目的:探索云南省不同环境类型新发钉螺孳生地的时空分布规律。方法:收集整理1950-2014年云南省螺情数据(来自云南省地方病防治所),建立新发钉螺孳生地分布的时空数据库,采用空间自相关分析和扫描统计量分析方法探索不同环境类型(沟渠、...目的:探索云南省不同环境类型新发钉螺孳生地的时空分布规律。方法:收集整理1950-2014年云南省螺情数据(来自云南省地方病防治所),建立新发钉螺孳生地分布的时空数据库,采用空间自相关分析和扫描统计量分析方法探索不同环境类型(沟渠、塘堰、水田、旱地、滩地、其他环境)新发钉螺孳生地的时空分布规律。结果:1950-2014年,云南省年新发钉螺孳生地数量在1955年达到峰值(1 730个),其后呈现波动下降趋势。1993-2014年新发钉螺孳生地数量主要维持在100个以下,仅2004、2013年分别上升至160、131个。滩地环境新发钉螺孳生地的平均持续存在时间最长,为43.85年;其次是水田环境,为37.01年;塘堰环境的平均持续存在时间最短,为20.44年。空间自相关分析显示,不同环境类型新发钉螺孳生地的持续存在时间均具有空间正相关性(全局莫兰指数为0.43~0.64,均 P < 0.05);扫描统计量分析显示,不同环境类型新发钉螺孳生地均具有时空聚集性(均 P < 0.001),分别探测出3~6个聚集簇。 结论:云南省不同环境类型新发钉螺孳生地均具有时空聚集性,对不同环境类型聚集区域需加强监测与防控,防止螺情进一步扩散。展开更多
This paper studies a class of forward-backward stochastic differential equations (FBSDE)in a general Markovian framework.The forward SDE represents a large class of strong Markov semimartingales,and the backward gener...This paper studies a class of forward-backward stochastic differential equations (FBSDE)in a general Markovian framework.The forward SDE represents a large class of strong Markov semimartingales,and the backward generator requires only mild regularity assumptions.The authors showthat the Four Step Scheme introduced by Ma,et al.(1994) is still effective in this case.Namely,the authors show that the adapted solution of the FBSDE exists and is unique over any prescribedtime duration;and the backward components can be determined explicitly by the forward componentvia the classical solution to a system of parabolic integro-partial differential equations.An importantconsequence the authors would like to draw from this fact is that,contrary to the general belief,in aMarkovian set-up the martingale representation theorem is no longer the reason for the well-posednessof the FBSDE,but rather a consequence of the existence of the solution of the decoupling integralpartialdifferential equation.Finally,the authors briefly discuss the possibility of reducing the regularityrequirements of the coefficients by using a scheme proposed by F.Delarue (2002) to the current case.展开更多
文摘目的:探索云南省不同环境类型新发钉螺孳生地的时空分布规律。方法:收集整理1950-2014年云南省螺情数据(来自云南省地方病防治所),建立新发钉螺孳生地分布的时空数据库,采用空间自相关分析和扫描统计量分析方法探索不同环境类型(沟渠、塘堰、水田、旱地、滩地、其他环境)新发钉螺孳生地的时空分布规律。结果:1950-2014年,云南省年新发钉螺孳生地数量在1955年达到峰值(1 730个),其后呈现波动下降趋势。1993-2014年新发钉螺孳生地数量主要维持在100个以下,仅2004、2013年分别上升至160、131个。滩地环境新发钉螺孳生地的平均持续存在时间最长,为43.85年;其次是水田环境,为37.01年;塘堰环境的平均持续存在时间最短,为20.44年。空间自相关分析显示,不同环境类型新发钉螺孳生地的持续存在时间均具有空间正相关性(全局莫兰指数为0.43~0.64,均 P < 0.05);扫描统计量分析显示,不同环境类型新发钉螺孳生地均具有时空聚集性(均 P < 0.001),分别探测出3~6个聚集簇。 结论:云南省不同环境类型新发钉螺孳生地均具有时空聚集性,对不同环境类型聚集区域需加强监测与防控,防止螺情进一步扩散。
基金supported by the National Science Foundation under Grant Nos. #DMS 0505472, 0806017,and#DMS 0604309
文摘This paper studies a class of forward-backward stochastic differential equations (FBSDE)in a general Markovian framework.The forward SDE represents a large class of strong Markov semimartingales,and the backward generator requires only mild regularity assumptions.The authors showthat the Four Step Scheme introduced by Ma,et al.(1994) is still effective in this case.Namely,the authors show that the adapted solution of the FBSDE exists and is unique over any prescribedtime duration;and the backward components can be determined explicitly by the forward componentvia the classical solution to a system of parabolic integro-partial differential equations.An importantconsequence the authors would like to draw from this fact is that,contrary to the general belief,in aMarkovian set-up the martingale representation theorem is no longer the reason for the well-posednessof the FBSDE,but rather a consequence of the existence of the solution of the decoupling integralpartialdifferential equation.Finally,the authors briefly discuss the possibility of reducing the regularityrequirements of the coefficients by using a scheme proposed by F.Delarue (2002) to the current case.
