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- Genre: Doctoral Dissertation
- Status: Published
Description
This qualitative, action research study examines how teacher-writers' identities are constructed through the practice of revision in an extra-curriculum writing group. The writing group was designed to support the teacher-writers as they revised classroom research projects for submission for a scholarly journal. Using discourse analysis, the researcher explores how the teacher-writers' identities are constructed in the contested spaces of revision. This exploration focuses on contested issues that invariably emerge in a dynamic binary of reader/writer, issues of authority, ownership, and unstable reader and writer identities. By negotiating these contested spaces--these contact zones--the teacher-writers construct opportunities to flex their rhetorical agency. Through rhetorical agency, the teacher-writers shift their discoursal identities by discarding and acquiring a variety of discourses. As a result, the practice of revision constructs the teacher-writers identities as hybrid, as consisting of self and other.
ContributorsClark-Oates, Angela (Author) / Smith, Karen (Thesis advisor) / Roen, Duane (Thesis advisor) / Fischman, Gustavo (Committee member) / Early, Jessica (Committee member) / Arizona State University (Publisher)
Created2013
Description
Reductive dechlorination by members of the bacterial genus Dehalococcoides is a common and cost-effective avenue for in situ bioremediation of sites contaminated with the chlorinated solvents, trichloroethene (TCE) and perchloroethene (PCE). The overarching goal of my research was to address some of the challenges associated with bioremediation timeframes by improving the rates of reductive dechlorination and the growth of Dehalococcoides in mixed communities. Biostimulation of contaminated sites or microcosms with electron donor fails to consistently promote dechlorination of PCE/TCE beyond cis-dichloroethene (cis-DCE), even when the presence of Dehalococcoides is confirmed. Supported by data from microcosm experiments, I showed that the stalling at cis-DCE is due a H2 competition in which components of the soil or sediment serve as electron acceptors for competing microorganisms. However, once competition was minimized by providing selective enrichment techniques, I illustrated how to obtain both fast rates and high-density Dehalococcoides using three distinct enrichment cultures. Having achieved a heightened awareness of the fierce competition for electron donor, I then identified bicarbonate (HCO3-) as a potential H2 sink for reductive dechlorination. HCO3- is the natural buffer in groundwater but also the electron acceptor for hydrogenotrophic methanogens and homoacetogens, two microbial groups commonly encountered with Dehalococcoides. By testing a range of concentrations in batch experiments, I showed that methanogens are favored at low HCO3 and homoacetogens at high HCO3-. The high HCO3- concentrations increased the H2 demand which negatively affected the rates and extent of dechlorination. By applying the gained knowledge on microbial community management, I ran the first successful continuous stirred-tank reactor (CSTR) at a 3-d hydraulic retention time for cultivation of dechlorinating cultures. I demonstrated that using carefully selected conditions in a CSTR, cultivation of Dehalococcoides at short retention times is feasible, resulting in robust cultures capable of fast dechlorination. Lastly, I provide a systematic insight into the effect of high ammonia on communities involved in dechlorination of chloroethenes. This work documents the potential use of landfill leachate as a substrate for dechlorination and an increased tolerance of Dehalococcoides to high ammonia concentrations (2 g L-1 NH4+-N) without loss of the ability to dechlorinate TCE to ethene.
ContributorsDelgado, Anca Georgiana (Author) / Krajmalnik-Brown, Rosa (Thesis advisor) / Cadillo-Quiroz, Hinsby (Committee member) / Halden, Rolf U. (Committee member) / Rittmann, Bruce E. (Committee member) / Stout, Valerie (Committee member) / Arizona State University (Publisher)
Created2013
Description
Human breath is a concoction of thousands of compounds having in it a breath-print of physiological processes in the body. Though breath provides a non-invasive and easy to handle biological fluid, its analysis for clinical diagnosis is not very common. Partly the reason for this absence is unavailability of cost effective and convenient tools for such analysis. Scientific literature is full of novel sensor ideas but it is challenging to develop a working device, which are few. These challenges include trace level detection, presence of hundreds of interfering compounds, excessive humidity, different sampling regulations and personal variability. To meet these challenges as well as deliver a low cost solution, optical sensors based on specific colorimetric chemical reactions on mesoporous membranes have been developed. Sensor hardware utilizing cost effective and ubiquitously available light source (LED) and detector (webcam/photo diodes) has been developed and optimized for sensitive detection. Sample conditioning mouthpiece suitable for portable sensors is developed and integrated. The sensors are capable of communication with mobile phones realizing the idea of m-health for easy personal health monitoring in free living conditions. Nitric oxide and Acetone are chosen as analytes of interest. Nitric oxide levels in the breath correlate with lung inflammation which makes it useful for asthma management. Acetone levels increase during ketosis resulting from fat metabolism in the body. Monitoring breath acetone thus provides useful information to people with type1 diabetes, epileptic children on ketogenic diets and people following fitness plans for weight loss.
ContributorsPrabhakar, Amlendu (Author) / Tao, Nongjian (Thesis advisor) / Forzani, Erica (Committee member) / Lindsay, Stuart (Committee member) / Arizona State University (Publisher)
Created2013
Description
Transmission expansion planning (TEP) is a complex decision making process that requires comprehensive analysis to determine the time, location, and number of electric power transmission facilities that are needed in the future power grid. This dissertation investigates the topic of solving TEP problems for large power systems. The dissertation can be divided into two parts. The first part of this dissertation focuses on developing a more accurate network model for TEP study. First, a mixed-integer linear programming (MILP) based TEP model is proposed for solving multi-stage TEP problems. Compared with previous work, the proposed approach reduces the number of variables and constraints needed and improves the computational efficiency significantly. Second, the AC power flow model is applied to TEP models. Relaxations and reformulations are proposed to make the AC model based TEP problem solvable. Third, a convexified AC network model is proposed for TEP studies with reactive power and off-nominal bus voltage magnitudes included in the model. A MILP-based loss model and its relaxations are also investigated. The second part of this dissertation investigates the uncertainty modeling issues in the TEP problem. A two-stage stochastic TEP model is proposed and decomposition algorithms based on the L-shaped method and progressive hedging (PH) are developed to solve the stochastic model. Results indicate that the stochastic TEP model can give a more accurate estimation of the annual operating cost as compared to the deterministic TEP model which focuses only on the peak load.
ContributorsZhang, Hui (Author) / Vittal, Vijay (Thesis advisor) / Heydt, Gerald T (Thesis advisor) / Mittelmann, Hans D (Committee member) / Hedman, Kory W (Committee member) / Arizona State University (Publisher)
Created2013
Description
Surface plasmon resonance (SPR) has emerged as a popular technique for elucidating subtle signals from biological events in a label-free, high throughput environment. The efficacy of conventional SPR sensors, whose signals are mass-sensitive, diminishes rapidly with the size of the observed target molecules. The following work advances the current SPR sensor paradigm for the purpose of small molecule detection. The detection limits of two orthogonal components of SPR measurement are targeted: speed and sensitivity. In the context of this report, speed refers to the dynamic range of measured kinetic rate constants, while sensitivity refers to the target molecule mass limitation of conventional SPR measurement. A simple device for high-speed microfluidic delivery of liquid samples to a sensor surface is presented to address the temporal limitations of conventional SPR measurement. The time scale of buffer/sample switching is on the order of milliseconds, thereby minimizing the opportunity for sample plug dispersion. The high rates of mass transport to and from the central microfluidic sensing region allow for SPR-based kinetic analysis of binding events with dissociation rate constants (kd) up to 130 s-1. The required sample volume is only 1 μL, allowing for minimal sample consumption during high-speed kinetic binding measurement. Charge-based detection of small molecules is demonstrated by plasmonic-based electrochemical impedance microscopy (P-EIM). The dependence of surface plasmon resonance (SPR) on surface charge density is used to detect small molecules (60-120 Da) printed on a dextran-modified sensor surface. The SPR response to an applied ac potential is a function of the surface charge density. This optical signal is comprised of a dc and an ac component, and is measured with high spatial resolution. The amplitude and phase of local surface impedance is provided by the ac component. The phase signal of the small molecules is a function of their charge status, which is manipulated by the pH of a solution. This technique is used to detect and distinguish small molecules based on their charge status, thereby circumventing the mass limitation (~100 Da) of conventional SPR measurement.
ContributorsMacGriff, Christopher Assiff (Author) / Tao, Nongjian (Thesis advisor) / Wang, Shaopeng (Committee member) / LaBaer, Joshua (Committee member) / Chae, Junseok (Committee member) / Arizona State University (Publisher)
Created2013
Description
Autonomous vehicle control systems utilize real-time kinematic Global Navigation Satellite Systems (GNSS) receivers to provide a position within two-centimeter of truth. GNSS receivers utilize the satellite signal time of arrival estimates to solve for position; and multipath corrupts the time of arrival estimates with a time-varying bias. Time of arrival estimates are based upon accurate direct sequence spread spectrum (DSSS) code and carrier phase tracking. Current multipath mitigating GNSS solutions include fixed radiation pattern antennas and windowed delay-lock loop code phase discriminators. A new multipath mitigating code tracking algorithm is introduced that utilizes a non-symmetric correlation kernel to reject multipath. Independent parameters provide a means to trade-off code tracking discriminant gain against multipath mitigation performance. The algorithm performance is characterized in terms of multipath phase error bias, phase error estimation variance, tracking range, tracking ambiguity and implementation complexity. The algorithm is suitable for modernized GNSS signals including Binary Phase Shift Keyed (BPSK) and a variety of Binary Offset Keyed (BOC) signals. The algorithm compensates for unbalanced code sequences to ensure a code tracking bias does not result from the use of asymmetric correlation kernels. The algorithm does not require explicit knowledge of the propagation channel model. Design recommendations for selecting the algorithm parameters to mitigate precorrelation filter distortion are also provided.
ContributorsMiller, Steven (Author) / Spanias, Andreas (Thesis advisor) / Tepedelenlioğlu, Cihan (Committee member) / Tsakalis, Konstantinos (Committee member) / Zhang, Junshan (Committee member) / Arizona State University (Publisher)
Created2013
Description
In this mixed-methods study, I examined the relationship between professional development based on the Common Core State Standards for Mathematics and teacher knowledge, classroom practice, and student learning. Participants were randomly assigned to experimental and control groups. The 50-hour professional development treatment was administered to the treatment group during one semester, and then a follow-up replication treatment was administered to the control group during the subsequent semester. Results revealed significant differences in teacher knowledge as a result of the treatment using two instruments. The Learning Mathematics for Teaching scales were used to detect changes in mathematical knowledge for teaching, and an online sorting task was used to detect changes in teachers' knowledge of their standards. Results also indicated differences in classroom practice between pairs of matched teachers selected to participate in classroom observations and interviews. No statistical difference was detected between the groups' student assessment scores using the district's benchmark assessment system. This efficacy study contributes to the literature in two ways. First, it provides an evidence base for a professional development model designed to promote effective implementation of the Common Core State Standards for Mathematics. Second, it addresses ways to impact and measure teachers' knowledge of curriculum in addition to their mathematical content knowledge. The treatment was designed to focus on knowledge of curriculum, but it also successfully impacted teachers' specialized content knowledge, knowledge of content and students, and knowledge of content and teaching.
ContributorsRimbey, Kimberly A (Author) / Middleton, James A. (Thesis advisor) / Sloane, Finbarr (Committee member) / Atkinson, Robert K (Committee member) / Arizona State University (Publisher)
Created2013
Description
The purpose of this study was to investigate critical literacy practices in two prehistoric exhibits in a natural history museum. Bourdieu's habitus and Bakhtin's dialogism served as theoretical frames to collect and analyze data. Data were collected and triangulated using field notes, interview transcriptions, archives, and other data sources to critically scrutinize textual meaning and participant responses. Spradley's (1979) domain analysis was used to sort and categorize data in the early stage. Glaser and Strauss's (1967) constant comparative method was used to code data. My major findings were that museum texts within this context represent embedded beliefs and values that were interwoven with curators` habitus, tastes and capital, as well as institutional policies. The texts in the two Hohokam exhibits endorse a certain viewpoint of learning. Teachers and the public were not aware of the communicative role that the museum played in the society. In addition, museum literacy/ies were still practiced in a fundamental way as current practices in the classroom, which may not support the development of critical literacy. In conclusion, the very goal for critical museum literacy is to help students and teachers develop intellectual strategies to read the word and the world in informal learning environments.
ContributorsLiang, Sheau-yann (Author) / Mccarty, Teresa (Thesis advisor) / Marsh, Josephine (Committee member) / Blumenfeld-Jones, Donald (Committee member) / Welsh, Peter (Committee member) / Arizona State University (Publisher)
Created2013
Description
Concerted efforts have been made within teacher preparation programs to integrate teaching with technology into the curriculum. Unfortunately, these efforts continue to fall short as teachers' application of educational technology is unsophisticated and not well integrated. The most prevalent approaches to integrating technology tend to ignore pedagogy and content and assume that the technology integration knowledge for all contexts is the same. One theoretical framework that does acknowledge content, pedagogy, and context in conjunction with technology is Technological Pedagogical Content Knowledge (TPACK) and was the lens through which teacher development was measured and interpreted in this study. The purpose of this study was to investigate graduate teacher education students' knowledge and practice of teaching with technology as well as how that knowledge and practice changes after participation in an educational technology course. This study used a mixed-methods sequential explanatory research design in which both quantitative and qualitative data were gathered from 82 participants. TPACK pre- and postcourse surveys were administered to a treatment group enrolled in an educational technology course and to a nonequivalent control group enrolled in a learning theories course. Additionally, pre- and postcourse lesson plans were collected from the treatment group. Select treatment group participants also participated in phone interviews. Analyses compared pre- and post-course survey response differences within and between the treatment and control groups. Pre- and postlesson plan rubric score differences were compared within the treatment group. Quantitative text analyses were performed on the collected lesson plans. Open and axial coding procedures were followed to analyze interview transcripts. The results of the study revealed five significant findings: 1) graduate students entering an educational technology course reported lower ability in constructs related to teaching with technology than in constructs related to teaching in a traditional setting; 2) TPACK was malleable and TPACK instruments were sensitive to that malleability; 3) significant gains in reported and demonstrated TPACK constructs were found after participating in an educational technology course; 4) TPACK construct ability levels vary significantly by participant characteristics; and 5) influences on teaching knowledge and practice range from internet resources, to mentor teachers, and to standardized curriculum packages.
ContributorsSabo, Kent (Author) / Atkinson, Robert (Thesis advisor) / Archambault, Leanna (Committee member) / Savenye, Wilhelmina (Committee member) / Arizona State University (Publisher)
Created2013
Description
Multivariate forms of social oppression, such as racism, linguicism, and heterosexism, are manifested in schools that, as part of our communities, reflect the societal stratification and structural inequalities of a larger society. Teacher educators engaged in multicultural education are responsible for providing pre-service teachers with opportunities to critically examine the intricacies of cultural diversity in U.S. classrooms, developing critical multicultural dispositions. What are effective pedagogical strategies that encourage pre-service teachers to develop such critical multicultural practices? The researcher has found that participatory theatre, including Boalian theatre games, Forum Theatre, Image Theatre, and ethnodrama, can be a transformative, emancipatory pedagogical tool to engage students in critical and creative exploration of cultural diversity. The primary objective of this study is to illustrate how pre-service teachers develop critical consciousness through attending the researcher's multicultural teacher education classroom, which was designed at the nexus of Freirean and Boalian critical (performance) pedagogy, followed by analyzing his teaching practice, which focuses mainly on participatory theatre exercises. This doctoral dissertation is an ethnographic documentary of the researcher's striving to challenge the hegemonic status quo in teacher education by liberating himself from the anti-dialogical banking educator, and encouraging his students to liberate themselves as passive consumers of education. Such reflection may provide teacher educators with examples of counter-hegemonic (artistic) practice for social change relating to their own work.
ContributorsMitsumura, Masakazu (Author) / Tobin, Joseph (Thesis advisor) / Saldana, Johnny (Committee member) / Sterling, Pamela (Committee member) / Arizona State University (Publisher)
Created2012