This study analyzes the relationship between the age of first migration and the probability of repeat migration focusing on rural to urban migrants in China.It is based on the data of the 2015 Migrant Dynamics Monitor...This study analyzes the relationship between the age of first migration and the probability of repeat migration focusing on rural to urban migrants in China.It is based on the data of the 2015 Migrant Dynamics Monitoring Survey(MDMS).The data shows that 52.64% of migrants had experienced repeat migration before 2015,the amount of which is huge.The empirical results indicate an inverted U-shaped connection between age of first migration and the probability of repeat migration.The probability of making repeat migration from rural to urban areas reaches its peak if an individual experienced his/her first migration at around 16 years old.The probability for repeat migration continues to increase before the age of 16 and keeps dropping afterward.Additionally,this study explores the reason for this inverse U-shaped relationship,and it finds that reasons for first migration have great impacts.Specifically,the probability of repeat migration goes up with age if an individual first migrates before age 16 and is accompanied by parents.This probability decreases with age,if an individual first migrates after or at age 16,because of work.展开更多
When we read Mr. Jun Zhu′s paper: a model of the age patterns of births by parity in natural fertility populations published in Mathematical Population Studies, Vol.4(3), pp.153～173, 1994, it really surprised us by ...When we read Mr. Jun Zhu′s paper: a model of the age patterns of births by parity in natural fertility populations published in Mathematical Population Studies, Vol.4(3), pp.153～173, 1994, it really surprised us by his creative ideas and perfect results. We studied the paper deliberately because it is a remarkable work, and could be a significant contribution to the modeling of fertility analysis. As some contents not perceivable to us, we would expect to discuss with Mr. Jun Zhu to make a clear comprehension of the models in the paper. Our aim is to lead the models and the theory more reliable and practical.展开更多
Dear Editor,The brain experiences ongoing changes across different ages to support brain development and functional reorganization.During the span of adulthood,although the brain has matured from a neurobiological per...Dear Editor,The brain experiences ongoing changes across different ages to support brain development and functional reorganization.During the span of adulthood,although the brain has matured from a neurobiological perspective,it is still continuously shaped by external factors such as habits,the family setting,socioeconomic status,and the work environment [1].In contrast to chronological age (CA),brain(or biological) age (BA) is conceptualized as an important index for characterizing the aging process and neuropsychological state,as well as individual cognitiveperformance.Growing evidence indicates that BA can be assessed by neuroimaging techniques,including MRI [2].展开更多
文摘This study analyzes the relationship between the age of first migration and the probability of repeat migration focusing on rural to urban migrants in China.It is based on the data of the 2015 Migrant Dynamics Monitoring Survey(MDMS).The data shows that 52.64% of migrants had experienced repeat migration before 2015,the amount of which is huge.The empirical results indicate an inverted U-shaped connection between age of first migration and the probability of repeat migration.The probability of making repeat migration from rural to urban areas reaches its peak if an individual experienced his/her first migration at around 16 years old.The probability for repeat migration continues to increase before the age of 16 and keeps dropping afterward.Additionally,this study explores the reason for this inverse U-shaped relationship,and it finds that reasons for first migration have great impacts.Specifically,the probability of repeat migration goes up with age if an individual first migrates before age 16 and is accompanied by parents.This probability decreases with age,if an individual first migrates after or at age 16,because of work.
文摘When we read Mr. Jun Zhu′s paper: a model of the age patterns of births by parity in natural fertility populations published in Mathematical Population Studies, Vol.4(3), pp.153～173, 1994, it really surprised us by his creative ideas and perfect results. We studied the paper deliberately because it is a remarkable work, and could be a significant contribution to the modeling of fertility analysis. As some contents not perceivable to us, we would expect to discuss with Mr. Jun Zhu to make a clear comprehension of the models in the paper. Our aim is to lead the models and the theory more reliable and practical.
基金supported by the National Natural Science Foundation of China(61971420)the Beijing Brain Initiative of the Beijing Municipal Science and Technology Commission(Z181100001518003)+1 种基金Special Projects of Brain Science of the Beijing Municipal Science and Technology Commission(Z161100000216139 and Z171100000117002)the International Cooperation and Exchange of the National Natural Science Foundation of China(31620103905)。
文摘Dear Editor,The brain experiences ongoing changes across different ages to support brain development and functional reorganization.During the span of adulthood,although the brain has matured from a neurobiological perspective,it is still continuously shaped by external factors such as habits,the family setting,socioeconomic status,and the work environment [1].In contrast to chronological age (CA),brain(or biological) age (BA) is conceptualized as an important index for characterizing the aging process and neuropsychological state,as well as individual cognitiveperformance.Growing evidence indicates that BA can be assessed by neuroimaging techniques,including MRI [2].
