394 research outputs found

    Dust aerosol impact on North Africa climate: a GCM investigation of aerosol-cloud-radiation interactions using A-Train satellite data

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    The climatic effects of dust aerosols in North Africa have been investigated using the atmospheric general circulation model (AGCM) developed at the University of California, Los Angeles (UCLA). The model includes an efficient and physically based radiation parameterization scheme developed specifically for application to clouds and aerosols. Parameterization of the effective ice particle size in association with the aerosol first indirect effect based on ice cloud and aerosol data retrieved from A-Train satellite observations have been employed in climate model simulations. Offline simulations reveal that the direct solar, IR, and net forcings by dust aerosols at the top of the atmosphere (TOA) generally increase with increasing aerosol optical depth. When the dust semi-direct effect is included with the presence of ice clouds, positive IR radiative forcing is enhanced since ice clouds trap substantial IR radiation, while the positive solar forcing with dust aerosols alone has been changed to negative values due to the strong reflection of solar radiation by clouds, indicating that cloud forcing associated with aerosol semi-direct effect could exceed direct aerosol forcing. With the aerosol first indirect effect, the net cloud forcing is generally reduced in the case for an ice water path (IWP) larger than 20 g m<sup>−2</sup>. The magnitude of the reduction increases with IWP. <br><br> AGCM simulations show that the reduced ice crystal mean effective size due to the aerosol first indirect effect results in less OLR and net solar flux at TOA over the cloudy area of the North Africa region because ice clouds with smaller size trap more IR radiation and reflect more solar radiation. The precipitation in the same area, however, increases due to the aerosol indirect effect on ice clouds, corresponding to the enhanced convection as indicated by reduced OLR. Adding the aerosol direct effect into the model simulation reduces the precipitation in the normal rainfall band over North Africa, where precipitation is shifted to the south and the northeast produced by the absorption of sunlight and the subsequent heating of the air column by dust particles. As a result, rainfall is drawn further inland to the northeast. This study represents the first attempt to quantify the climate impact of the aerosol indirect effect using a GCM in connection with A-Train satellite data. The parameterization for the aerosol first indirect effect developed in this study can be readily employed for application to other GCMs

    Research on Influence of Clopidogrel on Life Quality in Patients with Transient Ischemic Attack and its Influencing Factors

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    Purpose: To analyze the basic situation and health related quality of life (HRQOL) results of patients with transient ischemic attack (TIA), and to study the influencing factors of health related quality of life in patients receiving clopidogrel. Method: Divide the TIA patients into clopidogrel group, aspirin group and untreated group. Measure HRQOL scores of TIA patients using the short form 36 questionnaire (SF-36) scale and analyze influencing factors of HRQOL with one-way ANOVA and multivariate stepwise linear regression statistical methods. Results: The differences of HRQOL scores among three groups are of statistical significance (F = 4.29, P = 0.00). There is no difference in HRQOL score between clopidogrel group and aspirin group (t = 5.35, P = 0.00), but HRQOL scores of clopidogrel group and aspirin group are higher than those of the untreated group (t = 6.14, P = 0.00; t = 5.16, P = 0.00). The HRQOL scores of clopidogrel group are positively correlated with diet, exercise, gender and family harmony (P < 0.05), but negatively correlated with diabetes, hypertension, smoking, drinking, hyperlipidemia, age, career and ABCD2 score (P < 0.05). Conclusion: TIA patients who received secondary prevention with clopidogrel and aspirin show better life quality results than those who did not. There were many factors influencing clopidogrel's treatment effect. Paying attention to middle-aged and elderly, the obese, mental workers and female TIA patients, teach TIA patients to quit smoking, drinking and eating low-salt and low-fat food, actively treating their hypertension, hyperlipidemia and diabetes and laying emphasis on psychological counseling and exercise can significantly improve the treatment effect of clopidogrel.

    Deep Historical Borrowing Framework to Prospectively and Simultaneously Synthesize Control Information in Confirmatory Clinical Trials with Multiple Endpoints

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    In current clinical trial development, historical information is receiving more attention as providing value beyond sample size calculation. Meta-analytic-predictive (MAP) priors and robust MAP priors have been proposed for prospectively borrowing historical data on a single endpoint. To simultaneously synthesize control information from multiple endpoints in confirmatory clinical trials, we propose to approximate posterior probabilities from a Bayesian hierarchical model and estimate critical values by deep learning to construct pre-specified decision functions before the trial conduct. Simulation studies and a case study demonstrate that our method additionally preserves power, and has a satisfactory performance under prior-data conflict

    Top-down effects of filter-feeding fish and bivalves moderate bottom-up effects of nutrients on phytoplankton in subtropical shallow lakes: An outdoor mesocosm study

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    Biomanipulation has been widely used in the ecological restoration of eutrophic lakes for decades. However, biomanipulation is prone to failure if external nutrient loads are not reduced. In order to explore the importance of filter-feeding fish and bivalves on algal control, an outdoor mesocosm experiment was conducted using different nutrient concentrations. Four treatments simulating daily loads of nutrients in Lake Taihu were studied: current, two times, and three times average daily loads of nutrients with both fish (Aristichthys nobilis) and Asian clam (Corbicula fluminea) and as a control current daily loads without fish or bivalves. Results showed that stocking of filter-feeding fish and bivalves (80 g m-3 bighead carp; 200 g cm-2 clams) at two times daily nutrient loads could effectively control water column Chl a concentrations and phytoplankton biomass. At higher nutrient concentrations (TN & GE; 260 & mu;g L-1 d-1; TP & GE; 10 & mu;g L-1 d-1), top-down control of filter-feeding fish and bivalves was less effective and bottom-up effects resulted in significant increases of Chl a concentration. Thus, as phytoplankton biomass in freshwater ecosystems is determined by both the top-down effects of predators and the bottom-up effects of nutrients, external loadings should be controlled when filter-feeding fish and bivalves are used for algal control to ensure the efficacy of biomanipulation.A combination of filter-feeding fish and clams suppressed phytoplankton, which could not be affected by low-level nutrients.Bottom-up effects at high-level nutrients on phytoplankton overcome top-down effects, indicating that nutrient levels should be controlled to optimize the effect of the intervention.imag

    The Effectiveness of an eHealth Family-Based Intervention Program in Patients With Uncontrolled Type 2 Diabetes Mellitus (T2DM) in the Community Via WeChat: Randomized Controlled Trial

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    Background: Intervention based on family support and risk perception can enhance type 2 diabetes mellitus (T2DM) patients’ self-care activities. In addition, eHealth education is considered to improve family members’ support for patients with T2DM. However, there is little evidence from rigorously designed studies on the effectiveness of an intervention combining these approaches. Objective: This randomized controlled trial (RCT) aimed to assess the effectiveness of an eHealth family-based health education intervention for patients with T2DM to improve their glucose control, risk perception, and self-care behaviors. Methods: This single-center, 2-parallel-group RCT was conducted between 2019 and 2020. Overall, 228 patients were recruited from Jiading District, Shanghai, and randomly divided into intervention and control groups. The intervention group received an eHealth family intervention based on community management via WeChat, whereas the control group received usual care. The primary outcome was the glycated hemoglobin (HbA1c) level of the patients with T2DM, and the secondary outcomes were self-management behavior (general and specific diet, exercise, blood sugar testing, foot care, and smoking), risk perception (risk knowledge, personal control, worry, optimism bias, and personal risk), and family support (supportive and nonsupportive behaviors). A 2-tailed paired-sample t test was used to compare the participants at baseline and follow-up within the control and intervention groups. An analysis of covariance was used to measure the intervention effect. Results: In total, 225 patients with T2DM were followed up for 1 year. After intervention, they had significantly lower HbA1c values (β=–.69, 95% CI –0.99 to –0.39; PP=.003), special diet (β=.71, 95% CI 0.34 to 1.09; PP=.04), foot care (β=1.82, 95% CI 1.23 to 2.42; PPPP=.001), optimism bias (β=.26, 95% CI 0.09 to 0.43; P=.003), and supportive behaviors (β=5.52, 95% CI 4.03 to 7.01; P\u3c.001). Conclusions: The eHealth family-based intervention improved glucose control and self-care activities among patients with T2DM by aiding the implementation of interventions to improve T2DM risk perceptions among family members. The intervention is generalizable for patients with T2DM using health management systems in community health centers. Trial Registration: Chinese Clinical Trial Registry ChiCTR1900020736; https://www.chictr.org.cn/showprojen.aspx?proj=3121
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