Browsing by Author "Wang, Rui"
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Item Correcting a major error in assessing organic carbon pollution in natural waters(Science Advances, 2021-04-14) Jiao, Nianzhi; Liu, Jihua; Edwards, Bethanie; Lv, Zongqing; Cai, Ruanhong; Liu,Yongqin; Xiao, Xilin; Wang, Jianning; Jiao, Fanglue; Wang, Rui; Huang, Xingyu; Guo, Bixi; Sun, Jia; Zhang, Rui; Zhang, Yao; Tang, Kai; Zheng, Qiang; Azam, Farooq; Batt, John; Cai, Wei-Jun; He, Chen; Herndl, Gerhard J.; Hill, Paul; Hutchins, David; LaRoche, Julie; Lewis, Marlon; MacIntyre, Hugh; Polimene, Luca; Robinson, Carol; Shi, Quan; Suttle, Curtis A.; Thomas, Helmuth; Wallace, Douglas; Legendre, LouisMicrobial degradation of dissolved organic carbon (DOC) in aquatic environments can cause oxygen depletion, water acidification, and CO2 emissions. These problems are caused by labile DOC (LDOC) and not refractory DOC (RDOC) that resists degradation and is thus a carbon sink. For nearly a century, chemical oxygen demand (COD) has been widely used for assessment of organic pollution in aquatic systems. Here, we show through a multicountry survey and experimental studies that COD is not an appropriate proxy of microbial degradability of organic matter because it oxidizes both LDOC and RDOC, and the latter contributes up to 90% of DOC in high-latitude forested areas. Hence, COD measurements do not provide appropriate scientific information on organic pollution in natural waters and can mislead environmental policies. We propose the replacement of the COD method with an optode-based biological oxygen demand method to accurately and efficiently assess organic pollution in natural aquatic environments.Item The effect of early enrollment in dual-language immersion programs on children’s English reading development: findings from a 5-year longitudinal study(International Journal of Bilingual Education and Bilingualism, 2022-05-30) Shen, Ye; Wang, Rui; Zhang, Fan; Barbieri, Christina Areizaga; Pasquarella, AdrianThe present study examined the effect of children’s enrollment in U.S. dual-language immersion (DLI) programs in first grade on English development across five years, using the Early Childhood Longitudinal Study, Kindergarten Class of 2011 (ECLS-K:2011) database. Propensity score matching was used to create comparable groups of DLI and non-DLI students based on students’ kindergarten reading performance and a series of student-, family-, and school-level characteristics. Growth curve models demonstrate that first-grade DLI enrollment had a positive effect on children’s English reading growth from Grade 1 to 5. Children who enrolled in DLI experienced greater improvements by Grade 5. We also found that first-grade teacher judgment was related to children’s initial reading performance but not their reading growth. Implications related to DLI programs, teacher practices, and bilingual educational policies are discussed.Item Examining the causal effects of the foundations of college math program in Delaware: an application of regression discontinuity and propensity score matching analysis(University of Delaware, 2020) Wang, RuiRemedial education, also known as developmental education, college preparation courses, or skills courses, are usually offered by two-year and four-year colleges and universities in the United States to students deemed underprepared for college-level coursework. In sharp contrast with the prevalent offering of remedial courses in post-secondary education, research on the causal effects of placement in remedial courses is both mixed and limited, largely due to the failure to control for important selection biases. This dissertation seeks to address this gap in the literature through a partnership with the Delaware Department of Education (DDOE), which has taken action to intervene at an earlier stage by providing a Foundations of College Mathematics (FCM) course in twelfth grade to better prepare graduates for college-level math courses. ☐ In this dissertation, I apply two causal research designs to examine the impact of the FCM course offered to high school seniors who did not meet the College and Career Ready target score on the SAT Math test. The results suggest that a regression discontinuity (RD) design is not applicable to the program due to lack of sufficient “discontinuity” at the cut-score. However, a propensity score (PS) design using matched samples based on single-level (SL), multi-level (ML) and neural network (NN) models shows that the FCM course produced a significant reduction in students’ probability of taking a remedial math course in a DE college. Students who participated in the FCM courses in the twelfth grade and then enrolled in a DE college were 63% to 70% less likely to take a remedial math course during their first year in college. While there were no significant impacts on the probability of enrolling in a college in general, the FCM course may have had significant impacts on students’ likelihood of enrolling in a Delaware college. However, it is unclear whether students who enrolled in the FCM course do so because they had preexisting aspirations to enroll at a DE college, and thus the difference in enrollment rates may not be due to the FCM course. One model also showed a significant increase in students’ probability of earning a C or higher grade in a non-remedial math course during their first year in college, suggesting that the impact of FCM was not simply a reduction in remediation but improvement in college-level math skills. ☐ Additionally, I discuss implications of the findings and the application of RD and PS designs in similar pilot programs with limited sample sizes of students and schools in the treatment group. Considering the promising results from this study, future research on the FCM course should include a greater number of schools and eligible students enrolled in the FCM course in the twelfth grade. Long-term effects, and differential treatment impacts across different groups of students should also be investigated. In terms of methodology, this study also has implications for simulation studies examining best practices for utilizing NN in estimating PS.Item Purchases, Consumption, and BMI of SNAP Farmers’ Market Shoppers(Journal of Hunger and Environmental Nutrition, 2021-10-31) Karpyn, Allison; Pon, Julia; Grajeda, Sara Bernice; Wang, Rui; Merritt, Kathryn E.; Tracy, Tara; May, Henry; Sawyer-Morris, Ginnie; Humphrey, Layne; Hunt, AlanPurchasing, consumption, and health data from 3,073 Supplemental Nutrition Assistance Program Shoppers (SNAP) at 77 U.S. farmers’ markets (FMs) are reported. Descriptive and bivariate analyses indicate SNAP households spent $345/month on all groceries and $153.76/month on all fruit and vegetable (FV) purchases; daily FV consumption significantly correlated with percentage of household expenditures on FV and household FV dollars/month. Females and Hispanics spent significantly more on FV. 82% of participants were food insecure and 26.1% reported fair/poor health. Average BMI was 28.5. Findings suggest SNAP FM shoppers have unique FV expenditure and consumption patterns, despite higher food insecurity, meriting future research.Item Understanding Impacts of SNAP Fruit and Vegetable Incentive Program at Farmers’ Markets: Findings from a 13 State RCT(International Journal of Environmental Research and Public Health, 2022-06-17) Karpyn, Allison; Pon, Julia; Grajeda, Sara B.; Wang, Rui; Merritt, Kathryn E.; Tracy, Tara; May, Henry; Sawyer-Morris, Ginnie; Halverson, McKenna M.; Hunt, AlanDisparities in healthy food access and consumption are a major public health concern. This study reports the findings from a two-year randomized control trial conducted at 77 farmers’ markets (FMs) in 13 states and the District of Columbia that sought to understand the impact of fruit and vegetable (FV) incentive vouchers, randomly issued at varied incentive levels to Supplemental Nutrition Assistance Program (SNAP) recipients, for use at FMs. Measures included FV and overall household food purchasing; FV consumption; food insecurity; health status; market expenditure; and demographics. A repeated-measures mixed-effects analysis and the Complier Average Causal Effect (CACE) were used to examine outcomes. Despite 82% reporting food insecurity in the prior year, the findings showed that financial incentives at FMs had statistically significant, positive effects on FV consumption; market expenditures increased with added incentives. SNAP recipients receiving an incentive of USD 0.40 for every USD 1.00 in SNAP spent an average of USD 19.03 per transaction, while those receiving USD 2 for every USD 1 (2:1) spent an average of USD 36.28 per transaction. The data showed that the incentive program at the highest level (2:1) maximally increased SNAP FM expenditure and FV consumption, increasing the latter by 0.31 daily cups among those who used their incentive (CACE model).