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A geochemical evaluation of cryptotephra from Montserrat, Lesser Antilles Arc.
No full textIn volcanic eruptions, magmatic or phreatomagmatic fragmentation transforms the erupting magma into a gas-particle/droplet mixture that is then injected into the atmosphere as an ash plume. The material from this ash plume is then deposited on land or in the ocean as a tephra layer, an unconsolidated, fragmented material, or cryptotephra, which is a tephra layer that is invisible to the naked eye. Tephra has long been used in geochemical studies of volcanic systems to assess how the magma chambers evolve in terms of their composition and volatile content. It is particularly useful as a chronostratigraphic marker that can provide precise age dates for both ice and oceanic cores. This project explores two newly documented cryptotephra deposits from core U1396-1H-4W collected on IODP expedition 340 to the Caribbean Sea, near Montserrat. The overall particle content and composition is documented through point counting. Textural analysis via scanning electron microscopy (SEM) indicates that white glass, mineral fragments, and vesicular pumice fragments are the main constituents of these cryptotephra deposits. A geochemical evaluation of glass particles in both deposits indicates that samples range in composition from rhyolitic to dacitic. The variation in composition of glass particles in core segment 11-15 cm can be attributed to one of two processes: mixing of a more silicic and a more mafic magma in the chamber which feeds the various volcanic complexes on Montserrat, or a relatively fast ascent rate of magma through the crustal column which leads to relatively less degassing until the magma reaches the subaerial environment. The low variance in composition of glass particles in core segment 41-45 cm suggests that the magma either ascended through the conduit at a slower rate and degassed as it rose, or that the magma chamber fractionated significantly before the eruption
Building without Burning: A Case Study and Guide for White Teachers Hoping to Teach about Race and Power.
No full textThis thesis takes a course I taught through the Tufts Experimental College on counternarrative US history as a case study for how to teach about race and power, especially in the moment of Trump and Black Lives Matter, and as a white teacher
The Perceived Benefits and Barriers to Summer Meal Participation in New York City.
No full textOnly 15 percent of U.S. children who receive free and reduced-price lunches during the year access USDA-sponsored free summer meal programs when school is out of session. Previous research has explored parent perceptions of summer meals to understand the underutilization of the program. The present study examined the role that summer meals have in shaping parents’ experiences providing food and children’s experiences eating in the summer with regard to the perceived benefits and barriers to participation. Twenty qualitative semi-structured phone interviews were conducted with parents from Queens, Bronx, and Brooklyn, New York, including both participants and non-participants in summer meals. All interview respondents were recruited through their participation in a separate summer meals survey at their child’s elementary school, where they offered their contact information for follow-up. The interview asked questions about the challenges that parents face providing food in the summer and the perceived benefits or barriers to participating in a free meals program. Interviews were transcribed, coded, and analyzed thematically. Results demonstrated that summer meals reduce financial and psychological stress for parents, foster social support and connections within the community, and improve consumption habits for children. However, awareness of meal programs remains low and some programs may lack cultural inclusivity, preventing families with religious dietary restrictions from participating. On the whole, while the main purpose of summer meals is to reduce food insecurity, the programs provide many additional social and psychological benefits that demonstrate their value to low-income families. Summer meal administrators should incorporate messaging about these advantages into their marketing to leverage support for and participation in the programs, while meal sites should continue innovating ways to improve access to meals for all families
Spatial and Management Characteristics and their Relationship with Borehole Functionality in the Eastern Region, Ghana.
No full textImproved water infrastructure, such as boreholes, contribute to improved health outcomes in rural, low-income settings by increasing the quality and quantity of available drinking water. However, boreholes must be functional to produce the associated health benefits, and an estimated 36% of water systems in sub-Saharan Africa are non-functional. Management and spatial characteristics are thought to affect the ability and motivation of communities to maintain and repair boreholes. In this study, water infrastructure, housing, and survey data were collected from 15 towns in the Eastern Region, Ghana. Borehole functionality was measured using longitudinal data from 3 years. There were a variety of management structures and practices utilized by the study communities, but none of them were significantly correlated with BH functionality. User-reported payment was high (93%) and was positively correlated with BH functionality. Distance to nearby houses and water sources was not correlated to BH functionality. This study revealed that missing BH data was prevalent and spatially biased, which has implications for future cross-sectional studies
“Apruebo Este Mensaje:” How the Language of Political Communication Affects the Political Attitudes of Linguistically Diverse Latino Voters.
No full textEvery election cycle, political campaigns on both sides of the aisle spend millions of dollars on Spanish-language advertising in an effort to appeal to Latino voters. Yet there is no consensus among scholars that using a particular language positively--or negatively--impacts the political attitudes of linguistically diverse Latino voters. Furthermore, in the existing academic field of Latino politics, the framework of analysis has been largely binary: researchers have distinguished only between “Spanish-dominants” and “English-dominants,” with no acknowledgement for the political attitudes and behavior of bilingual Latinos, who make up 36% of the Latino population in the United States today. This study fills this gap by studying how the language of political communication affects the favorability of a non-Latino candidate among bilingual versus English-dominant Latino voters. To do so, I utilized a qualitative methodology and conducted a series of twelve focus groups with Latino-identifying students at Tufts University. In each focus group, participants either viewed a Spanish or English-language advertisement, and were asked to rate their favorability of the candidate and his commitment to the Latino community, as well as respond to a series of discussion questions pertaining to the effect of the language of political communication. The findings from these focus group survey questions and discussions confirmed that bilingual Latinos and English-dominants embrace distinct political attitudes about Spanish-language political communication and partisanship. Furthermore, this research demonstrates that the role of Spanish in Latino identity is changing, and provides practical recommendations for political campaigns to improve their strategies to effectively engage with bilingual and English-dominant Latino voters
Bioelectric Modulation of Membrane Potential in Human Adipose-Derived Stem Cells.
No full textThe role of membrane potential in adipose-derived stem cell (ASC) patterning has yet to be elucidated. To assess the effects of membrane potential modulation on human ASC behavior, ASCs were cultured in 2D treated and with membrane potential-altering drugs such as ivermectin. Additionally, to assess the combined effects of membrane potential modulation in a three-dimensional microenvironment, ASCs were also cultured on silk fibroin sponges and treated with ivermectin. While some experiments showed ivermectin induce an increase in ASC proliferation, others did not show the same effect. Future experiments can be undertaken to evaluate the modulation of membrane potential in ASCs including use of other electroceutical drugs, assessing combined effects of growth factors, and performing experiments in media with defined chloride levels
Clogging in Low Reynolds Number Channel Flow.
No full textThe mechanisms behind particulate clogging are probed by observing microfluidic channel clogging with high speed video microscopy. Results indicate the absence of a dilute-to-dense transition in the low Reynolds number regime, and indicate that steric exclusion at the channel walls causes particulate depletion as flow enters the throat of the channel constrictions
Emergence of Regularities in CTSL.
No full textMy thesis concerns the field of Linguistics. I discuss fundamental questions about language emergence through using data from a young village sign language (Central Taurus Sign Language)
Exploring Services for Ethnic Minority Adolescents: An Ethnographic Study of a Community-Based Asian American Youth Program
No full textAbstract: The purpose of this research study was to explore how a community-based Asian American youth leadership program defines leadership, as well as to examine how that was shaped by staff members' understanding of the cultural context of the youth served by the program. The study was designed as an ethnographic study, using participant observation and staff interviews. Participants included Asian American adolescents who participated in the youth leadership projects, as well as staff members who led these projects. Data analysis followed Spradley's ethnographic methods in three steps: domain, taxonomy, and componential analysis. Six types of different knowledge and skills were identified, with incidental teaching by staff leaders, hands-on practice, and learning for individual life skills identified as the most commonly used strategies. Application of knowledge and understanding of biculturalism were further found to be two core values regarding Asian American youth's leadership development. Further research is recommended to evaluate the effectiveness of the leadership skills and strategies identified, incorporating the perspective of the youth.Thesis (M.A.)--Tufts University, 2018.Submitted to the Dept. of Child Development.Advisor: Jayanthi Mistry.Committee: Francine Jacobs, and Carolyn Rubin.Keywords: Developmental psychology, and Ethnic studies
Developing knowledge in engineering science courses: Sense-making and epistemologies in undergraduate mechanical engineering homework sessions
No full textAbstract: Constructing and applying conceptual knowledge about physical systems is a core activity of practicing mechanical engineers. Yet, studies have shown a surprising proportion of graduating engineering students respond to conceptual questions by recalling fragmented facts and equations; they struggle to reason systematically about the causal mechanisms that drive a phenomenon. One activity where students are expected to develop conceptual engineering knowledge in engineering science courses is during the completion of assigned homework problems. This dissertation examined six undergraduate engineering science homework sessions to identify sense-making conversations that may have lead to conceptual knowledge construction. These episodes of sense-making - or in some cases, only bids for sense-making - were analyzed to understand student shifts from task production to knowledge construction. Participants were also interviewed about homework sessions and other assigned tasks in engineering courses to explore their epistemologies. The interviews showed specifically what students believe counts as knowledge in engineering, how they believe they best develop engineering knowledge, and what pedagogical choices by the instructor students notice as productive for their development of knowledge. Findings have implications for the design of engineering science tasks and future research initiatives about conceptual knowledge building during homework sessions.Thesis (Ph.D.)--Tufts University, 2018.Submitted to the Dept. of Mechanical Engineering.Advisor: Kristen Wendell.Committee: Chris Rogers, David Hammer, and Milo Koretsky.Keywords: Mechanical engineering, Education, and Engineering