This study explored spatial explicit multiple cropping efficiency （MCE） of China in 2005 by coupling time series remote sensing data with an econometric model - stochastic frontier analysis （SFA）. We firstly extra...This study explored spatial explicit multiple cropping efficiency （MCE） of China in 2005 by coupling time series remote sensing data with an econometric model - stochastic frontier analysis （SFA）. We firstly extracted multiple cropping index （MCI） on the basis of the close relationship between crop phenologies and moderate-resolution imaging spectroradiometer （MODIS） enhanced vegetation index （EVI） value. Then, SFA model was employed to calculate MCE, by considering several indicators of meteorological conditions as inputs of multiple cropping systems and the extracted MCI was the output. The result showed that 46% of the cultivated land in China in 2005 was multiple cropped, including 39% double- cropped land and 7% triple-cropped land. Most of the multiple cropped land was distributed in the south of Great Wall. The total efficiency of multiple cropping in China was 87.61% in 2005. Southwestern China, Ganxin Region, the middle and lower reaches of Yangtze River and Huanghuaihai Plain were the four agricultural zones with the largest rooms for increasing MCI and improving MCE. Fragmental terrain, soil salinization, deficiency of water resources, and loss of labor force were the obstacles for MCE promotion in different zones. The method proposed in this paper is theoretically reliable for MCE extraction, whereas further studies are need to be done to investigate the most proper indicators of meteorological conditions as the inputs of multiple cropping systems.展开更多
目的了解中国18~64岁成年居民膳食能量密度与中心性肥胖的关联性,为今后中国人群中心性肥胖的精准防控提供科学依据。方法本研究数据来源于2018年中国健康与营养调查项目。采用分层多阶段整群随机抽样方法,选取18~64岁成年居民9278名作...目的了解中国18~64岁成年居民膳食能量密度与中心性肥胖的关联性,为今后中国人群中心性肥胖的精准防控提供科学依据。方法本研究数据来源于2018年中国健康与营养调查项目。采用分层多阶段整群随机抽样方法,选取18~64岁成年居民9278名作为研究对象。采用连续3 d 24 h膳食回顾法结合家庭食物称重法收集研究对象膳食数据信息并计算其膳食能量密度。应用SAS 9.4统计软件进行χ^(2)检验、趋势性检验、Kruskal-Wallis秩和检验、Dwass-Steel-Critchlow-Fligner法两两比较、多因素logistic回归分析。结果男、女性研究对象的能量、碳水化合物的摄入量均随膳食能量密度水平的升高而上升;男、女性最高四分位膳食能量密度组的蛋白质、脂肪的摄入量均显著高于最低四分位膳食能量密度组,而膳食纤维的摄入量低于最低四分位膳食能量密度组,差异均有统计学意义(P<0.05)。男、女性研究对象食物重量、蔬菜摄入量随膳食能量密度水平的升高而下降;男、女性研究对象食用油的摄入量随膳食能量密度水平的升高而上升;男、女性最高四分位膳食能量密度组的水果、蛋类食物摄入量均低于其他3组,差异均有统计学意义(P<0.05)。多因素logistic回归分析结果显示,与最低四分位膳食能量密度组相比,最高四分位膳食能量密度组女性患中心性肥胖的风险较高(OR=1.280,95%CI:1.085~1.510)。结论18~64岁成年女性居民膳食能量密度与中心性肥胖存在显著的关联性,应有针对性地对该年龄段成年女性进行膳食能量密度相关的健康宣讲。展开更多
基金supported by the National Natural Science Foundation of China (41001277)the National 973 Program of China (2010CB95090102)
文摘This study explored spatial explicit multiple cropping efficiency （MCE） of China in 2005 by coupling time series remote sensing data with an econometric model - stochastic frontier analysis （SFA）. We firstly extracted multiple cropping index （MCI） on the basis of the close relationship between crop phenologies and moderate-resolution imaging spectroradiometer （MODIS） enhanced vegetation index （EVI） value. Then, SFA model was employed to calculate MCE, by considering several indicators of meteorological conditions as inputs of multiple cropping systems and the extracted MCI was the output. The result showed that 46% of the cultivated land in China in 2005 was multiple cropped, including 39% double- cropped land and 7% triple-cropped land. Most of the multiple cropped land was distributed in the south of Great Wall. The total efficiency of multiple cropping in China was 87.61% in 2005. Southwestern China, Ganxin Region, the middle and lower reaches of Yangtze River and Huanghuaihai Plain were the four agricultural zones with the largest rooms for increasing MCI and improving MCE. Fragmental terrain, soil salinization, deficiency of water resources, and loss of labor force were the obstacles for MCE promotion in different zones. The method proposed in this paper is theoretically reliable for MCE extraction, whereas further studies are need to be done to investigate the most proper indicators of meteorological conditions as the inputs of multiple cropping systems.
文摘目的了解中国18~64岁成年居民膳食能量密度与中心性肥胖的关联性,为今后中国人群中心性肥胖的精准防控提供科学依据。方法本研究数据来源于2018年中国健康与营养调查项目。采用分层多阶段整群随机抽样方法,选取18~64岁成年居民9278名作为研究对象。采用连续3 d 24 h膳食回顾法结合家庭食物称重法收集研究对象膳食数据信息并计算其膳食能量密度。应用SAS 9.4统计软件进行χ^(2)检验、趋势性检验、Kruskal-Wallis秩和检验、Dwass-Steel-Critchlow-Fligner法两两比较、多因素logistic回归分析。结果男、女性研究对象的能量、碳水化合物的摄入量均随膳食能量密度水平的升高而上升;男、女性最高四分位膳食能量密度组的蛋白质、脂肪的摄入量均显著高于最低四分位膳食能量密度组,而膳食纤维的摄入量低于最低四分位膳食能量密度组,差异均有统计学意义(P<0.05)。男、女性研究对象食物重量、蔬菜摄入量随膳食能量密度水平的升高而下降;男、女性研究对象食用油的摄入量随膳食能量密度水平的升高而上升;男、女性最高四分位膳食能量密度组的水果、蛋类食物摄入量均低于其他3组,差异均有统计学意义(P<0.05)。多因素logistic回归分析结果显示,与最低四分位膳食能量密度组相比,最高四分位膳食能量密度组女性患中心性肥胖的风险较高(OR=1.280,95%CI:1.085~1.510)。结论18~64岁成年女性居民膳食能量密度与中心性肥胖存在显著的关联性,应有针对性地对该年龄段成年女性进行膳食能量密度相关的健康宣讲。
