The impact of ICT capital accumulation - A complete macroeconomic framework

The paper aims at assessing the net impact of the accumulation of Information and Communication Technologies (ICT) capital on the economy. In a first part, focusing on the supply-side of the economy, we show that the growth accounting methodology cannot provide us with a measure of the net economic impact of ICT capital accumulation, since it does not take into account substitution between production factors. We develop a theoretical framework relying on the profit optimizing behaviour of firms that enables us to quantify the missing terms. Applying to French data over the period 1995-2000, with reasonable assumptions on elasticities of substitution, we find that the net impact of ICT capital accumulation on labour productivity growth is half the one computed by growth accounting studies. In a second part, we use this long-term framework in a macroeconometric model. We find that long-term effects have a small magnitude, and the demand effects are the larger ones over the period 1995-2000. However, total impact is rather weak, less than 0.1 percentage of PIB per year.growth accounting, aggregate productivity, elasticity of substitution, information and communication technologies, macroeconometric models

Demographic changes and economic growth: a macroeconomic projection for 2020

Exploring the economic consequences of demographic changes is often carried out within simple accounting frameworks. Such approaches consist of projecting the impact of ageing on social security expenditures under exogenous assumptions about economic growth, productivity, wages and employment. Alternative attempts to consider richer interactions between economic and demographic variables are carried out with calibrated computable general equilibrium models with overlapping generations. These models are basically neoclassical. Up to now in France, this question seldom has been examined with macroeconometric models of keynesian inspiration. Studying the results provided by such models for France may therefore be of interest. This is the purpose of this work, which presents an economic outlook for 2020 carried out with MESANGE macroeconometric model. This model has short term keynesian and long term neo-classical properties. This exercise integrates the impact of demographic changes on savings, consumption, social expenditures and disequilibrium on the labour market. Labour force projections and the natural dynamics of the model lead to employment levels that remain insufficient to ensure balance in social accounts. Additional taxes would therefore be required. Two possibilities are explored: the CSG or Generalized Social Contribution (a constant tax rate on capital and labor income) or employers and employees social contributions (with or without an impact of employees contributions on the fiscal wedge). The model predicts that the level of employment is less penalised by the former modality. We also explore the consequences of tougher conditions to get full pensions which, at the 2020 horizon, would lead to a one-year increase of the age of new retirees. In this case, the increase of the CSG that would be required to meet Maastricht criteria amounts to 4.3 points. Choosing between CSG and social contributions might nevertheless depend on other considerations, such as their incidence on the relative standards of living of workers and pensioners, or the wish to keep a strong correspondence between pension benefits and contributions paid during working life.retirement, ageing, growth, sustainability of public spending

Contributionà l'étude de l'effet photoélastique dans les cristaux fortement piézoélectriques. Calcul des constantes photoélastiques de quelques cristaux piézoélectriques

The electric and elastic components of vibration modes in piezoelectric crystals have to be considered simultaneously in acoustooptic interactions. The index ellipsoid is strained by photoelastic and electrooptic effets. In strongly piezoelectric crystals, the both effects have comparable magnitudes. Therefore we have to introduce effective photoelastic constant modified by electrooptic coupling which have very different values compared to classical photoelastic constants defined with zero electric field. The effective photoelastic constants depend of the propagation direction. Their symetry degre is not entierely determined by the crystal symetry. Knowing the effective photoelastic constants proper to the (100) and (001) directions of LiNbO3 and CdS, we computed the photoelastic constants with zero electric field.Les composantes électrique et élastique des modes de vibration d'un cristal piézo-électrique doivent être considérées simultanément dans les interactions acoustooptiques. Il y a déformation de l'ellipsoïde des indices par effets photoélastique et électrooptique. Dans les cristaux fortement piézoélectriques, les deux effets ont des intensités comparables. Il faut donc introduire des constantes photoélastiques effectives modifiées par couplage électrooptique qui ont des valeurs très différentes des constantes photoélastiques classiques définies à champ électrique nul. Les constantes photoélastiques effectives n'ont pas même symétrie que les constantes photoélastiques définies à champ nul puisqu'elles dépendent de la direction de propagation considérée dans le cristal. Connaissant les constantes élastiques effectives propres aux directions (100) et (001) de LiNbO3 et de CdS, nous avons pu calculer les constantes photoélastiques à champ nul

The politics of in-work benefits: the case of the 'active income of solidarity' in France

In-work benefits have been introduced in a number of Bismarckian welfare regimes in a context of austerity despite being targeted at politically weak constituents and representing a deviation from prevailing welfare institutions. This article addresses this puzzle by looking at the introduction in 2008 of an in-work benefit scheme in France, the Active Income of Solidarity. The analysis reveals that this reform was the result of a crosscutting alliance between the conservative party and employers, as well as parts of the socialist party and the union movement. The alliance was possible thanks to actors' multiple interpretations of the reform. The reform was difficult to oppose given its support by experts and public opinion and because it entailed an increase in revenues for low-income workers