Réseaux et territoires : la construction d'une problématique

En choisissant une approche simultanée de plusieurs secteurs concernés par les schémas de service collectifs (TIC, Energie et Transports), le groupe de prospective s'est orienté vers une réflexion transversale sur la dynamique entre les réseaux et le territoire. Dans ce but, l'article propose d'abord une approche croisée, deux par deux, des relations entre les secteurs concernés. Puis en adoptant une vision synthétique, il propose une démarche distinguant six champs d'analyse pour comprendre les relations entre nouvelle donne dans les industries de réseau et évolution des territoires. A partir de ces éléments, la démarche prospective dispose d'un cadre qui servira de base au fonctionnement du groupe au cours de l'année 2001.-----------------------------------------------Cet article vous est proposé avec l'aimable autorisation des auteurs et de l'éditeur, DIACT. La présente version en PDF est sous le copyright de la DIACT (http://www.diact.gouv.fr/) - 2001. Ce document est protégé en vertu de la loi du droit d'auteur.Réseaux ; territoires ; schémas de service collectif ; déréglementation ; normes ; valeurs ; usagers ; citoyens

Ten Years of Valuation of the Local Impact of Atmospheric Pollution: from Scientific Assessments to Political Decisions

This paper focuses on the economic valuation of the impact of local air pollution. Two main issues are considered: 1. The scientific issue: what is estimated, how and why? The main studies from the nineties are presented here. Two strong issues are stressed, with the diversity of valuation methods, on the one hand, and the debates on how to take the long term into account and the discount technique, on the other. 2. The political issue: how the results from the economic field are analysed and used to establish official values for public policies? The methods used in the transport sector in three different European countries (France, Sweden and Switzerland) are studied here.To conclude, we highlight the discrepancy between these two processes and, wherever possible, offer solutions to reach better synergy.Local air pollution ; External costs ; Economic valuation ; Official values ; Public decision ; International comparison

Mobilité urbaine : cinq scénarios pour un débat

Ce document propose cinq scénarios contrastés d'évolution de la mobilité urbaine. Il constitue, sous la forme d'une note de travail, un des premiers volets de la réflexion engagée au début de l'année 2000, parle Centre de Prospective et de Veille Scientifique de la DRAST sur la prospective de la mobilité. Cet exercice de scénarisation, comme l'ensemble du programme dans lequel il s'intègre, n'aurait pu cependant être mené à bien sans l'appui de la Mission de recherche sur les transports et du PREDIT, qui ont dès le départ ont soutenu l'initiative (G. Brun).Le texte de ces scénarios a été, pour l'essentiel, écrit par trois auteurs :Yves Crozet, Jean-Pierre Orfeuil, et Marie-Hélène Massot. Mais les idées exprimées sont, plus généralement, le fruit d'un travail collectif mené par un groupe d'une dizaine d'experts appelés ici, pour simplifier, le“groupe de Batz” – du nom du lieu où la structure des scénarios a été définie.Composition du groupe d'experts CPVS-MRT sur la prospective de la mobilité urbaine (“Groupe de Batz”).Animateurs : Serge Wachter ; Jacques Theys.Membres rédacteurs : Yves Crozet ; Jean-Pierre Orfeuil ; Marie-Hélène Massot ; Marc Weil ; François Bellanger ; Vincent Fouchier.Membres non rédacteurs : Gérard Brun ; Eliane de Vendeuvre ; Michel Bonnet.scénarios ; évolution ; prévision de la demande ; mobilité urbaine ; Politique des transports urbains

Overview of Infrastructure Charging, part 4, IMPROVERAIL Project Deliverable 9, “Improved Data Background to Support Current and Future Infrastructure Charging Systems”

Improverail aims are to further support the establishment of railway infrastructure management in accordance with Directive 91/440, as well as the new railway infrastructure directives, by developing the necessary tools for modelling the management of railway infrastructure; by evaluating improved methods for capacity and resources management, which allow the improvement of the Life Cycle Costs (LCC) calculating methods, including elements related to vehicle - infrastructure interaction and external costs; and by improving data background in support of charging for use of railway infrastructure. To achieve these objectives, Improverail is organised along 8 workpackages, with specific objectives, responding to the requirements of the task 2.2.1/10 of the 2nd call made in the 5th RTD Framework Programme in December 1999.This part is the task 7.1 (Review of infrastructure charging systems) to the workpackage 7 (Analysis of the relation between infrastructure cost variation and diversity of infrastructure charging systems).Before explaining the economic characteristics of railway and his basic pricing principles, authors must specify the objectives of railways infrastructure charging.principle of pricing ; rail infrastructure charging ; public service obligation ; rail charging practice ; Europe ; Improverail

Dix ans de monétarisation des effets locaux de la pollution atmosphérique : des évaluations scientifiques aux décisions politiques

Cette communication s'intéresse à la valorisation monétaire des impacts environnementaux de la pollution atmosphérique locale. Comment, d'un côté, ces chiffres sont-ils construits par les économistes, et comment, de l'autre, sont-ils repris et utilisés pour établir des valeurs officielles dans le cadre des politiques publiques ? Nous mettons en lumière les écarts existant entre les deux et proposons des solutions pour les réduire.Pollution locale ; effets ; monétarisation ; actualisation ; valeurs tutélaires ; décision publique ; comparaison internationale

Ribulose-1,5-bisphosphate regeneration in the Calvin-Benson-Bassham cycle: Focus on the last three enzymatic steps that allow the formation of Rubisco substrate

The Calvin-Benson-Bassham (CBB) cycle comprises the metabolic phase of photosynthesis and is responsible for carbon fixation and the production of sugar phosphates. The first step of the cycle involves the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) which catalyzes the incorporation of inorganic carbon into 3-phosphoglyceric acid (3PGA). The following steps include ten enzymes that catalyze the regeneration of ribulose-1,5-bisphosphate (RuBP), the substrate of Rubisco. While it is well established that Rubisco activity acts as a limiting step of the cycle, recent modeling studies and experimental evidence have shown that the efficiency of the pathway is also impacted by the regeneration of the Rubisco substrate itself. In this work, we review the current understanding of the structural and catalytic features of the photosynthetic enzymes that catalyze the last three steps of the regeneration phase, namely ribose-5-phosphate isomerase (RPI), ribulose-5-phosphate epimerase (RPE), and phosphoribulokinase (PRK). In addition, the redox- and metabolic-based regulatory mechanisms targeting the three enzymes are also discussed. Overall, this review highlights the importance of understudied steps in the CBB cycle and provides direction for future research aimed at improving plant productivity

Dissection of miRNA Pathways Using Arabidopsis Mesophyll Protoplasts

MicroRNAs (miRNAs) control gene expression mostly post-transcriptionally by guiding transcript cleavage and/or translational repression of complementary mRNA targets, thereby regulating developmental processes and stress responses. Despite the remarkable expansion of the field, the mechanisms underlying miRNA activity are not fully understood. In this article, we describe a transient expression system in Arabidopsis mesophyll protoplasts, which is highly amenable for the dissection of miRNA pathways. We show that by transiently overexpressing primary miRNAs and target mimics, we can manipulate miRNA levels and consequently impact on their targets. Furthermore, we developed a set of luciferase-based sensors for quantifying miRNA activity that respond specifically to both endogenous and overexpressed miRNAs and target mimics. We demonstrate that these miRNA sensors can be used to test the impact of putative components of the miRNA pathway on miRNA activity, as well as the impact of specific mutations, by either overexpression or the use of protoplasts from the corresponding mutants. We further show that our miRNA sensors can be used for investigating the effect of chemicals on miRNA activity. Our cell-based transient expression system is fast and easy to set up, and generates quantitative results, being a powerful tool for assaying miRNA activity in vivo.Fundação para a Ciência e Tecnologia fellowships: (SFRH/BD/33563/2008, SFRH/BPD/47280/2008, SFRH/BPD/79255/2011) and grant: (PTCD/BIA-BCM/107924/2008); EMBO fellowship & EMBO Installation program; Deutsche Forschungsgemeinschaft grant: (SPP1530); Max Planck Society grant

Parc automobile et effet de serre. Agir sur le parc automobile pour réduire l’effet de serre

International audienceCette étude traite des conditions du renouvellement du parc automobile afin de mieux maîtriser l'impact sur l'effet de serre. Quels sont les critères d'achat et les conditions d'utilisation des véhicules ? Quelles politiques publiques peuvent orienter le choix des consommateurs et l'offre des constructeurs vers des véhicules moins polluants ? Divers instruments de politiques publiques sont analysés

SUMOylation represses SnRK1 signaling in Arabidopsis

The SnRK1 protein kinase balances cellular energy levels in accordance with extracellular conditions and is thereby key for plant stress tolerance. In addition, SnRK1 has been implicated in numerous growth and developmental processes from seed filling and maturation to flowering and senescence. Despite its importance, the mechanisms that regulate SnRK1 activity are poorly understood. Here, we demonstrate that the SnRK1 complex is SUMOylated on multiple subunits and identify SIZ1 as the E3 Small Ubiquitin-like Modifier (SUMO) ligase responsible for this modification. We further show that SnRK1 is ubiquitinated in a SIZ1-dependent manner, causing its degradation through the proteasome. In consequence, SnRK1 degradation is deficient in siz1-2 mutants, leading to its accumulation and hyperactivation of SnRK1 signaling. Finally, SnRK1 degradation is strictly dependent on its activity, as inactive SnRK1 variants are aberrantly stable but recover normal degradation when expressed as SUMO mimetics. Altogether, our data suggest that active SnRK1 triggers its own SUMOylation and degradation, establishing a negative feedback loop that attenuates SnRK1 signaling and prevents detrimental hyperactivation of stress responses.Austrian Science Foundation FWF grant: (P25488, P23435); EMBO Installation program; FCT grants: (PTDC/BIA-PLA/3937/2012, SFRH/BD/51627/2011,SFRH/BPD/79255/2011); UID/Multi/04551/2013_Research unit GREEN-it_'Bioresources for Sustainability’

Structural basis for the magnesium-dependent activation of transketolase from Chlamydomonas reinhardtii

Background In photosynthetic organisms, transketolase (TK) is involved in the Calvin-Benson cycle and participates to the regeneration of ribulose-5-phosphate. Previous studies demonstrated that TK catalysis is strictly dependent on thiamine pyrophosphate (TPP) and divalent ions such as Mg2 +. Methods TK from the unicellular green alga Chlamydomonas reinhardtii (CrTK) was recombinantly produced and purified to homogeneity. Biochemical properties of the CrTK enzyme were delineated by activity assays and its structural features determined by CD analysis and X-ray crystallography. Results CrTK is homodimeric and its catalysis depends on the reconstitution of the holo-enzyme in the presence of both TPP and Mg2 +. Activity measurements and CD analysis revealed that the formation of fully active holo-CrTK is Mg2 +-dependent and proceeds with a slow kinetics. The 3Dâstructure of CrTK without cofactors (CrTKapo) shows that two portions of the active site are flexible and disordered while they adopt an ordered conformation in the holo-form. Oxidative treatments revealed that Mg2 +participates in the redox control of CrTK by changing its propensity to be inactivated by oxidation. Indeed, the activity of holo-form is unaffected by oxidation whereas CrTK in the apo-form or reconstituted with the sole TPP show a strong sensitivity to oxidative inactivation. Conclusion These evidences indicate that Mg2 +is fundamental to allow gradual conformational arrangements suited for optimal catalysis. Moreover, Mg2 +is involved in the control of redox sensitivity of CrTK. General significance The importance of Mg2 +in the functionality and redox sensitivity of CrTK is correlated to light-dependent fluctuations of Mg2 +in chloroplasts