Developing and Validating Stealth Assessments for an Educational Game to Assess Young Dual Language Immersion Learners\u27 Reading Comprehension

The purpose of this multiple-paper dissertation is to design a digital game and stealth assessments within the game to assess young second language learners\u27 Chinese reading proficiency. In Chapter 2 (Paper 1), I describe the game designed for this dissertation and how it was implemented in a dual language immersion classroom. This study found that the digital game and in-class implementation led to significant vocabulary and reading comprehension gains. Further, seven types of support that students needed while playing the game were identified. In Chapter 3 (Paper 2), I describe how educational data mining approaches, and more specifically, how data-driven explorations, can provide insight into how players interact with the game and further how those interactions relate to proficiency and learning. In this study, I identify time on task and use of an in-game glossing tool as important indicators for learning. In addition, four subgroups of students were identified based on their gameplay styles. Finally, in Chapter 4 (Paper 3), I describe how stealth assessments were designed and validated within the game. This study found that the stealth assessments were significantly correlated with two external measures of reading comprehension

Investigating Linguistic, Literary, and Social Affordances of L2 Collaborative Reading

This exploratory study analyzes learner–learner interactions within a virtual environment when collaboratively reading Spanish poetry in a Hispanic literature course at the college level via an ecological theoretical perspective (van Lier, 2004). The goals of the study are (a) to present empirical data that illustrate the theoretical construct of affordance in a virtual, collaborative reading environment, and (b) to investigate the pedagogical ramifications of using a digital annotation tool to involve learners in collaborative reading. Three distinct types of affordances emerged in the data: linguistic, literary, and social affordances. Our findings indicate that the number of literary and social affordances outnumbered the linguistic affordances that emerged in students’ threaded discussions while collaboratively reading and annotating poems. In addition, the primary challenges for learners when engaging in collaborative reading included others’ comments impeding some students’ understanding of the text, and having to make one’s comments distinct from others’ comments to avoid being socially viewed as an inactive reader or student. From a pedagogical perspective, the primary benefits of incorporating collaborative reading in a second language poetry course involve the ability to establish a more open learning community and allowing students to carry out a closer reading of literary texts

Applying educational data mining to explore individual experiences in digital games

Research involving digital games and language learning is rapidly growing. One advantage of using digital games to support language learning is the ability to collect data on students learning in real time. In this study, we use educational data mining methods to explore the relationship between in-game data and elementary students’ Chinese language learning. Thirty-six students in the sixth grade played a digital game for eight 25-minute sessions as part of their Chinese Dual Language Immersion classroom instruction. We used classification and regression tree analyses and cluster analyses to explore how in- game indicators, such as battles, time spent reading a text, and the use of an in-game glossing tool are associated with language learning and change in affect. The results indicate that time on task and use of the glossing tool were the most important variables in determining language learning gains. We also identified four subgroups of gameplay styles. While there were no significant differences in learning or affective factors based on the subgroups, these gameplay styles allow for a more individualized approach to analyzing learning within digital environment

Second-Order Nonlinear Mixing of Two Modes in a Planar Photonic Crystal Microcavity

Polarization-resolved second-harmonic spectra are obtained from the resonant modes of a two-dimensional planar photonic crystal microcavity patterned in a free-standing InP slab. The photonic crystal microcavity is comprised of a single missing-hole defect in a hexagonal photonic crystal host formed with elliptically-shaped holes. The cavity supports two orthogonally-polarized resonant modes split by 60 wavenumbers. Sum-frequency data are reported from the nonlinear interaction of the two coherently excited modes, and the polarization dependence is explained in terms of the nonlinear susceptibility tensor of the host InP.Comment: 7 pages, 8 Postscript figures, to be presented at Photonics West Jan. 2

Characterization of subsurface media from locations up- and down-gradient of a uranium-contaminated aquifer.

The processing of sediment to accurately characterize the spatially-resolved depth profiles of geophysical and geochemical properties along with signatures of microbial density and activity remains a challenge especially in complex contaminated areas. This study processed cores from two sediment boreholes from background and contaminated core sediments and surrounding groundwater. Fresh core sediments were compared by depth to capture the changes in sediment structure, sediment minerals, biomass, and pore water geochemistry in terms of major and trace elements including pollutants, cations, anions, and organic acids. Soil porewater samples were matched to groundwater level, flow rate, and preferential flows and compared to homogenized groundwater-only samples from neighboring monitoring wells. Groundwater analysis of nearby wells only revealed high sulfate and nitrate concentrations while the same analysis using sediment pore water samples with depth was able to suggest areas high in sulfate- and nitrate-reducing bacteria based on their decreased concentration and production of reduced by-products that could not be seen in the groundwater samples. Positive correlations among porewater content, total organic carbon, trace metals and clay minerals revealed a more complicated relationship among contaminant, sediment texture, groundwater table, and biomass. The fluctuating capillary interface had high concentrations of Fe and Mn-oxides combined with trace elements including U, Th, Sr, Ba, Cu, and Co. This suggests the mobility of potentially hazardous elements, sediment structure, and biogeochemical factors are all linked together to impact microbial communities, emphasizing that solid interfaces play an important role in determining the abundance of bacteria in the sediments

HIV-1 protease inhibitors and clinical malaria: A secondary analysis of the AIDS Clinical Trials Group A5208 study

HIV-1 protease inhibitors (PIs) have antimalarial activity in vitro and in murine models. The potential beneficial effect of HIV-1 PIs on malaria has not been studied in clinical settings. We used data from Adult AIDS Clinical Trials Group A5208 sites where malaria is endemic to compare the incidence of clinically diagnosed malaria among HIV-infected adult women randomized to either lopinavir/ritonavir (LPV/r)-based antiretroviral therapy (ART) or to nevirapine (NVP)-based ART. We calculated hazard ratios and 95% confidence intervals. We conducted a recurrent events analysis that included both first and second clinical malarial episodes and also conducted analyses to assess the sensitivity of results to outcome misclassification. Among the 445 women in this analysis, 137 (31%) received a clinical diagnosis of malaria at least once during follow-up. Of these 137, 72 (53%) were randomized to LPV/r-based ART. Assignment to the LPV/r treatment group (n = 226) was not consistent with a large decrease in the hazard of first clinical malarial episode (hazard ratio = 1.11 [0.79 to 1.56]). The results were similar in the recurrent events analysis. Sensitivity analyses indicated the results were robust to reasonable levels of outcome misclassification. In this study, the treatment with LPV/r compared to NVP had no apparent beneficial effect on the incidence of clinical malaria among HIV-infected adult women. Additional research concerning the effects of PI-based therapy on the incidence of malaria diagnosed by more specific criteria and among groups at a higher risk for severe disease is warranted. Copyrigh

Transmitted Drug Resistance in Persons with Acute/Early HIV-1 in San Francisco, 2002-2009

Transmitted HIV-1 drug resistance (TDR) is an ongoing public health problem, representing 10-20% of new HIV infections in many geographic areas. TDR usually arises from two main sources: individuals on antiretroviral therapy (ART) who are failing to achieve virologic suppression, and individuals who acquired TDR and transmit it while still ART-naïve. TDR rates can be impacted when novel antiretroviral medications are introduced that allow for greater virologic suppression of source patients. Although several new HIV medications were introduced starting in late 2007, including raltegravir, maraviroc, and etravirine, it is not known whether the prevalence of TDR was subsequently affected in 2008-2009.We performed population sequence genotyping on individuals who were diagnosed with acute or early HIV (<6 months duration) and who enrolled in the Options Project, a prospective cohort, between 2002 and 2009. We used logistic regression to compare the odds of acquiring drug-resistant HIV before versus after the arrival of new ART (2005-2007 vs. 2008-2009). From 2003-2007, TDR rose from 7% to 24%. Prevalence of TDR was then 15% in 2008 and in 2009. While the odds of acquiring TDR were lower in 2008-2009 compared to 2005-2007, this was not statistically significant (odds ratio 0.65, 95% CI 0.31-1.38; p = 0.27).Our study suggests that transmitted drug resistance rose from 2003-2007, but this upward trend did not continue in 2008 and 2009. Nevertheless, the TDR prevalence in 2008-2009 remained substantial, emphasizing that improved management strategies for drug-resistant HIV are needed if TDR is to be further reduced. Continued surveillance for TDR will be important in understanding the full impact of new antiretroviral medications