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Title: Managing carrot foliar diseases in commercial production fields in Michigan
Creator: Donne, Irene Mariel
Date: 2017
Collection: Electronic Theses & Dissertations
Description: "Fungal foliar diseases caused by Alternaria dauci and Cercospora carotae occur annually on carrots. Our goal was to update the disease management tactics by: 1) Testing OMRI-approved and conventional fungicides and 2) Evaluating TOM-CAST. Trials were conducted in 2015 and 2016. Disease severity was visually assessed weekly using the Horsfall-Barratt scale and a petiole health scale; the area under the disease progress curve (AUDPC) was calculated for these parameters. Root yield was...
Show more"Fungal foliar diseases caused by Alternaria dauci and Cercospora carotae occur annually on carrots. Our goal was to update the disease management tactics by: 1) Testing OMRI-approved and conventional fungicides and 2) Evaluating TOM-CAST. Trials were conducted in 2015 and 2016. Disease severity was visually assessed weekly using the Horsfall-Barratt scale and a petiole health scale; the area under the disease progress curve (AUDPC) was calculated for these parameters. Root yield was determined at harvest. Based on AUDPC results obtained in 2015 and 2016, the copperbased fungicides (copper hydroxide and copper hydroxide + copper oxychloride) were the only OMRI-approved products that significantly and consistently limited foliar blight. On the final assessment dates in both years, all conventional fungicides limited foliar and petiole blighting compared to the control with one exception; the propiconazole treatment in 2016 was similar to the control for petiole health. Yields differed significantly among the conventional treatments in 2016 but not in 2015. All treatments yielded significantly higher than the control except for iprodione. Treatments of pyraclostrobin + boscalid, fluxapyroxad + pyraclostrobin, and boscalid had statistically higher yields than penthiopyrad, iprodione, and propiconazole. TOM-CAST 15 and 25 DSV fungicide application schedules effectively reduced foliar blighting in 2015 under relatively light disease pressure. However, the TOM-CAST 25 DSV schedule did not adequately limit disease in 2016 when disease pressure was increased. Recently registered fungicides such as penthiopyrad and fluxapyroxad + pyraclostrobin and using TOM-CAST at the more conservative spray threshold of 15 DSV can help growers limit fungal foliar blight in years with higher disease pressure."--Page ii.
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Title: Social-ecological systems, values, and the science of "people management"
Creator: Piso, Zachary Amedeo
Date: 2017
Collection: Electronic Theses & Dissertations
Description: This dissertation interrogates a shift in environmental science, policy, and management toward conceptualizing the environment as a social-ecological system. Social-ecological systems science reflects an interdisciplinary effort to understand how individuals and communities achieve their environmental goals through the institutions that they maintain. Though the paradigmatic institutions concern economic behavior (e.g. property rights institutions), the field embraces the social sciences...
Show moreThis dissertation interrogates a shift in environmental science, policy, and management toward conceptualizing the environment as a social-ecological system. Social-ecological systems science reflects an interdisciplinary effort to understand how individuals and communities achieve their environmental goals through the institutions that they maintain. Though the paradigmatic institutions concern economic behavior (e.g. property rights institutions), the field embraces the social sciences broadly, with contributions from sociology, anthropology, geography, political science, and so on. That said, social science is fairly narrowly conceived; leaders in the field stress that they are studying social mechanisms in order to predict and manage social behavior. In a popular textbook on the subject, Fikret Berkes and Carl Folke stress that "resource management is people management" and call for a social science of this management.Social-ecological systems scientists have generally neglected the ethics of people management-for the most part they subscribe to a fairly typical fact/value dichotomy according to which scientists describe social-ecological systems while managers and policymakers prescribe actions in light of these descriptions. Following several philosophical traditions (in particular pragmatist philosophy of science), I call attention to the ways that social-ecological systems science is value-laden. I take environmental pragmatism to provide a roadmap for conducting social-ecological systems science ethically. Environmental pragmatists stress that science is always embedded in practical problem-solving activities that presuppose particular goals for, and side constraints to, inquiry. Many traditions in the philosophy of environmental science embrace social science for the specific role of facilitating this deliberation, but these traditions do not seem to anticipate the explanatory ambitions of social sciences. This leaves unaddressed several pertinent questions about how social explanations work (i.e. how functional distinction structure inquiry), which have very practical implications for which social science disciplines should be included in a collaboration and how social and ecological knowledge should be integrated. For example, most social situations are characterized by property rights institutions, cultural traditions, political alliances, and other social institutions within the purview of particular social science disciplines, but researchers are not reflexive about whether to explain environmental change according to one set of practices or another.The dissertation traverses the following terrain: the first chapter more carefully motivates the questions above regarding the need for ethics and the promise, but present inadequacy, of environmental pragmatism to meet this need. Chapter two attends to Dewey's theory of inquiry, in particular the dialogical dimension of inquiry that authorizes warranted assertions. Through reflection on Daniel Bromley's volitional pragmatism and a debate between Richard Rorty and hermeneutic social scientists, chapter three attends to the way that social science structures inquiry in order to intervene in the normative practices of a community. Chapter four analyzes social-ecological explanations in order to locate normative and evaluative assumptions that should be accountable to democratic deliberation. Finally, chapter five redescribes interdisciplinary integration as an ethical project where decisions about the centering and decentering of different sciences is as much ethical as epistemological.
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Title: The meaning of teaching mathematics : teacher positionings as embedded in algebra teachers' guides
Creator: Suh, Heejoo
Date: 2017
Collection: Electronic Theses & Dissertations
Description: Teacher educators have been examining the professional status of teaching, including defining central practices of teaching, comparing teaching to other professions, and understanding teachers’ own perspective via interviews, surveys, and observations. The present study intends to contribute to the discussion by examining the meaning of teaching as reflected in teachers’ guides. I chose to examine teachers’ guides because they are known to have impact on teachers. Being a resource that is...
Show moreTeacher educators have been examining the professional status of teaching, including defining central practices of teaching, comparing teaching to other professions, and understanding teachers’ own perspective via interviews, surveys, and observations. The present study intends to contribute to the discussion by examining the meaning of teaching as reflected in teachers’ guides. I chose to examine teachers’ guides because they are known to have impact on teachers. Being a resource that is close to teachers’ everyday practices, curriculum materials inspire teachers with what they could do in their classroom. Educators intending large-scale educational reform pay attention to curriculum materials. Careful use of linguistic features therein could enhance thus further support teachers’ guides in effective communication with teachers.I investigated four 8 th grade Algebra teachers’ guides - TG, selectively chosen to represent variety. Drawing on positioning theory, I observed positionings regularly appearing in each of those four. Then I turned to idiosyncratically-observable positionings. Two research questions sought understanding of what teaching mathematics entails as presented in the TGs, hence how each guide constructs teaching mathematics. Last, I examined the guides’ linguistic features. This was for understanding the degree of teacher professional judgment acknowledged by the guides.My results indicated that, as constructed by each guide, teaching mathematics does not differ much across the guides. Those guides presented various types of knowledge as entailed in teaching mathematics. Compared to aspects on teacher professionalism in the literature, the guides occasionally addressed teacher research, interaction with colleagues, utilizing knowledge, and acknowledging uncertainty. In addressing these aspects, the guides in most cases did so with insufficient support. Examining idiosyncratic positionings, I found two types: i) positionings occurred idiosyncratic only, and ii) positionings occurred idiosyncratically in addition to their regular appearance. The latter can be classified into two types: a) one that succeeds the context of the communication actions associated with the general positioning, and b) one dissociated from the context. My linguistic examination of the guides suggested that they varied in their use of voice. Some are more directive, others are more suggestive, indicating different levels of acknowledgement of teachers’ professional judgment. In this dissertation’s last chapter, I present ways in which this study contributes to understanding of curriculum materials and of teacher professionalism. I end this dissertation with implications for curriculum authors, teachers, teacher educators, and researchers.
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Title: Exploring the possibilities of Teachtown MKE : using local cultural institutions to support novice teachers' access to community resources
Creator: Shattuck, Tamara M.
Date: 2017
Collection: Electronic Theses & Dissertations
Description: Cultural institutions have the capacity to provide teachers with material resources for curriculum use in the classroom, professional support through connection to professional learning communities, promotion of self-confidence in teaching, and gains in subject content knowledge. There is building evidence that these types of support systems help novice teachers (i.e., teachers in their first three year of teaching), however many teachers do not have access to such support. And while access...
Show moreCultural institutions have the capacity to provide teachers with material resources for curriculum use in the classroom, professional support through connection to professional learning communities, promotion of self-confidence in teaching, and gains in subject content knowledge. There is building evidence that these types of support systems help novice teachers (i.e., teachers in their first three year of teaching), however many teachers do not have access to such support. And while access to resources is important for novice teachers, there is also evidence that access does not guarantee the use of resources. This descriptive study explores the inclusion of cultural institutions as partners in novice teacher support programs though the investigation of Milwaukee, Wisconsin's Key to the City Pass (KCP), which provides new teachers access to over 22 local cultural institutions. I also investigate how novice teachers develop and use the skill of relational agency -the ability to "work fluidly across professional boundaries" (Edwards, 2005a p. 177) and understand the utility of materials for problem solving. I hypothesize building the skill of relational agency helps novice teachers' better access KCP resources for professional use. Thus, four research questions drive this study; 1) How do teachers use KCP benefits? 2) Do teachers who participate in the KCP program incorporate community/cultural institution resources in their teaching practices, and if so how? 3) What barriers exist, and how can the KCP program be made more accessible for teachers? 4) Do participant teachers display the skill of relational agency, does this skill apply to KCP use? I used both quantitative and qualitative methods to analyze data and document teachers' use of the KCP through: (1) a teacher survey, (2) semi-structured focus group interviews, and (3) case study teacher interviews and artifact analysis. The quantitative survey data was analyzed first to gather general patterns of KCP use across participant teachers. I analyzed survey data using descriptive and inferential statistics. The qualitative data was analyzed in a second phase to gather information about how teachers use KCP resources. For the qualitative data analysis, I used deductive coding. Findings indicate that participants were mostly using the KCP program for personal reasons (e.g., trips with friends and family), and that they were able to connect with the local community through these trips. Through personal trips, teachers were also able to assess whether taking field trips to certain cultural institutions was appropriate for their students. Few teachers used the skill of relational agency in connection to the KCP and noted they were more likely to use cultural institution resources if they were clearly connected with state and district standards. Teachers were also more likely to use cultural institution resources if they had the opportunity to collaborate with cultural institution staff. This study enabled me to observe barriers to KCP use before generalizing how such a program might be created in other cities. Which in turn allowed me to understand the steps other cities should take in order to build stronger partnerships. Based on my findings of the barriers to KCP use I suggest cities who wish to form partnership programs: 1) gather input from all constituents, 2) create a strong mission statement, 3) connect to district wide initiatives, and 4) ensure a pathway for clear and continual communication between partners and participants.
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Title: Solid-state nuclear magnetic resonance studies of the structures, membrane locations, cholesterol contact, and membrane motions of membrane-associated HIV Fusion Peptide (HFP
Creator: Jia, Lihui (Scientist)
Date: 2017
Collection: Electronic Theses & Dissertations
Description: Membrane fusion is the key step during HIV viral entry to cells, and the process is catalyzed by HIV membrane fusion protein gp41. HFP is the ~25-residue N-terminal domain of gp41 and is required for membrane fusion with significant decreases in fusion activity with point mutations. Both viral and host cell membrane contain ~30mol % cholesterol (CHOL), and HFP induced fusion is faster in membrane with CHOL. However, how HFP interacts with membrane lipids and CHOL is unknown. In this thesis,...
Show moreMembrane fusion is the key step during HIV viral entry to cells, and the process is catalyzed by HIV membrane fusion protein gp41. HFP is the ~25-residue N-terminal domain of gp41 and is required for membrane fusion with significant decreases in fusion activity with point mutations. Both viral and host cell membrane contain ~30mol % cholesterol (CHOL), and HFP induced fusion is faster in membrane with CHOL. However, how HFP interacts with membrane lipids and CHOL is unknown. In this thesis, we used the newly developed 13C-2H Rotational Echo Double Resonance (REDOR) solid-state NMR method to study the membrane location of HFP in chemically-native membrane environment. HFP is 13CO labeled at specific residue, and the membrane is deuterated at specific regions of the membrane using selective regions deuterated phosphatidylcholine (PC) and CHOL. We study HFP wild type, HFP_V2E and L9R mutants because these two mutants eliminate and decrease fusion respectively. HFP is predominantly β sheet structure in bilayer membrane for both HFP wild type and HFP_V2E mutant, HFP_L9R has a different structure and is likely helical. Both HFP and HFP_V2E mutant have major deeply-inserted membrane location contacting membrane center and minor shallowly-inserted membrane location contacting half way of one membrane leaflet. The HFP_V2E mutant has bigger fraction of molecules with shallower membrane location, which is consistent with the strong correlation between membrane location insertion depth and the peptide fusogenicity. HFP_L9R mutant has majorly deeply inserted into membrane.By comparing the HFP- PC and HFP- CHOL contact, there is preferential contact between HFP and CHOL vs PC at several residues including G5, G10 and G16. The free energy difference for contacting PC vs CHOL is ~ 0.57(5) kcal.mol-1 for T= 300K. HFP- CHOL contact geometry is successfully modeled by Swiss Dock and YASARA energy minimization with two strands antiparallel HFP (1→16/16→1 registry). There are two energetically favorable binding models between HFP and CHOL, from docking, energy minimization and consistency with REDOR results. The contact models reveal tilted and curved-up tail orientation of Chol_d7. Fusion may be catalyzed by matching the curvature of lipids contacting HFPs with the membrane curvature during the fusion intermediates like the stalk. Membrane motion perturbation by HFP is studied by static deuterium NMR from deuterium powder pattern spectrum, order parameter profile and T2 relaxation time. The DMPC-d54 spectrum becomes ~10% narrower in membrane without CHOL with 4% HFP and in membrane with 33% CHOL with 1% HFP. Accordingly, the order parameter of lipid acyl chain becomes ~ 1-10% disordered by HFP. However, the spectrum becomes 20% broader in membrane with 33% CHOL with 4% HFP, and the order parameter of lipid acyl chain becomes ~ 20- 30% ordered by HFP. With HFP at 37 °C, DMPC-d54 T2 decreases ~ 70 %, and the CHOL T2 decreases ~ 30%. T2 reduction is probably associated with increased membrane curvature induced by HFP. With greater membrane curvature, the C-D bond will experience more orientation diversity relative to the external magnetic field. Thus, the quadrupolar field will have greater change, leading to faster relaxation and shorter T2. Gp41_V2E mutant eliminates cell-cell fusion. Our CD spectroscopy studies show that the FPHM_V2E mutant is helical and the melting temperature is above 90 °C in 10mM Tris buffer + 0.2 % SDS at pH 7.4. Protein is trimer and induces no lipid mixing in PC: CHOL= 2:1 vesicles.
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Title: The carbon sequestration and soil respiration after land use conversion in biofuel cropping ecosystems
Creator: Su, Yahn-Jauh
Date: 2017
Collection: Electronic Theses & Dissertations
Description: Global climate change alters Earth's carbon, hydrological and energy cycles from local to global scales, changing our climate patterns and impacting our lifestyles and prosperity. The development of bioenergy may partially mitigate the release of carbon dioxide during the combustion of fossil fuel. However, the carbon emissions from the bioenergy-induced land use change have long been debated and it is not certain whether they really represent a reduction of carbon emission. In this study, I...
Show moreGlobal climate change alters Earth's carbon, hydrological and energy cycles from local to global scales, changing our climate patterns and impacting our lifestyles and prosperity. The development of bioenergy may partially mitigate the release of carbon dioxide during the combustion of fossil fuel. However, the carbon emissions from the bioenergy-induced land use change have long been debated and it is not certain whether they really represent a reduction of carbon emission. In this study, I monitored the components of the net ecosystem exchange (NEE) of CO2, including gross primary production (GPP), ecosystem respiration (Reco), total soil respiration (Rs), autotrophic soil respiration (Ra) and heterotrophic soil respiration (Rh), to understand their responses to climate variability and in particular a severe drought event. I studied three major bioenergy crops (continuous corn, switchgrass and restored multicultural prairie) on fields with two different land use histories (conventional corn-soybean rotation and Conservation Reserve Program brome grass fields). I found that the amplitude, the duration and the seasonality of microclimatic variables (temperature and precipitation) were important for the carbon dynamics in the bioenergy cropping systems. The soil water content affected the annual NEE, GPP and Reco although it did not have strong correlations with these components of carbon fluxes at short-term scale. The short-term (1-2 week) normal summer water deficit may affect annual NEE while long-term (spring-summer) drought may change the community structure and affect the carbon cycling processes in the following years. The temperature sensitivities of soil respiration were shifted within and between years. In addition, crop types and land use histories affect the responses of ecosystem to climate events. The different phenology between annual and perennial crops and the establishment of dense root systems in perennial crops can change the ratio of the components of NEE and change the direction and the amounts of net ecosystem carbon flux. Annual and perennial crops have different strategies responding to different climate scenarios and their combinations. The monitoring of climate patterns at intra-annual scale is required to understand how the ecosystem respond to climate change.
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Title: Dynamic network analysis with applications to functional neural connectivity
Creator: Golibagh Mahyari, Arash
Date: 2017
Collection: Electronic Theses & Dissertations
Description: "Contemporary neuroimaging techniques provide neural activity recordings with increasing spatial and temporal resolution yielding rich multichannel datasets that can be exploited for detailed description of anatomical and functional connectivity patterns in the brain. Studies indicate that the changes in functional connectivity patterns across spatial and temporal scales play an important role in a wide range of cognitive and executive processes such as memory and attention as well as in the...
Show more"Contemporary neuroimaging techniques provide neural activity recordings with increasing spatial and temporal resolution yielding rich multichannel datasets that can be exploited for detailed description of anatomical and functional connectivity patterns in the brain. Studies indicate that the changes in functional connectivity patterns across spatial and temporal scales play an important role in a wide range of cognitive and executive processes such as memory and attention as well as in the understanding the causes of many neural diseases and psychopathologies such as epilepsy, Alzheimers, Parkinsons and schizophrenia. Early work in the area was limited to the analysis of static brain networks obtained through averaging long-term functional connectivity, thus neglecting possible time-varying connections. There is growing evidence that functional networks dynamically reorganize and coordinate on millisecond scale for the execution of mental processes. Functional networks consist of distinct network states, where each state is defined as a period of time during which the network topology is quasi-stationary. For this reason, there has been an interest in characterizing the dynamics of functional networks using high temporal resolution electroencephalogram recordings. In this thesis, dynamic functional connectivity networks are represented by multiway arrays, tensors, which are able to capture the complete topological structure of the networks. This thesis proposes new methods for both tracking the changes in these dynamic networks and characterizing or summarizing the network states. In order to achieve this goal, a Tucker decomposition based approach is introduced for detecting the change points for task-based electroencephalogram (EEG) functional connectivity networks through calculating the subspace distance between consecutive time steps. This is followed by a tensor-matrix projection based approach for summarizing multiple networks within a time interval. Tensor based summarization approaches do not necessarily result in sparse network and succinct states. Moreover, subspace based summarizations tend to capture the background brain activity more than the low energy sparse activations. For this reason, we propose utilizing the sparse common component and innovations (SCCI) model which simultaneously finds the sparse common component of multiple signals. However, as the number of signals in the model increases, this becomes computationally prohibitive. In this thesis, a hierarchical algorithm to recover the common component in the SCCI model is proposed for large number of signals. The hierarchical recovery of SCCI model solves the time and memory limitations at the expense of a slight decrease in the accuracy. This hierarchical model is used to separate the common and innovation components of functional connectivity networks across time. The innovation components are tracked over time to detect the change points, and the common component of the detected network states are used to obtain the network summarization. SCCI recovery algorithm finds the sparse representation of the common and innovation components of signals with respect to pre-determined dictionaries. However, input signals are not always well-represented by pre-determined dictionaries. In this thesis, a structured dictionary learning algorithm for SCCI model is developed. The proposed method is applied to EEG data collected during a study of error monitoring where two different types of brain responses are elicited in response to the stimulus. The learned dictionaries can discriminate between the response types and extract the error-related potentials (ERP) corresponding to the two responses."--Pages ii-iii.
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Title: Dual role of PU.1 in enhancer priming in macrophages
Creator: Tagore, Mohita Malay
Date: 2017
Collection: Electronic Theses & Dissertations
Description: All multicellular organisms arise from a single-celled zygote by the precise execution of a gene expression program which ensures appropriate cell identity. This process is particularly challenging in eukaryotic cells since eukaryotic DNA is packaged by architectural proteins called histones into chromatin, which might act as a barrier to the transcriptional machinery. Macrophages are cells of the immune system which undergo rapid, large scale changes in gene expression in response to...
Show moreAll multicellular organisms arise from a single-celled zygote by the precise execution of a gene expression program which ensures appropriate cell identity. This process is particularly challenging in eukaryotic cells since eukaryotic DNA is packaged by architectural proteins called histones into chromatin, which might act as a barrier to the transcriptional machinery. Macrophages are cells of the immune system which undergo rapid, large scale changes in gene expression in response to bacterial or viral challenge. This makes macrophages an excellent model for studying cell-type specific as well as inducible gene expression. Studies at the genome-wide level have shown that distal regulatory elements like enhancers play an essential role in determining the macrophage inducible response to microbial challenge. Further, lineage-specific transcription factors like PU.1 and C/EBPβ are known to bind inducible enhancers prior to gene induction in resting macrophages. Earlier studies using genome-wide approaches indicate that PU.1 is able to interact with chromatin, thus functioning as a 'pioneer factor' in macrophages. However, not much is known about the mechanism by which PU.1 keeps enhancers accessible prior to gene induction in resting macrophages. Using bone-marrow derived primary mouse macrophage cells as well as PU.1 deficient cell lines, my work highlights the changes in chromatin associated with PU.1 binding during macrophage differentiation as well as in response to bacterial infection. Using a quantitative nucleosome occupancy assay, we reported that PU.1 binding correlates with low nucleosome occupancy at an inducible enhancer in resting macrophages. Further upon induction with an appropriate stimulus, nucleosomes are stably evicted from the distal enhancer and the corresponding gene can be induced. More importantly, my results suggest that lack of PU.1 binding renders regulatory regions (enhancers and promoters) of inducible genes susceptible to heterochromatin formation and silencing by Polycomb repressive complex 2 (PRC2) in differentiated macrophages. PRC2-mediated silencing is also associated with an increase in nucleosome occupancy at the target regions and the corresponding genes cannot be induced. Results obtained from this research will provide important insights into the role of lineage-specific transcription factors at regulatory elements both during normal development and disease.
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Title: Inside practice-based teacher education : a study of one teacher educator's practice
Creator: Muirhead, Faith
Date: 2018
Collection: Electronic Theses & Dissertations
Description: "This dissertation builds on research about practice-based teacher preparation (e.g., Ball & Cohen, 1999; Ball, Sleep, Boerst, & Bass, 2009; Graziani, 2005; Heibert, Morris, Berk, & Jansen, 2007; Lampert, 2010), formative feedback (e.g., Black & Wiliam, 1998; Carless, Salter, Yang, & Lam, 2011; Evans, 2013; Hattie & Timperley, 2007; Kluger & DeNisi, 1996), teacher noticing, (e.g., van Es, 2011; van Es & Sherin, 2008; Sherin, Jacobs, & Philipp, 2011), and positioning theory (e.g., Esmonde,...
Show more"This dissertation builds on research about practice-based teacher preparation (e.g., Ball & Cohen, 1999; Ball, Sleep, Boerst, & Bass, 2009; Graziani, 2005; Heibert, Morris, Berk, & Jansen, 2007; Lampert, 2010), formative feedback (e.g., Black & Wiliam, 1998; Carless, Salter, Yang, & Lam, 2011; Evans, 2013; Hattie & Timperley, 2007; Kluger & DeNisi, 1996), teacher noticing, (e.g., van Es, 2011; van Es & Sherin, 2008; Sherin, Jacobs, & Philipp, 2011), and positioning theory (e.g., Esmonde, 2009; Gresalfi & Cobb, 2006; Harré & van Langenhove, 1991; Herbel-Eisenmann & Wagner, 2010; Herbel-Eisenmann, Wagner, & Cortes, 2010; Wagner & Herbel-Eisenmann, 2009). In particular, I focus on how prospective elementary mathematics teachers are prepared, through a study of one teacher educator's practice. This dissertation is a self-study during a practice-based mathematics methods course for prospective elementary school teachers. Study participants consist of prospective elementary teachers (PTs) who were seniors enrolled in a mathematics methods course at a large Midwestern university. The data for this dissertation includes my lesson plans, videos of each class meeting, prospective teachers' assignments including videotaped lessons, the feedback I provided prospective teachers on assignments and teaching, and my own reflections on teaching. This dissertation contains an introductory chapter, concluding chapter, and three standalone manuscripts. Each manuscript examined a different aspect of my practice as a teacher educator. Each manuscript included a review of relevant literature, data collection, analysis, results, and discussion. Research on practice-based teaching viewed through the lens of examining my own practice provides the thread that sews the manuscripts in this dissertation together. The first manuscript details a lesson-planning tool co-edited with study participants. The tool helped PTs focus attention on student ideas and learning, the mathematical point of the lesson, and the facilitation of mathematically rich discussions. The tool draws liberally on research about lesson planning, orchestrating discussions, and attending to student thinking. The PT collaboration on this tool helped me to see the power of including the PTs' voices in their learning. The second manuscript is an empirical study examining the characteristics of effective feedback in teacher education. I argue that teacher education is a hybrid space where feedback practices bridge both K-12 and higher education contexts. I analyze the feedback I provided to prospective teachers, the characteristics of feedback that participants took up and used to further their learning, and the characteristics of feedback that closed down opportunities for further learning. The third manuscript is an empirical study that draws on the Learning to Notice Framework (van Es, 2011), which I combine with positioning theory (e.g. Harré & van Langenhove, 1991). These theories guide my analysis of student interviews collected in my methods course. Positioning theory points out the links between the ways PTs position students in their written analysis of the interviews and through their instructional decisions. I identify and define both explicit and implicit positioning and argue that static explicit positioning influences PTs' instructional choices and limits the opportunities PTs' students have to learn. I propose a framework for learning to notice positioning in teacher preparation--both for teacher educators and PTs."--Pages ii-iii.
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Title: Protease-containing membranes for rapid, controlled antibody digestion prior to mass spectrometry analysis
Creator: Pang, Yongle
Date: 2017
Collection: Electronic Theses & Dissertations
Description: "Monoclonal antibodies are the fastest growing class of therapeutic drugs because of their high specificities to targeQt cells. Facile analysis of therapeutic mAbs and their post-translational modifications (PTMs) is essential for quality control, and mass spectrometry (MS) is the most powerful tool for antibody characterization. Conventional antibody characterization workflows contain an in-solution digestion step, which is labor-intensive and time-consuming. Protease-containing membranes...
Show more"Monoclonal antibodies are the fastest growing class of therapeutic drugs because of their high specificities to targeQt cells. Facile analysis of therapeutic mAbs and their post-translational modifications (PTMs) is essential for quality control, and mass spectrometry (MS) is the most powerful tool for antibody characterization. Conventional antibody characterization workflows contain an in-solution digestion step, which is labor-intensive and time-consuming. Protease-containing membranes are an attractive alternative platform for protein digestion because of their high local enzyme concentrations, short radial diffusion distances, rapid convection in pores, simple fabrication and low cost. Additionally, variation of protein residence time in the membrane gives control over the size of proteolytic peptides. This research focuses on developing workflows for monoclonal antibody characterization using functionalized porous membranes. Sequential adsorption of poly (styrene sulfonate) and pepsin in a porous nylon membrane forms a pepsin membrane reactor. Pepsin is inexpensive and catalyzes proteolysis in acidic solutions, which avoids the need to alkylate cysteine residues and limits antibody deamidation. Variation of the residence times (3 ms to 3 s) of antibody solutions in pepsin-containing membranes yields "bottom-up" (1-2 kDa) to 'middle-down' (5-15 kDa) peptides in less than 10 min. These peptic peptides cover the entire sequences of Herceptin and a WatersTM antibody. Compared with the performance of bottom-up (in-solution tryptic digestion) and top-down (intact protein fragmentation) analysis of an antibody light chain, middle-down (in-membrane peptic digestion) analysis gives the highest bond cleavage (99%). In-membrane digestion also facilitates detection of PTMs such as oxidation, deamidation, N-terminal pyroglutamic acid formation and glycosylation. Recently developed protease-containing spin membranes provide an excellent platform for rapid, membrane-based protein digestion prior to ultrahigh-resolution Orbitrap MS analysis. Centrifugation of 100-200 æL of pretreated protein solutions through the pepsin- or trypsin-containing membranes takes less than 1 min and gives nearly 100% coverage of the protein sequences in subsequent direct infusion MS analysis of digests of apomyoglobin and four commercial monoclonal antibodies (Herceptin, Avastin, Rituxan and Vectibix). MS analysis of peptic and tryptic peptides also reveals mAb PTMs such as N-terminal pyroglutamate formation, C-terminal Lysine clipping and glycosylation. Liquid chromatography coupled to tandem mass spectrometry analysis of tryptic spin digests and subsequent MaxQuant data searching show 100% sequence coverage of all four antibody light chains, and 75.1%-98.4% coverage of the heavy chains. Compared to in-solution tryptic digestion of mAbs, spin digestion yields higher sequence coverage and a larger number of unique peptides. In-membrane digestion also facilitates protein sequence comparison. Rapid peptic in-membrane digestion of two antibodies with direct infusion MS analysis accurately reveals the antibody modification site in less than 1 h. Overall, membrane-based protein digestion uses minimal sample preparation time and yields high peptide and sequence coverages for identification of protein PTMs."--Page ii-iii.
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Title: Linguistic strategies of entrepreneurial firms and financial resource acquisition
Creator: Pan, Lingling
Date: 2018
Collection: Electronic Theses & Dissertations
Description: "Resource acquisition from external investors is critical for the survival of entrepreneurial firms. Prior research indicated that an entrepreneurial firm's strategic use of language in public communication can enhance the firm's opportunity to obtain external funding. In this dissertation, I extend this line of research by focusing on the linguistic characteristics of an entrepreneurial firm's communication. Specifically, I focus on whether and how language vividness, a critical lexical...
Show more"Resource acquisition from external investors is critical for the survival of entrepreneurial firms. Prior research indicated that an entrepreneurial firm's strategic use of language in public communication can enhance the firm's opportunity to obtain external funding. In this dissertation, I extend this line of research by focusing on the linguistic characteristics of an entrepreneurial firm's communication. Specifically, I focus on whether and how language vividness, a critical lexical characteristic of an entrepreneurial firm's public communication, influences the firm's financial resource acquisition performance. Using entrepreneurial firms' IPO events as the study context, I examine the association between the level of language vividness of a firm's IPO prospectuses and its IPO performance. I argue that, in general, an entrepreneurial firm will have greater IPO success if its prospectus shows high usage of concrete and imagery words--the two primary dimensions of vivid language. Furthermore, I argue that the effects of vivid language are contingent on three factors: 1) the similarity of the language strategy the firm employs relative to the industry it is operating in; 2) the hotness of the IPO market the firm belongs; and 3) the specific content domain (section) in the IPO prospectus. Examining a sample of 679 IPO firms, I find that language concreteness and language imagery are positively associated with firm's IPO outcome. In addition, the hotness of IPO market that a firm belongs moderates the relationship between the firm's level of language imagery and IPO outcome."--Page ii.
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Title: GEOBIA for post-fire identification of jack pine saplings
Creator: Bomber, Michael Jeffrey
Date: 2018
Collection: Electronic Theses & Dissertations
Description: Wildfire is a natural and necessary process which causes both devastation and regeneration to forested landscapes. One such event, the Duck Lake Fire, occurred in the Upper Peninsula (UP) of Michigan in the United States in 2012. The burn area is overseen by the Michigan Department of Natural Resources (MDNR) and encompasses approximately 8900 ha (21,000 acres) near the mouth of the Two Hearted River on the south shore of Lake Superior. After the fire, replanting by the MDNR and natural...
Show moreWildfire is a natural and necessary process which causes both devastation and regeneration to forested landscapes. One such event, the Duck Lake Fire, occurred in the Upper Peninsula (UP) of Michigan in the United States in 2012. The burn area is overseen by the Michigan Department of Natural Resources (MDNR) and encompasses approximately 8900 ha (21,000 acres) near the mouth of the Two Hearted River on the south shore of Lake Superior. After the fire, replanting by the MDNR and natural regeneration has taken place. Unmanned Aerial Systems (UAS) imagery of ten 1-ha study plots were collected via a MicaSense Red Edge camera simultaneously capturing images in the Red, Green, Blue, Red Edge and NIR bands. Images were collected at 60 meters altitude with platform velocity of 6 m/s. Geographic Object-Based Image Analysis (GEOBIA) in eCognnition Developer was conducted to assess the regrowth of jack pine in the Duck Lake forest and answer three questions: What is the level of accuracy that can be achieved via GEOBIA for detecting young jack pine saplings? How does the use of the Red Edge (RE) spectral band affect image classification accuracy? How does seasonal change affect the accuracy that can is achieved by the UAS and GEOBIA method? GEOBIA classification accuracies ranged from 59.5-97.5% with the NIR-R band combination performing the best overall and RE performing the worst. An overall increase in accuracy was observed as the season progressed with the highest average accuracy in time three (T3) at 78.4% across all bands.
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Title: Where the rivers come together : reclaiming and re-imagining indigenous history, identity, and language in the city
Creator: Haviland, Adam
Date: 2017
Collection: Electronic Theses & Dissertations
Description: The movement and migration of Native Americans to urban areas is usually traced to the urbanization programs of the 1950s and 1960s. However, the recent scholarship of Coll Thrush (2007) and John Low (2016) highlight the long history of urban spaces as Indigenous spaces and the role Indigenous people and communities have played in their growth and development. Similarly, the discourse of language loss and revitalization, urban spaces, and Indigenous urban communities are seen as places or...
Show moreThe movement and migration of Native Americans to urban areas is usually traced to the urbanization programs of the 1950s and 1960s. However, the recent scholarship of Coll Thrush (2007) and John Low (2016) highlight the long history of urban spaces as Indigenous spaces and the role Indigenous people and communities have played in their growth and development. Similarly, the discourse of language loss and revitalization, urban spaces, and Indigenous urban communities are seen as places or endpoints of assimilation. Thus, language revitalization efforts and programs often focus on reservations as the primary domains where Indigenous languages and their speakers persist and thrive. Yet, despite settler colonial narratives of vanishing that erase Indigenous people and Indigenous languages from urban areas, cities have, and continue to be, important intersections of movement and migration and with deep historical roots where Indigenous languages persist and thrive as ideological markers of identity, belonging, and as spoken languages.This Research shows how Lansing, Michigan, Nkwejong (the place where the rivers come together) has a long history as an Indigenous intersection and space that challenges the local settler-colonial narratives of removal and erasure. Lansing has remained an Indigenous space through traditions of movement and migration that were driven by the auto industry and educational opportunities. Through these movements, Anishinabek from reservations in and around Manitoulin Island came here in the 1960s and 1970s who were fluent speakers ofAnishinaabemowin. Anishinabek from Canada and local Anishinabek, who had lost the language, created community and belonging through educational programs. These spaces have become focal points where community comes together and, for many individuals, are the primary spaces where language, culture, and identity are reclaimed and passed on. However, these are also spaces of tension where gender roles, language ideologies, and linguistic practices concerning language as an ideological marker of identity and its role as a communicative system are challenged and reimagined.Through interviews with community members and participant observation, I explore relationships to urban and reservation “homelands,” the importance of education as places where individuals develop relationships to their identities and culture, and the role that language, as both an ideological marker of identity and belonging and as a communicative system, play in their everyday lives and experiences. While most participants agreed that language was important to preserving identity and traditional knowledge, their relationships with their identities as urban and Indigenous, and their relationships to Indigenous language, highlight: (1) the need to reexamine language ideologies that link Language to “traditional culture and Knowledge” and the impacts these ideologies have on language revitalization. (2) The importance of urban areas as Indigenous homelands and places where Indigenous languages persist, and (3) the role of education as intersections and places of tension where multiple ideologies, identities, and ways of being Indigenous are expressed and reimagined.
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Title: Exploring the role of hydrologic residence time and chemistry in the processing of nitrate at the sediment-water interface
Creator: Hampton, Tyler Barbee
Date: 2018
Collection: Electronic Theses & Dissertations
Description: The concentrations of inorganic nitrogen, including nitrate (NO3-), are fundamental controls on the trophic state of aquatic ecosystems. Excess NO3- degrades drinking water quality, and therefore there is a need to understand processes that remove inorganic nitrogen. Controls on NO3- removal at the sediment-water interface (SWI) of aquatic ecosystems include both biogeochemical and hydrologic conditions, however the relative importance and interactions of these controls are poorly understood....
Show moreThe concentrations of inorganic nitrogen, including nitrate (NO3-), are fundamental controls on the trophic state of aquatic ecosystems. Excess NO3- degrades drinking water quality, and therefore there is a need to understand processes that remove inorganic nitrogen. Controls on NO3- removal at the sediment-water interface (SWI) of aquatic ecosystems include both biogeochemical and hydrologic conditions, however the relative importance and interactions of these controls are poorly understood. This thesis explores these controls on NO3- removal using a series of in-situ experiments involving both biogeochemical and hydrologic manipulations of the SWI in both lake and stream settings. Specifically, manipulative experiments altered dissolved organic carbon (DOC) and NO3- concentrations, as well as physical hydrologic residence times. The fate of NO3- in these manipulation experiments was traced by pairing isotopically labeled 15N-NO3- tracer experiments with controlled variable-head infiltrometer rings to isolate the sediment-water system and control the hydrology of the SWI. With these experiments, I was able to isolate biogeochemical versus hydrologic controls on rates of NO3- removal and denitrification rates. I found that increasing NO3- and DOC concentrations increased NO3- removal and denitrification rates in the SWI, but that increases in physical residence time had a stronger effect on increasing NO3- removal and denitrification rates, especially under conditions where DOC and NO3- availability were not limiting.
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Title: Computational study of strongly coupled charged particle systems
Creator: Dharuman, Gautham
Date: 2018
Collection: Electronic Theses & Dissertations
Description: Exciting experiments in ultracold neutral plasmas, laser-matter interaction, charged particle stopping, mixing under extreme conditions etc., at academic facilities or at even larger facilities such as the National Ignition Facility, Z machine or the Linac Coherent Light Source, have necessitated the need for models that can simulate these systems at large length- and time-scales. This thesis summarizes my research work, falling within the category of computational plasma physics, aimed at...
Show moreExciting experiments in ultracold neutral plasmas, laser-matter interaction, charged particle stopping, mixing under extreme conditions etc., at academic facilities or at even larger facilities such as the National Ignition Facility, Z machine or the Linac Coherent Light Source, have necessitated the need for models that can simulate these systems at large length- and time-scales. This thesis summarizes my research work, falling within the category of computational plasma physics, aimed at three aspects: effective quantum potentials based method for non-equilibrium quantum electron dynamics at scale, efficient force calculation method for molecular dynamics simulation with screened Coulomb interactions, and an avenue based on compressed gases for creation of laboratory-scale tunable strongly coupled plasmas as a platform for understanding large-scale experiments. Effective classical dynamics provide a potentially powerful avenue for modeling large-scale dynamical quantum systems. We have examined the accuracy of a Hamiltonian-based approach that employs effective momentum-dependent potentials (MDPs) within a molecular-dynamics framework through studies of atomic ground states, excited states, ionization energies and scattering properties of continuum states. Working exclusively with the Kirschbaum-Wilets (KW) formulation with empirical MDPs [C. L. Kirschbaum and L. Wilets, PRA 21, 834 (1980)], leads to very accurate ground-state energies for several elements (e.g., N, F, Ne, Al, S, Ar and Ca) relative to Hartree-Fock values. The KW MDP parameters obtained are found to be correlated, thereby revealing some degree of transferability in the empirically determined parameters. We have studied excited-state orbits of electron-ion pair to analyze the consequences of the MDP on the classical Coulomb catastrophe. From the ground-state energies, we find that the experimental first- and second-ionization energies are fairly well predicted. Finally, electron-ion scattering was examined by comparing the predicted momentum transfer cross section to a semi-classical phase-shift calculation; optimizing the MDP parameters for the scattering process yielded rather poor results, suggesting a limitation of the use of the KW MDPs for plasmas. Efficient force calculation methods are needed for molecular dynamics simulation with medium-range interactions. Such interactions occur in a wide range of systems, including charged-particle systems with varying screening lengths. We generalize the Ewald method to charged systems described by interactions involving an arbitrary dielectric response function. We provide an error estimate and optimize the generalization to find the break-even parameters that separate a neighbor list-only algorithm from the particle-particle particle-mesh (PPPM) algorithm. We examine the implications of different choices of the screening length for the computational cost of computing the dynamic structure factor. We then use our new method in molecular dynamics simulations to compute the dynamic structure factor for a model plasma system and examine the wave-dispersion properties of this system. Laboratory-scale non-ideal plasmas with controllable properties over a wide range of densities below solid density are needed for understanding large-scale plasma experiments. Based on a suite of molecular dynamics simulations, we propose a general paradigm for producing such controllable non-ideal plasmas. We simulated the formation of non-equilibrium plasmas from photoionized, cool gases that are spatially precorrelated through neutral-neutral interactions that are important at moderate to high pressures. We examined the plasma-formation process over orders-of-magnitude variations in the initial gas pressure to characterize variations in several physical properties, including Coulomb collisional rates, partial pressures, screening strengths, continuum lowering, interspecies Coulomb coupling, electron degeneracy and ionization states. We find that variations in the initial gas pressure lead to controllable variations in a wide range of plasma properties, including the equation of state, collisional processes, atomic processes and basic plasma properties (coupling, screening and degeneracy). This paradigm has significant advantages over solid-density experiments because the collisional, collective and recombination timescales are reduced by a factor of 3 to 10, potentially broadening the efficacy of diagnostics. The paradigm also has advantages over ultracold plasma experiments because the trapping and cooling phases are avoided.
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Title: Connecting the wrong dots : can thalamo-cortical dysconnectivity explain altered corollary discharge in schizophrenia?
Creator: Yao, Beier
Date: 2018
Collection: Electronic Theses & Dissertations
Description: Corollary discharge (CD) signals are "copies" of motor signals sent to sensory areas to predict the impending input. Because they are used to distinguish actions generated by oneself versus external forces, altered CD has been hypothesized to result in the commonly-observed agency disturbances in schizophrenia patients (SZP). Behavioral evidence for altered CD in SZP has been observed in multiple sensorimotor domains, including the oculomotor system; however, its exact neural underpinning is...
Show moreCorollary discharge (CD) signals are "copies" of motor signals sent to sensory areas to predict the impending input. Because they are used to distinguish actions generated by oneself versus external forces, altered CD has been hypothesized to result in the commonly-observed agency disturbances in schizophrenia patients (SZP). Behavioral evidence for altered CD in SZP has been observed in multiple sensorimotor domains, including the oculomotor system; however, its exact neural underpinning is unknown. One oculomotor CD pathway identified in primates projects from motor neurons in the superior colliculus (SC) to visual neurons in the frontal eye fields (FEF) via the mediodorsal thalamus (MDT). The current study aimed to examine the structural connectivity of MDT-FEF pathway in SZP and whether it relates to oculomotor CD abnormalities. Twenty-four SZP and 22 healthy controls (HC) underwent diffusion tensor imaging (DTI), and a large subset of those individuals also performed the blanking task, an eye movement task that measures the influence of CD on visual perception. Probabilistic tractography was used to identify white matter tracts connecting FEF and MDT. Microstructural integrity of these tracts was compared across groups and correlated with behavioral indices of oculomotor CD from the blanking task and symptom severity. We found that SZP had compromised microstructural integrity in MDT-FEF pathway. This hypoconnectivity was correlated with both impaired oculomotor CD signals and more severe positive symptoms in SZP. These data suggest that the MDT-FEF pathway may serve an important role in transmitting oculomotor CD signals, which in turn may relate to positive symptom manifestation in SZP.
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Title: Maize production intensification in Kenya
Creator: Olwande, John Otieno
Date: 2018
Collection: Electronic Theses & Dissertations
Description: Soil infertility is one of the major problems contributing to low and stagnated agricultural productivity in sub-Saharan Africa. In Kenya, this problem is manifested in maize where yields have remained low and stagnated over time despite increased use of inorganic fertilizers and improved seed varieties. More effective alternatives and/or complimentary actions to address this problem thus remains germane. This dissertation contributes to that endeavor through two broad objectives: to generate...
Show moreSoil infertility is one of the major problems contributing to low and stagnated agricultural productivity in sub-Saharan Africa. In Kenya, this problem is manifested in maize where yields have remained low and stagnated over time despite increased use of inorganic fertilizers and improved seed varieties. More effective alternatives and/or complimentary actions to address this problem thus remains germane. This dissertation contributes to that endeavor through two broad objectives: to generate evidence that can support decisions to address the problem of low agricultural productivity in general and of maize in particular in Kenya; and to contribute to the body of knowledge about agricultural intensification in sub-Saharan Africa.The first essay uses household panel survey data from rural Kenya covering a period of 13 years (1997 – 2010) to examine trends and patterns in land and labor productivity of maize, measured as net returns to land and to family labor. Results show declining landholdings and farm sizes but maize occupied over one-half of cultivated land. Land productivity declined by 42% for households with at least 10 acres and by 33% in the most important maize producing regions. Labor productivity increased in areas with smaller landholdings and higher population density because of increase in land productivity, and declined or only marginally increased in areas with larger landholdings and lower population density because of a decline in land productivity. These results demonstrate that increasing maize production and returns to family labor in Kenya will rely on improving yields especially in the major maize growing areas where this has declined.The second essay uses data on maize production in five major maize growing counties in Kenya to compare maize farmers’ perceived soil fertility to measured soil fertility. It also investigates the influence of farmers’ perceptions of soil fertility on their adoption (use) of soil fertility management practices. Results show little agreement between farmers’ perceived and measured soil fertility, and farmers mostly judge the fertility status of soil by crop performance. Farmers apply management practices that may not match the fertility needs of soil on their plots, exemplified by the persistent application of an acidifying fertilizer (diammonium phosphate (DAP)) and low application of organic soil amendments even on plots with soils that are acidic and deficient in organic carbon. Farmers on average are more likely to apply inorganic fertilizer to plots they perceive to be infertile, and they treat manure or compost and inorganic fertilizers as serving substitute roles in soil fertility. These results suggest policy and extension information gaps regarding soil fertility management.The third essay uses the same dataset as in the second essay together with rainfall data to estimate technical efficiency of maize farmers and the effect of farmers’ soil fertility perception on technical efficiency. It also demonstrates the importance of including environmental production conditions and agronomic practices in agricultural productivity and efficiency analysis. Average technical efficiency level is 0.75 and 0.70, respectively, with and without environmental variables and agronomic practices in the model, indicating that scope for increasing maize yield through better management of inputs exits and that omission of environmental variables and agronomic practices underestimates technical efficiency. Farmers’ perception of soil fertility and the consistency of their perception with measured soil fertility both have significant effects on technical efficiency, underscoring the importance of information that can enhance farmers’ accurate understanding about soil fertility conditions on their farms to help them make better production decisions.
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Title: Feasibility and application of a CuxO-based memristor for sensing oxygen and other gases
Creator: Nyenke, Chinwe Pamela
Date: 2017
Collection: Electronic Theses & Dissertations
Description: This dissertation introduces the design, fabrication, and application of acopper-oxide-based memristor for the passive sensing of oxygen and other gases.The device design was as follows: Deposition of copper (Cu) bottom electrodes,(oxygen) vacancy-rich copper oxide (CuxO) switching layers, and tungsten (W) topelectrodes in a crossbar array structure. The CuxO layer was deposited via reactivesputtering of a Cu target with an argon-oxygen (Ar/O2) mixture. A portion of thislayer was extended...
Show moreThis dissertation introduces the design, fabrication, and application of acopper-oxide-based memristor for the passive sensing of oxygen and other gases.The device design was as follows: Deposition of copper (Cu) bottom electrodes,(oxygen) vacancy-rich copper oxide (CuxO) switching layers, and tungsten (W) topelectrodes in a crossbar array structure. The CuxO layer was deposited via reactivesputtering of a Cu target with an argon-oxygen (Ar/O2) mixture. A portion of thislayer was extended from each array cell to be exposed for sensing. Memristivedevices of different switching layer thicknesses were initially explored forirreversible sensing of oxygen in ambient air. Results of this first experimentdemonstrated an increase in resistance states upon prolonged exposure toambient air. For the second experiment, memristive devices were fabricated withsub-micron holes that were etched into the W top electrode to better reveal theswitching layer surface. The devices were also subjected to ambient oxygen at 180deg C to induce passive sensing in minutes. Resistance results were consistentwith the first experiment but also revealed a dependence on the surface area ofthe exposed oxide. Finally, memristive devices were investigated in a thirdexperiment for reversible sensing of an oxidizing gas and reducing gas at roomtemperature. This time, changes were not only observed in resistance but also inhysteresis (current versus voltage) depending on the type of gas introduced.Overall, this work demonstrates a step towards the use of the memristor as a gassensor, which we have named “memsensors”, by taking advantage of the device’sability to memorize (or record) historical information.
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Title: Preservice teachers' intention to teach media and information literacy in their future classroom : an application of the theory of planned behavior
Creator: Gretter, Sarah
Date: 2017
Collection: Electronic Theses & Dissertations
Description: "This dissertation is a multi-phase study looking at preservice teachers' intention to teach Media & Information Literacy in their future classroom. Each of the three studies presented in this dissertation answered a specific question: 1) What do preservice teachers think about teaching MIL? 2) What predicts preservice teachers' intention to teach MIL? and 3) How can we support preservice teachers' intention to teach MIL? The first paper in this dissertation reported on an elicitation study...
Show more"This dissertation is a multi-phase study looking at preservice teachers' intention to teach Media & Information Literacy in their future classroom. Each of the three studies presented in this dissertation answered a specific question: 1) What do preservice teachers think about teaching MIL? 2) What predicts preservice teachers' intention to teach MIL? and 3) How can we support preservice teachers' intention to teach MIL? The first paper in this dissertation reported on an elicitation study conducted with focus groups of preservice teachers to understand, from their perspectives, the factors that would either impede or facilitate the teaching of MIL in their future classroom. The second paper described the design, validation, and results of a survey based on these factors. The third paper reported on an online module with reflective exercises designed around the results gathered in the aforementioned survey. Each paper describes the findings that emerged from its study, followed by implications for research and practice, along with questions for the field of Media & Information Literacy education"--Page ii.
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Title: Role of a alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor on methylmercury-induced calcium dysregulation on motor neurons
Creator: Colón-Rodríguez, Alexandra
Date: 2017
Collection: Electronic Theses & Dissertations
Description: Methylmercury (MeHg) is a persistent environmental neurotoxicant to which humans are exposed mainly through the consumption of fish. MeHg leads to neuronal cell death in acute or chronic exposure and its mechanism of toxicity is not yet understood. Due to its high prevalence in the environment and its mechanism of toxicity MeHg has been considered a possible contributor to the development of Amyotrophic Lateral Sclerosis (ALS). Alterations in glutamate reuptake and Ca2+ regulation in ALS and...
Show moreMethylmercury (MeHg) is a persistent environmental neurotoxicant to which humans are exposed mainly through the consumption of fish. MeHg leads to neuronal cell death in acute or chronic exposure and its mechanism of toxicity is not yet understood. Due to its high prevalence in the environment and its mechanism of toxicity MeHg has been considered a possible contributor to the development of Amyotrophic Lateral Sclerosis (ALS). Alterations in glutamate reuptake and Ca2+ regulation in ALS and after MeHg exposures have been well documented. Most importantly, MeHg-induced alterations in intracellular Ca2+ ([Ca2+]i) in motor neurons lead to early onset ALS-like phenotype in the superoxide dismutase 1 (SOD1-G93A) mouse, a mouse model genetically susceptible to ALS. One of the ion channels that contribute to the alterations in [Ca2+]i observed in ALS and after MeHg exposure is the ionotropic glutamate receptor α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA). My research has focused on characterizing the effects of MeHg on motor neurons in vitro. I used two cell lines: a mouse motor neuron hybrid cell line NSC34 and an induced pluripotent stem cell derived-motor neuron (hiPSC-MN) cell line of human origin. I investigated MeHg toxicity in these cell types and on AMPA receptors in order to understand the role these ion channels play in the observed alterations in [Ca2+]i. Results from the studies in this dissertation demonstrate that MeHg exposure in vivo or in vitro lead to alterations in the AMPA receptor and the RNA editing enzyme ADAR2 gene expression. Also, that hiPSC-MNs are more susceptible than NSC34 cells to MeHg toxicity observed as an earlier concentration dependent cell death. I also identified that MeHg induces a bi-phasic increase in [Ca2+]i in hiPSC-MNs and Ca2+ permeable AMPA receptors are mediating those increases. Taken together these results suggest a potential role of the AMPA receptors in MeHg-induced toxicity in MNs. These findings contribute to the understanding of MeHg-induced toxicity in motor neurons and provide a platform for ongoing studies in our lab which are focused on identifying the underlying mechanisms by which MeHg is contributing to the accelerated onset of ALS-like phenotype.
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