It detects magnetic signals that are produced by the electrical activity of brain cells ? and which have about a billionth of the strength of the earth ' s magnetic field 这种方法能探测到脑细胞的电活动发出的磁信号? ?这种信号的强度只相当于地磁场的一万亿分之一。
2.
Israeli scientists have built a dna computer so tiny that a trillion of them could fit in a test tube and perform a billion operations per second with 99 . 8 percent accuracy 近日以色列科学家成功研制出超微dna计算机，这种计算机虽然只有普通试管的万亿分之一大小，运算速率却达到每秒10亿次，且准确率高达99 . 8 。
