Animal social networks: an introduction

Network analysis has a long history in the mathematical and social sciences and the aim of this introduction is to provide a brief overview of the potential that it holds for the study of animal behaviour. One of the most attractive features of the network paradigm is that it provides a single conceptual framework with which we can study the social organisation of animals at all levels (individual, dyad, group, population) and for all types of interaction (aggressive, cooperative, sexual etc.). Graphical tools allow a visual inspection of networks which often helps inspire ideas for testable hypotheses. Network analysis itself provides a multitude of novel statistical tools that can be used to characterise social patterns in animal populations. Among the important insights that networks have facilitated is that indirect social connections matter. Interactions between individuals generate a social environment at the population level which in turn selects for behavioural strategies at the individual level. A social network is often a perfect means by which to represent heterogeneous relationships in a population. Probing the biological drivers for these heterogeneities, often as a function of time, forms the basis of many of the current uses of network analysis in the behavioural sciences. This special issue on social networks brings together a diverse group of practitioners whose study systems range from social insects over reptiles to birds, cetaceans, ungulates and primates in order to illustrate the wide-ranging applications of network analysis. This contribution is part of the special issue “Social Networks: new perspectives” (Guest Editors: J. Krause, D. Lusseau and R. James).     

A Revealed Preference Approach to Estimating Supply Curves for Ecosystem Services: Use of Auctions to Set Payments for Soil Erosion Control in Indonesia

Abstract:  To supply ecosystem services, private landholders incur costs. Knowledge of these costs is critical for the design of conservation-payment programs. Estimating these costs accurately is difficult because the minimum acceptable payment to a potential supplier is private information. We describe how an auction of payment contracts can be designed to elicit this information during the design phase of a conservation-payment program. With an estimate of the ecosystem-service supply curve from a pilot auction, conservation planners can explore the financial, ecological, and socioeconomic consequences of alternative scaled-up programs. We demonstrate the potential of our approach in Indonesia, where soil erosion on coffee farms generates downstream ecological and economic costs. Bid data from a small-scale, uniform-price auction for soil-conservation contracts allowed estimates of the costs of a scaled-up program, the gain from integrating biophysical and economic data to target contracts, and the trade-offs between poverty alleviation and supply of ecosystem services. Our study illustrates an auction-based approach to revealing private information about the costs of supplying ecosystem services. Such information can improve the design of programs devised to protect and enhance ecosystem services.     

Application of random pore model for SO2 removal reaction by CuO

In this work, mathematical modeling of SO₂ removal reaction with CuO was accomplished by the random pore model. The partial differential equations, describing the reaction of a gaseous reactant with a single pellet and also a packed bed of solid reactant, were solved by the finite element method. The results of modeling consist of CuO conversion-time profiles at different temperatures and SO₂ concentrations, and also break through curves which were compared with the literature experimental data in a good accuracy. The rate constants were estimated from the initial slope of the conversion-time curves, and the product layer diffusivities were evaluated from the whole conversion-time profiles.     

泰山桃花源索道车厢进出站加减速的曲线的分析

通过介绍单线脱挂抱索器客运架空索道关键技术之一的加减速器的原理和作用,分析对比了直线（梯形）加减速曲线和“S”型加减速曲线的优劣。在原设计方图纸数据的基础上,通过对泰山桃花源索道车厢进站和出站加减速曲线的计算,得出实际车厢进站减速曲线和出站加速曲线数据并绘制出图形,同时根据计算得出的实际曲线的特点,结合所分析的直线（梯形）加减速曲线和“S”型加减速曲线的特性,对加减速器相关部件检查维护提出了相应的建议。     

基于IKONOS影像的城市住宅区中水回用空间分布估算

中水回用是解决城市水资源短缺和水环境污染问题的有效途径。开展分散式中水可行性研究,需要考虑中水原水与回用需求的数量、空间分布及平衡关系。论文以南京市住宅区为例,探索了基于IKONOS高分辨率遥感影像分类,估算中水回用空间分布的方法。通过引入单位面积用水定额,将遥感和GIS 分析得到的用地信息与中水原水产量和回用需求关联起来,计算了研究区域中27 个地块的中水原水产量和回用需求量,并分析了两者在空间上的水量平衡关系。结果表明,研究区域存在较大的中水原水供给潜力3.52 L/（m²·d）和较大的利用需求5.37 L/（m²·d）。住宅小区的单位面积原水产量与其建筑容积率成正比;以中高层住宅区为主的地区,中水原水产量能够基本满足本地区的中水回用需求。因此,在这些地区建立分散式污水处理系统,可减少废污水排放,节约自来水取用量,提高水资源利用率。     

Those outsiders: How downstream externalities affect public good provision

Some policy problems pit one group?s interests against another?s. One group may determine provision of a project (such as a dam) that benefits group members but hurts others. We introduce a model of such projects. In-group members may contribute to a common fund that benefits them as a public good. Benefits from the project may vary within the group. Provision has negative downstream externalities: contributions hurt agents outside the in-group (“Outsiders”), rendering them anti-social. Many models of social preferences predict that such externalities should reduce provision, although conditional cooperation or a preference for in-group members may counteract this. We test this model with a lab experiment using Outsiders with whom the in-group members have more and less contact. With homogeneous in-group benefits, the presence of negative downstream externalities reduces contributions by half when they have closer contact with Outsiders but not at all when they have had no contact. We introduce a rotating high-return position that allows subjects to trade favors. In this setting, contributions of non-privileged members diminish slightly when faced with the negative externality given closer contact with Outsiders, and not at all with less contact. Reciprocal giving occurs whether or not Outsiders are present.     

The social cost of carbon revisited

An estimate of the social cost of carbon (SCC) is crucial to climate policy. But how should we estimate the SCC? A common approach uses an integrated assessment model (IAM) to simulate time paths for the atmospheric CO₂ concentration, its impact on temperature, and resulting reductions in GDP. I have argued that IAMs have deficiencies that make them poorly suited for this job, but what is the alternative? I present an approach to estimating an average SCC, which I argue can be a useful guide for policy. I rely on a survey of experts to elicit opinions regarding (1) probabilities of alternative economic outcomes of climate change, but not the causes of those outcomes; and (2) the reduction in emissions required to avert an extreme outcome, i.e., a large climate-induced reduction in GDP. The average SCC is the ratio of the present value of lost GDP from an extreme outcome to the total emission reduction needed to avert that outcome. I discuss the survey instrument, explain how experts were identified, and present results. I obtain SCC estimates of $200/mt or higher, but the variation across experts is large. Trimming outliers and focusing on experts who expressed a high degree of confidence in their answers yields lower SCCs, $80 to $100/mt, but still well above the IAM-based estimates used by the U.S. government.     

The derivation of discount rates with an augmented measure of income

Most developed economies invest in public goods such as national defense, education, infrastructure, and the environment. Discount rates used to evaluate such projects should reflect the rate of return on the current mix of investment opportunities. Rates derived from the productivity of private capital neglect returns beyond the market boundary. The present paper derives discount rates using an augmented measure of national income inclusive of non-market goods. In an empirical application focusing on air pollution and climate damages in the United States economy, the paper reports that the difference between augmented and market discount rates averages 0.3 percentage points from 1999 to 2014.     

ToSIA—A tool for sustainability impact assessment of forest-wood-chains

Within the forest sector, the sustainability concept has evolved from a narrow focus on sustainable wood production to a much broader evaluation of environmental, social, and economic sustainability for whole value chains. A new software tool - ToSIA - has been developed for assessing sustainability impacts of Forest-Wood-Chains (FWCs). In the approach, FWCs are defined as chains of production processes (e.g. harvesting-transport-industrial processing), which are linked with products (e.g. a timber frame house). Sustainability is determined by analysing environmental, economic, and social sustainability indicators for all the production processes along the FWC. The tool calculates sustainability values as products of the relative indicator values (i.e. indicator value expressed per unit of material flow) multiplied with the material flow entering the process. Calculated sustainability values are then aggregated for the segments of the FWC or for the complete chain. The sustainability impact assessment requires carefully specified system boundaries. ToSIA uses a data-oriented approach that is very flexible in the focus of the analysis and the selection of indicators of sustainability. An example of alternative Norway spruce management systems in Southern Germany and their effects on six sustainability indicators is presented. The less intensive management system with natural regeneration and motor-manual harvesting shows higher carbon storage and slightly less energy use. It creates more employment and higher labour costs, but the average rate of accidents is also higher. ToSIA offers a transparent and consistent methodological framework to assess sustainability impacts in the forest-based sector as affected, e.g. by changes in policies, market conditions, or technology. The paper discusses strengths and limitations of the approach and provides an outlook on further development perspectives of the methodology.     

Social network properties within a fish assemblage invaded by non-native sunbleak Leucaspius delineatus

Network theory is commonly used to reveal social interactions and the organisation of interconnected nodes—but has not yet been applied to animal invasions. Non-native species invasions are now considered one of the foremost threats to natural ecosystems and biodiversity. This is the first attempt to assess social network properties within a freshwater fish assemblage invaded by a non-native fish species. We show that invasive sunbleak Leucaspius delineatus is socially more strongly interconnected with native species than the native species with each other. The social networks also reveal characteristics of a ‘small world’ such as low clustering coefficients C and short path lengths L. The findings may indicate potential traits of successful invaders and the implication for the spread of pathogens between individuals within a group of animals that contain a non-native invasive species. The success of establishment and subsequent invasion may be highlighted not only by the capacity of the new species to adapt to the new environment, but also in its capacity to penetrate the social circle of the native community.