The influence of microgravity on invasive growth in Saccharomyces cerevisiae

This study investigates the effects of microgravity on colony growth and the morphological transition from single cells to short invasive filaments in the model eukaryotic organism Saccharomyces cerevisiae. Two-dimensional spreading of the yeast colonies grown on semi-solid agar medium was reduced under microgravity in the Σ1278b laboratory strain but not in the CMBSESA1 industrial strain. This was supported by the Σ1278b proteome map under microgravity conditions, which revealed upregulation of proteins linked to anaerobic conditions. The Σ1278b strain showed a reduced invasive growth in the center of the yeast colony. Bud scar distribution was slightly affected, with a switch toward more random budding. Together, microgravity conditions disturb spatially programmed budding patterns and generate strain-dependent growth differences in yeast colonies on semi-solid medium.     

SOLID3: a multiplex antibody microarray-based optical sensor instrument for in situ life detection in planetary exploration

The search for unequivocal signs of life on other planetary bodies is one of the major challenges for astrobiology. The failure to detect organic molecules on the surface of Mars by measuring volatile compounds after sample heating, together with the new knowledge of martian soil chemistry, has prompted the astrobiological community to develop new methods and technologies. Based on protein microarray technology, we have designed and built a series of instruments called SOLID (for "Signs Of LIfe Detector") for automatic in situ detection and identification of substances or analytes from liquid and solid samples (soil, sediments, or powder). Here, we present the SOLID3 instrument, which is able to perform both sandwich and competitive immunoassays and consists of two separate functional units: a Sample Preparation Unit (SPU) for 10 different extractions by ultrasonication and a Sample Analysis Unit (SAU) for fluorescent immunoassays. The SAU consists of five different flow cells, with an antibody microarray in each one (2000 spots). It is also equipped with an exclusive optical package and a charge-coupled device (CCD) for fluorescent detection. We demonstrated the performance of SOLID3 in the detection of a broad range of molecular-sized compounds, which range from peptides and proteins to whole cells and spores, with sensitivities at 1-2?ppb (ng?mL?1) for biomolecules and 10? to 103 spores per milliliter. We report its application in the detection of acidophilic microorganisms in the Río Tinto Mars analogue and report the absence of substantial negative effects on the immunoassay in the presence of 50?mM perchlorate (20 times higher than that found at the Phoenix landing site). Our SOLID instrument concept is an excellent option with which to detect biomolecules because it avoids the high-temperature treatments that may destroy organic matter in the presence of martian oxidants.     

Following the kinetics: iron-oxidizing microbial mats in cold icelandic volcanic habitats and their rock-associated carbonaceous signature

Icelandic streams with mean annual temperatures of less than 5 °C, which receive the cationic products of basaltic rock weathering, were found to host mats of iron-cycling microorganisms. We investigated two representative sites. Iron-oxidizing Gallionella and iron-reducing Geobacter species were present. The mats host a high bacterial diversity as determined by culture-independent methods. β-Proteobacteria, Actinobacteria, α-Proteobacteria, and Bacteroidetes were abundant microbial taxa. The mat contained a high number of phototroph sequences. The carbon compounds in the mat displayed broad G and D bands with Raman spectroscopy. This signature becomes incorporated into the weathered oxidized surface layer of the basaltic rocks and was observed on rocks that no longer host mats. The presence of iron-oxidizing taxa in the stream microbial mats, and the lack of them in previously studied volcanic rocks in Iceland that have intermittently been exposed to surface water flows, can be explained by the kinetic limitations to the extraction of reduced iron from rocks. This type of ecosystem illustrates key factors that control the distribution of chemolithotrophs in cold volcanic environments. The data show that one promising sample type for which the hypothesis of the existence of past life on Mars can be tested is the surface of volcanic rocks that, previously, were situated within channels carved by flowing water. Our results also show that the carbonaceous signatures of life, if life had occurred, could be found in or on these rocks.     

A two-tiered approach to assessing the habitability of exoplanets

In the next few years, the number of catalogued exoplanets will be counted in the thousands. This will vastly expand the number of potentially habitable worlds and lead to a systematic assessment of their astrobiological potential. Here, we suggest a two-tiered classification scheme of exoplanet habitability. The first tier consists of an Earth Similarity Index (ESI), which allows worlds to be screened with regard to their similarity to Earth, the only known inhabited planet at this time. The ESI is based on data available or potentially available for most exoplanets such as mass, radius, and temperature. For the second tier of the classification scheme we propose a Planetary Habitability Index (PHI) based on the presence of a stable substrate, available energy, appropriate chemistry, and the potential for holding a liquid solvent. The PHI has been designed to minimize the biased search for life as we know it and to take into account life that might exist under more exotic conditions. As such, the PHI requires more detailed knowledge than is available for any exoplanet at this time. However, future missions such as the Terrestrial Planet Finder will collect this information and advance the PHI. Both indices are formulated in a way that enables their values to be updated as technology and our knowledge about habitable planets, moons, and life advances. Applying the proposed metrics to bodies within our Solar System for comparison reveals two planets in the Gliese 581 system, GJ 581 c and d, with an ESI comparable to that of Mars and a PHI between that of Europa and Enceladus.     

纤维陶瓷复合材料强度和热稳定性的提高

最近研制了一代新型的刚性好重量轻的先进纤维陶瓷复合材料。这类材料在力学性能和热稳定性方面有很大提高。它的抗弯强度是当前能得到的氧化硅纤维绝热材料的2-3倍,而密度减小10％。该材料短时间的重复使用温度高于2600°F,而连续使用温度为2600°F。     

替代惯导陀螺的石英叉

罗克韦尔公司正在采用与数字手表中机构相似的振动石英音叉技术来生产军用战术固态惯性测量装置。这种产品的市场是需要轻小型、低价导航和控制系统,而且数量正在日益增长的战术导弹、精导武器和无人机。 据说新技术更加可靠,但其最大优点是价格较低。数字石英惯性(DQI)测量装置中的6个传感器可采用半导体工业中普通采用的光蚀刻工艺大批生产。罗克韦尔的长期合作伙伴,BEI电子公司西斯特朗·唐纳惯性分公司研制和生产这些传感器。 预计罗克韦尔将以比同等性能光     

一种多平台支持环境

传统的武器系统(如攻击机)利用嵌入式计算机和软件来提供巨大的灵活性和扩展性能。这些性能的实现需要大量的费用，虽然也可用已建立起来的专用软件开发设施来支持这些传统系统。不幸的是这些专用设施的费用一直过高。先进航空电子设备支持多雷达软件研究(AAMRSSS)项目提供了解决上述问题的办法。AAMRSSS研究了用专用软件开发设施(SDF)支持多软件系统平台的可行性。本研究涉及的问题有：通用性；待扩展的新系统的独特要求；平台优先次序以及将来的扩展。本研究特别提出了用F-15的雷达软件开发设施支持AC，130U Gunship(武装直升机)雷达工作的飞行试验计划(OFP)。     

从《宇宙—1500》上雷达观察河水泛滥

在河水泛滥期间研究水泛地的淹没状况并预报在泄洪渠调节的情况下它的变化—这是水文学研究的一个重要方面。在洪水期间,水泛将导致分水界沼泽的部分淹没,而且是产生水泛区沼泽地定期引水的因素之一。水泛地长期的淹没促成了沼泽地需不断引水并促进了水泛地沼泽化过程的发展。河水泛滥对农业、畜牧业、鱼业能源及船泊航运等国民经济部门有影响。这就必须完