Exploring tensions, identities, and equitable science assessment practices in undergraduate agroecology education

National reform documents suggest that changing pedagogical and assessment practices in college science courses are necessary but challenging steps to help support the formation of science identities. This dissertation is a collection of three separate research manuscripts that examined the challenges and affordances of designing and enacting curriculum and assessment practices in an upper-level agroecology course titled, Advanced Practices of Sustainable Agriculture. All three studies integrate theoretical lenses of situated learning, communities of practice, and identity and agency in cultural worlds to support and describe the process of science identity formation. Five instructors and thirteen students participated in the research process. During the fifteen-week semester in the Fall of 2013, pre/post narrative interviews, weekly instructor planning sessions, weekly classes, student assignments, and course artifacts were collected. Interviews were transcribed and remaining data were then analyzed using NVivo10 software and a variety of qualitative methods. The first research manuscript employs case study methodology to explore the sociocultural tensions within the classroom community of practice. Two ethnographic vignettes were used to describe the nature of four interconnected sociocultural tensions: (1) individual tensions, (2) community tensions, (3) local/global tensions, and (4) local tensions. Attending to these tensions that are inherent in student-centered, democratic learning is central to the wicked problem of agroecology education. The second manuscript aims to expand the purposes of Science, Technology, Engineering, and Math (STEM) education reform to accommodate disciplines like agroecology that is framed as a Feminist - STEM (F-STEM) discipline. Previous research has focused on the science identity gap that exists for women and other non-dominant groups. Despite academic gains in science courses, women and underrepresented learners might still feel as if science is not for them. Using the voices of three women in the course, the study uncovered aspects of Equitable Science Assessment Practices (ESAP) that support the formation of F-STEM Identities. Inspired by the stories and experiences of the three participants, four features of ESAP were characterized using iterative qualitative analysis and poetic representation: (1) allowing flexibility, (2) sharing authority, (3) laminating voices, and (4) scaffolding social justice. These interdependent features of ESAP that focus on identity formation can provide course design principles and present new opportunities to merge critical feminist studies of science education and equitable assessment. The third manuscript integrated the mapping and tracing of rhizomes with the practice of reflexivity in qualitative research to describe a process of becoming Bermuda Grass, a rhizome encountered and mimicked by the researcher. The study was initiated when a student participant expressed an identity of non-participation in the course. The article provides a narrative account of applying aspects of rhizome theory and reflexivity to gain new meaning and insight to support learners in an agroecology course. These three manuscripts focus on different grain sizes and help make connections between local contexts and global issues of environmental and social justice. This research contributes a new dimension to a framework for the political ecology of education focused on supporting learner identity transformation through classroom assessment practices

Quantifying Yeast Chronological Life Span by Outgrowth of Aged Cells

The budding yeast Saccharomyces cerevisiae has proven to be an important model organism in the field of aging research 1. The replicative and chronological life spans are two established paradigms used to study aging in yeast. Replicative aging is defined as the number of daughter cells a single yeast mother cell produces before senescence; chronological aging is defined by the length of time cells can survive in a non-dividing, quiescence-like state 2. We have developed a high-throughput method for quantitative measurement of chronological life span. This method involves aging the cells in a defined medium under agitation and at constant temperature. At each age-point, a sub-population of cells is removed from the aging culture and inoculated into rich growth medium. A high-resolution growth curve is then obtained for this sub-population of aged cells using a Bioscreen C MBR machine. An algorithm is then applied to determine the relative proportion of viable cells in each sub-population based on the growth kinetics at each age-point. This method requires substantially less time and resources compared to other chronological lifespan assays while maintaining reproducibility and precision. The high-throughput nature of this assay should allow for large-scale genetic and chemical screens to identify novel longevity modifiers for further testing in more complex organisms

Variable Spin-down in the Soft Gamma Repeater SGR 1900+14 and Correlations with Burst Activity

We have analyzed Rossi X-ray Timing Explorer Proportional Counter Array observations of the pulsed emission from SGR 1900+14 during September 1996, June - October 1998, and early 1999. Using these measurements and results reported elsewhere, we construct a period history of this source for 2.5 years. We find significant deviations from a steady spin-down trend during quiescence and the burst active interval. Burst and Transient Source Experiment observations of the burst emission are presented and correlations between the burst activity and spin-down rate of SGR 1900+14 are discussed. We find an 80 day interval during the summer of 1998 when the average spin-down rate is larger than the rate elsewhere by a factor ~ 2.3. This enhanced spin-down may be the result of a discontinuous spin-down event or ``braking glitch'' at the time of the giant flare on 27 August 1998. Furthermore, we find a large discrepancy between the pulsar period and average spin-down rate in X-rays as compared to radio observations for December 1998 and January 1999.Comment: 6 pages, 2 figures, submitted to ApJ Letter

Socio-scientific Issues based Teaching and Learning: Hydrofracturing as an Illustrative context of a Framework for Implementation and Research

Global citizens are constantly immersed in issues like hydraulic fracturing or "hydrofracturing" that rely upon scientific knowledge and the ability to negotiate multiple forms of evidence and reasoning to make informed decisions. Historically, Environmental Education and Science Education have been well positioned to provide learning experiences that support the development of important skills like Discourse that are requisite for full participation in our worldwide community. In this article, we explore the confluence of environmental education, science education, and the emergence of an empirical model for socio-scientific Issues (SSI) based teaching and learning. While environmental education and science education have distinct differences, there are significant overlaps in content and process. The emergence of SSI from the field of science education presents opportunities to drive environmental education, and a new framework for guiding SSI based teaching and learning can be useful in terms of informing focus, structure and processes for teaching through issues. Using hydrofracturing as a sample issue, we demonstrate how this recently developed SSI framework can be applied to create learning environments that support development of critical Discourse practices and further the goals of science and environmental education. The core aspects of the framework are 1) design elements, 2) learner experiences, and 3) teacher attributes. We elaborate each of these aspects and demonstrate how to reposition science content and the roles of students and teachers to engage in the issue of hydrofracturing. The SSI framework also highlights the importance of a safe classroom community and an awareness of the broader geo-political context when practicing SSI based teaching and learning.  This work provides a theoretical and practical basis to drive the fields of science and environmental education towards research and teaching that promote engaged global citizenship and social justice

Fluorescence-detected magnetic field effects on radical pair reactions from femtolitre volumes

We show that the effects of applied magnetic fields on radical pair reactions can be sensitively measured from sample volumes as low as ~100 femtolitres using total internal reflection fluorescence microscopy. Development of a fluorescence-based microscope method is likely to be a key step in further miniaturisation that will allow detection of magnetic field effects on single molecules

Two-sided combinatorial volume bounds for non-obtuse hyperbolic polyhedra

We give a method for computing upper and lower bounds for the volume of a non-obtuse hyperbolic polyhedron in terms of the combinatorics of the 1-skeleton. We introduce an algorithm that detects the geometric decomposition of good 3-orbifolds with planar singular locus and underlying manifold the 3-sphere. The volume bounds follow from techniques related to the proof of Thurston's Orbifold Theorem, Schl\"afli's formula, and previous results of the author giving volume bounds for right-angled hyperbolic polyhedra.Comment: 36 pages, 19 figure

A Hubble Space Telescope Study of Lyman Limit Systems: Census and Evolution

We present a survey for optically thick Lyman limit absorbers at z<2.6 using archival Hubble Space Telescope observations with the Faint Object Spectrograph and Space Telescope Imaging Spectrograph. We identify 206 Lyman limit systems (LLSs) increasing the number of catalogued LLSs at z<2.6 by a factor of ~10. We compile a statistical sample of 50 tau_LLS > 2 LLSs drawn from 249 QSO sight lines that avoid known targeting biases. The incidence of such LLSs per unit redshift, l(z)=dn/dz, at these redshifts is well described by a single power law, l(z) = C1 (1+z)^gamma, with gamma=1.33 +/- 0.61 at z<2.6, or with gamma=1.83 +/- 0.21 over the redshift range 0.2 < z < 4.9. The incidence of LLSs per absorption distance, l(X), decreases by a factor of ~1.5 over the ~0.6 Gyr from z=4.9 to 3.5; l(X) evolves much more slowly at low redshifts, decreasing by a similar factor over the ~8 Gyr from z=2.6 to 0.25. We show that the column density distribution function, f(N(HI)), at low redshift is not well fitted by a single power law index (f(N(HI)) = C2 N(HI)^(-beta)) over the column density range 13 17.2. While low and high redshift f(N(HI)) distributions are consistent for log N(HI)>19.0, there is some evidence that f(N(HI)) evolves with z for log N(HI) < 17.7, possibly due to the evolution of the UV background and galactic feedback. Assuming LLSs are associated with individual galaxies, we show that the physical cross section of the optically thick envelopes of galaxies decreased by a factor of ~9 from z~5 to 2 and has remained relatively constant since that time. We argue that a significant fraction of the observed population of LLSs arises in the circumgalactic gas of sub-L* galaxies.Comment: Accepted by Ap

Adrenalectomy for solitary adrenal metastasis from colorectal cancer: A case report

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