Cooling flows induced by Compton cooling resulting from luminous quasars in clusters of galaxies     

Nisikawa Atuko  Asao Habe  & Nobuo Isibasi 《Monthly notices of the Royal Astronomical Society》1998,295(3):632-640

We have studied the effects of Compton cooling on cooling flow by performing numerical hydrodynamic calculations of the time evolution of hot gas in clusters of galaxies with luminous quasars. We assumed various temperatures for the hot intracluster gas. We have shown that the Compton cooling resulting from very luminous quasars is effective in inducing cooling flow, before radiative cooling flow is realized. The mass flux resulting from the cooling flow increases with time, as the Compton-cooled region expands. However, the mass flux of the Compton cooling flow is not large, less than 1 M⊙ yr⁻¹ in our model, because the Compton-cooled region is limited to an inner galactic region around a quasar. Even after the quasar active phase has ceased, the cooling flow will continue for at least 10⁹ yr. The accreted mass is enough to explain X-ray absorption lines in high-redshift quasars, if the Compton-cooled gas is compressed by high-pressure intracluster gas.  相似文献   

影响日本佐渡岛农民实施野生动物友好型耕作的因素探究(英文)     

中村慧  柘植隆宏  大久保悟  武内和彦  西川潮 《资源与生态学报(英文版)》2014,5(4):370-380

野生动物友好型耕作(Wildlife-friendly Farming,WFF)实践是一种维持农田生态恢复的良好方式。本研究的目的在于探讨影响日本佐渡岛农民实施WFF的因素和提出影响这种实践传播的政策。对佐渡岛上把大米销售给日本农业合作社(Japan Agricultural Cooperatives,JA)的5010个农户进行了问卷调查,总共收到2231农户反馈问卷(反馈率45%)。通过与未经认证农民的态度和属性对比,我们确定了影响农民实施WFF的关键因素。与未经认证的农民相比,已认证的农民:(1)对生物多样性和WFF的经济效益表现出更高的兴趣;(2)拥有更多的已认证农民朋友;(3)感受到了来自消费者的更多的压力和期望;(4)当实施WFF时,不受恶劣劳动力或农田条件的限制。为了在佐渡岛进一步宣传WFF,我们建议把WFF实践对稻田生物多样性的有效性信息应用到公共教育中,并在非认证农民和已认证农民之间、农民与消费者之间创建交流的机会。  相似文献