Modeling Arctic Boundary Layer Cloud Streets at Grey-zone Resolutions

To better understand how model resolution affects the formation of Arctic boundary layer clouds,we investigated the influence of grid spacing on simulating cloud streets that occurred near Utqiaġvik(formerly Barrow),Alaska,on 2 May 2013 and were observed by MODIS(the Moderate Resolution Imaging Spectroradiometer).The Weather Research and Forecasting model was used to simulate the clouds using nested domains with increasingly fine resolution ranging from a horizontal grid spacing of 27 km in the boundary-layer-parameterized mesoscale domain to a grid spacing of 0.111 km in the large-eddy-permitting domain.We investigated the model-simulated mesoscale environment,horizontal and vertical cloud structures,boundary layer stability,and cloud properties,all of which were subsequently used to interpret the observed roll-cloud case.Increasing model resolution led to a transition from a more buoyant boundary layer to a more shear-driven turbulent boundary layer.The clouds were stratiform-like in the mesoscale domain,but as the model resolution increased,roll-like structures,aligned along the wind field,appeared with ever smaller wavelengths.A stronger vertical water vapor gradient occurred above the cloud layers with decreasing grid spacing.With fixed model grid spacing at 0.333 km,changing the model configuration from a boundary layer parameterization to a large-eddy-permitting scheme produced a more shear-driven and less unstable environment,a stronger vertical water vapor gradient below the cloud layers,and the wavelengths of the rolls decreased slightly.In this study,only the large-eddy-permitting simulation with gird spacing of 0.111 km was sufficient to model the observed roll clouds.

Lowering the threshold of alanine aminotransferase for enhanced identification of significant hepatic injury in chronic hepatitis B patients

BACKGROUND The clinical and histological features of chronic hepatitis B(CHB)patients who fall into the"grey zone(GZ)"and do not fit into conventional natural phases are unclear.AIM To explore the impact of varying the threshold of alanine aminotransferase(ALT)levels in identifying significant liver injury among GZ patients.METHODS This retrospective analysis involved a cohort of 1617 adult patients diagnosed with CHB who underwent liver biopsy.The clinical phases of CHB patients were determined based on the European Association for the Study of the Liver 2017 Clinical Practice Guidelines.GZ CHB patients were classified into four groups:GZ-A(HBeAg positive,normal ALT levels,and HBV DNA≤10^(7) IU/mL),GZ-B(HBeAg positive,elevated ALT levels,and HBV DNA<10^(4) or>10^(7) IU/mL),GZC(HBeAg negative,normal ALT levels,and HBV DNA≥2000 IU/mL),and GZ-D(HBeAg negative,elevated ALT levels,and HBV DNA≤2000 IU/mL).Significant hepatic injury(SHI)was defined as the presence of notable liver inflammation(≥G2)and/or significant fibrosis(≥S2).RESULTS The results showed that 50.22%of patients were classified as GZ,and 63.7%of GZ patients developed SHI.The study also found that lowering the ALT treatment thresholds to the American Association for the Study of Liver Diseases 2018 treatment criteria(35 U/L for men and 25 U/L for women)can more accurately identify patients with significant liver damage in the GZ phases.In total,the proportion of patients with ALT≤40 U/L who required antiviral therapy was 64.86%[(221+294)/794].When we lowered the ALT treatment threshold to the new criteria(30 U/L for men and 19 U/L for women),the same outcome was revealed,and the proportion of patients with ALT≤40 U/L who required antiviral therapy was 75.44%[(401+198)/794].Additionally,the proportion of SHI was 49.1%in patients under 30 years old and increased to 55.3%in patients over 30 years old(P=0.136).CONCLUSION These findings suggest the importance of redefining the natural phases of CHB and using new ALT treatment thresholds for better diagnosis and management of CHB patients in the GZ phases.