Siliceous plankton dominate primary and new productivity during the onset of El Niño conditions in the Santa Barbara Basin, California

The potential for carbon export and the role of siliceous plankton in the cycling of C and N was assessed in natural plankton assemblages in the Santa Barbara Basin, California, by examining uptake rates of inorganic carbon, nitrate and silicic acid. In April–August 1997, the concentrations of chlorophyll a, particulate organic carbon, particulate organic nitrogen and biogenic silica were measured twice monthly, and results revealed the occurrence of at least three blooms, the largest in June. Particulate elemental ratios of C, N and Si were similar to ratios of nutrient-replete diatoms, suggesting that they dominated this bloom. Mean integrated rates of carbon, nitrate and silicon uptake during the 4-month study period are similar to other productive coastal and upwelling regions (103, 8.3 and 13 mmol m⁻² day⁻¹, respectively). New production rates were twice as high as previously reported in this region and indicate that high rates of new production along eastern boundary currents are not confined to the major coastal upwelling regions. C/NO₃⁻, Si/NO₃⁻ and Si/C uptake ratios varied widely, and mean integrated ratios were 14±5.4, 1.6±1.0 and 0.12±0.07 (S.D.), respectively. That mean C/NO₃⁻ uptake ratio corresponds to an f-ratio of about 0.5 indicating a large potential for particulate export. Based on the average Si/NO₃⁻ and Si/C uptake ratios, diatoms could perform all of the primary production and nitrate uptake that occurred during the study; these rates also suggest that export is controlled by diatoms in this system. The mean Si/C biomass ratio was lower than the mean Si/C uptake ratio, consistent with the preferential export of Si relative to C observed in sediment traps in the basin. The study took place during a period of surface-water warming, with nitrate and silicic acid concentrations decreasing throughout the onset of the 1997–1998 El Niño conditions. Although diatoms contributed less to particulate biomass during the low nutrient conditions, high f-ratios (0.33–0.66) were maintained.     

A numerical study of stochastic larval settlement in the California Current system

Key to the predictive understanding of many nearshore marine ecosystems is the transport of larvae by ocean circulation processes. Many species release thousands to billions of larvae to develop in pelagic waters, but only a few lucky ones successfully settle to suitable habitat and recruit to adult life stages. Methodologies for predicting the larval dispersal are still primitive, and simple diffusive analyses are still used for many important applications. In this study, we investigate mechanisms of larval dispersal using idealized simulations of time-evolving coastal circulations in the California Current system with Lagrangian particles as models for planktonic larvae. Connectivity matrices, which describe the source-to-destination relationships for larval dispersal for a given larval development time course, are used to diagnose the time–space dynamics of larval settlement. The resulting connectivity matrices are shown to be a function of several important time scales, such as the planktonic larval duration, the frequency and duration of larval release events and inherent time scales for the coastal circulations. Many important fishery management applications require knowledge of fish stocks on a year-to-year or generation-to-generation basis. For these short time scales (typically less than 1 year), larval dispersal is generally far from a simple diffusive process and the consideration of the stochastic and episodic nature of larval dispersal is required. This work provides new insights into the spatial–temporal dynamics of nearshore fish stocks.     

京沪高速铁路多渠道售票的设计方案探讨

发展多种售票方式,为用户提供更便捷的客票服务成为高速铁路亟待解决的问题。通过京沪高速铁路区域中心客服系统设计,对多渠道售票方式及其实现进行相关研究和探讨。     

Ports and regional development: A spatial analysis on a panel of European regions

This paper analyses the impact of port activities on local development for a sample of 621 TL-3 regions located in thirteen European countries and observed over the period 1998–2009. Using a spatial panel econometric framework which controls for spatial fixed effects, the paper provides an estimate of both the direct and indirect (i.e. spillover) effects associated to port activities. Results suggest that ports might have non-negligible effects on local GDP: interestingly, an important share of the effects takes place outside the region where the port is located.     

基于地域性的北京地铁地面建筑特色研究

从地域性差异和城市文脉延续出发,对北京地铁地面建筑的特色进行了分析研究,并对加强地铁地面建筑特色提出一定的策略,对相关的设计研究具有一定的指导意义.     

提升南通区域经济竞争力的对策研究

文章阐述了区域经济竞争力的内涵及要素,分析了南通区域经济竞争力的优势和不足,并从经济结构战略性调整、增强自主创新能力、促进城乡协调发展、提高资源节约和环境保护水平、促进社会和谐等五方面提出了提升南通区域经济竞争力的对策和方法。     

南通职业教育——区域经济腾飞的助推器

从南通职业教育发展沿革出发,分析其在区域经济发展中的地位和贡献,并对未来南通经济腾飞中,如何把握好机遇,抢占先机,充分发挥职业教育的助推器作用提出战略思路。文章最后指出,提高南通职业教育服务地方经济发展的能力,必须坚持职业教育的科学发展、均衡发展、特色发展。     

广西南宁盆地工程地质特征浅析

文章结合工程实例,对广西南宁盆地区域地质稳定性进行评价。通过划分工程地质组层分别进行岩土体质量评价,进行现场和室内试验,测定岩土体参数并进行优化分析,确定地基设计参数,为工程设计施工提供可靠的依据。     

区域交通流特征提取与交通状态评估方法研究

随着城市各种交通控制系统(UTC)的广泛应用,交通控制中心能够采集大量的交通流数据。通过对这些数据的分析来评价区域的交通运行质量和路口状况,从而有助于改进交通控制方案,这是一项新的研究内容。本文通过对区域内路口大量的检测器数据的分析,利用K均值聚类和EM算法相结合的方法,提取出表征路口交通流运行状况的特征向量。然后,给出典型交通区域内路口交通流运行的平衡因子,建立评价区域内路口相似性的相似性矩阵。利用北京市两个典型交通区域的实际交通流数据进行验证,结果表明该评估模型能够很好的反映北京市交通状况,并具有较好的可移植性。     

城市交通拥挤的动态疏导策略研究

从缓解城市交通拥挤的决策需求出发,对城市交通拥挤的动态疏导策略技术进行了评述。首先根据交通发展的历史归纳出各种拥挤对策．接着根据交通拥挤类型的不同重点分析了2种动态的策略——信号控制和诱导策略的国内外研究现状．指出了存在的问题。进而重点阐述了研究应该改进的方向,并提出了一些策略,最后提出了动态疏导策略的流程图,为城市交通拥挤疏导决策的实际开发提供了基础。