[en] The European commission adopted the directive on 'the common rules for the creation of the internal electricity market' in 1996. After about ten years, it seems that in many smaller countries the historical producer remains dominant in the national market. This is the case for Belgium, where historical reasons and limited interconnection capacity resulted in a market share between 70% and 80% (depending on whether the interconnections are taken into account) for the historical producer Electrabel. This might potentially lead to an abuse of market power. Moreover, the wholesale margins seem to be higher in Belgium than e.g. in the Netherlands. Many argue that divestiture or additional VPP might solve the problem. This paper argues that there is no doubt whatsoever that divestiture and VPP will increase competition. However, whether it will also increase efficiency depends strongly on the specific context. It is shown that the existence of margins might be due to other causes than the abuse of market power and as a consequence that divestiture and VPP might not be the solution. (Author)

[en] The European Commission adopted the directive on 'the common rules for the creation of the internal electricity market' in 1996. After about ten years, it seems that in many smaller countries the historical producer remains dominant in the national market. This is the case for Belgium, where historical reasons and limited interconnection capacity resulted in a market share between 70 % and 80 % (depending on whether or not the interconnections are taken into account) for the historical producer Electrabel. Moreover, the wholesale margins seem to be higher in Belgium than e.g. in the Netherlands. Many argue that divestiture or additional Virtual Power Plants (VPP) might solve the problem. This paper argues that the efficiency of such solutions depends strongly on the specific context. It is shown that the existence of margins might be due to other causes than the abuse of market power and as a consequence that divestiture and VPP might not be the solution. (author)

[en] In view of their special characteristics, network industries have for quite a long time been considered as (natural) monopolies. Network externalities and economies of scale in particular justified this (natural) monopoly thesis. Since the last decade of the past century, however, a trend towards deregulation of such industries has been observed worldwide. This trend started with the successful introduction of competition in the telecommunications sector. The success in that sector is often used as an argument for opening up other network industries to competition as well. The study analyses whether this reasoning can be applied to the electricity sector. At first glance, the sectors electricity and telecommunications seem very similar, as both are network industries having been characterised for a long time by economies of scale, but for which technological progress may have put an end to this scale effect. However, the study points out that there are important differences. In the telecommunications sector, technological progress on the supply side has been accompanied by a strong growth in demand. There is no such demand side effect in the electricity branch. Moreover, due to physical characteristics, the electricity sector seems to be more complicated. In order to introduce competition, the sector has to be split up into sub-sectors (production, transmission, distribution and supply). Only two segments, production and supply, are considered as open markets; transmission and distribution, on the other hand, remain monopolies. This splitting up, however, entails a new kind of costs, the so-called transaction costs. As such the gains from the liberalization in certain segments might (partly) offset increase in the transaction costs resulting from vertical disintegration. (authors)

[en] Published in summary form only

[en] During the years 1999-2005 a series of incubation experiments were conducted under controlled conditions to investigate the effect of plant litter quality and residue location (surface vs. incorporated) on residue decomposition, C storage and N dynamics in soils. Comparisons between decomposition of roots and other plant parts (leaves and stems) were emphasized in order to better evaluate the contribution of root systems to nutrient release and soil C sequestration. The second aspect investigated was the decomposition of residues from forest, grassland and annual crops. The aim was to assess the relative effects of soil past history and residue quality on short term biodegradation. During the initial phase of decomposition, the principal factor determining decomposition kinetics was the nature of the added carbon, which strongly affected the nature and activity of the decomposing microbial biomass. Initial C mineralization (after 3 d of incubation) was significantly related to the percentage of soluble compounds in the residue, while after 142 d, a linear relationship was observed between cumulative C mineralization and the percentage of the lignin-like fraction. The amount of N mineralized was strongly related to the initial N content of the residues. No specific interaction with the origin of the residues (agro-, pasture or forest ecosystem) was observed, indicating that concepts for describing crop residue decomposition may be generalized for the decomposition of grass roots and tree leaves, and therefore for mixed residues in agroforestry systems. The C and N mineralization of leaf and stem residues from four tropical species were related to their biochemical composition and could be predicted from their N content, thus indicating a similar behaviour for a range of temperate crop residues. C mineralized from roots was 20 to 30% less than for leaves and stems, and this was assumed to be related to the presence of a high lignin-suberin content. The lower decomposition of root-C translated into higher stabilisation of root-derived C into the soil, suggesting a higher contribution of root systems than above ground parts to the soil organic C pool. This suggests that inputs of C from roots contribute proportionally more than other plant parts to the long-term build up of soil organic matter. When residues were placed on the soil surface or were incorporated into the soil when N availability was not a factor limiting decomposition, and where there was no gradient in soil and air humidity and temperature, there was no significant effect of placement on C dynamics and little difference in N dynamics, whatever the biochemical quality of the residues. When residues were placed either at the soil surface as a mulch or incorporated, in an experimental system that mimics actual conditions, i.e. allowing water and solute transport into the soil after rain and evaporation, the main effect of residue location was a change in evaporation rate, and therefore in soil moisture content and distribution, acting in turn on microbial activity and N mineralization. (author)

[en] We experimentally study the spatial properties of the field generated by spontaneous parametric down-conversion (SPDC) when the pump laser beam is strongly focused in the nonlinear crystal. Special attention is paid to classical intensity measurements with a CCD camera. We introduce the concept of a classical equivalent source that replicates all the coherence properties of SPDC light and explains all our experimental results. We show that, in contrast with experiments with a well-collimated pump, here both the phase-matching conditions and the position of the focusing plane determine the measured intensity profiles in the image plane of the crystal. The transition from the near-field regime to the far field is investigated. Measurements of two-photon correlations under strong focusing are also presented and the special features thereof are discussed.

[en] The general objective of this project was to contribute to the evaluation of land use and management impacts on C sequestration and nitrogen dynamics in soils. The land used through the presence/absence of crops and their species, and the land management through tillage, localisation of crop residues, fertilizer applications,... are important factors that affect the dynamics of organic matters in soils, particularly the mineralization of C and N, the losses to the atmosphere and hydrosphere, the retention of carbon into the soil. This project was conducted by four research groups, three of them having expertise in nutrient cycling of three major agro-ecosystems (arable crops, grasslands, forests) and the fourth one having expertise in modelling long term effects of land use on C storage into the soils. Within this common project one major objective was to better understand the fate of plant litter entering the soil either as above litter or as root litter. The focus was put on two factors that particularly affect decomposition: the initial biochemical quality of plant litter, and the location of the decomposing litter. One innovative aspect of the project was the use of stable isotope as ¹³C for carbon, based on the use of enriched or depleted ¹³C material, the only option to assess the dynamics of 'new' C entering the soil on the short term, in order to reveal the effects of decomposition factors. Another aspect was the simultaneous study of C and N. The project consisted in experiments relevant for each agro-ecosystem, in forest, grassland and arable soils for which interactions between residue quality and nitrogen availability on the one hand, residue quality and location on the other hand, was investigated. A common experiment was set up to investigate the potential degradability of the various residue used (beech leaf rape straw, young rye, Lolium and dactylic roots) in a their original soils and in a single soil was assessed. Based on these experiments, the Roth-C model of Coleman and Jenkinson (1996) was used to simulate the short term evolution of residual C, biomass C. A new parametrization based on biochemical composition of residues was proposed. (authors)

[en] Global environmental and climate conditions fluctuate on all kind of spatio-temporal scales. Some fluctuations or change/trends are not only anthropogenic, but have different regional and national signatures. While the frequency of extreme events on smaller scales is changing, the public sector and general opinion become more and more aware and concerned of local impacts from global environmental and climate changes. Indeed, negative effects and feedbacks, might occur on ecosystems, natural resources, buildings and grounds, superstructures, economies, food security, public health. This is how, during 1999, a concerted French initiative led to the research program 'Management and Impacts of Climate Change' (GICC). GICC is essentially managed by the Ministry of Ecology and Sustainable Development in close collaboration with the Inter-Ministerial Mission on Greenhouse Effect (MIES). GICC started in 1999. Its first phase (1999-2006) included four calls for proposal (1999, 2000, 2001, and 2002). In parallel and in 2003-2004, the MIES has been developing the so-called 'Climate Plan' based upon three principles : Insure that France follows agreements from the 'Kyoto Protocol'; Participate in ways and means leading to reduction of greenhouse gases by 75% in 2050; Allow for reduction of pollution from transportation means. Input from GICC Phase One final reports are contributing to 'Climate Plan'. The eight themes proposed by GICC-1 (1999-2002) are as follows: Theme 1: Evolution scenarios of the average and extreme features of the 21. Century climate; Theme 2: Interactions between climate, economy and society; related timescales; Theme 3: Role of carbon forest uptake and agricultural practices on climate policies; Theme 4: Links between national and international activities; Theme 5: Towards new inventories of GHG and aerosols (direct and indirect) emissions; Theme 6: Impacts on terrestrial biosphere; Theme 7: Impacts on hydro-systems; Theme 8: Impacts on public health. A symposium presenting the available results of the GICC first phase has taken place in MEDD, Paris, November 23-24, 2004. A final presentation workshop of the first phase took place in Paris, on May 11-12, 2006. This document is the proceedings of this scientific restitution seminar. It is organized in 9 sessions which follow the 8 themes listed above plus a round table for the status and perspectives of the GICC program. (J.S.)