The optimal provision of public inputs in a second best scenario

This paper provides a simple general equilibrium model with productive public spending and distorting taxes. The optimal conditions for the provision of public inputs are obtained under different tax systems. Also we discuss which factors affect the marginal cost of public funds.

How does a fisacl reform affect elasticities of income tax revenues? the case os Spain, 2003-2008

This paper estimates the extent to which an exogenous change in income affects income tax revenues. We focus on the case of Spain over the period 2003-2008, as income tax there underwent a substantial reform in 2007. Using both an analytical method and a numerical simulation, we find a significant increase in aggregate income tax elasticities from 1.4 for 2003-2003 to around 1.8 for 2007-2008. The sensitivity of results to the presence of housing tax credits, non-equiproportional variations in income, changes in income inequality and fiscal drag is also considered.income tax elasticity; progressivity; tax rates; tax credits

Measurement-based Protocol Design

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Flow-induced pruning of branched systems and brittle reconfiguration

Whereas most plants are flexible structures that undergo large deformations under flow, another process can occur when the plant is broken by heavy fluid-loading. We investigate here the mechanism of such possible breakage, focusing on the flow-induced pruning that can be observed in plants or aquatic vegetation when parts of the structure break under flow. By computation on an actual tree geometry, a 20-yr-old walnut tree (Juglans Regia L.) and comparison with simple models, we analyze the influence of geometrical and physical parameters on the occurrence of branch breakage and on the successive breaking events occurring in a tree-like structure when the flow velocity is increased. We show that both the branching pattern and the slenderness exponent, defining the branch taper, play a major role in the breakage scenario. We identify a criterion for branch breakage to occur before breakage of the trunk. In that case, we show that the successive breakage of peripheral branches allows the plant to sustain higher flow forces. This mechanism is therefore similar to elastic reconfiguration, and can be seen as a second strategy to overcome critical events, possibly a widespread solution in plants and benthic organisms.Comment: 9 pages, 9 figure

Diverging fluctuations of the Lyapunov exponents

D. P. acknowledges support by MINECO (Spain) under a Ramón y Cajal fellowship. We acknowledge support by MINECO (Spain) under Project No. FIS2014-59462-P.Peer reviewedPublisher PD

A space-averaged model of branched structures

Many biological systems and artificial structures are ramified, and present a high geometric complexity. In this work, we propose a space-averaged model of branched systems for conservation laws. From a one-dimensional description of the system, we show that the space-averaged problem is also one-dimensional, represented by characteristic curves, defined as streamlines of the space-averaged branch directions. The geometric complexity is then captured firstly by the characteristic curves, and secondly by an additional forcing term in the equations. This model is then applied to mass balance in a pipe network and momentum balance in a tree under wind loading.Comment: 10 pages, 11 figure

Maîtrise des risques dans le processus de réponse à appel d’offres

Un appel d'offres (AO) permet à un client d’émettre une demande de travaux ou de services envers des prestataires potentiels et de faire ensuite, par analyse des réponses reçues, le choix de celui qui sera retenu. Du point de vue du soumissionnaire, il existe plusieurs risques au moment de répondre car il doit élaborer une réponse sur un développement futur. De nature différente, ces risques peuvent être regroupés en catégories. Nous proposons une typologie des risques sur laquelle nous nous appuyons afin d'assister le prestataire lors du processus de réponse à appel d’offre (PRAO) via une méthodologie d'aide à la décision fondée sur l’expérience acquise dans le déroulement des projets passés pour détecter, rendre compte et minimiser les risques du PRAO en cours

On the optimal level of public inputs.

This paper studies the optimal level of public inputs under two different tax settings. With this aim, we adapt the approach by Gronberg and Liu (2001) to the case of productivity-enhancing public spending. We find that it is not analytically clear whether the first-best level of public spending exceeds the second-best level. After taking account the type of public input, a wide numerical simulation has been carried out. We obtain that the second-best level is always below the first-best level but the criterion by Gronberg and Liu has to be qualified.Second best, excess burden, public input.