Nouvelles méthodes d’intégration pour traiter la plasticité en X-FEM

La méthode d’intégration utilisée classiquement en X-FEM fait dépendre la position des points d’intégration de la position de la fissure, ce qui convient difficilement à l’étude de la propagation d’une fissure dans un milieu plastifié. En effet, des étapes de projection de champs sont alors nécessaires. Afin de s’en affranchir, cette contribution propose deux approches alternatives. La première s’appuie sur les schémas d’intégration standards tandis que la seconde propose de différencier les points d’intégration des points où le comportement est évalué. Les méthodes proposées se limitent aux cas des interfaces

Supercooling: A Promising Technique for Prolonged Organ Preservation in Solid Organ Transplantation, and Early Perspectives in Vascularized Composite Allografts.

Ex-vivo preservation of transplanted organs is undergoing spectacular advances. Machine perfusion is now used in common practice for abdominal and thoracic organ transportation and preservation, and early results are in favor of substantially improved outcomes. It is based on decreasing ischemia-reperfusion phenomena by providing physiological or sub-physiological conditions until transplantation. Alternatively, supercooling techniques involving static preservation at negative temperatures while avoiding ice formation have shown encouraging results in solid organs. Here, the rationale is to decrease the organ's metabolism and need for oxygen and nutrients, allowing for extended preservation durations. The aim of this work is to review all advances of supercooling in transplantation, browsing the literature for each organ. A specific objective was also to study the initial evidence, the prospects, and potential applications of supercooling preservation in Vascularized Composite Allotransplantation (VCA). This complex entity needs a substantial effort to improve long-term outcomes, marked by chronic rejection. Improving preservation techniques is critical to ensure the favorable evolution of VCAs, and supercooling techniques could greatly participate in these advances

Vacuolar ATPase Regulates Surfactant Secretion in Rat Alveolar Type II Cells by Modulating Lamellar Body Calcium

Lung surfactant reduces surface tension and maintains the stability of alveoli. How surfactant is released from alveolar epithelial type II cells is not fully understood. Vacuolar ATPase (V-ATPase) is the enzyme responsible for pumping H+ into lamellar bodies and is required for the processing of surfactant proteins and the packaging of surfactant lipids. However, its role in lung surfactant secretion is unknown. Proteomic analysis revealed that vacuolar ATPase (V-ATPase) dominated the alveolar type II cell lipid raft proteome. Western blotting confirmed the association of V-ATPase a1 and B1/2 subunits with lipid rafts and their enrichment in lamellar bodies. The dissipation of lamellar body pH gradient by Bafilomycin A1 (Baf A1), an inhibitor of V-ATPase, increased surfactant secretion. Baf A1-stimulated secretion was blocked by the intracellular Ca2+ chelator, BAPTA-AM, the protein kinase C (PKC) inhibitor, staurosporine, and the Ca2+/calmodulin-dependent protein kinase II (CaMKII), KN-62. Baf A1 induced Ca2+ release from isolated lamellar bodies. Thapsigargin reduced the Baf A1-induced secretion, indicating cross-talk between lamellar body and endoplasmic reticulum Ca2+ pools. Stimulation of type II cells with surfactant secretagogues dissipated the pH gradient across lamellar bodies and disassembled the V-ATPase complex, indicating the physiological relevance of the V-ATPase-mediated surfactant secretion. Finally, silencing of V-ATPase a1 and B2 subunits decreased stimulated surfactant secretion, indicating that these subunits were crucial for surfactant secretion. We conclude that V-ATPase regulates surfactant secretion via an increased Ca2+ mobilization from lamellar bodies and endoplasmic reticulum, and the activation of PKC and CaMKII. Our finding revealed a previously unrealized role of V-ATPase in surfactant secretion

Full-length human placental sFlt-1-e15a isoform induces distinct maternal phenotypes of preeclampsia in mice

<div><p>Objective</p><p>Most anti-angiogenic preeclampsia models in rodents utilized the overexpression of a truncated soluble fms-like tyrosine kinase-1 (sFlt-1) not expressed in any species. Other limitations of mouse preeclampsia models included stressful blood pressure measurements and the lack of postpartum monitoring. We aimed to 1) develop a mouse model of preeclampsia by administering the most abundant human placental sFlt-1 isoform (hsFlt-1-e15a) in preeclampsia; 2) determine blood pressures in non-stressed conditions; and 3) develop a survival surgery that enables the collection of fetuses and placentas and postpartum (PP) monitoring.</p><p>Methods</p><p>Pregnancy status of CD-1 mice was evaluated with high-frequency ultrasound on gestational days (GD) 6 and 7. Telemetry catheters were implanted in the carotid artery on GD7, and their positions were verified by ultrasound on GD13. Mice were injected through tail-vein with adenoviruses expressing hsFlt-1-e15a (n = 11) or green fluorescent protein (GFP; n = 9) on GD8/GD11. Placentas and pups were delivered by cesarean section on GD18 allowing PP monitoring. Urine samples were collected with cystocentesis on GD6/GD7, GD13, GD18, and PPD8, and albumin/creatinine ratios were determined. GFP and hsFlt-1-e15a expression profiles were determined by qRT-PCR. Aortic ring assays were performed to assess the effect of hsFlt-1-e15a on endothelia.</p><p>Results</p><p>Ultrasound predicted pregnancy on GD7 in 97% of cases. Cesarean section survival rate was 100%. Mean arterial blood pressure was higher in hsFlt-1-e15a-treated than in GFP-treated mice (∆MAP = 13.2 mmHg, p = 0.00107; GD18). Focal glomerular changes were found in hsFlt-1-e15a -treated mice, which had higher urine albumin/creatinine ratios than controls (109.3±51.7μg/mg vs. 19.3±5.6μg/mg, p = 4.4x10^-2; GD18). Aortic ring assays showed a 46% lesser microvessel outgrowth in hsFlt-1-e15a-treated than in GFP-treated mice (p = 1.2x10^-2). Placental and fetal weights did not differ between the groups. One mouse with liver disease developed early-onset preeclampsia-like symptoms with intrauterine growth restriction (IUGR).</p><p>Conclusions</p><p>A mouse model of late-onset preeclampsia was developed with the overexpression of hsFlt-1-e15a, verifying the <i>in vivo</i> pathologic effects of this primate-specific, predominant placental sFlt-1 isoform. HsFlt-1-e15a induced early-onset preeclampsia-like symptoms associated with IUGR in a mouse with a liver disease. Our findings support that hsFlt-1-e15a is central to the terminal pathway of preeclampsia, and it can induce the full spectrum of symptoms in this obstetrical syndrome.</p></div

Adaptive Neural Predictive Control of an Induction Machine

Mouloud Denai, N. Benouzza, and L. Berkane Krachai, “Adaptive Neural Predictive Control of an Induction Machine”, Paper presented International Conference on Electrotechnics, 5-7 October 1998, Oran AlgeriaPeer reviewe

Conceptual Model for Massive Open Online Blended Courses Based on Disciplines' Concepts Capitalization and Obstacles' Detection

Since its appearance, the MOOC (massive open online course) is gaining more and more intention of the educational communities over the world. Apart from the current MOOCs design and purposes, the creators of MOOC focused on the importance of the connection and knowledge exchange between individuals in learning. In this paper, we present a conceptual model for massive open online blended courses where teachers over the world can collaborate and exchange their experience to get a common efficient content designed as a MOOC opened to their students to live a better learning experience. This model is based on disciplines’ concepts capitalization and the detection of the obstacles met by their students when faced with problem situations (exercises, projects, case studies, etc.). This detection is possible by analyzing the frequently of semantic errors committed by the students. The participation of teachers in the design of the course and the attendance by their students can guarantee an efficient and extensive participation (an important number of participants) in the course, the learners’ motivation and the evaluation issues, in the way that the teachers designing the course assess their students. Thus, the teachers review, together with their knowledge, offer a better assessment and efficient connections to their students

STUDY AND NUMERICAL SIMULATION OF SOLAR SYSTEM FOR AIR HEATING

<p>The use of solar energy in sunny countries, is an effective outil for compensate the lack in the energy, their benefits are not related only to its economic benefits but especially for the environmental protection, so we must find solutions to the problems of pollution. This work is a theoretical study of a solar flat plate collector ; air is used as the heat transfer fluid. In this study, we established in first step the calculation of solar radiation in various sites in Algeria (Adrar, El Oued, Bechar, Biskra and Tamanrasset). The second step is the parameters influence study of the sites and climate on the performance of our collector. The results obtained are encouraging for the use of this type in the heating in the winter, also it can be used in different kinds of drying.</p

Analyse morphologique de films CrN. Corrélation entre contrainte résiduelle et résistivité de films de chrome

National audienceLes films minces de nitrure de chrome ont sensiblement attiré l'attention, ces dernières années. Attrait du à leurs excellentes propriétés physiques, chimiques et mécaniques. Une partie de cette étude a porté sur la caractérisation morphologique de couches minces dures de nitrure de chrome (Cr-N), élaborées par PVD sur substrats de silicium (100) par pulvérisation magnétron. Nous avons considéré l'influence de la température de recuit sur l'adhérence et la stabilité thermique de ces films. Nous avons procédé à des caractérisations en microscopie électronique à balayage (MEB) équipé en microanalyse X (EDX).Des recuits d'une heure, entre 600°C et 1000°C sous azote N2, effectués sur des revêtements CrN,de différentes épaisseurs entre 0.5 et 1µm, ont montré la stabilité thermique de ces revêtements aux basses températures. Les résultats obtenus en MEB et EDX sont comparés aux résultats en DRX.Cette étude porte aussi sur des dépôts de couches de chrome élaborés par pulvérisation RF cathodique (PVD). L'analyse des contraintes résiduelles par le dispositif des anneaux de Newton, pour différentes épaisseurs, montre l'existence d'un pic de contraintes entre 170 et 200 nm. La méthode des quatre pointes a été utilisée pour déterminer la résistivité des couches de chrome. La résistivité décroît fortement pour les petites épaisseurs (< 100nm), pour ensuite se stabiliser à une valeur moyenne de 30µ.Ohm.cm. Une corrélation entre l'évolution des contraintes et de la résistivité nous a permis de faire un essai d'interprétation sur la croissance des films

Pre-expanded thin DIEP free flap in pediatric upper extremity reconstruction for burn sequelae: A case report

International audienceDeep burns sequelae involving the upper limb are challenging even for experienced surgeons, mainly because local reconstructive options and donor sites are often compromised. The use of free flaps for this type of reconstruction remains difficult due to the small recipient vessel diameter and tendency to vasospasm. Moreover, pediatric cases bring the challenge to another level. We present the case of a 13-year-old girl presenting major retractile sequelae of the upper left limb, including complete wrist immobilization combining wrist hyper-extension, ulnar deviation deformity, and a ulno-carpal dislocation. She was referred to our department where a two-stage reconstruction was performed using a pre-expanded free deep inferior epigastric artery perforator (DIEP) flap. The first surgery consisted of placing two kidney-shaped expanders in a subfascial plane in the hypogastric region. Four months later, after a bi-weekly expansion, an excision of the scar tissue, and the DIEP flap transfer were completed. At the 12-month follow-up evaluation, both aesthetic and functional results were satisfactory, with a good contour and regained mobility of the wrist

Intérêt du dosage des marqueurs angiogéniques et antiangiogéniques dans la prise en charge de la prééclampsie [Clinical value of angiogenic and anti-angiogenic marker assay in preeclampsia]

Preeclampsia is a disease which originates in the placenta and is specific to human pregnancy. It is one of the main causes of maternal and perinatal morbidity and mortality. The introduction of assays for angiogenic and anti-angiogenic markers reflecting placental dysfunction, which lies at the root of preeclampsia, is a turning point in the management of women with suspected preeclampsia or with an atypical form of the disease. The sFlt1/PlGF ratio assay, which has been covered by health insurance since July 2019, is a valuable diagnostic aid : the disease can be ruled out, with a high negative predictive value, when the ratio is low, thus avoiding unnecessary hospital admission and premature delivery. A high ratio can help to confirm the diagnosis of preeclampsia, albeit with a lower positive predictive value