Warm and fertile sub-humid conditions enhance litterfall to sustain high soil respiration fluxes in a mediterranean cork oak forest

Soil respiration is a major component of the global carbon budget and Mediterranean ecosystems have usually been studied in locations with shallow soils, mild temperatures, and a prolonged dry season. This study investigates seasonal soil respiration rates and underlying mechanisms under wetter, warmer, and more fertile conditions in a Mediterranean cork oak forest of Northern Tunisia (Africa), acknowledged as one of the most productive forests in the Mediterranean basin. We applied a soil respiration model based on soil temperature and relative water content and investigated how ecosystem functioning under these favorable conditions affected soil carbon storage through carbon inputs to the soil litter. Annual soil respiration rates varied between 1774 gC m(-2) year(-1) and 2227 gC m(-2) year(-1), which is on the highest range of observations under Mediterranean climate conditions. We attributed this high soil carbon flux as a response to favorable temperatures and soil water content, but this could be sustained only by a small carbon allocation to roots (root/shoot ratio = 0.31-0.41) leading to a large allocation to leaves with a multiannual leaf production, enhanced annual twig elongation (11.5-28.5 cm) with a reduced leaf life span (<1 year) maintaining a low LAI (1.68-1.88) and generating a high litterfall (386-636 gC m(-2) year(-1)). Thus, the favorable climatic and edaphic conditions experienced by these Mediterranean cork oak forests drove high soil respiration fluxes which balanced the high carbon assimilation leading to a relatively small overall contribution (10.96-14.79 kgC m(-2)) to soil carbon storage

Analysis of soil texture using terrasar x-band sar

International audienceIn this paper, it is proposed to use TERRASAR-X data for analysis and estimation of soil surface texture. Our study is based on experimental campaigns carried out over a semi-arid area in North Africa. Simultaneously to TERRASAR-X radar acquisitions, ground measurements (texture, soil moisture and roughness) were made on different test fields. A strong correlation is observed between soil texture and a processed signal from two radar images, the first acquired just after a rain event and the second corresponding to dry soil conditions, acquired three weeks later. An empirical relationship is proposed for the retrieval from radar signals of clay content percent. Soil texture mapping is proposed over the study site, which includes bare soils and olive groves

Irrigated grassland monitoring using a time series of terraSAR-X and COSMO-skyMed X-Band SAR Data

[Departement_IRSTEA]Territoires [TR1_IRSTEA]SYNERGIE [Axe_IRSTEA]TETIS-ATTOSInternational audienceThe objective of this study was to analyze the sensitivity of radar signals in the X-band in irrigated grassland conditions. The backscattered radar signals were analyzed according to soil moisture and vegetation parameters using linear regression models. A time series of radar (TerraSAR-X and COSMO-SkyMed) and optical (SPOT and LANDSAT) images was acquired at a high temporal frequency in 2013 over a small agricultural region in southeastern France. Ground measurements were conducted simultaneously with the satellite data acquisitions during several grassland growing cycles to monitor the evolution of the soil and vegetation characteristics. The comparison between the Normalized Difference Vegetation Index (NDVI) computed from optical images and the in situ Leaf Area Index (LAI) showed a logarithmic relationship with a greater scattering for the dates corresponding to vegetation well developed before the harvest. The correlation between the NDVI and the vegetation parameters (LAI, vegetation height, biomass, and vegetation water content) was high at the beginning of the growth cycle. This correlation became insensitive at a certain threshold corresponding to high vegetation (LAI ~2.5 m2/m2). Results showed that the radar signal depends on variations in soil moisture, with a higher sensitivity to soil moisture for biomass lower than 1 kg/m². HH and HV polarizations had approximately similar sensitivities to soil moisture. The penetration depth of the radar wave in the X-band was high, even for dense and high vegetation; flooded areas were visible in the images with higher detection potential in HH polarization than in HV polarization, even for vegetation heights reaching 1 m. Lower sensitivity was observed at the X-band between the radar signal and the vegetation parameters with very limited potential of the X-band to monitor grassland growth. These results showed that it is possible to track gravity irrigation and soil moisture variations from SAR X-band images acquired at high spatial resolution (an incidence angle near 30°)

Valeur de l’examen extemporane en pathologie thyroïdienne

OBJECTIF : Etudier la valeur de l’examen extemporané dans la pathologie thyroidienne et identifier ses limitesMATERIELS ET METHODES : Notre étude est rétrospective incluant 800 examens extemporanés réalisés sur des pièces de résectionthyroïdienne colligés dans notre service sur une période de 12 ans (2000-2011).Les résultats ont été comparés à ceux del’examen anatomopathologique définitif.RESULTATS : Les résultats étaient concordants dans 96,5%, discordants dans 3,5 %. La sensibilité de l’examen extemporané toustypes confondus était de 78 % et la spécificité de 100 %CONCLUSION : Notre étude a montré une spécificité parfaite de l’examen extemporané cependant l’interprétation difficile des lésionsthyroïdiennes d’architecture vésiculaire expliquent une sensibilité de 78 %.Mots Clés : Thyroïdectomie, examen extemporanOBJECTIVE: To assess the value of frozen-section examination in thyroid surgery and evaluate its limitationsPATIENTS AND METHODES: This retrospective study examined the results of 800 frozen-sections of thyroid specimens analysedover the 12 –year period (2000-2011). Their results were compared with definitive anatomo-pathological examinationRESULTS :Frozen-section diagnosis was concordant with subsequent histopathological examination in 96,5% ,discordant in 3,5%.The global specificity of frozen section analysis for all histological subtypes was 100 % and its sensitivity was 78 %.CONCLUSION: This study shows the good specificity of frozen section .Discordances between frozen-section and definitive diagnosiswas associated with microfllicular lesions wich explain the sensibility of 78%Key Words: Thyroid surgery, frozen section examinatio

Soil moisture active and passive microwave products: intercomparison and evaluation over a Sahelian site

This paper presents a comparison and an evaluation of five soil moisture products based on satellite-based passive and active microwave measurements. Products are evaluated for 2005&amp;ndash;2006 against ground measurements obtained from the soil moisture network deployed in Mali (Sahel) in the framework of the African Monsoon Multidisciplinary Analysis project. It is shown that the accuracy of the soil moisture products is sensitive to the retrieval approach as well as to the sensor type (active or passive) and to the signal frequency (from 5.6 GHz to 18.8 GHz). The spatial patterns of surface soil moisture are compared between the different products at meso-scale (14.5&amp;deg; N&amp;ndash;17.5&amp;deg; N and 2&amp;deg; W&amp;ndash;1&amp;deg; W). A general good consistency between the different satellite soil moisture products is shown in terms of meso-scale spatial distribution, in particular after convective rainfall occurrences. Comparison to ground measurement shows that although soil moisture products obtained from satellite generally over-estimate soil moisture values during the dry season, most of them capture soil moisture temporal variations in good agreement with ground station measurements

Soil texture estimation over a semiarid area using TerraSAR-X radar data

In this letter, it is proposed to use TerraSAR-X data for analysis and estimation of soil surface texture. Our study is based on experimental campaigns carried out over a semiarid area in North Africa. Simultaneously with TerraSAR-X radar acquisitions, ground measurements (texture, soil moisture, and roughness) were made on different test fields. A strong correlation is observed between soil texture and a processed signal from two radar images, with the first acquired just after a rain event and the second corresponding to dry soil conditions, acquired three weeks later. An empirical relationship is proposed for the retrieval from radar signals of clay content percent. Soil texture mapping is proposed over the study site, which includes bare soils and olive groves

Tumeur neuro-ectodermique primitive du rein avec insuffisance rénale

Introduction : Les Tumeurs neuroectodermiques périphériques (PNET) ou le sarcome d'Ewing est un cancer qui se développe habituellement dans les os et la localisation extrasquelettique est rare. Les PNET de localisation rénale sont rares et se caractérisent par une évolution clinique agressive et un mauvais pronostic. Seuls quelques cas de PNET rénaux avec insuffisance rénale ont été rapportés dans la littérature à ce jour.  Cas clinique : Nous présentons un cas de PNET rénal chez un homme de 48 ans sans antécédents médicaux, qui présentait une douleur au flanc droit, imitant des coliques nephretiques. Une échographie abdominale a montré une masse rénale droite.  La tomodensitométrie a montré une masse du rein droit de 23x9 cm associée à une carcinose péritonéale, la tumeur été localement avancé avec invasion vasculaire et des structures adjacentes. L'analyse histologique a trouvé de petites cellules rondes monomorphes qui forment des rosettes. à l’immunohistochimie, les cellules tumorales sont fortement positifs pour le CD99 et la vimentine confirmant le diagnostic de PNET. Le patient a développé une insuffisance rénale au début de l'évolution de la maladie qui nous a empêchés de réaliser le bilan d’extension de la maladie et de prescrire une chimiothérapie. Le patient est décédé de sa maladie trois mois plus tard.Discussion : Les Tumeur neuroectodermique périphérique (PNET) de localisation rénale surviennent généralement pendant l'enfance, l'adolescence ou chez le jeune adulte ce qui n’est pas le cas de notre patient (48 ans). L’insuffisance rénale en association avec les PNET rénaux a été rapportée précédemment dans seulement quelques cas pédiatriques, mais pas dans la population adulte. cette insuffisance rénale peut être expliquer par: d'une part le thrombus direct qui envahit la veine rénale (20 à 30% des cas en pédiatrie), d'autre part l'étendue de la tumeur elle-même dans le rein et enfin la compression  par les adénopathies régionales. La présence d'une fonction rénale altérée complique encore la gestion de ces patients à risque élevé avant le traitement et également après le début de la chimiothérapie. Et ceci est un obstacle à l'utilisation d’une chimiothérapie potentiellement néphrotoxiques et de produit de contraste pour l'imagerie. Devrions-nous utiliser l'échographie, la tomodensitométrie sans produit de contraste ou l’imagerie par résonance magnétique pour la stadification et le suivi ? D'autres recherches peuvent répondre à ces questions.Conclusion : Les PNET de localisation rénale doivent être envisagées dans les tumeurs rénales de tous âges, mais plus particulièrement chez les enfants et les jeunes adultes. Cette tumeur a de nombreuses similitudes avec d'autres tumeurs rénales, il est important de diagnostiquer cette entité tôt avant l’apparition des complications et principalement l’insuffisance rénale

Neural network controller for active demand side management with PV energy in the residential sector

In this paper, we describe the development of a control system for Demand-Side Management in the residential sector with Distributed Generation. The electrical system under study incorporates local PV energy generation, an electricity storage system, connection to the grid and a home automation system. The distributed control system is composed of two modules: a scheduler and a coordinator, both implemented with neural networks. The control system enhances the local energy performance, scheduling the tasks demanded by the user and maximizing the use of local generation