Influence of low and decreasing food levels on Daphnia-algal interactions: Numerical experiments with a new dynamic energy budget model

Based on numerical experiments with a new physiologically structured population model we demonstrate that predator physiology under low food and under starving conditions can have substantial implications for population dynamics in predator-prey interactions. We focused on Daphnia-algae interactions as model system and developed a new dynamic energy budget (DEB) model for individual daphnids. This model integrates the κ-rule approach common to net assimilation models into a net-production model, but uses a fixed allocation of net-productive energy in juveniles. The new DEB-model agrees well with the results of life history experiments with Daphnia. Compared to a pure κ-rule model the new allocation scheme leads to significant earlier maturation at low food levels and thus is in better agreement with the data. Incorporation of the new DEB-model into a physiologically structured population model using a box-car elevator technique revealed that the dynamics of Daphnia-algae interactions are highly sensitive to the assumptions on the energy allocation of juveniles under low food conditions. Additionally we show that also other energy allocation rules of our DEB-model concerning decreasing food levels and starving conditions at the individual level have strong implications for Daphnia-algae interactions at the population level. With increasing carrying capacity of algae a stable equilibrium with coexistence of Daphnia occurs and algae shifts to limit cycles. The amplitudes of the limit cycles increase with increasing percentage of sustainable weight loss. If a κ-rule energy allocation is applied to juveniles, the stable equilibrium occurs for a much narrower range of algal carrying capacities, the algal concentration at equilibrium is about 2 times larger, and the range of algae carrying capacities at which daphnids become extinct extends to higher carrying capacities than in the new DEB-model. Because predator-prey dynamics are very sensitive to predator physiology under low food and starving conditions, empirical constraints of predator physiology under these conditions are essential when comparing model results with observations in laboratory experiments or in the field.     

Analysis of the global warming dynamics from temperature time series

Global warming is the observed increase of the average temperature of the Earth. The primary cause of this phenomenon is the release of the greenhouse gases by burning of fossil fuels, land cleaning, agriculture, among others, leading to the increase of the so-called greenhouse effect. An approach to deal with this important problem is the time series analysis. In this regard, different techniques can be applied to evaluate the global warming dynamics. This kind of analysis allows one to make better predictions increasing our comprehension of the phenomenon. This article applies nonlinear tools to analyze temperature time series establishing state space reconstruction and prediction. Since noise contamination is unavoidable in data acquisition, it is important to employ robust techniques. The method of delay coordinates is employed for state space reconstruction and delay parameters are evaluated using the method of average mutual information and the method of false nearest neighbors. Afterwards, the simple nonlinear prediction method is employed to estimate temperatures of the future. Temperature time series from different places of the planet are used. Initially, the approach is verified considering known parts of the time series and afterwards, results are extrapolated for future values estimating temperature until 2028. Results show that these techniques are interesting to estimate temperature time history, presenting coherent estimations.     

钻井废弃液中石油污染物及细菌生态多样性

采用GC/MS分析方法,发现平湖油田钻井废弃液中含有烃类、酸类和酯类等23种有机污染物质,含量达到49 800 mg/L。运用16S rRNA基因分析法测得的微生物生态多样性表明,废弃液中微生物种类丰富,包括γ和β变形杆菌,γ-Proteobacteria是优势菌群,占克隆总数78.6%。Oceanospirillales、Pseudomonadales和Enterobacteriales是γ-Proteobacteria纲的主要菌群。     

An Observation Method for Analyzing Operators’ Routine Activity in Computerized Control Rooms

An activity analysis method was developed for studying the structure and dynamics of control room operators’ activity during normal operation based on directly observable elements of the operators’ behavior. The method assesses current activity along three dimensions in each 5-min period of the shift. Intensity characterizes arousal level, direction shows whether the activity is directed predominantly at the process control task, at something else, or miscellaneous. Motivation reflects if the activity is driven by intrinsic or extrinsic motivation. A case study is presented, in which 3 morning, 3 afternoon, and 3 night shifts of a Nuclear Power Plant operator crew are involved. The obtained results gave a deeper understanding of the operators’ activity and also revealed an “arousal compensation” tendency.     

地震应急避难需求的系统动力学研究

为定量研究地震应急避难人群的规模及变化规律,建立需求分析的系统动力学模型。该模型包括建筑物倒塌,断水和电梯停运3种因素造成的需求。参考汶川地震中板房建设速度和电梯修复速度,以及日本关于地震断水率的研究成果,建立非线性模型拟合各需求的变化规律。采用Vensim软件建立系统动力学模型,分析各需求的综合变化规律。采用上海市徐汇区的数据进行案例演算,并与其他研究方法对比分析仿真误差。仿真结果表明:建筑物损坏对人群数量的影响很大,但是灾后1个月内断水的影响最大;相对于工程技术因素,人因对需求有重要的影响。     

Do Polynomials Adequately Describe the Hypsometry of Monadnock Phase Watersheds?

Hypsometry has been shown to be a useful tool in geomorphic analysis of watersheds with the use of third‐degree polynomial equations to express the hypsometric curve. Despite its usefulness with watersheds in the equilibrium stage, the third‐degree polynomial has been found to be inadequate to describe the hypsometry of Monadnock phase watersheds. Three other equations — a modified third‐degree polynomial with a rational term, a sigmoidal model, and a double exponential — were used to determine hypsometric attributes of 32 Monadnock phase watersheds and compared to the third‐degree polynomial form. The three other equations were found to be better fits for Monadnock phase watersheds than the third‐degree polynomial equation, regardless of which ratio — area or elevation — was plotted as the independent variable. Due to the occasional failure of each functional form to give logical values for hypsometric attributes, the importance of using more than one form equation is discussed. After determining the best‐fit equation for each watershed, the usefulness of hypsometric attributes is discussed in relation to erosion processes within Monadnock phase watersheds.     

印刷线路板的超临界流体分离实验

目前印刷线路板(Printed Circuit Board, PCB)的资源化循环利用方法存在材料回收率低和环境污染的不足,采用一种新的超临界流体技术对PCB中的金属及其它成分进行分离处理,在采用丙酮、CO2及Lewis-酸的混合介质及优化的温度和压力反应条件下,获得了90%的金属回收率,高于目前的机械破碎分选实验结果.该方法为线路板的资源化循环再利用提供了一个新的有效选择.     

Dynamics of the Coordination of Economy-Society and Resource-Environment in Shandong Peninsula,China

Abstract

Shandong Peninsula, as a more developed region in Shandong Province even the east coast of China, is facing challenges from resources and environment pressures. This paper tried to track and assess the coordination status and the dynamic between resource-environment and economy-society systems in Shandong Peninsula during 2001—2008 in order to provide decision support for regional sustainability. An appraisal index system was built including five aspects of harmony degree (A), sustainability degree (B), opening degree (C), stability degree (D) and controllability degree (E). The results showed that: 1) The coordination level of resource-environment and economy-society in Shandong Peninsula has continuously grown, and it has undergone three stages: no coordinated degree (2001–2002), weak coordinated degree (2003–2006) and basically coordinated degree (2007– 2008). 2) Five indexes of criterion hierarchy also increased overall, but each index showed different trends. Harmony degree, sustainability degree and opening degree rose all the time, while stability degree and controllability degree alternately rose and fell. The improvement of controllability degree was the slowest. 3) The aggravating trend of environmental pollution was slowing down. The economic growth was driven by industrial growth and urbanization typically and investment was still the main force to pull the regional economic growth. At the same time, technology and education were becoming more and more important for economic growth. The level of foreign capital utility declined and the geographical advantage of Shandong Peninsula was exerted. Meanwhile some characteristics of knowledge economy were presenting. Water resources become the main constraint factor of fast development in Shandong Peninsula. It is necessary to further strengthen the coordination ability of government on regional sustainable development.     

System dynamics modeling for municipal water demand estimation in an urban region under uncertain economic impacts

Accurate prediction of municipal water demand is critically important to water utilities in fast-growing urban regions for drinking water system planning, design, and water utility asset management. Achieving the desired prediction accuracy is challenging, however, because the forecasting model must simultaneously consider a variety of factors associated with climate changes, economic development, population growth and migration, and even consumer behavioral patterns. Traditional forecasting models such as multivariate regression and time series analysis, as well as advanced modeling techniques (e.g., expert systems and artificial neural networks), are often applied for either short- or long-term water demand projections, yet few can adequately manage the dynamics of a water supply system because of the limitations in modeling structures. Potential challenges also arise from a lack of long and continuous historical records of water demand and its dependent variables. The objectives of this study were to (1) thoroughly review water demand forecasting models over the past five decades, and (2) propose a new system dynamics model to reflect the intrinsic relationship between water demand and macroeconomic environment using out-of-sample estimation for long-term municipal water demand forecasts in a fast-growing urban region. This system dynamics model is based on a coupled modeling structure that takes into account the interactions among economic and social dimensions, offering a realistic platform for practical use. Practical implementation of this water demand forecasting tool was assessed by using a case study under the most recent alternate fluctuations of economic boom and downturn environments.     

Ethnobotany and ecological perspectives on the management and use of plant species for a traditional fishing trap, southern coast of São Paulo, Brazil

The cerco-fixo is an artisanal fishing trap widely used by traditional communities in the estuarine region of the southern coast of the state of São Paulo, Brazil. The primary goal of the study was to investigate, through ethnobotanical and ecological approaches, the use of plant species by traditional fishermen to build the cerco-fixo at Cardoso Island State Park and Cananéia Island. Ethnobotanical data were collected through interviews, direct observation, plant collection and identification, and document analysis. An ecological evaluation was also done comparing five 20 × 20 m plots in a managed area to five 20 × 20m plots in an unmanaged area, both within arboreal sandy soil vegetation called restinga arbórea, found within the Brazilian Atlantic Forest domain. This study involved 34 fishermen living at Cardoso and Cananéia Islands. The fishermen know more than 90 Atlantic Forest plant species that can be used to build the cerco-fixo. Tree species from the family Myrtaceae were the most quoted in the interviews. With respect to the ecological evaluation, the cluster analyses showed greater heterogeneity in terms of floristic composition (i.e. greater floristic dissimilarity) within the plots of the managed area. The analyses of diversity showed a slightly higher species richness and slightly lower values for Shannon, Simpson, Hurlbert’s PIE and Evenness indices in the managed area (59 species; H′ = 3.28; 1/D = 10.77; E = 0.80; Hurlbert’s PIE = 0.91) compared to the unmanaged area (54 species; H′ = 3.39; 1/D = 20.21; E = 0.85; Hurlbert’s PIE = 0.95). The Hutcheson’s t test showed no significant difference between both areas’ Shannon diversity indices (t: −1.04; p: 0.30). These results are attributed to the greater dominance of the palm species Euterpe edulis Mart. in the managed area (28.2% of the trees sampled at this area; n = 118), which equals twice the percentage of individuals of the same species found for the unmanaged area (14.6% of the sampled trees; n = 48). We discuss the impact of the fishermen’s harvesting practices in the managed area with an emphasis on three main points: (1) the harvesting practices are likely not contributing to a decrease in diversity in the managed area; (2) the greater heterogeneity in terms of floristic composition found for the managed area may reflect a mosaic pattern created by the opening of small tree-gaps distributed across this area over the course of more than 50 years; (3) the disturbance promoted by the fishermen’s harvesting practices can be compared to natural disturbances of low impact that create mosaic patterns in tropical forests. This study emphasizes the prominence of the human dimension in ecological processes and the importance of considering the perspectives of local people when discussing the conservation of the natural environments in which these people live.