Objective:To explore the changes of dynamic cerebral autoregulation ability in pilots exposed to acute positive acceleration(+ Gz) by transcranial Doppler combined with beat-to-beat blood pressure.Methods:A total of 26 pilots enrolled in the + 8Gz manned centrifuge trial at the Air Force Medical Center, Air Force Medical University from June to October 2022 were prospectively included. Blood pressure and heart rate were monitored in the resting state before the trial and within 5 min after centrifugation. Transcranial Doppler combined with noninvasive continuous beat-to-beat blood pressure monitor were used to detect bilateral middle cerebral artery blood flow velocity and beat-to-beat pulse pressure respectively. The transfer function analysis was applied to derive the parameters of cerebral blood flow autoregulation in each frequency band from 0.02 to 0.50 Hz, and the phase, gain and coherence were calculated. The above parameters were compared between resting state and after acute + 8Gz positive acceleration exposure.Results:Compared with the resting state, in all of the 26 pilots after acute + 8Gz positive acceleration exposure, the systolic and diastolic blood pressure and heart rate increased significantly ( P<0.001), the phase significantly increased and the gain significantly decreased in the ultra-low frequency band (0.02-0.07 Hz) ( P<0.05); whereas there were no statistical differences of gain and phase in the low frequency band (0.07-0.20 Hz) and the high frequency band (0.20-0.50 Hz) (all P>0.05). Conclusions:Transcranial Doppler combined with beat-to-beat pulse pressure can be used for the assessment of changes in immediate dynamic cerebral autoregulation after acute + Gz exposure, and transfer function analysis of ultra-low frequency band parameters is suitable for this type of evaluation.

Objective To understand the current situation of breastfeeding duration in children aged 0-5 years in Yunnan Province,and to explore the influencing factors of breastfeeding duration.Methods Using the data of the 6th National Health Service Survey in Yunnan Province,1582 children aged 0～5 years in Yunnan Province were selected as the research subjects,and the Kaplan-Meier method and Cox regression were used to analyze the influencing factors of breastfeeding duration.Results The mean duration of breastfeeding for children aged 0～5 years in Yunnan Province was 9.29 months,and region,time of complementary food addition,time of suckling and family income were the main factors influencing the duration of breastfeeding.Conclusion The duration of breastfeeding for children aged 0～5 years in Yunnan Province deviates significantly from the recommendations provided by both the World Health Organization(WHO)and China's child breastfeeding guidelines.Given the current situation,the relevant departments must enhance their focus on this issue.