Objective To compare the National Aeronautics and Space Administration-task load index (NASA-TLX) scores and the heart rate variability (HRV) of the female pilot cadets under different task conditions and to preliminarily investigate the characteristics of flight mental workload in females . Methods Two factors repeated measurement design was applied in this study .Twenty female pilot cadets of a flight college were chosen as subjects .Their ECG data was collected under the baseline status that they were in theoretical education and the states of preflight , taking off , approaching and landing in simulated and real flying tasks by KF1 physiological parameter recorder . The NASA-TLX scores were used to evaluate the subjective mental workload of the female cadets under baseline status and in all flying stages .The collected data are analyzed by repeated measurement ANOVA and the trends of changes in different flight stages were analyzed by Spearman's non-parameter correlation test . Results Eighteen subjects'NASA-TLX scores and 10 subjects'HR and HRV data were valid .① In analysis of the main effects of task type factors ,18 female pilot cadets'NASA-TLX scores showed significant variance between different tasks (F＝ 8 .294 , P＜0 .01) .The grand average scores both in simulated flight task (49 .47 ± 22 .69) and in real flight task (49 .68 ± 16.85)weresignificantlyhigherthanthatofbaselinestatus [(30.85±13.97);t＝3.506,3.547,P＜0 .05] .The heart rates of 10 female pilot cadets showed statistical significance between different tasks (F＝14 .615 , P＜0 .01) .The average heart rate in simulated flight task [(84 .70 ± 6 .89)beats/min] and in real flight task [(87 .73 ± 8 .79)beats/min] was also significantly higher than that of baseline status [(73 .70 ± 6 .15)beats/min ;t＝4 .029 ,5 .137 ,P＜0 .05] .②At the stage of landing ,NASA-TLX scores of 18 female flight cadets in real flight task (61 .70 ± 13 .15) and in simulated task (60 .54 ± 21.05)weresignificantlyhigherthanthatofbaselinestatus [(30.85±13.97);t＝3.506,3.547,P＜0 .05] .The HRV indexes of 10 female cadets ,including normalized unit low frequency (LFnu) , normalized unit high frequency (HFnu) ,ratio of low and high frequency bands (LF/HF) ,varied significantly in different types of task at the landing stage (F＝9 .015～12 .275 , P＜0 .01) .The LFnu in simulated flight [(90 .88 ± 4 .44)% ] and real flight tasks [(77 .22 ± 12 .04)% ] was higher than that of baseline status [(63 .75 ± 16 .87)% ;] (t＝4 .957 ,2 .462 ,P＜0 .05) ,and the HFnu of the two flight tasks [(9 .11 ± 4 .52)% ,(22 .78 ± 12 .04)% ] was lower than that of baseline status [(36 .25 ± 16 .87)% ;t＝4 .955 ,2 .460 ,P＜0 .05] .The LF/HF in this flight stage showed significant difference between simulated task (13 .51 ± 9 .51) and baseline status [(2 .40 ± 1 .66) ; t＝ 4 .088 , P＜ 0 .05] .③Both in the simulated and real flight tasks ,the NASA-TLX scores of 18 female flight cadets showed rising trend with the flight stage progress (ρ＝0 .328 ,0 .537 ,P＜0 .01) .The rising trends were also found on the LFnu and LF/HF of 10 female flight cadets (ρ＝ 0 .450～0 .631 , P＜ 0 .01) while the descending trends with flight stage progress were found on HFnu in both tasks (ρ＝ - 0 .631 ,-0 .450 ,P＜0 .01) . Conclusions The mental workload of female pilot cadets significantly increases in flight tasks as comparing to the baseline status and is significantly higher in landing stage than before flight .The simulated flight task can provide female pilot cadets basically the same mental workload as the real flight task .It is meaningful to pilot's training and related researches .

Objective To compare the National Aeronautics and Space Administration-task load index (NASA-TLX) scores and the heart rate variability (HRV) of the female pilot cadets under different task conditions and to preliminarily investigate the characteristics of flight mental workload in females . Methods Two factors repeated measurement design was applied in this study .Twenty female pilot cadets of a flight college were chosen as subjects .Their ECG data was collected under the baseline status that they were in theoretical education and the states of preflight , taking off , approaching and landing in simulated and real flying tasks by KF1 physiological parameter recorder . The NASA-TLX scores were used to evaluate the subjective mental workload of the female cadets under baseline status and in all flying stages .The collected data are analyzed by repeated measurement ANOVA and the trends of changes in different flight stages were analyzed by Spearman's non-parameter correlation test . Results Eighteen subjects'NASA-TLX scores and 10 subjects'HR and HRV data were valid .① In analysis of the main effects of task type factors ,18 female pilot cadets'NASA-TLX scores showed significant variance between different tasks (F＝ 8 .294 , P＜0 .01) .The grand average scores both in simulated flight task (49 .47 ± 22 .69) and in real flight task (49 .68 ± 16.85)weresignificantlyhigherthanthatofbaselinestatus [(30.85±13.97);t＝3.506,3.547,P＜0 .05] .The heart rates of 10 female pilot cadets showed statistical significance between different tasks (F＝14 .615 , P＜0 .01) .The average heart rate in simulated flight task [(84 .70 ± 6 .89)beats/min] and in real flight task [(87 .73 ± 8 .79)beats/min] was also significantly higher than that of baseline status [(73 .70 ± 6 .15)beats/min ;t＝4 .029 ,5 .137 ,P＜0 .05] .②At the stage of landing ,NASA-TLX scores of 18 female flight cadets in real flight task (61 .70 ± 13 .15) and in simulated task (60 .54 ± 21.05)weresignificantlyhigherthanthatofbaselinestatus [(30.85±13.97);t＝3.506,3.547,P＜0 .05] .The HRV indexes of 10 female cadets ,including normalized unit low frequency (LFnu) , normalized unit high frequency (HFnu) ,ratio of low and high frequency bands (LF/HF) ,varied significantly in different types of task at the landing stage (F＝9 .015～12 .275 , P＜0 .01) .The LFnu in simulated flight [(90 .88 ± 4 .44)% ] and real flight tasks [(77 .22 ± 12 .04)% ] was higher than that of baseline status [(63 .75 ± 16 .87)% ;] (t＝4 .957 ,2 .462 ,P＜0 .05) ,and the HFnu of the two flight tasks [(9 .11 ± 4 .52)% ,(22 .78 ± 12 .04)% ] was lower than that of baseline status [(36 .25 ± 16 .87)% ;t＝4 .955 ,2 .460 ,P＜0 .05] .The LF/HF in this flight stage showed significant difference between simulated task (13 .51 ± 9 .51) and baseline status [(2 .40 ± 1 .66) ; t＝ 4 .088 , P＜ 0 .05] .③Both in the simulated and real flight tasks ,the NASA-TLX scores of 18 female flight cadets showed rising trend with the flight stage progress (ρ＝0 .328 ,0 .537 ,P＜0 .01) .The rising trends were also found on the LFnu and LF/HF of 10 female flight cadets (ρ＝ 0 .450～0 .631 , P＜ 0 .01) while the descending trends with flight stage progress were found on HFnu in both tasks (ρ＝ - 0 .631 ,-0 .450 ,P＜0 .01) . Conclusions The mental workload of female pilot cadets significantly increases in flight tasks as comparing to the baseline status and is significantly higher in landing stage than before flight .The simulated flight task can provide female pilot cadets basically the same mental workload as the real flight task .It is meaningful to pilot's training and related researches .

Objective:To investigate the changes of gene or protein expression and activity of matrix metalloprotein9 (MMP9) and tissue inhibitor ofmetalloproteinasel (TIMP1) in the carotid artery (CA) of 4 wk hindlimb unweighted rat.Methods:A 4 weeks(wk) hindlimb unweighted (HU) rat model was used to simulate the effect of weightlessness on the cardiovascular system.Transmission electron microscopy was used to detect the content of ECM.Reverse transcriptase polymerase chain reaction(RT-PCR) was conducted to measure the mRNA content MMP and TIMP1.Immunohistochemistry and Western blot technique were used to measure the protein abundance.Gelatin zymography was carried out to detect the activity of MMP9.Results:Compared to the control group (CON),the area of ECM was enhanced (P＜0.05) and the content of collage fiber was increased (P＜0.05) in the CA of HU rats;moreover,HU did not affect the mRNA expression of MMP9,but significantly reduced the protein content (P＜0.05) or enzymatic activity (P＜0.05).Accordingly,the mRNA or protein expression of TIMP1 in the CA was significantly increased by HU (P＜0.05).Conclusion:Simulated weightlessness caused imbalance between MMP and TIMP1 expression,which might contribute to the ECM aggregation and stiffness of CA.

Objective To investigate the sensitivity of common carotid arteries of the rats to ceramide (Cer) regulation after simulated weightlessness.Methods Fourty-eight male Sprague-Dawley rats that matched for weight were randomly assigned to suspended group (n=24) and control group (n =24).Tail suspension of rats was carried out for 4 wk to simulate the effect of weightlessness.Isometric force recording system was used to detect the vasoconstriction and vasodilation response of common carotid arteries ring.Dihydroethidium fluorescent probe was used to evaluate the level of superoxide anion (O2-·) in arteries.Results Vasoconstriction response and vasodilation response showed insignificant difference between suspended group and control group.Incubation with C6-ceramide (C6-Cer) or Cer antibody (anti-Cer) did not change the vasoconstriction response and O2-· level of CA in control group but increased Cer level,vasoconstriction response to KCl and O2-· level of common carotid arteries in control group,and did not change the vasodilation response of common carotid arteries both in control and suspended group.In suspended group,C6-Cer incubation increased vasoconstriction response of common carotid arteries both to potassium chloride and phenylephrine,as well as the O2-· level (t=6.077-12.630,P＜0.05) but less to acetylcholine and nitroprusside sodium.The anti-Cer incubation decreased response vasoconstriction of common carotid arteries in suspended both to potassium chloride and phenylephrine,as well as the O2-· level (t=11.582 32.130,P＜0.05) but the vasodilation response.The incubation of superoxide dismutase or hydrogen peroxide depressed the changes of vasoconstriction response caused by C6-Cer or anti-Cer.Conclusions Cer regulation increases the sensitivity of common carotid arterial constriction in the simulated weightless rats and the mechanism is concerned with reactive oxygen level.

Objective To investigate the sensitivity of common carotid arteries of the rats to ceramide (Cer) regulation after simulated weightlessness.Methods Fourty-eight male Sprague-Dawley rats that matched for weight were randomly assigned to suspended group (n=24) and control group (n =24).Tail suspension of rats was carried out for 4 wk to simulate the effect of weightlessness.Isometric force recording system was used to detect the vasoconstriction and vasodilation response of common carotid arteries ring.Dihydroethidium fluorescent probe was used to evaluate the level of superoxide anion (O2-·) in arteries.Results Vasoconstriction response and vasodilation response showed insignificant difference between suspended group and control group.Incubation with C6-ceramide (C6-Cer) or Cer antibody (anti-Cer) did not change the vasoconstriction response and O2-· level of CA in control group but increased Cer level,vasoconstriction response to KCl and O2-· level of common carotid arteries in control group,and did not change the vasodilation response of common carotid arteries both in control and suspended group.In suspended group,C6-Cer incubation increased vasoconstriction response of common carotid arteries both to potassium chloride and phenylephrine,as well as the O2-· level (t=6.077-12.630,P＜0.05) but less to acetylcholine and nitroprusside sodium.The anti-Cer incubation decreased response vasoconstriction of common carotid arteries in suspended both to potassium chloride and phenylephrine,as well as the O2-· level (t=11.582 32.130,P＜0.05) but the vasodilation response.The incubation of superoxide dismutase or hydrogen peroxide depressed the changes of vasoconstriction response caused by C6-Cer or anti-Cer.Conclusions Cer regulation increases the sensitivity of common carotid arterial constriction in the simulated weightless rats and the mechanism is concerned with reactive oxygen level.