Heterogeneity in Economics

This paper argues that heterogeneity of agents’ characteristics plays a fundamental role in the economy and should do so in economic models. Three aspects are considered. Firstly the notion that assuming heterogeneity was a solution to the problem posed by the results of Sonnenschein Mantel and Debreu is considered and it is suggested that the more pragmatic approach adopted by Hildenbrand is likely to be more productive. Next the role of adaptation and evolution which necessarily involve variety or heterogeneity is examined. It is suggested that heterogeneity will persist since agents will only slowly learn to adapt and that in the meantime the environment will change. Lastly the role of heterogeneity in financial markets is examined. It is suggested that heterogeneous and varying expectations may account for many of the stylised facts which do not seem to be consistent with the standard financial markets model.“Variety is the spice of life”     

基于Repast平台的城市交通系统仿真建模研究

提出了采用基于Agent的仿真建模方法为研究人员提供了城市交通系统研究新的思路，Repast平台则可以支持研究人员对复杂适应系统快速地建模。介绍了Repast仿真平台的结构、主要类库及建模步骤，并结合城市交通系统中提供交通信息服务的实例，简要阐述了使用Repast仿真平台对城市交通系统进行建模的过程。     

Adaptive responses to landscape changes from onshore wind energy development in the Republic of Ireland

Covering 26 years of Irish onshore wind energy development, this article tracks patterns in landscape changes from wind farm construction and identifies adaptive responses in public policy and by stakeholder groups. Wind farms face well-documented challenges with social acceptance due to landscape changes; however, little research has examined interactions between landscape change and social adaptations over the long-term. This article systematically reviews 20 policy documents, undertakes spatio-temporal linear modeling of 212 wind farms using 9 landscape change metrics, and analyzes 5 stakeholder group interviews on adaptive responses to landscape changes. Upward trends occur in turbine height, impact accumulation, placement in agricultural landscapes, construction delays, and new farms built per year. Downward trends occur in the number of turbines per farm, visual disruption of protected areas, and placement in wetlands. Key patterns in stakeholder groups’ adaptations include conflicting interpretations of landscape amenities and evolution, and expanded community outreach, networking, and public participation after exposure to infrastructure. Stakeholders adapt to existing infrastructure separately from adapting strategies to respond to new wind farms. Overall, a mutual relationship emerges wherein landscape changes from wind farms respond to policies and stakeholder activities, while policies and stakeholder groups adapt to the physical realities of landscape change.     

Farmers’ perspectives on climate change manifestations in smallholder cocoa farms and shifts in cropping systems in the forest-savannah transitional zone of Ghana

The study was conducted to explore actual manifestations of climate change in smallholder cocoa farms to aid extension response to climate impacts, and to understand the reasons for a renewed interest in cocoa production in the forest-savanna agro ecological landscape in Ghana, in spite of unfavorable climatic conditions. Two hundred cocoa farmers were interviewed in nine cocoa farming communities. Selected farms were also visited to document on-farm manifestation of climate impacts as well as innovations and strategies farmers are employing to respond to the adverse impacts of climate change on their cocoa systems. The results revealed various manifestations of climate impacts on cocoa farms which included, increased incidence of pests and diseases, wilting of cocoa leaves, high mortality of cocoa seedlings which affected expansion and farm rehabilitation, and wilting of cherelles resulting in low yield. The farmers maintained that their response to the immediate impacts of climate on cocoa was a shift to cereals due to the unpredictable climatic patterns and the shortened duration of rainfall. However, a combination of storage and supply chain challenges and low returns from cereal production, coupled with land scarcity in the Western Region, where most of them are migrant farmers accounted for their decision to return to cocoa production lately. It was observed, among other adaptive responses, that some farmers plant about three times the plantain suckers they usually plant, to provide a dense temporary shade over cocoa seedlings, and resort to planting more cocoa seedlings randomly per unit area on new farms, contrary to recommended planting approach, as a form of insurance against seedling mortality. More importantly, a community-based fire response system was identified to be a major safeguard mechanism to the threat of fire. Clearly, the farmers are not replanting cocoa in the forest-savanna agro ecological landscape because it is more productive than cereals, but they believe that a low yielding cocoa is far better than a productive cereal cropping systems that offer low returns when compared to cocoa. The study brings out the sustainable livelihood challenges of the rural farmer within the context of a changing climate for appropriate policy response.     

Countermeasures of adaptation to climate change： establishment and application for implementation matrix

In the conceptual framework of adaptation policy assessment to climate change, adaptation measures can be categorized as two groups：facilitation and implementation. Facilitation measures refers to activities that enhance adaptive capacity, while implementation refers to activities that actually avoid adverse climate impacts on a system by reducing its exposure or sensitivity to climatic hazards, or by moderating relevant non-climatic factors. This paper aims to establish a matrix of implementation measures of adaptation to climate change, through four different ways how adaptation can influencc the relevant elements of climate change. reducing the exposure, reducing the sensitivity, alleviating the adverse impacts and reducing the negative non-climatic factors, and then further discuss the particular implementation measures of adaptation to climate change, through application studies on the selected sub-systems, intend to organize the disordered implementation measures in existent, and put forward some new measures under the guidance of this matrix, which could enrich and promote the system and content of implementation measures of adaptation.     

英语标点符号用法浅析

熟练应用英语标点符号需要掌握其用法。常用的英语标点符号共15个。本文对这些标点符号的用法作了一一分析，旨在对英语学习者能清楚的认识英语标点符号的用法起到作用。     

Farmers’ risk preferences and their climate change adaptation strategies in the Yongqiao District,China

Farmers’ risk preferences play an important role in agricultural production decisions. This study characterizes risk preferences among farmers in Yongqiao and determines how these risk preferences are related to their choices regarding climate change adaptation strategies. We find that most farmers in the study area were aware of climate change. They were taking measures to protect their livelihoods against perceived changes to the local climate. The risk experiment result shows that the representative subject was risk averse, and women were more risk averse than men. The relationships between farmers’ risk preferences and different climate change adaptation choices were different. Farmers’ risk aversion was negatively and significantly related with adaptation strategies on planting new crop varieties and adopting new technology, but it had a significantly positive effect on purchasing weather index crop insurance. The results also indicate that the level of education, farming experience, farm size, household income and perception of climate change impacts influence farmers’ adaptation decisions.     

Reconciling sustainability, systems theory and discounting

Most definitions of sustainability imply that a system is to be maintained at a certain level, held within certain limits, into the indefinite future. Sustainability denies run-away growth, but it also avoids any decline or destruction. This sustainability path is hard to reconcile with the renewal cycle that can be observed in many natural systems developing according to their intrinsic mechanisms and in social systems responding to internal and external pressures. Systems are parts of hierarchies where systems of higher levels are made up of subsystems from lower levels. Renewal in components is an important factor of adaptation and evolution. If a system is sustained for too long, it borrows from the sustainability of a supersystem and rests upon lack of sustainability in subsystems. Therefore by sustaining certain systems beyond their renewal cycle, we decrease the sustainability of larger, higher-level systems. For example, Schumpeter's theory of creative destruction posits that in a capitalist economy, the collapse and renewal of firms and industries is necessary to sustain the vitality of the larger economic system. However, if the capitalist economic system relies on endless growth, then sustaining it for too long will inevitably borrow from the sustainability of the global ecosystem. This could prove catastrophic for humans and other species. To reconcile sustainability with hierarchy theory, we must decide which hierarchical level in a system we want to sustain indefinitely, and accept that lower level subsystems must have shorter life spans. In economic analysis, inter-temporal discount rates essentially tell us how long we should care about sustaining any given system. Economists distinguish between discount rates for individuals based on personal time preference, lower discount rates for firms based on the opportunity cost of capital, and even lower discount rates for society. For issues affecting even higher-level systems, such as global climate change, many economists question the suitability of discounting future values at all. We argue that to reconcile sustainability with inter-temporal discounting, discount rates should be determined by the hierarchical level of the system being analyzed.     

The role of accounting in supporting adaptation to climate change

The study is one of the first concerned with the topic of accounting and climate change adaptation. It proposes that the accounting role can support organisational climate change adaptation by performing the following functions: (i) a risk assessment function (assessing vulnerability and adaptive capacity), (ii) a valuation function (valuing adaptation costs and benefits) and (iii) a disclosure function (disclosure of risk associated with climate change impacts). This study synthesises and expands on existing research and practice in environmental accounting and sets the scene for future research and practice in the emerging area of accounting for climate risk.