Spatial interactions in agent-based modeling

Agent Based Modeling (ABM) has become a widespread approach to model complex interactions. In this chapter after briefly summarizing some features of ABM the different approaches in modeling spatial interactions are discussed. It is stressed that agents can interact either indirectly through a shared environment and/or directly with each other. In such an approach, higher-order variables such as commodity prices, population dynamics or even institutions, are not exogenously specified but instead are seen as the results of interactions. It is highlighted in the chapter that the understanding of patterns emerging from such spatial interaction between agents is a key problem as much as their description through analytical or simulation means. The chapter reviews different approaches for modeling agents' behavior, taking into account either explicit spatial (lattice based) structures or networks. Some emphasis is placed on recent ABM as applied to the description of the dynamics of the geographical distribution of economic activities, - out of equilibrium. The Eurace@Unibi Model, an agent-based macroeconomic model with spatial structure, is used to illustrate the potential of such an approach for spatial policy analysis.Comment: 26 pages, 5 figures, 105 references; a chapter prepared for the book "Complexity and Geographical Economics - Topics and Tools", P. Commendatore, S.S. Kayam and I. Kubin, Eds. (Springer, in press, 2014

Relationship Between Anti-DFS70 Autoantibodies and Oxidative Stress

Background: The anti-DFS70 autoantibodies are one of the most commonly and widely described agent of unknown clinical significance, frequently detected in healthy individuals. It is not known whether the DFS70 autoantibodies are protective or pathogenic. One of the factors suspected of inducing the formation of anti-DFS70 antibodies is increased oxidative stress. We evaluated the coexistence of anti-DFS70 antibodies with selected markers of oxidative stress and investigated whether these antibodies could be considered as indirect markers of oxidative stress. Methods: The intensity of oxidative stress was measured in all samples via indices of free-radical damage to lipids and proteins such as total oxidant status (TOS), concentrations of lipid hydroperoxides (LPH), lipofuscin (LPS), and malondialdehyde (MDA). The parameters of the non-enzymatic antioxidant system, such as total antioxidant status (TAS) and uric acid concentration (UA), were also measured, as well as the activity of superoxide dismutase (SOD). Based on TOS and TAS values, the oxidative stress index (OSI) was calculated. All samples were also tested with indirect immunofluorescence assay (IFA) and 357 samples were selected for direct monospecific anti DFS70 enzyme-linked immunosorbent assay (ELISA) testing. Results: The anti-DFS70 antibodies were confirmed by ELISA test in 21.29% of samples. Compared with anti-DFS70 negative samples we observed 23% lower concentration of LPH (P =.038) and 11% lower concentration of UA (P =.005). TOS was 20% lower (P =.014). The activity of SOD was up to 5% higher (P =.037). The Pearson correlation showed weak negative correlation for LPH, UA, and TOS and a weak positive correlation for SOD activity. Conclusion: In samples positive for the anti-DFS70 antibody a decreased level of oxidative stress was observed, especially in the case of samples with a high antibody titer. Anti-DFS70 antibodies can be considered as an indirect marker of reduced oxidative stress or a marker indicating the recent intensification of antioxidant processes

Emissions Trading, CDM, JI, and More - The Climate Strategy of the EU

The objective of this paper is to assess the likely allocation effects of the current cli-mate protection strategy as it is laid out in the National Allocation Plans (NAPs) for the European Emissions Trading Scheme (ETS). The multi-regional, multi-sectoral CGE-model DART is used to simulate the effects of the current policies in the year 2012 when the Kyoto targets need to be met. Different scenarios are simulated in or-der to highlight the effects of the grandfathering of permits to energy-intensive instal-lations, the use of the project-based mechanisms (CDM and JI), and the restriction imposed by the supplementarity criterion

Accounting for Extreme Events in the Economic Assessment of Climate Change

Extreme events are one of the main channels through which climate and socio- economic systems interact. It is likely that climate change will modify their probability distributions and their consequences. The long-term growth models used in climate change assessments, however, cannot capture the effects of short-term shocks; they thus model extreme events in a very crude manner. To assess the importance of this limitation, a non-equilibrium dynamic model (NEDyM) is used to model the macroeconomic consequences of extreme events. Its conclusions are the following: (i) Dynamic processes multiply the extreme event direct costs by a factor 20; half of this increase comes from short-term processes; (ii) A possible modication of the extreme event distribution due to climate change can be responsible for significant GDP losses; (iii) The production losses caused by extreme events depend, with strong non-linearity, both on the changes in the extreme distribution and on the ability to fund the rehabilitation after each disaster. These conclusions illustrate that the economic assessment of climate change does not only depend on beliefs on climate change but also on beliefs on the economy. Moreover, they suggest that averaging short-term processes like extreme events over the five- or ten-year time step of a classical long-term growth model can lead to inaccurately low assessments of the climate change damages

Asymmetric Labor Markets, Southern Wages, and the Location of Firms

This paper studies the behavior of firms towards weak labor rights in developing countries (South). A less than perfectly elastic labor supply in the South gives firms oligopsonistic power tempting them to strategically reduce output to cut wages. In an open economy, competitors operating in perfectly competitive labor markets meanwhile enjoy less aggressive competitors and raise output. Finally, competition effect reduces the ex-post output of a relocating firm. These effects reduce relative profitability of the South casting doubts on traditional beliefs that multinationals are attracted to regions with lower wages. Adopting a minimum wage unambiguously enhances Southern competitiveness and welfare

Protection Motivation Theory and Contingent Valuation: Perceived Realism, Threat and WTP Estimates for Biodiversity Protection

We report on a discrete-choice CV study conducted in Germany to value the WTP for biodiversity protection in less developed countries. To systematically investigate survey realism and subjective threat assessment from the loss of biodiversity described in the scenario the study includes questions to uncover the constructs of Protection Motivation Theory, which is introduced to the CV literature. The patterns of responses to such questions are analysed using an Expectation-Maximization algorithm to derive class membership probabilities. These are found to match the predictions of Protection Motivation Theory and systematically improve the logistic analysis of the WTP responses

Environmental Resources Depletion and Interplay Between Negative and Positive Externalities in a Growth Model

We analyse growth dynamics in an economy where the well-being of economic agents depends on three goods: leisure, a free access environmental good and a private good which can be produced by each agent through his own labour input. The private good can be consumed as a substitute for the environmental resource. The production process of the private good by each agent generates negative externalities on the other agents, by depleting the free access natural resource; but it also produces positive externalities by increasing the productivity of labour via a learning-by-doing mechanism of accumulation of knowledge [which is a pure public good]. In this context, we show that attracting steady states may exist which are Pareto-dominated by others where aggregate private consumption and labour productivity are lower. However, negative externalities can also be an engine of desirable growth: the deterioration of the environmental good can play the role of a coordination device leading economic agents to a wider exploitation of positive externalities

Estimating the New Keynesian Phillips Curve for Italian Manufacturing Sectors

The purpose of this paper is to test the general validity of the NKPC previsions for the Italian manufacturing industries. In particular we are interested in estimating the extent to which the degree of nominal inertia and the fraction of backward-looking price-setters differ from industry to industry. We attempt to address this issue by testing three different model specifications: a pure forward-looking model versus a hybrid model where an income labour share marginal cost measure is considered, and a modified hybrid model specification where marginal costs are corrected to include intermediate inputs. Our results show that the backward-looking component is statistically significant and quantitatively large for all industries. Moreover, this estimate does not depend on the models specification. Conversely, the parameter measuring the extent of price rigidity is sensitive to the definition of firms cost. Interpreting the overall results, we conclude that price-setting behaviour is not totally homogeneous among Italian firms