Chiral signatures of herbicides and metabolites concentrations as tools to characterize the hydrodynamic of aquifer

International audienc

Caractérisation sur site de matrices contaminées par des composés volatils : teneur totale et première estimation de la mobilité

International audienceThe urban sprawl, pushes to the regeneration of brownfield sites located nearby cities. These old industrial areas of degraded and abandoned land are found today in the heart of cities and their requalification becomes key factor of urban development (RESCUE, 2005).This leads to a need for characterizing the soil and its pollution. However today, the mobility has to be evaluate (transfer) and therefore the risks of damage to targets beyond the total amount of pollutant (definition of the source of pollution). In this study, the aim is to better assess the impact on human health considering soil gas and groundwater.The field devices often are less reliable than laboratory equipment; however they offer the opportunity to multiply analysis on site, significantly increasing the representativeness of the site characterization. The GC used (HAPSITE) allows on site compound identification at concentration from ppt to ppm depending on the compound and the matrix considered.The use of this portable GC has demonstrated its ability to obtain on-site an initial identification of compounds that are not included in the usual analytical packages. This allows to adapt on site the analyses to be performed (case of an incomplete history of the site).In the case of volatile compounds, quick analyses after the sampling, allow to limit the risk of losses.To evaluate the mobility toward the gas phase, first tests were carried out from soil and water, by varying the head space (volume of the medium relative to the degassing volume) and heating temperature. To evaluate the mobility toward the water phase, extractions with water and with methanol were performed.The first results are encouraging but it remains to consolidate the protocols to make them robust (usable and transferable to all soil types).This project has received financial support of ADEME.La politique d’étalement des villes, aujourd’hui remise en cause, pousse à la réhabilitation des friches industrielles implantées à proximité des villes. Ces anciennes zones d’activités industrielles aujourd’hui dégradées et abandonnées se retrouvent actuellement au cœur de centres villes et leurs requalifications et réintégrations deviennent des facteurs clés d’aménagement urbain (RESCUE, 2005).Cela amène à un besoin de caractérisation de la matrice sol et de son contenu en polluant. Cependant aujourd’hui au-delà de la teneur totale en polluant (définition de la source de pollution), c’est davantage sa mobilité que l’on souhaite évaluer (transfert) et par là les risques d’atteinte de cibles. L’objectif ici est de mieux évaluer l‘impact sur la santé humaine en considérant aussi les gaz du sol et les eaux souterraines.Les appareils de terrain ont souvent une fiabilité plus faible que les appareils de laboratoire, cependant ils offrent l’opportunité de multiplier les analyses sur site, ce qui augmente significativement la représentativité des caractérisations de sites. La GC utilisée (HAPSITE) permet d’identifier des composés situés dans un domaine allant du ppt au ppm selon les composés et les matrices considérés.L’utilisation de la GC portable a démontré sa capacité à obtenir sur site une première identification des composés en présence dont certains ne sont pas inclus dans les packs analytiques proposés par les laboratoires permettant ainsi de réajuster les analyses à réaliser (atout en cas d’un historique de site incomplet).Dans le cas des composés volatils, la mesure au plus près du prélèvement, permet en outre de s’affranchir des risques de pertes.Pour évaluer la mobilité vers la phase gaz, des premiers essais ont été réalisés depuis des matrices sol et eau, en faisant varier l’espace de tête disponible (volume de la matrice par rapport au volume de dégazage) et la température. Pour évaluer la mobilité vers la phase eau, des extractions à l’eau et avec du méthanol ont été réalisées.Les premiers résultats sont encourageants mais il reste à consolider les protocoles afin de les rendre robustes (utilisables et transférables à tous types de sols).Ce projet a bénéficié d’un soutien financier de l’ADEME

Heisenberg Symmetry and Collective Modes of One Dimensional Unitary Correlated Fermions

The correlated fermionic many-particle system, near infinite scattering length, reveals an underlying Heisenberg symmetry in one dimension, as compared to an $SO(2,1)$ symmetry in two dimensions. This facilitates an exact map from the interacting to the non-interacting system, both with and without a harmonic trap, and explains the short-distance scaling behavior of the wave-function. Taking advantage of the phenomenological Calogero-Sutherland-type interaction, motivated by the density functional approach, we connect the ground-state energy shift, to many-body correlation effect. For the excited states, modes at integral values of the harmonic frequency $\omega$, are predicted in one dimension, in contrast to the breathing modes with frequency $2\omega$ in two dimensions.Comment: 5 pages, revamped version for clarit

Efficient three-dimensional reconstruction of aquatic vegetation geometry: Estimating morphological parameters influencing hydrodynamic drag

Aquatic vegetation can shelter coastlines from energetic waves and tidal currents, sometimes enabling accretion of fine sediments. Simulation of flow and sediment transport within submerged canopies requires quantification of vegetation geometry. However, field surveys used to determine vegetation geometry can be limited by the time required to obtain conventional caliper and ruler measurements. Building on recent progress in photogrammetry and computer vision, we present a method for reconstructing three-dimensional canopy geometry. The method was used to survey a dense canopy of aerial mangrove roots, called pneumatophores, in Vietnam’s Mekong River Delta. Photogrammetric estimation of geometry required 1) taking numerous photographs at low tide from multiple viewpoints around 1 m2 quadrats, 2) computing relative camera locations and orientations by triangulation of key features present in multiple images and reconstructing a dense 3D point cloud, and 3) extracting pneumatophore locations and diameters from the point cloud data. Step 3) was accomplished by a new ‘sector-slice’ algorithm, yielding geometric parameters every 5 mm along a vertical profile. Photogrammetric analysis was compared with manual caliper measurements. In all 5 quadrats considered, agreement was found between manual and photogrammetric estimates of stem number, and of number × mean diameter, which is a key parameter appearing in hydrodynamic models. In two quadrats, pneumatophores were encrusted with numerous barnacles, generating a complex geometry not resolved by hand measurements. In remaining cases, moderate agreement between manual and photogrammetric estimates of stem diameter and solid volume fraction was found. By substantially reducing measurement time in the field while capturing in greater detail the 3D structure, photogrammetry has potential to improve input to hydrodynamic models, particularly for simulations of flow through large-scale, heterogenous canopies

Efficiency and effectiveness evaluation of an automated multi-country patient count cohort system

International audienceBackgroundWith the increase of clinical trial costs during the last decades, the design of feasibility studies has become an essential process to reduce avoidable and costly protocol amendments. This design includes timelines, targeted sites and budget, together with a list of eligibility criteria that potential participants need to match.The present work was designed to assess the value of obtaining potential study participant counts using an automated patient count cohort system for large multi-country and multi-site trials: the Electronic Health Records for Clinical Research (EHR4CR) system.MethodsThe evaluation focuses on the accuracy of the patient counts and the time invested to obtain these using the EHR4CR platform compared to the current questionnaire based process. This evaluation will assess the patient counts from ten clinical trials at two different sites. In order to assess the accuracy of the results, the numbers obtained following the two processes need to be compared to a baseline number, the “alloyed” gold standard, which was produced by a manual check of patient records.ResultsThe patient counts obtained using the EHR4CR system were in three evaluated trials more accurate than the ones obtained following the current process whereas in six other trials the current process counts were more accurate. In two of the trials both of the processes had counts within the gold standard’s confidence interval.In terms of efficiency the EHR4CR protocol feasibility system proved to save approximately seven calendar days in the process of obtaining patient counts compared to the current manual process.ConclusionsAt the current stage, electronic health record data sources need to be enhanced with better structured data so that these can be re-used for research purposes. With this kind of data, systems such as the EHR4CR are able to provide accurate objective patient counts in a more efficient way than the current methods.Additional research using both structured and unstructured data search technology is needed to assess the value of unstructured data and to compare the amount of efforts needed for data preparation

MONIC - MONItoring des gaz et des Contaminants organiques de sites pollués en cours de remédiation

National audienc