Isotopic variation (δN, δC,and δS) with body size in post-larval estuarine consumers

Stable isotope analyses were conducted on fish and crabs in Apalachicola Bay, Florida (USA) to determine whether δ¹⁵N values are correlated with length within these species. Our objective was to define the smallest trophic unit of the system as a prelude to further isotopic evaluations of consumer trophic level in Apalachicola Bay. In some cases, the smallest trophic unit is the individual species; however, previous gut content analysis on organisms in this system indicated that subdivision by size class within species might be required. However, over the size ranges observed, there was no systematic change in the δ¹⁵N values of individual consumers. Analysis of the δ¹³C and δ³⁴S values of these species reveal no obvious shifts in the utilization of organic matter sources with length that could be obscuring a trend in the δ¹⁵N signal. We find no isotopic evidence for a systematic trophic level increase within the species examined over the size ranges observed in this estuary. These results indicate that species rather than size class is the best predictor of trophic habit among these Apalachicola Bay consumers.     

Feeding of Aurelia sp. (Scyphozoa) and links to the microbial food web

The impact of the scyphomedusa Aurelia sp. on planktonic assemblages was experimentally studied in enclosures incubated in situ in the sea lake of Mljet Island (Big Lake, Southern Adriatic), where jellyfish are present throughout the year. In situ feeding experiments using plankton at natural densities indicated a reduction in abundance for small calanoid and cyclopoid copepods, copepodites, nauplii and ciliates in the presence of Aurelia sp. In addition to direct predatory pressure, Aurelia sp. exerted an indirect cascading effect on autotrophic and heterotrophic microbial plankton. Phytoplankton biomass increases of up to 0.5 μg C·l^?1·h^?1 were mainly related to 19′‐hexanoyloxyfucoxanthin‐ and 19′‐butanoyloxyfucoxanthin‐containing phytoplankton. Bacterial production was about twice as high in the presence of Aurelia sp. and biomass was also consistently higher. It appears that the top‐down effect of predation along with material release by Aurelia sp. results in increases in microbial biomass and production.     

A preliminary investigation of the fish food web in the Gironde estuary,France, using dietary and stable isotope analyses

Carbon and Nitrogen stable isotopes and stomach contents analyses were used to investigate an estuarine fish food web and identify the contribution of these two methods to the knowledge and understanding of the food web's structure and its functioning. The nine most abundant fish species during the warm period in the Gironde estuary (southwest France, Europe) are examined. Observation of the stomach contents reflects a variety of feeding modes between fish species that consume a diverse assortment of prey, with limited dietary overlap. Nevertheless, when regarding the whole fish community, few prey species dominate the stomach contents. Nitrogen isotope ratios indicate a high intraspecific variability inducing an interspecific covering of the signatures. However, a tendency to δ¹⁵N enrichment according to the trophic position of the species studied was observed. Fish assemblages show a trend towards enrichment of their carbon isotopic signatures from the upper estuary (−20.8 ± 1.8‰) towards the lower estuary (−18.3 ± 1.6‰). But whatever the capture zone considered, most of the individual δ¹³C values for each fish analysed are comprised between −22 and −16‰. Only few specimens, belonging to migratory amphihaline species, have significantly lighter values.     

北冰洋航海线在世界地图上的表示及相关讨论

介绍根据《系列世界地图》提出的“北冰洋是世界地中海”的新观念,讨论了全球变暖后北冰洋凸显出的战略意义。通过对东京到伦敦的“苏伊士航海线”、“巴拿马航海线”、“好望角航海线”和“北冰洋航海线”的对比分析,展现“北冰洋航海线”表示在“北半球版世界地图”上的优越性。     

一种基于Web Services的事务流中间件模型

介绍事务工作流，实现了Web服务组合的可靠和自动完成。将传统的事务工作流模型应用到Web服务的特殊环境下，提出基于Web Service的事务流模型WSTW，并设计了可扩充的事务流中间件。最后给出WSTW模型的一个实现。     

基于Internet技术的省级预报产品平台

本文首先介绍了ASP的特点和编程中的对象，在分析ASP访问Web数据库原理的基础上详细论述了实现步骤，并结合实例来说明ASP的应用。     

全球化时代的地缘政治形态分析

地缘政治形态是由各种地缘政治关系有机组合而形成的综合体,它反映特定时空条件下地缘政治现实的总体面貌和特征。本文在简要介绍地缘政治形态概念和研究方法基础上,着重剖析当今世界以全球化为特征的地缘政治形态的内部结构。全球化打破了以往以民族国家为基本单元的地缘政治结构,表现出明显的多元化趋势;同时,国家之间边界越来越模糊,相互依赖日渐加深,地缘政治的全球整体性进一步加强,世界地缘政治形态展现出新的风貌。     

大数据时代城市时空间行为研究方法

信息技术的快速发展带来了“大数据”时代的到来,改变了城市的空间组织和居民行为,并使得城市时空间行为研究方法面临变革。本文在总结传统城市时空间行为研究方法存在问题的基础上,对影响其变革的数据获取与处理技术进行梳理,重点从居民时空行为、城市空间及城市等级体系3个方面综述了国内外应用大数据进行城市时空间行为研究的最新进展,构建了基于大数据应用的城市时空间行为研究方法框架。本文认为,大数据时代城市时空间行为研究方法的变革主要取决于对反映居民时空行为的网络或移动信息设备数据的挖掘、处理及应用,但是还需要进一步推动相关学科间的交叉与融合,加强社交网站等网络数据在居民时空行为和城市空间研究中的应用,并指导城市规划编制与管理方法的创新。     

云南石林景区主要乡土植物物候特征的初步研究

为掌握石林景区主要乡土植物物候节律,选择25科35种乡土植物,对其物候特征与同期主要气象因子进行了2 a平行观测。结果表明,在2月气温达到10℃,有46%的植物开始萌动;3月气温持续增高并超过15℃,展叶的植物最多,占57.1%;开花期集中在3~6月,尤其在5月温度超过20℃,有82.9%的树种开花;果实成熟期则分散在4~12月。各个物候期的平均温度和≥5℃积温与植物物候表现较为密切,光照和温度对植物开花和结实期影响较大。根据乡土植物物候特征,结合喀斯特山地自然景观特点和景区适配植物群落建设,提出“石中有树,树中有石”的配置原则,筛选在时空格局上适应喀斯特山地环境的观赏植物,构建出与石林喀斯特景观相协调的植被景观,增加景区景观和生态价值,提升景区的内涵。     

宽叶螺旋钻中风压钻进技术在晋城某矿的应用

针对觜城某矿井下沿煤层瓦斯抽采钻孔在施工过程中遇到煤层含水量较大时,孔内返风不畅,排粉效果差,影响钻孔孔深和成孔率等问题,采用宽叶片螺旋钻杆巾风压钻进工艺及试验。现场试验证明该工艺在含水量较大的煤层沿煤层瓦斯抽采（放）孔钻进施工中较为理想,值得推广。