[Objective]To analyze the Yunqi characteristics and periodicity of drought disasters in He'nan Province during 2000 years.[Methods]On the foundation of the drought data of He'nan Province from 221 BC to 1840 AD,a hierarchical classification was conducted,using statistical tools and wavelet analysis to explore the frequency and periodicity of drought in different Yunqi periods.[Results]The most frequent dominant Qi period of drought in He'nan Province was 4th Qi(Taiyin Shitu)(P<0.001),the most of Sitian period was Jueyin Fengmu and Shaoyin Junhuo(P<0.05),the most of Zaiquan period was Shaoyang Xianghuo(P<0.05).At multiple time scales,drought disasters in He'nan Province had 4 quasi-cycles,the 1st to the 4th quasi-cycles were 510,690,300 and 150 years,respectively.[Conclusion]There was a significant difference in the frequency of drought levels in He'nan Province in different periods of dominant Qi,Sitian period and Zaiquan period,which was partly consistent with the Yunqi theory.Besides,the drought disaster in He'nan Province had certain periodic characteristics.

[Objective]To analyze the Yunqi characteristics and periodicity of drought disasters in He'nan Province during 2000 years.[Methods]On the foundation of the drought data of He'nan Province from 221 BC to 1840 AD,a hierarchical classification was conducted,using statistical tools and wavelet analysis to explore the frequency and periodicity of drought in different Yunqi periods.[Results]The most frequent dominant Qi period of drought in He'nan Province was 4th Qi(Taiyin Shitu)(P<0.001),the most of Sitian period was Jueyin Fengmu and Shaoyin Junhuo(P<0.05),the most of Zaiquan period was Shaoyang Xianghuo(P<0.05).At multiple time scales,drought disasters in He'nan Province had 4 quasi-cycles,the 1st to the 4th quasi-cycles were 510,690,300 and 150 years,respectively.[Conclusion]There was a significant difference in the frequency of drought levels in He'nan Province in different periods of dominant Qi,Sitian period and Zaiquan period,which was partly consistent with the Yunqi theory.Besides,the drought disaster in He'nan Province had certain periodic characteristics.

Objective To explore the value of multislice computed tomography (MSCT) in diagnosis of vascular rings associated airway abnormalities in children. Methods CT image data were retrospective analysis in 159 cases of vascular rings, including multiplanar reconstruction (MPR), maximum and minimum density project reconstructions. The relationship between the vascular rings and airway had been observed. Results Of 159 cases of vascular rings as-sociated with airway stenosis in 101 cases, the main airway stenosis in 79 cases, left main bronchial stenosis in 14 cas-es, right main bronchus in 8 cases, tracheal bridge in 14 cases, tracheal bronchial in 11 cases, symmetry bronchial in 2 cases. Conclusions Vascular ring often causes compression of airway narrow and dysplasia. MSCT can clearly display vascular rings and its relationship with airway, providing help for surgical and reasonable treatment.