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  • [hal-04780540] SOMLIT (Service d'Observation en Milieu Littoral) time series (French Research Infrastructure ILICO): long-term core parameter monitoring of French coastsThis link opens in a new windowNov 13, 2024
    SOMLIT (Service d'Observation en Milieur Littoral) : a French Coastal Monitoring Network Coastal zones are where land, ocean and atmosphere interact. They are important for the exchange of matter and energy, and play a key role in (biogeo)chemical cycles at global scale. These environments are characterised by significant spatial and temporal variability of their physico-chemical and biological parameters due to local and seasonal meteorological drivers which are exacerbated by large-scale climate drivers (e.g. global warming, modification of the wind regime) and local-scale anthropogenic drivers (e.g. nutrient cycle changes linked to the use of fertilisers or the construction of large installations such as dams). These driving mechanisms are often interconnected. In the context of global warming (due to­­ climate and human-induced changes), the identification and understanding of their impact on coastal marine and littoral ecosystems is essential. The scientific objective of SOMLIT is to 1) characterise the multi-decadal evolution of coastal marine and littoral ecosystems, and 2) determine the climatic and anthropogenic drivers. In order to meet this objective, a nationally coordinated multi-site monitoring system was set up in the mid-1990s. The observation strategy is the same for each of the 12 monitored ecosystems with fortnightly sampling and/or measurements, at high tide (for sites subject to tides): 1) in surface-water for a range of 15 parameters (temperature, salinity, dissolved oxygen, pH, nitrate, nitrite, ammonium, phosphate, silicate, suspended particulate matter, chlorophyll a, particulate organic carbon and nitrogen and stable isotopes of particulate organic carbon and nitrogen), 2) in surface-water for a range of 26 parameters of numbering and optical characteristics of pico- and nanoplankton), and 3) along the water column for temperature, salinity, fluorescence and PAR (vertical profiles of multi-parameter probes). SOMLIT’s activities are carried out under a quality assurance / quality control process based on the ISO 17025 standard. SOMLIT’s service provision objectives are to provide data and logistical support for research and other observation activities. SOMLIT has been officially accredited since 1996 as one of the CNRS (French National Centre for Scientific Research) National Observation Services (SNO). SOMLIT’s coordination is hosted by the Observatoire Aquitain des Sciences de l'Univers (University of Bordeaux / CNRS) and the service relies on strong partnerships with nine other institutions (University of Lille, University of the Littoral Opal Coast, University of Caen Normandy, Sorbonne University, University of Western Brittany, La Rochelle University, University of Montpellier, Aix Marseille University, National Museum of Natural History). SOMLIT is one of the nine networks that compose France’s Coastal Research Infrastructure (ILICO). SOMLIT has strong ties with ILICO’s other networks such as the SNOs MOOSE (Mediterranean Ocean Observing System on Environment), PHYTOBS (microphytoplankton monitoring) and COAST-HF (Coastal Ocean Observing System - High Frequency).
  • [hal-04083118] Data quality control considerations in multivariate environmental monitoring: experience of the French coastal network SOMLITThis link opens in a new windowApr 26, 2023
    Introduction While crucial to ensuring the production of accurate and high-quality data—and to avoid erroneous conclusions—data quality control (QC) in environmental monitoring datasets is still poorly documented. Methods With a focus on annual inter-laboratory comparison (ILC) exercises performed in the context of the French coastal monitoring SOMLIT network, we share here a pragmatic approach to QC, which allows the calculation of systematic and random errors, measurement uncertainty, and individual performance. After an overview of the different QC actions applied to fulfill requirements for quality and competence, we report equipment, accommodation, design of the ILC exercises, and statistical methodology specially adapted to small environmental networks (<20 laboratories) and multivariate datasets. Finally, the expanded uncertainty of measurement for 20 environmental variables routinely measured by SOMLIT from discrete sampling—including Essential Ocean Variables—is provided. Results, Discussion, Conclusion The examination of the temporal variations (2001–2021) in the repeatability, reproducibility, and trueness of the SOMLIT network over time confirms the essential role of ILC exercises as a tool for the continuous improvement of data quality in environmental monitoring datasets.
  • [insu-04723432] The Last Fissural Eruptions of the Manda Hararo Magmatic Segment, Central Afar (Ethiopia), Constrained from New cosmogenic AgesThis link opens in a new windowOct 7, 2024
    The Afar depression at the northern end of the East African Rift system is presently experiencing the final stage of continental break-up and progressive onset of steady magmatic spreading. The Magmatic Rift Segments in Afar broadly analogous to those observed within the mid oceanic ridges, offer the opportunity to study both mantle and crustal processes. Investigating the crustal architecture of those magmatic segments represents a key aspect to decipher fundamental parameters that control focussing of magmatic and tectonic activity during the generation of magmatic crust. Here, we present the typical organization of a 32 km long subsegment of the Manda Hararo magmatic rift system, with fissural activities symmetrical to an apparent mid segment magmatic reservoir and establish geochronology of the last eruptive history. We combine field investigations, precise mapping of volcanological and tectonic features, cosmogenic 36Cl exposure dating and geochemical analysis of lavas to constrain the temporal frame and the dynamics of magmatic processes. Our results show that the recent historical volcanic events (~ 500 to 2000 years) are sourced from calderas and fissures representing an alternating sequence of effusive and explosive (block fields) activities related to a coherent rifting episode along a single self-consistent magmatic sub-segment. Those recent fissural flows resurfaced a large portion of the segment and emplaced on older thick pahoehoe flows with a rather long lag-time of about 75 kyr separating the two episodes. Strongly contrasted geochemical signatures are also observed between those two volcanic episodes, with more differentiated and trace elements enriched basalts for the recent one, compared to the older one which are characterized by a unusual depleted signature. These new results for the Central Afar Manda Hararo rift have important implications for: (i) the local hazards along the segments, and (ii) the volcano-tectonic organization of the segment with coexistence of contrasted melt reservoirs on the underlying transcrustal plumbing system.
  • [hal-01589999] Introduction: recent developments of switching models for financial dataThis link opens in a new windowFeb 13, 2024
    A selection of papers presented at the second International Workshop on Financial Markets and Nonlinear Dynamics (FMND) which was organized in Paris on June 4–5, 2015 is published in this special issue of Studies in Nonlinear Dynamics and Econometrics. This international workshop organized every 2 years in Paris is designed to enable academics and professional economists and econometricians to discuss their latest research findings and the recent developments in financial econometrics, with a focus on nonlinear econometrics and high frequency data modeling. Accordingly, the selected papers of this issue discuss some challenging new topics of research using nonlinear and switching models. [...]
  • [hal-01978664] Recent developments in macro-econometric modeling: theory and applicationsThis link opens in a new windowJun 26, 2023
    Developments in macro-econometrics have been evolving since the aftermath of the Second World War. Essentially, macro-econometrics benefited from the development of mathematical, statistical, and econometric tools. Such a research programme has attained a meaningful success as the methods of macro-econometrics have been used widely over about half a century now to check the implications of economic theories, to model macroeconomic relationships, to forecast business cycles, and to helppolicymakers to make appropriate decisions.[...]
  • [hal-03825278] Financial market reaction to cyberattacksThis link opens in a new windowOct 22, 2022
    Drawing upon an extensive dataset comprising 3,680 cyberattacks on firms listed in 5 stock markets, our main objective is to ascertain the financial market reaction based on a hybrid valuation inspired by the event study methodology and a counterfactual analysis. Analyses concern three dates that are specific to cyberattacks: 1) the accident date; 2) the first notice date; and 3) the original loss start date. Results indicate that there is a negative abnormal return for the NASDAQ after the accident date. The reactions of the NASDAQ and NYSE are similar, and negative for the first notice date but positive after the original loss start date. In the European context, cumulative abnormal returns are negative for French and German companies after the first notice date.
  • [hal-03844488] De la subsidiarité et de son opérationnalisationThis link opens in a new windowNov 8, 2022
    Le numéro 48 du volume 11 de la RIMHE porte sur la subsidiarité, concept issu de la philosophie politique et instaurant le principe que les seules décisions et les seules actions qui incombent à une autorité supérieure sont celles qui ne peuvent pas être prises ou réalisées à l’échelon inférieur. Les trois articles de recherche et les deux retours d’expérience publiés contribuent à en questionner les notions associées, telles que l’autonomie, la responsabilisation ou l’exercice de l’autorité, de même que la note de lecture éclaire la réflexion en soulignant leurs rapports ambigus avec la valeur d’égalité centrale dans nos sociétés, par ailleurs, inégalitaires.L’opérationnalisation du principe de subsidiarité qui suppose l’existence d’une hiérarchie n’est pas sans paradoxe quand il concerne des organisations en quête de libération. Son étude souligne comment et dans quelles limites il autorise le développement du pouvoir d’agir en permettant d’organiser le travail autonome des salariés. En effet, le principe de subsidiarité ne joue pas une opposition frontale entre une autorité qui ne serait qu’autoritarisme et une liberté qui répugnerait à s’exercer dans un cadre. Au contraire, la subsidiarité, en tant que modalité d’exercice de l’autorité, rend possible la configuration d’une autonomie encadrée.Le principe de subsidiarité en ressort non seulement comme un principe de réalité permettant d’intégrer le lien de subordination qui caractérise le contrat de travail, mais aussi comme un principe de fonctionnement organisationnel considérant que le principal détenteur du pouvoir d’agir doit être situé en bas de l’échelle hiérarchique. Sous le prisme de la subsidiarité, la libération semble alors ne pas se situer dans la suppression d’une hiérarchie, dont le rôle, certes redéfini, reste affirmé comme essentiel, mais dans un pouvoir d’agir redonné aux salariés.