Temporal variability of airborne bacterial community structure in an urban area

Temporal airborne bacterial genetic community structure and meteorological factors were analysed above an urban area in the northwest of France from December 2003 to April 2004 with a sampling strategy considering different time intervals (from an hour to a month). Principal component analysis (PCA) of B-ARISA (Bacterial-Automated Ribosomal Intergenic Spacer Analysis) profiles revealed a hierarchy in the temporal variability of bacterial community: daily<weekly<seasonal. Co-inertia analysis between B-ARISA data and meteorological factors demonstrated the correlation between the seasonal variability in the bacterial community and climatic conditions such as temperature and relative humidity, whereas daily and weekly variability seemed likely to be managed by other factors such as anthropogenic activities.     

The dynamic nature of antipredator behavior: prey fish integrate threat-sensitive antipredator responses within background levels of predation risk

Prey animals often have to face a dynamic tradeoff between the costs of antipredator behavior and the benefits of other fitness-related activities such as foraging and reproduction. According to the threat-sensitive predator avoidance hypothesis, prey animals should match the intensity of their antipredator behavior to the degree of immediate threat posed by the predator. Moreover, longer-term temporal variability in predation risk (over days to weeks) can shape the intensity of antipredator behavior. According to the risk allocation hypothesis, changing the background level of risk for several days is often enough to change the response intensity of the prey to a given stimulus. As the background level of risk increases, the response intensity of the prey decreases. In this study, we tested for possible interactions between immediate threat-sensitive responses to varying levels of current perceived risk and temporal variability in background risk experienced over the past 3 days. Juvenile convict cichlids were preexposed to either low or high frequencies of predation risk (using conspecific chemical alarm cues) for 3 days and were then tested for a response to one of five concentrations (100, 50, 25, 12.5%, or a distilled water control). According to the threat-sensitive predator avoidance hypothesis, we found greater intensity responses to greater concentrations of alarm cues. Moreover, in accordance with the risk allocation hypothesis, we found that cichlids previously exposed to the high background level of risk exhibited a lower overall intensity response to each alarm cue concentration than those exposed to the low background level of risk. It is interesting to note that we found that the background level of risk over the past 3 days influenced the threshold level of response to varying concentrations of alarm cues. Indeed, the minimum stimulus concentration that evoked a behavioral response was lower for fish exposed to high background levels of predation than those exposed to low background levels of predation. These results illustrate a remarkable interplay between immediate (current) risk and background risk in shaping the intensity of antipredator responses.     

交通事故信息管理与时空分布分析

交通事故发生点具有明确的空间位置属性 ,其在空间和时间上的分布具有不均匀性 ,利用GIS技术能实现交通事故信息管理及其时空分布规律的研究。笔者在分析道路交通事故信息的基础上 ,采用全新的管理模式 ,利用空间数据库技术实现交通事故的空间、时间信息以及造成交通事故的人、车、路和环境等因素的一体化管理 ;通过GIS技术进行道路交通事故的时空分布分析 ,发现其在空间和时间上的分布规律 ;最后提出了交通事故管理与分析中需要进一步解决的几个问题。     

Temporal changes in demand for and supply of nests in red bishops (Euplectes orix): dynamics of a biological market

The red bishop (Euplectes orix) is a highly polygynous and colonial weaverbird. Males construct several nests within their territories to which they try to attract females, and females are solely responsible for incubation and raising offspring. In this paper, we describe the characteristics of the red bishop’s mating system as a biological market and investigate the role of nests built by males as a traded commodity in a mating market. As timing of breeding in red bishops in arid and semi-arid zones depends on rainfall patterns which are often unpredictable, there are temporal changes in demand for and supply of nests within a breeding season, with breeding activities of males and females being highly synchronised. We found that males increased their nest-building speed with increased female breeding activity independently of rainfall, indicating that supply follows demand in this mating market. The supply of nests was always larger than the demand for nests. Construction costs for nests increased with demand for nests as indicated by shorter nest-building duration and shorter building delays between two consecutively built nests at times of high breeding activity. Males as a trading class are chosen according to the age of their nests offered, with young nests having a higher probability of being accepted by females. Furthermore, female choosiness with regard to nest age decreased when their own market value decreased, as predicted by biological market theory. The temporal changes of breeding activity together with the female preference for young and fresh nests require that males quickly adjust nest-building activity to varying female demand for new nests. However, males with a better adjustment of building speed to female breeding activity did not gain higher mating success.     

Mating system of the cooperatively breeding noisy miner Manorina melanocephala,as revealed by DNA profiling

In this study we examined parentage within broods of the cooperatively breeding noisy miner using multi-locus DNA profiling. Previous studies of noisy miners described them as highly promiscuous, leading to the suggestion that promiscuous mating behaviour was a tactic used by females to recruit males as provisioners to their nests (Dow 1978). At our study site in south-east Queensland, Australia, we found that both multiple and extra-group paternity (i.e. a female mating with a male outside the group of male provisioners at her nest) were rare. In nests where multiple paternity was possible (i.e. clutch size > 1) 97% of 31 broods were sired by only a single male. Overall, 96.5% of all nestlings (n = 85) were the result of monogamous matings. Also, at the vast majority of nests, the male that sired the nestlings was also the main provisioner among all male nest attendants. Our results show that the mating system of the noisy miner can no longer be considered cooperative polyandry (Brown 1987) but is clearly genetic monogamy. We discuss the implications of this finding for understanding the complex social system of this species.     

2014年宝鸡市大气颗粒物时空分布特征分析

基于2013年12月和2014年全年宝鸡市8个自动空气质量监测子站的PM_(10)和PM_(2.5)的监测数据,探讨PM_(10)和PM_(2.5)的时间分布特征和空间分布特征。结果表明:PM_(10)的日平均浓度为118.23μg/m~3,全年中PM_(10)超过二级标准的天数为80 d,超标率为22%;PM_(2.5)的日平均浓度为68.93μg/m~3,全年中PM_(2.5)超过二级标准的天数为92 d,超标率为25%;PM_(10)和PM_(2.5)的浓度有明显的季节差异。PM_(2.5)和PM_(10)浓度由高到低的季节依次是冬季、春季、秋季和夏季;不同的监测点位中,解放军第三陆军医院监测点位的PM_(10)和PM_(2.5)浓度对于宝鸡市大气颗粒物的污染贡献率相对其他点位较高,主要是其地理位置导致的。     

Accumulation features and temporal trends of PCDDs, PCDFs and PCBs in Baikal seals (Pusa sibirica)

This study investigated the accumulation features and temporal trends of PCDD/Fs, dioxin-like PCBs (DL-PCBs) and non-dioxin-like PCBs (NDL-PCBs) in the blubber of Baikal seals collected in 1992 and 2005. DL-PCBs (480-3600 ng/g) and NDL-PCBs (980-35,000 ng/g) were dominant contaminants. Concentrations of PCDDs and PCBs in males were significantly higher than in females. In males, age-dependent accumulation was observed for PCDDs, mono-ortho PCBs and NDL-PCBs. PCDFs and non-ortho PCBs showed no such trends, implying that exposure of seals to these contaminants has been decreasing in recent years. No decreasing temporal trend was observed for PCDDs, mono-ortho PCBs and NDL-PCBs, suggesting that Baikal seals are still exposed to PCDDs and PCBs. TEQs of PCDDs and mono-ortho PCBs in seals collected in 2005 accounted for 62-77% of total TEQs. The TEQ levels in 40% of the specimens exceeded the threshold level for immunosuppression observed in harbor seals (209 pg/g).     

Dynamics of heavy-metal transfer between biotic (Cytheria chione and Cerastoderma edule) and abiotic (water and sediment) components in marine environment (Bay of Martil, Moroccan Mediterranean coast)

This study deals with the transfer of heavy metals (Hg, Cd, Pb, Cr, Ni, Ti, Zn, and Cu) between abiotic and biotic components (Cytheria chione and Cerastoderma edule) in the inshore intertidal zones of Tetouan/Martil over 2 yr of investigation (1992-1994). Analysis of the heavy-metal accumulation kinetics in Cytheria chione and Cerastoderma edule shows that their highest contents occur during the spring-summer period when an important proliferation of the plankton biomass occurs. However, the accumulation of Cd is higher during the period between winter and spring. In general, heavy-metal concentrations are higher at Cytheria chione than at Cerastoderma edule. These results, according to previous studies, suggest the presence of significant correlations and dynamic reciprocal transfer of heavy metals among seawater, sediment, and molluscs. They also suggest that the level of contamination of decreasing heavy metals follows the sequence: sediment, organisms, and water. Among the molluscs investigated, the variability of the thallium (Tl) contents is difficult to detect due to the very weak presence of this metal in the analysed tissues.     

ITS数据质量控制技术及应用研究

通过总结智能交通系统 (ITS)数据质量控制中所涉及的数据属性 ,提出了ITS数据质量控制算法 :根据阈值理论和交通流理论 ,针对错误数据、丢失数据和不精确数据设计相应的判别规则 ,利用数值计算方法对其进行修正 ,并提出了针对数据中的不规则时间点的修正算法。在对北京市和美国圣安东尼奥市的两组不同时间序列的ITS数据进行实践应用后 ,比较质量控制前后的数据特征 ,证明所提出的算法能够有效地解决数据质量问题 ,提高数据的精确度。最后 ,对国内外ITS数据进行质量控制后的结论和经验作了总结。     

Effects of Land Management Change on Spatial Variability of Organic Matter and Nutrients in Paddy Field: A Case Study of Pinghu,China

The Household Responsibility System initiated in the late 1970s in China has brought a profound change to its rural economy. The shift from the collective farming system to individual family farms has changed land management. The change, including fertilization and crop systems, may have significant effects on soil quality and agro-environmental sustainability. However, very little research is being carried out on the impact of reformed land tenure systems on the spatial variability of soil nutrients. In this study, geostatistics was applied to analyze changes in the spatial variability of soil organic matter and nutrients in paddy fields in Pinghu County, China after 20 years of land management change. In 1984 and 2002, 617 and 131 locations were selected, respectively, for collecting surface soil samples to analyze soil organic matter (SOM), total nitrogen (TN), available phosphorus (AP), and available potassium (AK). From 1984 to 2002, variability of the SOM and TN changed from strongly to moderately spatial-dependent, and the variability of AP remained weakly dependent on space, but that of the AK changed from moderately to weakly spatial-dependent. That the trend of the variability of four soil properties in 2002 became weaker than that in 1984 showed that the extrinsic factors (soil management practices, such as fertilization) weakened the effect by intrinsic factors (soil formation factors, such as soil parent materials) owing to a long period of land management change. The temporal geographic maps of the SOM and nutrients spatial distributions suggested that the concentrations of the SOM and nutrients had been changed to different extents during the period. Significant increase in AP and decrease in AK were noted. The changes were likely due to the imbalance between N, P, and K fertilizers and increased grain yield.