The former leads to couplings between all transitions with the same sign and to absorption reduction . the latter results in couplings , of which two terms have positive sign and with another two have negative sign 产生耦合的另一因素是激发态相干的自发转移，它对其中两个探测跃迁产生正号的耦合，对另两个探测跃迁产生负号的耦合。
Salih said there are positive signs the ongoing buildup of u . s . forces in iraq is helping bring stability to certain areas of the country , and noted that tribal factions in one province have taken up the fight against al - qaida terrorists 他说在伊拉克的美国军事力量也有积极的迹象? ?在国家的某些特定地区保持社会稳定，并且指出某一个省的部落分支积极地进行反恐战争。
On 18 january 2002 , the afcd confirmed that samples collected earlier that month from retail markets and the poultry wholesale market showed positive signs for h5n1 virus . six different strains of h5n1 virus were detected , which again indicated multiple incursions of virus 于二零零二年一月十八日，渔护署证实在一月上旬，由零售街市及家禽批发市场收集的样本，对h5n1病毒呈阳性反应；并发现六种不同的h5n1病毒，由多种途径入侵市场。
