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The presence of satellite cities within large metropolitan areas cannot be captured by an exponential function. Cubic spline functions seem more appropriate to depict the polycentric pattern of modern urban systems. Using data from the Barcelona Metropolitan Region, two possible population satellite city delimitation procedures using cubic spline density functions are discussed: one, taking an estimated derivative equal to zero; the other, a density gradient equal to zero. It is argued that a delimitation strategy based on derivatives is more appropriate than one based on gradients because the estimated density can be negative in sections with very low densities and few observations, leading to sudden changes in estimated gradients. It is also argued that delimiting satellite cities using a second derivative with a zero value permits the capture of a more restricted area than using a first derivative zero. This methodology can also be used for intermediate ring delimitation.

This paper identifies conditions under which, starting from any tax distorting equilibrium, destination- and origin-based indirect tax-harmonizing reforms are potentially Pareto improving in the presence of global public goods. The first condition (unrequited transfers between governments) requires that transfers are designed in such a way that the marginal valuations of the global public goods are equalized, whereas the second (conditional revenue changes) requires that the change in global tax revenues, as a consequence of tax harmonization, is consistent with the direction of inefficiency in global public good provision relative to the (modified) Samuelson rule. Under these conditions, tax harmonization results in redistributing the gains from a reduction in global deadweight loss and any changes in global tax revenues according to the Pareto principle. And this is the case independently of the tax principle in place (destination or origin).

This paper presents a new method for edge-preserving color image denoising based on the tensor voting framework, a robust perceptual grouping technique used to extract salient information from noisy data. The tensor voting framework is adapted to encode color information through tensors in order to propagate them in a neighborhood by using a specific voting process. This voting process is specifically designed for edge-preserving color image denoising by taking into account perceptual color differences, region uniformity and edginess according to a set of intuitive perceptual criteria. Perceptual color differences are estimated by means of an optimized version of the CIEDE2000 formula, while uniformity and edginess are estimated by means of saliency maps obtained from the tensor voting process. Measurements of removed noise, edge preservation and undesirable introduced artifacts, additionally to visual inspection, show that the proposed method has a better performance than the state-of-the-art image denoising algorithms for images contaminated with CCD camera noise. ; Funding Agencies|Spanish Ministry of Science and Technology|DPI2007-66556-C03-03|Department of Innovation, Universities and Companies of the Catalonian Government||European Social Fund||

The European energy sector is undergoing a major transformation and is facing a series of difficult challenges. These include a high and increasing dependence on external energy resources; dramatically reduce the need for the emissions of greenhouse gases to meet environmental objectives and the difficulties related to the promotion of energy market effectively integrated and competitive. Some of the policies associated with the various objectives are sometimes in conflict with each other, while in other cases are mutually reinforcing.The aim of this paper is to do a scienti?c analysis of the developments so far and the expectations for the coming period focusing on the pillars of energy policy in the EU in terms of security of supply, environment, climate change and promoting a competitive and integrated market. The use of renewable energy sources is seen as a key element of European energy policy and should help to: reduce dependence on fuel from non-member countries; reduce emissions from carbon-based energy sources, and; decouple energy costs from oil prices.