Observation evidence for the entropy switch model of substorm onset

The cause of substorm onset is not yet understood. Chen CX(2016) proposed an entropy switch model, in which substorm onset results from the development of interchange instability. In this study, we sought observational evidence for this model by using Time History of Events and Macroscale Interactions during Substorms(THEMIS) data. We examined two events, one with and the other without a streamer before substorm onset. In contrast to the stable magnetosphere, where the total magnetic field strength is a decreasing function and entropy is an increasing function of the downtail distance, in both events the total magnetic field strength and entropy were reversed before substorm onset. After onset, the total magnetic field strength, entropy, and other plasma quantities fluctuated. In addition, a statistical study was performed. By confining the events with THEMIS satellites located in the downtail region between ~8 and ~12 Earth radii, and 3 hours before and after midnight, we found the occurrence rate of the total magnetic field strength reversal to be 69% and the occurrence rate of entropy reversal to be 77% of the total 205 events.

How did women’s education and differential family planning policies shape transition to second and third births in historical China? New evidence from micro data

The influence of China’s family planning policies on fertility transition is widely acknowledged in research studies.However,little is known about how improve-ments in women’s education have shaped reproductive decisions of Chinese women across different family planning regimes,particularly at micro level.This study uses retrospective pooled birth history data from five consecutive population and fam-ily planning surveys collected over the period 1982-2006 to systematically examine the interrelationship between family planning policies and women’s education,and their interactive effect on the second and third birth transitions.We hypothesize that family planning policies had a differential influence on educational groups in reduc-ing the transition to second and third births.The results from discrete time com-plementary log-log survival models provide strong evidence of differential repro-ductive behavior of education groups across time in China,and the simultaneous influence of women’s education and family planning policies in lowering risks to higher parities.The rates of progression to second and third births tend to be lower after the introduction of rigid family planning policies,and more importantly,the policy impact persisted even after adjusting for demographic and socioeconomic factors.The increase in women’s education overall had a depressing effect on transi-tion to higher parities,and family planning policies implemented overtime have had differential effects on women from different educational groups.The findings show that both family planning policies and women’s education have been instrumental in shaping fertility behavior in China.