How far spatial accuracy governs land-use changes monitoring frequency: the urban sprawl monitoring example

International audienceIn this paper, we illustrate how far spatial accuracy of a land-use map governs land-use changes monitoring frequency on a urban sprawl monitoring case study. From a specific Monte Carlo approach propagating uncertainties, conf4idence curves for minimal monitoring frequency to detect significant changes in urban sprawl indicators were built. Results showed that frequency decreased when uspscaling indicators but it also showed very low monitoring frequency for indicators at the lower level. INTRODUCTION When setting up land-use monitoring systems, spatial uncertainties and their impact on the detection of indicator changes are usually ignored. To capture a significant change in land-use indicators is thus strongly related to its spatial resolution, the velocities of the process it represents and the accuracy of the used indicators. As a consequence, the required monitoring land-use change frequency, corresponding to the mimimum time step to ensure a significant change in indicators, also depends on these three factors: indicator spatial resolution, change process velocity and spatial indicator accuracy

Analyzing urban sprawl indicators under uncertainties

International audienceUrban sprawl causes the sealing of lands closest to the urban centers by transforming productive agricultural fields into impervious areas, with numerous economic, social and environmental impacts. Integrated monitoring is important to help urban policies and urban sprawl modelling, proposing urban sprawl indicators with combining spatial and social aspects of the phenomenon by spatial operators in GIS. For that, geographical information of sealing patches and territorial social data are used, but spatial uncertainties and their impact on the detection of indicator changes are usually ignored. The paper proposes (1) to evaluate uncertainties of indicator spatial and (2) to analyze the effect of upscaling on these uncertainties. The method used proposes to create impervious polygons according to their measured geometric and thematic uncertainties using a Monte Carlo simulation approach and to simulate social data according to census uncertainties. Impervious polygons are used in a closing operation, with different radius values, required to map morphological urban areas. The case study focused on three indicators (area, dispersion coefficient and population density) of the morphological urban areas for four administrative levels of administrative territorial units of Languedoc-Roussillon region, France. Results show that indicator uncertainties are generally higher for less densely populated areas than for the others at the finest territorial level, that the closing radius had a slightly influence on indicator uncertainties, and that uncertainties decreases with the upper territorial entities

Simulating geometric uncertainties of impervious areas based on image segmentation accuracy metrics

International audienceUrban sprawl monitoring is important for developing land management policies at various spatial scales. Segmentation and classification of satellite images allows obtaining polygons of impervious areas regularly over large areas, e.g. as has been implemented for the region Languedoc‐Roussillon in the south of France using 5 m RapidEye images. Starting from the results of this previous study, we aim to: i) evaluate the geometric and thematic accuracy of the impervious polygons (S) using segmentation accuracy metrics, and ii) use these metrics to simulate polygons having the same level of uncertainty. A manual segmentation (M) was used to evaluate the accuracy. After matching the polygons, the distance (d) and azimuth (a) of each vertex of M to the closest segment of the boundary of S was calculated. Spherically correlated random fields of d and a were used to randomly move the vertices of S. Realistic simulations of impervious polygons were obtained

Anchoring Secreted Proteins in Endoplasmic Reticulum by Plant Oleosin: The Example of Vitamin B12 Cellular Sequestration by Transcobalamin

BACKGROUND: Oleosin is a plant protein localized to lipid droplets and endoplasmic reticulum of plant cells. Our idea was to use it to target functional secretory proteins of interest to the cytosolic side of the endoplasmic reticulum of mammalian cells, through expressing oleosin-containing chimeras. We have designed this approach to create cellular models deficient in vitamin B12 (cobalamin) because of the known problematics associated to the obtainment of effective vitamin B12 deficient cell models. This was achieved by the overexpression of transcobalamin inside cells through anchoring to oleosin. METHODOLOGY: chimera gene constructs including transcobalamin-oleosin (TC-O), green fluorescent protein-transcobalamin-oleosin (GFP-TC-O) and oleosin-transcobalamin (O-TC) were inserted into pAcSG2 and pCDNA3 vectors for expression in sf9 insect cells, Caco2 (colon carcinoma), NIE-115 (mouse neuroblastoma), HEK (human embryonic kidney), COS-7 (Green Monkey SV40-transfected kidney fibroblasts) and CHO (Chinese hamster ovary cells). The subcellular localization, the changes in vitamin B12 binding activity and the metabolic consequences were investigated in both Caco2 and NIE-115 cells. PRINCIPAL FINDINGS: vitamin B12 binding was dramatically higher in TC-O than that in O-TC and wild type (WT). The expression of GFP-TC-O was observed in all cell lines and found to be co-localized with an ER-targeted red fluorescent protein and calreticulin of the endoplasmic reticulum in Caco2 and COS-7 cells. The overexpression of TC-O led to B12 deficiency, evidenced by impaired conversion of cyano-cobalamin to ado-cobalamin and methyl-cobalamin, decreased methionine synthase activity and reduced S-adenosyl methionine to S-adenosyl homocysteine ratio, as well as increases in homocysteine and methylmalonic acid concentration. CONCLUSIONS/SIGNIFICANCE: the heterologous expression of TC-O in mammalian cells can be used as an effective strategy for investigating the cellular consequences of vitamin B12 deficiency. More generally, expression of oleosin-anchored proteins could be an interesting tool in cell engineering for studying proteins of pharmacological interest

Rapport final de la Tâche 1 du Projet INCERDD « prise en compte des INCertitudes pour des Décisions Durables » - ANR Ville Durable: Définition d’objectifs partagés entre acteurs de la ville et identification d’un ensemble de stratégies relatives aux thématiques abordées en concertation avec les différents acteurs de la ville.

Cette tâche s’appuie sur l’application de méthodes issues du génie industriel à des problématiques urbaines pour caractériser la filière des acteurs concernés, révéler les besoins de ces derniers et mobiliser le(s) regard(s) complémentaire(s) de communautés de pratiques pour enrichir la lecture de l’environnement de l’objet d’étude. Concernant les incertitudes relatives à l’identification des alternatives de gestion, les travaux s’appuient d’abord sur l’identification de la filière des acteurs concernés par l’objet étudié (ex: élus et techniciens locaux, services déconcentrés de l’état, habitants, entreprises, associations, etc.) La mobilisation de l’expertise des acteurs et des panels de communauté de pratiques, notamment les usagers permet de construire une vision étendue de la “filière” des acteurs avec en perspective la destination finale du projet (les usages liés) et la prise en compte de son cycle de vie. Systématiquement, des acteurs clés ont été identifiés puis interviewés en vue d’appliquer le modèle RARe et la méthode Kano pour faire ressortir les besoins et les hiérarchiser. Au delà des besoins, une analyse plus complète de l'environnement des acteurs et du terrain étudié est réalisé sur la base d’un état de l’art et surtout la mobilisation de communauté de pratiques au sein de l’espace EMA (Environnement et Méthodologie d’Accélération) afin d’appréhender le plus largement possible la complexité des terrains. La diversité des besoins est mise en perspective avec les enjeux de la durabilité et les contraintes existantes. L’identification des stratégies est extrapolée de l’analyse des besoins adaptée au cas d’étude sélectionnés et du contexte global du terrain. Les résultats obtenus sont les suivants :•Concernant la problématique des réseaux, la dimension plus technique que stratégique a été bien mise en évidence. L’étude a été menée sur le territoire de la Communauté Urbaine du Grand Nancy. Les alternatives de gestion portent sur l’affectation des moyens globaux (lorsque ceux-ci sont disponibles) et de leur répartition entre inspection, maintenance et réhabilitation. •Concernant la problématique des inondations, l’étude a été menée sur le territoire de la commune de Dieulouard. Les alternatives de gestion retenues identifiées portent sur l’application du PPRI actuel, l’application d’une politique de réduction de la vulnérabilité existante, la réduction de l’aléa par la réalisation d’une digue.Cette approche issue du génie industriel nécessite d’être adaptée au contexte spécifique des problématiques de territoires pour lesquels la complexité, et donc les incertitudes dans le processus de décision, sont plus importantes. Ceci est notamment dû au fait que le territoire concentre des demandes multiples et des attentes parfois contradictoires. La confrontation des besoins permet de souligner les motivations ou objectifs potentiels à prendre en compte dans une stratégie de développement durable.A noter que la répétition et la confrontation du protocole scientifique proposé à la réalité des terrains ont permis d’affiner le mode opératoire quant à l’application de la démarche. Une partie du temps de la recherche et les expérimentation ont permis de constituer une communauté de praticien sur un champs d’application original tout en renforçant la robustesse de la méthode. Une approche complémentaire, non identifié au démarrage du projet consisterait à réinterroger le territoire du Grand Nancy sur la gestion globale de l’eau et du risque inondation à partir des résultats obtenus pour de territoire de Dieulouard. Une logique comparative entre deux territoires d’envergure différente permettrait d’affiner le modèle et d’intégrer plus finement les échelles possible d’intervention (taille du territoire, nombre des acteurs potentiellement concernés, processus de gouvernance impliqués, etc.) Au delà de l’apport pour les communautés de praticien, nos travaux participent d’une meilleure connaissance des acteurs, de leur intervention sur le territoire et de leur interdépendance sur la question de la gestion globale de l’eau. En France ce domaine est déjà largement étudié et décrit. Des rapports et ouvrages techniques sont disponibles pour les techniciens et décideurs. Une littérature et des dispositifs de vulgarisation générique sont également disponibles. Néanmoins, au niveau local, à l’échelle micro, la question de l’eau et des aléas qui lui sont liés peuvent rapidement faire l’objet d’une « ignorance », d’un oubli, comme les événements de la nuit du 21/22 mai 2012 l’ont montrés aux citoyens grand-nancéiens. Caractériser les besoins dans une visée durabilité autour de ces questions et phénomènes peut, non seulement, être un prétexte à un débat pédagogique et démocratique sur la gestion globale de l’eau auprès du, et entre, le plus grand nombre (citoyens, jeunes professionnels, experts aguerris, élus, etc.) et par capillarité heuristique, permettre de questionner et d’investiguer collectivement un certain nombre d’enjeux de société

New insights on the dynamic of the Vaucluse hydrological system from long base tiltmeter data

International audienc

New insight on the dynamic of the Fontaine de Vaucluse karst hydrosystem from tilt measurements

International audienceThe deformation of natural systems in response to subsurface water storage and redistribution provides insightsinto the main water flow path within heterogeneous systems, including the role of faults or fractures. A longbaseline tiltmeter was installed in the low-noise underground laboratory of Rustrel (LSBB) to study the responseof the Fontaine de Vaucluse (FDV) karst hydrosystem to water cycle. Tilt data and piezometric levels recorded in aborehole close to the LSBB show a strong correlation with the discharge of the system observed at the FDV spring30 km away. Over several months, tilt data were recorded on three base lines, thus allowing, for the first time,to study the tilt gradient variation that appears homogeneous. Such information provides a significant constrainton hydrological processes leading to the measured deformation. Several deformation models were tested usingthe ADELI code to estimate the type of hydro-mechanical structure that could reproduce the measured tilt andits gradient. On one hand, models show that uniform loading at the surface produces a much smaller signal thanobserved on measured data. On the other hand, the deformation related to the filling of a fracture following aprecipitation event requires unrealistic fracture size. Finally, we found that a suitable hydro-mechanical modelcorresponds to the loading of numerous fractures at the interface between the saturated and unsaturated zones. Sucha configuration predicts a tilt distribution in agreement with observations. This study suggests that tilt networksinto a karst system should provide key observation for deciphering hydrological processe

New insights on fractures deformation from tiltmeter data measured inside the Fontaine de Vaucluse karst system

International audienceTilt fluctuations can potentially reflect the response of hydrosystems to important rainfall. In this context, long baseline tiltmeters have been installed in an underground tunnel penetrating the Fontaine de Vaucluse karst to study the medium deformation related to solicitations exerted by water infiltrating the hydrosystem. The instruments monitor the tilt as well as its spatial variation. Northward tilts reaching a 1 μrad amplitude are observed consecutively to rainfalls. The tilt amplitude is highly correlated with the Fontaine de Vaucluse outlet flow fluctuations. The measured tilt signal is also relatively homogeneous over a 150 m length. Different types of structure likely to produce such observations are tested in order to identify their location with respect to the tiltmeters, their dimension as well as the amount of water level variation in the structure. Following rainfalls, the infiltration of water modifies the pore pressure, inducing a medium deformation. The hypothesis of an homogeneous surface loading on the Vaucluse plateau is first refuted since the related tilt is much lower than the one measured. The water supplied by rainfalls has to accumulate in discontinuities in order to generate a higher tilt. So, the deformation related to a pressure exerted on a fracture filled by water is assessed. A first study reveals the interest of the tilt homogeneity information that constrains strongly the fracture properties. Thus, the fracture must be located at a distance more than a few hundreds metres from the tiltmeters in order to produce a tilt homogeneous in space. If the fracture is initially dry, it must also be filled on a height higher than 150 m consecutive to a rainfall in order to generate a tilt amplitude in the same magnitude as the one measured. Then, we explore the influence of water level variations on the tilt produced by a fracture located at the interface between the saturated and unsaturated zones, which are thereby permanently flooded. Since several parameters of that model satisfactorily explain the field observations, we discuss how simultaneous geodetical observations could provide complementary information that would further constrain the geometry of the structure at the origin of the medium deformation