Supported by MSS images in the mid and late 1970s, TM images in the early 1990s and TM/ETM images in 2004, grassland degradation in the "Three-River Headwaters" region (TRH region) was interpreted through analysis on RS images in two time series, then the spatial and temporal characteristics of grassland degradation in the TRH region were analyzed since the 1970s. The results showed that grassland degradation in the TRH region was a continuous change process which had large affected area and long time scale, and rapidly strengthen phenomenon did not exist in the 1990s as a whole. Grassland degradation pattern in the TRH region took shape initially in the mid and late 1970s. Since the 1970s, this degradation process has taken place continuously, obviously characterizing different rules in different regions. In humid and semi-humid meadow region, grassland firstly fragmentized, then vegetation coverage decreased continuously, and finally "black-soil-patch" degraded grassland was formed. But in semi-arid and arid steppe region, the vegetation coverage decreased continuously, and finally desertification was formed. Because grassland degradation had obviously regional differences in the TRH region, it could be regionalized into 7 zones, and each zone had different characteristics in type, grade, scale and time process of grassland degradation.

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Background: Virtual reality (VR) is an innovation that permits the individual to discover and operate within threedimensional (3D) environment to gain practical understanding. This research aimed to examine the general efficiency of VR for teaching medical anatomy. Methods: We executed a meta-analysis of randomized controlled studies of the performance of VR anatomy education. We browsed five databases from the year 1990 to 2019. Ultimately, 15 randomized controlled trials with a teaching outcome measure analysis were included. Two authors separately chose studies, extracted information, and examined the risk of bias. The primary outcomes were examination scores of the students. Secondary outcomes were the degrees of satisfaction of the students. Random-effects models were used for the pooled evaluations of scores and satisfaction degrees. Standardized mean difference (SMD) was applied to assess the systematic results. The heterogeneity was determined by I 2 statistics, and then was investigated by meta-regression and subgroup analyses. Results: In this review, we screened and included fifteen randomized controlled researches (816 students). The pooled analysis of primary outcomes showed that VR improves test scores moderately compared with other approaches (standardized mean difference [SMD] = 0.53; 95% Confidence Interval [CI] 0.09-0.97, p < 0.05; I 2 = 87.8%). The high homogeneity indicated that the studies were different from each other. Therefore, we carried out metaregression as well as subgroup analyses using seven variables (year, country, learners, course, intervention, comparator, and duration). We found that VR improves post-intervention test score of anatomy compared with other types of teaching methods. Conclusions: The finding confirms that VR may act as an efficient way to improve the learners' level of anatomy knowledge. Future research should assess other factors like degree of satisfaction, cost-effectiveness, and adverse reactions when evaluating the teaching effectiveness of VR in anatomy.

Inter-annual dynamics of grassland yield of the Three Rivers Headwaters Region of Qinghai-Tibet Plateau of China in 1988-2005 was analyzed using the GLO-PEM model, and the herbage supply function was evaluated. The results indicate that while grassland yield in the region showed marked inter-annual fluctuation there was a trend of increased yield over the 18 years of the study. This increase was especially marked for Alpine Desert and Alpine Steppe and in the west of the region. The inter-annual coefficient of variation of productivity increased from the east to the west of the region and from Marsh, Alpine Meadow, Alpine Steppe, Temperate Steppe to Alpine Desert grasslands. Climate change, particularly increased temperatures in the region during the study period, is suggested to be the main cause of increased grassland yield. However, reduced grazing pressure and changes to the seasonal pattern of grazing could also have influenced the grassland yield trend. These findings indicate the importance of understanding the function of the grassland ecosystems in the region and the effect of climate change on them especially in regard to their use to supply forage for animal production. Reduction of grazing pressure, especially during winter, is indicated to be critical for the restoration and sustainable use of grassland ecosystems in the region.