Bioculture Journal
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Tolerances and responses of seagrasses to hydrogen sulfide and implications to ecology and restoration
No full textThesis (Ph.D.)--University of Washington, 2015Predicting an individual or species response to climate change, ecosystem disruptions or any environmental change is highly problematic and often requires assumptions. Currently Zostera marina (eelgrass) and other seagrasses have undergone extensive changes within their ecosystems much of which has effected there population size and fecundity. In the Pacific Northwest (PNW) changes have occurred within the ecosystems since the industrial revolution, and correspondingly reductions in the meadows have been observed. Many of these changes are anthropogenic in nature. Bio-matter accumulation, increases in temperature and prevalence of disease are only a few of many factors influencing survival. In the late 1990's and early 2000's Westcott bay, a typical eelgrass habitat, abruptly went extinct. Many hypotheses were developed in hopes of explaining the disappearance, and restoration efforts tried yet failed to re-establish a viable population in the bay. In 2007 I started evaluating Z. marina response to different environmental conditions and as I transitioned into my graduate career I used these and other experiments to explain in part the reductions and extinctions observed. Here, I report on the tolerances of seagrasses found in the PNW to hydrogen sulfide (H2S), its physiological interactions, and implication to restoration and seed banking. Additionally, I report on the concentrations of H2S/sulfide found in embayments throughout the San Juan archipelago and surrounding areas within the Salish Sea (PNW). Based on laboratory experiments I found that eelgrass is highly vulnerable to low concentrations of H2S (LD50 = 334μM). More specifically it was determined that the H2S decreased photosynthetic output and inhibited photosystem II. No reduction in respiration was detected until ~10mM. This is also the case with Phyllospadix scouleri, however based on its physiology and adaptions for a rockier habitat the lethal limit was significantly lower (LD50 = 86μM). Field observations indicate that concentrations vary dramatically based on site location, sediment type and biomatter accumulation, but is highly correlated with eelgrass presence (or absence). And in cases when there are no shoots found concentrations are higher than those observed to be lethal. Sites experiencing high concentrations of sulfide(s) may be a candidate for restoration: capping. In populations which are undergoing reductions seed storage may be necessary, however it is highly problematic, and I report that seed viability decreases with each year of storage and plantation may not be passable after 2 years
Long-term chronology of subsistence and the role of intensive agriculture in the central part of the Korean peninsula during the Late Holocene
No full textThesis (Ph.D.)--University of Washington, 2015The transition from foragers to farmers and the role of intensive rice agriculture have been among the most controversial subjects in Korean archaeology. However, the relatively high acidity of sediment in the Korean peninsula has made it impossible to examine faunal/floral remains directly for tracing the subsistence change. For this reason, many of the studies on the transition heavily relied on the shell middens in the coastal areas, which reflect only a small portion of the overall subsistence in the Korean Peninsula. The subsistence behaviors recorded in numerous large-scale inland habitation sites have been obscured by the overall separation between hunter-gatherer and intensive rice farmer. My dissertation research investigates the role of intensive rice farming as a subsistence strategy in the central part of the prehistoric Korean peninsula using organic geochemical analysis and luminescence dating on potsherds. The central hypothesis of this research is that there was a wide range of resource utilization along with rice farming around 3,400-2,600 BP. This hypothesis contrasts with prevailing rice based models, where climatically driven intensive rice agriculture from 3,400 BP is thought to be the dominant subsistence strategy that drove social complexity. This research focuses on four large-scale inland habitation sites that contain abundant pottery collections to evaluate the central hypothesis as well the prevailing rice-centered model. This research produced critical data for addressing prehistoric subsistence of Korean peninsula and established detailed chronology of subsistence during 3,400-1,800 BP
Development of a Novel Paper-Based Flu Test for Improved Diagnosis at the Point of Care
No full textThesis (Ph.D.)--University of Washington, 2015The development of paper-based diagnostics has surged in recent years, due to the suitability of these tests for use at the point of care. Paper-based diagnostics offer the ability to perform relatively sophisticated chemical processing, but in an automated device that is low in cost, generates a result in a matter of minutes, and can be operated by untrained users in clinics and homes around the world. Influenza infection, or the flu, is one illness that stands to benefit greatly from the improved point-of-care testing afforded by paper-based diagnostics. This commonly occurring infection results in millions of illnesses and thousands of deaths in the U.S. each year, many of which could be prevented or mitigated by timely and effective diagnosis and disease management. Improved point-of-care flu testing could also help reduce inefficient and wasteful healthcare spending, as well as the economic burden of flu due to lost productivity. To this end, we have developed a novel paper-based assay for influenza, based on the detection of the surface protein hemagglutinin. This assay was made possible by the use of novel, recombinant affinity proteins for influenza hemagglutinin, developed by collaborators of the project. Since these “flu binders” represent a significant departure from the mainstay of IgG capture molecules for traditional paper-based assays, the use of these affinity proteins required the in-depth study of protein adsorption to paper and the development of novel immobilization methods. Using the combination of the recombinant flu binders and the immobilization and assay strategies developed herein, we demonstrated a novel paper-based assay for influenza detection that is more sensitive than a traditional lateral flow immunoassay. Additionally, since this assay targets the hemagglutinin protein of influenza, it allows for the possibility for influenza subtyping, which is not available for any influenza rapid diagnostic test on the market. Overall, this work represents a significant development towards improved influenza diagnosis and disease management at the point of care
Weak bond detection in composites using solitary waves
No full textThesis (Master's)--University of Washington, 2015A composite material is composed of fibers embedded in a matrix and is called Fiber Reinforced Plastic (FRP). Particularly, Carbon Fiber Reinforced Plastic (CFRP) has carbon fiber as the reinforcement. It has a high strength-to-weight ratio and is not less susceptible to fatigue or corrosion compared to metallic materials. Therefore, composite materials like CFRP find applications in aerospace industry due to their low weight and advanced mechanical properties. For large scale composite structures, smaller parts often need to be connected together. The connection of these parts could be done either by mechanical joints such as fasteners or by gluing them together using adhesives. This research focuses on bonded composite structures. A prevailing problem in bonded joints is the indeterminate nature of the strength of the adhesive bond. Low strength bonds, i.e., weak bonds, are very difficult to detect and may become the cause of catastrophic failure. Hence, this work aims to develop a technique based on highly nonlinear waves called solitary waves to detect weak bonds. Nonlinear solitary waves can be generated in a 1-D chain of granular crystals, which consists of discrete particles having nonlinear interactions. Solitary waves are high energy packets, which maintain a finite spatial width while traveling. These waves, traveling in the granular chain, can be transmitted into the specimen by making direct contact with the chain. The reflected wave pattern from the specimen can give information about the localized stiffness of the specimen. In this study, two kinds of CFRP specimens are fabricated - one with pristine bond and the other with a weak bond. For making a weak bond specimen, mold release agent is used to coat the surface of CFRP laminate prior to bonding. This coating acts as an impurity at the bondline and is an example of poor surface preparation. First, standard tests such as the three point bending and the end notched flexure tests are conducted to demonstrate that the strength of the bond is reduced due to the presence of the release agent coating. Further, impact test by solitary wave injection is conducted to cause weak bonds to develop delamination and obtain the response of solitary waves reflected from the specimens. We study the reflected wave characteristics for weak bond detection. Two cases are considered; in the first case, two specimens - pristine and weak bond samples, both without having an initial crack - are tested. In the second case, two specimens - pristine and weak bond samples, both with an initial crack - are tested. The results differentiate the weak bond with the pristine bond based on reflected wave characteristics. This study shows promising results indicating the potential of solitary wave-based detection of weak bond for hot spot monitoring of composite-based structures
Responding to Joint Attention Mediates the Relation between Early Imitation and Later Expressive Language in Infants at High and Low Risk for Autism Spectrum Disorder
No full textThesis (Master's)--University of Washington, 2015Infant siblings of children with autism (HR infants) are at greater risk for language delay than infants with typically developing older siblings (LR infants). This study examined the early developmental pathways that underlie language growth in HR and LR infants using a prospective longitudinal design. Two early social-communicative skills that predict expressive language in both children with autism and those with typical development are motor imitation (i.e., imitating the actions of others) and responding to joint attention (i.e., following the direction of another person's interest; RJA). We hypothesized that: (1) RJA would mediate the association between imitation and expressive language over the first two years of life, and (2) mediation would be stronger for HR infants than LR infants. Imitation, RJA, and expressive vocabulary were assessed in 84 infants (50 HR) between 12 and 18 months. Results revealed that 15-month RJA mediated the association between 12-month imitation and 18-month expressive vocabulary, even after controlling for earlier levels of RJA and language. A conditional direct effect was also found; after accounting for the mediation effect, 12-month imitation directly affected 18-month expressive vocabulary for LR, but not HR, infants. These results support a developmental sequence for language development that can inform future intervention efforts for children at risk for developmental challenges
The Effect of Visual Design and Information Content on Readers’ Assessments of API Reference Topics
No full textThesis (Ph.D.)--University of Washington, 2015Software developers must learn and use an increasing number of application-programming interfaces (APIs) to create applications and web sites. To apply these APIs in the increasingly short development time that modern markets require, software developers must learn to use APIs quickly. In the process of learning and using APIs, software developers must find and evaluate many API documentation topics, which can vary greatly in their visual design and the information they contain. This study applied a task-based, experimental methodology to measure the effects that variations in the visual design and information concepts used in API reference topics have on software developers’ speed and accuracy when they assess the topics’ relevance, and their perceptions of the topics. In an Internet-based, remote study, participants performed four information-seeking tasks in which they decided whether an API reference topic was relevant to a question presented in a typical programming scenario. The study analyzed 698 individual information-seeking tasks from 201 software developers who lived in 30 different countries and who were proficient in English. Variations in the visual design elements of API reference topics did not significantly affect the time required to assess the topics’ relevance to the information-seeking task yet the variations significantly influenced participants’ assessments of the topics’ credibility and professional appearance. Variations in the information concepts presented in the API reference topics, on the other hand, significantly influenced both the time participants took to evaluate the topics’ relevance and the participants’ assessments of the topics’ credibility and professional appearance. This study contributes critically needed empirical data in an under-studied area concerning how document design elements influence readers’ performance and perception of API reference topics. This study also updates best-practice recommendations for practitioners who write API reference topics to help them prioritize their documentation efforts. Finally, the study provides information about tools and methods that could provide guidance for testing and improving API documentation and other types of documents and in other contexts
Walking out of the Mountain: Cultural Identification and Education of Rural Migrant Muslim Students in Northwest China
No full textThesis (Ph.D.)--University of Washington, 2015-12The economic boom in China has brought major changes in its geographical and cultural landscapes. Significant among these is the magnitude and directionality of demographic mobility. It is estimated that 170-180 million rural populations come to the cities to find jobs and live their lives. Hui (10.6 million), one of the largest ethnic minority groups in China, and Dongxiang are very much a part of this mobility of migrating from rural to urban areas in Northwest China. After moving to the urban environment, communication with other ethnic groups, predominantly the Han (the majority ethnic group in China), becomes inevitable, even though the Hui and Dongxiang tend to live in separate communities in the cities. Hui and Dongxiang children attended mostly mixed-ethnicity rather than single-ethnicity schools. Contradictions of rural-urban differences, ethnicity and religion sparkle wide attention and discussion. This study explored this migration phenomenon from the perspectives of the education, social adaption, and identity development of a small group of Hui and Dongxiang students who have migrated to the city from rural communities. The seven participants in the study went to seventh and eighth grades attending a middle school in Lanzhou. Qualitative research analyses of data generated from narrative stories, thematic photos, group discussions, semi-structured interviews, and field observations produced four major findings. These were: 1) Islam and its denominations are deep influences on migrant Hui and Dongxiang students’ identification, and caused some notable conflicts with the urban and school culture. They penetrated in many aspects of their lives such as clothing, dietary restrictions, and religious practice and literacy. 2) There are some salient differences in the education of and adaptation to urban life of male and females. The roles of females in family, marriage and careers resulted in pressures and motivation on their education and adaption to urban life. 3) Rural migrant Hui and Dongxiang students are strongly attached to their rural identity even as they adapt to the urban life and culture. They developed complex and reflective response on their urban and previous living. 4) Hui and Dongxiang students also experience heavy pressures from standardized testing and urban schooling. Based on the results, some recommendations for further research and practice were suggested. These included addressing multicultural education in educational policies; developing a system of differentiated citizenship for Hui and Dongxiang migrant students to ensure more educational equity; and continuing to study Hui and Dongxiang students in greater numbers, in a variety of educating settings, and in different stages of their entering and adaption to living and learning in urban cities and schools. Other ethnic minorities in China should be similarly studied. The results of such research could contribute significantly to advancing the cause of educational equity, justice, and excellence (as well as national unity among diverse group) for ethnic minorities in China
Competition between non-native brook trout and coho salmon in the Elwha River, WA during dam removal
No full textThesis (Master's)--University of Washington, 2015The removal of two dams on the Elwha River, WA is the largest dam removal project in US history. A major goal of this project is to restore historically abundant populations of Pacific salmon to the river, so it is important to know if competition between resident and anadromous species could inhibit salmon recolonization. We investigated competitive interactions in laboratory streams to determine how species, size, and group size affected competitive dominance and determined the level of habitat and prey resource use overlap to indicate the potential for competition in reaches of the Elwha River. Coho salmon were competitively dominant over brook trout regardless of size difference or group size, and will likely outcompete brook trout in the wild if resources become limited. Prey resource use overlap indicated potential for competition in sympatric areas, but density and distribution patterns did not suggest that competition was occurring at the reach scale
Scaffolding Student Learning in the Discipline-Specific Knowledge through Contemporary Science Practices: Developing High-School Students’ Epidemiologic Reasoning through Data Analysis
No full textThesis (Ph.D.)--University of Washington, 2015Science is a disciplined practice about knowing puzzling observations and unknown phenomena. Scientific knowledge of the product is applied to develop technological artifacts and solve complex problems in society. Scientific practices are undeniably relevant to our economy, civic activity, and personal lives, and thus public education should help children acquire scientific knowledge and recognize the values in relation to their own lives and civil society. Likewise, developing scientific thinking skills is valuable not only for becoming a scientist, but also for becoming a citizen who is able to critically evaluate everyday information, select and apply only the trustworthy, and make wise judgments in their personal and cultural goals as well as for obtaining jobs that require complex problem solving and creative working in the current knowledge-based economy and rapid-changing world. To develop students’ scientific thinking, science instruction should focus not only on scientific knowledge and inquiry processes, but also on its epistemological aspects including the forms of causal explanations and methodological choices along with epistemic aims and values under the social circumstances in focal practices. In this perspective, disciplinary knowledge involves heterogeneous elements including material, cognitive, social, and cultural ones and the formation differs across practices. Without developing such discipline-specific knowledge, students cannot enough deeply engage in scientific “practices” and understand the true values of scientific enterprises. In this interest, this dissertation explores instructional approaches to make student engagement in scientific investigations more authentic or disciplinary. The present dissertation work is comprised of three research questions as stand-alone studies written for separate publication. All of the studies discuss different theoretical aspects related to disciplinary engagement in epidemiologic inquiry and student development in epidemiologic reasoning. The first chapter reviews literature on epistemological instruction and explores theoretical frameworks for epistemically-guided instruction. The second chapter explores methodological strategies to elicit students’ disciplinary understanding and demonstrates an approach with a case study in which students engaged in a curriculum unit for an epidemiologic investigation. The last chapter directs the focus into scientific reasoning and demonstrates how the curriculum unit and its scaffolds helped students develop epidemiologic reasoning with a focus on population-based reasoning