Impact of Intra-Articular Injection Use on Patient-Reported Outcomes Among Patients with Knee Osteoarthritis

Background: Knee osteoarthritis (OA) is the most common type of OA and is a major cause of pain and thus results in disability for daily activities among persons living in the community. OA currently has no cure. In addition to the conflicting recommendations from clinical guidelines, evidence about the extent to which long-term use of intra-articular injections improves patient outcomes is also lacking. Methods: Using data from the Osteoarthritis Initiative (OAI), marginal structural models (MSMs) applying inverse probability treatment weights (IPTW) were used to examine the effectiveness of intra-articular injections and changes in symptoms over time. The specific aims of this dissertation were to: 1) evaluate longitudinal use of intra-articular injections after treatment initiation among persons with radiographic knee OA; 2) quantify the extent to which intra-articular injection relieves symptoms among persons with radiographic knee OA; and 3) evaluate the performance of missing data techniques under the setting of MSMs. Results: Of those initiating injections, ~19% switched, ~21% continued injection type, and ~60% did not report any additional injections. For participants initiating corticosteroid (CO) injections, greater symptoms post-initial injection rather than changes in symptoms over time were associated with continued use compared to one-time use. Among participants with radiographic evidence of knee OA, initiating treatments with either CO or hyaluronic acid (HA) injections was not associated with reduced symptoms compared to non-users over two years. Compared to inverse probability weighting (IPW), missing data techniques such as multiple imputation (MI) produced less biased marginal causal effects (IPW: -2.33% to 15.74%; -1.88% to 4.24%). For most scenarios, estimates using MI had smaller mean square error (range: 0.013 to 0.024) than IPW (range: 0.027 to 0.22). Conclusions: Among participants with radiographic evidence of knee OA living in the community, the proportion of those switching injection use and one-time users was substantial after treatment initiation. In addition, initiating injection use was not associated with reduced symptoms over time. With respect to issues of missing data, using MI may confer an advantage over IPW in MSMs applications. The results of this work highlight the importance of using comparative effectiveness research with non-experimental data to study these commonly used injections and may help to understand the usefulness of these treatments for patients with knee OA

The [Ne III] Jet of DG Tau and its Ionization Scenarios

Forbidden neon emission from jets of low-mass young stars can be used to probe the underlying high-energy processes in these systems. We analyze spectra of the jet of DG Tau obtained with the Very Large Telescope/X-Shooter spectrograph in 2010. [Ne III] $\lambda$3869 is clearly detected in the innermost 3" microjet and the outer knot located at $\sim$6".5. The velocity structure of the inner microjet can be decomposed into the low-velocity component (LVC) at $\sim -70$ km/s and the high-velocity component (HVC) at $\sim -180$ km/s. Based on the observed [Ne III] flux and its spatial extent, we suggest the origins of the [Ne III] emission regions and their relation with known X-ray sources along the jet. The flares from the hard X-ray source close to the star may be the main ionization source of the innermost microjet. The fainter soft X-ray source at 0".2 from the star may provide sufficient heating to help to sustain the ionization fraction against the recombination in the flow. The outer knot may be reionized by shocks faster than 100 km/s such that [Ne III] emission reappears and that the soft X-ray emission at 5".5 is produced. Velocity decomposition of the archival Hubble Space Telescope spectra obtained in 1999 shows that the HVC had been faster, with a velocity centroid of $\sim -260$ km/s. Such a decrease in velocity may potentially be explained by the expansion of the stellar magnetosphere, changing the truncation radius and thus the launching speed of the jet. The energy released by magnetic reconnections during relaxation of the transition can heat the gas up to several tens of megakelvin and provide the explanation for on-source keV X-ray flares that ionize the neon microjet

Velocity-Resolved [Ne III] from X-Ray Irradiated Sz 102 Microjets

Neon emission lines are good indicators of high-excitation regions close to a young stellar system because of their high ionization potentials and large critical densities. We have discovered [Ne III]{\lambda}3869 emission from the microjets of Sz 102, a low-mass young star in Lupus III. Spectroastrometric analyses of two-dimensional [Ne III] spectra obtained from archival high-dispersion ($R\approx 33,000$) Very Large Telescope/UVES data suggest that the emission consists of two velocity components spatially separated by ~ 0."3, or a projected distance of ~ 60 AU. The stronger redshifted component is centered at ~ +21 km/s with a line width of ~ 140 km/s, and the weaker blueshifted component at ~ -90 km/s with a line width of ~ 190 km/s. The two components trace velocity centroids of the known microjets and show large line widths that extend across the systemic velocity, suggesting their potential origins in wide-angle winds that may eventually collimate into jets. Optical line ratios indicate that the microjets are hot ($T\lesssim1.6\times10^4$ K) and ionized ($n_e\gtrsim5.7\times10^4$ cm$^{-3}$). The blueshifted component has ~ 13% higher temperature and ~ 46% higher electron density than the redshifted counterpart, forming a system of asymmetric pair of jets. The detection of the [Ne III]{\lambda}3869 line with the distinct velocity profile suggests that the emission originates in flows that may have been strongly ionized by deeply embedded hard X-ray sources, most likely generated by magnetic processes. The discovery of [Ne III]{\lambda}3869 emission along with other optical forbidden lines from Sz 102 support the picture of wide-angle winds surrounding magnetic loops in the close vicinity of the young star. Future high sensitivity X-ray imaging and high angular-resolution optical spectroscopy may help confirm the picture proposed.Comment: 33 pages, 9 figures, 2 tables; accepted for publication in the ApJ (minor typo and reference list fixed

First-Year-Composition Writing Conferences as a Pathway for Becoming Graduate Teaching Assistants

Notwithstanding a veritable avalanche of scholarship in the past decades of the writing conference (WC), these studies tend to concentrate exclusively on the WC engagement done by secondary-school writing instructors or by senior faculty members and/or specialized instructors at the tertiary level. Little has been done on how first-year-composition graduate teaching assistants (FYC GTAs) establish their unique identity roles as GTAs. This current research study, through a qualitative case-study design, aims to further the understanding of two FYC GTAs’ identity formation at a large Midwestern university in the U.S. through the interconnectedness between WCs and institutional spaces. Methods included researcher observations, semi-structured interviews, and artifact collection. By qualitatively grounding the data analysis through the prism of an ontogenetic understanding (Prior, 2008; Prior & Shipka, 2003), this study reveals that the two FYC GTAs’ identities as GTAs are discursively morphed and negotiated through multilayered interpersonal interaction and institutional constraints and affordances. Through a discursive becoming and become, this research suggests that the rhetoric of treating FYC GTAs’ identity roles as a becoming trajectory might aid FYC GTAs, writing instructors, and writing-program administrators to orchestrate more pedagogically fruitful schemas and policies of WCs

Rashba Spin Interferometer

A spin interferometer utilizing the Rashba effect is proposed. The novel design is composed of a one-dimensional (1D) straight wire and a 1D half-ring. By calculating the norm of the superposed wave function, we derive analytical expressions to describe the spin interference spectrum as a function of the Rashba coupling strength. Presented spin interference results are identified to include (i) the quantum-mechanical 4pi rotation effect, (ii) geometric effect, and (iii) Shubnikov-de Haas-like beating effect.Comment: 3 pages, 3 figures, appears in the proceedings of the 10th Joint MMM/Intermag Conferenc