Tesis sobre el tema "Renflements sur le tube"
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Wu, Zhi-Qian. "Caveolin in membrane nanotubes : curvature sensing and bulge formation". Electronic Thesis or Diss., Université Paris sciences et lettres, 2024. http://www.theses.fr/2024UPSLS007.
Texto completoCaveolin is one of the major protein components of caveolae, which are small cup-shaped invaginations in the plasma membrane. It is synthesized in the endoplasmic reticulum in a signal recognition particle-dependent manner and transported to the Golgi apparatus via COPII-coated vesicles. At the trans-Golgi network (TGN), caveolin 8S complexes further oligomerize into 70S complexes with the facilitation of cholesterol. They are then sorted intotransport carriers through an unknown mechanism and transported to the plasma membrane. The conventional structural model of caveolin might suggest it is a curvature-sensing protein based on its hairpin molecular shape. However, a recently discovered structure model of the caveolin 8S complex in detergent micelles based on cryo-electron microscopy, which exhibits a flat disc geometry, raises questions about its curvature sensitivity.Furthermore, cavins, another major protein component of caveolae that cooperate with caveolins in bending the membrane to form caveolae, do not associate with caveolins at the TGN. Given that no other known candidate, apart from cavins, can cooperate with caveolin to form transport carriers at the TGN, it becomes unclear how these carriers for caveolin are formed there. Therefore, in this project, we aimed to elucidate the curvaturesensitivity and induction of caveolin. We addressed these issues by reconstituting caveolin-1 (Cav1) into the membrane of giant unilamellar vesicles (GUVs) and by performing tube-pulling experiments. The results showed that caveolin is indeed a curvature-sensing protein, with caveolin 8S complexes exhibiting approximately a 5 degree tilt from the horizontal, which endows them with curvature sensitivity. Furthermore, we showed that caveolin 8S complexes can collectively generate membrane curvature at low tension and form scaffolds on the tubes at high tension. In summary, our results showed that caveolin is a curvature-sensing and -inducing protein, suggesting the possibility of its sorting into transport carriers at the TGN based on these properties. Interestingly, we observed that above a certain membrane tension Tt that depends on Cav1 density, nanotubes pulled from Cav1-GUVs no longer exhibit a constant radius and that caveolins form bulges on the tube. To explore how Cav1 form these bulges, we first observed that on average, bulges' size decreases with an increase in membrane tension. We found that the bulge size is proportional to the total amount of caveolin in the bulge, suggesting a constant Cav1 density in the bulges. Additionally, higher density of caveolin in the membrane favors bulge formation and lowers Tt. These results suggest that when the tube radius decreases, caveolin might induce formation of bulges to relax mechanicalconstraints due to the tubular geometry, but a model and high resolution imaging are now needed to explain these observations
RAVAUX, JULIETTE. "Donnees sur la morphogenese du tube de riftia pachyptila". Paris 6, 1999. http://www.theses.fr/1999PA066423.
Texto completoREDJEL, SAID. "L'espace des metriques riemanniennes sur un tube, chirurgie riemannienne et applications". Paris 7, 1991. http://www.theses.fr/1991PA077077.
Texto completoBiswas, KIngshook. "Sur la géométrie des hérissons, et des tube-log surfaces de Riemann". Paris 13, 2005. http://www.theses.fr/2005PA132017.
Texto completoJames, Christopher. "Simulation du rayonnement de l'entrée atmosphérique sur les planètes gazeuses géantes". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLC085/document.
Texto completoExploration of the four gas giant planets, Jupiter, Saturn, Uranus, and Neptune, is important for understanding the evolution of both our solar system and the greater universe. Due to their size, flight into the gas giants involves atmospheric entry velocities between 20 and 50 km/s. This is a complex issue because the entry conditions are harsh but the related velocities are mostly beyond the capabilities of current ground testing facilities. As such, this thesis examines the possibility of experimentally simulating proposed Uranus and Saturn entries at 22.3 and 26.9 km/s in a free piston driven expansion tube, the most powerful type of impulse wind tunnel. Initially, the possibility of simulating the conditions directly by re-creating the true flight velocity was investigated. It was found to be possible to simulate the 22.3 km/s Uranus entry, but not without large uncertainties in the test condition. For this reason, it was proposed to use an established test gas substitition where the percentage of helium in the H2/He atmosphere is increased, or the helium is substituted for the heavier noble gas neon. This allows just the post-shock conditions of the entries to be simulated. Theoretically it was found that these substitutions allowed both Uranus or Saturn entry to be simulated, which was confirmed experimentally using helium. Noting the current interest in sending atmospheric entry probes to both of these planets, this study has demonstrated that the required experimental capabilities are available for performing simulated experiments using test models
Wrzosek, Laura. "Impact du microbiote intestinal sur l'homéostasie de l'épithélium colique : étude sur des modèles de rats gnotobiotiques". Paris 6, 2012. http://www.theses.fr/2012PA066600.
Texto completoThe intestinal microbiota is essential to our health by actively participating in the maintenance of intestinal homeostasis. The objectives are to study in gnotobiotic rats, the effect of the microbiota on the balance between proliferation and differentiation processes in colonic epithelial cells and to propose hypotheses on the mechanisms involved. We have shown that the transfer of a complex microbiota into germ-free rats reproduced a pattern of primocolonization and induced structural and functional maturation of the colonic epithelium with strong modulation of goblet cells. We have also demonstrated the ability of two commensal bacteria, Bacteroides thetaiotaomicron and Faecalibacterium prausnitzii, to modulate the differentiation of goblet cells, the synthesis and glycosylation of mucins. These effects would be linked at least in part by the production of acetate and butyrate. Finally, we have observed that Streptococcus thermophilus, a dietary lactic acid bacterium, induced a partial maturation of the colonic epithelium, particularly by stimulating goblet cells. Based on the specific metabolism of S. Thermophilus in the digestive tract and in accordance with our in vitro results, we propose that lactate may be a mediator of these effects. Thus, this work highlights the importance of the microbiota and the bacterial metabolites in the modulation of the intestinal barrier. This work provides new insights to understand how the microbiota modulates the homeostasis of the colonic epithelium and conversely how the host shapes the microbiota
AMIC, ALAIN. "Reflexion sur une pratique d'anesthesie en endoscopie digestive : experience de la clinique du chateau". Toulouse 3, 1993. http://www.theses.fr/1993TOU31092.
Texto completoNguyen, Dieu Linh. "La maison tube des nouveaux quartiers d'Hanoï : Effets de paramètres architecturaux sur l'ambiance thermique". Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/27525/27525.pdf.
Texto completoPilon, Dominic. "Influence des conditions aux limites sur les mesures acoustiques au tube à ondes stationnaires". Mémoire, Université de Sherbrooke, 2002. http://savoirs.usherbrooke.ca/handle/11143/1172.
Texto completoHuber, Baptiste. "Influence de facteurs géométriques du tube sur la dynamique et la précision des tirs". Thesis, Institut polytechnique de Paris, 2019. http://www.theses.fr/2019IPPAE006.
Texto completoThe objective of thesis is to study the movements of the tube and of the projectile which influence mutually. These correlations depend on distortions of the tube, on the speed and on the acceleration of the projectile. The distortion of the tube is due to the actions of contact of the projectile and to the pressure of gases applied to the tube behind the projectile. Acceleration of projectiles are so intense as every imperfection or movement of the tube will have an all the bigger influence on the movements of the projectile and so on his initial conditions of flight, and therefore on his final precision relating to the aimed point. Offered research work includes several stages and puts different disciplines into play: - Determination of the geometry of the tubes of weapon: methodology of measures. - Understanding of phenomena in phasis of internal ballistics: experimental trials, instrumentation of projectiles. - Identification of parametres influencing performances in shooting: statistical studies. - Modelling of the tossing of the munition: numerical simulation
Baillard, André. "Influence de raidisseurs longitudinaux sur la diffusion acoustique par un tube : théorie et expérience". Le Havre, 2000. http://www.theses.fr/2000LEHA0001.
Texto completoGarcia-Fouqué, Segunda. "Étude de la mesure de l'ozone par tube à diffusion : application sur le terrain". Compiègne, 1998. http://www.theses.fr/1998COMP1162.
Texto completoPilon, Dominic. "Influence des conditions aux limites sur les mesures acoustiques au tube à ondes stationnaires". Sherbrooke : Université de Sherbrooke, 2002.
Buscar texto completoMaillot, Céline. "Effets et mécanismes d'action du corticotropin-releasing factor périphérique sur la motricité colique chez le rat". Rouen, 2002. http://www.theses.fr/2002ROUE02NR.
Texto completoBligny, Dominique. "Mémoire alimentaire du tube digestif : conséquences des transitions aiguës et des déséquilibres alimentaires sur la physiologie digestive". Rennes 1, 2009. http://www.theses.fr/2009REN1B124.
Texto completoDifferent types of duodenal nutrients alter gastroduodenal mobility. On the contrary, few data are available on the gastroduodenal motor effects of acute diet changes or unbalanced diets, two situations generated by occidental type diets. We built two experimental animal models to study in one hand the effects of an acute diet change from an animal-based diet to a plant-based diet, and on the other hand the consequences of isocaloric unbalanced diets with fat or carbohydrates excess. Rapid diet changes reduce the sensitivity of duodenal vagal afferents when they are simulated by duodenal intralipid or differents neurotransmitters such as CCK or 5HT. This reduced sensitivity is causative for the reduced gastric emptying rate observed after rapid diet changes. Intrlipid duodenal administration in animals chronically feed with isocaloric high fat diet is unable to induce a reduction in gastric compliance, after antro-pyloro-duodenal motility pattern and ultimately lead to the suppression of the duodenal brake on gastric emptying. Some of these effects are also found with high carbohydrate diet. Finally, in the inteerdigestive state and without an additional intralipid administration the high fat diet but not the high carbohydrate one induces an alteration of the duration of the migrating motor complex. In conclusion, an overall desensitisation is observed, either at the level of the duodenal vagal afferent or at the level of the whole body, is respectively induced by rapid diet change and by high fat, and to a lower extend by high carbohydrate diets
GUIHOT, GWENAELE. "Influence d'une alimentation elementaire sur le systeme immunitaire associe au tube digestif et sur le metabolisme de l'arginine dans les enterocytes isoles de rats". Paris 7, 1997. http://www.theses.fr/1997PA077036.
Texto completoLiennard, Mathilda. "Dynamique des tubes parcourus à grande vitesse : influence de la géométrie des tubes et leur environnement sur la justesse et la dispersion". Thesis, Orléans, 2015. http://www.theses.fr/2015ORLE2033.
Texto completoGun accuracy is influenced by several factors during the stages of the ammunition course (internal, intermediate and external ballistics). According to previous studies, internal ballistics are the major contributor to deviations from target. Indeed, this phase determines projectile exit conditions and, consequently, his behavior during the flight. The projectile entry conditions, the weapon and barrel geometry and their movements during firing, can modify the interaction tube / projectile and change ammunition angular rates and its transversal velocities. The purpose of this thesis is to determine the parameters related to barrel and gun geometry, which influence the bias and the dispersion. A statistical analysis was led thanks to the data base of the 25 mm firing results. It was found that some parameters, including barrel straightness, affect accuracy. Subsequently, tests were conducted with a firing appliance in order to isolate the barrel geometry influence on the deviations from the target and to confirm the straightness impact. A tridimensional numerical model was created in order to vary this parameter and to study its influence on the ammunition behavior during internal ballistics. The representativeness of the model was validated using accelerometers embedded in the ammunitions. The firing of these ammunitions has required the development of an optoelectronic system to transmit accelerations in real time. The comparison between experimental and numerical results has shown close amplitudes and similar shapes curves that proves the representativeness of the model. The model can be used now to lead parametric analysis and to determine the straightness shapes the most penalizing for gun accuracy
Meslé-Visée, Vanessa. "Prévention par l'acide folique des anomalies de fermeture du tube neural : enquête sur les connaissances d'un groupe de femmes de la région parisienne". Paris 13, 2004. http://www.theses.fr/2004PA130031.
Texto completoBENMANSOUR, ABDELLATIF. "Etude expérimentale et théorique de la condensation de la vapeur en présence d'incondensables sur un tube lisse horizontal". Poitiers, 1992. http://www.theses.fr/1992POIT2281.
Texto completoMéance, Séverine. "Effets d'un lait fermenté par Bifidobacterium DN-173 010 sur le transit intestinal et le risque d'adénome colorectal : études chez l'homme". Dijon, 2003. http://www.theses.fr/2003DIJOMU03.
Texto completoDevesvre, Julie. "Sur la compréhension des phénomènes de couplage fluide-structure dans les propulseurs de fusée". Thesis, Aix-Marseille 1, 2011. http://www.theses.fr/2011AIX10132/document.
Texto completoIn a solid rocket motor, high pressure oscillations induced by aeroacoustic instabilities and fluid structure interaction (FSI) may lead to disturb rocket thrust and cause damages. In the rocket motors, flexible inhibitors made of insulating material are initially bonded to the propellant, and FSI is mainly induced by their displacement. In this context, a numérical approach to simulate FSI problems has been developped. Our method is based on the coupling of two dissociated codes : fluid flow is computed with CARBUR, while the dynamics of deformable structures is simulated by MARCUS. A hyperelastic behaviour law has been implemented in MARCUS in order to simulate the movement of flexible inhibitors. An experimental approach has been leaded in the shock waves tubes (T80) in our laboratory and as a validation of FSI coupling codes, numerical and experimental results have been compared
Soret, Rodolphe. "Impact du butyrate sur la plasticité du système nerveux entérique et les répercussions fonctionnelles". Nantes, 2011. http://www.theses.fr/2011NANT31VS.
Texto completoGastrointestinal functions are controlled by the enteric nervous system (ENS), independently of the central nervous system. The ENS is an integrated neuronal network localized along the gut and organized in two major plexus: the myenteric plexus, involved in the control of Gl motility and the submucosal plexus, involved in the control mainly mucosal functions such as electrolyte secretion, paracellular permeability and intestinal epithelial cell proliferation. Short chaine fatty acides (SCF A) mainly acetate, propionate and butyrate, are produced by bacterial fermentation of indigestible fiber contained in the colon. Butyrate is the primary energy source for the colonie epithelium and he modulates many œil functions such as proliferation, differentiation or apoptosis. The objective of this thesis was to study the impact of butyrate on the plasticity of the ENS and the functional implications of these effects. Ln vivo, rats fed a diet enriched in resistant starch or intra-colonic infusion of butyrate solution, we demonstrated a specifie increase and dose-dependent, the proportion of cholinergie neurons. This effect is associated with increased colonie motility. Ex-vivo treatment of muscular strip-myenteric plexus by butyrate increases cholinergie contractile response. Induction of a cholinergie phenotype by butyrate involved transporters MCT2 which were specifically deteeted in enteric neurons. Furthermore, we demonstrated that butyrate-induced ChAT expression involved the Src-kinase signaling pathway and the acetylation of histone H3 lysine 9. Ln addition, we developed a method for isolating and culturing primary enteric glial cells (EGC) from rat, mou se and human colonie tissues. Finally, we determined their functional role, in particular of human EGC, upon major intestinal epithelial and neuronal cell function
Zambaux, Julie-Anne. "Influence des déformations successives alternées de la paroi sur l'accroissement des performances d'échange d'un tube : application aux échangeurs multifonctionnels". Thesis, Valenciennes, 2014. http://www.theses.fr/2014VALE0036/document.
Texto completoThe work presented here is focused on the numerical study of specific successive wall deformations in alternate directions, applied to a tubular geometry. Those deformations help modifying the flow structure and thus its heat transfer and mixing properties. One of the main aims of the study is to apply those deformations to multifunctional exchangers which are heat exchangers and chemical reactors at the same time. The study is mainly focused on laminar flows and all the numerical calculations were performed using the CFD code ANSYS Fluent. The first step of the study is to assess the secondary flow created by the wall deformations. The influence of several deformation geometrical parameters has also been studied. In order to enhance the mixing in the deformed tube, the wall deformations have been applied to coaxial configurations (often used in the industry). Two kinds of annular configurations have been evaluated. At first, the wall deformations are applied to the external and internal walls of the coaxial tube. The effect on the heat transfer enhancement of the longitudinal and angular phase-shifting between the two deformations has been specifically assessed. The second configuration considered combines the alternate deformations on its external walls and a swirled internal wall. This particular annular configuration creates chaotic advection in laminar flows, therefore helping increasing the mixing. This geometry is used as a solar captor and helps increasing the global performances when compared with a smooth tube usually used. The last part of the presented work is focused on the experimental validation of the numerical results. Techniques such as PIV and LDA are used to measure local velocity fields in a plane duct with alternate deformations applied to its lower wall
Daubech, Jérôme. "Contribution à l’étude de l’effet de l’hétérogénéité d’un prémélange gazeux sur la propagation d’une flamme dans un tube clos". Orléans, 2008. http://www.theses.fr/2008ORLE2017.
Texto completoBrunet, Séverine. "Analyse des mécanismes d'action antiparasitaire de plantes riches en substances polyphénoliques sur les nématodes du tube digestif des ruminants". Toulouse 3, 2008. http://thesesups.ups-tlse.fr/339/.
Texto completoIn small ruminants, the current control of gastrointestinal parasitism relies on the use of chemical anthelmintics. However, due to the increasing development of resistances to chemical anthelmintics, the potential use of condensed tannin-rich plants represents an alternative solution to the chemical treatments, although the mode of action remains unknown. The objective of the current work was therefore to define the mechanisms of actions of condensed tannins on the infective larvae of gastrointestinal nematodes. First, we have confirmed that the consumption of a condensed tannin-rich plant decreased the establishment of infective larvae in the host. In a second step, it has been shown that both the exsheathment and the penetration of the larvae in the host mucosae were disturbed after contact with condensed tannins. The observations of the ultra-structural modifications and the fixation of condensed tannins on the larvae have confirmed a direct mode of action. In addition, our results have shown that the effects of condensed tannins were non specific of the nematode species but that differences in susceptibility exist between the ensheathed and exsheathed larvae. The effects were also dependent of the concentration and the biochemical nature of the condensed tannins. Finally, hypotheses on the potential interactions at the molecular level between the condensed tannins and the infective larvae are suggested
Dion, Carine. "Effets de lactobacillus casei sur le système immunitaire muqueux digestif de l'enfant". Nancy 1, 2000. http://www.theses.fr/2000NAN10207.
Texto completoRamphul, Somduth. "L'endoscopie digestive haute chez les personnes âgées : à propos d'une étude rétrospective portant sur deux-cent-trente-six patients âgés de soixante-dix ans et plus du centre de gériatrie (Hôpital Xavier Arnozan - 33604 Pessac)". Bordeaux 2, 1989. http://www.theses.fr/1989BOR25229.
Texto completoAkpa-Vinceslas, Marthe. "Activité cellulolytique liée au tube digestif d'Eisenia fetida andrei. Impact sur la dynamique de la matière organique de déchets lignocellulosiques". Rouen, 1998. http://www.theses.fr/1998ROUES030.
Texto completoSalemi, Bamdad. "Contributions expérimentales sur les écoulements diphasiques dans un évaporateur de climatisation : essais en eau-air et en réfrigérant R134a". Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0282/document.
Texto completoUnderstanding of multiphase flows in mini-channel evaporators is essential for the performance of air-conditioning systems, particularly in automotive sector. This thesis is mainly interested in behavior of inlet flow and phase distribution in the mini-channels. Initially, an adiabatic two-phase flow at the evaporator's inlet was studied. A transparent experimental apparatus with the same geometry as an evaporator's inlet has been designed. This test section helped us to reproduce the same flow regimes with air-water as flow regimes encountered with R134a in an evaporator. Several characterization techniques were used (visualization, conductance probes, Pitot tube and pressure taps) to determine pressure losses, liquid film thickness and gas velocity in a predominantly annular flow regime. Following the same principle, another experimental facility in stainless steel was developed to directly characterize the R134a flow at the evaporator's inlet. Finally, we have extended the study to the case of a compact evaporator in two adiabatic situations: single-phase (water) and two-phase (air-water). Pressure losses, phase distribution along the evaporator and flow regime in mini-channels were studied on an evaporator made of transparent materials (polycarbonate) with a close geometry to that of a real evaporator. Numerous results were obtained to provide a consistent database that would be useful for numerical simulation of this type of two-phase flows
Carpentier, Jean-Baptiste. "Influence d’une onde acoustique plane transverse sur l’atomisation des jets liquides non-assistés cylindriques à faible vitesse". Rouen, 2007. http://www.theses.fr/2007ROUES072.
Texto completoThis survey consists in a theoretical and an experimental study of non-assisted cylindrical liquid jets under transverse planar acoustic waves. Experiments show that acoustic velocity can lead to severe atomization. Two different breakup modes are pointed out and described which depend on the nozzle diameter. It is also reported that jet trajectory can deviate under specific acoustic conditions. Two theoretical models are proposed. The first one consists in a modal analysis of the vibrations of a jet when it flows into a transverse stationary acoustic field ; it shows the underlying physical phenomenon which is responsible for one of the breakup mode experimentally observed. The second model calls out for acoustic radiation pressure to explain deviation of jets
Dupart, Yoan. "Impact de la chimie des poussières minérales sur la photochimie atmosphérique". Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10292/document.
Texto completoThe objective of this work is to study the heterogeneous processes of mineral dust surfacesunder UV-A radiation. It is know that mineral dust containing metal oxides which can absorbsolar radiation and therefore activate a different chemistry compared to that observed in thedark. In order to avoid measurement artifacts related to the nature of macroscopic films, anaerosol flow tube was developed during this work and applied to study the interactions ofSO2, NO2 and O3 with real mineral dust.An unexpected formation of new particles in the presence of SO2 was observed. In order toexplain this phenomenon, we suggest the desorption of OH radicals from the mineral dustsurface to the gas phase. This mechanism has also been supported by field campaigns.Using real samples of volcanic ash from the last eruption of Eyjafjallajökull in Iceland (2010)allowed us study capture of SO2 on macroscopic ashes films with uptake coefficient around10-7. Associated kinetic experiments combined with chemical analysis allowed us to propose areaction mechanism explaining the formation of iron sulfate on the surface of ashes.Finally, we investigated the photochemical interactions of O3 and NO2 with minerals dustaerosols in the flow tube reactor showing a good agreement with previous data obtained onmacroscopic surfaces
Perez-Ruiz, Rodolfo. "Incidence de la flore digestive, du régime alimentaire et de l'implantation de lactobacilles à caractère décarboxylant sur les teneurs en histamine de la paroi du tube digestif du poulet et du rat". Paris 11, 1988. http://www.theses.fr/1988PA112383.
Texto completoTlili, Sabrine. "Etude des cinétiques et des équilibres d'adsorption des composés organiques volatils et semi-volatils présents dans l'atmosphère des salles blanches sur les composants microélectroniques en cours de fabrication". Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4806.
Texto completoAs semiconductor devices become smaller, it is increasingly important to reduce the degree of organic contamination in the areas where such devices are produced. It has been shown that cleanrooms are indispensable to provide a suitable environment for processing semiconductor devices. However, at present time there is no technology for controlling the contamination with volatile organic compounds (VOC), and even in such an environment, the wafers are exposed to VOC. A new experimental approach has been developed in our laboratory in order to follow the adsorption and desorption processes of volatile and semi volatiles organic compounds on silicon wafer surfaces. This unique setup is based on three principal components: a stable gas-phase generator, a flow tube reactor, and a proton-transfer-reaction–mass spectrometry (PTR-MS) analytical device to monitor the VOC. The adsorption behavior of five the most abundant VOCs in the cleanroom environment (isopropanol, acetone, xylene, ethyl acetate and propylene glycol methyl ether acetate) and three semi volatile organic compounds (diethylphtalate, tri-(2-chloroethyl)-phosphate and tri-(2-cloropropyl)-phosphate) on silicon wafer surface was studied. The kinetic parameters were determined and correlations between the gas phase concentrations and the surface densities of the organic contaminants were established. By comparing the adsorption properties of the studied compounds, it has been demonstrated that time dependant changes in the surface concentration of the organic species are governed by desorption constants, kdes. Moreover, kdes was found to be dependent on the molecular weight of the studied organics
Atig, Mérouane. "Non-linéarité acoustique localisée à l'extrémité ouverte d'un tube. Mesure, modélisation et application aux instruments à vent". Phd thesis, Université du Maine, 2004. http://tel.archives-ouvertes.fr/tel-00009283.
Texto completoDans une première partie, des mesures de l'impédance terminale réalisées à l'aide d'une méthode à deux microphones montrent que les pertes à la sortie du tube - partie réelle de l'impédance terminale dans le cadre de l'approximation du premier harmonique - augmentent avec l'amplitude de la vitesse acoustique. Les résultats montrent que l'importance de ces pertes dépend fortement du rayon de courbure des bords intérieurs à la sortie de tube. En outre, pour les faibles rayons de courbure, deux régimes sont mis en évidence. L'existence de ces deux régimes est confirmée par des observations utilisant la vélocimétrie par imagerie de particules (PIV) réalisées en collaboration avec l'Université d'Edimbourg : dans les deux cas un anneau tourbillonnaire est formé à la sortie du tube mais dans le cas du premier régime (faibles vitesses acoustiques) l'anneau reste accroché aux bords du tube alors que dans le cas du second régime (fortes vitesses acoustiques) il est expulsé.
La seconde partie concerne la modélisation du phénomène dans le but de mieux comprendre les mécanismes physiques mis en jeu. La théorie du bruit tourbillonnaire (``vortex sound theory'') est appliquée afin d'estimer directement les pertes à la sortie du tube. Trois calculs utilisant cette théorie sont menés : le premier, analytique, sur la base d'un unique anneau tourbillonnaire fixe ou mobile, le second à partir des mesures par PIV et le troisième par la méthode numérique dite des réseaux de Boltzmann. Les trois calculs conduisent à des résultats similaires qui démontrent que les pertes non linéaires trouvent leur origine dans la formation d'anneaux tourbillonnaires en sortie de tube. Ces résultats sont confrontés avec succès aux résultats issus des mesures d'impédance.
La troisième partie analyse les conséquences que peuvent avoir les pertes non linéaires dans le fonctionnement d'un instrument de musique à trous latéraux. Il est montré expérimentalement et à l'aide de simulations numériques que la dynamique de jeu d'un instrument à vent dépend directement des pertes dans l'instrument et que cette dynamique peut être étendue lorsque les pertes à la sortie sont minimisées par exemple en chanfreinant les bords des trous latéraux.
Mohamed, Ahmed ben. "Impact des fibres alimentaires et des acides gras à chaîne courte sur le dialogue tube digestif, foie et tissus périphériques, dans le cadre d'une surnutrition". Thesis, Université Clermont Auvergne (2017-2020), 2018. http://www.theses.fr/2018CLFAS026.
Texto completoHypercaloric diets are one of the causes of the increased obesity prevalence worldwide (and particularly in western countries). Conversely, dietary fibers consumption is associated with a better health status. Yet, dietary fibers consumption in western countries (20 g/d in France) is below the values of dietary fiber intake recommended by health care organizations (30 g/d). One of the ways to increase fiber intake in populations is to supply fiber-enriched foodstuffs, and particularly food products enriched with fibers capable to improve metabolic health (i.e. fermentable fibers). The aim of this thesis was to determine if, in overfed minipigs, dietary fermentable fibers supplementation included in a regularly consumed food (i.e. bread), was capable to limit the obesity-linked metabolic disorders induced by overfeeding. Fourteen female minipigs were overfed for 2 months with a diet supplemented with sucrose (10% w/w) and palm oil (10% w/w) associated with a supplementation (or not) of fibers (25 g/d, pectin, inulin & resistant starch) included in a specially designed bread (250 g/d ingested). Animals were multicatheterized at the gut and hepatic levels for net splanchnic nutrients fluxes measurements over the experimental period. Feces were also sampled for microbiota composition and activity analysis. Animals were euthanized after 56 days of nutritional treatment and tissues sampled (caecum, jujunum, liver, muscle, adipose) for metabolic phenotyping (histology, qRT-PCR, proteomics).We have shown that fermentable fibers supplementation, in a situation of overnutrition for 56 days, was capable to limit body weight gain and lipids droplets accumulation in the liver. We also observed a stimulation of the oxidative capacity in peripheral tissues (particularly the muscle). The decreased lipids droplets accumulation within the liver was due to a decreased entry of lipids (Fabp1) and a probable decreased lipogenesis (Srebp-1c). This mechanism, confirmed by the analysis of net nutrients fluxes, induced an increased bioavailability of energy nutrients to peripheral tissues. This excess of nutrients was handled by the muscle that increased its oxidative capacity (↑ mRNA Pgc1α, Pparα, Nrf2, Acox, Ucp2, sdha, Cpt1-m). This altered liver-muscle cross talk could be regulated by an increased release of GLP1 and / or GLP2 by intestinal L cells (↑ mRNA jejunum GCG) and stimulation of short chain fatty acids receptor (SCFA) GPR41 in caecum (↑ mRNA). A direct action of SCFA directly on peripheral tissues is highly improbable. As a conclusion, fermentable fibers supplementation, even during overfeeding, was beneficial for metabolic health via an impact on tissues cross talk and metabolic activities regulations. The next step would be to test a similar nutritional strategy in human being
Glémain, Pascal. "Etude experimentale de la resistance a l'ecoulement dans un tube collabable : consequences sur l'evaluation de la resistance urethrale et la comprehension de l'hydrodynamique urethrale chez l'homme". Nantes, 1994. http://www.theses.fr/1994NANT18VS.
Texto completoHenni, Hossein. "Étude numérique de la condensation en convection forcée d'un mélange de vapeur de méthanol et de gaz non condensables sur la paroi interne d'un tube vertical". Perpignan, 2007. http://www.theses.fr/2007PERP0772.
Texto completoThis study is devoted to a numerical modelisation of the film condensation of a methanol - noncondensables gases mixture inside a vertical tube. The wall of this one is considered firstly isotherm and secondly cooled by an external air flow. The transfers in the liquid and vapour phases are governed respectively by the classical stream equations and the forced convection ones. The pressure radial gradient and the diffusion terms are included in the momentum equation. The dimensionless transfers equations are solved by the finites volumes method and the Thomas and Gauss algorithms. In the vapour phase, the linkage between the pressure and the velocity fields is assumed by the SIMPLE algorithm. The results are presented as the velocity, the temperature, the vapour mass fraction and the pressure profiles. Correlations of the average Nusselt and Sherwood numbers function of the inlet vapour Reynolds number and Jacob number are presented. The results show that the condensation rate increases as the vapour Reynolds number increases and as the nonconcondensable mass fraction decreases. The cooling of the wall improve the transfers and consequently the condensation. The vapour Reynolds number has more effect on the transfers than the difference between the temperature of the mixture and the wall one. The including of the pressure radial gradient in the momentum equation conduce to an intensification of the transfers
DUPART, YOAN. "Impact de la chimie des poussières minérales sur la photochimie atmosphérique". Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-00942848.
Texto completoPonsot, Bernard. "Influence de la matrice sur le comportement a long terme de composites carbone-epoxyde". Paris, ENMP, 1987. http://www.theses.fr/1987ENMP0058.
Texto completoMonnier, Sylvain. "Étude physique de nanoassemblages biologiques de géométrie cylindrique : Effets de pression et couplage mécano-chimique sur des microtubules et des tubes de membrane". Montpellier 2, 2009. http://www.theses.fr/2009MON20194.
Texto completoMicrotubules are major constituents of cell cytoskeleton, they are highly dynamic cylindrical structures resulting of tubulin dimer self-assembly. They play fundamental role in cellular processes such as mitosis or cell trafficking. Using spectroscopy methods we studied the stability and aggregation properties of tubulin dimers and microtubules under hydrostatic pressure constraint. We show that pressure can dissociate tubulin oligomers or dimers in a concentration dependent manner. Hydrostatic pressure modifies microtubule polymerization properties and induces depolymerization. The study of tubulin reaction kinetics provides further understandings of the effect of hydrostatic pressure on this complex protein assembly. Biological membranes can form intra- and extra-cellular tubes which play fundamental roles in cytoplasmic trafficking. Using a theoretical approach, we studied the mechanical properties of tubular lipid membrane (TLM) under force and pressure difference constraints. We show the existence of a stability domain of the TLM whose boundaries define two kinds of instabilities. The first instability appears under a compressive force, while the second under a stretching force. For higher streching forces, radial fluctuations lead to tube shape with similarities with the “pearling” instability. This theoretical framework allows us to study protein adsorption and protein-protein interactions on a TLM. Instabilities induce a resonant behavior of the tube leading to global desorption of the adsorbed proteins. We also show long range protein-protein coupling mediated by the stress field in the tube membrane. This behavior can describe the process of protein cluster nucleation on a tubular membrane
Burlot, Philippe. "Effet du confinement plastique sur la stabilité mécanique des défauts dans les gazoducs : vers l'utilisation des éprouvettes SENT pour la caractérisation de la résistance à la fissuration des défauts dans les gazoducs". Thesis, Paris, ENMP, 2015. http://www.theses.fr/2015ENMP0076/document.
Texto completoIn this thesis the influence of plastic constraint at a crack tip on the mesured tough-ness of a material has been evaluated. After a study of the microstructure of the material, an ex-perimental study of its mechanical behaviour was made. A complex model combining an anisotrope hardening with an anisotrope damage law including a geometry contridution by means of the Lode parameter was then used. The porject ends with a study of the bursting test of a precracked line pipe. We can conclude from this test that the SENT specimen is more suitable for the study of thin tubes
Ngadjeu, Djomzoue Alain narcisse. "Etude des effets de gaine induites par une antenne de chauffage à la fréquence cyclotronique ionique (FCI, 30-80 MHz) et de leur impact sur les mesures par sondes dans les plasmas de fusion". Thesis, Nancy 1, 2010. http://www.theses.fr/2010NAN10118/document.
Texto completoThis work investigates the problematic of probe measurements in RF environment. DC currents flowing along magnetic field lines connected to powered ICRF antennas have been observed experimentally. Negative (i.e. net electron) current is collected on the powered ICRF antenna structure, while positive (i.e. net ion) current is collected by magnetically connected Langmuir probes. An asymmetric model based upon a double probe configuration was developed. The ICRF near field effect is mimicked by a ?driven? RF electrode at one extremity of an "active" open magnetic flux tube, where a purely sinusoidal potential is imposed. The other connection point is maintained at ground potential to model a collecting probe. This "active" flux tube can exchange transverse RF currents with surrounding "passive" tubes, whose extremities are grounded. With simple assumptions, an analytical solution is obtained. We can thus explain how DC currents are produced from RF sheaths. This model also makes it possible to model the characteristics DC Current' DC Voltage of a probe in the presence of RF and thus to evaluate some plasma properties. In this case the electrode at ground potential (probe) is polarized at a given potential. Analytical results are found within certain limits
Rossanigo, Carlos Esteban. "Rôle de l'eau et de la température sur les taux de développement des nématodes parasites du tractus digestif des ruminants". Montpellier 2, 1992. http://www.theses.fr/1992MON20293.
Texto completoZhang, Liping. "Immobilisation de catalyseurs moléculaires de polymérisation d’oléfines sur nanomatériaux". Thesis, Toulouse, INPT, 2014. http://www.theses.fr/2014INPT0013/document.
Texto completoThis present thesis deals with the development of active olefin polymerization catalysts based on late transition metal (nickel and iron) imino-pyridine complexes supported on nanomaterial. Chapter I gives a comprehensive literature review of unsupported and supported ethylene polymerization catalyst. In Chapter II we report the ethylene polymerization studies using nickel complexes containing an –NH2 group for covalent immobilization on multi-walled carbon nanotubes (MWCNTs) of the corresponding precatalysts. Comparison of the homogeneous catalysts with their supported counterparts evidenced higher catalytic activity and higher molecular weights for the polymers produced. In Chapter III, iron complexes containing a pyrene group have been synthesized and immobilized on MWCNTs through non-covalent π-π interactions between pyrene group and surface of MWCNTs. Activated by MMAO, both the iron complexes and immobilized catalysts show high activities for ethylene polymerization. It was possible to evidence that MWCNTs have a great influence on the catalytic activity and on the structure of the resulting polyethylenes. Imino-pyridine nickel complexes containing various kinds of aromatic groups have been synthesized in Chapter IV and polymerization conditions in the presence and in the absence of nanocarbon materials, such as MWCNTs or few layer graphene (FLG), are discussed. For those nickel catalysts bearing 1-aryliminoethylpyridine ligands, the presence of MWCNTs in the catalytic mixture allows the formation of waxes of lower molecular weight and polydispersity, whereas the presence of FLG proved to be beneficial for the catalytic activity. In Chapter V, isoprene polymerization catalyzed by iron complexes containing polyaromatic groups and non-covalently supported on nanoparticles and confined into the inner cavity of MWCNTs (Cat@NPs and Cat@NPs@MWCNTs) are investigated. Iron complexes show excellent activity for the isoprene polymerization and produced high glass temperature polyisoprene with a high trans-1,4-polyisoprene selectivity. Polymer nanocomposites are produced by supported catalysts and, transmission electron microscopy (TEM) evidenced efficient coating of the resulting polyisoprene around the oxygen sensitive iron nanoparticles
Pérez-Ruiz, Rodolfo. "Incidence de la flore digestive, du régime alimentaire et de l'implantation de lactobacilles à caractère décarboxylant sur les teneurs en histamine de la paroi du tube digestif du poulet et du rat". Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37617500n.
Texto completoKhalfi, Mohammed-Seghir. "Étude de l'influence de l'humidité de l'air sur le coefficient de transfert de chaleur d'une batterie froide en présence ou non de condensation". Nancy 1, 1998. http://www.theses.fr/1998NAN10294.
Texto completoTayarani, Jean-Ivan. "Caracterisation des systemes de transport des acides amines neutres et acides dans les capillaires cerebraux isoles de rat : effets des sels de mercure sur ces systemes de transport, protection enzymatique contre les peroxydations dans les capillaires". Paris 7, 1987. http://www.theses.fr/1987PA077060.
Texto completoLapointe, Eric. "Scanner pour tomographie optique diffuse sans contact à canaux de détection dans le domaine temporel à deux bandes de longueur d'onde pour imagerie intrinsèque et par fluorescence sur petit animal". Mémoire, Université de Sherbrooke, 2011. http://savoirs.usherbrooke.ca/handle/11143/1619.
Texto completoGustin, Bernard. "Influence des propriétés viscoélastiques de sondes endotrachéales sur leur interaction avec les voies aériennes supérieures : (élément de définition d'une assurance qualité)". Vandoeuvre-les-Nancy, INPL, 1996. http://www.theses.fr/1996INPL083N.
Texto completoMercklé, Jean. "Stratégies de détection de rupture de modèle appliquées à la recherche et à la localisation des défauts sur des produits sidérurgiques". Nancy 1, 1988. http://www.theses.fr/1988NAN10047.
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