Atlantic origin of the increasing Asian westerly jet interannual variability.

The summer Eurasian westerly jet is reported to become weaker and wavier, thus promoting the frequent weather extremes. However, the primary driver of the changing jet stream remains in debate, mainly due to the regionality and seasonality of the Eurasian jet. Here we report a sharp increase, by approximately 140%, in the interannual variability of the summertime East Asian jet (EAJ) since the end of twentieth century. Such interdecadal change induces considerable changes in the large-scale circulation pattern across Eurasia, and consequently weather and climate extremes including heatwaves, droughts, and Asian monsoonal rainfall regime shifts. The trigger mainly emerges from preceding February North Atlantic seesaw called Scandinavian pattern (contributing to 81.1 ± 2.9% of the enhanced EAJ variability), which harnesses the "cross-seasonal-coupled oceanic-atmospheric bridge" to exert a delayed impact on EAJ and thus aids relevant predictions five months in advance. However, projections from state-of-the-art models with prescribed anthropogenic forcing exhibit no similar circulation changes. This sheds light on that, at the interannual timescale, a substantial portion of recently increasing variability in the East Asian sector of the Eurasian westerly jet arises from unforced natural variability.

Constraints on regional projections of mean and extreme precipitation under warming.

The projected changes in the hydrological cycle under global warming remain highly uncertain across current climate models. Here, we demonstrate that the observational past warming trend can be utilized to effectively co1nstrain future projections in mean and extreme precipitation on both global and regional scales. The physical basis for such constraints relies on the relatively constant climate sensitivity in individual models and the reasonable consistency of regional hydrological sensitivity among the models, which is dominated and regulated by the increases in atmospheric moisture. For the high-emission scenario, on the global average, the projected changes in mean precipitation are lowered from 6.9 to 5.2% and those in extreme precipitation from 24.5 to 18.1%, with the inter-model variances reduced by 31.0 and 22.7%, respectively. Moreover, the constraint can be applied to regions in middle-to-high latitudes, particularly over land. These constraints result in spatially resolved corrections that deviate substantially and inhomogeneously from the global mean corrections. This study provides regionally constrained hydrological responses over the globe, with direct implications for climate adaptation in specific areas.

Recent Advances in Understanding Multi-scale Climate Variability of the Asian Monsoon.

Studies of the multi-scale climate variability of the Asian monsoon are essential to an advanced understanding of the physical processes of the global climate system. In this paper, the progress achieved in this field is systematically reviewed, with a focus on the past several years. The achievements are summarized into the following topics: (1) the onset of the South China Sea summer monsoon; (2) the East Asian summer monsoon; (3) the East Asian winter monsoon; and (4) the Indian summer monsoon. Specifically, new results are highlighted, including the advanced or delayed local monsoon onset tending to be synchronized over the Arabian Sea, Bay of Bengal, Indochina Peninsula, and South China Sea; the basic features of the record-breaking mei-yu in 2020, which have been extensively investigated with an emphasis on the role of multi-scale processes; the recovery of the East Asian winter monsoon intensity after the early 2000s in the presence of continuing greenhouse gas emissions, which is believed to have been dominated by internal climate variability (mostly the Arctic Oscillation); and the accelerated warming over South Asia, which exceeded the tropical Indian Ocean warming, is considered to be the main driver of the Indian summer monsoon rainfall recovery since 1999. A brief summary is provided in the final section along with some further discussion on future research directions regarding our understanding of the Asian monsoon variability.

Fine particulate matter (PM2.5) trends from land surface changes and air pollution policies in China during 1980-2020.

High levels of fine particulate matter (PM2.5) pose a severe air pollution challenge in China. Both land use changes and anthropogenic emissions can affect PM2.5 concentrations. Only a few studies have addressed the long-term impact of land surface changes on PM2.5 in China. We conducted a comprehensive analysis of PM2.5 trends over China using the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) during 1980-2020. The monthly mean PM2.5 concentrations of MERRA-2 were evaluated across mainland China against independent surface measurements from 2013 to 2020, showing a good agreement. For the trend analysis, China was subdivided into six regions based on land use and ambient aerosols types. Our results indicate an overall significant PM2.5 increase over China during 1980-2020 with major changes in-between. Notwithstanding continued urbanization and associated anthropogenic activities, the PM2.5 reversed to a downward trend around 2007 over most regions except for the part of China that is most affected by desert dust. Statistical analysis suggests that PM2.5 trends during 1980-2010 were associated with urban expansion and deforestation over eastern and southern China. The trend reversal around 2007 is mainly attributed to Chinese air pollution control measures. A multiple linear regression analysis reveals that PM2.5 variability is linked to soil moisture and vegetation. Our results suggest that land use and land cover changes as well as pollution controls strongly influenced PM2.5 trends and that drought conditions affect PM2.5 particularly over desert and forest regions of China. This work contributes to a better understanding of the changes in PM2.5 over China.

Integrated safety summary of phase II and III studies comparing oral nemonoxacin and levofloxacin in community-acquired pneumonia.

BACKGROUND: Nemonoxacin, a novel nonfluorinated quinolone, has broad-spectrum antibacterial activity, including activity against antibiotic-resistant strains, and was developed for treating community-acquired pneumonia (CAP). This report provides an integrated safety summary of oral nemonoxacin from two phase II and one phase III clinical studies. METHODS: Patients with mild CAP were randomized for treatment with nemonoxacin 500 mg (NEMO-500MG), nemonoxacin 750 mg (NEMO-750MG), or levofloxacin 500 mg (LEVO), orally, once daily, for 7-10 days. Hematological, gastrointestinal, and hepatic disorders; electrocardiography abnormalities; and reported quinolone-associated clinical concerns were included in this analysis. RESULTS: A total of 520, 155, and 320 subjects were assigned to receive NEMO-500MG, NEMO-750MG, and LEVO, respectively. The incidence of adverse events (AEs) was the highest (54.8%) in the NEMO-750MG group (NEMO-500MG, 36.9%; NEMO-750MG, 54.8%; LEVO, 39.7%) and that of drug-related AEs was comparable between the three groups (NEMO-500MG, 22.9%; NEMO-750MG, 31.0%; LEVO, 22.5%). The majority (>80%) of the patients showed mild drug-related AEs and the distribution based on severity was similar between the groups. The most commonly reported drug-related AEs included neutropenia (NEMO-500MG, 2.5%; NEMO-750MG, 8.4%; LEVO, 4.4%), nausea (NEMO-500MG, 2.5%; NEMO-750MG, 7.1%; LEVO, 2.5%), leukopenia (NEMO-500MG, 2.3%; NEMO-750MG, 4.5%; LEVO, 3.1%), and increased alanine aminotransferase level (NEMO-500MG, 4.4%; NEMO-750MG, 0%; LEVO, 2.5%). CONCLUSION: Nemonoxacin was well tolerated and no clinically significant safety concerns were identified, suggesting that it possesses a desirable safety and tolerability profile similar to that of levofloxacin, and may be a suitable alternative to fluoroquinolones for treating patients with CAP.

Safety and efficacy of oral nemonoxacin versus levofloxacin in treatment of community-acquired pneumonia: A phase 3, multicenter, randomized, double-blind, double-dummy, active-controlled, non-inferiority trial.

BACKGROUND/PURPOSE: Nemonoxacin is a novel nonfluorinated quinolone with excellent in vitro activity against most pathogens in community-acquired pneumonia (CAP), especially Gram-positive isolates. The purpose of this study was to assess the efficacy and safety of nemonoxacin compared with levofloxacin in patients with CAP. METHODS: A phase 3, multicenter, randomized (2:1) controlled trial was conducted in adult CAP patients receiving nemonoxacin 500 mg or levofloxacin 500 mg orally once daily for 7-10 days. Clinical, microbiological response and adverse events were assessed. Non-inferiority was determined in terms of clinical cure rate of nemonoxacin compared with that of levofloxacin in a modified intention-to-treat (mITT) population. NCT registration number: NCT01529476. RESULTS: A total of 527 patients were randomized and treated with nemonoxacin (n = 356) or levofloxacin (n = 171). The clinical cure rate at test-of-cure visit was 94.3% (300/318) for nemonoxacin and 93.5% (143/153) for levofloxacin in the mITT population [difference (95% CI), 0.9% (-3.8%, 5.5%)]. The microbiological success rate was 92.1% (105/114) for nemonoxacin and 91.7% (55/60) for levofloxacin in the bacteriological mITT population [difference (95% CI), 0.4% (-8.1%, 9.0%)]. The incidence of adverse events (AEs) was comparable between nemonoxacin (33.1%, 118/356) and levofloxacin (33.3%, 57/171) (P > 0.05). CONCLUSION: Nemonoxacin 500 mg once daily for 7-10 days is as effective and safe as levofloxacin for treating adult CAP patients in terms of clinical cure rates, microbiological success rates, and safety profile. ClinicalTrials.gov identifier: NCT01529476.

Modulation effects of the East Asian winter monsoon on El Niño-related rainfall anomalies in southeastern China.

The present study investigates the modulation of the East Asian winter monsoon (EAWM) in the impacts of El Niño on the wintertime rainfall anomalies in southeastern China. Here, the variability of the EAWM that is independent of ENSO is considered, which is referred to as EAWMres with a strong EAWMres denoting anomalous northerly winds. Results demonstrate that strong (weak) EAWMres weakens (enhances) the positive rainfall anomalies in southeastern China induced by El Niño, because anomalous downward motion over the western North Pacific (WNP) associated with El Niño is weakened (strengthened) by strong (weak) EAWMres. The modulated convective activity over the WNP, on the one hand, changes the anomalous local Hadley circulation associated with El Niño. When El Niño is combined with strong (weak) EAWMres, anomalous local Hadley circulation is weak (strong) and the resultant anomalous upward motion is weak (strong) over southeastern China, leading to small (larger) positive rainfall anomalies there. On the other hand, the modulated WNP convective activity induces different low-level atmospheric responses to El Niño. During an El Niño winter with strong (weak) EAWMres, the weak (strong) anomalous suppressed convection produces a weak (strong) and insignificant (significant) anomalous low-level WNP anticyclone, resulting in correspondingly insignificant (significant) rainfall anomalies in southeastern China. Results from a linear baroclinic model further suggest that the different low-level atmospheric responses over WNP are mainly induced by different diabatic heating associated with El Niño under different EAWMres conditions.

Previous antibiotic exposure and evolution of antibiotic resistance in mechanically ventilated patients with nosocomial infections.

PURPOSE: This study aimed to evaluate the impact of previous antibiotic exposure and the influence of time interval since exposure on the evolution of antibiotic-resistant infections. METHODS: We retrospectively analyzed 167 mechanically ventilated patients with nosocomial infections over a 3-year period, with focus on infections in the bloodstream, urinary tract, lower respiratory tract, and surgical sites. RESULTS: Of 167 patients, 62% were confirmed as antibiotic resistant. The most common isolated pathogen was extended-spectrum ß-lactamase Enterobacteriaceae (43.9%), followed by methicillin-resistant Staphylococcus aureus (22.8%), and carbapenem-resistant Acinetobacter baumannii (17.5%). Multivariate analysis revealed that the association between resistance and the time interval increased within 10 days (odds ratio [OR], 2.45; P=.133) and peaked at 11 to 20 days (OR, 7.17; P=.012). The data were categorized into 2 groups: when the time interval was more than 20 days, there was a 23.9% reduction in resistance rate compared with when the time interval was 20 days or less (OR, 0.36; P=.002). CONCLUSIONS: Although antibiotic exposure increased resistance rate in nosocomial infections, this association decreased as time interval increased. Antibiotic stewardship should consider the significance of time interval while investigating the evolution of subsequent antibiotic-resistant infections.

Efficacy and safety of nemonoxacin versus levofloxacin for community-acquired pneumonia.

Nemonoxacin, a novel nonfluorinated quinolone, exhibits potent in vitro and in vivo activities against community-acquired pneumonia (CAP) pathogens, including multidrug-resistant Streptococcus pneumoniae. Patients with mild to moderate CAP (n = 265) were randomized to receive oral nemonoxacin (750 mg or 500 mg) or levofloxacin (500 mg) once daily for 7 days. Clinical responses were determined at the test-of-cure visit in intent-to-treat (ITT), clinical per protocol (PPc), evaluable-ITT, and evaluable-PPc populations. The clinical cure rates for 750 mg nemonoxacin, 500 mg nemonoxacin, and levofloxacin were 89.9%, 87.0%, and 91.1%, respectively, in the evaluable-ITT population; 91.7%, 87.7%, and 90.3%, respectively, in the evaluable-PPc population; 82.6%, 75.3%, and 80.0%, respectively, in the ITT population; and 83.5%, 78.0%, and 82.3%, respectively, in the PPc population. Noninferiority to levofloxacin was demonstrated in both the 750-mg and 500-mg nemonoxacin groups for the evaluable-ITT and evaluable-PPc populations, and also in the 750 mg nemonoxacin group for the ITT and PPc populations. Overall bacteriological success rates were high for all treatment groups in the evaluable-bacteriological ITT population (90.2% in the 750 mg nemonoxacin group, 84.8% in the 500 mg nemonoxacin group, and 92.0% in the levofloxacin group). All three treatments were well tolerated, and no drug-related serious adverse events were observed. Overall, oral nemonoxacin (both 750 mg and 500 mg) administered for 7 days resulted in high clinical and bacteriological success rates in CAP patients. Further, good tolerability and excellent activity against common causative pathogens were demonstrated. Nemonoxacin (750 mg and 500 mg) once daily is as effective and safe as levofloxacin (500 mg) once daily for the treatment of CAP.

Mortality and readmission among ventilator-dependent patients after successful weaned discharge from a respiratory care ward.

BACKGROUND/PURPOSE: Patients on prolonged mechanical ventilation in Taiwan are stepped down to a respiratory care ward (RCW) for further respiratory care. Only a few patients in the RCW can ultimately be weaned and discharged. In this study, we tried to determine factors that predict mortality and readmission of these patients in the post-discharge period. METHODS: Between May 1, 2004 and October 31, 2006, clinical data were retrospectively analyzed for eligible patients in a RCW. Patients who were successfully weaned from mechanical ventilation were enrolled in this study. RESULTS: A total of 243 patients were eligible for evaluation, and 67 patients were successfully weaned and discharged. By Kaplan-Meier curve, 36 (67.1%) patients were readmitted within 3 months after discharge, and among these, 23 (63.9%) had mechanical ventilation reinstituted at the time of first readmission. The most common cause of readmission was airway infection (80.5%). Overall mortality and readmission rates at 1 year after weaned discharge were 32.9% and 88.2%, respectively. By multivariate analysis, patients with neurologic causes of ventilator dependency were less likely to be readmitted (hazard ratio = 0.36; p =0.034), and neoplastic diseases (hazard ratio = 4.66; p =0.031) were independently associated with mortality. CONCLUSION: Underlying comorbidities and causes of ventilator dependency are important predictors of mortality and readmission among patients after weaned discharge from a RCW.