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Study of temporal variation of radon concentrations in public drinking water supplies
The Environmental Protection Agency (EPA) has proposed a Maximum Contaminant Level (MCL) for radon-222 in public drinking water supplies of 300 pCi/L. Proposed monitoring requirements include collecting quarterly grab samples for the first year, then annual samples for the remainder of the compliance cycle provided first year quarterly samples average below the MCL. The focus of this research was to study the temporal variation of groundwater radon concentrations to investigate how reliably one can predict an annual average radon concentration based on the results of grab samples. Using a {open_quotes}slow-flow{close_quotes} collection method and liquid scintillation analysis, biweekly water samples were taken from ten public water supply wells in North Carolina (6 month - 11 month sampling periods). Based on study results, temporal variations exist in groundwater radon concentrations. Statistical analysis performed on the data indicates that grab samples taken from each of the ten wells during the study period would exhibit groundwater radon concentrations within 30% of their average radon concentration.
Date:
December 31, 1995
Creator:
York, E. L.
System:
The UNT Digital Library
An Analysis of Scientific Learning in Growing Silkworms
The purpose of this study is to give the results of a science experiment in an elementary grade in raising silkworms. The purpose of the experiment was not to learn the laws and principles of science, but to determine whether the life cycle of the silkworm would create a greater interest in the field of science.
Date:
1947
Creator:
Roberts, Odessa Hensley
System:
The UNT Digital Library
Potassium dihydrogen phosphate and potassium tantalate niobate pyroelectric materials and far-infrared detectors
This thesis discusses characterization of two ferroelectric materials and the fabrication of bolometers. Potassium tantalate niobate (KTN) and potassium dihydrogen phosphate (KDP) are chosen because they can be optimized for operation near 100K. Chap. 2 reviews the physics underlying pyroelectric materials and its subclass of ferroelectric materials. Aspects of pyroelectric detection are discussed in Chap. 3 including measurement circuit, noise sources, and effects of materials properties on pyroelectric response. Chap. 4 discusses materials selection and specific characteristics of KTN and KDP; Chap. 5 describes materials preparation; and Chap. 6 presents detector configuration and a thermal analysis of the pyroelectric detector. Electrical techniques used to characterize the materials and devices and results are discussed in Chap. 7 followed by conclusions on feasibility of KDP and KTN pyroelectric detectors in Chap. 8.
Date:
October 1, 1993
Creator:
Baumann, H. B.
System:
The UNT Digital Library
Ultra-short-period W/B{sub 4}C multilayers for x-ray optics-microstructure limits on reflectivity
Multilayer thin films are used as Bragg reflectors for soft x-rays in the energy range 50eV < E < 1000eV in many x-ray optics applications such as x-ray microscopes and telescopes, reducing optics for extreme ultraviolet (EUV) lithography, and x-ray polarizers and phase retarders. Applications often depend critically on reflectivity, which has not been systematically characterized for multilayer periods below 20{angstrom}. For this study, W/B{sub 4}C multilayers were fabricated by magnetron sputtering on Si(111), with periods from 48{angstrom} to as little as 4.7{angstrom}. The x-ray reflectivity measured at {lambda} = 1.54{angstrom} and at 45{degrees} incidence (289 eV < E < 860 eV) was found to decrease sharply for multilayer periods less than 15-20{angstrom}. Examination by high-resolution transmission electron microscopy (HRTEM) showed an expansion of the thickness of the W-rich layers of 30-40% from the nominal values, consistent with intermixture of the two materials during sputter growth, and discontinuous W-rich layers for multilayer periods below about 15{angstrom}. The experimental data for the specular reflectivity in the hard and soft x-ray regimes and the diffuse scattering fit well to a model of multilayer roughness. The model is expressed as a power-law dependence of roughness on spatial frequency. Analysis of small-angle scattering in …
Date:
December 1, 1997
Creator:
Walton, C. C.
System:
The UNT Digital Library
Development of a Procedure to Evaluate Groundwater Quality and Potential Sources of Contamination in the East Texas Basin
Access:
Use of this item is restricted to the UNT Community
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.
System:
The UNT Digital Library
The development of potassium tantalate niobate thin films for satellite-based pyroelectric detectors
Potassium tantalate niobate (KTN) pyroelectric detectors are expected to provide detectivities, of 3.7 x 10{sup 11} cmHz {sup {1/2}}W{sup {minus}1} for satellite-based infrared detection at 90 K. The background limited detectivity for a room-temperature thermal detector is 1.8 x 10{sup 10} cmHz{sup {1/2}}W{sup {minus}1}. KTN is a unique ferroelectric for this application because of the ability to tailor the temperature of its pyroelectric response by adjusting its ratio of tantalum to niobium. The ability to fabricate high quality KTN thin films on Si-based substrates is crucial to the development of KTN pyroelectric detectors. Si{sub x}N{sub y} membranes created on the Si substrate will provide the weak thermal link necessary to reach background limited detectivities. The device dimensions obtainable by thin film processing are expected to increase the ferroelectric response by 20 times over bulk fabricated KTN detectors. In addition, microfabrication techniques allow for easier array development. This is the first reported attempt at growth of KTN films on Si-based substrates. Pure phase perovskite films were grown by pulsed laser deposition on SrRuO{sub 3}/Pt/Ti/Si{sub x}N{sub y}/Si and SrRuO{sub 3}/Si{sub x}N{sub y}/Si structures; room temperature dielectric permittivities for the KTN films were 290 and 2.5, respectively. The dielectric permittivity for bulk grown, …
Date:
May 1997
Creator:
Cherry, H. B. B.
System:
The UNT Digital Library
Electrochemical arsenic remediation for rural Bangladesh
Arsenic in drinking water is a major public health problem threatening the lives of over 140 million people worldwide. In Bangladesh alone, up to 57 million people drink arsenic-laden water from shallow wells. ElectroChemical Arsenic Remediation(ECAR) overcomes many of the obstacles that plague current technologies and can be used affordably and on a small-scale, allowing for rapid dissemination into Bangladesh to address this arsenic crisis. In this work, ECAR was shown to effectively reduce 550 - 580 mu g=L arsenic (including both As[III]and As[V]in a 1:1 ratio) to below the WHO recommended maximum limit of 10 mu g=L in synthetic Bangladesh groundwater containing relevant concentrations of competitive ions such as phosphate, silicate, and bicarbonate. Arsenic removal capacity was found to be approximately constant within certain ranges of current density, but was found to change substantially between ranges. In order of decreasing arsenic removal capacity, the pattern was: 0.02 mA=cm2> 0.07 mA=cm2> 0.30 - 1.1 mA=cm2> 5.0 - 100 mA=cm2. Current processing time was found to effect arsenic removal capacity independent of either charge density or current density. Electrode polarization studies showed no passivation of the electrode in the tested range (up to current density 10 mA=cm2) and ruled out oxygen …
Date:
January 1, 2009
Creator:
Addy, Susan Amrose
System:
The UNT Digital Library
Employment Test Validation Based Upon Limited Criteria
This study is concerned with the experience of a particular company which undertook to improve its selection program through the installation of a test battery. This involved special adaptations of techniques commonly employed in industrial situations.
Date:
May 1960
Creator:
Stuckey, Billy J.
System:
The UNT Digital Library
The Democrat Years: A Growing Process
Changes of ownership, a seeming lack of interest in history, several deaths, and a fire prompted this study into the history of The Weatherford Democrat. Data for the thesis came from back issues of The Democrat, Ayer Directory of Newspapers and Periodicals, letters from former publishers, and personal observations and experiences of the writer, who worked on the paper 14 years. All but about a dozen years of the back issues are available. The thesis is written in chronological order, dating from the beginning in 1895 to 1967, when the Donrey Media Group gained control, ending local ownership. The Democrat is the survivor of more than 20 newspaper ventures in the city and is still the principal county paper.
Date:
August 1977
Creator:
Vandagriff, Jon R.
System:
The UNT Digital Library
Personal Study and Comparative Analysis of the Track Men and the Football Men at North Texas State Teachers College for the Period of Ten Years (1930-1940)
This study deals with an investigation of letterman in track in North Texas State Teachers College during the ten- year period of 1930-31 through 1939-40, as compared with football lettermen of the same period. More especially, it is a study of the program, the accomplishments, and the later occupations followed by the individual athletes who earned letters in track. The status of the athletes was considered from the standpoint of their athletic and scholastic attainments as well as their social activities while in college, The athletes were also considered from the standpoint of position and location since leaving college. It is recommended that in the near future a similar study be made of the other sports in North Texas State College to parallel this study.
Date:
August 1949
Creator:
Brown, Elmer Arthur
System:
The UNT Digital Library
The Development of the Textile Industry in Texas
"At the present time the textile industry in Texas is seeking to normalize itself after running at a peak production for the last ten years. It is one of the most competitive of our industries. The mills in Texas have always had to compete with the large mills located in the Eastern states, which have many advantages over the Texas mills. ... It has been only recently since the manufacture of synthetic fibers began in Texas, and it has not yet been fully completed. At the present time only the ingredients for synthetic fibers are produced in Texas. ... Cotton and wool manufacturing may develop gradually, but in the field of synthetics appears the greatest opportunity for a future textile industry in Texas."
Date:
June 1950
Creator:
Droze, Wilmon H.
System:
The UNT Digital Library
Cast-Iron Facades in Texas
In this limited survey, nineteenth-century cast-iron facades in Texas were recorded and compared to iron-fronted buildings in New York City. It was found that generally, the still existing buildings in Texas cities and towns were similar to those in New York in style but differed to the extent to which the cast-iron elements were used. It appears that nineteenth-century builders in Texas knew of New York trends in cast-iron but had definite regional preferences.
Date:
December 1978
Creator:
Giritz, Cheryl A.
System:
The UNT Digital Library
Asleep in the Arms of God
A work of creative fiction in the form of a short novel, Asleep in the Arms of God is a limited-omniscient and omniscient narrative describing the experiences of a man named Wafer Roberts, born in Jack County, Texas, in 1900. The novel spans the years from 1900 to 1925, and moves from the Keechi Valley of North Texas, to Fort Worth and then France during World War One, and back again to the Keechi Valley. The dissertation opens with a preface, which examines the form of the novel, and regional and other aspects of this particular work, especially as they relate to the postmodern concern with fragmentation and conditional identity. Wafer confronts in the novel aspects of his own questionable history, which echo the larger concern with exploitative practices including racism, patriarchy, overplanting and overgrazing, and pollution, which contribute to and climax in the postmodern fragmentation. The novel attempts to make a critique of the exploitative rage of Western civilization.
Date:
December 1999
Creator:
Clay, Kevin M.
System:
The UNT Digital Library
The Status of Transitional First Grade Programs in Regions 10 and 11 in North Central Texas
The purposes of this study were to identify public school districts that currently offer, or are planning to offer, transitional first-grade programs, to describe existing transitional programs, to describe the genesis of transitional first-grade classes in the North Texas area, and to assist in the establishment of a networking system for schools in the North Central Texas area that currently have, or are planning to have, transitional first-grade classes. The 158 school districts in Regions 10 and 11 were surveyed. The findings of the study indicate that about one-third of the districts offered transitional first-grade programs during the 1988-89 school year, and two-thirds of the districts saw a need for transitional first-grade classes. These transitional programs were implemented to meet the needs of children who had completed kindergarten but were not ready for regular first grade. Transitional first-grade programs focus primarily on language arts and math skills for kindergarten and early first grade. While curriculum materials vary from district to district, language arts is likely to be based on a whole-language approach, and math is likely to focus on manipulatives.. Kindergarten teacher observation is used in the screening procedures in the majority of the districts. A number of instruments are …
Date:
December 1989
Creator:
Angove, Dawn A. (Dawn Annyce)
System:
The UNT Digital Library
Development and Application of Novel Computer Vision and Machine Learning Techniques
The following thesis proposes solutions to problems in two main areas of focus, computer vision and machine learning. Chapter 2 utilizes traditional computer vision methods implemented in a novel manner to successfully identify overlays contained in broadcast footage. The remaining chapters explore machine learning algorithms and apply them in various manners to big data, multi-channel image data, and ECG data. L1 and L2 principal component analysis (PCA) algorithms are implemented and tested against each other in Python, providing a metric for future implementations. Selected algorithms from this set are then applied in conjunction with other methods to solve three distinct problems. The first problem is that of big data error detection, where PCA is effectively paired with statistical signal processing methods to create a weighted controlled algorithm. Problem 2 is an implementation of image fusion built to detect and remove noise from multispectral satellite imagery, that performs at a high level. The final problem examines ECG medical data classification. PCA is integrated into a neural network solution that achieves a small performance degradation while requiring less then 20% of the full data size.
Date:
August 2021
Creator:
Depoian, Arthur Charles, II
System:
The UNT Digital Library
The Texas Bandmasters Association: A Historical Study of Activities, Contributions, and Leadership (1920-1997)
The purpose of the study was to investigate the leadership role of the Texas Bandmasters Association (1920-1997) in the development of the band program in Texas. It sought to determine TBA's effect on the band movement in Texas, and ascertain how the TBA has contributed to the emphasis on performance focus that is associated with the Texas band tradition. In doing so, the study also provided information regarding the association's goals, purposes, activities, and contributions during the time period under investigation. The historical data for the study was compiled from documentary sources and personal interview. Documentary sources included minutes of meetings from 1920-1997, information contained in various periodicals including the Southwestern Musician combined with the Texas Music Educator, and a nearly complete set of clinic-convention programs. Historical data from past researchers, including several masters theses and doctoral dissertations, and tapes and transcripts of interviews conducted by past researchers, as well as interviews conducted by this researcher, were also utilized. Much of the historical data for the study was located at the Texas Music Educators Association archives, housed at the association headquarters in Austin, Texas. The researcher identified five periods of the association's history. In addition to developing a historical chronology, …
Date:
May 2000
Creator:
Shoop, Stephen Scott
System:
The UNT Digital Library
Occupational Influences on the Folklore of Graford, Texas
This study was basically concerned with the effect of occupation on the folklore of the people of Graford, Texas. The people interviewed in that area of North Central Texas were divided into three major occupational groups: ranchers, farmers, and farmer-laborers. At least two members from each of the occupational groups were interviewed; and these interviews revealed that their folklore included folktales, superstitions-remedies, songs, and customs, The customs included household, recreation, school, and church customs. Each informant's folklore was recorded directly as it was related. Then the information was placed in the appropriate categories of folklore. Finally, an analysis of the folklore from the standpoint of the informants occupation was completed. The findings indicated that the various occupations did influence each informant's folklore.
Date:
May 1975
Creator:
Conlee, Anita
System:
The UNT Digital Library
Career aspirations of high school home economics students in Palo Pinto County, Texas
181 adolescent home economics students in Palo Pinto County, Texas, were surveyed. The questions examined the following: grades and self concept of academic ability, self concept of academic ability and occupational aspirations, school size and occupational aspirations, sex and occupational aspirations, race and occupational aspirations, parents' occupational aspirations, parents' educational levels and occupational aspirations. The data suggested that career aspirations are positively related to self concept of ability, school grades, school size, race, parents' education, and fathers' occupations. Students' sex and their mothers' occupations were not shown to be related to career aspirations.
Date:
December 1978
Creator:
Singleton, Dawn A.
System:
The UNT Digital Library
The History of the Brazos Electric Power Co-operative
A history of the establishment of the Rural Electrification Administration and the Brazos Electric Power Cooperative.
Date:
January 1957
Creator:
Mitchell, Merlin Merton
System:
The UNT Digital Library
Red Dresses for Funerals
Red Dresses for Funerals contains a scholarly preface concerning the nature of factuality versus credibility in the writing of fiction. Four original short stories are included in this thesis. "A Night With Lawrence Welk" explores the relationship between a patient and student intern psychologist. "Red Dresses for Funerals" is about a wedding that plays a significant role in a variety of the characters' lives. "Trace Elements" is the only story involving young children. "Trace Elements" explores the beginning of understanding of some of the grimmer aspects of reality. "Expectations, Great and Otherwise" addresses the issue of denial. These stories are linked by their setting, a small town in Texas.
Date:
May 1994
Creator:
Brooks, Michelle Marie
System:
The UNT Digital Library
Evaluation of the School Plant of Union Grove High School in Upshur County, Texas, on the Basis of Health and Safety Environment for the School Population with Recommendations for Future Development
The purpose of this study was to make a critical evaluation of the school plant of Union Grove High School in Upshur County, Texas, in regards to health and safety environment.
Date:
1950
Creator:
Bartlett, J. Harold
System:
The UNT Digital Library
A Survey of the Public School System of Denton, Texas, with Reference to the Financial Status, the School Plants, the Instructional Staff, the Pupil Personnel, and the Libraries
The purpose of this study is to report a survey which the writer made of the public school system of Denton, Texas, dealing with the financial status, the school plants, the teaching personnel, the pupil personnel, and the libraries. The goal was to evaluate the schools in light of accepted standards for the factors considered, and to make certain recommendations regarding improvements.
Date:
1943
Creator:
Brooks, Marjorie Lynn Collier
System:
The UNT Digital Library
The Effects of Physical Exertion on Immediate Classroom Mental Performance of Second-Grade Elementary School Children
The aim of this investigation was to analyze the effects of induced physical exertion on the performance of an immediate mathematical mental ability task among second-grade students. The purpose of the study was to gain information concerning the effects of physical exertion on a mathematical mental task and to evaluate each of four experimental treatment periods (twenty, thirty, forty, and fifty minutes) used to induce physical exertion. Another purpose was to determine whether males or females were more affected by experimentally induced treatments of physical exertion. It was concluded that fifty minutes of prolonged physical exertion as induced by relay game activities had a positive effect on certain mathematical tasks. This conclusion was based on the comparison of the fifty minute treatment performance to the pre-test treatment performed without induced physical exertion. Another conclusion derived from the data was that physical exertion periods of twenty, thirty, and forty minutes had no significant positive or negative effect on certain mental performance when compared to a non-induced physical exertion treatment. It was also concluded that there were no significant differences between male and female mean difference performances.
Date:
December 1977
Creator:
Gabbard, Carl P.
System:
The UNT Digital Library
Party Platforms as Sources of Public Policy in Texas, 1946-1963
"This study is being made to assess the actual importance of the platform in recent gubernatorial elections in Texas. Because an intensive analysis is undertaken, the scope of this thesis has been limited in two ways. First, it is confined to the years 1946-1963 spanning the Administrations of Governors Beauford Jester, Allan Shivers, and Price Daniel. Secondly, in an attempt to compare the executives with one another, platform promises related to education, health and welfare, highways, and taxation adopted at the Democratic State Convention have been included. The method utilized to determine fulfillment of a political promise has been to compare the Governor's recommendations to the Legislature with the resulting action. In particular, an attempt has been made to (1) describe the Democratic primary election, with special reference to the issues raised; (2) to discuss the Democratic State Convention with a listing of the planks mentioned above; and (3) to analyze proposals in the Governor's State of the State Messages and special messages and to compare them with the resulting legislative action." -- leaf 1.
Date:
May 1969
Creator:
Schmidt, Johnell L.
System:
The UNT Digital Library