Consumption Risk-sharing in Social Networks

We build a model of informal risk-sharing among agents organized in a social network. A connection between individuals serves as collateral that can be used to enforce insurance payments. We characterize incentive compatible risk-sharing arrangements for any network structure, and develop two main results. (1) Expansive networks, where every group of agents have a large number of links with the rest of the community relative to the size of the group, facilitate better risk-sharing. In particular, “two-dimensional” village networks organized by geography are sufficiently expansive to allow very good risk-sharing. (2) In second-best arrangements, agents organize in endogenous “risksharing islands” in the network, where shocks are shared fully within but imperfectly across islands. As a result, risk-sharing in second-best arrangements is local: socially closer agents insure each other more. In an application of the model, we explore the spillover effect of development aid on the consumption of non-treated individuals.

The trajectory of regulatory reform in the UK in the wake of the financial crisis

There has been much talk about regulatory reform around the world in the wake of the financial crisis but relatively little action. As a major international financial centre, the UK is very much at the heart of the debate and has a particular interest in the ultimate outcome. The financial crisis has exposed the weaknesses of ‘light touch’ regulation and ‘principles-based’ regulation, which characterised the UK system in the pre-crisis phase. Changes to the institutional structure of regulation recently announced by the new coalition government, combined with changes to regulatory style, are likely to have far-reaching consequences for the practice and intensity of regulation in the UK. This article reviews and assesses recent and proposed regulatory changes and considers the relationship between corporate governance and regulation. It evaluates the impact on the UK system of initiatives undertaken at international and EC levels as well as various interests and incentives within the UK that are likely to be influential in shaping the regulatory regime in years to come

Adjoint string breaking in 4d SU(2) Yang-Mills theory

We compute the static potential of adjoint sources in SU(2) Yang-Mills theory in four dimensions by numerical Monte Carlo simulations. Following a recent calculation in 2+1 dimensions, we employ a variational approach involving string and gluelump operators and obtain clear evidence for string breaking and the saturation of the potential at large distances. For the string breaking scale we find $r_b \approx 1.25{\rm fm}, 2.3 r_0$, or in units of the lightest glueball, $r_b m_{0++} \approx 9.7$. We furthermore resolve the first excitation of the flux-tube and observe its breaking as well. The result for $r_b$ is in remarkable quantitative agreement with the three-dimensional one.Comment: 15 pages, 3 figures; increased statistics; gauge-fixing clarified; typos correcte

A complex network approach to urban growth

The economic geography can be viewed as a large and growing network of interacting activities. This fundamental network structure and the large size of such systems makes complex networks an attractive model for its analysis. In this paper we propose the use of complex networks for geographical modeling and demonstrate how such an application can be combined with a cellular model to produce output that is consistent with large scale regularities such as power laws and fractality. Complex networks can provide a stringent framework for growth dynamic modeling where concepts from e.g. spatial interaction models and multiplicative growth models can be combined with the flexible representation of land and behavior found in cellular automata and agent-based models. In addition, there exists a large body of theory for the analysis of complex networks that have direct applications for urban geographic problems. The intended use of such models is twofold: i) to address the problem of how the empirically observed hierarchical structure of settlements can be explained as a stationary property of a stochastic evolutionary process rather than as equilibrium points in a dynamics, and, ii) to improve the prediction quality of applied urban modeling.evolutionary economics, complex networks, urban growth

The Binary Space Partitioning-Tree Process

The Mondrian process represents an elegant and powerful approach for space partition modelling. However, as it restricts the partitions to be axis-aligned, its modelling flexibility is limited. In this work, we propose a self-consistent Binary Space Partitioning (BSP)-Tree process to generalize the Mondrian process. The BSP-Tree process is an almost surely right continuous Markov jump process that allows uniformly distributed oblique cuts in a two-dimensional convex polygon. The BSP-Tree process can also be extended using a non-uniform probability measure to generate direction differentiated cuts. The process is also self-consistent, maintaining distributional invariance under a restricted subdomain. We use Conditional-Sequential Monte Carlo for inference using the tree structure as the high-dimensional variable. The BSP-Tree process's performance on synthetic data partitioning and relational modelling demonstrates clear inferential improvements over the standard Mondrian process and other related methods

Feedback links between economy-wide and farm-level policies : application to irrigation water management in Morocco

The authors focus on policy interventions for improving irrigation water allocation decisions by including both macro and micro considerations in a unified analytical computable general equilibrium (CGE) framework. The approach is demonstrated, using the case of Morocco, by analyzing selected policy (top-down and bottom-up) interventions and external shocks that affect the water sector. Both direct and indirect effects of these interventions are identified. The top-down (macro-to-micro) links are of a trade reform type. The bottom-up (micro-to-macro) links pertain to changes in farm water assignments and the possibility of water trading. The authors find that water productivity is strongly influenced by these policies, with the general equilibrium (indirect) effects modifying and sometimes reversing the partial equilibrium (direct) effects. They also find that the impacts of the two reforms assessed are different, with trade reform having an absolute impact of a higher magnitude than the water reform. Finally, the authors show that the sequence of introducing the policy reforms has different consequences.Environmental Economics&Policies,Water Supply and Sanitation Governance and Institutions,Town Water Supply and Sanitation,Water Conservation,Water and Industry

Beyond the Border and Back to the Future: Seizing the Opportunity to Enhance Canadian and US Economic Growth and Security

The leaders of Canada and the United States have announced an ambitious vision for perimeter security and economic competitiveness between the two countries. They have charged a working group with producing a multi-year Action Plan that will turn this vision into reality. The vision is centered on the idea that performing inspection and other formalities well before shipments and people arrive at the busy bilateral border will ease costly delays there, and that this can be achieved while simultaneously enhancing security and reducing costs for secure trade and for individuals. The study concludes that these new mechanisms can draw inspiration from existing ones that help provide the mutual trust, dedication and expertise necessary to successfully manage water issues between Canada and the United States.International Economic Policy, trade, Canada, United States, border security