This paper presents a new method for automatic sleep stage classification which is based on the EEG permutation entropy. The EEG permutation entropy has notable distinction in each stage of sleep and manifests the trend of regular transforming. So it can be used as features of sleep EEG in each stage. Nearest neighbor is employed as the pattern recognition method to classify the stages of sleep. Experiments are conducted on 750 sleep EEG samples and the mean identification rate can be up to 79.6%.
Classification ; methods ; Electroencephalography ; methods ; Entropy ; Humans ; Pattern Recognition, Automated ; Signal Processing, Computer-Assisted ; Sleep Stages ; physiology

OBJECTIVE:To establish the method for content determination of cantharidin in Lytta caraganae,and to use the result as the extract screening evidence of L. caraganae source material. METHODS:Ultrasonic extraction method was used to extract cantharidin from L. caraganae using acetone as solvent. HPLC method was adopted to determine the content of cantharidin. The determination was performed on C18column with mobile phase consisted of methanol-water(23:77)at flow rate of 1.0 mL/min. The detection wavelength was set 230 nm,the column temperature was set at 35 ℃,and sample size was 10 μL. The content of cantharidin in L. caraganae was determined and compared with the results of content determination by the method stated in Chinese Pharmacopeia(using chloroform as extraction solvent). RESULTS:The liner range of cantharidin were 0.2-1.0 mg/mL (r=0.998 8)with average methodology recovery rates of 101.1%(RSD=1.7%,n=6). The average content of cantharidin in L. caraganae was 0.932%(n=3),while the content of cantharidin was 0.793%(n=3)determined by the method stated in Chinese Pharmacopeia. Both were higher than the requirement of Chinese Pharmacopeia that the content of cantharidin in scource material of cantharidin was higher than 0.35%. CONCLUSIONS:Established method is accurate and reliable for the content determination cantharidin in L. caraganae. The content of cantharidin is up to the standard of Chinese Pharmacopeia,and can be used as source material for exacting cantharidin.