• Journal of the Korean earth science society
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• v.44 no.6
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• pp.578-593
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• 2023

Intense convective activity and heavy precipitation inundated Seoul and its metropolitan area on July 15, 2017. This study investigated the synoptic-scale meteorological drivers of cold cloud genesis of this event. The WRF-Chem (Weather Research and Forecasting model coupled with Chemistry) model was employed to explore the intricate interplay between meteorological factors and the indirect effects of PM_2.5 aerosols originating from eastern China. The PM_2.5 aerosols' indirect effect was quantified by contrasting outcomes between the comprehensive Aerosol Radiation Interaction experiment (encompassing aerosol radiation feedback, cloud chemistry processes, and wet scavenging in the WRF-Chem model) and ACR (Aerosol Cloud Radiation interaction) experiment. The ACR experiment specifically excluded aerosol radiation feedback while incorporating only cloud chemistry processes and wet scavenging. Results indicated that in the early hours of July 15, 2017, a convergence of warm, moisture-laden airflow originating from southeast China and the East China Sea unfolded over the Yellow Sea. This convergence was driven by the juxtaposition of a low-pressure system over the Chinese mainland and Northwest Pacific high. Notably, at approximately 12 km altitude, the resultant convective clouds were characterized by the presence of ice crystals, a hallmark of continental-origin cold clouds. The WRF-Chem model simulations elucidated the role of PM_2.5 aerosols from eastern China, attributing 5.7, 10.4, and 10.8% to cloud water, ice crystal column, and liquid water column formation, respectively, within the developing cold clouds. Thus, this study presented a meteorological mechanism elucidating the formation of deep convective clouds over the Yellow Sea and the indirect effects of PM_2.5 aerosols originating from eastern China.

• Tuberculosis and Respiratory Diseases
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• v.48 no.4
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• pp.448-463
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• 2000

Background : Pulmonary infiltrate is a frequent cause of morbidity and mortality in patients with leukemia. It is often hard to obtain a reliable diagnosis by clinical and radiologic findings alone. The aim of this study was to evaluate diagnostic and therapeutic benefits of invasive procedures for new lung infiltrates in leukemia. Methods : Patients with leukemia who developed new lung infiltrates from December 1994 to March 1999 were included in this study. These patients were classified into the empirical group who received empirical therapy only and into the invasive group who underwent bronchoscopy or surgical lung biopsy for the diagnostic purpose of new lung infiltrates. A retrospective chart review was done to find the etiologies of new lung infiltrates, the yield of invasive procedures, outcome as well as predicting factors for survival. Results : 1) One hundred-two episodes of new lung infiltrates developed in 90 patients with leukemia. Invasive procedures were performed in 44 episodes while 58 episodes were treated with empirical therapy only. 2) Invasive procedures yielded a specific diagnosis in 72.7%(32/44), of which 78.1% had infectious etiology. Therapeutic plan was changed in 52.3%(23/44) of patients after invasive procedures. None of them showed procedure-related mortality. 3) The overall survival rate was 62.7%(64/102). Survival rate in the invasive group (79.5%) was significantly better than that in the empirical group (50.0%) (p=0.002). 4) Upon multivariate analysis, the performance of invasive procedures, no need for mechanical ventilation and achievement of complete remission of leukemia after induction chemotherapy were the independent predicting factors for survival in patients with leukemia and new lung infiltrates. Conclusion : Bronchoscopy and surgical lung biopsy are useful in the diagnosis of new lung infiltrates in patients with leukemia. However, survival benefits of invasive procedures should be considered together with disease status of leukemia and severity of respiratory compromise.