Organisation et rôle de la profession agricole dans le développement des systèmes irrigués : quelques enseignements tirés du cas de l'Office du Niger au Mali

Cette communication traite du rôle des organisations paysannes dans le développement agricole au Mali et en particulier pour la zone de l'Office du Niger. Les politiques d'ajustement, puis maintenant de post-ajustement, donnent un rôle croissant aux organisations paysannes dans divers cadres de concertation où doivent se négocier les politiques sectorielles et se cogérer les filières agricoles. A travers le cas du Mali et plus particulièrement de la zone irriguée de l'Office du Niger (mais aussi de la filière coton), il est mis en en balance les nouveaux enjeux auxquels se trouvent confrontées les organisations de producteurs - extension du domaine aménagé, gestion du périmètre irrigué, amélioration de la productivité - et leurs capacités à les relever, capacités qui sont fortement liées aux diverses conditions de leur émergence. (Résumé d'auteur

Totally laparoscopic aortic repair: A new device for direct transperitoneal approach

On the basis of our experience with more than 71 cases of totally laparoscopic aortic surgery by the retrocolic approach, we have developed a new technique by a simple transperitoneal approach. The purpose of this report is to describe that technique and the novel laparoscopic bowel retractor used to ensure stable exposure of the aorta

Les organisations de producteurs en zone cotonnière au Mali

En Afrique de l’Ouest, les politiques de post ajustement donnent un rôle croissant aux organisations paysannes dans divers cadres de concertation où doivent se négocier les politiques sectorielles et se cogérer les filières agricoles. À travers le cas la filière coton au Mali, qui concerne près du quart de la population et un peu moins de 10 % du PIB, il est mis en balance les nouveaux enjeux auxquels se trouvent confrontées les organisations de producteurs et leurs capacités à les relever, capacités qui sont fortement liées aux diverses conditions de leur émergence. Les OP soit sont initiées par les pouvoirs publics (l’État ou la société cotonnière) soit émergent de la société civile à l’initiative des paysans ou d’Ong. La perspective d’une gestion interprofessionnelle de la filière coton en cours de privatisation permet de discuter des options offertes et de leurs implications en termes de règlementation, d’appuis et de recherches.In West Africa, post adjustment policies give an increasing role to farmers organizations within various concertation frameworks for the negotiation of sectoral policies and joint management of agricultural chains. Through the Malian cotton chain case which concerns about one quarter of the population and a little less than 10% of the GDP, the new challenges encountered by farmers’ organizations are confronted with their ability to face them. Thisability is strongly related to the various conditions of their emergence. Farmers’ organizations have been initiated by authorities (State or cotton Company) or have emerged from the civil society, initiated by peasants or Ngos. The prospect for an interprofessional management of the cotton chain under privatization allows the discussion of options offered and of their consequences for regulation, supports and research

The specific surface area and chemical composition of diamond dust near Barrow, Alaska

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95687/1/jgrd17349.pd

Towards IASI-New Generation (IASI-NG): impact of improved spectral resolution and radiometric noise on the retrieval of thermodynamic, chemistry and climate variables

Besides their strong contribution to weather forecast improvement through data assimilation, thermal infrared sounders onboard polar-orbiting platforms are now playing a key role for monitoring atmospheric composition changes. The Infrared Atmospheric Sounding Interferometer (IASI) instrument developed by the French space agency (CNES) and launched by Eumetsat onboard the Metop satellite series is providing essential inputs for weather forecasting and pollution/climate monitoring owing to its smart combination of large horizontal swath, good spectral resolution and high radiometric performance. EUMETSAT is currently preparing the next polar-orbiting program (EPS-SG) with the Metop-SG satellite series that should be launched around 2020. In this framework, CNES is studying the concept of a new instrument, the IASI-New Generation (IASI-NG), characterized by an improvement of both spectral and radiometric characteristics as compared to IASI, with three objectives: (i) continuity of the IASI/Metop series; (ii) improvement of vertical resolution; (iii) improvement of the accuracy and detection threshold for atmospheric and surface components. In this paper, we show that an improvement of spectral resolution and radiometric noise fulfill these objectives by leading to (i) a better vertical coverage in the lower part of the troposphere, thanks to the increase in spectral resolution; (ii) an increase in the accuracy of the retrieval of several thermodynamic, climate and chemistry variables, thanks to the improved signal-to-noise ratio as well as less interferences between the signatures of the absorbing species in the measured radiances. The detection limit of several atmospheric species is also improved. We conclude that IASI-NG has the potential for strongly benefiting the numerical weather prediction, chemistry and climate communities now connected through the European GMES/Copernicus initiative

Technical Note: New ground-based FTIR measurements at Ile de La Réunion: observations, error analysis, and comparisons with independent data

Ground-based high spectral resolution Fourier-transform infrared (FTIR) solar absorption spectroscopy is a powerful remote sensing technique to obtain information on the total column abundances and on the vertical distribution of various constituents in the atmosphere. This work presents results from two FTIR measurement campaigns in 2002 and 2004, held at Ile de La Réunion (21° S, 55° E). These campaigns represent the first FTIR observations carried out at a southern (sub)tropical site. They serve the initiation of regular, long-term FTIR monitoring at this site in the near future. To demonstrate the capabilities of the FTIR measurements at this location for tropospheric and stratospheric monitoring, a detailed report is given on the retrieval strategy, information content and corresponding full error budget evaluation for ozone (O3), methane (CH4), nitrous oxide (N2O), carbon monoxide (CO), ethane (C2H6), hydrogen chloride (HCl), hydrogen fluoride (HF) and nitric acid (HNO3) total and partial column retrievals. Moreover, we have made a thorough comparison of the capabilities at sea level altitude (St.-Denis) and at 2200 m a.s.l. (Maïdo). It is proved that the performances of the technique are such that the atmospheric variability can be observed, at both locations and in distinct altitude layers. Comparisons with literature and with correlative data from ozone sonde and satellite (i.e., ACE-FTS, HALOE and MOPITT) measurements are given to confirm the results. Despite the short time series available at present, we have been able to detect the seasonal variation of CO in the biomass burning season, as well as the impact of particular biomass burning events in Africa and Madagascar on the atmospheric composition above Ile de La Réunion. We also show that differential measurements between St.-Denis and Maïdo provide useful information about the concentrations in the boundary layer.Peer reviewe

The performance of the ATHENA X-ray Integral Field Unit

The X-ray Integral Field Unit (X-IFU) is a next generation microcalorimeter planned for launch onboard the Athena observatory. Operating a matrix of 3840 superconducting Transition Edge Sensors at 90 mK, it will provide unprecedented spectro-imaging capabilities (2.5 eV resolution, for a field of view of 5') in the soft X-ray band (0.2 up to 12 keV), enabling breakthrough science. The definition of the instrument evolved along the phase A study and we present here an overview of its predicted performances and their modeling, illustrating how the design of the X-IFU meets its top-level scientific requirements. This article notably covers the energy resolution, count-rate capability, quantum efficiency and non X-ray background levels, highlighting their main drivers

The Athena X-ray Integral Field Unit: a consolidated design for the system requirement review of the preliminary definition phase

The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer, studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory, a versatile observatory designed to address the Hot and Energetic Universe science theme, selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), it aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over an hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR, browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters. Finally we briefly discuss on the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, and touch on communication and outreach activities, the consortium organisation, and finally on the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained. (abridged).Comment: 48 pages, 29 figures, Accepted for publication in Experimental Astronomy with minor editin

The Athena X-ray Integral Field Unit: a consolidated design for the system requirement review of the preliminary definition phase

The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory. Athena is a versatile observatory designed to address the Hot and Energetic Universe science theme, as selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), X-IFU aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over a hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR (i.e. in the course of its preliminary definition phase, so-called B1), browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters, such as the instrument efficiency, spectral resolution, energy scale knowledge, count rate capability, non X-ray background and target of opportunity efficiency. Finally, we briefly discuss the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, touch on communication and outreach activities, the consortium organisation and the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained. The X-IFU will be provided by an international consortium led by France, The Netherlands and Italy, with ESA member state contributions from Belgium, Czech Republic, Finland, Germany, Poland, Spain, Switzerland, with additional contributions from the United States and Japan.The French contribution to X-IFU is funded by CNES, CNRS and CEA. This work has been also supported by ASI (Italian Space Agency) through the Contract 2019-27-HH.0, and by the ESA (European Space Agency) Core Technology Program (CTP) Contract No. 4000114932/15/NL/BW and the AREMBES - ESA CTP No.4000116655/16/NL/BW. This publication is part of grant RTI2018-096686-B-C21 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”. This publication is part of grant RTI2018-096686-B-C21 and PID2020-115325GB-C31 funded by MCIN/AEI/10.13039/501100011033

Étude électrochimique et électrohydrodynamique du régime permanent de l’injection unipolaire de protons dans le nitrobenzène

Une injection de protons provenant de l’oxydation de l’eau résiduelle est obtenue dans du nitrobenzène sous l’influence d’un champ électrique élevé. Les impuretés électrolytiques sont éliminées par circulation du liquide dans une cellule d’électrodialyse, de ce fait le courant des espèces dissociées est négligeable devant le courant d’injection.L’injection provoque un fort effet de pompe ionique. La valeur de la pression mesurée est en accord avec celle qui est calculée à partir de la répartition du champ électrique donnée par l’effet Kerr. La densité volumique des porteurs est uniforme dans l'espace injecteur-collecleur. La vitesse des porteurs augmentée par les mouvements turbulents du liquide augmente avec la densité volumique, mais la « mobilité électrohydrodynamique moyenne » tend vers la mobilité vraie lorsque la densité volumique tend vers zéro.Le comportement de deux injecteurs différents : membrane cationique, platine poli est étudié. Le comportement d’un injecteur en platine devient reproductible après un conditionnement qui consiste en une émission prolongée sous champ intense. Le courant d’injection stationnaire dépend de la teneur en eau, il est nul lorsque la teneur en eau est inférieure a 300 mg/1, il peut être limité par l’émission ou limité par la charge d’espace. Il est 1 000 fois plus faible que le courant limité par la diffusion comme en polarographie avec un électrolyte support