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Description
Pathogenic Gram-negative bacteria employ a variety of molecular mechanisms to combat host defenses. Two-component regulatory systems (TCR systems) are the most ubiquitous signal transduction systems which regulate many genes required for virulence and survival of bacteria. In this study, I analyzed different TCR systems in two clinically-relevant Gram-negative bacteria, i.e., oral pathogen Porphyromonas gingivalis and enterobacterial Escherichia coli. P. gingivalis is a major causative agent of periodontal disease as well as systemic illnesses, like cardiovascular disease. A microarray study found that the putative PorY-PorX TCR system controls the secretion and maturation of virulence factors, as well as loci involved in the PorSS secretion system, which secretes proteinases, i.e., gingipains, responsible for periodontal disease. Proteomic analysis (SILAC) was used to improve the microarray data, reverse-transcription PCR to verify the proteomic data, and primer extension assay to determine the promoter regions of specific PorX regulated loci. I was able to characterize multiple genetic loci regulated by this TCR system, many of which play an essential role in hemagglutination and host-cell adhesion, and likely contribute to virulence in this bacterium. Enteric Gram-negative bacteria must withstand many host defenses such as digestive enzymes, low pH, and antimicrobial peptides (AMPs). The CpxR-CpxA TCR system of E. coli has been extensively characterized and shown to be required for protection against AMPs. Most recently, this TCR system has been shown to up-regulate the rfe-rff operon which encodes genes involved in the production of enterobacterial common antigen (ECA), and confers protection against a variety of AMPs. In this study, I utilized primer extension and DNase I footprinting to determine how CpxR regulates the ECA operon. My findings suggest that CpxR modulates transcription by directly binding to the rfe promoter. Multiple genetic and biochemical approaches were used to demonstrate that specific TCR systems contribute to regulation of virulence factors and resistance to host defenses in P. gingivalis and E. coli, respectively. Understanding these genetic circuits provides insight into strategies for pathogenesis and resistance to host defenses in Gram negative bacterial pathogens. Finally, these data provide compelling potential molecular targets for therapeutics to treat P. gingivalis and E. coli infections.
ContributorsLeonetti, Cori (Author) / Shi, Yixin (Thesis advisor) / Stout, Valerie (Committee member) / Nickerson, Cheryl (Committee member) / Sandrin, Todd (Committee member) / Arizona State University (Publisher)
Created2013
Description
The study of bacterial resistance to antimicrobial peptides (AMPs) is a significant area of interest as these peptides have the potential to be developed into alternative drug therapies to combat microbial pathogens. AMPs represent a class of host-mediated factors that function to prevent microbial infection of their host and serve as a first line of defense. To date, over 1,000 AMPs of various natures have been predicted or experimentally characterized. Their potent bactericidal activities and broad-based target repertoire make them a promising next-generation pharmaceutical therapy to combat bacterial pathogens. It is important to understand the molecular mechanisms, both genetic and physiological, that bacteria employ to circumvent the bactericidal activities of AMPs. These understandings will allow researchers to overcome challenges posed with the development of new drug therapies; as well as identify, at a fundamental level, how bacteria are able to adapt and survive within varied host environments. Here, results are presented from the first reported large scale, systematic screen in which the Keio collection of ~4,000 Escherichia coli deletion mutants were challenged against physiologically significant AMPs to identify genes required for resistance. Less than 3% of the total number of genes on the E. coli chromosome was determined to contribute to bacterial resistance to at least one AMP analyzed in the screen. Further, the screen implicated a single cellular component (enterobacterial common antigen, ECA) and a single transporter system (twin-arginine transporter, Tat) as being required for resistance to each AMP class. Using antimicrobial resistance as a tool to identify novel genetic mechanisms, subsequent analyses were able to identify a two-component system, CpxR/CpxA, as a global regulator in bacterial resistance to AMPs. Multiple previously characterized CpxR/A members, as well as members found in this study, were identified in the screen. Notably, CpxR/A was found to transcriptionally regulate the gene cluster responsible for the biosynthesis of the ECA. Thus, a novel genetic mechanism was uncovered that directly correlates with a physiologically significant cellular component that appears to globally contribute to bacterial resistance to AMPs.
ContributorsWeatherspoon-Griffin, Natasha (Author) / Shi, Yixin (Thesis advisor) / Clark-Curtiss, Josephine (Committee member) / Misra, Rajeev (Committee member) / Nickerson, Cheryl (Committee member) / Stout, Valerie (Committee member) / Arizona State University (Publisher)
Created2013
Description
The contemporary architectural pedagogy is far removed from its ancestry: the classical Beaux-Arts and polytechnic schools of the 19th century and the Bauhaus and Vkhutemas models of the modern period. Today, the "digital" has invaded the academy and shapes pedagogical practices, epistemologies, and ontologies within it, and this invasion is reflected in teaching practices, principles, and tools. Much of this digital integration goes unremarked and may not even be explicitly taught. In this qualitative research project, interviews with 18 leading architecture lecturers, professors, and deans from programs across the United States were conducted. These interviews focused on advanced practices of digital architecture, such as the use of digital tools, and how these practices are viewed. These interviews yielded a wealth of information about the uses (and abuses) of advanced digital technologies within the architectural academy, and the results were analyzed using the methods of phenomenology and grounded theory. Most schools use digital technologies to some extent, although this extent varies greatly. While some schools have abandoned hand-drawing and other hand-based craft almost entirely, others have retained traditional techniques and use digital technologies sparingly. Reasons for using digital design processes include industry pressure as well as the increased ability to solve problems and the speed with which they could be solved. Despite the prevalence of digital design, most programs did not teach related design software explicitly, if at all, instead requiring students (especially graduate students) to learn to use them outside the design studio. Some of the problems with digital design identified in the interviews include social problems such as alienation as well as issues like understanding scale and embodiment of skill.
ContributorsAlqabandy, Hamad (Author) / Brandt, Beverly (Thesis advisor) / Mesch, Claudia (Committee member) / Newton, David (Committee member) / Arizona State University (Publisher)
Created2012
Description
In the middle of the 20th century, juried annuals of Native American painting in art museums were unique opportunities because of their select focus on two-dimensional art as opposed to "craft" objects and their inclusion of artists from across the United States. Their first fifteen years were critical for patronage and widespread acceptance of modern easel painting. Held at the Philbrook Art Center in Tulsa (1946-1979), the Denver Art Museum (1951-1954), and the Museum of New Mexico Art Gallery in Santa Fe (1956-1965), they were significant not only for the accolades and prestige they garnered for award winners, but also for setting standards of quality and style at the time. During the early years of the annuals, the art was changing, some moving away from conventional forms derived from the early art training of the 1920s and 30s in the Southwest and Oklahoma, and incorporating modern themes and styles acquired through expanded opportunities for travel and education. The competitions reinforced and reflected a variety of attitudes about contemporary art which ranged from preserving the authenticity of the traditional style to encouraging experimentation. Ultimately becoming sites of conflict, the museums that hosted annuals contested the directions in which artists were working. Exhibition catalogs, archived documents, and newspaper and magazine articles about the annuals provide details on the exhibits and the changes that occurred over time. The museums' guidelines and motivations, and the statistics on the award winners reveal attitudes toward the art. The institutions' reactions in the face of controversy and their adjustments to the annuals' guidelines impart the compromises each made as they adapted to new trends that occurred in Native American painting over a fifteen year period. This thesis compares the approaches of three museums to their juried annuals and establishes the existence of a variety of attitudes on contemporary Native American painting from 1946-1960. Through this collection of institutional views, the competitions maintained a patronage base for traditional style painting while providing opportunities for experimentation, paving the way for the great variety and artistic progress of Native American painting today.
ContributorsPeters, Stephanie (Author) / Duncan, Kate (Thesis advisor) / Fahlman, Betsy (Thesis advisor) / Mesch, Claudia (Committee member) / Arizona State University (Publisher)
Created2012
Description
This project is a critical look at Chicano artist Vincent Valdez's 2002-2004 series Stations. The theoretical framework for this work is the concept of cultural citizenship, which refers to a variety of ways in which marginalized groups of people create, fight for, and retain space, identity, and rights within American society through acts of daily life. This research considers how the ten large-scale charcoal drawings that comprise Stations contribute to the construction and representation of distinct and unique Latino spaces and identities. Valdez establishes space in the sense of belonging and community engagement that his work allows. Within this context, thoughtful attention is paid to the cultural meaning of the artist's subject choices of boxing and religion. This research considers the significance of these subject choices and how the connections between the two create unique spaces of shared experience and consciousness for a viewer of the work. However, the parallels that Valdez draws between the Christ figure and his boxer also allow for a careful examination of the representations and contradictions of contemporary constructions of masculinity that are present in the series. Within this project, the work of Gloria Anzaldúa is critical in understanding and discussing the fluid nature of Chicano identity. This study also considers how in the tradition of Chicana writers, Valdez expresses and affirms identity through autobiographical methods. Further, the artist's use of charcoal to create these large scale drawings is considered for its narrative qualities. This study concludes that Valdez's series Stations is an act of cultural citizenship.
ContributorsStemm Patel, Shannon (Author) / Malagamba-Ansótegui, Amelia (Thesis advisor) / Mesch, Claudia (Committee member) / Sweeney, Gray (Committee member) / Arizona State University (Publisher)
Created2010
Description
The Indian princess began as an imposition, a Eurocentric conception based in preconceived notions of cultural structures and gendered power roles - a mixture of noble woman and provocative demure maiden - created by Anglo men to epitomize an idyllic image of otherness and womanhood. This analysis begins by exploring the history of the icon that was first conceived through sixteenth century explorer's tales of exotic queens then traces her progression through the romantic idealizations of the Indian woman Pocahontas. Research then explores how the character, comprised of a mixture of feathers, beads, and buckskin, was implemented into performance, and discusses how her flesh and blood enactment became critical to her survival. Drawing on the theories of contemporary critics, final examination turns to twentieth century perceptions of the Princess and reactions to her by contemporary Native artists whose manipulations of the character opens alternative dialogs about the stereotype to offer reconstructions of her historic discourse.
ContributorsHanawalt, Tammi Jo (Author) / Duncan, Kate (Thesis advisor) / Fahlman, Betsy (Committee member) / Malagamba-Ansótegui, Amelia (Committee member) / Mesch, Claudia (Committee member) / Arizona State University (Publisher)
Created2011
Description
The dissertation focuses on several Romanian avant-garde magazines, such as Contimporanul, Integral, and 75HP, that Romanian artists and writers created in Romania in the 1920s, after Romanian Dadaists Tristan Tzara and Marcel Iancu disbanded from Zurich Dada in the 1910s. The Romanian avant-garde magazines launched the Romanian avant-garde movement—the most intense period of artistic production in the country. The Romanian avant-gardists established Integralism in an attempt to differentiate themselves from other European avant-garde groups and to capture the intense and innovative creative spirit of their modern era by uniting and condensing avant-garde and modern styles on the pages of their magazines. However, I argue that instead of Integralism, what the Romanian avant-garde magazines put forth were Romanian avant-garde versions of Constructivism and Cubism conveyed in the magazines’ constructivist prints and reproductions of cubist paintings. The originality of the Romanian avant-garde magazines, thus, is concentrated in their appropriation and reinterpretation of Constructivism and Cubism rather than in their Integralism. Moreover, in their rebellion and resistance to Romania’s social, political, and artistic status quo, the Romanian avant-garde magazines functioned as an instrument with which the Romanian avant-gardists expressed their complex relationship with their Jewish identity. The magazines were not on the periphery of artistic production, as art history discourse on modern and avant-garde art has situated them, but were an important player in the global network of avant-garde magazines that traversed across eastern and western Europe, South America, the United States, and Japan.
ContributorsMiholca, Amelia (Author) / Mesch, Claudia (Thesis advisor) / Orlich, Ileana (Committee member) / Holian, Anna (Committee member) / Navarro, Rudy (Committee member) / Arizona State University (Publisher)
Created2021
Description
Traditional Reinforcement Learning (RL) assumes to learn policies with respect to reward available from the environment but sometimes learning in a complex domain requires wisdom which comes from a wide range of experience. In behavior based robotics, it is observed that a complex behavior can be described by a combination of simpler behaviors. It is tempting to apply similar idea such that simpler behaviors can be combined in a meaningful way to tailor the complex combination. Such an approach would enable faster learning and modular design of behaviors. Complex behaviors can be combined with other behaviors to create even more advanced behaviors resulting in a rich set of possibilities. Similar to RL, combined behavior can keep evolving by interacting with the environment. The requirement of this method is to specify a reasonable set of simple behaviors. In this research, I present an algorithm that aims at combining behavior such that the resulting behavior has characteristics of each individual behavior. This approach has been inspired by behavior based robotics, such as the subsumption architecture and motor schema-based design. The combination algorithm outputs n weights to combine behaviors linearly. The weights are state dependent and change dynamically at every step in an episode. This idea is tested on discrete and continuous environments like OpenAI’s “Lunar Lander” and “Biped Walker”. Results are compared with related domains like Multi-objective RL, Hierarchical RL, Transfer learning, and basic RL. It is observed that the combination of behaviors is a novel way of learning which helps the agent achieve required characteristics. A combination is learned for a given state and so the agent is able to learn faster in an efficient manner compared to other similar approaches. Agent beautifully demonstrates characteristics of multiple behaviors which helps the agent to learn and adapt to the environment. Future directions are also suggested as possible extensions to this research.
ContributorsVora, Kevin Jatin (Author) / Zhang, Yu (Thesis advisor) / Yang, Yezhou (Committee member) / Praharaj, Sarbeswar (Committee member) / Arizona State University (Publisher)
Created2021
Description
The Hong Kong-born Canadian photographer and performance artist Tseng Kwong Chi mostly worked in the United States until the year he died in 1990. Upon arriving in New York in 1979, he started his career with a new name. By dropping his anglicized name Joseph and replacing it with his Chinese given name Kwong Chi, Tseng made a clear statement: this is my staged persona who refuses to assimilate to Western culture. This thesis deconstructs Tseng’s key works, including his party-crashing Met series, the decade-long East Meets West series, and the extended Expeditionary series. With his persona disguised by wearing a Mao suit and a pair of sunglasses, I argue that Tseng was a pioneer in the genre of Asian American performance photography and that his work foreshadowed the cultural jamming movement in his innovative use of détournement while it also critically comments on orientalism, cultural fetish, and Asian identity politics. Additionally, Tseng’s work served as a bridge, connecting art history with issues of Asian American identity. As a gay artist who worked mostly in the United States, his work was an early example of what Jachinson Chan has suggested as an alternative model of masculinity for Asian American men: that Asian American men can be free, independent, expressive, and willing to embrace femininity with their masculinity. As David Eng has argued, Tseng also bridged the fields of Asian American queer studies and diaspora studies. Moreover, Tseng carried the legacy of the first-generation Chinese American artists in the medium of photography and inspired the next generation of diasporic artists to explore Asian identity, and to contest the image of Mao and the power dynamics between East and West.
ContributorsWei, Xin (Author) / Mesch, Claudia (Thesis advisor) / Hoy, Meredith (Committee member) / Kuo, Karen (Committee member) / Arizona State University (Publisher)
Created2022
Description
This dissertation consists of three chapters that investigate the rapid adoption and complex implementation of city commitments to transition to 100% renewable energy (100RE). The first paper uses a two-stage, mixed methods approach to examine 100RE commitments across the US, combining a multivariate regression of demographic, institutional, and policy factors in adoption and six interview-based state case studies to discuss implementation. Adoption of this non-binding commitment progressed rapidly for city councils around the US. Results show that many cities passed 100RE commitments with no implementation plan and minimal understanding of implementation challenges. This analysis highlights that many cities will need new institutions and administrative capacities for successful implementation of these ambitious new policies. While many cities abandoned the commitment soon after adoption, collaboration allowed cities in a few states to break through and pursue implementation, examined further in the next two studies. The second paper is a qualitative case study examining policymaking for the Utah Community Renewable Energy Act. Process tracing methods are used to identify causal factors in enacting this legislation at the state level and complementary resolutions at the local level. This Act was passed through the leadership and financial backing of major cities and committed the investor-owned utility to fulfill any city 100RE resolutions passed through 2019. Finally, the third paper is a mixed-methods, descriptive case study of the benefits of Community Choice Aggregation (CCA) in California, which many cities are using to fulfill their 100RE commitments. Cities have adopted CCAs to increase their local voice in the energy process, while fulfilling climate and energy goals. Overall, this research shows that change in the investor-owned utility electricity system is in fact possible from the city scale, though many cities will need institutional innovation to implement these policies and achieve the change they desire. While cities with greater resources are better positioned to make an impact, smaller cities can collaborate to similarly influence the energy system. Communities are interested in lowering energy costs for customers where possible, but the central motivations in these cases were the pursuit of sustainability and increasing local voice in energy decision-making.
ContributorsKunkel, Leah Christine (Author) / Breetz, Hanna L (Thesis advisor) / Parker, Nathan (Committee member) / Salon, Deborah (Committee member) / Arizona State University (Publisher)
Created2022