Literatura académica sobre el tema "Simulation – Dissertation universitaire"
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Tesis sobre el tema "Simulation – Dissertation universitaire"
Vuillod, Bruno. "Stratégie de modélisation multi-fidélité via une approche système incluant des métamodèles basés sur les entités NURBS". Electronic Thesis or Diss., Paris, HESAM, 2024. http://www.theses.fr/2024HESAE003.
Texto completoThe more complex the problem, the greater the amount of computational resources needed to simulate it. On the other hand, the need for accuracy in the results of a system will not be the same depending on its design phase and the domain studied. The goal of this thesis is to propose a fast, low-cost multi-fidelity modeling strategy. To meet this need, a hybrid modeling approach is developed that combines Model-Based System Engineering (MBSE) and a metamodel based on Non-Uniform Rational Basis-Spline (NURBS) hypersurfaces. More specifically, the scientific challenge of this work is to develop a metamodel based on NURBS entities to simulate the behavior of highly nonlinear systems that require high fidelity modeling but are capable of providing results in real time to be compatible with the MBSE approach. In this context, the NURBS entity-based metamodel is obtained as a solution to an optimization problem solved with a gradient algorithm. In addition, a smoothing term is included in the problem formulation, not only to reduce the influence of any spurious nonlinearities in the training database, but also to limit the phenomenon of overfitting. The technical and scientific challenge of this work is to couple the general MBSE approach with the NURBS-based metamodel
Robberecht, Lieven. "Développement d’un simulateur canalaire endodontique pour des applications pédagogiques et de recherche". Thesis, Lille 2, 2015. http://www.theses.fr/2015LIL2S073.
Texto completoEndodontic therapy is often complicated and technically demanding. The “in vitro model” to simulate natural human teeth is highly needed for teaching and training dental students in pre-clinics or dental surgeons in continuing dental education courses. Moreover, remarkable development and research of endodontic technology also requires good model for in vitro performance evaluation prior to use on patients. Different practice models, including extracted human teeth, animal teeth or simulated root canals in epoxy resin blocks, etc., cannot satisfy the specific requirements. The objective of this thesis is to develop a process of fabricating a biomimetic dental root canal model (RCM) with a composition, microstructure and anatomy close to a natural tooth root. In order to overcome the limitations of existing RCMs, a ceramic root canal model (C-RCM) was developed, based on microporous hydroxyapatite (HAp), shaped by the casting method, with internal pulp cavity moulded by stereolithographic technique and finished by resin impregnation (to improve the tactile sensation during endodontic instrumentation). Many properties of this SC were shown comparable to the natural dental root: the same mineral component (HAp), porosity of 0-30%, the pore size of 0.8-5 µm, the good hardness (65-500 HV), the potential of customization of variable canal morphology, the suitable radio-opacity, etc. The pilot study on the evaluation of the application of this C-RCM by dental students was carried out and confirmed that better radiological behaviour for C-RCM than commercial resin RCM. This canal simulator poses no risk of infection, available in large numbers, allowing the objective assessment through its uniformity, therefore, well suits the endodontic practices and presents promising potential for training student or research on new endodontic technology
Fındık, Volkan. "Simulations atomistiques de la réaction d’acétylation d’amines et de l’inhibition covalente de l’enzyme Phosphoinositide 3-kinase (PI3K)". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0266.
Texto completoTargeted Covalent Inhibitors (TCIs) hold great promise for search of new drugs. They offer a number of potential advantages over traditional reversible inhibitors, such as extended residence time, increased potency, and the ability to make modifications for effective design. Kinase inhibitors are the most common examples of TCIs. Phosphoinositide 3-kinase (PI3K) enzymes are important drug targets in oncology as they are involved in the signaling pathway for many cellular functions such as growth control, metabolism and translation initiation. Lysine (Lys) residues have gained increasing interest as an alternative for targeted covalent inhibition. Recently, the first selective and irreversible inhibitors with ester groups as electrophilic head targeting the Lys779 residue and covalently inactivating the PI3Kδ enzyme were reported. The main objective of this thesis is to elucidate the mechanism of the covalent inhibition of PI3Kδ by these ester inhibitors in order to assist future design of new inhibitors with superior activities. Prior to the mechanistic studies on the enzyme, initially, we performed ab initio and DFT calculations on the model reaction between methylamine and methyl, phenyl and p-NO2 phenyl acetates in aqueous solution. The same model systems were then studied by the "dual-level" QM/MM molecular dynamics approach. For the “low-level” option, PM3/TIP3P umbrella sampling QM/MM simulations were applied for the sampling. The obtained structures were then used to obtain perturbative corrections to the free energy with a “high-level” QM region at the M06-2X/6-311+G(d,p) level. The results show that thefirst step involves the formation of the zwitterionic tetrahedral intermediate. Then, for sufficiently electrophilic esters, such as the p-NO2 derivative, the reaction proceeds by dissociation of the zwitterion as an ion pair, followed by proton transfer leading to the formation of the expected products. We, then, employed similar computational tools to shed light on the mechanistic aspects of the enzyme. First, an active site model of the enzyme was built through classical molecular dynamics simulations. Then, ONIOM QM:QM approach at the M06-2X/6 -31+G(d,p):PM6 level was applied to get possible reaction mechanisms in this active site. These calculations guided us to refine the reaction mechanisms in enzyme environment which globally confirm the steps obtained from the small model system. We finally used this information to approach a dynamic QM/MM study on the enzyme using the same“dual-level” protocol established for the small model system, which allowed us to obtain the free energy profile of the inhibition mechanism of PI3Kδ for p-NO2 derivative of the ester inhibitor. The calculated barrier is in good agreement with the available experimental kinetic data, which validates the proposed theoretical approach and the obtained mechanisms. Through the elucidation of the inhibition mechanism of previously experimentally tested compounds, our study paves the way for the discovery of new inhibitors with improved activity with the help of theoretical chemistry tools
Ejjaaouani, Ksander. "Conception du modèle de programmation INKS pour la séparation des préoccupations algorithmiques et d’optimisation dans les codes de simulation numérique : application à la résolution du système Vlasov/Poisson 6D". Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAD037.
Texto completoThe InKS programming model aims to improve readability portability and maintainability of simulation codes as well as boosting developer productivity. To fulfill these objectives, InKS proposes two languages, each dedicated to a specific concern. First, InKS PIA provides concepts to express simulation algorithms with no concerns for optimization. Once this foundation is set, InKSPSO enables optimization specialists to reuse the algorithm in order to specify the optimization part. The model offers to write numerous versions of the optimizations, typically one per architecture, from a single algorithm. This strategy limits the rewriting of code for each new optimization specification, boosting developer productivity.We have evaluated the InKS programming model by using it to implement the 6D Vlasov-Poisson solver and compared our version with a Fortran one. This evaluation highlighted that, in addition to the separation of concerns, the InKS approach is not more complex that traditional ones while offering the same performance. Moreover, using the algorithm, it is able to generate valid code for non-critical parts of code, leaving optimization specialists more time to focus on optimizing the computation intensive parts
Hullo, Marie. "Place des nanoparticules pour lutter contre la radio-résistance du cancer du sein : impact de l’hétérogénéité tumorale Gold Nanoparticle Uptake in Tumor Cells: Quantification and Size Distribution by sp-ICPMS . Radiation Enhancer Effect of Platinum Nanoparticles: Experimental in Vitrolimits Andrelevant Physical Chemical Simulation". Thesis, université Paris-Saclay, 2021. http://www.theses.fr/2021UPASL004.
Texto completoThe use of high-Z nanoparticles to enhance radiotherapy effects has gained momentum over the last decade. Historically, as nanoparticles increase tumor density, they were thought to improve radiation dose by locally increasing the probability of interactions with ionizing radiations. Local dose enhancement is then associated with increased oxidative stress and DNA damage. Therefore, radiosensitization with nanoparticles could impair radioresistance as well as improve therapeutic index. Radiotherapy is a cornerstone of breast cancer treatment. However, mammary tumors are heterogeneous and comprise distinct populations of cancer cells that respond differently to treatments. Cancer stem cells (CSC) and epithelial to mesenchymal transition (EMT) are major factors contributing to cancer cells plasticity, tumor heterogeneity, and escape from programmed cell death (apoptosis). In breast cancer, both CSC and cells undergoing EMT are characterized by the expression of two surface markers CD24 and CD44 (CD24-/low, CD44 high). This work aims to evaluate the efficiency of high-Z nanoparticles of different nature (gold, platinum), different size (from 5 to 35 nm) and different surface charge (positive and negative) as potent radiosensitizer on several breast cancer models of different epithelial or mesenchymal state. As no significant change could initially be observed in vitro following the combination of nanoparticles with radiation compared to radiation alone, I gain insight on the influence of physical, chemical and biological parameters required for characterizing radio-enhancement. Among them, I focused on improving the diffusion of nanoparticles and their internalization in tumor cells. I showed that nanoparticles uptake by breast cancer cells was depending on their mesenchymal state: nanoparticle internalization by cancer cells is dramatically increased in mesenchymal-like cancer cells compared to epithelial-like cells across a panel of several breast cancer cell lines. Importantly this discrepancy was not affected by the charge, size or surface chemistry of the nanoparticles themselves. This strongly suggests a cell-dependent mechanism, in opposition to the current paradigm that nanoparticles uptake is mainly governed by their inherent physical/chemical properties. This study emphasized the importance of membrane and extracellular structures in nanoparticle recognition and preferential interaction with cells. Our results are of peculiar interests as the identification of genes or mechanisms facilitating nanoparticles accumulation into radioresistant cancer cells could further conception of promising therapeutic nanoparticles
Bibin, Lazar. "Simulation 3-D d'anesthésie loco-régionale : neurostimulation et échographie". Paris 5, 2007. http://www.theses.fr/2007PA05S004.
Texto completoJean, Dit Gautier-Gaudenzi Estelle. "Modélisation du système pelvien de la femme enceinte et simulation d'accouchement : outil analytique et pédagogique". Thesis, Lille 2, 2018. http://www.theses.fr/2018LIL2S019/document.
Texto completoWe aim at developing a complete 3D numerical model of a parturient pelvic system representing all the anatomical structures of the pelvis such as ligament, muscle and organs. Then we generate a parametric FE model that allows simulating normal and dystocic vaginal delivery.We have developed a parturient pelvic numerical model at different gestational ages, 16, 32 and 38 weeks of gestation, (WG) and in postpartum (2months and 1year) from MRI. The different organs, muscles and ligaments of the pelvic system were segmented in order to generate a complete anatomical 3D model. Starting from this numerical model we studied the changes the muscles and ligaments undergo during pregnancy. Then we performed a Finite Element (FE) model that allows simulation and analysis of the deformations of pelvic anatomical structures under the stress induce by normal and dystocic vaginal delivery. In particular, we investigated the influence of the head size, terms and cephalic orientation and flexion. We particularly studied the structures that play an important role in the stability of the pelvic system.ResultsThe analysis during pregnancy of the US ligaments and levator ani muscle (LAM) reveals some geometrical modification, even then at the beginning of the second pregnancy trimester. This 3D anatomical model help to develop a teaching model for manual removing of the placenta, that could be integrated in a simple physic mannequin. The proof of pedagogical interest of this tool was made by different series of tests, underwent by gynaecolog-obstetrician and midwives. Then we worked with FE simulation of the vaginal delivery. The model developed is parametric. Than mean we can then change different maternal and fetal criteria such as gestational age, fetal head size, orientation and flexion. First place we performed normal vaginal delivery to study the impact of the fetal head descent in the pelvic system, and his stress impact on the different anatomical structures. Then we introduce dystocic element. We can evaluate and localize the strain levels and the most injured areas. Posterior cephalic presentation presents higher injury risk than the anterior one. Maternal geometry at different terms brings equivalent results contrary to the fetal head sizes that have an influence on the strain level and the potential damage induced. We developed pressure and trajectories sensors integrated in a forceps. We can then record an ex-vivo forceps extraction and then integrate all the information in the FE model.ConclusionThis multi-parametric investigation allows us to have a customizable and predictive tool evaluating the potential damages on the pelvis during vaginal delivery. We could then explain, understand and maybe predict some maternal and fetal complications that could happen during vaginal delivery. We can in particular try to explain the perinea injuries during, after and long time after vaginal delivery. This tool can be used to teach the complexity of obstetric
Risser, Fanny. "Études d’un mécanisme enzymatique et d’interactions inter-protéiques au sein de voies complexes de biosynthèse de polycétides Characterization of Intersubunit Communication in the Virginiamycin trans-Acyl Transferase Polyketide Synthase Understanding Intersubunit Interactions in the Enacyloxin Mixed cis- /trans-acyltransferase Modular Polyketide Synthase Insights into a dual function amide oxidase/macrocyclase form lankacidin biosynthesis". Thesis, Université de Lorraine, 2019. http://www.theses.fr/2019LORR0296.
Texto completoComplex polyketides are secondary metabolites which are produced by a range of different organisms, and which present a broad spectrum of therapeutic activity. The modular organization of the enzymes responsible for their synthesis, the polyketide synthases (PKS), makes them attractive targets for synthetic biology aimed at obtaining new polyketide structures. One of the most promising strategies to date consists in swapping of whole sub-units between different PKS systems. However, the success of this strategy critically depends on understanding and exploiting ‘docking domains’ the protein sequences at the C- and N-terminal extremities of the subunits which are responsible for correctly ordering the polypeptides, and therefore for faithful chain transfer. To increase our knowledge of DDs, we investigated several interfaces in both trans-AT and cis-AT PKSs. This work led notably to the identification of the first family of DDs from trans-AT PKSs, and we were further able to characterize a complete interface formed between two consecutive subunits within the virginiamycin PKS. In addition, we showed that at least one DD of matched pairs is often an intrinsically disordered region (IDR), as this type of interaction motif allows for specific but medium affinity contacts. Indeed, in the enacyloxin hybrid cis-AT/trans-AT PKS which we also investigated extensively, docking at every interface is mediated by a C-terminal IDR. In addition, we demonstrated that multiple structural classes of DD are present within the system, but that variations of the electrostatic ‘code’ within an individual structural class can also be used to ensure specificity. Taken together, these results provide important guidelines for future attempts to deploy DDs in subunit engineering. Another attractive target for synthetic biology are the so-called ‘post-PKS’ enzymes, which chemically decorate the initially-formed structure, and are often essential for their bioactivity. In this context, we studied LkcE, a bi-functional enzyme that catalyzes a rare amide oxidation followed by an intramolecular Mannich reaction to yield the lankacidin macrocycle – both to understand its unusual mechanism and to evaluate its suitability as a general polyketide modifying enzyme. We solved four crystal structures of the enzyme, and characterized it kinetically. Together, our data allowed us to propose a detailed catalytic mechanism for LkcE, involving a large-scale conformational change of the enzyme to bring the substrate into a cyclisation-ready state. Moreover, we showed that LkcE displays a certain tolerance toward its substrate structures, suggesting its usefulness as a general catalyst for cyclisation/ligation reaction in synthetic biology and chemical synthesis
Chabridon, Sophie. "Performances et fiabilite des systemes paralleles et distribues". Paris 5, 1996. http://www.theses.fr/1996PA05S002.
Texto completoDeyawe, Kongmeneck Audrey. "Investigation des mécanismes d’activation et de couplage du canal potassique voltage-dépendant KV7.1 dans les cardiomyocytes à l’aide de méthodes computationnelles". Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0175.
Texto completoKV7.1 is a voltage-gated ion channel that open to selectively diffuse K+ ions across the plasma membrane upon membrane depolarization. In the myocardium tissue, KV7.1 channel is co-expressed with the ancillary subunit KCNE1 to generate the IKS current during cardiac action potential. The mutations of KV7.1 and KCNE1that are linked to severe cardiac arrhythmias make KV7.1 channel a major therapeutic target. Each α-subunit of KV7.1 tetramer counts six transmembrane helices (S1 to S6), the first four ones forming the voltage-sensor domain (VSD), and the last two ones forming the pore domain (PD). This channel has a 2-step activation mechanism involving three stable states: resting, intermediate and activated. These conformations can induce pore opening or closure by a process called VSD-PD coupling. Accordingly, the states for KV7.1 channel are Resting/Closed (RC), Intermediate/Open (IO) and Activated/Open (AO). In the presence of KCNE1, the coupling is inhibited in the intermediate state, thus the states for IKS channel are RC, Intermediate/Closed (IC) and AO. Furthermore, the lipid PIP2 (phosphatidylinositol-4,5-bisphosphate) plays a crucial role in the VSD-PD coupling of KV7 channels. Despite the information drawn from both functional and structural studies of KV7.1, the modulation mechanisms of its VSD-PD coupling by KCNE1 and PIP2 remain unclear at an atomistic level. With the help of powerful computational tools, we designed molecular models of Kv7.1 in order to have a better understanding of its function. The study of these models, conducted in collaboration with Pr. Jianmin Cui’s research team (Washington University of Saint-Louis, USA) allowed us to obtain four novel results about the way Kv7.1 opens. Indeed, this joint study revealed a novel VSD-PD coupling mechanism that we conceptualized by a “hand-and-elbow” model likely to occur in all domain swapped (KV1- KV7) channels. The analyses of IKS MD trajectories suggest that KCNE1 disrupts the “hand-and-elbow” model. In addition, the interactions between KCNE1 and PIP2 form a tourniquet around the cytoplasmic region of S6, leading to pore closure in both RC and IC models. Finally, the S6 helix of KV7.1 has a motif SFF (338-340), highly conserved in KV7 family, which forms an unidentified hydrophobic gate in KV7.1 pore. Two of these results were confirmed by in vitro experiments conducted by our collaborators on this channel, which validates the quality of our models for innovative therapeutic research