In this paper we study the necessary conditions for the masses of the nested regular polygon solutions of the planar 2N-body problem.We prove that the masses at the vertices of each regular polygon must be equal to ea...In this paper we study the necessary conditions for the masses of the nested regular polygon solutions of the planar 2N-body problem.We prove that the masses at the vertices of each regular polygon must be equal to each other.展开更多
This paper studies the status of empty nest only-child families in urban China,using data about these families taken from a 2015 survey conducted by the Institute of Population and Labor Economics,Chinese Academy of S...This paper studies the status of empty nest only-child families in urban China,using data about these families taken from a 2015 survey conducted by the Institute of Population and Labor Economics,Chinese Academy of Social Sciences.Factors that determine the timing of empty nest periods and their duration for only-child parents are also analyzed.The data shows that more than half of the only-child parents surveyed in 2015 lived in empty nests.Some of these parents had been empty-nesters for as many as 25 years.During the life cycle of families,the empty nest status of elderly only-child parents shows different characteristics at different stages,as the only-children begin attending universities,start to work,get married,and have children of their own.There are empty nest periods in only-child families when the only-child leaves the parents for several years and periods when the child returns home and lives with parents for years.The living arrangements of only-child parents depend mainly on changes in the life needs of their only-children.Intergenerational support is focused on meeting the needs of only-children.展开更多
基金This work was supported by the National Natural Science Foundation of China (Grant No. 19871096), QSSTE and MOST.
文摘In this paper we study the necessary conditions for the masses of the nested regular polygon solutions of the planar 2N-body problem.We prove that the masses at the vertices of each regular polygon must be equal to each other.
文摘This paper studies the status of empty nest only-child families in urban China,using data about these families taken from a 2015 survey conducted by the Institute of Population and Labor Economics,Chinese Academy of Social Sciences.Factors that determine the timing of empty nest periods and their duration for only-child parents are also analyzed.The data shows that more than half of the only-child parents surveyed in 2015 lived in empty nests.Some of these parents had been empty-nesters for as many as 25 years.During the life cycle of families,the empty nest status of elderly only-child parents shows different characteristics at different stages,as the only-children begin attending universities,start to work,get married,and have children of their own.There are empty nest periods in only-child families when the only-child leaves the parents for several years and periods when the child returns home and lives with parents for years.The living arrangements of only-child parents depend mainly on changes in the life needs of their only-children.Intergenerational support is focused on meeting the needs of only-children.
