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Urban regions are important places of ecosystem service demands and, at the same time, are the primary source of global environmental impacts. Although there is broad agreement on the importance of incorporating the concept of ecosystem services into policy strategies and decision-making, the lack of a standardized approach to quantifying ecosystem services at the landscape scale has hindered progress in this direction. Moreover, tradeoffs between ecosystem services and the supply/demand ratio of ecosystem services in urban landscapes have rarely been investigated. In our paper, we present a method to quantify and map the supply and demand of three essential provisioning services - energy, food, and water - along the rural-urban gradient of the eastern German region Leipzig-Halle. This urban region has experienced significant socio-economic dynamics and land use changes since the German reunification in 1990. The results show that both the demand and the supply of ecosystem services changed considerably during the time span under consideration (1990-2007). We identified an increasing supply/demand ratio of food and water but a decreasing supply/demand ratio of energy. In addition, the pattern of ecosystem demands shows a levelling of rural-urban gradients, reflecting profound modifications of traditional rural-urban relationships. The changes of ecosystem service supply gradients are determined more by land use intensity, such as the intensification of agricultural production, than by land cover changes such as urban sprawl. The comparison of supply/demand ratios and rural-urban patterns of ecosystem services can help decision-makers in landscape management in striving for a sustainable balance between resource supply and demand.  相似文献   
53.
Rational expectations are often used as an argument against policy activism, as they may undermine or neutralize the policymaker’s actions. Although this sometimes happens, rational expectations do not always imply policy invariance or ineffectiveness. In fact, in certain circumstances rational expectations can enhance our power to control an economy over time. In those cases, policy announcements can be used to extend the impact of conventional policy instruments. We present a general forward-looking policy framework and use it to provide a formal rationale for testing when policymakers can and cannot expect to be able to manage expectations. To describe the relevance of our results applications are shown for policy design in small-open economies. Those are the cases where domestic policies are at their weakest and our ability to influence expectations most constrained.  相似文献   
54.
This paper studies the empirically relevant problem of estimation and inference in diffusion index forecasting models with structural instability. Factor model and factor augmented regression both experience a structural change with different unknown break dates. In the factor model, we estimate factors and loadings by principal components. We consider least squares estimation of the factor augmented regression and propose a break test. The empirical application uncovers instabilities in the linkages between bond risk premia and macroeconomic factors.  相似文献   
55.
Review of Quantitative Finance and Accounting - This paper presents a data-driven complex network approach, to show similarities and differences—in terms of financial risks—between the...  相似文献   
56.
This paper analyzes the connection between innovation activities of companies – implemented before crisis – and their performance – measured at time of crisis. The companies listed in the STAR Market Segment of the Italian Stock Exchange are analyzed. Innovation is measured through the level of investments in total tangible and intangible fixed assets in 2006–2007, while performance is captured through growth – expressed by variations of sales, total assets and employees – profitability – through ROI or ROS – and productivity – through asset turnover or sales per employee in the period 2008–2010. The variables of interest are analyzed and compared through statistical techniques and by adopting cluster analysis. In particular, a Voronoi tessellation is also implemented in a varying centroids framework. In accord with a large part of the literature, we find that the behaviour of the performance of the companies is not univocal when they innovate.  相似文献   
57.
The agro‐food sector has experienced a profound transformation of contractual arrangements along the value chain, coinciding with important technological innovations and product quality upgrading. Our understanding of the impact that this transformation has had on trade flows in the agricultural sector is very limited. In particular, we have limited knowledge about the extent to which the patterns in agro‐food trade have been driven by the quality of contractual institutions. Using existing measures which capture the sensitivity of agro‐food products to contractual imperfections, we show that countries with better contract enforcement specialise in the production of food which requires higher level of relationship‐specific investments. We also find that countries with better contracting institutions and producing contract‐intensive goods specialise in exporting high quality foods. In addition, we show that the quality of contracting institutions might importantly affect the process of product quality upgrading.  相似文献   
58.
ABSTRACT

William Nordhaus and Paul Romer shared the 2018 Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel for their work on long-run macroeconomic analysis. Nordhaus adapted the neoclassical growth model to study climate change, while Romer developed a model of innovation-based growth. The authors provide two distinct explanations of what drives growth, and employ contrasting methodologies for interpreting the results of their mathematical models. Macroeconomic policy in general, and climate policy in particular, would benefit from better integrating the theory and methods of these two laureates.  相似文献   
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Consistent with social motivation theory, prior research on managerial motivation suggests that effort is contagious across management team members. In this study, we draw on belongingness theory to develop a model on important boundary conditions to social motivation theory in the management team context. The model predicts that new venture managers react to their teammates’ higher effort levels by investing higher effort levels themselves primarily when they are confronted with a threat – namely, low venture performance and high environmental hostility – but that effort is less contagious when managers face little threat. We test our model with a sample of 103 new venture managers nested in 51 management teams in a longitudinal setting capturing managerial effort over 26 weeks. While we do not find a direct relationship between teammates’ effort and a new venture manager’s subsequent effort, we find support for the crucial role of threat in triggering the contagion of managerial effort. We discuss the contributions of our study for research on management teams, performance feedback, and entrepreneurial effort in new ventures.  相似文献   
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