Browsing by Author "Zhang, Jing"
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Item GROWTH AND FMR CHARACTERIZATION OF IN-PLANE MAGNETIZATION GARNET THIN-FILMS(2004-12-09) Zhang, Jing; Mayergoyz, Isaak D; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Planar magnetization Bi-doped garnet thin-films were successfully grown for magneto-optical imaging applications. These films are grown using the liquid phase epitaxy method, which produces single crystal, high quality films. The melt composition that is used to grow these garnets is selected in order to produce planar magnetization films with low magneto-crystalline and uniaxial anisotropies. Also, this melt composition is designed to incorporate more bismuth into the film, thereby increasing the specific Faraday rotation of the film. This effectively tailors the films to be highly sensitive to spatial magnetic field distributions. The garnet films that are grown from this process are characterized by measuring their ferromagnetic resonance, which allows their magneto-crystalline and uniaxial anisotropies to be determined. An imager system that utilizes these garnet films has also been developed to visualize magnetic recording from cassette tapes. The Federal Bureau of Investigation (FBI) uses these captured images for forensic applications.Item The Impact of Excluding Trials from Network Meta-Analyses - An Empirical Study(PLoS (Public Library of Science), 2016-12-07) Zhang, Jing; Yuan, Yiping; Chu, HaitaoNetwork meta-analysis (NMA) expands the scope of a conventional pairwise meta-analysis to simultaneously compare multiple treatments, which has an inherent appeal for clinicians, patients, and policy decision makers. Two recent reports have shown that the impact of excluding a treatment on NMAs can be substantial. However, no one has assessed the impact of excluding a trial from NMAs, which is important because many NMAs selectively include trials in the analysis. This article empirically examines the impact of trial exclusion using both the arm-based (AB) and contrast-based (CB) approaches, by reanalyzing 20 published NMAs involving 725 randomized controlled trials and 449,325 patients. For the population-averaged absolute risk estimates using the AB approach, the average fold changes across all networks ranged from 1.004 (with standard deviation 0.004) to 1.072 (with standard deviation 0.184); while the maximal fold changes ranged from 1.032 to 2.349. In 12 out of 20 NMAs, a 1.20-fold or larger change is observed in at least one of the population- averaged absolute risk estimates. In addition, while excluding a trial can substantially change the estimated relative effects (e.g., log odds ratios), there is no systematic difference in terms of changes between the two approaches. Changes in treatment rankings are observed in 7 networks and changes in inconsistency are observed in 3 networks. We do not observe correlations between changes in treatment effects, treatment rankings and inconsistency. Finally, we recommend rigorous inclusion and exclusion criteria, logical study selection process, and reasonable network geometry to ensure robustness and generalizability of the results of NMAs.Item THE IMPACT OF WATER QUALITY ON HEALTH IN RURAL CHINA(2011) Zhang, Jing; Hellerstein, Judith; Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Providing people with safe drinking water is one of the most important health-related infrastructure programs in the world. This dissertation investigates the effects of a major water improvement program in rural China on the health of adults and children. Using panel data covering about 4,500 households from 1989 to 2006, I estimate the impact of introducing village-level access to water from water plants on various measures of health. Ordinary least squares (OLS) estimation of the impact suggests a weak positive influence of the program on people's health status, but these results may be contaminated by endogenous timing and placement of the water quality interventions across China. To address potential endogeneity problems, I use topographic characteristics of communities as instruments for program placement, as these characteristics affect the costs of the construction of water plants and pipelines into villages. My instrumental variables (IV) results show that the introduction of treated plant water into villages has had a stronger impact on the health status of both adults and children. However, the IV strategy may result into overestimation due to some omitted variables. Combining both OLS and IV estimates, I find that the illness incidence of adults decreased by 11 to 50 percent and their weight-for-height increased by 0.835 to 2.580 kg/m following the program implementation. There was also an improvement in self-reports of health. Children's weight-for-height and height itself both rose, by 0.446 to 0.754 kg/m and 0.962 to 2.489 cm respectively, as a result of the program. Using a variety of robustness checks, I show that the results are not driven by measurement errors, omitted variable bias, or attrition bias, and that the mechanism by which the program was effective was via improved water quality rather than simply via increased access to water. No obvious heterogeneous treatment effects are found across income and educational groups.Item Maternal experiences of intimate partner violence and C-reactive protein levels in young children in Tanzania(Elsevier, 2018-12) Slopen, Natalie; Zhang, Jing; Urlacher, Samuel S.; De Silva, Gretchen; Mittal, MonaIntimate partner violence (IPV) is a critical public health issue that impacts women and children across the globe. Prior studies have documented that maternal experiences of IPV are associated with adverse psychological and physical health outcomes in children; however, research on the underlying physiological pathways linking IPV to these conditions is limited. Drawing on data from the 2010 Tanzania Demographic and Health Survey, we examined the relationship between maternal report of IPV in the past 12 months and inflammation among children ages 6 months to 5 years. Our study included 503 children who were randomly selected to provide a blood sample and had a mother who had ever been married and who had completed the Domestic Violence Module, which collected information on physical, sexual, and emotional violence. Analyses were stratified based on a threshold for acute immune activation status, defined by the threshold of CRP>1.1 mg/L for young children in Tanzania. In bivariate analyses, healthy children whose mothers reported IPV showed a marginally elevated median CRP level compared to children whose mothers did not report IPV (0.35 vs. 0.41 mg/L; p = 0.13). Similarly, among children with active or recent infections, those whose mothers reported IPV had an elevated median CRP compared to children whose mothers did not (4.06 vs 3.09 mg/L; p = 0.03). In adjusted multiple variable regression models to account for child, mother, and household characteristics, maternal IPV was positively associated with (log) CRP in both healthy children and children with active or recent infection. Although longitudinal research with additional biomarkers of inflammation is needed, our results provide support for the hypothesis that inflammation may function as a biological pathway linking maternal IPV to poor psychological and physical health outcomes among children of mothers who are victimized—and this may extend to very young children and children in non-Western contexts.