Trade in services : How does it work ?

While services represent nearly 70 % of value added in all OECD countries, only a fifth of trade in goods and services is due to cross-border supply of services. Then internationalisation of services occurs by commercial presence of firms in host countries, its impact on white collar employment is limited and only unskilled workers incur falls in wage. As for temporary movement of people, Mode 4 is very difficult to measure either by trade or migration statistics. In the paper we show that the divergence between the preponderance of services in national activities and its weakness in international transactions is due to the importance of non tradeable industries, for which the degree is week and contrasts with activities implied in international competition.Trade in services ; Comparative Advantage ; Temporary movement of persons

The Feldstein-Horioka Puzzle: a Panel SmoothTransition Regression Approach

This paper proposes an original framework to determine the relative influence of fivefactors on the Feldstein and Horioka result of OECD countries with a strong saving-investment association. Based on panel threshold regression models, we establishcountry-specific and time-specific saving retention coefficients for 24 OECD coun-tries over the period 1960-2000. These coefficients are assumed to change smoothly,as a function of five threshold variables, considered as the most important in theliterature devoted to the Feldstein and Horioka puzzle. The results show that; de-gree of openness, country size and current account to GDP ratios have the greatestinfluence on the investment-saving relationship.Feldstein Horioka puzzle, Panel Smooth Threshold Regression models,saving-investment association, capital mobility .

Electron Coherence in Mesoscopic Kondo Wires

We present measurements of the magnetoresistance of long and narrow quasi one-dimensional gold wires containing magnetic iron impurities. The electron phase coherence time extracted from the weak antilocalisation shows a pronounced plateau in a temperature region of 300 mK - 800 mK, associated with the phase breaking due to the Kondo effect. Below the Kondo temperature, the phase coherence time increases, as expected in the framework of Kondo physics. At much lower temperatures, the phase coherence time saturates again, in contradiction with standard Fermi liquid theory. In the same temperature regime, the resistivity curve displays a characteristic maximum at zero magnetic field, associated with the formation of a spin glass state. We argue that the interactions between the magnetic moments are responsible for the low temperature saturation of the phase coherence time.Comment: To appear in Advances in Solid State Physics, Vol 43, edited by B. Kramer (Springer Verlag, Berlin 2003

Spatial and temporal variability of plant-available soil water in Congo Basin and its relationship with tree species distributions

Regional-scale patterns of tropical rainforest tree composition can be due to climate (rainfall, dry season length), geology and/or soil properties (chemical fertility, available water). In Amazonia, soil fertility and dry season length appears to be the main factor to explain this pattern. However, in the Congo Basin, geology has been proposed to explain the pattern of some commercial timber species. Since the geological substrates of this area have similar chemical properties, we hypothesized that this pattern could be explained by the plant-available soil water (PAW). We used a soil water balance model similar to RisQue in the Congo Basin over the period from 2000 to 2010, with a decade time step, and with a spatial resolution of 8 km. The input parameters of this model were the maximum plant-available soil water (PAWmax), rainfall and evapotranspiration. The output parameter was the maximum number of successive decades when PAW was null, named extreme drought index (EDI). Finally we carried out a map of EDI at Congo Basin scale that we compared with maps of the spatial pattern of 31 commercial species. We showed that Arenosols, as expected, but also other soils like Ferralsols, have the lowest PAWmax of the Congo Basin. We evidenced no or low correlations between the map of EDI and maps of the spatial pattern of each of the 31 commercial species. Other factors, not taken into account in this study, might explain this result like the water table level and variable forest rooting depth in function of soil type. (Résumé d'auteur

Cross-waves induced by the vertical oscillation of a fully immersed vertical plate

Capillary waves excited by the vertical oscillations of a thin elongated plate below an air-water interface are analyzed using time-resolved measurements of the surface topography. A parametric instability is observed above a well defined acceleration threshold, resulting in a so-called cross-wave, a staggered wave pattern localized near the wavemaker and oscillating at half the forcing frequency. This cross-wave, which is stationary along the wavemaker but propagative away from it, is described as the superposition of two almost anti-parallel propagating parametric waves making a small angle of the order of $20^\mathrm{o}$ with the wavemaker edge. This contrasts with the classical Faraday parametric waves, which are exactly stationnary because of the homogeneity of the forcing. Our observations suggest that the selection of the cross-wave angle results from a resonant mechanism between the two parametric waves and a characteristic length of the surface deformation above the wavemaker.Comment: to appear in Physics of Fluid

Aharonov-Bohm effect in higher genus materials

Flux periodicity of conducting electrons on a closed surface with genus two $g=2$ (double torus) are investigated theoretically. We examine flux periodicity of the ground-state energy and of the wave functions as a function of applied magnetic field. A fundamental flux period of the ground-state energy is twice a fundamental unit of magnetic flux for uniformly applied magnetic field, which is shown to be valid for a simple ladder geometry and carbon double torus. Flux periodicity of the wave functions in a double torus is complicate as compared with a simple torus ($g=1$), and an adiabatic addition of magnetic fluxes does not provide a good quantum number for the energy eigenstates. The results are extended to higher genus materials and the implications of the results are discussed.Comment: 4 pages, 6 figure