Comportement du phosphore dans le sédiment des barragesde la partie aval du bassin versant d'Oum Rabiaa (Maroc)

L'étude du phosphore, facteur clef responsable de l'eutrophisation des eaux continentales, a été entreprise afin d'évaluer les potentialités de mobilité de cet élément dans les sédiments de la partie aval du bassin versant d'Oum Rabiaa : Imfout - Océan atlantique ; caractérisé par la présence de trois retenues de barrages en série (Imfout, Daourat et Sidi Maachou).La présence de ces trois retenues de barrages en série conditionne la répartition du phosphore des sédiments de ce tronçon en réduisant les apports fluviaux vers l'aval. La spéciation du phosphore des sédiments montre que le phosphore se trouve majoritairement sous forme inorganique (68 %) ; la fraction CaCO3 -P étant majoritaire par rapport à celle de Fe(OOH)-P. Les fractions organiques représentent 32 %. La mobilité mesurée du phosphate est de 20 % du phosphore total, les fractions du phosphore présentent une mobilité représentant prés de 15 % du PT. La différence mesurée entre la mobilité considérée par fraction et la mobilité totale, observée lors d'un cycle annuel, s'explique par la mobilité interne, au sein du sédiment, entre les différentes fractions. Les conditions environnementales (pH, oxygène dissous)en sont responsables puisqu'elles favorisent le relargage par une fraction en même temps que le stockage par une autre.The study of the phosphorus, factor responsible for the freshwater eutrophication, has been undertaken in order to evaluate potentialities of mobility of this element in sediments of the down part of the Oum Rabiaa basin (Imfout - Atlantic Ocean); characterized by the three dams in series (Imfout, Daourat and Sidi Maachou).The presence of these three dams in series is responsible of the distribution of the phosphorus in the sediments of this section by reducing fluvial contributions to the endorsement. The speciation of phosphorus of sediment show that the phosphorus was principally present in inorganic form (68%); the fraction CaCO3 -P was higher than that of the Fe(OOH)-P. The organic fractions represented 32% of total phosphorus. The phosphate mobility accounted for 20% of total phosphorus, the fractions mobility accounted for 15% of PT. The difference measured between the mobility considered by fraction and the total mobility, observed during of an annual cycle, was explained by the internal mobility, to the breast of the sediment, between the different fractions. Environnemental conditions (pH, dissolved oxygen) are responsible since they favor the release by a fraction at the same time that the stocking by an other

Characterizing Quantum Properties of a Measurement Apparatus: Insights from the Retrodictive Approach

Using the retrodictive approach of quantum physics, we show that the state retrodicted from the response of a measurement apparatus is a convenient tool to fully characterize its quantum properties. We translate in terms of this state some interesting aspects of the quantum behavior of a detector, such as the non-classicality or the non-gaussian character of its measurements. We also introduce estimators - the projectivity, the ideality, the fidelity or the detectivity of measurements perfomed by the apparatus - which directly follow from the retrodictive approach. Beyond their fundamental significance for describing general quantum measurements, these properties are crucial in several protocols, in particular in the conditional preparation of non-classical states of light or in measurement-driven quantum information processing

Qualité physico-chimique des eaux du réservoir Daourat ; impact e la vidange sur son fonctionnement

Ce travail concerne l'étude de la qualité physico-chimique de la masse d'eau du réservoir Daourat au Maroc ; situé sur le cours inférieur du bassin Oum Rbia. Une vidange du réservoir a lieu le 23 décembre 2001, l'impact de cette vidange sur la qualité physico-chimique de l'eau a été déduit à travers l'augmentation du débit à l'entrée et à la sortie du réservoir en décembre ; l'élévation du taux de la matière en suspension ; des concentrations en éléments nutritifs et de la chlorophylle " a ". Cette étude inclue également une analyse de régression qui a permis de déterminer une relation entre le phosphore et la chlorophylle " a " ; ainsi qu'une évaluation du niveau d'eutrophisation du réservoir Daourat.Les résultats fournis par les paramètres physico-chimiques ont révélé que la masse d'eau ne présente aucune stratification thermique ni anoxie et que le pH est alcalin. L'évolution des concentrations en éléments nutritifs dans la masse d'eau du réservoir dépend des apports exogènes et endogènes. Les apports exogènes sont dominés par les apports latéraux venant du bassin versant local peu boisé et caractérisé par un sol à vocation agricole responsable de l'enrichissement du milieu récepteur en éléments azotés. Les apports endogènes sont gouvernés par les interactions eau - sédiment suite à la minéralisation de la matière organique en période estivale et par le relargage d'éléments à partir du sédiment suite à la vidange et à la crue en période hivernale. L'impact de la vidange sur l'écosystème étudié a été déduit à partir des modifications des paramètres abiotiques et biotique enregistrés en décembre (période de vidange) dans le milieu du réservoir (S2) et son aval (S3). L'étude de la relation entre les orthophosphates et la chlorophylle " a " dégage une forte corrélation significative. Les données du phosphore et de la chlorophylle " a " classe le réservoir Daourat dans l'état hypereutropheThe Oum Rbia River is the longest river in Morocco with a total length of about 550 km. Studies conducted on this river have shown that agricultural activity is the main factor affecting the water quality. The current study focused on Daourat Reservoir, a part of the Oum Rbia River.The aim of this study was to investigate the water quality of the Daourat reservoir (physico-chemical parameters, nutrients and chlorophyll a) in order to estimate its eutrophication status. The influence of draining reservoir on water quality was also analysed. This survey also included a regression analysis that permitted the determination of the relationship between phosphorus and chlorophyll a, as well as an assessment of the level of eutrophication of the Daourat reservoir.A monthly survey was conducted to monitor changes in the hydrological cycle as well as possible seasonal variations during the period from 2001-2002. Water parameters (T°, pH, dissolved oxygen, suspended solids), nutrients (NH4+, NO3-, P-PO4, Tot-P) and chlorophyll a were determined according to standard French protocols (AFNOR, 1994). Annual nutrient inputs and outputs were calculated from the monthly discharge from the river and the monthly mean nutrient concentrations. The annual nutrient output was calculated similarly.The physico-chemical parameters and nutrient concentrations varied temporally in the Daourat Reservoir. The highest concentrations of nutrients were observed during summer and winter, with the lowest concentrations occurring in the spring. This evolution seemed to be influenced by the nature of the loads. Nutrient loading from the upstream regions of the reservoir was minimal compared to the contributions from the local catchment area and from internal loading from the sediments. Significant nutrient loading to the reservoir came from sediment resuspension on December 23, 2001 and by internal loading from sediments during the summer. The upstream reservoirs (Al Massira and Imfout) had minimal influence and were in fact responsible for the reduced fluvial contributions to the Daourat Reservoir. The increase in nutrient loads in the reservoir was responsible for high phytoplankton biomass, indicated by the high chlorophyll a values (mean 35 µg/L). The trophic state of the Daourat Reservoir was classified as hypereutrophic. Due to the large intra-annual variability of water quality, a properly designed monitoring program of reservoir water is recommended

DYNAMIC DISORDER AT INTERMEDIATE TEMPERATURE AND ITS EFFECT ON THE MAGNETIC PROPERTIES OF THE ORGANIC SUPERCONDUCTOR κ-(BEDTTTF)2Cu[N(CN)2]Br

The k-(BEDT-TTF)X superconducting salts, [where BEDT-TTF is bis(ethylenedithio)-tetrathiafulvalene, abbreviated as ET, and X is a monovalent anion like Cu[N(CN) ]Br 2 , and for either Cu[N(CN) ]Cl 2 or ( )2 Cu NCN and so on], exhibit interestinmagnetic and superconducting phase transitions [1]. They are quasi-two-dimensional and the interplane coupling is very weak. The basic structural unit is a dimer consisting of two BEDTTTF molecules stacked on top of one another. This layered structure leads to highly anisotropic electronic properties. These organic superconductors have similar characteristic superconducting properties including the intrinsic Josephson Effect and the mixed-state properties. This similarity suggests the existence of the vortex phase transition in the organic layered superconductors as observed in HTSC. Because the temperature scale is much lower in organic materials, the thermal fluctuation is expected to be small compared to HTSC. Thus, the comparison between the high-Tc and organic superconductors can give important clues as to the nature of vortex phase transitions. Besides these anomalies around 50 K, unusual time dependencies in magnetic and transport properties have been reported for both deuterated and hydrogenated k-Br near 80 K. For - H - Br 8 k , the superconducting properties have been found to depend on the thermal history, in particular on how fast the sample had been cooled through 80 K. As mentioned above, the ground state of - D - Br 8 k is strongly sample-dependent: both superconducting as well as non-superconducting crystals are found. Furthermore, superconducting as well as insulating (possibly antiferromagnetic) phases in separated volume parts of the same sample have been reported. Their relative volume fraction was found to depend on the cooling rate Vc employed at around 80 K[2-3-4]: in fast cooled samples, a strong decrease of the diamagnetic signal has been observed, which has been interpreted as indicating a suppression of the superconducting in favour of the magnetic phase

Une tumeur du vagin à ne pas méconnaitre, l’adénocarcinome mésonephrique: à propos d’un cas et revue de la literature

L'adénocarcinome mésonéphrique du vagin est une tumeur maligne extrêmement rare avec uniquement trois cas publiés dans la littérature jusqu'à maintenant. Il dérive des reliquats embryonnaires des canaux mésonéphriques au niveau du vagin. Nous rapportons un cas d'adénocarcinome mésonéphrique du vagin survenant chez une femme de 50 ans, et révélé par une masse polyploïde du vagin. L'IRM a montré un envahissement du périnée et de la branche inférieure du pubis. L'étude anatomo-pathologique était en faveur d'un adénocarcinome mésonéphrique dont les cellules tumorales expriment la pancytokératine et le CD10. Elles ne sont pas marquées par les anticorps anti récepteurs ostrogéniques et progestatifs. La patiente a été adressée pour radiothérapie avant la prise en charge chirurgicale. Les auteurs soulignent à travers cette observation les aspects étiopathogéniques, histologiques et thérapeutiques de cette tumeur rare

Flux flow noise in high Tc superconductors thin films

We have studied the fraction pinned of vortex in a type II superconductors. The sample used is the YBa2Cu3O7-d thin films. This fraction pinned is determined from the comparison of the experimental results and the theoretical results previously definite. In continuation one will study the variations of this fraction according to the temperature of the applied magnetic field and the electric current crossing the sample.We have studied the fraction pinned of vortex in a type II superconductors. The sample used is the YBa2Cu3O7-d thin films. This fraction pinned is determined from the comparison of the experimental results and the theoretical results previously definite. In continuation one will study the variations of this fraction according to the temperature of the applied magnetic field and the electric current crossing the sample

Pinning of vortices in superconductors at high critical temperature

Due to problem identification and enumeration of defects in HTC superconductors, the correlation between current density and the transition of vortex pinning volume is not completely mastered. However, many theoretical and experimental studies have been developed to better understand the problem of dissipation due to vortices in type II superconductors

The vortex motion and the magnetization study in YBa2Cu3O7-d single crystal

We have investigated the vortex motion and the magnetization of high critical temperature superconductors YBa2Cu3O7-d Measurements were made using a vibrating sample magnetometer technique. Several magnetization hysteresis cycles have been obtained for different angles, θ, between the applied magnetic field, H, and the crystallographic c-axis. For T = 30 K we observed a central peak and for T = 80 K we observed a second peak or "fishtail".We have investigated the vortex motion and the magnetization of high critical temperature superconductors YBa2Cu3O7-d Measurements were made using a vibrating sample magnetometer technique. Several magnetization hysteresis cycles have been obtained for different angles, θ, between the applied magnetic field, H, and the crystallographic c-axis. For T = 30 K we observed a central peak and for T = 80 K we observed a second peak or "fishtail"

The critical current density and the vortex pinning in high quality YBa2Cu3O7-d thin films

We have measured the critical current density Jc of high quality c-axis oriented YBa2Cu3O7-d thin films. Measurements were performed for various magnetic field and temperature values, and as a function of the angle q between the c-axis and the applied magnetic field direction. A maximum of the critical current density was obtained when the flux lines are aligned along the CuO planes (q = 90°); another maximum in Jc was also observed when the magnetic field is adjusted parallel to the c-axis. We attribute these effects to different, intrinsic and extrinsic, pinning mechanisms of vortices in the sample.We have measured the critical current density Jc of high quality c-axis oriented YBa2Cu3O7-d thin films. Measurements were performed for various magnetic field and temperature values, and as a function of the angle q between the c-axis and the applied magnetic field direction. A maximum of the critical current density was obtained when the flux lines are aligned along the CuO planes (q = 90°); another maximum in Jc was also observed when the magnetic field is adjusted parallel to the c-axis. We attribute these effects to different, intrinsic and extrinsic, pinning mechanisms of vortices in the sample