ABSTRACT
With global climate change, changes in vegetation phenology have become increasingly evident. Horqin Sandy Land is located near the eastern part of the West Liaohe River. It is the largest sandy land in China and its ecological environment is fragile. Investigating the changes in vegetation phenology in these sandy areas and determining the relationship between vegetation phenology and meteorological factors are of great importance for predicting the impacts of future climate change and understanding the response mechanisms of ecosystems. In this study, we used the time series of the Normalized Difference Vegetation Index (NDVI) from 2000 to 2021 and extracted the vegetation phenology in the Horqin Sandy Land using high-order curve fitting methods, including the start date of the growing season (SOS), the end date of the growing season (EOS), and the length of the growing season (LOS). We analyzed their temporal variation and used partial correlation analysis to determine their relationship with meteorological factors (temperature and precipitation). In addition, we compared the phenology and microclimate of forest and grassland within the study area. In the Horqin Sandy Land, the vegetation SOS was concentrated between the 115th and 150th day, the EOS was concentrated between the 260th and 305th day, and the LOS ranged from 125 to 190 days. Over the past 22 years, the SOS, EOS, and LOS of vegetation in the Horqin Sandy Land showed trends of delay, shift, and extension, with rates of change of 0.82 d/10a, 5.82 d/10a, and 5.00 d/10a, respectively. The start date of the growing season in the Horqin Sandy Land was mainly influenced by precipitation in April of the current year, while the end date was mainly influenced by precipitation in August of the current year. Overall, the SOS in the forested areas of the Horqin Sandy Land was slightly later than in the grasslands, but the EOS in the forested areas was significantly later than in the grasslands, resulting in a longer LOS in the forests. In addition, annual precipitation and the rate of precipitation increase were higher in the forested areas than in the grasslands, but soil temperature was higher in the grasslands than in the forests. Vegetation phenology in the Horqin Sandy Land has undergone significant changes, mainly manifested in the delayed end date of the growing season, the extended length of the growing season, and the differences between forest and grassland. This indicates that climate change has indeed affected phenological changes and provides a theoretical basis for subsequent ecological restoration and desertification prevention efforts in the region.
ABSTRACT
OBJECTIVES: Tirofiban is widely used in clinical practice for acute ischemic stroke (AIS). However, whether tirofiban increases the bleeding risk or improves the outcome of AIS patients with endovascular treatment (ET) is unknown. The aim of this meta-analysis is to evaluate the safety and efficacy of tirofiban compared with those without tirofiban in AIS patients receiving ET. METHODS: Systematic literature search was done in PubMed and EMBASE databases without language or time limitation. Safety outcomes were symptomatic intracranial hemorrhage (sICH) and mortality. Efficacy outcomes were recanalization rate and favorable functional outcome. Review Manager 5.3 and Stata Software Package 15.0 were used to perform the meta-analysis. RESULTS: Eleven studies with a total of 2,028 patients were included. A total of 704 (34.7%) patients were administrated tirofiban combined with ET. Meta-analysis suggested that tirofiban did not increase the risk of sICH (odds ratio (OR) 1.08; 95% confidence interval (CI) 0.81-1.46; p = 0.59) but significantly decreased mortality (OR 0.68; 95% CI 0.52-0.89; p = 0.005). There was no association between tirofiban and recanalization rate (OR 1.26; 95% CI 0.86-1.82; p = 0.23) or favorable functional outcome (OR 1.21; 95% CI 0.88-1.68; p = 0.24). Subgroup analyses indicated that preoperative tirofiban significantly increase recanalization rate (OR 3.89; 95% CI 1.70-8.93; p = 0.001) and improve favorable functional outcome (OR 2.30; 95% CI 1.15-4.60; p = 0.02). CONCLUSIONS: Tirofiban is safe in AIS patients with ET and can significantly reduce mortality; preoperative tirofiban may be effective, but further studies are needed to confirm the efficacy.
