Downward Wage Rigidity: a Micro-Level Empirical Analysis for France in the 90s

We use microdata to examine the existence of downward wage rigidity in France, during the second half of the 90s. We use three annual datasets : a sample of the Déclarations Annuelles de Données Sociales, the Fiscal Income Survey and the Labour Force Survey. The first two sources, compiled on behalf of the fiscal administration, are reputed to be more accurate than the last one, subject to the traditional limitations of household surveys. Indeed, we show a tendency to underdeclaration as well as massive rounding to be present in the LFS wage measure. According to standard economic analysis, wages reflect individual productivity. All mechanisms reducing the transmission of productivity shocks to wages induce by definition wage rigidity. In practice, the presence and extent of wage rigidity must be deduced from the comparison between the actual wage evolution and some « reference evolution » observed in the absence of rigidity. A classical identifying assumption holds that downward wage rigidity transforms negative variations in the reference distribution into zero variations in the actual distribution, thus inducing a spike at zero in the latter. In French data, only the LFS exhibits such a spike, which seems to stem solely from reporting errors. We investigate the presence of more complex downward wage rigidity, by testing for the symmetry of the response of wages to positive and negative productivity shocks. For that purpose, we match the employee files with a firm level dataset (Bénéfices Réels Normaux). Results suggest that wages adjust less completely in the case of negative shocks. Although this asymmetry is shown to decrease with the initial wage level, wage rigidity cannot be reduced to the sole presence of a minimum wage. In particular, it is also shown to be higher for executives, and increasing in the local rate of unemployment.Wage rigidity, Measurement errors

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

Electrocatalytic reduction of metronidazole using titanocene/Nafion®-modified graphite felt electrode

International audienceThe main objective of this study was to examine the feasibility of an electrocatalytic reduction on titanocene/Nafion®-modified graphite felt electrode, as pretreatment, before a biological treatment, for the degradation of metronidazole, a nitro biorecalcitrant pollutant. A titanium complex, know as an effective catalyst in the reduction of nitro groups, was immobilized on the electrode surface by encapsulation into a Nafion® film. The different operating conditions used to prepare the modified electrode, i. e. the initial concentrations of catalyst and Nafion® and the sonication time, were optimized and the modification of the electrode was highlighted by cyclic voltammetry and electronic scanning microscopy coupled with energy dispersive spectroscopy analysis. The results show a good stability and reproducibility of the modified electrode. Flow heterogeneous catalytic reduction of metronidazole was then carried out with the titanocene/Nafion®-modified graphite felt as working electrode. The HPLC analysis underlined the total reduction of metronidazole after 1 hour and the evolution of the biological oxygen demand to chemical oxygen demand ratio showed a significant increase of biodegradability from 0.06 before pretreatment to 0.35 ± 0.05 after electrolysis on the modified graphite felt electrode. The comparison of both homogeneous and heterogeneous reactions underlined the interest of the immobilization process that led to a higher stability of the catalyst, giving rise to a higher turnover number and an improvement of biodegradability. The stability of the modified electrode was investigated after electrolysis by cyclic voltammetry and successive electrolyses

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

Indirect electroreduction as pretreatment to enhance biodegradability of metronidazole.

International audienceThe removal of metronidazole, a biorecalcitrant antibiotic, by coupling an electrochemical reduction with a biological treatment was examined. Electroreduction was performed in a home-made flow cell at -1.2V/SCE on graphite felt. After only one pass through the cell, analysis of the electrolyzed solution showed a total degradation of metronidazole. The biodegradability estimated from the BOD5/COD ratio increased from 0.07 to 0.2, namely below the value usually considered as the limit of biodegradability (0.4). In order to improve these results, indirect electrolysis of metronidazole was performed with a titanium complex known to reduce selectively nitro compounds into amine. The catalytic activity of the titanium complex towards electroreduction of metronidazole was shown by cyclic voltammetry analyses. Indirect electrolysis led to an improvement of the biodegradability from 0.07 to 0.42. To confirm the interest of indirect electroreduction to improve the electrochemical pretreatment, biological treatment was then carried out on activated sludge after direct and indirect electrolyses; different parameters were followed during the culture such as pH, TOC and metronidazole concentration. Both electrochemical processes led to a more efficient biodegradation of metronidazole compared with the single biological treatment, leading to an overall mineralization yield for the coupling process of 85%

Impermeability effects in three-dimensional vesicles

We analyse the effects that the impermeability constraint induces on the equilibrium shapes of a three-dimensional vesicle hosting a rigid inclusion. A given alteration of the inclusion and/or vesicle parameters leads to shape modifications of different orders of magnitude, when applied to permeable or impermeable vesicles. Moreover, the enclosed-volume constraint wrecks the uniqueness of stationary equilibrium shapes, and gives rise to pear-shaped or stomatocyte-like vesicles.Comment: 16 pages, 7 figure

Two Superconducting Phases in the d=3 Hubbard Model: Phase Diagram and Specific Heat from Renormalization-Group Calculations

The phase diagram of the d=3 Hubbard model is calculated as a function of temperature and electron density n_i, in the full range of densities between 0 and 2 electrons per site, using renormalization-group theory. An antiferromagnetic phase occurs at lower temperatures, at and near the half-filling density of = 1. The antiferromagnetic phase is unstable to hole or electron doping of at most 15%, yielding to two distinct "tau" phases: for large coupling U/t, one such phase occurs between 30-35% hole or electron doping, and for small to intermediate coupling U/t another such phase occurs between 10-18% doping. Both tau phases are distinguished by non-zero hole or electron hopping expectation values at all length scales. Under further doping, the tau phases yield to hole- or electron-rich disordered phases. We have calculated the specific heat over the entire phase diagram. The low-temperature specific heat of the weak-coupling tau phase shows a BCS-type exponential decay, indicating a gap in the excitation spectrum, and a cusp singularity at the phase boundary. The strong-coupling tau phase, on the other hand, has characteristics of BEC-type superconductivity, including a critical exponent alpha approximately equal to -1, and an additional peak in the specific heat above the transition temperature indicating pair formation. In the limit of large Coulomb repulsion, the phase diagram of the tJ model is recovered.Comment: 16 pages, 10 figures; typos in Fig. 2 correcte

Self-Dual Bending Theory for Vesicles

We present a self-dual bending theory that may enable a better understanding of highly nonlinear global behavior observed in biological vesicles. Adopting this topological approach for spherical vesicles of revolution allows us to describe them as frustrated sine-Gordon kinks. Finally, to illustrate an application of our results, we consider a spherical vesicle globally distorted by two polar latex beads.Comment: 10 pages, 3 figures, LaTeX2e+IOPar

Relations between Au / Sn-W mineralizations and late hercynian granite: Preliminary results from the Schistose Domain of Galicia-Trás-os-Montes Zone, Spain

International audienceAu and W-Sn mineralization of the Schistose Domain of Galicia-Trás-os-Montes are spatially related to late hercynian granites. The Bruès (Au) and the Mina Soriana W-(Sn) deposits are studied. Both show some similarities and are assumed to form in the same tectonic and metamorphic context, on top of the granites. The role of the granite as a source for mineralizing fluids and rheological control for vein emplacement is re-adressed and discussed