Forecast of China’s grain production development and its self-support rate analysis

This paper discuses four stern difficulties and challenges faced by the development of grain production in China. According to the basic national conditions of China and the amount of grain resources in the world market, China must meet the grain demands mainly by her own domestic production. Using the input-occupancy-output techniques and system science methods, this paper makes a forecast about China’s grain output, grain import and self-support rate in the year 2030. The research was supported by the National Natural Science Foundation of China.     

The pulsational behaviour of the rapidly oscillating Ap star HD 122970 during two photometric multisite campaigns

We undertook two time-series photometric multisite campaigns for the rapidly oscillating Ap star HD 122970. The first one, conducted in 1998, resulted in 119 h of data and in the detection of three pulsation frequencies. The presence of possible further modes which held the promise of deriving a mode identification motivated a second worldwide campaign in the year 2001. This second campaign resulted in 203 h of measurement, but did not reveal further modes. Rather, one of the previously detected signals disappeared. The two modes common to both data sets have different spherical degree. They also showed slight frequency modulation, and one of them varied in amplitude as well. Possible causes of the latter behaviour include intrinsic instability of the pulsation spectrum or precession of the pulsational axis and orbital motion in a binary system. Frequency analysis of the Hipparcos observations of the star did not allow us to determine the stellar rotation period. The amplitude and phase behaviour of the two modes of HD 122970 in the Strömgren uvby bands is quite similar to that observed for other roAp stars.