Degraded EEG response of the human brain in function of gravity levels by the method of chaotic attractor

The measurement of the influence of different gravity levels on the brain allows to explain how humans react to microgravity in space and to predict the adaptation capability of astronauts. Human electroencephalographic (EEG) signals were recorded during low and high gravity phases of three consecutive days of parabolic flights on the Caravelle aircraft in 1991. EEG signals were processed, using the method of correlation dimensions d of chaotic strange attractors. Results show clear differences between the three flights, with a general decrease over time in the attractor dimensions, a measure of the brain response to changing g levels. However, the dimension is not a one-to-one relation with g levels, as additional variations are observed. Two hypotheses are introduced, the "fatigue/stress" and the "g stress" hypotheses corresponding, respectively, to long-term fatigue accumulated over the three flights, and to short-term fatigue in response to change in g levels. The former explains the overall decrease of dimensions, the latter yields additional variations on shorter time scales. As the brain response degrades with time, at least six degraded modes were observed, explained by both short- and long-term fatigue.     

海南地区强磁暴期间强区域扩展F事件研究

利用2004年海南DPS-4数字测高仪观测到的强区域扩展F(SSF)数据,分析研究了5个强磁暴(Dst＜-100 nT)事件期间海南SSF的响应特征.结果发现,在海南地区,5个强磁暴事件中有3个磁暴Dst最小值位于2200-0200 LT之间,在磁暴主相及恢复相初期均出现了SSF现象,这种触发作用可能源于磁层直接渗透电场的作用,而另两个磁暴Dst最小值均发生在白天,一个SSF现象出现在磁暴的恢复相晚间,另一个SSF现象出现在超强磁暴的初相晚间,后者可能由该超强磁暴的急始造成的直接渗透电场所触发;5个强磁暴期间发生的SSF现象或者仅出现在午夜前,或者先出现在午夜前并持续到午夜后;同时,还就这些观测结果与Dabas等人有关磁暴对ESF影响的结论进行对比和讨论.