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 Collection: UNT Theses and Dissertations
Optical Properties of Christiansen Filter Systems

Optical Properties of Christiansen Filter Systems

Date: August 1960
Creator: Hinckley, Conrad C.
Description: This thesis examines the optical properties of Christiansen filter systems.
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Optical Transparent Pmma Composite Reinforced By Coaxial Electrospun Pan Hollow Nanofibers

Optical Transparent Pmma Composite Reinforced By Coaxial Electrospun Pan Hollow Nanofibers

Date: May 2013
Creator: Antoine, Donley
Description: Electrospinning has been recognized as an efficient technique for the fabrication of polymer fibers. These electrospun fibers have many applications across a broad range of industries. In this research, optical transparent composites were successfully fabricated by embedding polyacrylonitrile (PAN) hollow nanofibers into poly (methyl methacrylate) (PMMA) matrix. The hollow PAN nanofibers were prepared by coaxial electrospinning. The PAN was used as the shell solution, and the mineral oil was used as the core solution. The resulting fibers were then etched with octane to remove the mineral oil from the core. The hollow PAN fibers were then homogeneously distributed in PMMA resins to fabricate the composite. The morphology, transmittance and mechanical properties of the PAN/PMMA composite were then characterized with an ESEM, TEM, tensile testing machine, UV-vis spectrometer and KD2 Pro Decagon device. The results indicated that the hollow nanofibers have relatively uniform size with one-dimensional texture at the walls. The embedded PAN hollow nanofibers significantly enhanced the tensile stress and the Young's modulus of the composite (increased by 58.3% and 50.4%, respectively), while having little influence on the light transmittance of the composite. The KD2 Pro device indicated that the thermal conductivity of the PMMA was marginally greater than the ...
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Optimal Access Point Selection and Channel Assignment in IEEE 802.11 Networks

Optimal Access Point Selection and Channel Assignment in IEEE 802.11 Networks

Date: December 2004
Creator: Park, Sangtae
Description: Designing 802.11 wireless networks includes two major components: selection of access points (APs) in the demand areas and assignment of radio frequencies to each AP. Coverage and capacity are some key issues when placing APs in a demand area. APs need to cover all users. A user is considered covered if the power received from its corresponding AP is greater than a given threshold. Moreover, from a capacity standpoint, APs need to provide certain minimum bandwidth to users located in the coverage area. A major challenge in designing wireless networks is the frequency assignment problem. The 802.11 wireless LANs operate in the unlicensed ISM frequency, and all APs share the same frequency. As a result, as 802.11 APs become widely deployed, they start to interfere with each other and degrade network throughput. In consequence, efficient assignment of channels becomes necessary to avoid and minimize interference. In this work, an optimal AP selection was developed by balancing traffic load. An optimization problem was formulated that minimizes heavy congestion. As a result, APs in wireless LANs will have well distributed traffic loads, which maximize the throughput of the network. The channel assignment algorithm was designed by minimizing channel interference between APs. The ...
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Optimal design of Dutch auctions with discrete bid levels.

Optimal design of Dutch auctions with discrete bid levels.

Access: Use of this item is restricted to the UNT Community.
Date: May 2010
Creator: Li, Zhen
Description: The theory of auction has become an active research area spanning multiple disciplines such as economics, finance, marketing and management science. But a close examination of it reveals that most of the existing studies deal with ascending (i.e., English) auctions in which it is assumed that the bid increments are continuous. There is a clear lack of research on optimal descending (i.e., Dutch) auction design with discrete bid levels. This dissertation aims to fill this void by considering single-unit, open-bid, first price Dutch auctions in which the bid levels are restricted to a finite set of values, the number of bidders may be certain or uncertain, and a secret reserve price may be present or absent. These types of auctions are most attractive for selling products that are perishable (e.g., flowers) or whose value decreases with time (e.g., air flight seats and concert tickets) (Carare and Rothkopf, 2005). I began by conducting a comprehensive survey of the current literature to identify the key dimensions of an auction model. I then zeroed in on the particular combination of parameters that characterize the Dutch auctions of interest. As a significant departure from the traditional methods employed by applied economists and game theorists, ...
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Optimism, Delay Discounting, and Physical Exercise: The Role of Delay Discounting on Individual Levels of Exercise

Optimism, Delay Discounting, and Physical Exercise: The Role of Delay Discounting on Individual Levels of Exercise

Date: August 2010
Creator: Smith, Lauren Marie
Description: Deciding to exercise requires trade-offs between immediate and delayed benefits. These momentary decisions may be moderated by personality such that patterns of individual behavior emerge. The aim of the current study was to determine if higher levels of optimism and lower levels of delay discounting were related to exercise frequency. A sample of 360 undergraduate students completed a survey study related to understanding the choices made by undergraduates and how other factors relate to their decision-making. The survey included measures of optimism, delayed discounting, and self-reported exercise frequency in four domains: cardiovascular, resistance, sports, active lifestyle. Hierarchical linear regression was used to examine optimism and delay discounting as predictors of exercise frequency. Optimism and delay discounting were negatively correlated, but neither was related to exercise frequency. Furthermore, optimism and delay discounting were not significantly related to frequency spent in cardiovascular, resistance, or active lifestyle exercise. However, women scoring higher in delay discounting were more likely to participate in physical sports. The present study helps inform future research by showing potentially important psychosocial variables related to optimism, delay discounting, and exercise.
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Optimism, Health Locus of Control, and Quality of Life  of Women with Initial versus Recurrent Breast Cancer

Optimism, Health Locus of Control, and Quality of Life of Women with Initial versus Recurrent Breast Cancer

Date: May 2001
Creator: Graci, Gina
Description: Health Locus of Control (HLOC) and other predictors of Quality of Life (QL) were examined for women with an initial versus recurrent breast cancer diagnosis. Twenty-eight women with an initial breast cancer (IBC) diagnoses and twenty-eight women with recurrent breast cancer (RBC) diagnoses were recruited from doctors' offices and cancer support groups. Correlational analyses were used to assess the relationships between variables. No significant differences were found between women with IBC and RBC on Psychological QL. Doctor HLOC and Psychological QL were related for women with RBC (r = .481, p = .01) and marginally so for women with IBC (r = .329, p = .09). A positive correlation was also found between Doctor HLOC and Functional QL for both women with IBC (r = .464, p = .01) and women with RBC (r = .390, p = .04). After controlling for stage of cancer, women with RBC reported higher Functional QL than did women with IBC. Advanced (stages III or IV) versus early (stages I or II) cancer stage related to lower Functional QL, controlling for initial versus recurrent diagnosis (r = -.283, p = .01). A marginally significant relationship was also found for cancer stage, regardless of initial ...
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Optimization of Cell Culture Procedures for Growing Neural Networks on Microelectrode Arrays

Optimization of Cell Culture Procedures for Growing Neural Networks on Microelectrode Arrays

Date: December 2007
Creator: Santa Maria, Cara L.
Description: This thesis describes the development of an optimized method for culturing dissociated, monolayer neuronal networks from murine frontal cortex and midbrain. It is presented as a guidebook for use by cell culture specialists and laboratory personnel who require updated and complete procedures for use with microelectrode array (MEA) recording technology. Specific cell culture protocols, contamination prevention and control, as well common problems encountered within the cell culture facility, are discussed. This volume offers value and utility to the rapidly expanding fields of MEA recording and neuronal cell culture. Due to increasing interest in determining the mechanisms underlying Parkinson's disease, the newly developed procedures for mesencephalon isolation and culture on MEAs are an important research contribution.
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Optimization Theory in Administrative Analysis

Optimization Theory in Administrative Analysis

Date: August 1970
Creator: Brown, Kenneth Sherron
Description: The thesis of this study is that modern optimization theory is a natural extension of classical optimization theory. As such, modern optimization theory will be applied to administrative problems only after interpretive studies are made that provide (1) an explanation of the general theoretical development of the techniques of modern optimization theory, (2) computational algorithms for implementing the techniques of modern optimization theory, (3) detailed demonstrations of the computational aspects of each technique and its corresponding algorithm, and (4) an identification of the types of problems to which these techniques are applicable.
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Optimizing Non-pharmaceutical Interventions Using Multi-coaffiliation Networks

Optimizing Non-pharmaceutical Interventions Using Multi-coaffiliation Networks

Date: May 2013
Creator: Loza, Olivia G.
Description: Computational modeling is of fundamental significance in mapping possible disease spread, and designing strategies for its mitigation. Conventional contact networks implement the simulation of interactions as random occurrences, presenting public health bodies with a difficult trade off between a realistic model granularity and robust design of intervention strategies. Recently, researchers have been investigating the use of agent-based models (ABMs) to embrace the complexity of real world interactions. At the same time, theoretical approaches provide epidemiologists with general optimization models in which demographics are intrinsically simplified. The emerging study of affiliation networks and co-affiliation networks provide an alternative to such trade off. Co-affiliation networks maintain the realism innate to ABMs while reducing the complexity of contact networks into distinctively smaller k-partite graphs, were each partition represent a dimension of the social model. This dissertation studies the optimization of intervention strategies for infectious diseases, mainly distributed in school systems. First, concepts of synthetic populations and affiliation networks are extended to propose a modified algorithm for the synthetic reconstruction of populations. Second, the definition of multi-coaffiliation networks is presented as the main social model in which risk is quantified and evaluated, thereby obtaining vulnerability indications for each school in the system. Finally, maximization ...
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Optimizing Scientific and Social Attributes of Pharmaceutical Take Back Programs to Improve Public and Environmental Health

Optimizing Scientific and Social Attributes of Pharmaceutical Take Back Programs to Improve Public and Environmental Health

Date: August 2012
Creator: Stoddard, Kati Ireland
Description: Research continues to show that pharmaceutical environmental contamination has caused adverse environmental effects, with one of the most studied effects being feminization of fish exposed to pharmaceutical endocrine disruptors. Additionally, there are also public health risks associated with pharmaceuticals because in-home reserves of medications provide opportunities for accidental poisoning and intentional medication abuse. Pharmaceutical take back programs have been seen as a remedy to these concerns; however a thorough review of peer-reviewed literature and publicly available information on these programs indicates limited research has been conducted to validate these programs as a purported solution. Furthermore, there are significant data gaps on key factors relating to take back program participants. The purpose of this dissertation was therefore to address these gaps in knowledge and ultimately determine if take back programs could actually improve public and environmental health. This was accomplished by conducting social and scientific research on a take back program called Denton Drug Disposal Day (D4). Socioeconomic, demographic, and geographic characteristics of D4 participants were investigated using surveys and geographic analysis. Impacts on public health were determined by comparing medications collected at D4 events with medications reported to the North Texas Poison Center as causing adverse drug exposures in Denton ...
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