Dynamic detection of wake-sleep transition with reaction time-magnitude

BACKGROUND： According to observable behaviors, sleep and wakefulness are two fundamentally different behavioral states. Although electroencephalogram （EEG） is traditionally used to define sleep stage, it is difficult to detect or to quantify microarousals or disruptions during sleep. In addition initial sleep cannot be defined. It is thought that the wake-sleep transition cannot be defined by EEG patterns. OBJECTIVE： To observe the behavioral response magnitude during wake-sleep transition by EEG monitoring and to define the wake-sleep transition. DESIGN, TIME AND SETTING： A behavioral and neural network study was performed at the Key Lab of Human Being Development and Mental Health of Central China Normal University, and Lab of Brain and Cognitive Science of South Central University for Nationalities, China in July 2007. PARTICIPANTS： A total of 30 healthy volunteers, of equal gender and aged （19.7 ± 1.1 ） years, were recruited from the Central China Normal University, China for this study. None of the subjects had undergone EEG recording prior to this study or received any medication for sleep disturbances. METHODS： A novel adaptive approach was applied to detect wake-sleep transition, which avoided stimulus-induced waking. To test the difference between wake state and wake-sleep transition, the amount of self-information and mutual-information were effective parameters to analyze wake-sleep transition. MAIN OUTCOME MEASURES： The following parameters were measured： morphological changes in reaction time-magnitude, as well as correlation between phase changes and sleep, and wake and wake-sleep transition. RESULTS： There were three typical phases in morphological changes of reaction time-magnitude. With regard to the behavioral definition and criterion for sleep, the phase morphological characteristics displayed good correlation with behavioral states, such as sleep, wakefulness, and sleep onset. Entropy as an indicator of brain cognitive processes was introduced to test for differences between the wakefulness and sleep onset phase. Results indicated a cognitive declined transitional period different between sleep and wake. After staggered cognitive changes during the wake-sleep transition, the brain underwent marked alterations and transitioned into sleep quickly with no bi-directional EEG changes. CONCLUSION： Wake-sleep transition exists as an independent stage.

Application of the predictable model ofregional time-magnitude to North and Southwest China region

In this paper, the method which can combine different seismic data with the different precision and completeness, even the palaeo-earthquake data, has been applied to estimate the yearly seismic moment rate in the seismic region. Based on this, the predictable model of regional time-magnitude has been used in North China and Southwest China. The normal correlation between the time interval of the events and the magnitude of the last strong earthquake shows that the model is suitable. The value of the parameter c is less than the average value of 0.33 that is obtained from the events occurred in the plate boundary in the world. It is explained that the correlativity between the recurrence interval of the earthquake and the magnitude of the last strong event is not obvious. It is shown that the continental earthquakes in China are different from that occurred in the plate boundary and the recurrence model for the continental events are different from the one for the plate boundary events. Finally the seismic risk analysis based on this model for North China and Southwest China is given in this paper.

Synthesized Poisson and renewal model and its application in seismic hazard analysis

In this paper, the 'memory' characteristics of large earthquakes is described by renewal process and the 'memoryless' characteristics of small earthquakes by Poisson process. At the same time, the change of earthquake distribution caused by using model with 'memory' characteristics is considered, so that drawback in the current research which assumes that time and magnitude distributions are independent is overcomed. Also in the paper, effect on the seismic hazard reaults caused by magnitude distribution' s change with time is calculated by a practical example. The results obtained in the paper has some application in the present research on the model with 'memory' characteristics.