 The noisy fluctuations arise from the determination of the synthesis reaction rate , and are modeled by asymmetric stable L\'evy motions .
<clarity>  The noisy fluctuations arise from the determination of the synthesis reaction rate , and are modeled by asymmetric stable L\'evy motions .
 The noisy fluctuations arise from the synthesis reaction rate , and are modeled by asymmetric stable L\'evy motions .