Background Early marriage and fertility are major social determinants of health and wellbeing. Rapid shifts in the past three decades, including a rise in sexual activity in unmarried adolescents, a large population of young migrant workers, and a high proportion of males relative to females, have the potential to alter patterns of reproductive health in Chinese adolescents and young women. We aimed to establish long-term trends of marriage and fertility for girls and women aged 15-24 years in China. MethodsWe did a longitudinal study in which we extracted aggregated data for marriage and childbearing status for Chinese girls and women aged 15-24 years from the Chinese National Population Census (in 1990, 2000, and 2010) and the Chinese 1% National Population Sample Survey (in 1995, 2005, and 2015). The census included all individuals with Chinese nationality who resided in China when the survey was done. For the 1% sample survey, communities or villages were randomly selected and all residents with Chinese nationality in the selected communities or villages were included. In all censuses and sample surveys, forms that included information on basic demographic characteristics, education, marriage, and fertility were completed and verified by the census enumerators at the household residence, based on responses provided by the householder or another adult in the household. We calculated the ever-married rate and age-specific fertility rate (ASFR) for all included individuals. We built multivariate random-effects generalised least squares regression models on panel data to test whether marriage or fertility rate was associated with education level, sex ratio, and the proportion of the population who are an ethnic minority in a province. FindingsThe ever-married rate for those aged 15-19 years decreased from 4•7% in 1990 to 1•2% (95% CI 1•2-1•3) in 2000, but rebounded to 2•4% (2•4-2•5) in 2015. The ASFR for this age group decreased from 22•0 births per 1000 individuals in 1990 to 6•0 (5•9-6•0) births per 1000 in 2000, and rebounded to 9•2 (8•9-9•4) births per 1000 in 2015. The rebound was found in most provinces. In women aged 20-24 years, the ever-married rate generally declined from 58•6% in 1990 to 25•5% (95% CI 25•4-25•6) in 2015, and the ASFR decreased from 198•8 births per 1000 in 1990 to 55•0 (54•5-55•5) births per 1000 in 2015. In 2015, the ever-married rate and ASFR for girls and women in rural areas aged 15-19 years were three-times higher than those of their urban counterparts (3•8% [95% CI 3•7-3•9] vs 1•1% [1•1-1•1] for the ever-married rate and 15•4 [14•9-15•9] vs 4•1 [3•9-4•3] births per 1000 for the ASFR). There were large disparities in ever-married rate across individuals of different education levels, with increases in the ever-married rate of 15-19-year-olds not attending senior high school between 2000 and 2010. Those aged 15-19 years were more likely to be married or give birth in the western provinces. Education held a protective association against adolescent childbearing, whereas a high ratio...
Red tides are caused by the combination effects of many marine elements. The complexity of the marine ecosystem makes it hard to find the relationship between marine elements and red tides. The algorithm of fuzzyc-means (FCM) can get clear classification of things and expresses the fuzzy state among different things. Therefore, a prediction algorithm of red tide based on improved FCM is proposed. In order to overcome the defect of FCM which is overdependent on the initial cluster centers and the objective function, this paper gains the initial cluster centers through the principle of regional minimum data density and the minimum mean distance. The feature weighted cluster center is added to the objective function. Finally, the improved FCM algorithm is applied in the prediction research of red tide, and the results show that the improved FCM algorithm has good denoising ability and high accuracy in the prediction of red tides.
The "green earth" is the common home for human survival and development. Climate change is a serious challenge to the earth's ecosystem since global industrialization and energy is the fundamental problem of human society. Under the pressure of energy crisis and environmental pollution, it has become an inevitable choice to find new energy vehicles to replace fuel cars, however, the new energy vehicles, mainly pure electric vehicles and hybrid vehicles, are not completely harmless to the environment. The reason is that China's thermal power generation method is also very polluting, and the power industry has become one of the largest polluting industries in China. Based on the meaning of carbon neutrality, this paper explores the impact of new energy vehicles in China on the market to achieve carbon "zero emissions", and analyses the contribution of new energy vehicles to the reduction of oil consumption and carbon emissions generated during battery power generation by accounting for the carbon emissions of new energy vehicles, providing a practical and effective solution to seek green development of the new energy vehicle industry from the top level. This paper argues that to achieve the goal of carbon neutrality by 2060, China needs to continuously optimize the supply and demand structure of new energy vehicles and vigorously develop the photovoltaic industry, which will be a huge driving force for achieving a low-carbon economy.
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