A discrete nonetheless remarkable brick in de Sitter: the "massless minimally coupled field"

Over the last ten years interest in the physics of de Sitter spacetime has been growing very fast. Besides the supposed existence of a "de sitterian period" in inflation theories, the observational evidence of an acceleration of the universe expansion (interpreted as a positive cosmological constant or a "dark energy" or some form of "quintessence") has triggered a lot of attention in the physics community. A specific de sitterian field called "massless minimally coupled field" (mmc) plays a fundamental role in inflation models and in the construction of the de sitterian gravitational field. A covariant quantization of the mmc field, `a la Krein-Gupta-Bleuler was proposed in [1]. In this talk, we will review this construction and explain the relevance of such a field in the construction of a massless spin 2 field in de Sitter space-time.Comment: Proceedings of the XXVII Colloquium on Group Theoretical Methods in Physics, Yerevan, August 200

Streamlined eco-engineering approach helps define environmental flows for tropical Andean headwaters

Applying the environmental flows concept to human-altered lotic ecosystems continues to face many practical challenges and barriers. Here, we modify a previously proposed framework, the Eco-Engineering Decision Scaling, for application to part of the water supply system of Quito, Ecuador. Specifically, we used feedback from engineers and water managers to develop a common set of metrics for defining flow-ecology relationships and assess managed-flow impacts on stream ecology. At 12 sites over 3 years, we collected flow and benthic invertebrate data (taxonomic richness, taxa important for fish, functional feeding groups, and water quality-sensitive taxa) during wet and dry seasons. We then used these data to identify flow thresholds (relative to unmanaged flows) where flow withdrawal caused visible ecological impacts. For this system, reduction of flow to 20% of the annual median was detrimental to benthic communities, while reductions to 40% of the annual median flow caused a variety of responses in the system. A trade-off analysis of weighted metrics showed that a 50% benthic fauna richness could be sustained if dry season flows were maintained between 28% and 40% of the unmanaged median annual flow. This study provides a roadmap for bridging between eco-engineering theoretical frameworks and the adoption of the environmental flows concept as actionable management thresholds

Introduction: The EU in International Trade Negotiations

This special issue presents new research on the EU's role in international trade negotiations. In the introduction, we sketch out the relevance of this topic, introduce some of the core institutional features of trade policy-making in the EU, review the existing literature dealing with the EU in international trade negotiations, and briefly present the contributions included in this issue. Copyright (c) 2007 The Author(s); Journal compilation (c) 2007 Blackwell Publishing Ltd.