Renegotiation of Concession Contracts in Latin America.

We construct a regulation model in which renegotiation occurs due to the imperfect enforcement of concession contracts. This enables us to provide theoretical predictions for the impact, on the probability of renegotiation of a concession, of regulatory institutions, institutional features, economic shocks and of the characteristics of the concession contracts themselves. Then we use a data set of nearly 1000 concessions awarded in Latin America and the Caribbean countries from 1989 to 2000, covering the sectors of telecommunications, energy, transport and water, to test these predictions. Finally, we derive some policy implications of our theoretical and empirical work.Renegotiation, Concession contracts, Regulation, LDCs.

Infrastructure concessions in Latin America : government-led renegotiations

The authors complement the existing knowledge in the renegotiation literature on infrastructure concessions by analyzing government-led renegotiations. They first propose a multiple-period theoretical framework in which both Pareto-improving and rent-shifting renegotiations at the initiative of the government can occur. They then perform an empirical analysis based on a sample of 307 water and transport projects in five Latin American countries between 1989 and 2000. While some of the main insights from the previous literature are unchanged, for example concerning the importance of having a regulator in place when awarding concessions and the fragility of price cap regulatory schemes, there are also significant differences as predicted by the model, in particular with respect to the effect of investment and financing, as well as the corruption variables. The authors provide additional evidence showing that a good regulatory framework is especially important in contexts with weak governance and political opportunism.

Concessions of Infrastructure in Latin America: Government-led Renegotiation

This paper completes Guasch, Laffont and Straub (2003), extending the analysis to the case of government-led renegotiations. We first extend the theoretical framework to a multiple-period context in which both Pareto improving and rent shifting renegotiations at the initiative of the government can occur. We then perform an empirical analysis based on the same sample of 307 water and transport projects in 5 Latin American countries between 1989 and 2000. While some of the main insights, for example concerning the importance of having a regulator in place when awarding concessions and the fragility of price cap regulatory schemes, are unchanged, there are also significant differences, in particular with respect to the effect of investment and financing, as well as the corruption variables. We also provide additional evidence showing that a good regulatory framework is especially important in contexts with weak governance and political opportunism.

Renegotiation of concession contracts in Latin America

The authors construct a regulation model in which renegotiation occurs due to the imperfect enforcement of concession contracts. This enables the authors to provide theoretical predictions for the impact on the probability of renegotiation of a concession, regulatory institutions, institutional features, economic shocks, and the characteristics of the concession contracts. Then they use a data set of nearly 1,000 concessions awarded in Latin America and the Caribbean countries from 1989 to 2000 covering the sectors of telecommunications, energy, transport, and water to test these predictions. Finally, the authors derive some policy implications of their theoretical and empirical work.Environmental Economics&Policies,Health Economics&Finance,Administrative&Regulatory Law,Decentralization,Labor Policies,Health Economics&Finance,Environmental Economics&Policies,National Governance,Administrative&Regulatory Law,Public Sector Economics&Finance

Nanotexture influence of BaTiO3 particles on piezoelectric behaviour of PA 11/BaTiO3 nanocomposites

The piezoelectric activity of a hybrid ferroelectric nanocomposite, i.e. polyamide 11/barium titanate (BT), has been investigated for different loadings of BT particles. The BT volume fraction (/) was ranging from 0.024 to 0.4 with a particle size of 50, 100, 300 and 700 nm. The influence of polarization mode on the piezoelectric behaviour has been studied. The magnitude of the poling field used in this study is in the same order of magnitude of the one used for bulk BT i.e. significantly lower than for piezoelectric polymers. The optimum piezoelectric coefficient is reached when the amorphous phase of the polymeric matrix is in the liquid state i.e. for a polarization temperature higher than the glass transition and for time constant allowing macromolecular mobility. The composite piezoelectric activity decreases for particles size lower than 300 nm due to the loss of the tetragonal phase. The nanotexture of these particles has been investigated by transmission electron microscopy (TEM) and high-resolution TEM. A core shell structure has been observed. An increase of the longitudinal piezoelectric strain coefficient d33 with the raising of BT volume fraction was shown. Contrary to inorganic piezoelectric ceramics, the dielectric permittivity of hybrid composites remains moderate; therefore it allows the piezoelectric voltage coefficient of composites to be higher than ceramics

Beyond stroke: Impact of the lesion side on the recovery of between-hands coordination

ObjectiveOne-fit-all post-stroke rehabilitation has limited plausibility. Better understanding the effects of the lesion location on the recovery process may help to develop new tailored therapeutic strategies to individuals. The purpose of this study was to assess the natural evolution of bimanual coordination over standard rehabilitation according to the lesion side, aiming to identify a potential responder-profile for bimanual-oriented therapy.Material/patientsTwelve hemiparetic, moderately impaired patients were included within 30 days after a first unilateral stroke. The kinematic and clinical assessments were performed once a week for 6 weeks and at 3 months after inclusion. The patients performed a reach-to-grasp task in unimanual condition followed by a synchronous bimanual condition. The clinical evaluation included the Fugl-Meyer Assessment, Box and Block Test, 9-Hole Peg Test and Barthel Index.ResultsThe clinical scores indicated no difference in motor function between left- (LHD) and right-hemispheric damaged (RHD) patients over time. Interestingly, the LHD patients produced smoother bimanual reaching movements than the RHD patients while we found no effect of the lesion side on reaching kinematics of the paretic UL in unimanual condition. These inter-group differences disappeared after 5 weeks of standard therapy, likely indicating a time lag in motor recovery.DiscussionBecause the RHD patients were less prematurely coordinated again during bimanual movements than the LHD patients, they may benefit differently from a bimanual rehabilitation, and especially from the simultaneous involvement of the ipsilesional UL. It becomes necessary to investigate to what extent this difference due to lesion side may be integrated into the design of rehabilitation protocols

Opting out and topping up reconsidered: Informal care under uncertain altruism

National audienceWe study the design of public long-term care (LTC) insurance when the altruism of informal caregivers is uncertain. We consider non-linear policies where the LTC transfer depends on the level of informal care, which is assumed to be observable, while children's altruism is not. Our policy encompasses two policies traditionally considered in the literature: topping up policies consisting of a transfer independent of informal care, and opting out policies entailing a positive transfer only if children fail to provide care. We show that both total and informal care should increase with the children's level of altruism. This is obtained under full and asymmetric information. Public LTC transfers, on the other hand, may be non-monotonic. Under asymmetric information, public LTC transfers are lower than their full information level for the parents whose children are the least altruistic, while it is distorted upward for the highest level of altruism. This is explained by the need to provide incentives to highly altruistic children. In contrast to both topping up and opting out policies, the implementing contract is always such that social care increases with informal care.Repenser les polices exclusives et non-exclusives : les soins informels dans un contexte de devouement aleatoire. Dans cet article, nous etudions le modele public d'assurance de soins de longue duree lorsque le devouement des aidants naturels est aleatoire. Nous nous interessons aux polices non-lineaires ou le transfert des soins de longue duree depend du niveau de soins informels, lequel etant supposement observable, a l'inverse du devouement des enfants, qui ne l'est pas. Notre police s'appuie sur les deux polices traditionnellement etudiees dans la litterature : les polices non-exclusives ( topping up policies ) consistant en un transfert independant des soins informels, et les polices exclusives ( opting out policies ) impliquant un transfert positif uniquement lorsque les enfants sont dans l'incapacite de fournir de l'aide. Nous montrons que l'ensemble des soins ainsi que les soins informels devraient augmenter proportionnellement au devouement des enfants, que l'information soit complete ou asymetrique. Les transferts publics de soins de longue duree, en revanche, peuvent s'averer non monotones. Dans un contexte d'information asymetrique, et pour les parents dont les enfants sont les moins devoues, les transferts publics de soins de longue duree sont inferieurs a ceux observes dans un contexte d'information complete; pour les parents dont les enfants sont les plus devoues, on observe une distorsion a la hausse. Ceci s'explique par la necessite de fournir des mesures incitatives aux enfants hautement devoues. Et contrairement aux polices exclusives et non-exclusives, le contrat d'execution est toujours tel que les soins sociaux augmentent proportionnellement aux soins informels

Efficiency Guarantees in Auctions with Budgets

In settings where players have a limited access to liquidity, represented in the form of budget constraints, efficiency maximization has proven to be a challenging goal. In particular, the social welfare cannot be approximated by a better factor then the number of players. Therefore, the literature has mainly resorted to Pareto-efficiency as a way to achieve efficiency in such settings. While successful in some important scenarios, in many settings it is known that either exactly one incentive-compatible auction that always outputs a Pareto-efficient solution, or that no truthful mechanism can always guarantee a Pareto-efficient outcome. Traditionally, impossibility results can be avoided by considering approximations. However, Pareto-efficiency is a binary property (is either satisfied or not), which does not allow for approximations. In this paper we propose a new notion of efficiency, called \emph{liquid welfare}. This is the maximum amount of revenue an omniscient seller would be able to extract from a certain instance. We explain the intuition behind this objective function and show that it can be 2-approximated by two different auctions. Moreover, we show that no truthful algorithm can guarantee an approximation factor better than 4/3 with respect to the liquid welfare, and provide a truthful auction that attains this bound in a special case. Importantly, the liquid welfare benchmark also overcomes impossibilities for some settings. While it is impossible to design Pareto-efficient auctions for multi-unit auctions where players have decreasing marginal values, we give a deterministic $O(\log n)$-approximation for the liquid welfare in this setting

Public Good Overprovision by a Manipulative Provider

We study contracting between a public good provider and users with private valuations of the good. We show that, once the provider extracts the users' private information, she benefits from manipulating the collective information received from all users when communicating with them. We derive conditions under which such manipulation determines the direction of distortions in public good provision. If the provider is non-manipulative, the public good is always underprovided, whereas overprovision occurs with a manipulative provider. With overprovision, not only high-valuation users, but also low-valuation users may obtain positive rents—users may prefer facing a manipulative provider.Peer Reviewe