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Ion Uptake Determination of Dendrochronologically-Dated Trees Using Neutron Activation Analysis

Description: Uptake of metal ions by plan roots is a function of the type and concentration of metal in the soil, the nutrient biochemistry of the plant, and the immediate environment of the root. Uptake of gold (Au) is known to be sensitive to soil pH for many species. Soil acidification due to acid precipitation following volcanic eruptions can dramatically increase Au uptake by trees. Identification of high Au content in tree rings in dendrochronologically-dated, overlapping sequences of trees allows the… more
Date: March 30, 2009
Creator: Unlu, Kenan; Kuniholm, P. I.; Schwarz, D. K. H.; Cetiner, N. O. & Chiment, J. J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Development of an Engineered Producet Storage Concept for the UREX+1 Combined Transuraqnic?Lanthanide Product Streams

Description: The U.S. Department of Energy is developing next generation processing methods to recycle uranium and transuranic (TRU) isotopes from spent nuclear fuel. The objective of the 3-year project described in this report was to develop near-term options for storing TRU oxides isolated through the uranium extraction (UREX+) process. More specifically, a Zircaloy matrix cermet was developed as a storage form for transuranics with the understanding that the cermet also has the ability to serve as a iner… more
Date: March 1, 2009
Creator: McDeavitt, Dr. Sean M.; Downar, Thomas J.; Taiwo, Dr. Temitope A. & Williamson, Dr. Mark A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Transfer of Mand-to-Tact and Tact-to-Mand Topographies in Two Vocal-Verbal Children with Autism: A Replication and Extension Study

Description: Skinner (1957) suggested that different verbal operants are acquired independently of each other and establishing a verbal operant as a mand will not necessarily result in the appearance of a tact having the same response form and vice versa. Recent empirical research has found that newly acquired mands and tacts can be transferred to different relations without direct training. The present study investigated 1) how verbal responses taught as pure mands affect untrained tact relations; 2) how… more
Date: May 2009
Creator: Ruiz, Julio
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Development of a Progeny Marker for Steelhead; A Thesis submitted to Oregon State University.

Description: This study was undertaken to determine if strontium chloride could be used to create a trans-generational otolith mark in steelhead (Oncorhynchus mykiss). I completed two strontium injection trials and a survey of juvenile steelhead from various steelhead hatcheries. The two trials measured Sr:Ca ratios in otoliths in response to injections and the survey measured the natural variation in Sr:Ca ratios in otoliths of juvenile hatchery steelhead in response to the natural variation. In 2003, adul… more
Date: April 15, 2009
Creator: Shippentower, Gene E.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

A Comparative Study of Advanced Placement and Learning Differenced Students: Comparing Internal Attribution and Correlation to Hopefulness.

Description: The goal of this research was to determine if there are significant differences in the attribution styles for positive and negative events between students of differing ability and the correlation of these attribution styles to hopefulness. The study examined twelfth grade advanced placement (AP N = 45) students and twelfth grade students with documented learning differences enrolled in college preparatory classes (CP-LD N = 14). Both groups of students came from high socioeconomic backgrounds.… more
Date: May 2009
Creator: Hayden, Johanna
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

An Attempt to Dissociate Effects of Response Requirements and Sample Duration in Conditional Discrimination Learning with Pigeons.

Description: Attempts to control various aspects of response requirements and sample viewing durations of sample stimuli show that an increase in both facilitates acquisition of conditional discriminations. Despite these attempts, few empirical data exist that demonstrate the relative contributions of both response- and time-dependent schedules. In addition, viewing opportunities of sample stimuli are present outside of the researchers' control, allowing for 'unauthorized sample viewing.' This study employe… more
Date: May 2009
Creator: Levine, Joshua
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Effects of Picture Exchange Training on Communication Topographies

Description: The Picture Exchange Communication System (PECS) has been used with children with autism and other developmental disabilities as an alternative to vocal communication. Some researchers have reported rapid acquisition of picture-exchange requesting as well as increased vocal speech and increased spontaneous social interactions following PECS training. Earlier research has found that although 3 children with autism learned to exchange pictures for preferred items during PECS training, requestin… more
Date: May 2009
Creator: Haray, Aimee H.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

The Effect of Social Support on Risky Sexual Behavior in Homeless Adolescent Youth.

Description: This study examines the relationship between social support and youth's high-risk behaviors. The data were obtained from the Midwest Homeless and Runaway Adolescent Project (MHRAP) in 1996. In the Midwestern United States, this study examines the hypothesis that youth with high social support will have low sexual risk behaviors. The study found that youths who had someone to turn to, a greater number of close friends, and someone they could count on were less likely to engage in risky sexual be… more
Date: December 2009
Creator: Ford, Alison Nicole
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

The Effects of PECS Training on Symbolic Matching Skills in Learners with Autism

Description: This study evaluated whether picture exchange communication system (PECS) training would result in the development of conditional relations among corresponding pictures, objects (reinforcers) and spoken words used in PECS training with learners with developmental disabilities. Three participants with autism and mental retardation were trained to use PECS. Match-to-sample procedures were used to assess all possible conditional relations among stimuli before, during, and after PECS training. … more
Date: May 2009
Creator: Cranmer, Elizabeth
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Comparison of Source Diversity and Channel Diversity Methods on Symmetric and Fading Channels.

Description: Channel diversity techniques are effective ways to combat channel fading and noise in communication systems. In this thesis, I compare the performance of source and channel diversity techniques on fading and symmetric continuous channels. My experiments suggest that when SNR is low, channel diversity performs better, and when SNR is high, source diversity shows better performance than channel diversity.
Date: August 2009
Creator: Li, Li
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Does Stimulus Complexity Affect Acquisition of Conditional Discriminations and the Emergence of Derived Relations?

Description: Despite the central importance of conditional discriminations to the derivation of equivalence relations, there is little research relating the dynamics of conditional discrimination learning to the derivation of equivalence relations. Prior research has shown that conditional discriminations with simple sample and comparison stimuli are acquired faster than conditional discriminations with complex sample and comparison stimuli. This study attempted to replicate these earlier results and extend… more
Date: December 2009
Creator: Martin, Tiffani L.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

A head start on reading for children in a Head Start preschool program.

Description: Literacy is a fundamental to all areas of learning. Early reading experiences prior to elementary school and kindergarten years are critical factors for later reading success. This study evaluated the effect Direct Instruction® reading procedures vs. Scholastic Early Childhood Program® reading procedures on the production of letter names, letter sounds, CV and CVC blends by preschool-aged students in a Head Start program. Results showed the intervention group improved in all areas, while the co… more
Date: May 2009
Creator: Osley, Kristin R.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Final Report: Interphase Analysis and Control in Fiber Reinforced Thermoplastic Composites

Description: This research program builds upon a multi-disciplinary effort in interphase analysis and control in thermoplastic matrix polymer matrix composites (PMC). The research investigates model systems deemed of interest by members of the Automotive Composites Consortium (ACC) as well as samples at the forefront of PMC process development (DRIFT and P4 technologies). Finally, the research investigates, based upon the fundamental understanding of the interphases created during the fabrication of thermop… more
Date: March 14, 2009
Creator: Kellar, Jon J.; Cross, William M. & Kjerengtroen, Lidvin
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Comparison of Homework Systems (Four Web-Based) used in First-Semester General Chemistry

Description: Web-based homework systems are becoming more common in general chemistry as instructors face ever-increasing enrollment. Yet providing meaningful feedback on assignments remains of the utmost importance. Chemistry instructors consider completion of homework integral to students' success in chemistry, yet only a few studies have compared the use of Web-based systems to the traditional paper-and-pencil homework within general chemistry. This study compares the traditional homework system to four … more
Date: May 2009
Creator: Belland, Joshua
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

An investigation into graph isomorphism based zero-knowledge proofs.

Description: Zero-knowledge proofs protocols are effective interactive methods to prove a node's identity without disclosing any additional information other than the veracity of the proof. They are implementable in several ways. In this thesis, I investigate the graph isomorphism based zero-knowledge proofs protocol. My experiments and analyses suggest that graph isomorphism can easily be solved for many types of graphs and hence is not an ideal solution for implementing ZKP.
Date: December 2009
Creator: Ayeh, Eric
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Maternal employment: Factors related to role strain.

Description: Past literature suggests that working mothers are at an increased risk for experiencing role strain compared to other employed adults. The current study investigated attitudes and beliefs of 783 working mothers of 15-month-old children using data from the National Institute of Child Health and Human Development's Study of Early Child Care and Youth Development. Working mothers' levels of role strain was associated with perceived social support, attitudes toward maternal employment, job and pare… more
Date: August 2009
Creator: LoCascio, Stephanie
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Immediate and Subsequent Effects of Fixed-Time Delivery of Therapist Attention on Problem Behavior Maintained by Attention

Description: The purpose of the current study was to investigate the immediate and subsequent effects of fixed-time attention on problem behavior maintained by therapist attention utilizing a three-component multiple-schedule design. The treatment analysis indicated that fixed-time attention produced a significant immediate decrease in the frequency of physically disruptive behavior (PDB), represented by low frequencies of PDB in Component 2, as well as a continued subsequent effect, represented by lower fr… more
Date: August 2009
Creator: Walker, Stephen Frank
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

High Resolution Satellite Images and LiDAR Data for Small-Area Building Extraction and Population Estimation

Description: Population estimation in inter-censual years has many important applications. In this research, high-resolution pan-sharpened IKONOS image, LiDAR data, and parcel data are used to estimate small-area population in the eastern part of the city of Denton, Texas. Residential buildings are extracted through object-based classification techniques supported by shape indices and spectral signatures. Three population indicators -building count, building volume and building area at block level are deriv… more
Date: December 2009
Creator: Ramesh, Sathya
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Synthesis and Characterization of Platinum(II)(2-(9-anthracenylylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione)(dichloride), Platinum(II)(2-(9-anthracenylylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione(maleonitriledithiolate), and Platinum(II)(4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione)(4-Methyl-1,2-benzene dithiol)

Description: Substitution of the 1,5-cyclooctadiene (cod) ligand in PtCl2(cod) (1) by the diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) yields PtCl2(bpcd) (2). Knoevenagel condensation of 2 with 9-anthracenecarboxaldehyde leads to the functionalization of the bpcd ligand and formation of the corresponding 2-(9-anthracenylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (abpcd) substituted compound PtCl2(abpcd) (3), which is also obtained from the direct reaction of 1… more
Date: December 2009
Creator: Hunt, Sean W.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

The Big Five Personality Characteristics of World of Warcraft Players

Description: This study is a comparative analysis of the personality characteristics of a sample of World of Warcraft players (n = 147) and a large normative sample (n = 20,993). The 120-item International Personality Item Pool, based on the five factor model, is used. Independent t-tests were conducted and statistical significance was found for some factors; however, the effect sizes were small, indicating a limited practical difference between the two groups.
Date: May 2009
Creator: Winter, Jessica L.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Using a Behavioral Treatment Package to Teach Tolerance to Skin Care Products to a Child with Autism: A Systematic Replication

Description: The purpose of this study is to investigate the effectiveness of a treatment package to teach a child with autism to willingly accept skin care products conducive to health and normal everyday living. The current study uses graduated exposure, modeling and contingent social attention to teach the child to accept the application of skin care products previously avoided. Results of the study showed that the participant tolerated criterion amounts of all target stimuli with both experimenter and … more
Date: May 2009
Creator: Vidosevic, Tania A.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Development, Implementation, and Analysis of a Contact Model for an Infectious Disease

Description: With a growing concern of an infectious diseases spreading in a population, epidemiology is becoming more important for the future of public health. In the past epidemiologist used existing data of an outbreak to help them determine how an infectious disease might spread in the future. Now with computational models, they able to analysis data produced by these models to help with prevention and intervention plans. This paper looks at the design, implementation, and analysis of a computational m… more
Date: May 2009
Creator: Thompson, Brett Morinaga
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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