An enhanced algorithm for complex permittivity extraction at microwave frequencies

An efficient technique of complex permittivity extraction is employed to characterize low-loss conventional dielectric materials at microwave Ku-band. The computational approach eliminates mathematically the systematic errors of the experimental setup. This method needs two uncalibrated S-parameter measurements. The first is performed with a sample under test and the second is done with an empty rectangular waveguide. Three low-loss dielectric materials (Celotex, Plexiglas and Teflon) are characterized to validate experimentally the extraction method over the Ku-band frequencies [12-18] GHz. The average relative errors between the calibrated and uncalibrated results are then calculated and compared. The proposed method has been improved using the mobile average to the experimental results obtained from the uncalibrated measurements, therefore, the stability is then enhanced

Intérêt des prothèses métalliques expansives dans la prise en charge de l’occlusion tumorale colique: expérience d’un service hospitalier Marocain

Le traitement de l'obstruction colique d'origine tumorale s'est modifié ces dernières années grâce à l'apport des endoprothèses coliques. Elles constituent une alternative thérapeutique reconnue au traitement chirurgical dans 2 indications: la levée en urgence de l'occlusion colique aigue avant une chirurgie curatrice ou pour le traitement palliatif de l'obstruction colique chez les patients inopérables ou ayant une maladie localement avancée ou métastatique. Il s’agit de 12 observations de syndrome occlusif colique d’origine tumorale traitées par endoprothèses coliques au sein du service de Gastro-entérologie 1 de l’hôpital militaire d’instruction Mohammed V. L’âge moyen était de 53 ans. Il existait une prédominance masculine (9 hommes - 3 femmes). Tous les patients présentaient un syndrome occlusif avec arrêt des matières et des gaz. L’abdomen sans préparation montrait des niveaux hydro-aériques chez tous les patients. La tomodensitométrie objectivait un processus colique sténosant avec dilatation des anses en amont. Tous les patients ont bénéficié de la mise en place d’une endoprothèse par colonoscopie sous anesthésie générale. Le succès technique immédiat et clinique était noté dans 95% des cas. La migration de la prothèse a été notée dans un cas. Les endoprothèses coliques constituent une alternative de choix au traitement chirurgical des sténoses tumorales coliques symptomatiques, soit pour permettre de préparer au traitement curatif chirurgical "à froid", soit dans un but palliatif avant de débuter une éventuelle chimiothérapie.Pan African Medical Journal 2013; 14: 6

Argania spinosa Leaves and Branches: Antiaggregant, Anticoagulant, Antioxidant Activities and Bioactive Compounds Quantification

Thrombocytes, also known as platelets, are crucial in maintaining the balance between blood clotting. Platelet hyperactivity and oxidative stress are the primary factors contributing to cardiovascular complications. Antithrombotic therapy remains one of the most effective treatments, but various potential side effects hinder its effectiveness, including the risk of haemorrhage. Intense research has been conducted on medicinal plants to discover the natural antithrombotic compounds. Argania spinosa, commonly known as the argan tree or argan oil tree, is a native species of southwestern Morocco. This study evaluated the primary and secondary hemostasis and antioxidant activity of leaf and branch aqueous extracts of A. spinosa and also assessed the phytochemical composition of these extracts. Platelet aggregation assay was performed using washed platelets stimulated with thrombin. For plasmatic coagulation, activated partial thromboplastin time and prothrombin time were measured using the poor plasma method. Bleeding time was evaluated by inducing bleeding at the tip of a mouse tail. The antioxidant activity of the extracts was determined through the DPPH, β-carotene, and FRAP methods. The presence or absence of the secondary metabolites was carried out with the help of specific reagents, and the quantitative analysis was carried out using spectrophotometric and colorimetric methods. The study results revealed the presence of phenols, total flavonoids, cardiac glycosides, tannins, and coumarins type of secondary metabolites in both types of aqueous extracts and a higher concentration of these was recorded in the leaves extracts. Both aqueous extracts significantly reduced in vitro thrombin-induced platelet aggregation, extended tail bleeding time, prolonged activated partial thromboplastin and prothrombin time and exhibited remarkable antioxidant activity. The leaf extract of A. spinosa exerts significant effects against thrombotic manifestations and could be a promising source of new antithrombotic compounds

Thermolabile Methylenetetrahydrofolate Reductase C677T Polymorphism and Homocysteine Are Risk Factors for Coronary Artery Disease in Moroccan Population

Increased plasma total homocysteine (tHcy) levels have been shown to be a risk factor for coronary artery disease (CAD). The common methylenetetrahydrofolate reductase C677T (MTHFR C677T) polymorphism has been reported to be a strong predictor of mild hyperhomocysteinaemia (HHcy). We assessed whether this mutation was associated with increased risk of CAD and plasma levels of tHcy. We also evaluated interactions between this polymorphism, mild elevated tHcy levels and conventional risk factors of CAD. Method. Using PCR-RFLP analysis, we studied the frequency of the C677T genotypes and its effect on CAD and on tHcy concentrations in 400 subjects without and with CAD angiographically confirmed. There were 210 subjects with CAD and 190 subjects without CAD. Results. The frequencies of the C677T genotypes were 53% (59.5% in controls versus 48.1% in cases), 34.8% (32.1 in controls versus 37.1 in cases), and 11.8% (8.4% in controls versus 14.8% in cases), respectively, for 677CC, 677CT, and 677TT. The genotype frequencies were significantly different between case and control groups (P < .05). The 677T allele enhances the risk of CAD associated to HHcy (P < .01). In multivariate analysis models, MTHFR C677T polymorphism effect on CAD was masked by other risk factors. HHcy was only and independently influenced by MTHFR polymorphism and smoking habits, and it is a strong predictor of CAD independently of conventional risk factors. Conclusion. Our data suggest that HHcy is strongly and independently associated to CAD risk increase; and MTHFR C677T polymorphism and smoking habits were the main predictors of tHcy levels. The CAD risk increase is mainly associated with mild HHcy in 677TT, whereas in 677CT and 677CC it is mainly associated with the conventional risk factors

Analyse dynamique des générateurs éoliens lors d'un creux de tension du réseau

International audienc

Polyagglutinability phenomenon: a case report and review of the literature

Abstract Background Polyagglutinability of red blood cells is a rare immunological phenomenon, it is due to a cryptic antigen that is abnormally present on the surface of red blood cells. The aim of our work is to shed light on polyagglutinability, which is still poorly understood cause of discordance between the cell and serum tests and can sometimes have harmful transfusion consequences. Case presentation We report the case of a 70-year-old African patient admitted for management of hemolytic anemia. Results During the erythrocyte grouping, a discordance between the cell and serum tests was observed, with polyagglutinability for the RH phenotype, a positive AB control, and even a positive control. The direct antiglobulin test and the Coombs test were also positive. The same results were obtained even after washing the red blood cells and incubating them at 37 °C for 30 min. For transfusion purposes, erythrocyte genotyping was performed, and the patient was transfused with an A+ red blood cell unit with an RH Kell-compatible phenotype. Conclusion Polyagglutinability should always be taken into account when grouping anomalies are encountered. Although it may not show any symptoms, hemolysis is frequently observed during transfusions

Line and Grid Impedance Impact on the Performances of a Parallel Connected Modular Inverter System

With the rising fuel cost, increasing demand of power and the concerns for global climate change, the use of clean energy make the connection of power electronics building bloc in the heart of the current research. The high output current applications make the parallel connection of modular inverters to be a solution for the use of low power building block inverters where the output power cannot be handled by a single inverter configuration. In this context, average-modeling using average phase–leg technique allows the n-parallel connected inverters to be analyzed accurately and rapidly without requiring the complexity of the full switched inverter topology. The obtained analytical solution along with the equivalent circuit model makes easier the design of the control loop. The analytical solution of the n-parallel connected inverters shows the impact of the line and grid impedance on the performance of the overall system. The impact of this coupling has to be investigated such that the main feature of paralleling inverters is guaranteed and that the inverter mode of operation will not be compromised. The main advantage of paralleling inverters can be lost for a certain coupling impedance considerations

Transient rotor current analysis of connected induction generator during grid disturbance

International audienc

Transient rotor current analysis of connected induction generator during grid disturbance

International audienc