Matching Items (43,913)
Description
ATP synthase is a large multimeric protein complex responsible for generating the energy molecule adenosine triphosphate (ATP) in most organisms. The catalysis involves the rotation of a ring of c-subunits, which is driven by the transmembrane electrochemical gradient. This dissertation reports how the eukaryotic c-subunit from spinach chloroplast ATP synthase has successfully been expressed in Escherichia coli and purified in mg quantities by incorporating a unique combination of methods. Expression was accomplished using a codon optimized gene for the c-subunit, and it was expressed as an attachment to the larger, more soluble, native maltose binding protein (MBP-c1). The fusion protein MBP-c1 was purified on an affinity column, and the c1 subunit was subsequently severed by protease cleavage in the presence of detergent. Final purification of the monomeric c1 subunit was accomplished using reversed phase column chromatography with ethanol as an eluent. Circular dichroism spectroscopy data showed clear evidence that the purified c-subunit is folded with the native alpha-helical secondary structure. Recent experiments appear to indicate that this monomeric recombinant c-subunit forms an oligomeric ring that is similar to its native tetradecameric form when reconstituted in liposomes. The F-type ATP synthase c-subunit stoichiometry is currently known to vary from 8 to 15 subunits among different organisms. This has a direct influence on the metabolic requirements of the corresponding organism because each c-subunit binds and transports one H+ across the membrane as the ring makes a complete rotation. The c-ring rotation drives rotation of the gamma-subunit, which in turn drives the synthesis of 3 ATP for every complete rotation. The availability of a recombinantly produced c-ring will lead to new experiments which can be designed to investigate the possible factors that determine the variable c-ring stoichiometry and structure.
ContributorsLawrence, Robert Michael (Author) / Fromme, Petra (Thesis advisor) / Chen, Julian J.L. (Committee member) / Woodbury, Neal W. (Committee member) / Arizona State University (Publisher)
Created2011
Description
Telomerase is a specialized enzyme that adds telomeric DNA repeats to the chromosome ends to counterbalance the progressive telomere shortening over cell divisions. It has two essential core components, a catalytic telomerase reverse transcriptase protein (TERT), and a telomerase RNA (TR). TERT synthesizes telomeric DNA by reverse transcribing a short template sequence in TR. Unlike TERT, TR is extremely divergent in size, sequence and structure and has only been identified in three evolutionarily distant groups. The lack of knowledge on TR from important model organisms has been a roadblock for vigorous studies on telomerase regulation. To address this issue, a novel in vitro system combining deep-sequencing and bioinformatics search was developed to discover TR from new phylogenetic groups. The system has been validated by the successful identification of TR from echinoderm purple sea urchin Strongylocentrotus purpuratus. The sea urchin TR (spTR) is the first invertebrate TR that has been identified and can serve as a model for understanding how the vertebrate TR evolved with vertebrate-specific traits. By using phylogenetic comparative analysis, the secondary structure of spTR was determined. The spTR secondary structure reveals unique sea urchin specific structure elements as well as homologous structural features shared by TR from other organisms. This study enhanced the understanding of telomerase mechanism and the evolution of telomerase RNP. The system that was used to identity telomerase RNA can be employed for the discovery of other TR as well as the discovery of novel RNA from other RNP complex.
ContributorsLi, Yang (Author) / Chen, Julian Jl (Thesis advisor) / Yan, Hao (Committee member) / Ghirlanda, Giovanna (Committee member) / Arizona State University (Publisher)
Created2011
Description
Many of the works of Dominick Argento have been researched and analyzed, but his choral work Evensong: Of Love and Angels s has received limited attention thus far. Written in memoriam for his wife Carolyn Bailey Argento, Evensong draws its musical material from her initials C.B.A. These letters, translated into note names, form a conspicuous head motive that is present in each movement of the work, and it serves multiple functions: as a melodic feature, as the foundation for a twelve-tone row, and as a harmonic base. This paper provides an overview of the work's conception with specific relation to Argento's biographical details, compositional style, and work habits; a brief review of the critical reception of the work; and a succinct analysis of the form and cyclical materials found in each movement.
ContributorsPage, Carrie Leigh, 1980- (Author) / Rogers, Rodney (Thesis advisor) / DeMars, James (Committee member) / Levy, Benjamin (Committee member) / Oldani, Robert (Committee member) / Arizona State University (Publisher)
Created2011
Description
Everyday Arias for soprano and orchestra was composed largely in Arizona and completed in February 2011. The text was taken from a small collection of the composer's own poetry referencing her memories of life in rural Mississippi. Everyday Arias endeavors to elevate these prosaic experiences and settings to art, expressing the everyday as beautiful and worthy of artistic treatment. The primary compositional model for this work was Samuel Barber's Knoxville: Summer of 1915, but other influences included Charles Ives, Aaron Copland, Benjamin Britten, and Dominick Argento. Barber's and Argento's musical treatment of prose style seemed particularly appropriate to the goals of Everyday Arias. Ives and Copland used hymn tunes both to evoke certain associations of worship and as sources of interesting material. The vocal writing of all five composers was influential, but the orchestration techniques for winds are largely a product of studying Ives and Argento, while many string gestures are more obviously tied to Britten and - more historically - Debussy.The primary motive that weaves through the work features an ascending major second followed by a descending perfect fourth, in a long-short-long rhythmic pattern. As a melodic fragment, the motive is often inverted to a descending-ascending pattern, or distorted slightly by expanding the second interval to a perfect fifth, or used in retrograde. The motive was derived from the first measure of the melody "Toplady" (1830) by Thomas Hastings, better known as the hymn "Rock of Ages." In the first movement, the motive is used most frequently in sequences. The second movement treats the motive as a melodic element and as a unit in ostinati. The final movement humorously transforms it into a syncopated gesture to evoke ragtime.
ContributorsPage, Carrie Leigh (Composer) / Rogers, Rodney (Thesis advisor) / DeMars, James (Committee member) / Levy, Benjamin (Committee member) / Oldani, Robert (Committee member) / Arizona State University (Publisher)
Created2011
Description
The nature of science (NOS) is included in the National Science Education Standards and is described as a critical component in the development of scientifically literate students. Despite the significance of NOS in science education reform, research shows that many students continue to possess naïve views of NOS. Explicit and reflective discussion as an instructional approach is relatively new in the field of research in NOS. When compared to other approaches, explicit instruction has been identified as more effective in promoting informed views of NOS, but gaps in student understanding still exist. The purpose of this study was to deepen the understanding of student learning of NOS through the investigation of two variations of explicit instruction. The subjects of the study were two seventh grade classes taught by the same classroom teacher. One class received explicit instruction of NOS within a plate tectonics unit and the second class received explicit instruction of NOS within a plate tectonics unit plus supporting activities focused on specific aspects of NOS. The instruction time for both classes was equalized and took place over a three week time period. The intention of this study was to see if the additional NOS activities helped students build a deeper understanding of NOS, or if a deep understanding could be formed solely through explicit and reflective discussion within content instruction. The results of the study showed that both classes progressed in their understanding of NOS. When the results of the two groups were compared, the group with the additional activities showed statistically significant gains on two of the four aspects of NOS assessed. These results suggest that the activities may have been valuable in promoting informed views, but more research is needed in this area.
ContributorsMelville, Melissa (Author) / Luft, Julie (Thesis advisor) / Baker, Dale (Committee member) / Brem, Sarah (Committee member) / Arizona State University (Publisher)
Created2011
ContributorsBurton, Charlotte (Performer) / ASU Library. Music Library (Publisher)
Created2018-04-08
Description
This study explores how grantmakers conceptualize their work with respect to issues of social justice. It seeks to answer two primary questions: What role, if any, does the philanthropic community ascribe to itself in not just ameliorating but helping solve our greatest social challenges? And if philanthropy does see itself as an agent of change, what are the barriers that limit its potential? After painting a portrait of contemporary American philanthropy, this paper applies Iris Marion Young's critique of distributive justice to philanthropy's dilemma between downstream charitable aid and upstream structural change. The thesis then turns to analysis of semi-structured interviews with eighteen of Arizona's foundation leaders to assess whether and how state-level philanthropic leaders see their work vis-á -vis social justice, and understand how external factors limit philanthropy's ability to effect maximum social change. Participants express a desire to engage in genuinely meaningful philanthropy which does more than just maintain the status quo, but identify multiple constraints, including legal barriers to fully utilizing advocacy as a tool, governmental infringement on philanthropic autonomy, the channeling of philanthropic resources toward basic needs as a result of the recession, and a grantmaking orientation that prioritizes short term programs that yield swift, measurable results as opposed to longer term efforts.
ContributorsLester, Eva Lorraine (Author) / Zatz, Marjorie S (Thesis advisor) / Haglund, LaDawn (Committee member) / Romero, Mary (Committee member) / Arizona State University (Publisher)
Created2011
Description
This study contributes to the ongoing discussion of Mathematical Knowledge for Teaching (MKT). It investigates the case of Rico, a high school mathematics teacher who had become known to his colleagues and his students as a superbly effective mathematics teacher. His students not only developed excellent mathematical skills, they also developed deep understanding of the mathematics they learned. Moreover, Rico redesigned his curricula and instruction completely so that they provided a means of support for his students to learn mathematics the way he intended. The purpose of this study was to understand the sources of Rico's effectiveness. The data for this study was generated in three phases. Phase I included videos of Rico's lessons during one semester of an Algebra II course, post-lesson reflections, and Rico's self-constructed instructional materials. An analysis of Phase I data led to Phase II, which consisted of eight extensive stimulated-reflection interviews with Rico. Phase III consisted of a conceptual analysis of the prior phases with the aim of creating models of Rico's mathematical conceptions, his conceptions of his students' mathematical understandings, and his images of instruction and instructional design. Findings revealed that Rico had developed profound personal understandings, grounded in quantitative reasoning, of the mathematics that he taught, and profound pedagogical understandings that supported these very same ways of thinking in his students. Rico's redesign was driven by three factors: (1) the particular way in which Rico himself understood the mathematics he taught, (2) his reflective awareness of those ways of thinking, and (3) his ability to envision what students might learn from different instructional approaches. Rico always considered what someone might already need to understand in order to understand "this" in the way he was thinking of it, and how understanding "this" might help students understand related ideas or methods. Rico's continual reflection on the mathematics he knew so as to make it more coherent, and his continual orientation to imagining how these meanings might work for students' learning, made Rico's mathematics become a mathematics of students--impacting how he assessed his practice and engaging him in a continual process of developing MKT.
ContributorsLage Ramírez, Ana Elisa (Author) / Thompson, Patrick W. (Thesis advisor) / Carlson, Marilyn P. (Committee member) / Castillo-Chavez, Carlos (Committee member) / Saldanha, Luis (Committee member) / Middleton, James A. (Committee member) / Arizona State University (Publisher)
Created2011
Description
Services outsourcing is a prevalent yet problematic phenomenon. On the one hand, more and more firms are outsourcing services function. On the other hand, we are faced with many services outsourcing failures. This research attempts to uncover some of the omitted causes of services outsourcing failure. It extends a conceptual paper that used social network theory to examine the shifting of the triadic relationship structures among the service buyer, service supplier and the buyer's customers at different stages of the services outsourcing arrangements and its performance implications. This study empirically examines these performance implications. Specifically, this research defines the concept of bridge transfer, which denotes the weakening and dissolution of operational ties between the service buyer firms' and their end customers and the appearing and strengthening of operational ties between the service supplier firms and the end customers. It also empirically derives a measurement scale for this new construct. Further, the effects of bridge transfer on supplier's appropriation behavior, buyer's cost of quality and end customers' quality perception are examined in the context of customer facing services and are contrasted with those entail little or no customer interactions. In addition, the moderating roles of buyer-supplier relationship on the effects of bridge transfer are also examined. An Internet-based survey was administered to firms affiliated with CAPS Research and the Institute of Supply Management as the primary data source (n=137). Principal Component Analyses were used to derive a composite score for each of the model construct. Then linear regressions were used to detect the effects of bridge transfer on services outsourcing outcomes and to detect the moderating role of buyer-supplier relationships on these effects. The results show that bridge transfer is positively correlated to suppliers' appropriate behavior and negatively correlated to end customer's quality perception in the context of customer facing services. The effects of bridge transfer are not found for services that entail little or no interactions with the end customers. Instead, buyer-supplier relationship is found to be a key influencing factor to services outsourcing outcomes in this context. This study helps to pinpoint some of the omitted causes of services outsourcing failures and shed light on how to manage services outsourcing for success.
ContributorsLi, Mei (Author) / Choi, Thomas Y. (Thesis advisor) / Dooley, Kevin J (Committee member) / Bitner, Mary-Jo (Committee member) / Arizona State University (Publisher)
Created2011
Description
With the advent of technologies such as web services, service oriented architecture and cloud computing, modern organizations have to deal with policies such as Firewall policies to secure the networks, XACML (eXtensible Access Control Markup Language) policies for controlling the access to critical information as well as resources. Management of these policies is an extremely important task in order to avoid unintended security leakages via illegal accesses, while maintaining proper access to services for legitimate users. Managing and maintaining access control policies manually over long period of time is an error prone task due to their inherent complex nature. Existing tools and mechanisms for policy management use different approaches for different types of policies. This research thesis represents a generic framework to provide an unified approach for policy analysis and management of different types of policies. Generic approach captures the common semantics and structure of different access control policies with the notion of policy ontology. Policy ontology representation is then utilized for effectively analyzing and managing the policies. This thesis also discusses a proof-of-concept implementation of the proposed generic framework and demonstrates how efficiently this unified approach can be used for analysis and management of different types of access control policies.
ContributorsKulkarni, Ketan (Author) / Ahn, Gail-Joon (Thesis advisor) / Yau, Stephen S. (Committee member) / Huang, Dijiang (Committee member) / Arizona State University (Publisher)
Created2011