Evaluating spray drift from Uncrewed Aerial Spray Systems: A machine learning and variance-based sensitivity analysis of environmental and spray system parameters.

Uncrewed Aerial Spray Systems (UASS), commonly called drones, have become an important application technique for plant protection products in Asia and worldwide. As such, environmental variables and spray system parameters influencing spray drift deserve detailed investigations. This study presents the data analysis of 114 UASS drift trials conducted between December 2021 and December 2022 in China. Study design was based on the ISO 22866:2005 protocol for spray drift trials and considered different UASS platforms, nozzles, and release heights, and specifically continuously measured weather conditions. The relative importance of the environmental variables and spray system parameters was evaluated by a random forest (RF) feature importance analysis, a Sobol sensitivity analysis and partial dependence plots. This approach was preferred to linear ranking techniques such as ANOVA (analysis of variance) due to the non-linearity of the system. In addition, partial dependence plots are proposed to visualize the relationship between specific input parameters within the system. Drift deposition curves calculated from the 114 trials show good agreement with previous UASS trials reported in the literature. As reported in previous studies, spray drift following UASS applications is lower than for manned aerial vehicles, greater than for ground spray applications, and similar to drift observed from orchard air blast applications. In addition, 9 trials were conducted on corn fields in order to evaluate the potential effect of crop cover on spray drift. Spray drift was observed to be reduced over the cropped soil, suggesting that plant cover might possibly reduce spray drift. These findings could help supporting drift mitigation policies, stewardship advice and product labelling around the world.

The agreement and clinical value of hepatic vein pressure gradient and portal vein pressure in patients with portal hypertension / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To evaluate the agreement and correlation between hepatic vein pressure gradient (HVPG) and portal vein pressure (PVP) in patients with portal hypertension,and explore their clinical value.</p><p><b>METHODS</b>A total of 46 patients with portal hypertension were directly measured the free hepatic pressure, wedged hepatic pressure, portal vein pressure before and after TIPS therapy. The agreement and correlation of HVPG and PVP were analyzed, and explore their clinical value.</p><p><b>RESULTS</b>There is no significant agreement or correlation between HVPG and PVP in 5 patients, whose third hilar have large communicating branches between portal vein and Inferior vena cava, or with obvious umbilical vein opened. The HVPGs were significantly agreed with portal vein pressure in other 41 patients. There is no significant difference of HVPG or PVP between earlyTIPS and not early-TIPS groups. In addition, the portal vein pressures after TIPS were significantly decreased compared with that before TIPS.</p><p><b>CONCLUSION</b>The HVPG can well show the PVP except these with obvious communicating branches between portal vein and Inferior vena cava in third hilar, and TIPS can effectively decrease the portal vein pressure in patients with portal hypertension.</p>