Oxytocin infusion increases charitable donations regardless of monetary resources

This study examined if the prosocial effects of oxytocin (OT) extend from individuals to a generalized other who is in need. Participants played a series of economic games to earn money and were presented with an opportunity to donate a portion of their earnings to charity. OT did not significantly increase the decision to donate, but among the 36% of participants who did donate, people infused with OT were found to donate 48% more to charity than those given a placebo. The amount of money earned in the experiment had no effect on whether or not a donation was made or the size of a donation. This is the first study showing that OT increases generosity in unilateral exchanges directed toward philanthropic social institutions, as opposed to immediate benefits directed at individuals or groups.     

SIR传染病模型的参数反演

本文将Adams微分方程数值求解方法和神经网络技术相结合,提出了一种适合于SIR传染病模型参数反演的新方法,该方法可以根据不同的传染病类型和传染病发展的不同阶段反演得到SIR模型参数,从而为分析疫情的发展、制定和评判控制措施提供依据.最后本文以北京2003年公布的SARS疫情数据,采用上述方法进行参数反演,计算结果表明反演参数得到的SIR模型计算结果与实测数据相吻合.     

污染环境中单种群生存分析

本文研究了污染环境中种群的动力学模型,基于已有结果,考虑了内禀增长率为非线性函数的情形.利用微分方程定性理论中的比较定理,对于种群的持续生存与绝灭给出了判别条件.     

The ecological rationality of helping others: Potential helpers integrate cues of recipients' need and willingness to sacrifice

Why do humans help others? Many theories focus on dimensions like kinship or reciprocity. On their surface, these theories seem unable to explain help directed at fleeting strangers. In response to this puzzle, researchers have proposed that the mind has ecologically rational systems for providing aid. These systems respond to cues that predicted adaptive behavior during human evolution, regardless of whether such cues continue to be predictive in modern environments. In three studies, we test for two cues that might predict whether a potential benefactor will help a potential recipient: the need of the recipient and the extent to which the recipient is willing to sacrifice for the benefactor. Both cues, in ancestral environments, have the potential to predict whether a long-term relationship might be established. Consistent with past research, we find that both cues matter: Needy people and people willing to sacrifice are helped more. However, the cues are not merely additive: In some cases, the cue of need is ignored and only willingness to sacrifice is used. We discuss these results in terms of recent evolutionary theories of emotions.