Swimming with mermaids: Communication and social density in the Second Life merfolk community

While individuals are solicited by a growing number of online networks and virtual communities, human cognitive resources are still limited in terms of the number of fruitful interactions a given individual can sustain. With a high degree of competition for attention, affiliation with the community and communication between its members are central for the survival of virtual communities. A particular virtual community could shed a new light on these phenomena. Indeed, beside the conventional communities based on human-like land-dwelling avatars, a merfolk community spontaneously emerged in the seas of the virtual world of Second Life. The fact that merfolk avatars characteristics strongly restrain their interactions with others and their ability to simultaneously join other communities obviously impacts the structuring and communication within the merfolk community. In order not to become isolated, the members have to develop optimal strategies to keep strong bonds, which in turn reinforce the immersion process. The Second Life merfolk community therefore provides an ideal model to study how members of a virtual community can compensate for ultra-specialization by increasing the quality of the internal communication processes within the community. Furthermore, the observation of the merfolk virtual community demonstrates how optimizing communication, even in a community with a wide repartition and low actual density within the virtual world, can reinforce social density.     

面向大规模网络的快速重叠社团挖掘算法

重叠社团在社交网络大数据中普遍存在.针对现有重叠社团挖掘算法易将重叠区域错误地划分为独立的社团且计算复杂的问题,提出了一种基于局部信息度量的快速重叠社团挖掘算法（Local information based Fast Overlapped Communities Detection,Li-FOCD）.首先,为节点定义局部信息度量指标——社团连接度和邻居连接度,建模节点与社团的关系,缩小了计算范围;然后,每次并行地迭代执行缩减、扩展、去重等操作,并更新局部度量指标,通过松弛每次迭代的终止条件,发现近似最优社团集合而不是最优社团,最终算法复杂度为O（m+n）.基于真实的大规模社交网络数据的试验分析表明：与当前流行的重叠社团挖掘算法相比,Li-FOCD在不损失检测质量的前提下,大幅提升了计算效率.     

基于网络嵌入方法的肠道微生物组大数据网络分析

厘清菌群群落与环境的相互关系及其潜在的驱动机理是肠道微生物研究的一项关键任务。通过微生物组高通量测序和大数据分析辨识微生物组分及功能是目前微生物群落分析的主要方法。现有人体肠道微生物的研究主要侧重于描述肠道菌群多样性和组成特征,缺少更深层次的菌群内部互利共生关系及其生态演替的探索。如何由微生物组数据从分子网络角度来研究肠道菌群分布的关联模式是目前亟待解决的问题。该文使用机器学习领域的网络嵌入方法改进传统生物网络结构学习技术过于依 赖节点间的个体相关关系的弊端,更准确地捕捉微生物网络关联的异构性、隐变量和不均衡性等特征。通过对生成的模块与环境变量以及关键代谢物的进行相关性分析,证实了新的网络模块挖掘方法可以更好地提取肠道菌群结构中之前较少被认识到的特征模块,从而更好地评估菌群与菌群之间、菌群与环境之间的制约关系以及菌群代谢功能之间的潜在耦合机制。该研究中描述的方法不仅给肠道微生物群落结构的解析提供了新视角,还可以拓展应用到其他环境微生物领域的研究,通过数据的多阶信息更好地反映群落结构的驱动过程。     

Potential of Bayesian networks for adaptive management in water recycling

Water recycling is an important solution to increasing water scarcity. However, universal wastewater treatment standards deter uptake of recycling schemes. Lack of data also impedes fit-for-purpose water recycling and water managers are challenged by decision making under uncertain conditions. Bayesian networks (BNs) are increasingly recognised as a valuable tool for decision making under uncertainty. In this study BNs are used to model health risks associated with wastewater irrigation of a public open space. Three BNs based on quantitative microbial risk assessment model risk reduction potential along a treatment chain and at the site of reuse. The BNs simulate multiple exposure profiles and scenarios, providing conditional probability of infection or illness, comparable with health-based targets. Study findings highlight the significant impact of post treatment risk mitigation, despite challenging conditions. BNs provide a transparent, defensible evidence base for mapping and quantifying risk pathways, comparing decision options and predicting outcomes of management policies.     

高效苯酚降解菌群的选育及降解特性研究

通过富集驯化获得具有高效降解苯酚能力的苯酚降解菌群PDBC-1,对菌群降解苯酚的性能及影响因素进行了分析。结果表明,红球菌属细菌是该菌群中的优势菌种。在初始苯酚质量浓度低于1 200mg/L时,菌群能够在72 h内完全降解苯酚,但在更高苯酚浓度下,苯酚对菌群生长造成明显抑制,苯酚降解能力显著下降。该菌群降解苯酚的适宜盐度为0~5%,温度为25~40℃,pH为7.0~8.0。     

快速吸水响应性PVA/HEC多孔复合材料的制备及性能

将酵母菌作为微生物发泡剂引入到聚乙烯醇(PVA)/羟乙基纤维素(HEC)复合材料中,结合循环冷冻-解冻法制备PVA/HEC多孔复合材料。测试了不同实验条件下PVA/HEC多孔复合材料的孔隙率、吸水性、保水性。通过FTIR和SEM表征样品的微观结构;采用热重分析仪(TG)、X射线衍射仪(XRD)、万能拉力试验机分析样品热稳定性、结晶性、力学性能。结果表明:酵母菌发泡PVA/HEC多孔复合材料孔呈大孔套小孔的椭圆状开孔结构,具有快速吸水响应性;保水性良好,24 h后保水率降至最低;与PVA/HEC复合材料相比,PVA/HEC多孔复合材料热稳定性和力学性能均有所提高,压缩强度和极限抗压应力分别是13.2、6.4 MPa。     

一种陆基微生物燃料电池供电的无线传感器网络

Aquatic Microbial Fuel Cell(AMFC) must be inoculated and work in water environment. Terrestrial Microbial Fuel Cell(TMFC) can overcome the shortcoming. In order to realize the practical application of TMFC, a single-hop Wireless Sensor Network(WSN) powered by a TMFC experimental setup is designed and established. Power generation performance of the TMFC and sensor data acquisition, wireless transmission and processing of the WSN are tested by experiments. Experimental results show that the proposed TMFC can drive the single-hop WSN periodically, which validates the feasibility of TMFC powered WSN.     

可溶性微生物产物对偶氮染料废水脱色及产电性能的影响

可溶性微生物产物(Soluble Microbial Product,SMP)是活性污泥污水处理体系中的微生物的重要代谢产物,是污泥絮体形成以及保证体系稳定运行的关键因素之一.本文对CASS和A2O工艺产生的脱水污泥进行了好氧和厌氧培养,提取了SMP和胞外聚合物(Extracellular Polymeric Substances,EPS),表征并探究了两者对含偶氮染料废水的微生物燃料电池产电性能的影响,以及对脱色效率的改善情况.红外分析表明,不同工艺和培养方法得到的SMP和EPS的成分构成相似度很高;PACl沉降试验表明,SMP中的大分子物质含量普遍低于EPS.SMP和EPS均可提升微生物燃料电池的电压,最高可达130mV,且两者均可提高偶氮染料的脱色率,最高可达93%.这些研究表明SMP和EPS有作为染料废水产电资源化助剂的价值.     

石油降解单菌株及混合菌降解产物分析

从中国石油长庆石化公司附近的油泥中分离筛选出4株石油降解菌,用于组建降解原油的混合菌体系.在等接种量培养条件下,单菌株对石油烃的降解率达到41.83%~54.87%,而混合菌降解效率高于单菌株,达到64.27%.不同微生物在降解过程中起着不同的作用.居植物柔武士菌(Raoultella planticola)具有脱烷基功能,对一些支链烃有降解效果;蜡状芽孢杆菌(Bacillus cereus)既可以氧化末端烯烃,又可以降解环烷烃;克雷伯氏菌(Klebsiella variicola)是优势菌种,不仅具有以上3种降解功能,还可以降解炔烃;粘质沙雷氏菌(Serratia marcescens)和蜡状芽孢杆菌(Bacillus cereus)均能氧化不饱和醛基.4种单菌株可能存在相互抑制作用,不宜混合培养降解环烷烃.本研究为石油烃的降解机制和筛选功能微生物等方面奠定了理论基础.     

Search for potent attractants of onion flies

Of various chopped vegetables tested,Allium spp. high in propyl-containing alkyl sulfides (e.g.,cepa group) caught the most onion flies in trapping tests in the field. Fly catches to chopped onion increased with bait quantity. Attractancy of chopped onion changed dramatically during aging in the field; catch increased over the first few days, peaked at ca. fivefold over fresh material by 3–5 days, and then declined sharply. This age-dependent increase in attraction was not seen for garlic (known to have antimicrobial properties) nor with chopped onion mixed with chopped garlic. These data suggested that attraction of onion flies to onions was strongly influenced by microbial activity associated with decomposing onions. The bacteriumKlebsiella pneumoniae was identified as a major colonizer of onions maximally attractive to onion flies. This increased attraction is not due to the previously reported microbially produced volatiles ethyl acetate and tetramethyl pyrazine.Diptera: Anthomyiidae.Paper No. 11047 of the Michigan State University Agricultural Experiment Station.