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The degradation of the frozen soil in the Qinghai–Tibetan Plateau (QTP) caused by climate warming has attracted extensive worldwide attention due to its significant effects on the ecosystem and hydrological processes. In this study, we propose an effective approach to estimate the spatial distribution and changes in the frozen soil using the moderate-resolution imaging spectroradiometer (MODIS) land surface temperature products as inputs. A comparison with in-situ observations suggests that this method can accurately estimate the mean daily land surface temperature, the spatial distribution of the permafrost, and the maximum thickness of the seasonally-frozen ground in the source region of the Yellow River, located in the northeastern area of the QTP. The results of The Temperature at the Top of the Permafrost model indicates that the area of permafrost in the source region of the Yellow River decreased by 4.82% in the period from 2003 to 2019, with an increase in the areal mean air temperature of 0.35 °C/10 years. A high spatial heterogeneity in the frozen soil changes was revealed. The basin-averaged active layer thickness of the permafrost increased at a rate of 5.46 cm/10 years, and the basin-averaged maximum thickness of the seasonally-frozen ground decreased at a rate of 3.66 cm/10 years. The uncertainties in calculating the mean daily land surface temperature and the soil’s thermal conductivity were likely to influence the accuracy of the estimation of the spatial distribution of the permafrost and the maximum thickness of the seasonally-frozen ground, which highlight the importance of the better integration of field observations and multi-source remote sensing data in order to improve the modelling of frozen soil in the future. Overall, the approach proposed in this study may contribute to the improvement of the application of the MODIS land surface temperature data in the study of frozen soil changes in large catchments with limited in-situ observations in the QTP.

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Background: Combined use of hypnotic and opioids during anesthesia inductions decreases blood pressure. Post-induction hypotension (PIHO) is the most common side effect of anesthesia induction. We aimed to compare the difference in mean arterial pressure (MAP) induced by remimazolam with that induced by etomidate in the presence of fentanyl at tracheal intubation.Methods: We assessed 138 adult patients with American Society of Anesthesiologists physical status I–II who underwent elective urological surgery. Patients were randomly allocated to receive either remimazolam or etomidate as alterative hypnotic in the presence of fentanyl during anesthesia induction. Comparable BIS values were achieved in both groups. The primary outcome was the difference in the MAP at tracheal intubation. The secondary outcomes included the characteristics of anesthesia, surgery, and adverse effects.Results: The MAP was higher in the etomidate group than in the remimazolam group at tracheal intubation (108 [22] mmHg vs. 83 [16] mmHg; mean difference, −26; 95% confidence interval [CI], −33 to −19; p < 0.0001). Heart rate was significantly higher in the etomidate group than in the remimazolam group at tracheal intubation. The patients’ condition warranted the administration of ephedrine more frequently in the remimazolam group (22%) than in the etomidate group (5%) (p = 0.0042) during anesthesia induction. The remimazolam group had a lower incidence of hypertension (0% vs. 9%, p = 0.0133), myoclonus (0% vs. 47%, p < 0.001), and tachycardia (16% vs. 35%, p = 0.0148), and a higher incidence of PIHO (42% vs. 5%, p = 0.001) than the etomidate group during anesthesia induction.Conclusion: Remimazolam was associated with lower MAP and lower heart rate compared to etomidate in the presence of fentanyl at tracheal intubation. Patients in the remimazolam group had a higher incidence of PIHO, and their condition warranted the administration of ephedrine more frequently than in the etomidate group during anesthesia induction.