Toward a Harmonization for Using in situ Nutrient Sensors in the Marine Environment

Improvedcomparabilityofnutrientconcentrationsinseawaterisrequiredtoenhancethe quality and utility of measurements reported to global databases. Significant progress has been made over recent decades in improving the analysis and data quality for traditional laboratory measurements of nutrients. Similar efforts are required to establish high-quality data outputs from in situ nutrient sensors, which are rapidly becoming integral components of ocean observing systems. This paper suggests using the good practices routine established for laboratory reference methods to propose a harmonized setofdeploymentprotocolsandofqualitycontrolproceduresfornutrientmeasurements obtained from in situ sensors. These procedures are intended to establish a framework to standardize the technical and analytical controls carried out on the three main types of in situ nutrient sensors currently available (wet chemical analyzers, ultraviolet optical sensors, electrochemical sensors) for their deployments on all kinds of platform. The routine reference controls that can be applied to the sensors are listed for each step of sensor use: initial qualification under controlled conditions in the laboratory, preparation of the sensor before deployment, field deployment and finally the sensor recovery. The fundamental principles applied to the laboratory reference method are then reviewed in termsofthecalibrationprotocol,instrumentalinterferences,environmentalinterferences, external controls, and method performance assessment. Data corrections (linearity, sensitivity, drifts, interferences and outliers) are finally identified along with the concepts and calculations for qualification for both real time and time delayed data. This paper emphasizes the necessity of future collaborations between research groups, referenceaccredited laboratories, and technology developers, to maintain comparability of the concentrationsreportedforthevariousnutrientparametersmeasuredbyinsitusensors

On morphological hierarchical representations for image processing and spatial data clustering

Hierarchical data representations in the context of classi cation and data clustering were put forward during the fties. Recently, hierarchical image representations have gained renewed interest for segmentation purposes. In this paper, we briefly survey fundamental results on hierarchical clustering and then detail recent paradigms developed for the hierarchical representation of images in the framework of mathematical morphology: constrained connectivity and ultrametric watersheds. Constrained connectivity can be viewed as a way to constrain an initial hierarchy in such a way that a set of desired constraints are satis ed. The framework of ultrametric watersheds provides a generic scheme for computing any hierarchical connected clustering, in particular when such a hierarchy is constrained. The suitability of this framework for solving practical problems is illustrated with applications in remote sensing

Les Pédo-paysages des plaines centrales de Midi-Pyrénées

Les sols des zones de plaines de la région Midi-Pyrénées montrent une grande diversité liée, notamment, au carrefour des influences climatiques passées et actuelles : glaciaire, méditerranéenne et atlantique. Le présent article illustre la distribution des principales Unités Typologiques de Sols parmi les Unités pédo-paysagères dans les zones de plaines depuis le nord du Lot jusqu'au piémont ariégeois. La couverture pédologique y est très marquée par la nature des grands ensembles sédimentaires, depuis les contreforts du Massif central, jusqu'à la Molasse argilo-calcaire très largement étendue dans le bassin toulousain

On the equivalence between hierarchical segmentations and ultrametric watersheds

We study hierarchical segmentation in the framework of edge-weighted graphs. We define ultrametric watersheds as topological watersheds null on the minima. We prove that there exists a bijection between the set of ultrametric watersheds and the set of hierarchical segmentations. We end this paper by showing how to use the proposed framework in practice in the example of constrained connectivity; in particular it allows to compute such a hierarchy following a classical watershed-based morphological scheme, which provides an efficient algorithm to compute the whole hierarchy.Comment: 19 pages, double-colum

Large-scale unit commitment under uncertainty: an updated literature survey

The Unit Commitment problem in energy management aims at finding the optimal production schedule of a set of generation units, while meeting various system-wide constraints. It has always been a large-scale, non-convex, difficult problem, especially in view of the fact that, due to operational requirements, it has to be solved in an unreasonably small time for its size. Recently, growing renewable energy shares have strongly increased the level of uncertainty in the system, making the (ideal) Unit Commitment model a large-scale, non-convex and uncertain (stochastic, robust, chance-constrained) program. We provide a survey of the literature on methods for the Uncertain Unit Commitment problem, in all its variants. We start with a review of the main contributions on solution methods for the deterministic versions of the problem, focussing on those based on mathematical programming techniques that are more relevant for the uncertain versions of the problem. We then present and categorize the approaches to the latter, while providing entry points to the relevant literature on optimization under uncertainty. This is an updated version of the paper "Large-scale Unit Commitment under uncertainty: a literature survey" that appeared in 4OR 13(2), 115--171 (2015); this version has over 170 more citations, most of which appeared in the last three years, proving how fast the literature on uncertain Unit Commitment evolves, and therefore the interest in this subject

Les pièges à particules : principes, état de l'art et perspectives pour la surveillance des milieux aquatiques - focus sur les cours d'eaux

[Departement_IRSTEA]Eaux [TR1_IRSTEA]BELCA [ADD1_IRSTEA]Systèmes aquatiques soumis à des pressions multiples [Relecteur_IRSTEA]Yari, A. ; Ghestem, J.P.Particulate matters are a central point in the assessment of water bodies. A wide range of techniques is available for sampling of particulate matters (TSS / Sediment) in aquatic systems. The relevance of each technique is determined by the flows and dynamics of the particulate matters, the data requirements (limit of quantification, accuracy, uncertainty, representativity ...) and available resources. These factors determine the sampling strategy and method to be adopted and how the sample should be handled (transported and stored) after collection. It is therefore essential to pay particular attention to the following question: Which sampling approach (s) will provide the most representative sample? Sediment traps are collectors, boxes, or baskets, placed in the water column and which capture the particulate matters continuously by decantation. Once deployed, the water passes through the system in which a decrease in the velocity of the flow occurs, causing the particulate matters to decant in the tool. The objective of this action is to evaluate the potential of sediment traps in the monitoring of chemical contamination of aquatic environments. The main observations show that sediment traps can be integrated into strategies for the chemical monitoring of aquatic environments' contamination, in particular to: - Integrate the variability of contaminant concentrations in particulate matter; - Track chemical contamination of water bodies; - Improve the representativeness of the assessment of chemical contamination of aquatic environments by an integrated measure, in addition to integrative samplers; - Meet chemical monitoring requirements for EQS and whole water; in addition to passive integrative samplers; - Estimate flows of particulate contaminants.La prise en compte des particules est un point central de l'évaluation des masses d'eaux. Un large éventail de techniques est disponible pour l'échantillonnage des particules (MES/Sédiments) dans les systèmes aquatiques. La pertinence de chaque technique est déterminée par les flux et dynamiques des particules, les exigences sur les données (limite de quantification, exactitude, incertitude, représentativité, ...) et les ressources disponibles. Ces facteurs déterminent la méthode d'échantillonnage à adopter et la manière dont l'échantillon devra être manipulé (transporté et stocké) après la collecte. Il est donc indispensable de porter une attention particulière à la question suivante : quelle(s) approche(s) d'échantillonnage fournira (ont) 'échantillon le plus représentatif ? Les pièges à particules sont des collecteurs, boîtes, ou paniers, placés dans la colonne d'eau et qui capturent les particules en continu par décantation. Une fois déployé, l'eau passe au travers du système au sein duquel une diminution de la vitesse du débit s'opère, provoquant la décantation des particules dans l'outil. L'objectif de cette action est d'évaluer le potentiel des pièges à particules dans le cadre de la surveillance de la contamination chimique des milieux aquatiques. Les principales observations démontrent que les pièges à particules peuvent être intégrés dans des stratégies de surveillance de la contamination chimique des milieux aquatiques, notamment pour : - Intégrer la variabilité des concentrations en contaminants dans les particules; - Suivre en tendance la contamination chimique des masses d'eau ; - Améliorer la représentativité de l'évaluation de la contamination chimique des milieux aquatiques par une mesure intégrée, en complément d'échantillonneurs intégratifs ; - Répondre aux exigences de surveillance de l'état chimique NQE et fraction eau totale ; en complément d'échantillonneurs intégratifs passifs ; - Estimer des flux de contaminants particulaire

Isolated cell walls exhibit cation binding properties distinct from those of plant roots

International audienceThe principal contributor to the cation binding properties of roots is currently considered to be the cell wall or, alternatively, the plasma membrane. The aim of this study was to highlight their respective contributions in the binding properties. Cell walls of a dicotyledon (Solanum lycopersicum L.) and monocotyledon (Triticum aestivum L.) were isolated from roots and their binding properties were compared to those of their respective roots. Cell wall and root binding capacities were evaluated by potentiometric titrations and cation exchange capacity measurements, while their biochemical composition was analyzed by C-13-NMR spectroscopy. The lower binding capacity of isolated cell walls compared to roots revealed that cell plasma membranes had a higher binding site density than cell walls. The significant decrease in some NMR signals, i.e. carbonyl C, N alkyl/methoxyl C and alkyl C regions, suggested that carboxyl, amine and phosphate binding sites, borne by proteins and phospholipid plasma membranes, contribute to the binding capacity. Cell walls and plasma membranes were found to be jointly involved in root binding properties and their respective contributions seemed vary between plants