Now showing items 14826-14845 of 19641

    • The R Chondrite Record of Volatile-Rich Environments in the Early Solar System

      Lauretta, Dante S.; Miller, Kelly E.; Lauretta, Dante S.; Connolly, Harold C., Jr.; Zega, Thomas J.; Pascucci, Ilaria; Downs, Robert T.; Swindle, Timothy D. (The University of Arizona., 2016)
      Chondritic meteorites are undifferentiated fragments of asteroids that contain the oldest solids formed in our Solar System. Their primitive, solar-like chemical compositions indicate that they experienced very little processing following accretion to their parent bodies. As such, they retain the best records of chemical and physical processes active in the protoplanetary disk during planet formation. Chondritic meteorites are depleted relative to the sun in volatile elements such as S and O. In addition to being important components of organic material, these elements exert a strong influence on the behavior of other more refractory species and the composition of planets. Understanding their distribution is therefore of key interest to the scientific community. While the bulk abundance of volatile elements in solid phases present in meteorites is below solar values, some meteorites record volatile-rich gas phases. The Rumuruti (R) chondrites record environments rich in both S and O, making them ideal probes for volatile enhancement in the early Solar System. Disentangling the effects of parent-body processing on pre-accretionary signatures requires unequilibrated meteorite samples. These samples are rare in the R chondrites. Here, I report analyses of unequilibrated clasts in two thin sections from the same meteorite, PRE 95404 (R3.2 to R4). Data include high resolution element maps, EMP chemical analyses from silicate, sulfide, phosphate, and spinel phases, SIMS oxygen isotope ratios of chondrules, and electron diffraction patterns from Cu-bearing phases. Oxygen isotope ratios and chondrule fO2 levels are consistent with type II chondrules in LL chondrites. Chondrule-sized, rounded sulfide nodules are ubiquitous in both thin sections. There are multiple instances of sulfide-silicate relationships that are petrologically similar to compound chondrules, suggesting that sulfide nodules and silicate chondrules formed as coexisting melts. This hypothesis is supported by the presence of phosphate inclusions and Cu-rich lamellae in both sulfide nodules and sulfide assemblages within silicate chondrules. Thermodynamic analyses indicate that sulfide melts reached temperatures up to 1138 °C and fS2 of 2 x 10^(-3) atm. These conditions require total pressures on the order of 1 atm, and a dust- or ice-rich environment. Comparison with current models suggest that either the environmental parameters used to model chondrule formation prior to planetesimal formation should be adjusted to meet this pressure constraint, or R chondrite chondrules may have formed through planetesimal bow shocks or impacts. The pre-accretionary environment recorded by unequilibrated R chondrites was therefore highly sulfidizing, and had fO2 higher than solar composition, but lower than the equilibrated R chondrites.Chalcopyrite is rare in meteorites, but forms terrestrially in hydrothermal sulfide deposits. It was previously reported in the R chondrites. I studied thin sections from PRE 95411 (R3 or R4), PCA 91002 (R3.8 to R5), and NWA 7514 (R6) using Cu X-ray maps and EMP chemical analyses of sulfide phases. I found chalcopyrite in all three samples. TEM electron diffraction data from a representative assemblage in PRE 95411 are consistent with this mineral identification. TEM images and X-ray maps reveal the presence of an oxide vein. A cubanite-like phase was identified in PCA 91002. Electron diffraction patterns are consistent with isocubanite. Cu-rich lamellae in the unequilibrated clasts of PRE 95404 are the presumed precursor materials for chalcopyrite and isocubanite. Diffraction patterns from these precursor phases index to bornite. I hypothesize that bornite formed during melt crystallization prior to accretion. Hydrothermal alteration on the parent body by an Fe-rich aqueous phase between 200 and 300°C resulted in the formation of isocubanite and chalcopyrite. In most instances, isocubanite may have transformed to chalcopyrite and pyrrhotite at temperatures below 210°C. This environment was both oxidizing and sulfidizing, suggesting that the R chondrites record an extended history of volatile-rich interaction. These results indicate that hydrothermal alteration of sulfides on the R chondrite parent body was pervasive and occurred even in low petrologic types. This high temperature aqueous activity is distinct from both the low temperature aqueous alteration of the carbonaceous chondrites and the high temperature, anhydrous alteration of the ordinary chondrites.
    • Race & Class: An Intergenerational Study of Privileged African Americans Educated in Predominantly White and Integrated Suburban Schools

      Griego-Jones, Toni; Davis Welch, JerMara Camille (The University of Arizona., 2015)
      This dissertation sought to better understand the K-12 school experiences of middle and upper income Blacks educated in predominantly White and integrated suburban school systems. Through the narratives of six (6) participants—four females and two males (split evenly between Generations Y and Z)—the study contributes toward knowledge on African American within-group differences and perspectives on K-12 school experiences. The theoretical frames of social location and trust were used to help guide this investigation. Through social location, I sought to understand the interconnectedness of one's race, class, and gender and how these locations impact school experiences. Through the theoretical frame of trust, I sought to understand "overall" participant confidence in the educational processes (academic and social) they underwent. While findings from this dissertation matched some of what is already well-documented on the K-12 school experiences of Black American students in general, by focusing on within-group differences relevant to class and generational grouping, key variances in experiences (not often reported) were revealed. For example, as the study was intergenerational in scope, there was a clear generational divide among study participants in terms of their views relating to how race impacted their K-12 school experiences. Despite the fact that most felt that their schools were not sensitive to their needs as African Americans, race seemed to be less of a concern with Gen Z'ers than with Gen Y'ers. More specifically, while participants from Generation Y were explicit in stating that race had an impact on their school experiences, Generation Z was hesitant to say that race influenced their experiences. Interestingly, as all participants dealt with racial stereotyping, the biggest perpetrators of such stereotypes were peers and not educators. The influence of socioeconomic class on school experiences was also significant as most participants felt that their economic status influenced their cross-cultural interactions. In addition, while the social location of gender was not heavily emphasized in this dissertation, there were variations in perspectives stratified across gender lines. Taken together, a major conclusion was that one's social location (inclusive of generational grouping) cannot be ignored when taking into account the academic experiences of African American students as a whole. Finally, this dissertation highlighted the overall confidence each participant had in the educational process they experienced (academically and socially). Although all encountered some tough circumstances directly related to their social location, everyone felt positive overall about their school experiences—perceiving the academic training they received and inter-ethnic social interactions, as an asset.
    • Race and the Matrix Movie Trilogy

      Sanchez, Tani Dianca; Babcock, Barbara A.; Bernardi, Daniel; LeSeur, Geta; Smith, Howard; Smith-Shomade, Beretta; Whaley, Deborah (The University of Arizona., 2006)
      Using a close textual and contextual analysis, I trace themes of gender and race in the Matrix trilogy, arguing for the presence of a parallel, embedded filmic narrative, one that neatly aligns with African-American critical traditions affirming subjugated ideologies, knowledges, communities and forms. Decoding the films through the lenses of race, womanist, film studies and cultural studies theories, I explore this signified, covert storyline through phenotypes, casting choices, plot twists, and extra filmic events. In this dissertation project, I argue that their preponderance, consistency, and coherence are evidence of deliberate commentary. I further claim that that the trilogy can be reasonably understood as a historically motivated critique of Whiteness and White supremacy, offering references to American slavery and ideologies, as well as to cross-racial ideological domination and collective, coalitional and revolutionary change. Since long standing racial and gender understandings (along with their attendant domination and oppression) persist, examining popular films with transformed constructions is useful in supporting frameworks for conceptual change.

      Smith, Mae; WILSON, LLOYD KENTON.; Johnson, Bob; Organist, James (The University of Arizona., 1984)
      This study investigated differences among racial groups and between sex groups on psychometric test performances, demographic data, and vocational potential ratings of an adult rehabilitation client sample. Also, the psychometric and demographic variables were included in discriminant function equations to predict the vocational potential ratings of the white, Hispanic, and black groups and of the total sample. The sample in this study was composed of 99 adult rehabilitation clients who completed comprehensive vocational evaluations between January, 1980, and July, 1983. Each case included complete psychometric and demographic data. Also, a vocational potential rating based on this data, other aptitude and ability testing, work sample performances, behavior observations, and other information obtained by the vocational evaluator was reported for each case. Analysis of variance procedures found no significant differences between the male group and the female group of the total sample on the psychometric and demographic variables, or on the cumulative vocational potential rating. Significant differences were found among the racial groups on mean performance of reading comprehension and arithmetic computation, and on years of education attained. Tukey HSD procedures specified that these differences exist between the white group and the Hispanic group on reading comprehension, between the white group and the black group on arithmetic computation, and between the white and black groups and the hispanic group on years of educaton attained. Also, no significant differences were demonstrated among the racial groups on general mental ability, age, or cumulative vocational potential ratings. Discriminant function analysis procedures applied the psychometric and demographic variables to the prediction of vocational potential ratings of the racial groups and of the total sample. Observation of the resulting prediction equations indicated that some external bias may exist in the use of these equations for predicting vocational potential in white, Hispanic, and black groups. Also, no single predictor variable was the primarily selected variable in all of the discriminant function equations of vocational potential ratings in the total sample. Overall, the predictive power of the discriminant function equations was not sufficient to recommend their use in clinical practice.
    • Race relations in schools: The effects of competition and hierarchy on education, sports participation, and standardized test scores

      Shockey, James S.; Goldsmith, Pat Antonio (The University of Arizona., 1999)
      I investigate the influence of race upon high school student's approaches to education, sports participation, and high school test scores. The theoretical perspective employed suggest that the effect of race upon these items will vary across schools. To explain this school level variation, I employ two theories of race relations: competition theory and the cultural division of labor perspective. Using the National Longitudinal and Educational Study of 1988 (NELS: 88) and multilevel model statistical procedures, support for both theories is found. I conclude that race relations in schools impact student's cultural activities and test scores.
    • Race to the Top-Early Learning Challenge: An Analysis of Impact on IDEIA, Part C Early Intervention Programs

      Umbreit, John; Bohjanen, Sharon Lynn; Bricker, Diane; Antia, Shirin; Levine-Donnerstein, Deborah L.; Umbreit, John (The University of Arizona., 2016)
      Infants and toddlers who live in poverty are more likely to experience developmental delays or disabilities and less likely to access early intervention (EI) services. The federal initiative Race to the Top-Early Learning Challenge (RTT-ELC) was designed to increase access to high quality early learning programs for children at risk for developmental delays due to poverty or disability. Although IDEA, Part C programs were not specifically targeted by this initiative, policies associated with RTT-ELC may have an indirect impact on state EI programs. The purpose of this study was to examine the effects of RTT-ELC on Part C programs by comparing states that received federal grants to states that did not. This study used a social justice framework to identify variables that inform equitable access to high quality Part C programs. Data were extracted from Part C state profiles and compared across states. Awarded states were more likely to increase enrollment of infants and toddlers in Part C Programs and were more likely to use broad eligibility criteria. These findings indicated that although differences were small they could become more pronounced over time. The need for policy change in Part C programs and federal early learning initiatives to directly target infants, toddlers and families in poverty are highlighted through the results of this study.

      BOSWELL, TERRY E.; Fligstein, Neil (The University of Arizona., 1984)
      A theoretical framework is developed for incorporating class conflict dynamics into accumulation theories of labor market segmentation by analyzing the transaction costs of conflict under varying conditions of economic structure and power resources. The theory has the "bottom up" perspective developed in the "new social history." Skill is treated as a status for which workers struggle and internal labor market hierarchies are considered products of the conflicting strategies between capital and labor. Split-labor market theory is also discussed as a method for explaining why workers discriminate. This theory is amended to distinguish between market and class interests of workers, and to take into account the self-perpetuating economic effects of racist discourse. My historical analysis of the metal-mining industry emphasizes the formation of ethnically stratified segments of the labor market in which Chinese and Mexican workers were denied access to the craft-internal labor market for skilled workers. Competition over mining claims under the threat of takeover by mining companies created ethnic antagonism between Chinese and white independent petty-commodity miners. Discrimination by the white independent miners crowded the Chinese into the labor market, which reduced Chinese wages, and induced conflict between white and Chinese wage workers in the company-mines. Ethnic antagonism in combination with intense class struggle produced a segregated labor market between Mexican miners and Anglo supervisors during the initial proletarianization of the mines. Mexican miners were later displaced by Cornish miners who developed a segregated craft-internal labor market. Analysis of the labor process shows that mechanization initially facilitated the struggle by Cornish miners for a skilled status, contrary to homogenization expectations. Mexican miners were relegated to unskilled manual positions.
    • Race, gender, and the labor market: Black and white women's employment

      England, Paula S.; Reid, Lori Lynn (The University of Arizona., 1997)
      Historically, black women's employment levels have exceeded those for white women. However, looking only at young cohorts of women, the employment levels of black and white women were equal by 1969, and by 1991 white women's employment greatly exceeded black women's employment. If this continues to be true for successive new cohorts, it suggests that, overall, white women will soon be working at significantly higher rates than black women for the first time in history. Identifying the determinants of women's employment today becomes an important issue not only for explaining the factors that affect labor market outcomes but also for explaining the prospects for black and white women in the labor market. Utilizing the National Longitudinal Survey of Youth, I use event history methods to analyze the determinants of black and white women's employment in the contemporary U.S., and explain any race gaps in employment that emerge. My findings suggest that a race gap in the hazard of part-time employment exists among women in which the rate of part-time employment is lower for black than white women. This gap is explained by race differences in human capital and past welfare receipt. A race gap in the hazard of full-time employment exists among unmarried women in which the rate of full-time employment is lower for black than white women. This gap is explained by race differences in age, human capital, and past welfare receipt. I find that opportunities and constraints provided by the local economic environment, human capital, family structure, and past welfare receipt are an important influence on black and white women's employment.
    • Race-crossings at the crossroads of African American travel in the Caribbean

      Kolodny, Annette; Alston, Vermonja Romona (The University of Arizona., 2004)
      Traversing geographical borders frequently allows people the illusion of crossing social, political, and economic boundaries. For African-Americans of the early twentieth century, crossing physical borders offered the promise of freedom from racial segregation and discrimination in all aspects of social, political, and cultural life. Haiti became a site for African-American imaginings of a free and just society beyond the problem of the color line. From the 1920's through the 1980's, African-American travel writing was strategically deployed in efforts to transform a U.S. society characterized by Jim Crow segregation. In the process, Haiti and the rest of the Caribbean were romanticized as spaces of racial equality and political freedom. This project examines the ways in which the Caribbean has been packaged by and for African-Americans, of both U.S. and Caribbean ancestry, as a place to re-engage with romanticized African origins. In the selling of the Caribbean, cultural/heritage tourism, romance/sex tourism and ecotourism all trade on the same metaphors of loss and redemption of the innocence, equality, and purity found in a state of nature. Through analyses of standard commercial tourism advertising alongside of travel writing, I argue that with the growth of the black middle-class in the late 1980's crossings to the Caribbean have become romantic engagements with an idealized pastoral past believed lost in the transition to middle-class prosperity in the United States. African-American travel writers, writing about the Caribbean, tend to create a monolithic community of cultural belonging despite differences of geography and class, and gender hierarchies. Thus, African-American travelers' tales constitute narratives at the crossroads of celebrations of their economic progress in the United States and nostalgia for a racial community believed lost on the road to suburban prosperity. For them, the Caribbean stands in as the geographical metaphor for that idealized lost community.

      Marlatt, Robert B. (Robert Bruce), 1920- (The University of Arizona., 1952)
    • Rachel Calof's text(s): Family, collaboration, translation, 'Americanization'

      Temple, Judy Nolte; Peleg, Kristine (The University of Arizona., 2003)
      Rachel Calof's Story. Jewish Homesteader on the Northern Plains (Ed. J. Sanford Rikoon, Indiana University Press, 1995) is a first-person memoir of homesteading in North Dakota from 1894-1917, based on Rachel Calof's Yiddish manuscript. I traced this text from inception to publication, especially the translation and editing process, comparing a new translation of the Yiddish manuscript with the English publication. Since the differences proved significant, my research investigated issues of oral history transmission and collaboration. In light of new scholarship in autobiography theory, particularly Paul Eakin's "proximate collaborative autobiography," I consider Rachel Calof's Story a hybrid text, integrating both oral histories and written texts to portray a more complete picture of homestead life. Rachel's son, Jacob, compiled the English version for publication, bringing a comprehensive knowledge of her life, and yet complicating objectivity because he was, indeed, her son. Recent scholarship in women's and western studies focuses on situational context; investigation of diversity supplements an increasingly multi-faceted picture. Contemporary scholarship in immigrant literature emphasizes ambivalence rather than assimilation and changed how I considered the Calof story. I apply the Personal Narratives Group's conceptualization of context, narrator-interpreter relations and multiple connotations of "truths." The oral nature of the Yiddish language is also considered as influencing the translation. I analyze specific themes at length: Rachel Calof's physical environment of home, prairie and transitional spaces; the rhetoric of frontier settlement; home in physical and religious terms; and finally, Americanization as an editorial emphasis which reduced ethnic and religious distinctions. Other multi-authored works, including those of Anne Frank, Laura Ingalls Wilder and Black Elk, reveal parallel collaborative tensions. Neither generational nor gender differences entirely explain alterations families and ethnographers make in editing transmitted works. Barbara Myerhoff's concept of the "third voice" particularly influenced my understanding the dialogic nature of manuscripts and oral histories. Finally, I question whether publishers and audiences are complicit in the demand for success stories even at the expense of stifling an author's voice. The English publication of Rachel Calof's Story was polished and unaccented; the original Yiddish manuscript was a stream of consciousness that might not have been published.
    • Racial and Ethnic Disparities Among Minority Geriatric Trauma Patients in the United States: An Analysis of Data From a National Sample Using the Trauma Quality Improvement Program Database

      Gerald, Joe K.; Rosales, Cecilia; Saljuqi, Abdul Tawab Kawa; Gerald, Joe; Joseph, Bellal; Fain, Mindy; Hsu, Paul (The University of Arizona., 2020)
      For this dissertation, I completed three manuscripts with the common overall aim of assessing health disparities among geriatric trauma patients in the U.S. The first manuscript reports on a structured narrative review of the literature comprised of three approaches that ensure comprehensive and targeted research: a scoping review, an exploratory search, and a citation review. The second manuscript is a descriptive analysis of one-year (2016) of data from the American College of Surgeon’s Trauma Quality Improvement Program (ACS-TQIP) with a focus on older adults aged 65 and older who have had an injury. The population was stratified into four groups: Non-Hispanic Whites (NHWs), African Americans, Hispanics, and Other races. For each group, I conducted a simple univariate tabulation for key demographic characteristics and injury-related variables. I also assessed comorbidities, insurance type, and regional differences. Finally, in manuscript three, I performed a one-year analysis of the ACS-TQIP dataset and included all adult trauma patients aged 65 and older who were admitted in 2016. My primary aim was to understand health disparities regarding in-hospital health measures, such as in-hospital mortality, length of stay (LOS), and in-hospital complications. I conducted multivariable regression analysis controlling for age, gender, injury severity, comorbidities, insurance status, calendar year, and type of trauma center. I argue that racial/ethnic disparity exists for GTPs in terms of in-hospital mortality, in-hospital complications, and LOS. Type of injury, severity of injury, and age group are critical predictors of different health outcomes among minority GTPs. Minimizing disparities in GTPs care is crucial to reducing morbidity and mortality. More focused primary research is needed to expand our knowledge of racial/ethnic disparities among GTPs. It is critical that future research stratify each minority group by differences in injury type, injury severity, and age group.
    • Racial Differences in Time to Withdrawal of Care after Intracerebral Hemorrhage

      Gallek, Matthew J.; Shaw, Kristen Marie; Gallek, Matthew J.; Gallek, Matthew J.; Nakagawa, Kazuma; Sheppard, Kate G.; Ritter, Leslie (The University of Arizona., 2014)
      Intro/Aims: Differences in end-of-life decision-making among minorities have been well described. However, among Native Hawaiian and Other Pacific Islanders (NHOPIs), this has not been well studied. Aim 1: Determine if differences in time to withdrawal of life support (WOLS) exist between NHOPIs and non-Hispanic whites (NHWs). Aim 2: If differences in time to WOLS between races are found, examine factors that may contribute to these differences. Methods: A retrospective study was conducted on patients admitted to a primary stroke center in Honolulu with diagnosis of spontaneous intracerebral hemorrhage (ICH). Medical records were reviewed for occurrence of WOLS and time of WOLS. Unadjusted and multivariable logistic regression models were performed to determine associations between race and WOLS. Kaplan Meier analysis and Cox regression were performed to estimate survival time to WOLS and to compare these results between racial groups. Results: 396 patients with diagnosis of spontaneous ICH were studied. Mean time to WOLS after ICH was found to be similar between NHWs and NHOPIs (p = .925). Prevalence of WOLS was significantly lower in NHOPIs in univariate analysis (odds ratio [OR] 0.35, 95% confidence interval [CI] 0.15, 0.80) and Kaplan Meier analysis predicted a significant difference in WOLS between NHOPI and NHWs within 30 days of ICH (p =<. 01). However, in multivariate analysis, race was no longer significant when adjusted for age (OR 0.59, 95% CI 0.25, 1.43) and when fully adjusted (OR 0.68, 95% CI 0.20, 2.39). NHOPIs were significantly younger at the time of ICH when compared to NHWs (p =<.001) although ICH severity and presentation such as initial Glasgow Coma Scale, presence of intraventricular hemorrhage and ICH volume were similar (p = .241; p = .604; p = .901, respectively). Conclusions: No difference in mean time to WOLS was noted between NHOPIs and NHW. However, secondary analysis showed WOLS was less prevalent after ICH in the NHOPI population compared to NHWs, although the significance of this finding was attenuated by age. NHOPIs in this population likely had a lower incidence of WOLS due to the fact that they presented with ICH at a significantly younger age, although small sample size also may have resulted in difficulty detecting variances between races.
    • Racial Identification, Knowledge, and the Politics of Everyday Life in an Arizona Science Classroom: A Linguistic Ethnography

      Wyman, Leisy T.; O'Connor, Brendan Harold; Gilmore, Perry; González, Norma; Mendoza-Denton, Norma; Wyman, Leisy T. (The University of Arizona., 2012)
      This dissertation is a linguistic ethnography of a high school Astronomy/Oceanography classroom in southern Arizona, where an exceptionally promising, novice, white science teacher and mostly Mexican-American students confronted issues of identity and difference through interactions both related and unrelated to science learning. Through close analysis of video-recorded, naturally-occurring interaction and rich ethnographic description, the study documents how a teacher and students accomplished everyday classroom life, built caring relationships, and pursued scientific inquiry at a time and in a place where nationally- and locally-circulating discourses about immigration and race infused even routine interactions with tension and uncertainty. In their talk, students appropriated elements of racializing discourses, but also used language creatively to "speak back" to commonsense notions about Mexicanness. Careful examination of science-related interactions reveals the participants' negotiation of multiple, intersecting forms of citizenship (i.e., cultural and scientific citizenship) in the classroom, through multidirectional processes of language socialization in which students and the teacher regularly exchanged expert and novice roles. This study offers insight into the continuing relevance of racial, cultural, and linguistic identity to students' experiences of schooling, and sheds new light on classroom discourse, teacher-student relationships, and dimensions of citizenship in science learning, with important implications for teacher preparation and practice.
    • Racialized Cultural Capital and Inequality: A Comparative Study of Blackness in Brazil's Tourism Market

      Zavisca, Jane; Hedegard, Danielle A.; Breiger, Ronald; Cornell, Stephen; Zavisca, Jane (The University of Arizona., 2011)
      In my dissertation, I argue that blackness is an accumulable cultural resource that perpetuates racial and class inequality. The overarching question I ask is what determines who benefits from blackness, black bodies or dominant resources? To answer this question, I first develop a framework that integrates cultural capital theory with two streams of research within the sociology of race - `racialization' and `race as a resource.' Next, I demonstrate my argument and address secondary theoretical goals - in globalization and race in Brazil, with an empirical study in the context of cultural tourism.I examine how individuals transform capoeira into a racialized cultural resource through connections to symbols of blackness and the meanings these symbols provoke, within the tourism market in Salvador, Brazil. Capoeira is a globally popular Brazilian martial art often linked to blackness, which brings American and European tourists together with Brazilian practitioners in an interactive setting. Cosmopolitan consumers now interpret cultural symbols of racial difference, including blackness, as valuable, and tourism exemplifies the growing value of racial otherness. Salvador, Brazil is a central site in the framing of blackness for cosmopolitan consumers. Tourist settings allow me to examine how individuals acquire embodied cultural capital through experience with cultural others. Scholars connect Brazil's extreme social inequality to race and class, and they reveal a profound ambiguity over racialized cultural heritage in Brazil. This creates a context where Brazilians of diverse racial and class backgrounds can benefit from racialized culture.How do racial meanings emerge as tourists and Brazilians interact, how does blackness becomes valuable as valuable a social, cultural, or economic resource for producers and consumers, and which actors benefit from this racialized cultural capital? I answer these questions through comparative participant observation and interviews at two capoeira studios. Long-term participant observation allows me to focus on the embodiment of experiences and the how of cultural valorization. Comparative ethnography best provides insight into how individuals, groups, and organizations put cultural capital to practical use to control and limit resources, allowing for two layers of analysis - one, of interactional meaning making and cultural enactment and the other, a cross-group comparison of these micro-level processes.
    • Radar Analysis and Theoretical Modeling of the Presence and Preservation of Ice on Mars

      Byrne, Shane; Bramson, Ali M.; McEwen, Alfred S.; Richardson, Randall M.; Pelletier, Jon D.; Carter, Lynn M. (The University of Arizona., 2018)
      The distribution and nature of water ice on Mars has important implications for understanding the Martian climate system, as well as evaluating the resources available for future human explorers and the astrobiological potential of our solar system. This dissertation presents a multi-faceted study of ice on Mars, combining spacecraft remote sensing datasets from imaging and radar systems with theoretical models of ice stability. In Chapter 1, I summarize the state of knowledge of ice on Mars and its relation to the planet’s climate. In Chapter 2, I present the discovery of an ice sheet in the mid-latitude region of Arcadia Planitia and constrain its properties using remote sensing observations from the Mars Reconnaissance Orbiter. In Chapter 3, I model the thermal stability and retreat from ice sheets in the mid-latitudes to understand their evolution and continued preservation to the present day. Ice in the mid-latitudes exchanges with polar ice over geologic time so to understand the other half of the Martian system, I investigate the stability of polar deposits of ice. In Chapter 4, I quantify the role of ice sublimation in the migration of troughs in the polar caps. Chapter 5 presents the conclusions of this dissertation work and puts the results in the context of outstanding questions in Mars’ climate and ice-cycle evolution.
    • Radial Growth Relationships in Utah Juniper (Juniperus Osteosperma) and Pinyon Pine (Pinus Edulis)

      Klemmedson, James O.; Despain, Del Westover.; Stokes, Marvin A.; Zwolinski, Malcolm J.; Post, Donald F.; Hendricks, David M. (The University of Arizona., 1989)
      The assumption that each latewood ring in trees represents one year of growth was tested for Utah juniper (Juniperus osteosperma) and pinyon pine (Pinus edulis). Ring characteristics and growth rates were evaluated for 72 years of growth following scars of consistent date on all trees sampled. Errors in age and growth rate estimates based on ring counts were evaluated. Potential variation among observers was accounted for. Average error in ring counts was lowest when rings were counted on the fastest-growing portions of each cross-section. Errors for more than 40% of the junipers exceeded 10 percent with about half of the trees with more rings and half with less rings than actual years. Pinyons rarely had more rings than years and only 5% of the trees were missing more than 10% of the 72 annual rings. Percentage errors in growth rate estimates based on ring counts were similar to ring count errors for both species. Assigning junipers to age classes based on ring counts also can lead to error in assumed ages of trees. Assuming that ring count error for each tree for the 72 year period studied approximates potential error over the life of each tree, more than half of junipers older than 250 years would be assigned to the wrong age class when using 50 year age classes. Number of rings in junipers was highly correlated with growth rate. Competition from surrounding trees explained as much as 53% and 40% of the variation in growth rates of junipers and pinyons respectively. Relating growth rates and ring counts to ordinations of stand, site and soil characteristics indicated that trees with relatively fast growth rates or trees with the most rings tended to occur on gentle, north to northeast aspects with relatively better- developed soils. However, stand competition often had an overriding influence on growth. Presence of Koelaria pyramidata in the understory was generally an indicator of relatively favorable growing conditions for junipers. Results suggest the need for more caution in the use of ring counts for estimating ages or growth rates of Utah junipers and pinyons than has generally been used in the past, especially when drawing conclusions about specific individuals.
    • Radiation And Dynamics In Titan's Atmosphere: Investigations Of Titan's Present And Past Climate

      Russell, Joellen L.; Lunine, Jonathan I.; Lora, Juan Manuel; Russell, Joellen L.; Lunine, Jonathan I.; Griffith, Caitlin A.; Hubbard, William B.; Showman, Adam P. (The University of Arizona., 2014)
      This dissertation explores the coupling between radiative and three-dimensional dynamical processes in the atmosphere of Titan, and their impact on the seasonal climate and recent paleoclimate. First, a simple calculation is used to demonstrate the atmospheric attenuation on the distribution of insolation. The maximum diurnal-mean surface insolation does not reach the polar regions in summertime, and this impacts both surface temperatures and their destabilizing effect on the atmosphere. Second, a detailed two-stream, fully non-gray radiative transfer model, written specifically for Titan but with high flexibility, is used to calculate radiative fluxes and the associated heating rates. This model reproduces Titan's temperature structure from the surface through the stratopause, over nearly six decades of pressure. Additionally, a physics parameterizations package is developed for Titan, in part based on similar methods from Earth atmospheric models, for use in a Titan general circulation model (GCM). Simulations with this model, including Titan's methane cycle, reproduce two important observational constraints---Titan's temperature profile and atmospheric superrotation---that have proven difficult to satisfy simultaneously for previous models. Simulations with the observed distribution of seas are used to examine the resulting distribution of cloud activity, atmospheric humidity, and temperatures, and show that these are consistent with dry mid- and low-latitudes, while the observed polar temperatures are reproduced as a consequence of evaporative cooling. Analysis of the surface energy budget shows that turbulent fluxes react to the surface insolation, confirming the importance of its distribution. Finally, the GCM is used to simulate Titan's climate during snapshots over the past 42 kyr that capture the amplitude range of variations in eccentricity and longitude of perihelion. The results show that the atmosphere is largely insensitive to orbital forcing, and that it invariably transports methane poleward, suggesting Titan's low-latitudes have been deserts for at least hundreds of thousands of years. In detail, seasonal asymmetries do affect the distribution of methane, moving methane to the pole with the weaker summer, though orbital variations do not imply a long-period asymmetry. If the timescale for the atmosphere to transport the surface liquid reservoir is sufficiently short, this explains the observed north-south dichotomy of lakes and seas.
    • Radiation and Immunity in the Context of Cytomegalovirus and Aging

      Nikolich-Zugich, Janko; Pugh, Jason L.; Nikolich-Zugich, Janko; Weinert, Ted; Limesand, Kirsten; Bosco, Giovanni (The University of Arizona., 2013)
      The impact of ionizing radiation exposure on the immune system is dramatic and potentially lethal. The mechanism behind the radiosensitivity of immune subsets has been the concern of researchers for decades, while the long-term effects of radiation exposure in youth have been scarcely explored. The life-long impact of very prevalent latent human viruses, such as Cytomegalovirus (CMV), have recently been brought to the forefront of aging research. However, most short and long-term studies of radiation on the immune system have been performed with animals devoid of latent viruses. Here we describe an innate cause for immune subset radiosensitivity differences, and introduce a post-exposure intervention. We also describe the effects of latent CMV on acute immune sensitivity. Further, we discover that the long-term impact of radiation exposure on the immune system is dependent on whether or not latent CMV was present at the time of exposure. These findings intersect with the research fields of DNA repair, radiobiology, virology, aging, basic immunity, and stand to inform future radiation policy and research.