Accounting for Uncertainty Affecting Technical Change in an Economic-Climate Model

The key role of technological change in the decline of energy and carbon intensities of aggregate economic activities is widely recognized. This has focused attention on the issue of developing endogenous models for the evolution of technological change. With a few exceptions this is done using a deterministic framework, even though technological change is a dynamic process which is uncertain by nature. Indeed, the two main vectors through which technological change may be conceptualized, learning through R&D investments and learning-by-doing, both evolve and cumulate in a stochastic manner. How misleading are climate strategies designed without accounting for such uncertainty? The main idea underlying the present piece of research is to assess and discuss the effect of endogenizing this uncertainty on optimal R&D investment trajectories and carbon emission abatement strategies. In order to do so, we use an implicit stochastic programming version of the FEEM-RICE model, first described in Bosetti, Carraro and Galeotti, (2005). The comparative advantage of taking a stochastic programming approach is estimated using as benchmarks the expected-value approach and the worst-case scenario approach. It appears that, accounting for uncertainty and irreversibility would affect both the optimal level of investment in R&D –which should be higher– and emission reductions –which should be contained in the early periods. Indeed, waiting and investing in R&D appears to be the most cost-effective hedging strategy.Stochastic Programming, Uncertainty and Learning, Endogenous Technical Change

Cibles des médicaments antithrombotiques

Pour la quasi-totalité des classes thérapeutiques antithrombotiques actuellement utilisées et à venir, le ciblage a été initialement la conséquence d’une observation et non pas le fruit d’une recherche méthodique scientifique. Une fois la preuve de l’efficacité démontrée, le but du développement pharmaceutique a été de découvrir des familles moléculaires qui améliorent l’efficacité et les relations cinétique/dynamique. Les rares cas de développement d’une stratégie contre une cible spécifique, identifiée à partir des connaissances des mécanismes fondamentaux de la thrombogenèse, n’ont pas été des succès. La nature paraît avoir déjà exploité toutes les cibles efficaces et il semble qu’il n’est possible que de la copier en essayant de l’améliorer par quelques détails pharmacocinétiques ou galéniques attractifs. Quoiqu’il en soit, le développement de nombreuses formes moléculaires dirigées contre plusieurs cibles a lieu et la mise à disposition de molécules spécifiques des différentes cibles devrait modifier notre prise en charge des états thrombotiques chez les patients : nous allons passer d’une ère où nous cherchions à utiliser au mieux les rares thérapeutiques dont nous disposions à une ère où nous aurons à déterminer, pour chaque situation thrombotique, la meilleure cible à inhiber et le meilleur degré d’inhibition à atteindre.New antithrombotic agents are being developed not only to improve efficacy, but also to increase safety in comparison with widely used conventional agents such as the oral anticoagulants. New anticoagulant, antiplatelet, and profibrinolytic compounds are currently under study in drug development programs, and most of those in phase II or III of development are derived from the observation of natural phenomena and merely mimic processes developed by mammalians, including humans, to avoid thrombosis, or by blood-sucking insects or animals to prevent coagulation of the blood their are feeding on. By contrast, drug candidates identified by means of rigorous research and designed to target new pathways and achieve direct and specific inhibition of factors that are presumed to play an important role in thrombogenesis have generally failed to show any benefit and sometimes even induce deleterious effects. The clinical development of new drugs, even those mimicking natural phenomena, improves our knowledge of the pathogenesis of thrombosis and sheds light, retrospectively, on previous conceptual errors. The improvement in our basic knowledge and the development of new types of drugs suggest that, in contrast to the current antithrombotic compounds that are used in a broad range of clinical settings, use of new drugs should be restricted to specific situations in which their mechanisms of action are predicted to deliver the highest medical benefit. A major obstacle resides in the fact that current drug development programs are still required to comply with long obsolete guidelines based on the characteristics of first-generation antithrombotic agents, and that do not take into account the specific mechanisms of action of new drugs. This situation should change, however, and new antithrombotic drugs should soon be able to benefit from adapted development programs that will make it possible to determine their optimal risk-benefit ratio

Modélisation Intégrée du Changement Climatique - Contribution de l'optimisation par Oracle

La modélisation intégrée du changement climatique a été introduite il y a une vingtaine d’années pour faire le lien entre les sciences humaines, les sciences de la vie et celles du climat afin de répondre aux questions des décideurs sur le problème du changement climatique. Cette thèse présente la méthode de couplage des dynamiques du climat et de l’économie et reformule de cette façon les problèmes d’optimisation de politiques climatiques. À partir de la méthode d’optimisation par oracle et l’algorithme Proximal-ACCPM, on répertorie les problèmes apparaissant lorsque l’oracle renvoit une information approximative, puis on présente des solutions mises en place pour y remédier. Dans une seconde partie, on présente la mise en œuvre des différents couplages : une première illustration empirique de la méthode, la décomposition des dynamiques de l’économie et du climat du modèle DICE et enfin, en représentant le climat par un modèle de circulation générale decomplexité intermédiaire C-GOLDSTEIN, on expose différents couplages entre la partie économique du MEI MERGE et les deux modèles C-GOLDSTEIN et CBM-GOLDSTEIN

An oracle based method to compute a coupled equilibrium in a model of international climate policy

This paper proposes a computational game-theoretic model for the international negotiations that should take place at the end of the period covered by the Kyoto protocol. These negotiations could lead to a self-enforcing agreement on a burden sharing scheme given the necessary global emissions limit that will be imposed when the real extent of climate change is known. The model assumes a non-cooperative behavior of the parties except for the fact that they will be collectively committed to reach a target on total cumulative emissions by the year 2050. The concept of normalized equilibrium, introduced by J.B. Rosen for concave games with coupled constraints, is used to characterize a family of dynamic equilibrium solutions in an m-player game where the agents are (groups of) countries and the payoffs are the welfare gains obtained from a Computable General Equilibrium (CGE) model. The model deals with the uncertainty about climate sensitivity by computing an S-adapted equilibrium. These equilibria are computed using an oracle-based method permitting an implicit definition of the payoffs to the different players, obtained through simulations performed with the global CGE model GEMINI-E

Integrated Assessment of Swiss GHG Mitigation Policies After 2012: Coupling the Residential Sector

The residential sector presents a great potential for greenhouse gases (GHG) mitigation. We perform an integrated assessment of different mitigation policies for Switzerland focusing on the residential sector. We analyze the case of pure incentive taxes and technical regulations. For our analysis, we have coupled a general equilibrium model with a Swiss residential energy model. We find that a progressive GHG tax of more than 200 USD2000/tCO2eq is necessary to reach a target of 50% reduction of GHG emissions in 2050. Finally, we also find that efficiency-based technical regulations provide limited additional abatement incentive

Bovine neonate natural killer cells are fully functional and highly responsive to interleukin-15 and to NKp46 receptor stimulation

Natural killer (NK) cells are key components of the innate immune system with their killing and cytokine producing abilities. Bovine NK cells have been characterized as NKp46+/CD3− lymphocytes, but little is known about these cells in neonatal calves. As the newborn calf, with an insufficiently developed acquired immunity, has to employ the innate immune system, we wanted to investigate whether neonate NK cells had the same characteristics as cells from older calves. Freshly isolated neonate and calf NK cells presented the same resting CD2+/CD25low/CD8−/low phenotype. Neonates less than 8 days old had one third of the circulating NKp46+ cells of older calves, but the NK cells proliferated more actively in vitro in the presence of interleukin (IL)-2 or IL-15. Moreover, neonate NK cells were more cytotoxic both in an NKp46 mediated redirected lysis assay and in direct killing of a bovine cell line MDBK when cultured in the presence of IL-15. Neonate and calf NK cells cultured in the presence of IL-2 and then stimulated with IL-12 produced similar dose-dependent interferon (IFN)-γ amounts, while IL-15 cultured NK cells did not give such a response whatever the age. However, neonatal NK cells cultured in IL-15 and stimulated by IL-12 concomitantly with cross-linking of NKp46, produced 4 to 5 times more IFN-γ than calf NK cells. These data suggest that although present in lower number at birth, neonate NK cells are fully functional and are more responsive to IL-15 and activation through the NKp46 receptor than NK cells from older calves

Transformation of the 2001 Swiss SAM from ETH Zürich to GEMINI-E3 format

This paper describes the methodology used to transform the 2001 Swiss SAM devised at ETH Zürich and align it to the requirements of the GEMINI-E3 model which is based on the GTAP database

An Oracle method to couple climate and economic dynamics

This paper deals with an oracle method to couple economic and climate models. The approach permits a dialogue between two models pertaining to two different scientific domains, the climate module being a fully-coupled ocean-atmosphere-ice model, whereas the economic module is an adaptation of the neo-classical optimal economic growth paradigm. The paper explains how the Analytic Centre Cutting Plane Method (ACCPM) is implemented to integrate in the optimal economic growth model a constraint on climate change that is computed from the climate model runs. Several experiments show the usefulness of the approach to build new types of integrated assessment meta-model

The feasibility of a world-wide tax on anthropogenic emissions of greenhouse gases: Levels and impacts of world-wide taxes on greenhouse gases

A harmonized worldwide carbon tax, implemented at regional or national level, can be enforced only with an international collective action which takes into account inherent interests of all countries. The purpose of this study is to assess the impact ofthe implementation of such a tax by means of different scenarios based on realistic assumptions. We endeavor to design a world tax on anthropogenic greenhouse-gases emissions which can be politically acceptable and technically feasible. To do so, we also address international equity through lump-sum transfer and transfers based on countries’ financial capacity. Part of the Report 'The Feasibility of a World-wide Tax on Anthropogenic Emissions of Greenhouse Gases' for the Federal Office of the Environmen

Contrefactuels en histoire : du mot au mode d’emploi. Le moment de la new economic history

L’approche contrefactuelle désigne, pour les historiens, une forme particulière que peut prendre le récit historique ou la pratique de l’histoire. Raisonner contrefactuellement, dans ce cadre, c’est se demander ce qui se serait passé si la réalité avait été différente. Le plus souvent, il s’agit de supprimer en pensée un événement ou une réalité historique et de s’interroger sur les conséquences de cette suppression. Que se serait-il passé si Hitler était mort pendant la Première Guerre mondi..