The democracy of Walt Whitman as exemplified in democratic vistas

Thesis (M.A.)--Boston University, 1948. This item was digitized by the Internet Archive

CONCENTRATION ISSUES IN THE U.S. BEEF SUBSECTOR

Industrial Organization, Livestock Production/Industries,

Accretion variability in young, low-mass stellar systems

Through the study of accretion onto the young, low-mass stars known as T Tauri Stars (TTS), we can better understand the formation of our solar system. Gas is funneled along stellar magnetic field lines into magnetospheric accretion columns where it reaches free-fall velocities and shocks at the stellar surface, generating emission that carries information about the inner regions of the protoplanetary disk. Accretion is a variable process, with characteristic timescales ranging from minutes to years. In this dissertation, I use simulations, models, and observations to provide insight into the driving forces of mass accretion rate variability on timescales of minutes to weeks and the structure of the inner disk. Using hydrodynamic simulations, I find that steady-state, transonic accretion occurs naturally in the absence of any other source of variability. If the density in the inner disk varies smoothly in time with roughly day-long time-scales (e.g., due to turbulence), traveling shocks develop within the accretion column, which lead to rapid increases in the accretion luminosity followed by slower declines. I present the largest Hubble Space Telescope (HST) spectral variability study of TTS to date. I infer mass accretion rates and accretion column surface coverage using newly updated accretion shock models. I find typical changes in the mass accretion rate of order 10% and moderate changes in the surface coverage for most objects in the sample on week timescales. Individual peculiar epochs are further discussed. I find that the inner disk is inhomogeneous and that dust may survive near the magnetic truncation radius. Next, I link 2-minute cadence light curves from the Transiting Exoplanet Survey Satellite (TESS) to accretion using ground-based U-band photometry. Additional HST observations for one target enable more detailed connections between TESS light curves and accretion. I also use the TESS light curves to identify rotation periods and patterns of quasi-periodicity. Finally, I connect hydrodynamic simulations, accretion shock models, and stellar rotation to predict signatures of a turbulent inner disk. I generate light curves from these models to make comparisons to previous month-long photometric monitoring surveys of TTS using metrics of light curve symmetry and periodicity

Inhibition of protein geranylgeranylation induces apoptosis in synovial fibroblasts

Statins, competitive inhibitors of hydroxymethylglutaryl-CoA reductase, have recently been shown to have a therapeutic effect in rheumatoid arthritis (RA). In RA, synovial fibroblasts in the synovial lining, are believed to be particularly important in the pathogenesis of disease because they recruit leukocytes into the synovium and secrete angiogenesis-promoting molecules and proteases that degrade extracellular matrix. In this study, we show a marked reduction in RA synovial fibroblast survival through the induction of apoptosis when the cells were cultured with statins. Simvastatin was more effective in RA synovial fibroblasts than atorvastatin, and both statins were more potent on tumor necrosis factor-α-induced cells. In contrast, in osteoarthritis synovial fibroblasts, neither the statin nor the activation state of the cell contributed to the efficacy of apoptosis induction. Viability of statin-treated cells could be rescued by geranylgeraniol but not by farnesol, suggesting a requirement for a geranylgeranylated protein for synovial fibroblast survival. Phase partitioning experiments confirmed that in the presence of statin, geranylgeranylated proteins are redistributed to the cytoplasm. siRNA experiments demonstrated a role for Rac1 in synovial fibroblast survival. Western blotting showed that the activated phosphorylated form of Akt, a protein previously implicated in RA synovial fibroblast survival, was decreased by about 75%. The results presented in this study lend further support to the importance of elevated pAkt levels to RA synovial fibroblast survival and suggest that statins might have a beneficial role in reducing the aberrant pAkt levels in patients with RA. The results may also partly explain the therapeutic effect of atorvastatin in patients with RA

Democratic Teacher Preparation and Praxis: Creating Active, Reflective Educators (CARE)

This qualitative study investigates the ability of teachers that have completed their clinical experience—i.e., teacher preparation—in a school grounded in Deweyan theory to maintain a democratic practice. As such, the study focused on educators that were graduates of a school-university partnership program, known as CARE—Creating Active, Reflective Educators. Data were collected to address the following research question: “To what extent can former CARE students practice democratic education in their current public-school teaching environment?” Interviews conducted with current school teachers and leaders that were former CARE program students. Responses were audio-recorded and transcribed, then coded and organized into thematic units to report findings

Exploring Model Misspecification in Statistical Finite Elements via Shallow Water Equations

The abundance of observed data in recent years has increased the number of statistical augmentations to complex models across science and engineering. By augmentation we mean coherent statistical methods that incorporate measurements upon arrival and adjust the model accordingly. However, in this research area methodological developments tend to be central, with important assessments of model fidelity often taking second place. Recently, the statistical finite element method (statFEM) has been posited as a potential solution to the problem of model misspecification when the data are believed to be generated from an underlying partial differential equation system. Bayes nonlinear filtering permits data driven finite element discretised solutions that are updated to give a posterior distribution which quantifies the uncertainty over model solutions. The statFEM has shown great promise in systems subject to mild misspecification but its ability to handle scenarios of severe model misspecification has not yet been presented. In this paper we fill this gap, studying statFEM in the context of shallow water equations chosen for their oceanographic relevance. By deliberately misspecifying the governing equations, via linearisation, viscosity, and bathymetry, we systematically analyse misspecification through studying how the resultant approximate posterior distribution is affected, under additional regimes of decreasing spatiotemporal observational frequency. Results show that statFEM performs well with reasonable accuracy, as measured by theoretically sound proper scoring rules.Comment: 16 pages, 9 figures, 4 tables, submitted versio