Matching Items (479)
Description
Once perceived as an unimportant occurrence in living organisms, cell degeneration was reconfigured as an important biological phenomenon in development, aging, health, and diseases in the twentieth century. This dissertation tells a twentieth-century history of scientific investigations on cell degeneration, including cell death and aging. By describing four central developments in cell degeneration research with the four major chapters, I trace the emergence of the degenerating cell as a scientific object, describe the generations of a variety of concepts, interpretations and usages associated with cell death and aging, and analyze the transforming influences of the rising cell degeneration research. Particularly, the four chapters show how the changing scientific practices about cellular life in embryology, cell culture, aging research, and molecular biology of Caenorhabditis elegans shaped the interpretations about cell degeneration in the twentieth-century as life-shaping, limit-setting, complex, yet regulated. These events created and consolidated important concepts in life sciences such as programmed cell death, the Hayflick limit, apoptosis, and death genes. These cases also transformed the material and epistemic practices about the end of cellular life subsequently and led to the formations of new research communities. The four cases together show the ways cell degeneration became a shared subject between molecular cell biology, developmental biology, gerontology, oncology, and pathology of degenerative diseases. These practices and perspectives created a special kind of interconnectivity between different fields and led to a level of interdisciplinarity within cell degeneration research by the early 1990s.
ContributorsJiang, Lijing (Author) / Maienschein, Jane (Thesis advisor) / Laubichler, Manfred (Thesis advisor) / Hurlbut, James (Committee member) / Creath, Richard (Committee member) / White, Michael (Committee member) / Arizona State University (Publisher)
Created2013
Description
This dissertation used an evolutionary approach to examine the antecedents and outcomes to early pubertal development in girls in four major ethnic groups (i.e., European American, African American, Hispanic American, and Asian American). In the first study, logistic regressions were conducted to investigate the links between socioeconomic status (SES), parenting behaviors, and father absence to pubertal development across and within ethnic groups. SES and father absence predicted earlier pubertal development among European, African, and Hispanic Americans but not for Asian Americans. In the second study, growth curves were estimated for sexual outcomes across ethnic groups. Early developing European and African American girls had higher levels of sexual risk and pregnancy into adulthood. Puberty did not predict outcomes for Hispanic and Asian American girls. Overall, the findings from both studies revealed the importance of investigating childhood environmental contexts, puberty, and sexual health outcomes using an evolutionary perspective.
ContributorsBecnel, Jennifer (Author) / Simpkins, Sandra (Thesis advisor) / Christopher, Scott (Thesis advisor) / Dumka, Larry (Committee member) / Updegraph, Kim (Committee member) / Arizona State University (Publisher)
Created2013
Description
Recent reports have indicated that there are both mental health and educational disparities between Latino youth and their European American counterparts. Specifically, Latin youth are at a heightened risk for negative mental health outcomes in comparison to their non-Latino youth (e.g., Eaton et al., 2008). Further, 16.7% of Latino adolescents dropped out of high school compared to 5.3% of European American youth over the past several decades (1960-2011; U.S. Department of Education, 2013). Mexican American (M.A. youth in particular, have the lowest educational attainment among all Latino ethnic groups in the U.S. (U.S. Census Bureau, 2010). While these mental health and educational disparities have often been attributed to discrimination experiences that Latino youth encounter, there is also consistent empirical evidence linking discrimination with these maladjustment problems. These studies confirmed that discrimination directly related to depressive symptoms (e.g., Umana-Taylor et al., 2007), externalizing behaviors (Berkel et al., 2010), self-esteem (e.g., Zeiders et al., 2013), and academic outcomes (e.g., Umana-Taylor et al., 2012). Few studies to date have examined the underlying mechanisms (i.e., moderation and mediation) that help us to better understand resiliency paths for those Latino youth that display positive adjustment outcomes despite being faced with similar discrimination encounters that their maladjusted peers face. Therefore, the following two studies examined various mechanisms in which discrimination related to adjustment to better understand potential risk and resiliency processes in hopes of informing intervention research. Paper 1 explored cultural influences on the association between discrimination, active coping, and mental health outcomes in M.A. youth. Paper 2 examined how trajectories of discrimination across 5th, 7th, and 10th grades related to cultural values, externalizing behaviors, and academic outcomes in M.A. youth. Taken together, these studies provide a culturally informed overview of adjustment processes in M.A. adolescents who face discrimination in addition to identifying critical directions for future research in efforts to gaining a more contextualized and comprehensive understanding of the dynamic processes involved in discrimination and adjustment in M.A. youth.
ContributorsO'Donnell, Megan (Author) / Roosa, Mark W. (Thesis advisor) / Dumka, Larry (Committee member) / Gonzales, Nancy (Committee member) / Barrera, Manuel (Committee member) / Arizona State University (Publisher)
Created2014
Description
Analysis of social networks has the potential to provide insights into wide range of applications. As datasets continue to grow, a key challenge is the lack of a widely applicable algorithmic framework for detection of statistically anomalous networks and network properties. Unlike traditional signal processing, where models of truth or empirical verification and background data exist and are often well defined, these features are commonly lacking in social and other networks. Here, a novel algorithmic framework for statistical signal processing for graphs is presented. The framework is based on the analysis of spectral properties of the residuals matrix. The framework is applied to the detection of innovation patterns in publication networks, leveraging well-studied empirical knowledge from the history of science. Both the framework itself and the application constitute novel contributions, while advancing algorithmic and mathematical techniques for graph-based data and understanding of the patterns of emergence of novel scientific research. Results indicate the efficacy of the approach and highlight a number of fruitful future directions.
ContributorsBliss, Nadya Travinin (Author) / Laubichler, Manfred (Thesis advisor) / Castillo-Chavez, Carlos (Thesis advisor) / Papandreou-Suppappola, Antonia (Committee member) / Arizona State University (Publisher)
Created2015
Description
Early Childhood Education (ECE) classroom quality has been gaining increased attention from researchers and policy makers, as the link between high quality early learning experiences and future success has become clear. The impact of ECE may be particularly important for low-income, ethnic minority youth, who may need additional support to reach the academic level of their higher-income, Caucasian peers. However, the definition of ECE quality does not currently include indicators of classroom practices and center-wide policies that intentionally address issues of culture, race, and ethnicity, topics that may be particularly relevant for the most academically at-risk children. Anti-bias education (ABE) provides a strong theoretical and practical framework for understanding how to incorporate such themes into classroom practice and policy, as well as how to teach students to actively counteract bias and discrimination. However, there is currently no mechanism for researchers to utilize this framework, because there is no measure that can reliably evaluate the level of quality of ABE practices. Therefore, the present study sought to incorporate anti-bias education principles into the conceptualization of classroom quality through measurement development. The measure was developed based on the integration of the original ABE theory with interviews and observations in five ECE programs, which were nominated for their intentional practices regarding issues of culture, race, and ethnicity in the classroom. The five centers ranged in the ethnic composition and average income of their population. The resulting measure contains five domains, with a number of items within each domain. Two of the domains (Toys & Materials, Visual/Aesthetic Environment) contain observational rubrics for assessment, whereas the other three (Organizational Climate, Activities, Interactions) include self-report scales in addition to the rubrics. Future research is needed to pilot the measure and establish validity and reliability across contexts and observation times.
ContributorsGaias, Larissa Michelle (Author) / Dumka, Larry (Thesis advisor) / Shivers, Eva M (Committee member) / Simpkins, Sandra (Committee member) / Arizona State University (Publisher)
Created2015
Description
Leo Kanner first described autism in his 1943 article in Nervous Child titled "Autistic Disturbances of Affective Contact". Throughout, he describes the eleven children with autism in exacting detail. In the closing paragraphs, the parents of autistic children are described as emotionally cold. Yet, he concludes that the condition as he described it was innate. Since its publication, his observations about parents have been a source of controversy surrounding the original definition of autism.
Thus far, histories about autism have pointed to descriptions of parents of autistic children with the claim that Kanner abstained from assigning them causal significance. Understanding the theoretical context in which Kanner's practice was embedded is essential to sorting out how he could have held such seemingly contrary views simultaneously.
This thesis illustrates that Kanner held an explicitly descriptive frame of reference toward his eleven child patients, their parents, and autism. Adolf Meyer, his mentor at Johns Hopkins, trained him to make detailed life-charts under a clinical framework called psychobiology. By understanding that Kanner was a psychobiologist by training, I revisit the original definition of autism as a category of mental disorder and restate its terms. This history illuminates the theoretical context of autism's discovery and has important implications for the first definition of autism amidst shifting theories of childhood mental disorders and the place of the natural sciences in defining them.
Thus far, histories about autism have pointed to descriptions of parents of autistic children with the claim that Kanner abstained from assigning them causal significance. Understanding the theoretical context in which Kanner's practice was embedded is essential to sorting out how he could have held such seemingly contrary views simultaneously.
This thesis illustrates that Kanner held an explicitly descriptive frame of reference toward his eleven child patients, their parents, and autism. Adolf Meyer, his mentor at Johns Hopkins, trained him to make detailed life-charts under a clinical framework called psychobiology. By understanding that Kanner was a psychobiologist by training, I revisit the original definition of autism as a category of mental disorder and restate its terms. This history illuminates the theoretical context of autism's discovery and has important implications for the first definition of autism amidst shifting theories of childhood mental disorders and the place of the natural sciences in defining them.
ContributorsCohmer, Sean (Author) / Hurlbut, James B (Thesis advisor) / Maienschein, Jane (Committee member) / Laubichler, Manfred (Committee member) / Arizona State University (Publisher)
Created2014
Description
During the 1960s, the long-standing idea that traits or behaviors could be
explained by natural selection acting on traits that persisted "for the good of the group" prompted a series of debates about group-level selection and the effectiveness with which natural selection could act at or across multiple levels of biological organization. For some this topic remains contentious, while others consider the debate settled, even while disagreeing about when and how resolution occurred, raising the question: "Why have these debates continued?"
Here I explore the biology, history, and philosophy of the possibility of natural selection operating at levels of biological organization other than the organism by focusing on debates about group-level selection that have occurred since the 1960s. In particular, I use experimental, historical, and synthetic methods to review how the debates have changed, and whether different uses of the same words and concepts can lead to different interpretations of the same experimental data.
I begin with the results of a group-selection experiment I conducted using the parasitoid wasp Nasonia, and discuss how the interpretation depends on how one conceives of and defines a "group." Then I review the history of the group selection controversy and argue that this history is best interpreted as multiple, interrelated debates rather than a single continuous debate. Furthermore, I show how the aspects of these debates that have changed the most are related to theoretical content and empirical data, while disputes related to methods remain largely unchanged. Synthesizing this material, I distinguish four different "approaches" to the study of multilevel selection based on the questions and methods used by researchers, and I use the results of the Nasonia experiment to discuss how each approach can lead to different interpretations of the same experimental data. I argue that this realization can help to explain why debates about group and multilevel selection have persisted for nearly sixty years. Finally, the conclusions of this dissertation apply beyond evolutionary biology by providing an illustration of how key concepts can change over time, and how failing to appreciate this fact can lead to ongoing controversy within a scientific field.
explained by natural selection acting on traits that persisted "for the good of the group" prompted a series of debates about group-level selection and the effectiveness with which natural selection could act at or across multiple levels of biological organization. For some this topic remains contentious, while others consider the debate settled, even while disagreeing about when and how resolution occurred, raising the question: "Why have these debates continued?"
Here I explore the biology, history, and philosophy of the possibility of natural selection operating at levels of biological organization other than the organism by focusing on debates about group-level selection that have occurred since the 1960s. In particular, I use experimental, historical, and synthetic methods to review how the debates have changed, and whether different uses of the same words and concepts can lead to different interpretations of the same experimental data.
I begin with the results of a group-selection experiment I conducted using the parasitoid wasp Nasonia, and discuss how the interpretation depends on how one conceives of and defines a "group." Then I review the history of the group selection controversy and argue that this history is best interpreted as multiple, interrelated debates rather than a single continuous debate. Furthermore, I show how the aspects of these debates that have changed the most are related to theoretical content and empirical data, while disputes related to methods remain largely unchanged. Synthesizing this material, I distinguish four different "approaches" to the study of multilevel selection based on the questions and methods used by researchers, and I use the results of the Nasonia experiment to discuss how each approach can lead to different interpretations of the same experimental data. I argue that this realization can help to explain why debates about group and multilevel selection have persisted for nearly sixty years. Finally, the conclusions of this dissertation apply beyond evolutionary biology by providing an illustration of how key concepts can change over time, and how failing to appreciate this fact can lead to ongoing controversy within a scientific field.
ContributorsDimond, Christopher C (Author) / Collins, James P. (Thesis advisor) / Gadau, Juergen (Committee member) / Laubichler, Manfred (Committee member) / Armendt, Brad (Committee member) / Lynch, John (Committee member) / Arizona State University (Publisher)
Created2014
Description
Natural history is, and was, dependent upon the collection of specimens. In the nineteenth century, American naturalists and institutions of natural history cultivated and maintained extensive collection networks comprised of numerous collectors that provided objects of natural history for study. Effective networks were collaborative in nature, with naturalists such as Spencer Baird of the Smithsonian trading their time and expertise for specimens. The incorporation of Darwinian and Neo-Lamarckian evolutionary theory into natural history in the middle of the century led to dramatic changes in the relationship between naturalists and collectors, as naturalists sought to reconcile their observations within the new evolutionary context. This dissertation uses the careers of collectors Robert Kennicott, Frank Stephens, Edward W. Nelson, E.A. Goldman, and Edmund Heller as case studies in order to evaluate how the changes in the theoretical framework of late nineteenth century natural history led to advances in field practice by assessing how naturalists trained their collectors to meet new demands within the field. Research focused on the correspondence between naturalists and collectors, along with the field notes and applicable publications by collectors. I argue that the changes in natural history necessitated naturalists training their collectors in the basics of biogeography - the study of geographic distribution of organisms, and systematics - the study of the diversity of life - leading to a collaborative relationship in which collectors played an active role in the formation of new biological knowledge. The project concludes that the changes in natural history with regard to theory and practice gradually necessitated a more professional cadre of collectors. Collectors became active agents in the formation of biological knowledge, and instrumental in the formation of a truly systematic natural history. As a result, collectors became de facto field naturalists, the forerunners of the field biologists that dominated the practice of natural history in the early and middle twentieth century.
ContributorsLaubacher, Matthew (Author) / Green, Monica (Thesis advisor) / Laubichler, Manfred (Thesis advisor) / Wright, Johnson Kent (Committee member) / Arizona State University (Publisher)
Created2011
Description
Gene-centric theories of evolution by natural selection have been popularized and remain generally accepted in both scientific and public paradigms. While gene-centrism is certainly parsimonious, its explanations fall short of describing two patterns of evolutionary and social phenomena: the evolution of sex and the evolution of social altruism. I review and analyze current theories on the evolution of sex. I then introduce the conflict presented to gene-centric evolution by social phenomena such as altruism and caste sterility in eusocial insects. I review gene-centric models of inclusive fitness and kin selection proposed by Hamilton and Maynard Smith. Based their assumptions, that relatedness should be equal between sterile workers and reproductives, I present several empirical examples that conflict with their models. Following that, I introduce a unique system of genetic caste determination (GCD) observed in hybrid populations of two sister-species of seed harvester ants, Pogonomyrmex rugosus and Pogonomyrmex barbatus. I review the evidence for GCD in those species, followed by a critique of the current gene-centric models used to explain it. In chapter two I present my own theoretical model that is both simple and extricable in nature to explain the origin, evolution, and maintenance of GCD in Pogonomyrmex. Furthermore, I use that model to fill in the gaps left behind by the contributing authors of the other GCD models. As both populations in my study system formed from inter-specific hybridization, I review modern discussions of heterosis (also called hybrid vigor) and use those to help explain the ecological competitiveness of GCD. I empirically address the inbreeding depression the lineages of GCD must overcome in order to remain ecologically stable, demonstrating that as a result of their unique system of caste determination, GCD lineages have elevated recombination frequencies. I summarize and conclude with an argument for why GCD evolved under selective mechanisms which cannot be considered gene-centric, providing evidence that natural selection can effectively operate on non-heritable genotypes appearing in groups and other social contexts.
ContributorsJacobson, Neal (Author) / Gadau, Juergen (Thesis advisor) / Laubichler, Manfred (Committee member) / Pratt, Stephen (Committee member) / Arizona State University (Publisher)
Created2012
Description
Identity theorists have emphasized the importance of integration across identity domains for psychosocial well-being. There remains little research, however, on associations across identity domains, group differences across identity profiles, and the joint association of multiple identity domains with academic outcomes. This dissertation includes two studies that address these limitations in the identity literature. Study 1, examined the ego-social identity profiles that emerged from ethnic identity exploration and commitment, American identity exploration and commitment, and ego identity integration and confusion among an ethnically diverse sample of emerging adults using latent profile analysis (N = 8,717). Results suggested that an eight-profile solution was the best fit for the data. The profiles demonstrated differences in identity status and salience across identity domains. Significant ethnic, sex, nativity, and age differences were identified in ego-social identity membership. Study 2 focused on the ego-social identity profiles that emerged from the same identity domains among biethnic college students of Latino and European American heritage (N = 401) and how these profiles differed as a function of preferred ethnic label. The association of ego-social identity profile with academic achievement and the moderation by university ethnic composition were examined. Results indicated that a two-profile solution was the best fit to the data in which one profile included participants with general identity achievement across identity domains and one profile included individuals who were approaching the identity formation process in each domain. Ego-social identity profile membership did not differ based on preferred ethnic label. Individuals who had a more integrated identity across domains had higher college grades. University ethnic composition did not significantly moderate this association. Taken together, these two studies highlight the intricacies of identity formation that are overlooked when integration across identity domains is not considered.
ContributorsGonzales-Backen, Melinda Airr (Author) / Dumka, Larry (Thesis advisor) / Millsap, Roger (Committee member) / Roosa, Mark (Committee member) / Yoo, Hyung Chol (Committee member) / Arizona State University (Publisher)
Created2012