Technical progress in North and welfare gains in South under nonhomothetic preferences

The paper proposes a theoretical model investigating the welfare consequences of technological shocks in a Ricardian framework (a la Dornbush, Fisher and Samuelson, 1977). Contrary to existing literature, the model incorporates a nonhomothetic demand function whose price and income elasticities are endogenously determined by technology. The model is applied to the case of trade between two economies with different development levels. It is shown in particular that the developing country can experience a fall in utility as a result of technical progress in the developed country. This result depends on the type of technological shock assumed (biased vs uniform technical progress), as well as on the size of the development gap.Dornbush-Fisher-Samuelson Ricardian model ; technology and trade ; North-South trade ; nonhomothetic preferences ; hierarchic needs ; hierarchic purchases

Technical progress in North and welfare gains in South under nonhomothetic preferences

The paper proposes a theoretical model investigating the welfare consequences of technological shocks in a Ricardian framework (a la Dornbush, Fisher and Samuelson, 1977). Contrary to existing literature, the model incorporates a nonhomothetic demand function whose price and income elasticities are endogenously determined by technology. The model is applied to the case of trade between two economies with different development levels. It is shown in particular that the developing country can experience a fall in utility as a result of technical progress in the developed country. This result depends on the type of technological shock assumed (biased vs uniform technical progress), as well as on the size of the development gap.Nous proposons un modèle d'inspiration classique (de type Dornbush, Fisher et Samuelson, 1977) qui incorpore une fonction de demande non homothétique et dont les fondements microéconomiques expriment une hiérarchisation des besoins. Contrairement aux modèles de la littérature existante, nous établissons une relation directe entre progrès technique et valeur des élasticités de la demande. Le modèle proposé est appliqué au cas de deux économies de niveaux de développement différents et est utilisé pour analyser l'impact du progrès technique sur le bien-être. Nous montrons que le pays en développement peut connaître une baisse de son utilité suite à un progrès technique dans le pays développé. Cette configuration dépend du type de choc technologique supposé (biaisé vers les biens les plus sophistiqués) et de l'écart de niveau de développement

Institutions, unemployment and inactivity in the OECD countries

This paper provides new evidence on the linkages between a large array of institutional arrangements (on product, labour and financial markets) and employment performance. Our analysis includes unemployment, inactivity and jobless rates, thus allowing us to control for possible substitution effects across situations of non-employment and to check whether institutional rigidities affecting unemployment impact inactivity along the same line. To cope with common problems related to the inclusion of time-invariant institutional variables in fixed effects models, we present results of regressions based on three different estimators: PCSE, GLS and FEVD, the last one being a new procedure specifically designed to treat slowly changing variables. New institutional series are proposed, namely to account for unemployment insurance net replacement rates and employment protection legislation (EPL). Among other results, we find strong evidence of a positive effect of EPL on employment performance as well as of possible complementarities across product and labour markets regulation.unemployment ; inactivity ; institutions ; time-invariant variables

Competition, Innovation and Distance to Frontier

According to a recent literature, the positive effect of competition is supposed to be growing with the proximity to the technological frontier. Using a variety of indicators, the paper tests the effect of competition and regulation on innovative activity measured by patenting. The sample consists of a panel of 15 industries for 17 OECD countries over the period 1979-2003. Results show no evidence of a positive effect of competition growing with the proximity to the frontier. Two main configurations emerge. First, regulation has a positive effect whatever the distance to the frontier and the magnitude of its impact is higher the closer the industry is to the frontier. Second, the effect of regulation is negative far from the frontier and becomes positive (or non significant) when the technology gap decreases. These results contradict the belief in the innovation-boosting effect of product market deregulation such as taken into account in the Lisbon Strategy.Innovation, competition, distance to frontier.

ESA PetriNet: Petri net Based Tool for Reliability Analysis

International audienceThis paper describes the critical (feared) scenarios derivation tool ESA PetriNet (Extraction Scenarios Algorithm from Petri Net) available from : http://www.laas.fr/ESA. ESA PetriNet allows to derive scenarios leading to critical (feared) situation in embedded systems. The system model is given by a Petri net. To derive critical scenarios and to avoid the state space explosion, the solution is to use directly the Petri net model. Linear logic (which does not appears in this paper)offers a theoretical framework to interpret the Petri net model and to extract the scenarios. ESA PetriNet provides all minimal scenarios which contain strictly necessary and sufficient events to reach a specified state. ESA PetriNet can be used with classical Petri net modelling or in its objects oriented version

Stratégie de Lisbonne et Réformes structurelles en Europe

Accessible en ligne : http://www.ires.fr/images/files/Revues/R60-3.pdfInternational audienc

Emotional valence interactions in amygdala circuits

Survival of organisms crucially depends on their ability to adapt their behavior to changes in environmental circumstances. This adaptation to changes in the emotional significance of environmental cues is acquired through two different types of learning: either through conditioning, when animals learn the predictive relationship between environmental cues and biologically relevant outcomes or, through subsequent extinction learning, when the cue is not predictive anymore of the outcome. The amygdala is crucially involved in the learning processes regarding these changes in valence and contingency between stimuli and biologically relevant outcomes. Here we study at the single neuron level the representation and interaction of conditioning and extinction of opposite valences. We show that the basal nucleus of the amygdala encompasses distinct neuronal subpopulations responsible for learning specific changes in stimulus-outcome contingencies in a valence-dependent manner. We first identify basal amygdala neurons specifically responsive to either aversive conditioned cues, the so-called fear neurons, or exclusively to aversive extinguished cues, the fear extinction neurons. Subsequently, the development of a purely Pavlovian appetitive conditioning allowed us to determine that conditioning and extinction are encoded in a very similar manner in the appetitive and aversive domains. We identify appetitive neurons which are cue-responsive after appetitive conditioning and appetitive extinction neurons only responding to appetitive extinguished cues. The identification of these discrete neuronal populations which activity correlates with high and low emotional states raises the question of how conditioning and extinction of opposite valences are represented relative to each other in basal amygdala circuits. We address this question by combining sequential appetitive and aversive learning with chronic single unit recordings. Conditioning and extinction of opposite valences are mostly encoded in a segregated manner: conditioning neurons of one valence overlap neither with conditioning nor with extinction neurons of the opposite valence. In contrast, extinction neurons of opposite valence partially overlap, suggesting that extinction learning recruits valence-free and valence-independent mechanisms. Although the valence-specific conditioning and extinction neurons appear to be spatially segregated, opposite valences interact with each other in time. We show that prior appetitive experience delays fear extinction learning without affecting fear conditioning. These behavioral findings are corroborated at the neuronal level by the insensitivity of fear neurons to prior appetitive experience whereas the activity of fear extinction neurons is reduced by prior appetitive experience. This demonstrates that prior emotional experience influences subsequent associative learning both at the behavioral and at the neuronal level. Finally, comparison of the basal amygdala responsiveness to aversive and appetitive cues reveals a strong aversive bias of amygdala circuits. Extinction resistant neurons, which post-conditioning cue-responsiveness is maintained after extinction learning, are responsible for this aversive bias. Like the other neuronal populations identified in this study, extinction-resistant neurons of opposite valence are mostly segregated. This suggests that these neurons participate in the maintenance of valence-specific memory traces after extinction learning and thus that aversive memories are more resistant to changes in stimulus-outcome contingency. Supporting this hypothesis, we also find a strong asymmetry of extinction training between aversive and appetitive valence: aversive extinction requiring much longer training than appetitive extinction

Institutions, unemployment and inactivity in the OECD countries

This paper provides new evidence on the linkages between a large array of institutional arrangements (on product, labour and financial markets) and employment performance. Our analysis includes unemployment, inactivity and jobless rates, thus allowing us to control for possible substitution effects across situations of non-employment and to check whether institutional rigidities affecting unemployment impact inactivity along the same line. To cope with common problems related to the inclusion of time-invariant institutional variables in fixed effects models, we present results of regressions based on three different estimators: PCSE, GLS and FEVD, the last one being a new procedure specifically designed to treat slowly changing variables. New institutional series are proposed, namely to account for unemployment insurance net replacement rates and employment protection legislation (EPL). Among other results, we find strong evidence of a positive effect of EPL on employment performance as well as of possible complementarities across product and labour markets regulation

Effect of hydrostatic pressure on elastic properties of ZDTP tribofilms

Previous studies have shown that the elastic properties of Zinc Dialkyl-dithiophosphate (ZDTP) tribofilms measured by nanoindentation increase versus applied pressure (Anvil effect) [1, 2]. The aim of this paper is to demonstrate that, up to 8 GPa, this increase is a reversible phenomenon. A ZDTP tribofilm has been produced on "AISI 52100" steel substrate using a Cameron-Plint tribometer. After its formation, a hydrostatic pressure of about 8 GPa was applied during one minute on the tribofilm using a large radius steel ball ("Brinell-like" test). Nanoindentation tests were performed with a Berkovich tip on pads in order to measure and compare the mechanical properties of the tribofilm inside and outside the macroscopic plastically deformed area. Careful AFM observations have been carried out on each indent in order to take into account actual contact area. No difference in elastic properties was observed between the two areas: tribofilm modulus and pressure sensitivity are the same inside and outside the residual hemispherical print. This demonstrates that Anvil effect is a reversible phenomenon in the studied pressure range