[Temporal and spatial variations of soil moisture in North China]. / 华北地区土壤水分的时空变化特征.

Soil moisture is an important hydrological parameter and a basic element for research in water cycle and climate change. Using hourly recorded soil moisture data of 374 stations from the new generation of automatic soil moisture encryption observation network constructed by China Meteo-rological Administration, we analyzed the spatial and temporal variations of soil moisture in North China from 2013 to 2019 and the relationship with precipitation and temperature. The results showed that soil moisture in 10-100 cm layer decreased fluctuatly as a whole, with the decreasing at the 100 cm being serious. The spatial distribution of soil moisture at different depths was characterized by high in the southeast and low in the northwest. About 63% of the surface layer was short of moisture. Soil moisture at different depths changed significantly with the seasons. In summer, soil moisture of each layer reached the highest and soil entropy of each layer was suitable, while it reached a low point in spring. Soil moisture was closely correlated with precipitation and temperature, but the correlation got weaker gradually with the increase of soil depth. Soil moisture was more sensitive to precipitation than to temperature.

Trans-cranial Doppler predicts early neurologic deterioration in anterior circulation ischemic stroke after successful endovascular treatment.

BACKGROUND: Early neurologic deterioration (END) may occur in patients with anterior circulation ischemic stroke (ACIS) after receiving endovascular treatment (EVT). Hemodynamic insufficiency, re-occlusion, and post-re-canalization hyper-perfusion are likely to play a critical role in END. We hypothesized that hemodynamic changes can predict END in patients with ACIS post-successful EVT using trans-cranial Doppler (TCD). METHODS: We utilized a prospectively maintained database of ACIS patients treated with EVT between September 2016 and June 2018 in the Xuanwu Hospital, Capital Medical University. TCD parameters including peak systolic velocity (PSV), bilateral mean flow velocity (MFV), and pulse index (PI) were determined via the middle cerebral arteries within 72 h post-EVT. A logistic regression model was applied to detect independent predictors for END. RESULTS: Totally, 112 EVT patients were included in this study and 80/112 patients experienced successful re-canalization with <50% residual stenosis, while 17/80 (21.3%) patients suffered END, for which vasogenic cerebral edema (11/17) was considered as a leading role and followed by symptomatic intra-cranial hemorrhage (4/17) and ischemia progression (2/17). For the 80 patients, the PSV (median: 127 cm/s vs. 116 cm/s, P = 0.039), the ratio of ipsilateral-MFV/contra-lateral-MFV (iMFV/cMFV) (median: 1.29 vs. 1.02, P = 0.036) and iMFV/mean blood pressure (MBP) (median: 0.97 vs. 0.79, P = 0.008) in END patients were higher than those of non-END. Using the receiver-operating characteristic curve to obtain cut-off values for PSV, PI, iMFV/cMFV, and iMFV/MBP for END, we found that PI ≥0.85 (odds ratio: 11.03, 95% confidence interval: 1.92-63.46, P = 0.007) and iMFV/MBP ≥0.84 (odds ratio: 9.20, 95% confidence interval: 2.07-40.84, P = 0.004) were independent predictors of END in a multivariate logistic regression model, with a sensitivity of 82.4% and 76.5% and a specificity of 42.9% and 66.7%, respectively, and had the positive predictive values of 29.0% and 38.2%, and negative predictive values of 90.0% and 91.3%, with an area under the receiver-operating characteristic curve of 0.57 and 0.71, respectively. CONCLUSION: TCD examination of EVT patients may be used as a real-time tool to detect END predictors, such as the higher PI and iMFV/MBP, allowing for better post-thrombectomy management in ACIS patients.

Early Neurological Deterioration after Recanalization Treatment in Patients with Acute Ischemic Stroke: A Retrospective Study.

BACKGROUND: Early neurological deterioration (END) is a prominent issue after recanalization treatment. However, few studies have reported the characteristics of END after endovascular treatment (EVT) as so far. This study investigated the incidence, composition, and outcomes of END after intravenous recombinant tissue plasminogen activator (IV rt-PA) and EVT of acute ischemic stroke, and identified risk factors for END. METHODS: Medical records of patients who received recanalization treatment between January 1, 2014, and December 31, 2015 were reviewed. Patients were classified into IV rt-PA or EVT group according to the methods of recanalization treatment. The END was defined as an increase in the National Institutes of Health Stroke Scale (NIHSS) ≥4 or an increase in Ia of NIHSS ≥1 within 72 h after recanalization treatment. Clinical data were compared between the END and non-END subgroups within each recanalization group. RESULTS: Of the 278 patients included in the study, the incidence of END was 34.2%. The incidence rates of END were 29.8% in the IV rt-PA group and 40.2% in the EVT group. Ischemia progression (68.4%) was the main contributor to END followed by vasogenic cerebral edema (21.1%) and symptomatic intracranial hemorrhage (10.5%). Multivariate logistic regression showed that admission systolic blood pressure (SBP) ≥160 mmHg (odds ratio [OR]: 2.312, 95% confidence interval [CI]: 1.105-4.837) and large artery occlusion after IV rt-PA (OR: 3.628, 95% CI: 1.482-8.881) independently predicted END after IV rt-PA; and admission SBP ≥140 mmHg (OR: 5.183, 95% CI: 1.967-13.661), partial recanalization (OR: 4.791, 95% CI: 1.749-13.121), and nonrecanalization (OR: 5.952, 95% CI: 1.841-19.243) independently predicted END after EVT. The mortality rate and grave outcome rate at discharge of all the END patients (26.3% and 55.8%) were higher than those of all the non-END patients (1.1% and 18.6%; P < 0.01). CONCLUSIONS: END was not an uncommon event and associated with death and grave outcome at discharge. High admission SBP and unsatisfactory recanalization of occluded arteries might predict END.

[An operational remote sensing algorithm of land surface evapotranspiration based on NOAA PAL dataset].

Based on the time series 10-day composite NOAA Pathfinder AVHRR Land (PAL) dataset (8 km x 8 km), and by using land surface energy balance equation and "VI-Ts" (vegetation index-land surface temperature) method, a new algorithm of land surface evapotranspiration (ET) was constructed. This new algorithm did not need the support from meteorological observation data, and all of its parameters and variables were directly inversed or derived from remote sensing data. A widely accepted ET model of remote sensing, i. e., SEBS model, was chosen to validate the new algorithm. The validation test showed that both the ET and its seasonal variation trend estimated by SEBS model and our new algorithm accorded well, suggesting that the ET estimated from the new algorithm was reliable, being able to reflect the actual land surface ET. The new ET algorithm of remote sensing was practical and operational, which offered a new approach to study the spatiotemporal variation of ET in continental scale and global scale based on the long-term time series satellite remote sensing images.

[Regional evapotranspiration of different land covers based on remote sensing].

In this paper, surface energy balance system (SEBS) was extended into a regional daily evapotranspiration (ET) estimation model based on remote sensing data, and the extended SEBS was applied to estimate the regional daily ET of Huanghe-Huaihe-Haihe rivers region in Northern China Plain by using MODIS/TERRA data. An analysis was made on the estimated daily ET characteristics of different land covers in the study area by using the spatial analysis module of ArcGIS. Since there were no field observations of ET on each land cover, the estimated daily ET of different land covers was compared with each other, taking the data on April 17, 2001 as an example. The results showed that the regional daily ET estimated by SEBS was reasonable. Wetland and cultivated land had the highest daily ET value, followed by forest-, bush- and grassland, and waste land. The characteristics of the daily ET over these land covers were accorded with the existing knowledge of ET over this region, and coincident to the results of previous work in this area. It was interesting that the residential area also had a higher ET value, which was explained as the higher ET of the land use types, e. g. , water body, street trees, and grass parcels in the resident areas within the pixel scale. The spatial inhomogeneity of ET among the forest-, bush-, grass- and cultivated land covers were caused by the spatial inhomogeneous soil water content under these land covers, and the spatial inhomogeneity of ET over cultivated land could be a potential indicator of making reasonable and effective irrigation schedule for the farmland. The limitations of using SEBS model in daily ET estimation were discussed, especially the possibility of underestimating the ET over water body and wetland covers due to the unsuitable surface parameterization scheme for these land types in the model.