Objective To clarify the effects of simulated microgravity on the local regulating function of the pulmonary circulation. Method Rat tail-suspension(TS) was used as the animal model to simulate the effects of microgravity.The changes in responses of pulmonary artery to several vasoactive agents were determined by using in vitro vessel rings perfusion technique. Result As for the endothelium-intact vessel rings from TS group compared with those from the control(C) group,the contractile responses of pulmonary artery to potassium chloride (KCl,10～70 mmol/L) did not change obviously after 7 d tail-suspension,which were markedly diminished as to phenylephrine (PE,10-9～10-5mol/L).The vasodilatory responses to acetylcholine (ACh,10-9～10-5mol/L) were markedly enhanced,which did not change obviously as to captopril (Cap,10-5～3×10-3 mol/L).The vasoreactivity of endothelium-removed pulmonary artery rings to all vasoactive agents did not change after 7 d tail-suspension as compared with those from control rats. Conclusion The release of nitric oxide (NO) by rat pulmonary arterial endothelium was enhanced after 7 d tail-suspension.The vasodilatory function of pulmonary artery was enhanced.

Objective To build the linear models for exploring relations between behavior data and functional magnetic resonance image(fMRI) signals of brain during cognitive task and to validate whether it is reasonable.Methods The linear models of behavior data and fMRI signals were built,and the functional regions of brain were detected by tests of corresponding parameters.Experimental data of Stroop tasks were used to study the effects of the models by comparing with the results of SPM.Results The results of Stroop data showed that dorsal lateral prefrontal cortex(Brodmann 9/46),and superior frontal median cortex(Brodmann 8/9) were associated with response time of Stroop tasks,and accorded with SPM results and other reports.Conclusion The models can quantitatively analyze the relations of response time and fMRI signals,providing a new way to explore functional images of cognition.

Objective To design and establish a set of diffusion optical tomography(DOT) system.Methods Near-infrared(NIR) laser was employed as the light source and only one photomultiplier tube(PMT) as the detector.An optical multiplexer was used to alter the detector channels.The 32 channels of the system,which are consisted of 16 launch channels and 16 detector channels,worked under the continuous-wave(CW) model and were used to acquire 256 boundary data.Results Experiments were performed based on the proposed imaging system.The intralipid was used as the tissue-like medium and the India ink as the absorber.Two sets of data on the boundary were sampled,respectively,before and after the absorber was embedded inside the tissue-like medium.The two sets of data were normalized and then used to reconstruct the absorption coefficient distribution.The recovered image reflected the real location and size of the absorber.Conclusion The proposed imaging platform can image the tissue optical parameters effectively.However the resolution of the reconstructed image was not high because the inverse problem was gravely underdetermined and the noise was not considered in the reconstruction algorithm.The recovered result in the next generation system could be improved by making more use of prior information and enhancing the performance of the system.

Objective To find an efficient and practical reconstruction algorithm for the fluorescence molecular tomography basing on total leastsquares rule as well as the normalized conjugate gradient method.Methods The finite element method was used to get the weighting matrix from the forward diffusion model.For the inverse reconstruction problem,the total least-squares rule was employed.The normalized conjugate gradient method was applied to find the fluorochrome information in the objective area.Results The simulation experiments showed that images reconstructed by the total least-squares rule were more accurate than those reconstructed by the least-squares rule under the same circumstances when noise existed.The presented algorithm could also give consistent results when the initial guesses varied in a wide range.Conclusion The algorithm presented in this paper offers a practical and efficient reconstruction for the fluorescence molecular tomography.

Objective To compare the characters of circadian rhythm of the cardiovascular function between full-term and premature infants.Methods Blood pressure(BP),aortic blood velocity(ABV),aortic blood acceleration(ABA) and aortic strok distance(ASD) were continuously measured in full-term and premature infants for 48 h.Each time series was analyzed with 24-hour cosine curve-fitting method.Results The parameters of cardiovascular function in most of the full-term infants,including BP,ABV,ABA and ASD showed robust circadian rhythm,but most of premature infants did not show obvious circadian rhythm.The averages of those parameters were not different in full-term and premature infants,whereas the amplitude were significant different in the two groups.Conclusion It is indicated that the functions of the cardiovascular system was not different in full-term and premature infants,but circadian rhythm of cardiovascular system in premature infants has not perfectly developed.

Objective To compare the Cosine and Dip methods in describing the rhythm of blood pressure(BP).Methods The BP was measured with non-traumatic ambulatory blood pressure monitoring(ABPM) for 24 h and analyzed with Cosine and Dip methods.The characters of the circadian rhythm of BP were studied and two methods were compared.Results The ratios of mesor and amplitude(A/M) of systolic blood pressure(SBP) and diastolic blood pressure(DBP) were(7.78?0.42)% and(7.98?0.39)%,respectively.The majority of acrophases of BP was on daytime,especially between 10∶00 am and 3∶00 pm.The amplitudes of acrophase in different periods analyzed with Cosine method were not significantly different each other,whereas analyzed with Dip method to be significant difference.Conclusion There is difference between Cosine and Dip methods in describing the rhythm of BP,since rhythms of acrophases of some cases were inaccurately described with Dip method.

Objective To study the characteristics of pointing movement time for targets with different position in front of human body,to detect the effects of targets location on pointing movement time.Methods A pointing movement experiment of human arm was designed and carried out.By the statistic analysis of the experimental data,the relationship between pointing movement time and target position was discussed.Results It was shown that the starting point position and target position extremely affected the pointing movement time.Conclusion When a right-handed person touches the different targets,both the direction to target and the starting point position(target-circle location) would affect the pointing movement time extremely.When the position of the starting point changed by horizontal or vertical,the pointing movement time is more changeful by horizontal than that by vertical.To compare the pointing movement time for each target on a target-circle,the pointing movement time for right-upper target is the shortest.When the starting point is located on the right side of human body,all pointing movement time of that target-circle is the shortest.

Objective To study the cultivating technique of wheat under low pressures as to establish the basis of developing hypobaric controlled ecological life support system.Methods Wheat growing experiments under normal and low pressure(101 kPa,50 kPa) were carried out with low pressure plant-cultivating facilities,and the growing indexes of wheat under low pressure,such as photosynthetic rate,transpiration rate,growing status,yield and nutrient contents in seeds were compared with those under normal pressure.Results Wheat grew normally under low pressure as compared with those grown under normal pressure,but low pressure curled leaves of the wheat and caused them to turn yellow at prophase;after 15 d treatment under hypobaric condition,the average rates of photosynthesis and transpiration increased by 9.23%and 11.54% respectively;shoot height of wheat decreased,both tiller number of each plant and the ratio of root in whole plant increased,but harvest time was delayed for about 5 d under low pressure;the biomass and the yield of wheat increased by 5.46% and 4.39% respectively,the contents of protein and total saccharide in seeds also enhanced at reduced pressure,but other nutrient contents in seeds had no significant difference between 101 kPa and 50 kPa.Conclusion Growth of wheat is promoted in certain degree by low atmospheric pressure.

Objective To study a technology for separating water from gas under microgravity in long-term manned space flight.Methods Several kinds of mixture of water and oxygen were separated by a new water/gas separating matrix and the action of gravity on the process was studied.Results The water/gas separator worked well in the range of gas flow below 2 500 mL/min and water flow below 4～6 L/h.A mixture of gas and water was separated into gas containing no water containing less than 1% gas.The phenomenon of a little oxygen existing in the water flow was explained.It was also found that gravity has nothing to do with the separation.Conclusion Hydrophilic porous membrane can be used to separate water from gas,and further works were continue needed to study the process and to resolve a few problems about water/gas separation under microgravity.

Objective To design an automatic segmentation algorithm for lung region abstraction from CT images in computer-aided diagnosis(CAD) of lung diseases. Methods Based on the optimal threshold segmentation, an automatic region-growing method was adopted to eliminate the trachea and bronchi, the boundary tracking algorithm was modified for background elimination and lung boundary abstraction. Then, lung boundary repair was performed to obtain a fine boundary. To reduce the sensitivity of threshold selection, an iterative process was employed to find the optimal threshold. A trachea/bronchus extraction method based on position of trachea/bronchus in previous slice was introduced, which avoided selecting seed-point by handle in region-growing. Based on previous searching direction, 8-neighborhood searching method was improved to increase its efficiency. Results Experiments with four chest CT data sets showed that this algorithm was able to abstract the lung region automatically, quickly and with better precision. Conclusion The proposed algorithm is quite efficient for automated lung segmentation in the computed-aided diagnosis of lung diseases.