Matching Items (43,917)
Description
In a large network (graph) it would be desirable to guarantee the existence of some local property based only on global knowledge of the network. Consider the following classical example: how many connections are necessary to guarantee that the network contains three nodes which are pairwise adjacent? It turns out that more than n^2/4 connections are needed, and no smaller number will suffice in general. Problems of this type fall into the category of ``extremal graph theory.'' Generally speaking, extremal graph theory is the study of how global parameters of a graph are related to local properties. This dissertation deals with the relationship between minimum degree conditions of a host graph G and the property that G contains a specified spanning subgraph (or class of subgraphs). The goal is to find the optimal minimum degree which guarantees the existence of a desired spanning subgraph. This goal is achieved in four different settings, with the main tools being Szemeredi's Regularity Lemma; the Blow-up Lemma of Komlos, Sarkozy, and Szemeredi; and some basic probabilistic techniques.
Contributors
DeBiasio, Louis (Author) / Kierstead, Henry A (Thesis advisor) / Czygrinow, Andrzej (Thesis advisor) / Hurlbert, Glenn (Committee member) / Kadell, Kevin (Committee member) / Fishel, Susanna (Committee member) / Arizona State University (Publisher)
Created
2011
Description
The intent of this research is to determine if cool roofs lead to increased energy use in the U.S. and if so, in what climates. Directed by the LEED environmental building rating system, cool roofs are increasingly specified in an attempt to mitigate urban heat island effect. A typical single story retail building was simulated using eQUEST energy software across seven different climatic zones in the U.S.. Two roof types are varied, one with a low solar reflectance index of 30 (typical bituminous roof), and a roof with SRI of 90 (high performing membrane roof). The model also varied the perimeter / core fraction, internal loads, and schedule of operations. The data suggests a certain point at which a high SRI roofing finish results in energy penalties over the course of the year in climate zones which are heating driven. Climate zones 5 and above appear to be the flipping point, beyond which the application of a high SRI roof creates sufficient heating penalties to outweigh the cooling energy benefits.
Contributors
Lee, John (Author) / Bryan, Harvey (Thesis advisor) / Marlin, Marlin (Committee member) / Ramalingam, Muthukumar (Committee member) / Arizona State University (Publisher)
Created
2011
Description
The Kasturba Gandhi Balika Vidyalaya (KGBV) policy scheme launched in 2004 by the Ministry of Human Resource Development, the Government of India, aims to provide secondary level education (grade 6-8) for girls residing predominantly in minority communities, the Scheduled Caste (SC), the Scheduled Tribe (ST), and the Other Backward Caste (OBC). Since its launch, the Government of India established 2,578 KGBV schools in 27 states and union territories (UTs). The present study examines the new policy and its implementation at three KGBV schools located in rural villages of Uttar Pradesh (UP), India. The purpose was to analyze the Government of India's approach to increasing education opportunity and participation for educationally disadvantaged girls using the empowerment framework developed by Deepa Narayan. Observations at three schools, interviews with teachers and staff members of the implementation agency (i.e., Mahila Samakhya (MS)), and surveys administered to 139 teachers were conducted over a four month period in 2009. Adopting creative teaching approaches and learning activities, MS creates safe learning community which is appropriate for the rural girls. MS gives special attention to nurturing the girls' potential and empowering them inside and outside the school environment through social discussion, parental involvement, rigid discipline and structure, health and hygiene education, and physical and mental training. Interviews with the state program director and coordinators identified some conflicts within government policy schemes such as the Teacher-pupil ratios guidelines as a part of the programs for the universalization of elementary education. Major challenges include a high turnover rate of teachers, a lack of female teachers, a lack of provision after Class 8, and inadequate budget for medical treatment. Recommendations include promoting active involvement of male members in the process of girls' empowerment, making MS approaches of girls' education in rural settings standardized for wider dissemination, and developing flexible and strong partnership among local agencies and government organizations for effective service delivery.
Contributors
Watanabe, Miku (Author) / Fischman, Gustavo (Thesis advisor) / Wiley, Terrence (Committee member) / Mccarty, Teresa (Committee member) / Arizona State University (Publisher)
Created
2011
Description
The under-representation of women in science, technology, engineering and mathematics (STEM) fields indicates the presence of gender related barriers that impacted the persistence of women in science and engineering doctoral studies. The purpose of this study was to investigate the barriers of women doctoral students in STEM fields which identified supporting factors for them as well. This study also tried to determine if there was any difference in perceiving barriers among three disciplines - engineering, life sciences and natural sciences. An online questionnaire (19 Likert-type questions and one open-ended question) was sent to women STEM doctoral students studying at the Arizona State University (ASU). Questions were based on some factors which might act as obstacles or supports during their doctoral studies. Both quantitative and qualitative analyses were conducted. Factors such as work-life balance, time-management, low self-confidence, lack of female role model, fewer numbers of women in science and engineering classes, and male dominated environment revealed as significant barriers according to both the analyses but factors such as difficulty with the curriculum, gender discrimination, and two-career problem were chosen as barriers only in the free response question. Positive treatment from advisor, family support, availability of funding, and absence of sexual harassment assisted these women continuing their PhD programs at ASU. However, no significant difference was observed with respect to perceiving barriers among the three groups mentioned above. Recommendations for change in science and engineering curricula and active recruitment of female faculty are discussed to reduce or at best to remove the barriers and how to facilitate participation and retention of more women in STEM fields especially at the doctoral level.
Contributors
Chaudhuri, Dola (Author) / Baker, Dale (Thesis advisor) / Sandlin, Jennifer (Committee member) / Edwards, Vicki (Committee member) / Arizona State University (Publisher)
Created
2011
Description
This study examined the influence of childhood aggression, peer exclusion and associating with deviant peers on the development of antisocial behavior in early adolescence. To gain a stronger understanding of how these factors are associated with antisocial behavior and delinquency, multiple alternative pathways were examined based on additive, mediation and incidental models. A parallel process growth model was specified to assess whether early childhood aggression and peer exclusion (in 1st grade) and intra-individual increases in aggressive behaviors and exclusion through childhood (grades 1 to 6) are predictive of associating with deviant peers (in 7th grade) and antisocial behavior (in 8th grade). Based on a sample of 383 children (193 girls and 190 boys), results showed the strongest support for an additive effects model in which early childhood aggression, increases in aggression, increases in peer exclusion and associating with more deviant peers all predicted antisocial behavior. These findings have implications for how children's psychological adjustment is impacted by their behavioral propensities and peer relational context and the importance of examining developmental processes within and between children over time.
Contributors
Ettekal, Idean (Author) / Ladd, Gary W (Thesis advisor) / Eggum, Natalie D (Committee member) / Thompson, Marilyn S (Committee member) / Arizona State University (Publisher)
Created
2011
Description
The increasing isolation and segregation of children in American cities and suburbs is of special significance. This has meant a loss of freedom for children to explore their neighborhood and city as they get older, their exclusion from varied contacts with diverse adults in a variety of settings, and their consequent inability to learn from personal experience and observation, so essential to social and emotional development. The purpose of this study is to measure the differences in child-friendliness between neighborhoods with different income levels by developing an indicator framework that can be used by planning departments and other local authorities based on available data. The research also focus on what other factor (besides income) influences child-friendliness in a city at the neighborhood level. If a relationship does exist, how big is the difference in terms of child-friendliness between low-income and high-income neighborhoods, and what indicators play the most important role in creating the difference? Neighborhoods in the city of Glendale, Arizona serve as case studies to aid in refining the assessment method, and show the potential for how cities can become more child-friendly. The neighborhoods were selected based on income, same size and different location.
Contributors
Rakhimova, Nelya (Author) / Stein, Jay (Thesis advisor) / Pijawka, David (Committee member) / Crewe, Katherine (Committee member) / Arizona State University (Publisher)
Created
2011
Description
The purpose of this study was to investigate the effect of partial exemplar experience on category formation and use. Participants had either complete or limited access to the three dimensions that defined categories by dimensions within different modalities. The concept of "crucial dimension" was introduced and the role it plays in category definition was explained. It was hypothesized that the effects of partial experience are not explained by a shifting of attention between dimensions (Taylor & Ross, 2009) but rather by an increased reliance on prototypical values used to fill in missing information during incomplete experiences. Results indicated that participants (1) do not fill in missing information with prototypical values, (2) integrate information less efficiently between different modalities than within a single modality, and (3) have difficulty learning only when partial experience prevents access to diagnostic information.
Contributors
Crawford, Thomas (Author) / Homa, Donald (Thesis advisor) / Mcbeath, Micheal (Committee member) / Glenberg, Arthur (Committee member) / Arizona State University (Publisher)
Created
2011
Description
A relatively simple subset of nanotechnology - nanofluids - can be obtained by adding nanoparticles to conventional base fluids. The promise of these fluids stems from the fact that relatively low particle loadings (typically <1% volume fractions) can significantly change the properties of the base fluid. This research explores how low volume fraction nanofluids, composed of common base-fluids, interact with light energy. Comparative experimentation and modeling reveals that absorbing light volumetrically (i.e. in the depth of the fluid) is fundamentally different from surface-based absorption. Depending on the particle material, size, shape, and volume fraction, a fluid can be changed from being mostly transparent to sunlight (in the case of water, alcohols, oils, and glycols) to being a very efficient volumetric absorber of sunlight. This research also visualizes, under high levels of irradiation, how nanofluids undergo interesting, localized phase change phenomena. For this, images were taken of bubble formation and boiling in aqueous nanofluids heated by a hot wire and by a laser. Infrared thermography was also used to quantify this phenomenon. Overall, though, this research reveals the possibility for novel solar collectors in which the working fluid directly absorbs light energy and undergoes phase change in a single step. Modeling results indicate that these improvements can increase a solar thermal receiver's efficiency by up to 10%.
Contributors
Taylor, Robert (Author) / Phelan, Patrick E (Thesis advisor) / Adrian, Ronald (Committee member) / Trimble, Steve (Committee member) / Posner, Jonathan (Committee member) / Maracas, George (Committee member) / Arizona State University (Publisher)
Created
2011
Description
This thesis describes a synthetic task environment, CyberCog, created for the purposes of 1) understanding and measuring individual and team situation awareness in the context of a cyber security defense task and 2) providing a context for evaluating algorithms, visualizations, and other interventions that are intended to improve cyber situation awareness. CyberCog provides an interactive environment for conducting human-in-loop experiments in which the participants of the experiment perform the tasks of a cyber security defense analyst in response to a cyber-attack scenario. CyberCog generates the necessary performance measures and interaction logs needed for measuring individual and team cyber situation awareness. Moreover, the CyberCog environment provides good experimental control for conducting effective situation awareness studies while retaining realism in the scenario and in the tasks performed.
Contributors
Rajivan, Prashanth (Author) / Femiani, John (Thesis advisor) / Cooke, Nancy J. (Thesis advisor) / Lindquist, Timothy (Committee member) / Gary, Kevin (Committee member) / Arizona State University (Publisher)
Created
2011
Description
Amorphous oxide semiconductors are promising new materials for various optoelectronic applications. In this study, improved electrical and optical properties upon thermal and microwave processing of mixed-oxide semiconductors are reported. First, arsenic-doped silicon was used as a model system to understand susceptor-assisted microwave annealing. Mixed oxide semiconductor films of indium zinc oxide (IZO) and indium gallium zinc oxide (IGZO) were deposited by room-temperature RF sputtering on flexible polymer substrates. Thermal annealing in different environments - air, vacuum and oxygen was done. Electrical and optical characterization was carried out before and after annealing. The degree of reversal in the degradation in electrical properties of the thin films upon annealing in oxygen was assessed by subjecting samples to subsequent vacuum anneals. To further increase the conductivity of the IGZO films, Ag layers of various thicknesses were embedded between two IGZO layers. Optical performance of the multilayer structures was improved by susceptor-assisted microwave annealing and furnace-annealing in oxygen environment without compromising on their electrical conductivity. The post-processing of the films in different environments was used to develop an understanding of mechanisms of carrier generation, transport and optical absorption. This study establishes IGZO as a viable transparent conductor, which can be deposited at room-temperature and processed by thermal and microwave annealing to improve electrical and optical performance for applications in flexible electronics and optoelectronics.
Contributors
Gadre, Mandar (Author) / Alford, Terry L. (Thesis advisor) / Schroder, Dieter (Committee member) / Krause, Stephen (Committee member) / Theodore, David (Committee member) / Arizona State University (Publisher)
Created
2011