Reductive homogeneous spaces and nonassociative algebras

The purpose of these survey notes is to give a presentation of a classical theorem of Nomizu that relates the invariant affine connections on reductive homogeneous spaces and nonassociative algebras.Comment: 28 pages. The first version constituted the notes of a course given at the CIMPA research school "G\'eom\'etrie diff\'erentielle et alg\`ebres non associatives", held in Marrakech, April 13-24, 201

After The Hague, Bonn and Marrakech : the future international market for emissions permits and the issue of hot air

The main objective of this paper is to assess the Bonn-Marrakech agreement, in terms of abatement cost and emission trading as compared with the initial agreement reached in Kyoto (the Kyoto Protocol).CLIMATE CHANGE ; EMISSIONS TRADING ; INTERNATIONAL AGREEMENT

Sustainability of direct seeding versus conventional tillage

Pour analyser la durabilité du semis direct sur mulch (SDM) dans les conditions méditerranéennes, une comparaison culture traditionnelle (CT) et SDM a été réalisée sur un site expérimental à Montpellier, dans le sud de la France depuis 2000. Un blé dur a été mis en place avec différents traitements d'irrigation et d'apports d'azote en 2004. Différents paramètres du sol et de la culture ont été mesurés. En particulier, la densité du sol est légèrement accrue sous SDM et le développement racinaire, un peu moins important; le LAI et le rendement en matière sèche totale sont pratiquement équivalents à ceux de CT. Ces résultats confortent des observations antérieures sur l'efficience du SDM qui a un impact limité sur le rendement; cependant la maîtrise du semis et des adventices ont un rôle important qui doit s'appuyer sur des choix techniques adéquats et la rotation des cultures. (Résumé d'auteur

Magnitude of rift-related burial and orogenic contraction in the Marrakech High Atlas revealed by zircon (U-Th)/He thermochronology and thermal modelling

The Atlas of Morocco is a continental rift developed during the Triassic-Jurassic and moderately inverted during the Cenozoic. The High Atlas south of Marrakech, with exposures of basement and Triassic early synrift deposits, has been viewed as a high during the Mesozoic rifting. First zircon (U-Th)/He ages and thermal models obtained from 42 samples in the Marrakech High Atlas following two NNW-SSE transects across the mountain belt reveal that in contrast to previous models, the Triassic-Jurassic rift was well developed in the Marrakech High Atlas (with more than 4.5-6 km of rift-related deposits). Middle Jurassic-Early Cretaceous zHe cooling ages obtained indicate that rift-related subsidence in the Marrakech High Atlas finished in the Middle Jurassic and was followed by a period of exhumation where 2-3 km of rock were eroded. Thermal models from zHe data provide the first thermochronologic clue for a Late Cretaceous initiation of the Atlas compression-driven exhumation in the inner parts of the Marrakech High Atlas. The Triassic-Jurassic basin reconstruction assisted by thermochronology highlights a key role of inherited basement anisotropy in rift orientation and evolution, and on its subsequent inversion. Comparison of present-day and restored sections to the rifting stage aided by thermochronology suggests minimum values of total orogenic shortening in the Marrakech High Atlas of 13 to 14 km (21 to 17%), with exhumation of 1 to more than 5 km of rocks. Similar zHe ages on both sides of the Tizi n'Test fault evince minor vertical movements along the fault during the Atlas orogeny

Changes in Antioxidant Enzymes Activity and Oxidative Damage in Four Argania spinosa Ecotypes Under Water Stress Conditions

_Argania spinosa_ L. Skell, a tree endemic of Morocco, grows in semiarid and arid areas. Biochemical response to drought in four ecotypes of the _A. spinosa_ was compared. Choice of ecotypes was based on evident differences in geographical features in south-west Morocco: two coastal ecotypes (Essaouira and Agadir) and two paralittorale ecotypes (Aoulouz and Lakhssas). Lipid peroxidation (malonyldialdehyde (MDA)), content of endogenous hydrogen peroxide (H2O2) and antioxidant enzyme system (Catalase (CAT), Ascorbate peroxidase (APX), Total peroxidase (POD) and Polyphenoloxidase (PPO) were measured in control (100% relative humidity (RH) at field capacity (FC)) and water-stressed plants (50 and 25% RH at FC). For all ecotypes, drought stress significantly increased the contents of MDA and H2O2 and an ecotype effect was noted. According Two-way ANOVA analysis, the ecotype x watering regime interaction was highly significant. We found an increase in the activities of the four ROS-scavenging enzymes and an ecotype effect was noted. Ecotype x watering regime interaction shows that only the CAT and APX activities were significant. Highest values of POD and PPO activities were found in both paralittorale ecotypes. Increase in antioxidant enzyme activities appears to be an adaptive response to restore the reactive oxygen species in their homeostasis. The four study ecotypes were separated by two discriminant functions obtained by canonical discriminant analysis. Coastal ecotypes are separated from the paralittorale ecotypes mainly by POD and PPO activities and MDA content

Reconstructing Climate Policy: Beyond Kyoto

In their comprehensive analysis of the Kyoto Protocol and climate policy, Richard B. Stewart and Jonathan B. Wiener examine the current impasse in climate policy and the potential steps nations can take to reduce greenhouse gases. They summarize the current state of information regarding the extent of global warming that would be caused by increasing uncontrolled greenhouse gas emissions. They explain why participation by all major greenhouse gas-emitting countries is essential to curb future greenhouse gas emissions and also note the significant obstacles to obtaining such participation. Stewart and Wiener argue it is in the national interest of the United States to participate in such a regime, provided that it is well designed. They discuss the elements of sound climate regulatory design, including maximum use of economic incentives, the comprehensive approach, and other flexibility mechanisms; participation by all major emitting countries, including developing countries; regulatory targets based on longer-term emissions pathways set to maximize net social benefits; and effective arrangements to ensure compliance with regulatory obligations by nations and sources. After evaluating the successes and failures of the Kyoto Protocol in light of those elements, the authors propose a series of U.S. initiatives at the international and domestic levels, with the aim of engaging the United States and major developing country emitters such as China in the global greenhouse gas regulatory effort and correcting the remaining defects in the design of the Kyoto Protocol. Although several alternatives to the current Kyoto Protocol regime have been proposed, Stewart and Wiener argue that the best approach for surmounting the current global climate policy impasse is a new strategy that would lead, sooner or later, to simultaneous accession by the United States and China (and other major developing country emitters) to a modified and improved version of the Kyoto Protocol agreement