Objective The aim of this study was to determine whether psychomotor performance and visual reaction time were affected by acute exposure to mild or moderate hypoxia. Method Eighteen healthy male volunteers performed finger tapping, simple reaction time(SRT) and 4-choice reaction time(CRT) tests at simulated altitude of 300 m (control),2800 m, 3600 m and 4400 m for 1 h in a hypobaric chamber. Result SaO2 decreased from 98%(control) to 90%,82% and 74% respectively at the various altitudes. All the performance parameters showed no significant change after exposure to 2800 m for 1 h relative to ground level(P>0.05). However the mean reaction time of 4-CRT under 3600 m prolonged and performance decreased as compared with baseline value(P<0.05), and the performance decreased further under 4400 m(P<0.01). No significant difference was found in finger tapping and SRT even under exposure to 4400 m for 1 h.Furthermore, no decrease in correct rate were observed at any altitude (P>0.05). Conclusion The results from this study demonstrated that there were no measurable impairment of visual reaction time and psychomotor performance under exposure to an altitude of 2800 m for 1 h. However, adverse effects on psychomotor performance were observed under 3600 m and over.

Objective To explore a space craft precooling temperature at which excessive thermal stress on the crew member could be prevented or reduced in an overheated launch or reentry module. Method Five young male volunteers wearing a space suit participated in 25 tests at sea level.The space suit was either ventilated in a volume air flow rate of 100 L/min (STPD) with ambient air at temperatures (Ta) of 15℃,10℃,and 5℃,respectively,or not ventilated. Rectal (Tr),mean skin (Tsk) and mean body (Tb) temperatures were measured. Result At Ta 15℃,Tr decreased without significance (from 37.0±0.2℃to 36.7±0.3℃) in 120-min tests,whereas Tsk and Tb decreased significantly,and subjects had local cold strain whether the space suit was ventilated or not; while at Ta 10℃,Tr decreased from 37.0±0.3℃ to 36.3±0.3℃(P<0.05),subjects had a whole body cold strain,and both Tsk and Tb dropped continuously and significantly. Conclusion Ambient temperature 15℃,at which the thermal comfort states of crew was not significantly degraded,was acceptable after precooling in a space craft.

Objective To validate near-infrared cerebral topography (NCT) as a practical toolin tracing the regional hemodynamic changes during normal ischemic stroke model of rat. Method Middle cerebral artery occlusion (MCAO) and photosensitizer induced intracranial infarction model of rat were established. The geometric shape and infarction area were measured by NCT, functional magnetic resonance imaging (fMRI), and TTC stained anatomical imaging techniques. Result In photosensitizer induced infarction model, the correlation between anatomical infarct area and NCT image area for infarct focus were r= 0.897 for 24 h group (P<0.05) and r=0.906 for 2 months group (P<0.01),respectively. The correlation between anatomical infarction area and NCT image area for infarct focus were r=0.820 for normothermia group (P<0.05) and r= 0.851 for hypothermia group (P<0.05), respectively. The correlation between fMRI and NCT image area for infarction focus were r= 0.874 for normothermia group (P<0.05) and r= 0.782 for hypothermia group (P<0.05),respectively. Conclusion Measurement with NCT for infarction focus matched well with fMRI and anatomic sample in rats. NCT technique might be a practical tool for short-term prediction of stroke and the rehabilitation after stroke in real time.

Objective To investigate the left prefrontal lobe activation during semantic and non-semantic encoding tasks with functional near-infrared imaging (fNIRI) technique. Method 22 healthy subjects were assigned semantic encoding and non-semantic encoding tasks. During semantic encoding tasks, subjects were asked to make a meaningful sentence including two unrelated Chinese word pairs, while during non-semantic encoding task they were asked to judge whether the two Chinese word pairs had the same morphological structure or not. Light intensity of two wavelengths (760 nm and 850 nm) diffused through skull and left prefrontal lobe were real-time recorded and used to reconstruct the brain activation image during the experiment. Result With the fNIRI, significant activations were observed in the left inferior prefrontal cortex (Brodmann' areas 45 and 47) during the two tasks, but the evoked activations were more significant for semantic than non-semantic task. These observations were consistent with the results reported by others with functional megnetic resonance imaging(fMRI) and positron-emission tomographyPET.Conclusion The results suggest that fNIRI provides an important, non-invasive way to map the prefrontal activation during cognitive tasks.

Objective System of pressure breathing for +Gz (PBG) has been incorporated into service in the high performance fighter aircraft,but there were significant differences among PBG pressure schedules used in different countries.The purpose of this study was to define an optimal pressure schedule in PBG system.Method Five male subjects wearing GZ-2 anti-G suit and medium-sized bladder vest,plus PBG with 1.6,2.4,and 3.2 kPa/G pressure schedules,respectively,were exposed to rapid onset (3.0 G/s) centrifuge +Gz runs.+Gz protection of PBG with each of the three pressure schedules were measured and the subjective ratings were collected.Result The +Gz protection afforded by PBG with 1.60,2.40,and 3.20 kPa/G pressure schedules were 2.00±0.31,2.54±0.32,and 2.44±0.31 G,respectively.Subjective ratings showed that the PBG with 2.40 kPa/G pressure schedule was better than the other two.Conclusion Our data suggest that a PBG pressure schedule of 2.4 kPa/G in PBG system is optimal.It not only assures the anti-G performance of PBG,but also reduces its side effects.

Objective To obtain the frequency weighting contour for seated Chinese young males in z axis.Method 10 male volunteers served as the subjects.They were exposed to standard vibration stimulus (a sinusoidal vibration of 1.0 m/s2 at 8 Hz) and 14 kinds of sinusoidal experimental vibration stimuli at frequencies from 4 Hz to 80 Hz.The magnitude of the experimental vibration stimulus was changed by the subject through a signal condition and switching device made by ourselves to obtain an equal vibration sensation to the standard vibration.The data were fitted to the same form of the frequency weighting Wk of ISO 2631-1 with the least square method and optimization of parameters.Result Compared with ISO 2631-1,the frequencies weightings of Chinese young males at 16～80 Hz are significantly higher than those of ISO 2631-1(P<0.005),but there are no significant difference between two frequency weighting contours at other frequencies. Conclusion Chinese young males are more sensitive to vibration at 16～80 Hz in Z axis.

Objective To study the response characteristics of left and right brain to signals from left(LVF) and right(RVF) visual fields during cognitive activity. Method ERPs at 9 locations to LVF and RVF signals were compared in 23 normal subjects in 3 task conditions:looking forward only (VC); making switch response to target signals(T) only(SR); making switch response to T differentially(DR). Result (1)Significant difference in ERPs was found between that induced by LVF and RVF signals on left brain especially at frontal location(F5), which appeared as slow negative deflection induced by T and NT from RVF in SR and DR;(2) Condition-dependent unsymmetrical features between left and right brain were found: the slow potential at F5 was significantly more negative in T and contralateral spatial relation(i.e., left brain for RVF) but more positive in NT and ipsilateral relation than that at F6.Conclusion Signals with psychological meaning in RVF might cause more psychological load as suggested by the results obtained in this study.

Objective To study the role of total flavonoids of hippophae rhamnoides in improving contactile function of stretched cardiac myocyte.Method Flavonoids were given to stretched myocytes which were proved their contractile function decline and then myocyte contractile mechanics characteristics and calcium transfer were measured.Result Flavonoids increased myocyte contractility,as indicated by myocyte shortening,velocity of shortening,peak+dL/dt and peak-dL/dt during shortening,in a concentration-dependent manner (r>0.9,P<0.001),and with no relation to the intracellular calcium transfer in the myocytes.Conclusion Flavonoids of the traditional Chinese drug hippophae rhamnoids is effective in improving the contractile function of stretched cardiac myocyte in low dosage.

Objective To explore the effects of acute mild and moderate hypoxia on human mood state.Method The mood states of 18 healthy male volunteers were evaluated by self-assessment questionnaires,profile of mood state (POMS) and state anxiety inventory (S-AI) after random exposure to simulated altitude of 300 m (control),2800m,3600 m and 4400 m for 1 h in a hypobaric chamber.Result The data at 300 m level were taken as the baseline control.The negative mood state factor points (tension,fatigue etc.) increased gradually as the altitude level increased while V (vigor-activity) points had a tendency to decrease (P<0.05 or P<0.01).No significant difference was found in the points of (D,A) even under exposure to 4400 m(P>0.05).At the early period of 2800 m exposure the tension points of POMS and S-AI scores were higher than those of control level (P<0.05) then dropped to baseline level when exposure to this altitude for 1 h.Conclusion Exposure to acute mild hypobaric hypoxia at 2800 m for 1 h has adverse effect on mood state of healthy person and the negative effect was further aggravated with the increment of altitude level.

Objective To determine the effect of heat and noise on erythrocyte memb rane ATPase activities in pilots during flying. Method Twenty- four pilots per forming bombing for 3h (45～53℃, 122～97dB in the cabin) served as the su bjects . 21 ground personnel served as control (27℃ in the room). Blood samples were t aken from both groups before flying (6:00 a.m), and immediately (12:00 a.m.) and 8h (8:00 p.m.) after flying. Na+-K+ATPase, and Ca2+-Mg2+ATPase activities in erythrocyte membran e were determined with colorimetry. Result The Na+-K+ATPase activity in eryth rocyte membrane at 6:00 a.m.in pilots was higher than that in control group at the s ame time (P<0.01). The Ca2+-Mg2+ATPase activities in erythrocyte membrane at 12:00 a .m. and 8:00 p.m. in pilots were significantly higher, compared with those in co ntrol group at the same time (P<0.01). Conclusion The ATPase values obtained in our study were all within normal range, and the daytim e variation of both groups are the same. Exposure of human body to heat and noi se for long time may be harmful, the higher ATPase activity is, the more catabol ism of ATP will be. ATP exhaustion will lead to Ca2+ overload in erythrocy te thus stiffen the red cell membrane.