Technique de datation des échantillons riches en uranium par les séries de l'uranium en utilisant la spectrométrie gamma à basse énergie

Dating technique of samples rich in uranium by the series of the uranium by using the gamma spectrometry with low energyIn this work, a dating technique by the series of the uranium using the gamma spectrometry with Flow energy

Assessment of Computed Tomography Dose Index (CTDI) During CT Pelvimetry Using Monte Carlo Simulation

A pelvimetry examination is sometimes prescribed to a pregnant woman at the end of her pregnancy in order to assess the dimensions of her pelvis prior to childbirth. This examination has long been performed by using X-ray, but is now increasingly being replaced by CT-scan The objective of this study is to assess the radiation doses received during a practical CT pelvimetry examination performed using a Hitashi Supria 16-slice CT scanner. The radiation doses were estimated using Monte Carlo (MC)-based simulation with GATE code to model the 16-slice CT scanner machine. The GATE code operates using GEANT4 libraries. A polyymethyl metacrylate (PMMA) acrylic phantom of 32 cm diameter was modeled to represent the patient's body. X-ray energy spectrum generated using the SRS-78 spectrum processor was used for simulation. The simulation was executed with the same exposure parameters as the practical CT pelvimetry examination with dose parameters of 1 mGy, 0.9 mGy, and 36.6 mGy.cm, respectively, for the weighted CT dose index (CTDIw), the volume CT dose index (CTDIvol), and dose-length product (DLP). The MC simulation results provide dose parameters of 1.16 mGy, 1.07 mGy, and 43.6 mGy.cm, respectively, for the CTDIw, CTDIvol, and DLP. The differences between the simulation and the practical examination were 16 %, 18 %, and 18 %, respectively. These differences are considered in a quite good agreement. The results were also consistent with other similar studies. This work proves that the Monte Carlo simulation with the GATE code is usable to assess the patient doses during a CT pelvimetry examination

Datation des carbonates impurs au Maroc à l’aide de la méthode de déséquilibre radioactif 230Th/234U

Au cours de ce travail, nous avons entrepris une série de mesures uranium, thorium sur des carbonates impurs en utilisant la méthode de dissolution totale (TSD). La correction des âges des dépôts, témoin d’une/des phase(s) humide(s) durant laquelle (lesquelles) la précipitation des carbonates a eu lieu, a été effectuée au moyen des techniques isochrones. Les résultats isotopiques obtenus montrent que: (1) le Plateau Central Marocain a connu au moins, deux phases humides, la première antérieure à 350 ka et la dernière récente au cours de l'épisode climatique Holocène, (2) la région d'Abda Doukalla a connu plusieurs épisodes de précipitations des carbonates qui datent respectivement de >350 ka, 229 ka, 140 ka, 98 ka, 42 ka et 20 ka.Mots-clés : dépôts quaternaires, déséquilibres radioactifs, spectrométrie alpha, carbonates impurs, travertin, plateau central marocain, Abda-Doukkala

Impact of Tube Voltage on Radiation Dose (CTDI) and Image Quality at Chest CT Examination

During Computed Tomography (CT) scan examinations, it is important to ensure a good diagnosis by providing the maximum information to detect pathologies and this can be done with a reduced dose. In this respect, several methods of dose reduction have been studied and evaluated. This work investigates the effect of tube voltage while varying the tube current on image quality and radiation dose at Chest CT examination. This study was conducted on HITACHI CT 16 slice Scanner using two phantoms for evaluating the dose and image quality; a PMMA phantom and a CATPHAN 500. Two tube voltages of 120 KVp and 100 KVp have been used for some variation of the tube currents (mAs) and recording the values of the measured quantities (CTDIv, spatial resolution, contrast to noise ratio CNR and noise). The scanning with 100 KVp at Chest CT examination led to a reduction in CTDIv until 45 %, an increase of noise from 17 % to 45 %, and the Spatial Resolution fell slightly (6 and 7 pl/cm) compared to the 120 KVp. The CNR shows a slight regression from 11 to 22 % for the 120 KVp and 100 KVp. This study has shown that despite the increase in the image noise at low tube voltage 100 KVp, it is possible to reduce the radiation dose by up to 45 % without degradation of image quality at Chest CT examination. Further works will evaluate the effect of acquisition parameters in other CT examinations

Novel Clustering Method Based on K-Medoids and Mobility Metric

The structure and constraint of MANETS influence negatively the performance of QoS, moreover the main routing protocols proposed generally operate in flat routing. Hence, this structure gives the bad results of QoS when the network becomes larger and denser. To solve this problem we use one of the most popular methods named clustering. The present paper comes within the frameworks of research to improve the QoS in MANETs. In this paper we propose a new algorithm of clustering based on the new mobility metric and K-Medoid to distribute the nodes into several clusters. Intuitively our algorithm can give good results in terms of stability of the cluster, and can also extend life time of cluster head

Enhancenig OLSR routing protocol using K-means clustering in MANETs

The design of robust routing protocol schemes for MANETs is quite complex, due to the characteristics and structural constraints of this network. A numerous variety of protocol schemes have been proposed in literature. Most of them are based on traditional method of routing, which doesn’t guarantee basic levels of Qos, when the network becomes larger, denser and dynamic. To solve this problem we use one of the most popular methods named clustering. In this work we try to improve the Qos in MANETs. We propose an algorithm of clustering based in the new mobility metric and K-Means method to distribute the nodes into several clusters; it is implemented to standard OLSR protocol giving birth a new protocol named OLSR Kmeans-SDE. The simulations showed that the results obtained by OLSR Kmeans-SDE exceed those obtained by standard OLSR Kmeans and OLSR Kmed+ in terms of, traffic Control, delay and packet delivery ratio

Activités de l’uranium et du radium dans des échantillons d’eau naturelle au Sahara marocain

Measure of uranium and radium activities in some natural watersamples from Moroccan SaharaThe preliminary results of  238U, 234U, 226Ra, 228Ra and 228Th activities and of 234U/238U,228Ra/226Ra, 228Th/228Ra and 226Ra/238U activity ratios obtained for 8 wells, 5 drillings, 2 springs and 3 tap water samples collected in Laayoune and Es-Smara regions in the Moroccan Sahara are given in this work. The analyzed natural water samples have been  collected from sources situated in a desert region rich in phosphates. Except for the one water drilling sample no used by population, the calculation of  equivalent doses to the maximal activities for each isotope show that all measured activities are inferior to the maximum contaminant levels recommended by the International Commission of Radioprotection and they don't present any risk for population health. The obtained results are comparable to those already found in other regions in Morocco or in the world

Comparaison des activités des isotopes de l'uranium et du radium dans quelques échantillons d'eau de puits et de sources thermales au Maroc

Les activités des isotopes de l'uranium et du radium (234U,238U,226Ra,228Ra) ainsi que les rapports d'activité (234U/238U,226Ra/238U,228 Ra/226Ra) ont été mesurés, pour la première fois au Maroc, dans 15 échantillons d'eau de puits et 12 échantillons d'eau de sources thermales. Les résultats obtenus montrent que, contrairement aux eaux de puits, les eaux des sources thermales présentent des activités de238U relativement faibles et des activités de226Ra et des rapports234U/238U élevés. Les activités de l'uranium et du radium mesurées sont comparables à celles que l'on trouve habituellement dans d'autres régions non polluées du monde, elles sont inférieures aux limites maximales admissibles ce qui ne pose aucun risque pour la santé publique au Maroc.Activities and activity ratios of uranium and radium isotopes (234U,238U,226Ra,228Ra,234U/238U,226Ra/238U,228Ra/226Ra) have been determined, for the first time in Morocco, for 15 well water samples and 12 spring water samples. The obtained results show that, unlike well waters, the thermal spring waters present relatively low 238U activities and elevated226Ra activities and 234U/238U activity ratios. Uranium and radium activities are similar to those published for other non polluting regions of the world, they are inferior to the Maximum Contaminant Levels and don't present any risk for public health in Morocco

A library of recombinant Babesia microti cell surface and secreted proteins for diagnostics discovery and reverse vaccinology.

Human babesiosis is an emerging tick-borne parasitic disease and blood transfusion-transmitted infection primarily caused by the apicomplexan parasite, Babesia microti. There is no licensed vaccine for B. microti and the development of a reliable serological screening test would contribute to ensuring the safety of the donated blood supply. The recent sequencing of the B. microti genome has revealed many novel genes encoding proteins that can now be tested for their suitability as subunit vaccine candidates and diagnostic serological markers. Extracellular proteins are considered excellent vaccine candidates and serological markers because they are directly exposed to the host humoral immune system, but can be challenging to express as soluble recombinant proteins. We have recently developed an approach based on a mammalian expression system that can produce large panels of functional recombinant cell surface and secreted parasite proteins. Here, we use the B. microti genome sequence to identify 54 genes that are predicted to encode surface-displayed and secreted proteins expressed during the blood stages, and show that 41 (76%) are expressed using our method at detectable levels. We demonstrate that the proteins contain conformational, heat-labile, epitopes and use them to serologically profile the kinetics of the humoral immune responses to two strains of B. microti in a murine infection model. Using sera from validated human infections, we show a concordance in the host antibody responses to B. microti infections in mouse and human hosts. Finally, we show that BmSA1 expressed in mammalian cells can elicit high antibody titres in vaccinated mice using a human-compatible adjuvant but these antibodies did not affect the pathology of infection in vivo. Our library of recombinant B. microti cell surface and secreted antigens constitutes a valuable resource that could contribute to the development of a serological diagnostic test, vaccines, and elucidate the molecular basis of host-parasite interactions. Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved