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Browsing by Author "Zhang, Hui"

Now showing 1 - 3 of 3
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    Dayside Magnetospheric and Ionospheric Responses to a Foreshock Transient on 25 June 2008: 1. FLR Observed by Satellite and Ground-Based Magnetometers
    Shen, Xiao-Chen; Shi, Quanqi; Wang, Boyi; Zhang, Hui; Hudson, Mary K.; Nishimura, Yukitoshi; Hartinger, Michael D.; Tian, Anmin; Zong, Qiu-Gang; Rae, I. J.; Degeling, Alexander W. (2018-08)
    As one type of driver of magnetospheric Alfven waves, foreshock transients have received less attention than, for example, the Kelvin-Helmholtz instability, discrete and broadband frequency solar wind dynamic pressure oscillations, and interplanetary shocks. Previous works show that foreshock transients can induce both Alfven mode and compressional mode Pc 3-5 ULF waves inside the magnetosphere. However, to our knowledge, none of these reported Pc 3-5 waves, induced by foreshock transients, are proved to be localized in the magnetosphere. In this paper, using in situ and ground-based observations, we report the generation of localized magnetospheric compressional waves and field line resonances (FLRs) by a foreshock transient. Both the foreshock transient and Pc 5 ULF waves were found on the duskside; while on the morning side of the magnetosphere, no clear wave signatures were captured. Our results demonstrate that in addition to the global effects of foreshock transients on the magnetosphere reported earlier, foreshock transients can also generate localized magnetospheric responses in the Pc 5 range with clear dawn-dusk asymmetry. A suite of eight dayside spacecraft plus ground magnetometer measurements make possible the determination of the foreshock transient driver and dawn-dusk asymmetry of the magnetospheric response not previously reported with such a complete data set.
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    Modeling Multi-level Incentives in Health Care: A Multiscale Decision Theory Approach
    Zhang, Hui (Virginia Tech, 2016-04-08)
    Financial incentives offered by payers to health care providers and patients have been identified as a key mechanism to lower costs while improving quality of care. How to effectively design incentive programs that can align the varying objectives of health care stakeholders, as well as predict programs' performance and stakeholders' decision response is an unresolved research challenge. The objective of this study is to establish a novel approach based on multiscale decision theory (MSDT) that can effectively model and efficiently analyze such incentive programs, and the complex health care system in general. The MSDT model captures the interdependencies of stakeholders, their decision processes, uncertainties, and how incentives impact decisions and outcomes at the payer, hospital, physician, and patient level. In the first part of this thesis, we study the decision processes of agents pertaining to the investment and utilization of imaging technologies. We analyze the payer-hospital-physician relationships and later extend the model to include radiologist and patient as major stakeholders in the second part of this thesis. We focus on a specific incentive program, the Medicare Shared Savings Program (MSSP) for Accountable Care Organizations (ACOs). The multi-level interactions between agents are mathematically formulated as a sequential non-cooperative game. We derive the equilibrium solutions using the subgame perfect Nash equilibrium (SPNE) concept and the backward induction principle, and determine the conditions under which the MSSP incentive leads to the desired outcomes of cost reduction and quality of care improvements. In the third part of this thesis, we study the multi-level decision making in chronic disease management. We model and analyze patients' and physicians' decision processes as a general-sum stochastic game with perfect information and switching control structure. We incorporate the Health Belief Model (HBM) as the theoretical foundation to capture the behavioral aspect of agents. We analyze how incentives and interdependencies affect patients' engagement in health-promoting activities and physicians' delivery of primary care services. We show that a re-alignment of incentives can improve the effectiveness of chronic disease management.
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    Reprogramming macrophage orientation by microRNA 146b targeting transcription factor IRF5
    Peng, Liang; Zhang, Hui; Hao, Yuanyuan; Xu, Feihong; Yang, Jianjun; Zhang, Ruihua; Lu, Geming; Zheng, Zihan; Cui, Miao; Qi, Chen-Feng; Chen, Chun; Wang, Juan; Hu, Yuan; Wang, Di; Pierce, Susan; Li, Liwu; Xiong, Huabao (2016-12)
    The regulation of macrophage orientation pathological conditions is important but still incompletely understood. Here, we show that IL-10 and Rag1 double knockout mice spontaneously develop colitis with dominant M1 macrophage phenotype, suggesting that IL-10 regulates macrophage orientation in inflammation. We demonstrate that IL-10 stimulation induced miR-146b expression, and that the expression of miR-146b was impaired in IL-10 deficient macrophages. Our data show that miR-146b targets IRF5, resulting in the regulation of macrophage activation. Furthermore, miR-146b deficient mice developed intestinal inflammation with enhanced M1 macrophage polarization. Finally, miR-146b mimic treatment significantly suppresses M1 macrophage activation and ameliorates colitis development in vivo. Collectively, the results suggest that IL-10 dependent miR-146b plays an important role in the modulation of M1 macrophage orientation. (C) 2016 The Authors. Published by Elsevier B.V.