[Livestock and Poultry Faeces Nitrogen Loading Rate and Its Potential Return to Farmland in China].

To clearly analyze livestock and poultry faeces and the nitrogen loading rate of farmland in different provinces of China and their potential return to agricultural land, the changes of the output of various livestock and poultry faeces in China and the proportion of faeces from all types of livestock and poultry since 1978 were estimated in this paper based on statistical data and literature reviews using the pig manure equivalent (based on nitrogen) and the spatial distribution and pollution risk of livestock and the poultry faeces and nitrogen loading rates. Furthermore, the nitrogen return potential from animal faeces to farmland was analyzed and evaluated for different provinces of China in 2016. The results show that the pig manure equivalent (N) and total N from livestock and poultry faeces in China increases from 1978 to 2005 and is stable from 2005 to 2016.

[Estimation on the size of men who have sex with men among college students in Beijing through the Network Scale-Up Method (NSUM)].

Objective: Network Scale-Up Method (NSUM) was used to estimate the Personal Network Size (C) of college students in Beijing and the size of men who have sex with men (MSM).

Methods: A survey was conducted on Beijing college students to estimate the personal network size (C) through NSUM and then using the back-estimating and attitude adjustment to correct C value and the size of the target population.

Results: The mean of C among Beijing college students was 97 and the differences of C between different majors and different grades were both statistically significant.