Endolithic cyanobacteria in halite rocks from the hyperarid core of the Atacama Desert

In the driest parts of the Atacama Desert there are no visible life forms on soil or rock surfaces. The soil in this region contains only minute traces of bacteria distributed in patches, and conditions are too dry for cyanobacteria that live under translucent stones. Here we show that halite evaporite rocks from the driest part of the Atacama Desert are colonized by cyanobacteria. This colonization takes place just a few millimeters beneath the rock surface, occupying spaces among salt crystals. Our work reveals that these communities are composed of extremely resistant Chroococcidiopsis morphospecies of cyanobacteria and associated heterotrophic bacteria. This newly discovered endolithic environment is an extremely dry and, at the same time, saline microbial habitat. Photosynthetic microorganisms within dry evaporite rocks could be an important and previously unrecognized target for the search for life within our Solar System.     

感受沙漠边缘遥远的且末导航站

人在旅途，最能真切的感受到新疆之大。去年10月底，为了完成通信导航人员上岗执照的考核任务，我和新疆机场集团公司航务信息部的工程师杨东一道从库尔勒机场奔赴且末导航站。因且末机场停航，我们只能乘车穿越那条足有800公里长的“沙漠之路”。     

A microbial oasis in the hypersaline Atacama subsurface discovered by a life detector chip: implications for the search for life on Mars

The Atacama Desert has long been considered a good Mars analogue for testing instrumentation for planetary exploration, but very few data (if any) have been reported about the geomicrobiology of its salt-rich subsurface. We performed a Mars analogue drilling campaign next to the Salar Grande (Atacama, Chile) in July 2009, and several cores and powder samples from up to 5?m deep were analyzed in situ with LDChip300 (a Life Detector Chip containing 300 antibodies). Here, we show the discovery of a hypersaline subsurface microbial habitat associated with halite-, nitrate-, and perchlorate-containing salts at 2?m deep. LDChip300 detected bacteria, archaea, and other biological material (DNA, exopolysaccharides, some peptides) from the analysis of less than 0.5?g of ground core sample. The results were supported by oligonucleotide microarray hybridization in the field and finally confirmed by molecular phylogenetic analysis and direct visualization of microbial cells bound to halite crystals in the laboratory. Geochemical analyses revealed a habitat with abundant hygroscopic salts like halite (up to 260?g kg(-1)) and perchlorate (41.13?μg g(-1) maximum), which allow deliquescence events at low relative humidity. Thin liquid water films would permit microbes to proliferate by using detected organic acids like acetate (19.14?μg g(-1)) or formate (76.06?μg g(-1)) as electron donors, and sulfate (15875?μg g(-1)), nitrate (13490?μg g(-1)), or perchlorate as acceptors. Our results correlate with the discovery of similar hygroscopic salts and possible deliquescence processes on Mars, and open new search strategies for subsurface martian biota. The performance demonstrated by our LDChip300 validates this technology for planetary exploration, particularly for the search for life on Mars.     

A global geographical survey of received signal strength in the VHF band

Sumbandila (SO-67) is an 81 kg LEO satellite launched on 17 September 2009. Its primary payload is a multi-spectral imager with a ground sampling distance of 6.25 m at an orbit altitude of 500 km. Its two command transceivers operate in the commercial and amateur radio VHF and UHF bands and one of them provides a VHF to UHF repeater service to radio amateurs. This paper presents initial results of a global three week monitoring period of two VHF frequency ranges. The data is obtained by executing on-board flight control procedures to select the frequencies to measure. The existing on-board telemetry gathering system is employed to record the data, most notably the received signal strength for the selected frequency. The data is downloaded using an adaptation of the imagery data download path. We determine regions of high signal levels by distributing individual measurements over cells in the satellite footprint before averaging over the cells. The data is then plotted on a geographical signal strength heatmap. We compare our results with that of a similar study of the late 1990s and point out changes since then. The data provides useful information for selecting future ground station locations for minimum interference. It further gives an indication of frequencies to use for command and telemetry communication at existing ground stations. We propose that including a receiver capable of measuring frequency interference across a desired frequency range is very useful to future missions for selecting communication frequencies from this range for ground station locations.     

A culture-independent survey of the bacterial community in a radon hot spring

Paralana is an active, radon-containing hot spring situated in a region of South Australia's Flinders Ranges with a long history of hydrothermal activity. Our aim was to determine the bacterial composition of Paralana using a culture-independent, 16S rRNA-based technique. The presence of a diverse bacterial community was strongly suggested by the large number (approximately 180) of different ribotypes obtained upon analysis of nine hot spring samples. DNA sequencing of Paralana 16S rRNA genes corroborated this observation, identifying representatives of seven confirmed and two candidate divisions of the domain Bacteria. These included Cyanobacteria, Proteobacteria (both beta and delta subdivisions), the Cytophaga-Flexibacter-Bacteroides group, Low G + C Gram-positives, Nitrospira, green non-sulfur bacteria, green sulfur bacteria, OP8, and OP12. No known ionizing radiation-resistant Bacteria were identified. Only one Paralana 16S rRNA sequence type (recombinant B5D) was homologous to a sequence previously identified from a radioactive environment.     

Response to hypogravity of normal in vitro cultured follicular cells from thyroid

Aim of this investigation is the study of molecular modifications occurring in differentiated mammalian cells exposed to gravitational changes. The test system chosen is a well characterized clone of differentiated, normal thyroid follicular cells (FRTL5) in long-term culture. As a follow-up to our recent experiment performed during the MASER-7 sounding rocket mission, flown for European Space Agency by Swedish Space Corporation in May 1996, we evaluated FRTL5 cells responses to Thyroid Stimulating Hormone dependent cAMP production under acute hypogravity conditions obtained in a fast rotating clinostat. Following this approach, we evaluated the FRTL5 cells response to TSH under microgravity conditions in order to optimize experimental tools and strategies in preparation to, and in between real flight missions.     

Seismo-Ionospheric Variations during Strong Earthquakes Based on the Example of the 2010 Earthquake in Chile

Seismo-ionospheric variations during the strong earthquake on February 27, 2010 in Chile have been considered. An analysis of the ionospheric state has been performed using measurements based on a GPS satellite navigation system. The results of processing have shown that the decrease in the electron concentration on February 24, 2010 relative to the preceding day was from 24 to 35%. It has also been noted that, 3 days prior to the seismic event, a substantial drop in the rate of change of in the total electron content was observed near the epicenter zone for 1.5 h. It has been shown that, directly before the earthquake, instantaneous variations in the rate of change in the electron content by an order of value that exceeds normal background behavior was observed.     

开展大学生课外科技活动初探

大学生课外科技活动是科学素质教育的重要环节。课外科技活动的顺利开展对于全面培养综合素质较高的应用性人才具有十分重要的意义．论文就开展大学生课外科技活动的主要内容，重要意义进行了论述和分析，并提出了促进大学生课外科技活动开展的措施。     

固体火箭发动机中铝粉燃烧研究概述

介绍了固体火箭发动机中单个铝颗粒燃烧模型的发展与铝颗粒的燃烧特性;阐述了铝粉分布燃烧现象、分布燃烧放热与声场的耦合关系及其对发动机稳定性的增益作用;总结了惰性颗粒的阻尼理论以及在表面旋涡脱落条件下惰性颗粒对压强振荡的放大作用;提出了应从复杂流场中全面考虑铝粉燃烧对发动机的增益与阻尼作用,建立其对发动机工作稳定性影响的综...     

Cross-cultural issues in space operations: A survey study among ground personnel of the European Space Agency

Today's space operations involve co-working of people with different ethnical, professional and organisational backgrounds. The aim of this study was to examine the implications of cultural diversity for efficient collaboration within the European Space Agency (ESA), and between ESA employees and representatives from other agencies. ESA employees from European countries (N=576) answered to the CULT Ground Survey. The results showed that differences in relation to leadership and decision making were the most important issues thought to interfere with efficient co-working within ESA, and between ESA employees and colleagues from other agencies. Employees who collaborated with more than three nationalities within ESA indicated most challenges in co-working due to differences in compliance, behavioural norms and competitiveness. Challenges in co-working differed between agencies, and these differences were consistent with value differences in the national populations. The results may have applied value for training of European employees working in international space program teams.     

Analysis of satellite systems for the periodic survey of the Earth

Satellite systems for the periodic survey of a given range of the Earth’s latitudes have been analyzed. As a rule, the efficiency of the satellite systems is estimated based on the maximum interruption, i.e., the maximum time interval that appears when surveying. However, this performance cannot serve as a full criterion for the quality of the survey, since it does not reflect all survey interruptions with their frequencies. To adequately analyze the operation of the satellite system, it is necessary to use the frequency distribution function of the survey interruptions; its determination is a complex problem and has not yet been solved in the general case. In this paper, we propose a method for calculating the set of all interruptions and frequencies suitable for any multisatellite systems with an arbitrary structure. The method is based on the vector model of the Earth’s survey. To estimate the efficiency of the satellite system operation, a complex criterion has been recommended that takes into account all survey interruptions and their frequencies. Two examples of the application of the developed method have been presented.     

Induction of vascular endothelial phenotype and cellular proliferation from human cord blood stem cells cultured in simulated microgravity

Recent studies have demonstrated that stem cells derived from adult hematopoietic tissues are capable of trans-differentiation into non-hematopoietic cells, and that the culture in microgravity (microg) may modulate the proliferation and differentiation. We investigated the application of microg to human umbilical cord blood stem cells (CBSC) in the induction of vascular endothelial phenotype expression and cellular proliferation. CD34+ mononuclear cells were isolated from waste human umbilical cord blood samples and cultured in simulated microg for 14 days. The cells were seeded in rotary wall vessels (RWV) with or without microcarrier beads (MCB) and vascular endothelial growth factor was added during culture. Controls consisted of culture in 1 G. The cell cultures in RWV were examined by inverted microscopy. Cell counts, endothelial cell and leukocyte markers performed by flow cytometry and FACS scan were assayed at days 1, 4, 7 and at the termination of the experiments. Culture in RWV revealed significantly increased cellular proliferation with three-dimensional (3D) tissue-like aggregates. At day 4, CD34+ cells cultured in RWV bioreactor without MCB developed vascular tubular assemblies and exhibited endothelial phenotypic markers. These data suggest that CD34+ human umbilical cord blood progenitors are capable of trans-differentiation into vascular endothelial cell phenotype and assemble into 3D tissue structures. Culture of CBSC in simulated microg may be potentially beneficial in the fields of stem cell biology and somatic cell therapy.     

一种从月面图像检测陨石坑的方法

随着我国月球探测计划的开展,基于视觉的探测器月球表面软着陆的相关技术研究正在进行,陨石坑是月球表面最常见的物体.基于图像的陨石坑识别技术作为探测器自主障碍检测中的一项关键技术,引起了各航天大国的高度重视.提出了一种基于特征点的陨石坑检测算法.该方法可以分为三个部分:特征点检测、陨石坑区域初选、陨石坑拟合.首先通过特征点检测初步确定陨石坑所在区域,然后通过区域生长的方法分别提取陨石坑亮、暗两区域,最后通过椭圆拟合的方式获得陨石坑所在椭圆.实验研究表明,该算法可以有效地检测出半径小于15个像素大于5个像素,有较强明暗对比的陨石坑.在结束语中,作者提出了未来该算法改进的四个方向.     

一项基于ESP的高职高专英语教学的实证研究

高职高专英语是指在生产、管理、技术和服务等各行业第一线工作的业务人员所需的英语。在理论上被界定为专门用途英语分支下,介于学术英语与职业英语之间的业务用途英语。本文作者主要从专门用途英语的两个核心特点(目标需求分析与学习需求分析)的角度对高职高专英语教学做了一项实证研究。     

A Technique for Estimating the Space Debris Density from the Data of Onboard Recording Systems

A three-dimensional mathematical model and a program complex for modeling the external effect of small-sized space debris particles on a spacecraft are developed. On the basis of the rectangular contributions method a new technique is developed for restoring the density of small-sized space debris from a small number of recorded debris collisions with recording sensors. From the form of the density function the total number of points having reached the spacecraft surface is restored. The comparative results of modeling are presented.     

Egocentric frames of reference used for the retrieval of survey knowledge learned by map and navigation

Two experiments are reported that use a ``point-to-unseen-targets' task to study the role of egocentric reference frames in the retrieval of survey knowledge learned from either studying a map or navigating an environment. In Experiment 1, performance was generally consistent with the hypothesis that map knowledge is retrieved using a frame of reference centered on the eye, characterized by (a) a fixed orientation in a ``frontal representational plane' and (b) equal access to spatial relations both in front of, or above, and behind, or below, a right-left retrieval axis. The results of Experiment 2 were consistent with the hypothesis that environment knowledge is retrieved within a frame of reference centered on the body, characterized by (a) flexible orientation within a ``transverse representational plane' and (b) privileged access to spatial relations located in front of the right-left retrieval axis in representational space. Both types of knowledge function as if they preserve information about the Euclidean angles connecting elements in physical space.     

从语篇衔接评析《宿建德江》及其三个英译本

论文对《宿建德江》原文及其三个英译本中的语篇衔接手段的运用进行了比较和探讨，指出从语篇衔接的视角来评析译文可以更好地把握汉诗英译的语篇重构，从而启迪译者／读者从一个新的视角审视汉诗英译问题。     

利用有限域上的辛几何构作一类Cartesian认证码

利用了有限域上的辛几何构造了一类Cartesian认证码，并且计算了其参数及模仿攻击成功的概率和替换攻击成功的概率．     

利用有限域上的辛几何构作一类Cartesian认证码

利用了有限域上的辛几何构造了一类Cartesian认证码,并且计算了其参数及模仿攻击成功的概率和替换攻击成功的概率.     

从广告翻译实践看中英文化差异

文化差异在翻译实践活动中普遍存在。广告翻译不仅是语言的翻译,还包含着文化上的转换。因此,在翻译广告的时候,译者必须注意这些文化元素的影响,选用适当的翻译策略。同时,从这些广告翻译策略的运用中,读者也可透视到中英两种文化的差异。