Now showing items 8982-9001 of 20274

    • I already know how to read.: Literacy through the eyes and mind of a child

      Martens, Prisca Amalia.; Goodman, Yetta M.; Goodman, Kenneth S.; McCarty, Teresa; Short, Kathy G.; Fox, Dana (The University of Arizona., 1994)
      Sarah's literacy from ages 2-5 is documented through this longitudinal interpretative case study. The researcher, Sarah's mother, employed ethnographic techniques and methodologies of data analysis and data collection, including interviews, writing samples, audiotapes, observations, and field notes, to accomplish the research goals and purposes. The initial research goals were twofold: (a) to observe and describe Sarah's literacy in natural settings, particularly at home, beginning formally at age 2; and (b) to analyze, understand, and explain her literacy learning process. The model of literacy learning presented, the generative learning cycle, is grounded and rooted in both the data and the theory and research of others, notably Ken Goodman, Yetta Goodman, and Kathy Short. The data demonstrate that Sarah's learning is continuous and not hierarchically ordered as developmental stages propose. While the qualities of her literacy artifacts, or products, change, the quality of her thinking, strategies, and learning process do not. She perceives, questions, and invents sophisticated solutions to her inquiries concerning literacy, continually utilizing all she knows to outgrow herself and learn what she does not know.
    • I Came Through You and Belong Not to You: Overparenting, Attachment, Autonomy, and Mental Health at Emerging Adulthood

      Segrin, Chris C.S.; Jiao, Jian; Harwood, Jake J.H.; Rains, Steve S.R. (The University of Arizona., 2022)
      Research on overparenting (a.k.a. helicopter parenting) shows that it is associated with many negative qualities of the parent and the child, among which is mental distress. Guided by attachment theory, self-determination theory, bidirectional effects in parenting and child characteristics, and interpersonal theories of mental health, the present studies examined the cross-sectional and longitudinal associations between overparenting and the mental health of both emerging adults and their parents as well as associated mechanisms. Study 1 was a six-month longitudinal study and collected data from American parents and emerging adult children. Results showed that overparenting prospectively predicted emerging adults’ attachment avoidance in romantic relationships. Moreover, emerging adults’ mental distress prospectively predicted overparenting, but not vice versa. For parents, neither prospective nor cross-sectional associations were observed between parental mental distress and overparenting. Study 2 was a cross-sectional study and collected data from 196 Chinese emerging adults. Results showed that overparenting was positively associated with child mental distress, and this effect was mediated by unfulfilled psychological needs. Altogether, the findings from the present studies suggest overparenting as a response to child mental distress during emerging adulthood, and the effect from overparenting on child mental distress might be more temporary than enduring, if any. Parental mental distress was not associated with overparenting.
    • I Found It, I Liked It, I Taught It: Preservice Art Teachers’ Use and Transformation of Online Resources in Curriculum Development

      Shin, Ryan; Stuart, Kasey Elizabeth; DiCindio, Carissa; Wilson, Gloria; Carter, Kathy (The University of Arizona., 2022)
      This study aimed to understand how and why social media and other online platforms are used as curricular resources by preservice teachers during their semester of student teaching. Furthermore, the study examined how preservice art teachers critically analyzed and transformed their approach to using online sources through the use of a curricular intervention. In service of these aims, the following research questions were asked: How do preservice art teachers employ social media and online platforms as resources in their lesson plans at the outset of student teaching? After engaging with an intervention on critically assessing online-based lesson plans, how do preservice art teachers reflect upon and/or transform their own lesson plans? In this process, how do participants transform the original intervention? How does the process of finding, analyzing, and redesigning lesson plans found online and via social media transform the participants’ approach to designing curriculum? Addressing these questions, I implemented transformative learning theory (Cranton, 2016; Mezirow, 1997) to serve as the framework of the study, as this theory recognizes that while meaningful cognitive and behavioral transformations are the sole responsibility of the individual learner, such moments of transformation are greatly aided through learner empowerment and dialogue strategies. During this research, I served as the instructor of a student teaching seminar at a large, public university in the Southwestern United States that met six times over the course of a 16-week semester. Utilizing a design-based research methodology (Bakker, 2019; Crippen & Brown, 2018; The Design Based Research Collective, 2003) informed by co-operative inquiry (Heron & Reason, 2001), the study engaged four preservice art teachers enrolled in their semester of student teaching in a curricular intervention known as the Lesson Planning Activity (LPA). The LPA evolved as it was implemented and amended over three cycles of development, each of which illuminated the participants’ use of online resources for lesson plan development, their perceptions of the usefulness of the curricular intervention itself, and their changes to the LPA. Research data consisted of seminar discussion audio and video recordings, participants’ written feedback to the LPA’s (including written reflections, revised lesson plans, and example artworks), written responses to in-class activities, individual summative interviews, co-designed iterations of the LPA, and researcher reflective notes. Employing narrative data analysis, I constructed storied representations of each participant’s transformative journey through the semester, as well as a narrative retelling of the transformations underwent by the LPA itself. Individual participant stories were then analyzed and discussed as a whole, illuminating similarities and differences in online habits regarding lesson planning, especially between Elementary and Secondary preservice teachers. The story of the LPA culminated in describing a prototype application called The Art of Lesson Planning, which serves as the final iteration of the original LPA. Through developing a prototype app, participants not only aided in the complete transformation of the original LPA, but also sought to make publicly available the critical framework that helped them to 1) assess and transform their own lesson plans, 2) assess the usability of lesson plans found via online sources, and 3) have digital access to quality lesson plans. My analysis of the research findings indicated the following: First, all participants initially utilized social media and online resources to seek out lesson plans and/or curricular inspirations steeped in technique-driven traditional discourses (Thomas, 2020), voicing no interest in searching for topics related to expansive discourses, such as social justice, multiculturalism, diversity, equity, or inclusivity. This initial stance was transformed by the end of the semester. Second, while the LPA itself, as an isolated written and reflection-based activity, did not spur dramatic transformations to the original lesson plans found online, the LPA paired with long-form seminar discussions enabled a transformation of each participant’s preference for traditional discourse-aligned lessons to those which embody expansive discourses. Third, the thoughts, values, needs, and suggestions voiced by the participants were vital in creating a curricular intervention deemed helpful and usable by its’ intended users. Fourth, group discussion sessions were the most powerful force in helping participants critically self-reflect upon their curricular decisions and subsequently transform their approaches to designing lessons that were more integrative of student experience, conceptual depth, diverse artists, and varied subject matter. It is this fourth and final finding that led to the most vital contribution of this research, a prototheory of discourse-based lesson planning strategies for preservice art teachers.
    • "I Have a Connection!": The Situated Sense-Making of an Elementary Student about the Role of Water in Modeled vs. Experienced Ecosystems

      Johnson, Bruce; N. Roberts, Lisa (Elisabeth); Johnson, Bruce; Doyle, Walter; Gunckel, Kristin; Wood, Marcy (The University of Arizona., 2016)
      Current policy and research have led the field of science education towards a model of "science as practice." In the past decade, several research programs on model-based reasoning practices in education have articulated key dimensions of practice, including constructing and defending models, comparing models to empirical data, using representations to identify patterns in data and use those as inscriptions to buttress arguments. This study presents a detailed case of how the use of a physical microcosm and children's self-directed representations of an ecosystem constrained and afforded student sense-making in an urban elementary classroom. The case analyzed the experiences of a 10-year old fifth grade student, Jorge, and the variation in his expressed understanding of ecosystems as he interacted with academic tasks, along with models and representations, to design, observe and explain an ecological microcosm. The study used a conceptual framework that brings together theories of situated cognition and Doyle's work on academic task to explain how and why Jorge's perception and communication of dimensions of ecosystem structure, function, and behavior appear to "come in and out of focus," influenced by the affordances of the tools and resources available, the academic task as given by the teacher, and Jorge's own experiences and knowledge of phenomena related to ecosystems. Findings from this study suggest that elementary students' ability or inability to address particular ecological concepts in a given task relate less to gaps in their understanding and more to the structure of academic tasks and learning contexts. The process of a student interacting with curriculum follows a dynamic trajectory and leads to emergent outcomes. As a result of the complex interactions of task, tools, and his own interests and agency, Jorge's attunement to the role of water in ecosystems comes in and out of focus throughout the unit. The instructional constraint of needing to integrate the FOSS Water Cycle curriculum into the Bottle Biology Project became an affordance for Jorge to ask questions, observe, and theorize about the role of water and the water cycle in an ecosystem. The practice of modeling a closed ecosystem made salient to Jorge the boundaries of a system and the conservation of water within that system. The closed ecosystem model also presented constraints to students' sense making about the role of interactions when students lack domain knowledge in ecology. Relying on students' own talk, photographs and representations as explanations of phenomena in the Bio Bottle, without establishing norms of representational conventions and communication, resulted in missed opportunities for Jorge to reinforce his sense making during the activity and to develop conventions of scientific representation. Findings from this study can be used to inform the design and implementation of learning environments and curricular activities for elementary and middle school students that address all three dimensions of the Next Generation Science Standards: a) developing conceptual understanding of key concepts in the domain of ecology, b) the cross-cutting concept of systems, and c) multiple practices that ecologists use in developing and evaluating models that explain ecosystem structures, functions, and change over time.
    • I have a new friend in me: The effect of a multicultural/anti-bias curriculum on the development of social cognition in preschoolers

      Slaughter, Sheila; Rosenzweig, Jill Ellen (The University of Arizona., 1998)
      The purpose of this study was to investigate the early childhood program at the Tucson Jewish Community Center in order to discover the program's role in reproducing or restructuring the social order existing in the wider society. The study examined events in which issues of race, gender, class, and physical or mental disabilities arose in centers, during teacher guided group activities, at lunch, on the playground, and during other special activities among the groups of three and four year old children in the Center's preschool. The research then reviewed how young children develop social cognition and how they construct an understanding of their identity while developing expectations about individual and group behavior. It went on to investigate the manner in which race, gender, class, and disabilities issues were expressed and lived out by the children and staff. The data indicated that all four topics had meaning for the children, but issues involving race and gender arose more frequently than issues involving class and disabilities. The main source of information for this study were vignettes recorded in the three and four year old classrooms. The vignettes revealed the extent of the anti-bias perspective guiding the actions of both the staff and children and provided the data to evaluate the effect of the anti-bias curriculum presently in use at the preschool. The findings indicated that while an anti-bias perspective guided the resolution of many issues, it was not pervasive among all the children and staff. The findings also illustrated when an anti-bias perspective was guiding the formal curriculum. The major focus of the research questions was to determine the need for further staff training in order to develop a pervasive anti-bias perspective among the staff and children. The data indicated that additional staff training would be beneficial. Additional staff training should address the anti- bias perspective of the participants and the children. It should also explore ways to expand this perspective within the formal curriculum so that the curriculum stresses a democratic multicultural perspective.
    • "I lost the bus: Can you give me a ride home?" Native and nonnative English speakers' speech act production and metapragmatic judgments: A study of apologies, complaints and requests

      Wildner-Bassett, Mary E.; Ruhil, Anuradha, 1965- (The University of Arizona., 1998)
      This dissertation reports the findings of a study on pragmatic ability and metapragmatic judgments of native and nonnative speakers of English conducted at a public university in the United States and also at a public university in Singapore. Specifically, the research study investigated the realization of apologies, complaints and requests focusing on the production of downgraders and upgraders. In addition, the study also examined metapragmatic ratings provided by these subjects and their reasons for the ratings. Thirty-eight native and thirty nonnative speakers participated in the first phase of the study, which involved responding to a 30-item discourse completion task (DCT). In the second phase of data collection, responses to the DCT were used to construct a metapragmatic judgment task (MJT) in order to investigate subjects' metapragmatic ratings of apologies, complaints and requests. A new group of native speakers (69 total) and thirty-seven nonnative speakers (a new but comparable group) completed the MJT (the Singaporean subjects were unavailable for participation in the MJT). Fourteen native and 16 nonnative speakers participated in the interviews. Various statistical tests were conducted to analyze the coded DCT responses as well as the MJT data. Interview protocols were summarized to study opinions provided by subjects for the MJT ratings. Results of this research study indicated that native speakers used a significantly higher number of downgraders in complaints and requests than nonnative speakers. A significantly higher number of downgraders were also supplied in requests than in complaints. Metapragmatic ratings of native speakers differed significantly from those of nonnative speakers in 29/90 cases. While the two groups were significantly different in their performance on the DCT and the MJT, the subjective opinions expressed about the appropriateness of responses converged to a great extent. In conclusion, this dissertation was able to contribute to our understanding of native and nonnative speakers' use of modality markers and their perceptions about appropriate language use. The results of this study also concur with previous research that indicates the need for instruction in pragmatic aspects of the L2.
    • I Still Play: Exploring Play and Creativity in Early Adulthood Amongst Science, Technology, Engineering, Arts, and Mathematics Professionals

      Levine-Donnerstein, Deborah; Earl, Emily Charlotte; Levine-Donnerstein, Deborah; Burross, Heidi; Gaches, Sonya; Lopez, Francesca (The University of Arizona., 2015)
      Play is acknowledged as a fundamental need and right of the human experience. However, across the human lifespan is not always valued. Research on play has traditionally been on children, and while some attention is now being paid to older adults, there is little scholarship regarding play in adulthood. This exploratory study examined how early adulthood (25-40 years old) play, the influence playing has on creativity and career performance, and implications for future research on play. The study was completed utilizing traditional and non-traditional research methods with the intent to incorporate the participants' voice and perspectives into a human-centered research design. The end results of this study, demonstrated that early adults engage in a number of play experiences that shape their development and learning as well as influence their creativity and work performance. The use of human-centered research provided participants with the opportunity to individualize data collection, analyze results, and have a voice in the final product.
    • "I Thought this U.S. Place was Supposed to be About Freedom": Young Latinas Speak to Equity in Mathematics Education and Society

      Turner, Erin E; Gonzalez, Norma; Varley Gutierrez, Maura; Turner, Erin E; Gonzalez, Norma; Moll, Luis; Civil, Marta (The University of Arizona., 2009)
      This dissertation outlines findings from a critical ethnographic research study that attempted to document young Latinas engaging in critical mathematics education, with implications for shifting dominant ideas about the form and goals of education. As Latina youth are marginalized from classrooms and in society where their language, culture, practices, and community are seen as "problems," and particularly in mathematics classrooms where a dominant culture is said to further exclude girls, there is an exigency to understand how in fact Latina students could experience education as transformative. Critical race and feminist theories further argue for centralizing the experiences of women or girls of color as essential to understanding where change can happen in society because of the role that racism and sexism play in structuring educational experiences. Therefore, this study foregrounds the experiences of young Latinas as they engage in critical mathematics.A critical educational paradigm has been put forth whose purpose is to develop critical literacy in students where they investigate, make apparent and challenge oppressive societal structures. This critical ethnographic research study seeks to gain a more nuanced understanding of how young Latinas experience a social justice mathematics learning environment through the facilitation and research of an after-school, all girls mathematics club. More specifically, data in the form of field notes, videotaped sessions, classroom observations, student work and interviews offers a rich source for analysis of their practices in the learning environment, their perceptions of mathematics, themselves as learners of mathematics and as people who can make changes in their lives, communities and in the world. The construct of critical mathematical agency is employed in attempting to understand how the participants' actions expressed a sense of being able to use mathematics to critique and change their worlds. Analysis revealed they engaged in resistance, research and (re)authoring, as ways of expressing critical mathematical agency. In addition, their insight into critical mathematics education highlights the importance of incorporating critical funds of knowledge, fostering collectivity, and centering the experiences in authentic, community contexts. This understanding will inform arguments for seeking social justice through mathematics education and educational research, particularly for Latina youth.
    • "I Understand Everything You Say, I Just Don’t Speak It": The Role of Morphology in the Comprehension of Spanish by Receptive Heritage Bilinguals

      Beaudrie, Sara; Nicol, Janet; Holmes, Bonnie Christina; Beaudrie, Sara; Nicol, Janet; Carvalho, Ana; Pascual y Cabo, Diego (The University of Arizona., 2017)
      This study contributes to what is known about the nature of unbalanced bilingualism that emerges in language contact situations by examining the morphological knowledge of Spanish receptive heritage bilinguals (RHBs). RHBs were exposed to Spanish in their homes and communities but received formal schooling in English. These bilinguals have been described as being "on the verge of culminating the language shift towards English monolingualism" (Beaudrie, 2009a, p. 86), although despite this they report the ability to understand but not speak their heritage language. While the interpretation and production of inflectional morphology are difficult for more proficient heritage bilinguals (Montrul, 2008, 2009), little is known about the extent to which knowledge of morphology is measurable in HRBs or how it contributes to their ability to comprehend spoken Spanish. To answer these questions, 33 adult Spanish RHBs completed four, aurally-presented on- and off-line experimental tasks designed to assess their underlying grammatical competence, their receptive comprehension skills, and their proficiency without requiring that participants speak, read or write in Spanish. These tasks and the skills they assessed are listed below. 1) A self-paced, aural grammaticality judgment task examined whether RHBs have access to the rules that govern the well-formedness of specific inflectional morphemes, including gender and subject/verb agreement, as well as tense, aspect, and mood morphemes. 2) A morpheme interpretation task assessed whether RHBs interpret the meaning supplied by bound morphemes and distinguish between semantic contrasts. 3) A contextualized listening comprehension task measured the listening comprehension abilities of RHBs. 4) An elicited imitation task measured the proficiency of RHBs. The results of this study show that RHBs do have underlying morphological competence and are able to distinguish between grammatical and ungrammatical morphemes despite their limited language skills in other domains. Additionally, these bilinguals interpret the meaning supplied by bound morphemes, although access to the rules governing both the structure and the semantics of these morphemes decreases in accordance with the order in which they were acquired in childhood. RHBs understand the majority of what they hear when listening to spoken Spanish, and on average their proficiency ranges from low to intermediate levels. An analysis of the linear relationship between the results of the four experimental tasks revealed that the extent to which listening comprehension abilities and proficiency correspond to morphological knowledge in Spanish RHBs is dependent on the degree of access that these bilinguals have to the semantic information provided by functional morphemes. The results of this study show that while the core syntax of Spanish RHBs is intact, semantic knowledge may not have been mapped to certain morphemes during the acquisition process. These results are analyzed in tandem with various hypotheses that have been recently put forth to account for the linguistic outcomes of contact bilingualism, and an argument is made for considering heritage grammars as completely acquired but distinct language varieties.
    • I Won't Live On, So I Create: Mortality Salience and Afterlife Belief Strength's Impact on Intention to Engage in Creation-Oriented Consumption

      Brucks, Merrie L; Greenberg, Jeff; Xu, Huimin; Brucks, Merrie L; Greenberg, Jeff; Erickson, Lance; Nielsen, Jesper (The University of Arizona., 2006)
      Creative behaviors are part of an average consumer's everyday life. For example, amateur people buy various art and craft supplies from stores like Michael's, purchase studio time to make pottery, and collect camera accessories to help demonstrate their originality in photography. Usually the final creative product can be preserved for a long period of time. These creative activities are avidly pursued primarily because they provide consumers with enjoyment and a sense of fulfillment. I am coining the term "creation-oriented consumption" to refer to this phenomenon, which is one specific type of creative consumption.Terror management theory is used to examine why people engage in creation-oriented consumption. I hypothesize that mortality salience boosts the intention to engage in creation-oriented consumption; and under mortality salience, weakened afterlife belief increases the intention for this type of consumption.Three experimental studies are conducted, each adopting a somewhat different perspective. Study 1 gauges intention to engage in creation-oriented consumption against inaction. It finds that mortality salience increases interest in creation-oriented consumption; and that under mortality salience, weakened afterlife belief increases interest in creation-oriented consumption. Study 2 examines durable creation-oriented consumption's appeal relative to other activities, namely, non-creative activities and creative consumption that does not leave durable traces. The proposed effect of mortality salience is observed only when individuals possess a low level of chronic afterlife belief. Unexpectedly, interest in creative consumption is reduced under mortality salience. Consistent with study 1, study 2 finds that under mortality salience, weakened afterlife belief raises interest in creation-oriented consumption. Study 3 replicates the finding of study 2 that mortality salience dampens general interest in creativity. Taken together, these studies suggest that although creation-oriented consumption ameliorates existential anxiety, it is not the most effective one in the short term.Apart from the major hypotheses, this dissertation also investigates some boundary conditions. Two of the three studies find that the question of whether creative consumption leaves a durable trace is of significance.
    • "I Wouldn't Change Anything": The Everyday Realities of Living with Autism from a Parent's Perspective

      Gilmore, Perry; Molina, Rudy Modesto, Jr.; Gilmore, Perry; Ruiz, Richard; Fletcher, Todd (The University of Arizona., 2014)
      Using qualitative methods, this study is about the attitudes and daily practices of parents who genuinely want the best for their children who have been diagnosed with autism. The study examined the everyday realities of living with autism from a parent's perspective. The purpose of this study was to describe the range of specific behaviors, practices, attitudes, and ways of being that families adopt when they engage in the world of autism. Three families were interviewed in these case studies. A content analysis of the interviews identified five thematic clusters that are described and examined in close detail. The five thematic clusters include (1) managing the diagnostic process, (2) child's behavior and educational needs, (3) impact on parent's well-being, (4) impact on the family as a whole, and (5) full integration into mainstream society. These themes were further categorized according to the "challenges" facing the families and the specific "strategies" families used to face these challenges. Parents shared their stories with the researcher with the hopes that their life experiences could be beneficial to other families facing the same challenges as they navigate complex educational, health, and social systems. The research presents a set of recommendations that were embedded in the participants' stories. These recommendations represent advice from the parents in the study to other parents with children diagnosed with autism. Their recommendations are based on what the participants have learned as they raised their own child with autism.
    • I'd Give My Right Kidney to Be Altruistic: The Social Biogeography of Altruism in the United States of America

      Figueredo, Aurelio Jose; Garcia, Rafael Antonio; Figueredo, Aurelio Jose; Jacobs, William Jake; Steklis, Horst Dieter; Davis, Melinda (The University of Arizona., 2017)
      The purpose of this dissertation is to model biosocial determinants of group-directed altruistic behavior – exploring the nomological net around it. To do this a study will be presented to determine existing associations among various biological and social predictors and test a life-history-derived causal cascade using a partially exploratory and partially confirmatory statistical technique called Sequential Canonical Analysis to ultimately predict living-donor, non-directed kidney donations (NDKD). Toward that end, some important methodological considerations first need to be discussed. The first consideration revolves around the level of analysis and how this frames the cascade model and its interpretation. Following a general discussion, an exercise in some of the general principles is provided – investigating the higher-order factor structure of the Big-5 personality constructs across two levels of analysis. The second consideration is the use of unit-weighted factor scores and their appropriateness. Following the theoretical discussion, a demonstration is provided – deriving an estimate of genetic relatedness from a set of heterogeneous data sets. Once the methodological considerations have been discussed, the primary cascade model is presented in two parts: 1) the measurement model – operationalizing the measures incorporated into 2) the structural model – testing the proposed causal cascade using Sequential Canonical Analysis. A discussion follows in which the results are summarized, limitations are articulated, and further research directions are explored.
    • I. A. Richards' new rhetoric: Metaphor and 'Ethos'.

      Enos, Theresa; Brown, Stuart Cameron.; Willard, Thomas; Roen, Duane (The University of Arizona., 1990)
      Initially acknowledged as leading to a revitalized rhetoric, I. A. Richards' contributions now are neglected. Three themes weave through this discussion of Richards' works and their value. First, he should be more thoroughly recognized as a pivotal force in twentieth-century rhetoric who brought rhetoric into modernity and thus set the stage for much of current rhetorical inquiry. Second, his speculations on the meaning of meanings provide the basis for a study of ethos that will pay close attention to the evaluations readers and writers, speakers and listeners, bring to rhetorical situations. Third, his inquiries into metaphor are germinal, initiating the growing perception that metaphor is the constituent of language use and meaning. Because he conjoins a new understanding of metaphor and of ethos, Richards provides the basis of a truly "new" rhetoric, one crucial to what he calls "the world we make for ourselves to live in." Current rhetorical theory, history of metaphor studies, and contemporary accounts of metaphor are discussed in relation to Richards' works.
    • I. Analysis of biological specimens by proton-induced x-ray emission spectroscopy (PIXE). II. Separation and purity of carbon₆₀ and carbon₇₀.

      Lowe, Timothy Paul.; Fernando, Quintus; Pemberton, Jeanne E.; Enemark, John H.; Vemulapalli, G. K.; Rund, John V. (The University of Arizona., 1993)
      Proton induced x-ray emission spectroscopy (PIXE) is a rapid and sensitive analytical technique for the non-destructive simultaneous determination of elemental concentrations above atomic number 11 (sodium) and is the only analytical technique that can determine 20-30 elements nondestructively in a single small sample (≈5 mg) with detection limits of 1- 5 ppm (dry weight). Part I of this dissertation outlines work done on the optimization of instrumental parameters and sample preparation for the analysis of biological tissue. Cultured rabbit renal slices were used as the biological system to demonstrate the use of PIXE analysis. The renal slices were exposed to HgCl₂, CdCl₂, K₂Cr₂0₇, or NaAsO₂ alone or in a mixture. The analysis of biological samples by PIXE provides information on inter-elemental interactions in tissue and body fluids. A computer program for spectrum processing and quantitation, which decomposes overlapped peaks, corrects for thick target matrix effects and calculates results without resorting to the use of standards, is explored. In part II of this dissertation, a convenient method of removing solvent from a benzene extract of graphitic soot containing fullerenes using sublimation, is outlined. Separation of macroscopic quantities of the fullerenes C₆₀ and C₇₀ has been accomplished using a combination of selective precipitation of C₆₀ and chromatography. C₆₀ is selectively crystallized by freezing and thawing a benzene solution of mixed fullerenes, then using the C₇₀ enriched supernatant as starting material in the chromatographic separation of C₆₀ and C₇₀. In the separation scheme, a bed of modified silica sorbent is charged with the fullerene mixture and the fullerenes are eluted using a hexanes/THF mobile phase. The methods of uv-Visible and infrared spectroscopy, as well as high performance liquid chromatography (HPLC) are evaluated for their ability to determine the purity of a C₆₀ or C₇₀ sample.
    • I. Causes of Multiple Diffusing Populations of Fluorescently Labeled Probes in Lipid Membranes II. Evaluation of Phospholipid Membranes Incorporating the Polymerizable Lipid Bis-Denpc (16, 16) and Suitability as Ultra-Stable Platforms for Ion Channel Based Sensors

      Saavedra, S. Scott; Smith, Christopher M.; Aspinwall, Craig A.; Pemberton, Jeanne E.; Denton, Bonner; Brown, Michael F. (The University of Arizona., 2019)
      This dissertation is composed of two major projects, though some capabilities and findings from the first project were applied to the second. Project I focuses on advancements made in the understanding of the chemical interactions of a number of commonly used fluorescently labeled phospholipid probes. These probes are used for a variety of studies, including labeling of cellular or artificial membranes, examining transport and communication between different membranes, and determining membrane fluidity. Understanding the chemical behavior and interactions of these probes in membranes can be key for the proper interpretation of experimental data. Utilizing fluorescent recovery after photobleaching (FRAP), in combination with other spectroscopic techniques, multiple diffusing populations of commonly used probes in various artificial lipid membrane formats were identified, as were the causes for these populations. This allows for a fuller description of the fluidity of lipid membranes. These findings are the focus of Chapters 3 and 4 while the hardware developed that enabled critical measurements is the focus of Chapter 2. Project II focuses on addressing key limitations in developing ion channel (IC) based biosensors utilizing artificial lipid membranes. Among these limitations are the weak mechanical, chemical, and electrical stabilities of artificial lipid bilayers due to the weak noncovalent interactions involved in the membrane. To address these limitations, the polymerizable lipid bis-dienoyl phosphatidylcholine (bis-DenPC(16, 16)) was characterized for its ability to form ultra-stable membranes suitable for IC based sensors using the model IC gramicidin A (gA). Special attention was given to determining the membrane fluidity given the requirement of gA that two subunits must laterally diffuse to converge and dimerize to form a conductive pore. These studies are the focus of Chapters 5 and 6.
    • I. Cyclopropyl anions II. Charge-transfer monomers and polymers

      Brand, Richard Allen, 1947- (The University of Arizona., 1975)
    • I. Development of Rapid Conductance-Based Protocols for Measuring Ion Channel Activity; II. Expression, Characterization, and Purification of the ATP-Sensitive, Inwardly-Rectifying K+ Channel, Kir6.2, and Ion Channel-Coupled Receptors

      Aspinwall, Craig A.; Saavedra, Steve S.; Agasid, Mark Tadashi; Aspinwall, Craig A.; Saavedra, Steve S.; Hruby, Victor J.; Heien, Michael L. (The University of Arizona., 2017)
      Ligand-gated and ligand-modulated ion channel (IC) sensors have received increased attention for their ability to transduce ligand-binding events into a readily measurable electrical signal. Ligand-binding to an IC modulates the ion flux properties of the channel in label-free manner, often with single-molecule sensitivity and selectivity. As a result, ICs are attractive sensing elements in biosensoring platforms, especially for ligands lacking optical (e.g. fluorescent) or electrochemical properties. Despite the growing number of available ligand-gated and ligand-modulated ICs and artificial lipid bilayer platforms for IC reconstitution, significant work remains in defining the analytical performance capabilities of IC sensors. Particularly, few studies have described platforms for making measurements with rapid temporal resolution and high sensitivity. In this work, we describe an artificial lipid bilayer platform which enables rapid measurement of ion channel activity, a key parameter for developing IC sensors suitable for studying biological events, e.g. single cell exocytosis (Chapter 2 and 3). Additionally, we developed expression, purification, and reconstitution protocols for Kir6.2, a model ligand-gated ion channel, for use in sensor development (Chapter 4). The final goal is to reconstitute ion channel-coupled receptors (ICCRs), G protein-coupled receptor-Kir6.2 fusion proteins, into artificial lipid bilayers to detect small molecules and hormones targeting GPCRs. Towards this goal, we characterized the expression and function of two ICCRs, M2-Kir and D2-Kir, in HEK293 cells (Chapter 5).