模拟飞机降落过程中的眼动和认知研究

目的：对眼睛运动规律和大脑认知进行实验分析，研究被试者的注意力分配特点。方法：通过模拟飞机的降落过程，用眼动测量设备采集眼动数据并对眼动数据进行分析。结果：实验得到的眼动数据表明，被试者的注意力主要集中在飞机平显上的3个目标兴趣区域，被试者主要在目标兴趣区域之间进行视觉活动、分配和转换注意力。结论：被试者主要利用由上到下（top-down）的认知机制驱动眼动，分配注意力。眼动的结果使被试者获取了飞机飞行的情景意识。     

尾部悬吊对大鼠比目鱼肌梭内外肌纤维乙酰胆碱酯酶活性的影响

目的：研究尾部悬吊对大鼠比目鱼肌肌型和梭内外肌纤维胆碱酯酶活性的影响，探讨失重或模拟失重状态下肌肉萎缩和肌型转换的机制。方法：选用雌性大鼠，以尾部悬吊法模拟失重。实验分为尾部悬吊7d、14d、21d组及相应的同步饲养对照组。以琥珀酸脱氢酶（SDH）确定肌型，检测不同类型梭内外肌纤维乙酰胆碱酯酶（AChE）活性。结果：悬吊使肌肉萎缩、梭外肌纤维构成比发生改变，Ⅰ型纤维减少而Ⅱ型纤维增多。Ⅰ、Ⅱ型梭外肌纤维和梭内肌纤维乙酰胆碱酯酶活性均减弱。结论：模拟失重可导致神经-肌接头胆碱酯酶活性减弱。这种变化可能与运动神经元活动下降有关。     

模拟失重状态人脑波频率涨落分析

目的探讨短期模拟失重对人脑 7～ 1 2Hz频段脑波频率涨落特征的影响 ,为航天员脑功能选拔及训练监测提供功能性评价方法。方法 - 6°头低位卧床 (HDBR)模拟失重状态 ,记录 1 2名 1 8～ 2 2岁男性正常成人卧床前、卧床期间 (第 3、4、6天 )及恢复期 (卧床结束后第 3天 )清醒闭眼安静状态的EEG ,利用脑波频率涨落分析技术分析 7、8、9、1 0、1 1、1 2Hz 6个频率成分的优势涨落特征。结果卧床前 ,枕顶区优势涨落顺序为 1 0、9、1 1Hz;额颞区 1 0、9Hz竞争主优势成分 ,7Hz位居第 3。卧床后 ,各频率成分之间的主次地位和相互关系发生显著的可逆性变化 ,且所涉及的频率成分及脑区逐渐扩展 ,7、8Hz优势显著上升 ,1 0、1 1Hz优势显著下降 ,枕顶及后颞区 9、1 0Hz竞争主优势成分 ,7Hz位居第 3 ;额区及前颞区主次优势频率为 9、7Hz(F4为 7、9Hz) ,1 0Hz位居第 3。结论模拟失重导致脑波 7～ 1 2Hz频段频率涨落竞争结构显著改变 ,脑调节机能变差 ,易导致发作性头痛等临床症状 ,对脑功能造成潜在影响     

Uncertainties in alanine dosimetry in the therapeutic dose range

A method for evaluating the overall uncertainty of alanine EPR transfer dosimetry in the therapeutic dose range is described. The method uses experimental data on EPR signal reproducibility from replicate dosimeters irradiated to low doses (1–5 Gy), estimates of Type B uncertainties, and Monte Carlo simulations of heteroscedastic orthogonal linear regression. A Bruker ECS106 spectrometer and Bruker alanine dosimeters have been used for this evaluation. The results demonstrate that alanine dosimetry can be used for transfer dosimetry in that range with the overall uncertainty 1.5–4% (1σ) depending on the dose, the number of replicate dosimeters, and the duration of the calibration session (the session should not exceed one working day).     

模拟失重条件下骨形态发生蛋白-2诱导的成骨细胞蛋白激酶MEK1活性的变化

目的观察模拟失重条件下由骨形态发生蛋白-2（BMP-2）诱导的大鼠骨肉瘤成骨样细胞（ROS17／2．8）中丝裂原激活的蛋白激酶／细胞外信号调节激酶的激酶1（MAPK／ERK kinase1，MEK1）活性的变化。方法在地面1G和回转器模拟失重条件下培养ROS17／2．8细胞，培养时间分别为24h、48h和72h。培养结束前1h加入BMP-2（500ng／ml），1h后提取细胞蛋白，应用Western Blotting法检测细胞中的总细胞外信号调节激酶1／2（总ERK1／2）和磷酸化细胞外信号调节激酶（p-ERK1／2）的含量。另设一空白对照组，即1G条件下不加BMP-2的培养组。结果7个实验组细胞的总ERK1／2蛋白表达量无明显差异；空白对照组p-ERK1／2的表达量极低，明显低于其他6组（P〈0．01）；各时间点模拟失重组p-ERK1／2表达量均低于1G对照组（P〈0．01）；随着失重时间延长p-ERK1／2表达量呈逐渐降低的趋势（P〈0．01）。结论模拟失重条件下BMP-2诱导的成骨细胞MAPK信号通路中蛋白激酶MEK1的活性下降。     

人生长期间体重与总基础代谢关系的计算机摹拟

本文将人在成长过程中(1～25岁,男、女)的体重与总基础代谢的关系建立一个数学模型,体重与人体细胞总数相关,总基代谢与人体线粒体总数相关,将此模型用计算机摹拟,打印曲线显示,理论分析与实际结果相符。     

航天飞行中潜伏病毒再活化的研究进展

目的综述航天飞行活动中潜伏病毒再活化研究进展.资料来源与选择国内外公开发表的有关论文及研究报告.资料引用国内外发表的文献24篇.资料综合简要概述了航天活动中和地面模拟研究中潜伏病毒的再激活现象并展望其在未来航天研究中的重要性.结论潜伏病毒再活化研究在航天飞行中具重要意义,应在我国载人航天飞行中开展此类研究.     

飞行人员宇宙辐射受照剂量计算机估算系统

目的为了保障机组人员健康和飞行安全,研究开发宇宙辐射剂量计算机估算系统.方法先通过模拟和测量数据,根据给定日期、地理坐标和海拔计算剂量率,然后按照飞行信息计算航程有效剂量.结果用该系统计算的剂量率和航线剂量的数值结果满足国际放射防护委员会60号出版物的精度要求.结论该计算机宇宙辐射剂量估算系统适用于航空公司辐射防护管理.     

A role for computer simulation in solving the riddles of autoreceptor-mediated regulation of GABA release

Summary The autoreceptor-mediated control of GABA release was simulated on a personal computer using commercially available software (STELLA^TM/ITHINK^TM). The experimental data to be matched were taken from previous publications. A basic model was able to fairly accurately reproduce frequency dependencies of GABA release in the presence and absence of uptake inhibition as well as concentration-response curves for changes in release produced by the agonist, (–)-baclofen, or by relatively low concentrations of the antagonists, phaclofen and CGP 35348. Obvious mismatch was observed at high concentrations of a potent antagonist, at a stimulation frequency of 2 Hz. Whereas the experimental data indicate a 3-fold increase in release as compared to controls, simulation predicts a 7-fold increase. By adaptation of the model, simulation data were obtained indicating that this mismatch was not due to (a) the autoreceptor occurring as two subtypes with different affinities for antagonists, (b) the occurrence of an agonist and antagonist state of the autoreceptor, with the latter prevailing at low synaptic concentrations of endogenous GABA, and (c) overruling of uptake inhibition by markedly elevated synaptic GABA concentrations. On the other hand, a simple restriction of the amount of transmitter able to be released per time unit produced much better matching data. A refined model assuming a restricted replacement capacity for exocytotically emptied synaptic vesicles at their docking sites gave similar results. As a consequence, we shall attempt to address this possibility experimentally.Simulation can never prove a case in the positive sense. It can, however, help to exclude ill-matching solutions of a problem and to prioritize among possible ones, which then must be experimentally addressed. We found simulation with this user-friendly software extraordinarily useful, also and not least because it necessitates and stimulates very intense dealing with a subject.Correspondence to: P. C. Waldmeier at the above address     

Zero and first moment area estimation from microdialysis data

Summary The calculation of classical pharmacokinetic parameters from microdialysis data has been described in a previous paper. In this paper I have derived methods for calculating AUMC and AUC from the time-integral type of data that are generated in microdialysis pharmacokinetics experiments. The method derived to estimate AUC is elementary, but is given a theoretical basis using principles of mathematical real analysis, clearly stating the assumptions.The method derived to estimate AUMC is a numerical approximation method based on the linear trapezoidal method. A simulation study was performed to evaluate the precision of the methods and to compare them with corresponding methods for analysis of blood sample data.The estimates from the presently derived methods have a small bias and a small variance. In the simulation study I investigated the influence of model parameters, number of samples, size of statistical error, and the size of the AUC beyond the last sample. Finally, I have given numerical examples from real data to illustrate the use of the method.