauren's shifting brand image via its advertising, this study contributes to a greater understanding of the connection between advertising and a company's brand image.
Date:
August 2001
Creator:
LaCaze, Tray
System:
The UNT Digital Library
Dr. Richard Price, the Marquis de Condorcet, and the Political Culture of Friendship in the Late Enlightenment
The eighteenth century saw many innovations in political culture including the rise of the public sphere where political ideas were freely and openly discussed and criticized. The new public sphere arose within the institutions of private life such as the Republic of Letters and salons, so the modes of behavior in private life were important influences on the new political culture of the public sphere. By studying the lives and careers of Richard Price and the Marquis de Condorcet, I examine the role that the private institution of friendship played in the new political culture of the late Enlightenment. During the 1780s, friendship became an important political symbol that represented the enlightened ideals of equality, reciprocity, liberty, and humanitarianism.
Date:
August 2001
Creator:
Kruckeberg, Robert Dale
System:
The UNT Digital Library
Job Satisfaction of Juvenile Facility Directors: Results from a National Survey
This study utilizes a national survey to measure the job satisfaction of juvenile facility directors. The prior literature has focused on the experiences of line personnel within the adult correctional system, and this research serves to provide new information regarding this specific population. The current study will address the predictors and correlates of a director's job satisfaction. It is hypothesized that specific characteristics within the organization will predict job satisfaction. Issues regarding staff within an institution and their effect on a director's job satisfaction are the focus. Results indicate that staff issues significantly contribute to the job satisfaction of a director. Specifically, this research can be used to understand facility director retention, staff and juvenile related issues, and the effect of job satisfaction on criminal justice policy issues.
Date:
August 2001
Creator:
Flanigan, Amy Renee
System:
The UNT Digital Library