模拟微重力对人骨髓间充质干细胞向成骨细胞分化中细胞信号通路影响的分析

通过模拟来研究微重力对hMSC向成骨细胞分化的影响,并利用相关信号通路的激活剂或抑制剂来调节这一分化过程.研究结果表明,在成骨细胞分化诱导条件下,微重力降低了hMSC向成骨细胞定向分化的能力,并且成骨细胞标记性基因的表达明显降低, Runt相关转录因子2(Ruax2)的表达受到抑制.相反,过氧化物酶体增殖激活受体γ(PPARγ2)的表达则增加.同时,微重力也降低了ERK的磷酸化水平,而增加了p38MAPK的磷酸化水平.使用p38MAPK的抑制剂SB203580能够抑制p38MAPK的磷酸化,但不能降低PPARγ2的表达水平.骨形态发生蛋白(BMP)能增加Runx2的表达水平.成纤维细胞生长因子2(FGF2)增加了ERK的磷酸化水平,但也不能显著增加成骨细胞标记性基因的表达水平.采用BMP,FGF2和SB203580三种因子组合来调控微重力下的成骨细胞分化能力,结果表明三者的协同作用能显著逆转微重力对成骨细胞定向分化的生物学效应.研究结果还说明,模拟微重力应该是通过不同的细胞信号通路来抑制成骨细胞分化和提升脂肪细胞分化的.      

生物组织中光场分布的有限元分析

基于对脑组织多层结构特殊性的认识,将有限元方法应用到脑组织的光场分布模拟研究中,即通过区域划分和分片插值确定基函数,并根据变分原理推导了辐射传输方程在边界条件下的泛函,进而得到每个单元的特征式和整个场的联立方程式,可求解联立方程式得到光场分布的模拟结果.最后,进一步讨论了有限元方法的合理性选择问题,给出有限元方法的适用条件是吸收系数远小于散射系数的生物组织.将此方法和蒙特卡罗方法模拟的光场分布进行比较,结果表明,有限元方法对脑组织内的光场分布模拟相当精确,同时模拟所用的时间大大缩短.     

空管人因失效概率的THERP-CREAM预测方法

管制员的人为差错是导致航空器空中相撞的主要原因之一,对空管人因失效概率进行有效预测是一个难题。为此,提出一种基于人误率预测技术（THERP）与认知可靠性和失误率分析模型（CREAM）的组合空管人因失效概率预测方法,基于THERP技术二叉树模型构建事故发展基本脉络,而后基于CREAM方法对各个人误行为触发概率进行修正,从而得出更为准确的概率预测结果。通过对相似事故进行对比分析,结果表明：本文提出的预测方法可识别关键性的事故影响因子,以便制定有针对性的管控措施,从而为研究预测空管人因失效概率提供了一种有效的分析手段。     

中国书法的文化精神与人格魅力

通过从中国书法的文化精神和人格魅力的解读，阐述了古今书法大家的文化精神与人格魅力；审视了当代书坛现状，提出了重塑中国书法的文化精神与人格魅力的方向，诠释了书学的道德精神修养和学问艺术修养。     

从一起飞机滑梯救生包系带问题浅谈人为因素分析

本文就一起看似简单的B757飞机逃离滑梯救生包系带问题未能正确纠正的事件,结合加拿大运输部的人为差错12个"陷阱"(Dirty Dozen),从人为因素的角度进行了简要的分析,为我们在日常航空安全管理中如何系统地分析、解决问题提供了一个案例。     

Building components for an outpost on the Lunar soil by means of a novel 3D printing technology

3D-printing technologies are receiving an always increasing attention in architecture, due to their potential use for direct construction of buildings and other complex structures, also of considerable dimensions, with virtually any shape. Some of these technologies rely on an agglomeration process of inert materials, e.g. sand, through a special binding liquid and this capability is of interest for the space community for its potential application to space exploration. In fact, it opens the possibility for exploiting in-situ resources for the construction of buildings in harsh spatial environments. The paper presents the results of a study aimed at assessing the concept of 3D printing technology for building habitats on the Moon using lunar soil, also called regolith. A particular patented 3D-printing technology – D-shape – has been applied, which is, among the existing rapid prototyping systems, the closest to achieving full scale construction of buildings and the physical and chemical characteristics of lunar regolith and terrestrial regolith simulants have been assessed with respect to the working principles of such technology. A novel lunar regolith simulant has also been developed, which almost exactly reproduces the characteristics of the JSC-1A simulant produced in the US. Moreover, tests in air and in vacuum have been performed to demonstrate the occurrence of the reticulation reaction with the regolith simulant. The vacuum tests also showed that evaporation or freezing of the binding liquid can be prevented through a proper injection method. The general requirements of a Moon outpost have been specified, and a preliminary design of the habitat has been developed. Based on such design, a section of the outpost wall has been selected and manufactured at full scale using the D-shape printer and regolith simulant. Test pieces have also been manufactured and their mechanical properties have been assessed.     

Human exploration of near earth asteroids: Mission analysis for chemical and electric propulsion

This paper presents a mission analysis comparison of human missions to asteroids using two distinct architectures. The objective is to determine if either architecture can reduce launch mass with respect to the other, while not sacrificing other performance metrics such as mission duration. One architecture relies on chemical propulsion, the traditional workhorse of space exploration. The second combines chemical and electric propulsion into a hybrid architecture that attempts to utilize the strengths of each, namely the short flight times of chemical propulsion and the propellant efficiency of electric propulsion. The architectures are thoroughly detailed, and accessibility of the known asteroid population is determined for both. The most accessible asteroids are discussed in detail. Aspects such as mission abort scenarios and vehicle reusability are also discussed. Ultimately, it is determined that launch mass can be greatly reduced with the hybrid architecture, without a notable increase in mission duration. This demonstrates that significant performance improvements can be introduced to the next step of human space exploration with realistic electric propulsion system capabilities. This leads to immediate cost savings for human exploration and simultaneously opens a path of technology development that leads to technologies enabling access to even further destinations in the future.     

Might astronauts one day be treated like return samples?

The next time humans set foot on the Moon or another planet, will we treat the crew like we would a sample return mission when they come back to Earth? This may seem a surprising or even provocative question, but it is one we need to address. The hurdles and hazards of sending humans to Mars – for example, the technology constraints and physiological and psychological challenges – are many; but let us not forget the need to protect populations and environments from the risk of contamination [United Nations, treaty on principles governing the activities of states in the exploration and use of outer space, including the Moon and other celestial bodies (the “Outer Space Treaty”) referenced 610 UNTS 205 - resolution 2222(XXI) of December 1966].     

An environmentally sensitive dynamic human model for LSS robustness studies with the V-HAB simulation

The development of efficient and safe Life Support Systems is one of the key drivers of the Global Solar System Exploration efforts. For each task performed by Life Support Systems (LSS) a great multitude of sub-system concepts exist and the challenge is to find the optimal combination of sub-systems for a given mission scenario. On a sub-system level the Equivalent Systems Mass (ESM) trade study approach is well suited to effectively compare sub-system options. On a system level in addition to ESM data time dependent sub-system performances within an overall system must be addressed. Criteria such as system stability, controllability and effectiveness must be considered in order to be able to assess the dynamic robustness of systems designed to the averages. In an effort to establish a dynamic simulation environment for this type of LSS optimizations the “Virtual Habitat” tool (V-HAB) is being developed at the Technical University of Munich (TUM). This paper introduces the most important part of the Virtual Habitat simulation, which is the human model.     

Fluid and electrolyte alterations during prolonged hypokinesia

The physiological and biochemical systems that regulate the level of each electrolyte in blood and other endogenous fluids, and the balance between the consumption and loss of fluid and electrolytes and the total fluid and electrolyte content of the body are significantly affected during hypokinesia (HK; diminished movement). Among the known effects of HK, the fluid and electrolyte deficiency has drawn a great interest due to the higher fluid and electrolyte deficiency with higher than lower fluid and electrolyte consumption. The impossibility of the body to use fluid and electrolytes, after the fluid and electrolyte deficiency has been established, has drawn the greatest interest. The fluid shifting to the thoracic region and the daily body rehydration are considered as the most effective methods to counteract fluid and electrolyte changes. To this end, the objective of this review was to report some of the findings in the fluid and electrolyte deficiency and fluid and electrolyte loss with fluid and electrolyte deficiency during prolonged HK.