Made available in DSpace on 2014-06-11T19:22:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-05-31Bitstream added on 2014-06-13T18:49:50Z : No. of bitstreams: 1 reis_igm_me_rcla.pdf: 1760261 bytes, checksum: dec7c3739e75a3afb0a688fcc68236aa (MD5) / No modelo de natação para ratos, a associação das intensidades de exercício determinadas por meio da lactacidemia com as suas respectivas sobrecargas são passíveis de crítica, uma vez que a quantificação dos pesos atados ao animal pode não representar efetivamente o esforço real do animal para sua manutenção na superfície da água, devido a esta metodologia sofrer influência da densidade corporal e dos padrões de nado apresentados pelos animais. O principal objetivo desse estudo foi desenvolver um modelo de natação atada para roedores o qual permitiu a determinação direta e em tempo real da força de nado realizada pelo animal e verificar a possível existência de diferentes padrões de nado. Além disso, foi feita a discriminação da densidade corporal em animais controles e induzidos à obesidade, com intuito de destacar consistentemente a influência da flutuabilidade na natação. Foram utilizados 24 rattus norvegicus albinus, machos, com 150 dias de idade, divididos em animais controles e induzidos à obesidade por meio da redução de ninhada somada a uma dieta hiperlipídica. Os animais tiveram a densidade corporal determinada por meio de um aparato de pesagem hidrostática utilizando um sistema de aquisição de dados. Posteriormente todos os ratos foram avaliados no teste de máxima fase estável de lactato adaptado para natação atada. Por meio do modelo experimental de indução a obesidade, foi possível induzir aumento significativo do peso e volume corporal, alem da redução da densidade corporal dos animais no grupo obeso. As avaliações de animais controles e obesos revelaram a influência significativa da densidade corporal na determinação das intensidades de exercício, principalmente quando as cargas foram expressas em valores absolutos. Estudos que fazem uso do modelo de natação para ratos, principalmente de caráter longitudinal... / In the swimming model for rats, the association between the blood lactate concentration with the exercise intensity could be criticized once the workload quantification could not represent effectively the effort performed by the rat to keep himself on the surface, due to it be affected by the body density and the swimming patterns present by the animals. Thus, the mainly objective of this study was develop a apparatus for tethered swimming for rats, that allows the monitoring of swimming force during all exercise time and to verify the existence of different sorts of swimming patterns. 24 male rattus novergicus albinus, with 150 days of age were used, divided in control and obese induced animals by a nest reduction and hyper-lipid diet. All animals had their body density determined by hydrostatic weighing with an acquiring data device. Later the animals were evaluated in maximal lactate steady state test adapted to the tethered swimming. Was possible to induce significant weight and body volume increase in the obese group beside the reduction of the body density. The assessment of control and obese animals reveled significant body density influence in the workload determination, mainly when the workload was expressed in absolute values. Tethered swimming model allowed the investigation of statistic parameters of the data signal, which showed that the signal amplitude varied in function of the intensity, however the dispersion did not. Also the visual analyses of the force kinetic allowed the identification of 4 swimming patterns and the speculation about the reason and consequences of it incidence. Therefore animals that present such swimming patterns which can influence the assessment should be removed from the sample. Studies that make use of the swimming model for rats, mainly those of longitudinal duration or that make use of interventions that may change the animal’s body composition...(Complete abstract click electronic access below)

Les bicouches lipidiques constituent l’architecture socle des membranes biologiques et l’environnement bidimensionnel de leurs protéines. Ancrées sur une interface hydrophile hydratée, ces systèmes conservent leur fluidité et sont localisés durablement près d’un substrat. Dans ce domaine, nous avons développé une stratégie de fonctionnalisation rapide, peu coûteuse et versatile, permettant la formation d’une membrane biomimétique fluide, ancrée sur des substrats conducteurs spécifiquement conçus pour son étude structurale et dynamique. La chimie de surface proposée forme une liaison covalente forte entre le substrat et des molécules commerciales amphiphiles (Brij, etc), utilisées comme système ancre-harpon. L’extrémité hydrophile (coté ancre) possédant un alcool primaire peu réactif est engagée sur une première couche organique par substitution nucléophile. L’autre extrémité hydrophobe (l’harpon) peut s’insérer dans la membrane et la stabiliser. Un mélange adapté, de ces molécules ancre-harpon avec d’autres purement hydrophiles (PEG, etc), apporte l’hydratation et la densité d’ancres nécessaire à l’interface pour maintenir la membrane éloignée du substrat, permettant ainsi l’intégration de protéines et le transport ionique à travers la membrane. Grâce au support conducteur, la dynamique des ions face aux membranes peut être étudiée par spectroscopie d’impédance électrochimique. Sa faible rugosité et semi-transparence permettent aussi l’utilisation de nombreuses autres techniques dont les microscopies optiques, exaltées ou de fluorescence. Localisées sur une électrode, ces bicouches ancrées s’ouvrent également aux applications biotechnologiques. / Lipid bilayers are the structural backbone of biological membranes and provide a two-dimensional environment for proteins. Tethered on a hydrophilic substrate, these biomimetic models are fluid, long-term stable and localized. In this regard, we propose a direct, cheap and versatile strategy of surface functionalization to tether membranes on a substrate adapted to their structural and dynamics study. The process is based on the functionalization of any flat metal thin film by the covalent binding of commercial surfactant molecules (Brij, …) as “anchor-harpoons”-like systems. Most of these molecules possess unresponsive –OH terminated groups on their hydrophilic moiety (anchor) that can bind a first organic layer by nucleophilic substitution. The opposite hydrophobic tail (harpoon) of the molecule can insert into the membrane and make it stable. An ideal mixing ratio of anchor-harpoons molecules with purely hydrophilic ones (PEG, …), provides the required hydration and density of anchors to the interface for tethering fluid membranes away from the substrate. A few nanometers distance enable ionic flows through the membrane and protein inclusion. The substrate conductivity enables studying ion dynamics facing the membrane by means of electrochemical impedance spectroscopy. Flatness and semi-transparency of the conductor opens the route to many other techniques’ including exalted light microscopy or fluorescence. Localized on electrodes, tethered bilayers further provide a biomimetic model and a support for biotechnology applications.

No description available.

Due to the unsustainable space debris environment in Low Earth Orbit, debris objects must be removed to ensure future safe satellite operations. One proposed concept for deorbiting larger space debris objects, such as decommissioned satellites or spent upper rocket stages, is to use a chaser spacecraft connected to the debris object by an elastic tether, but the required technology is immature and there is a lack of flight experience. The inoperable satellite, Envisat, has been chosen as a representative object for controlled re-entry by performing several high thrust burns. The aim of this paper is to develop a control system for the deorbit phase of such a mission. Models of the spacecraft dynamics, the tether, and sensors are developed to create a simulator. Two different tether models are considered: the massless model and the lumped mass model. A switched linear-quadratic-Gaussian (LQG) controller is designed to control the relative position of the debris object, and a switched proportional-integral-derivative (PID) controller is designed for attitude control. Feedforward compensation is used to counteract the couplings between relative position and attitude dynamics. An analysis of the system suggests that the tether should be designed in regard to the control system and it is found that the lumped mass model comes with higher cost than reward compared to the massless tether model in this case. Simulations show that the control system is able to control the system under the influence of modeling errors during a multi-burn deorbit strategy and even though more extensive models are suggested to enable assessment of the feasibility to perform this mission in reality, this study has resulted in extensive knowledge and valuable progress in the technical development. / En ökande mängd rymdskrot har lett till en ohållbar miljö i låga omloppsbanor och föremål måste nu tas bort för att säkerställa framtida satellitverksamhet. En föreslagen metod för att avlägsna större skrotföremål, såsom avvecklade satelliter och använda övre raketsteg, är att koppla en jagande rymdfarkost till föremålet med en elastisk lina. Dock är den teknik som behövs inte mogen och det finns en brist på praktisk erfarenhet. Den obrukbara satelliten Envisat har valts som representativt objekt för kontrollerat återinträde genom flera perigeumsänkande raketmanövrar. Syftet med detta arbete är att utveckla ett system för att kontrollera de två sammankopplade rymdfarkosterna under avlägsningsfasen under ett sådant uppdrag. Modeller för farkosternas dynamik, den sammankopplande linan och sensorer byggs för att utveckla en simulator. Två olika modeller för linan undersöks: den masslösa modellen och den klumpade nodmassmodellen. En omkopplande regulator designas genom minimering av kvadratiska kriterier för att kontrollera skrotföremålets relativa position till den jagande farkosten. Vidare designas en omkopplande proportionerlig-integrerande-deriverande (PID) regulator för att reglera pekningen hos den jagande farkosten. Kompensering genom framkoppling används för att motverka de korskopplingar som förekommer mellan translations- och rotationsdynamiken. En analys av systemet visar att linan bör designas med reglersystemet i åtanke och det framkommer att nackdelarna överväger fördelarna för den klumpade nodmassmodellen jämfört med den masslösa modellen. Simuleringar visar att reglersystemet klarar att kontrollera systemet under ett scenario med flera manövrar och under inverkan av modellfel. Även om mer omfattande modeller föreslås för att möjliggöra en fullständig bedömning av genomförbarheten för detta uppdrag så har denna studie resulterat i en omfattande kunskapsvinst och värdefulla framgångar i det tekniska utvecklingsarbetet.

Despite the central role of IFNγ in vitiligo pathogenesis, systemic IFNγ neutralization is an impractical treatment option due to strong immunosuppression. However, most vitiligo patients present with less than 20% affected body surface area, which provides an opportunity for localized treatments that avoid systemic side effects. After identifying keratinocytes as key cells that amplify IFNγ signaling during vitiligo, I hypothesized that tethering an IFNγ neutralizing antibody to keratinocytes would limit anti-IFNγ effects to the treated skin for the localized treatment. To that end, I developed a bispecific antibody (BsAb) capable of blocking IFNγ signaling while binding to desmoglein expressed by keratinocytes. I characterized the effect of the BsAb in vitro, ex vivo, and in a mouse model of vitiligo. SPECT/CT biodistribution and serum assays after local footpad injection revealed that the BsAb had improved skin retention, faster elimination from the blood, and less systemic IFNγ inhibition than the non-tethered version. Furthermore, the BsAb conferred localized protection almost exclusively to the treated footpad during vitiligo that was not possible by local injection of the non-tethered anti-IFNγ antibody. Thus, keratinocyte-tethering proved effective while significantly diminishing off-tissue effects of IFNγ blockade, offering a new treatment strategy for localized skin diseases, including vitiligo.

Indiana University-Purdue University Indianapolis (IUPUI) / Plasma membranes are complex supramolecular assemblies comprised of lipids and membrane proteins. Both types of membrane constituents are organized in highly dynamic patches with profound impact on membrane functionality, illustrating the functional importance of plasma membrane fluidity. Exemplary, dynamic processes of membrane protein oligomerization and distribution are of physiological and pathological importance. However, due to the complexity of the plasma membrane, the underlying regulatory mechanisms of membrane protein organization and distribution remain elusive. To address this shortcoming, in this thesis work, different mechanisms of dynamic membrane protein assembly and distribution are examined in a polymer-tethered lipid bilayer system using comple-mentary confocal optical detection techniques, including 2D confocal imaging and single molecule-sensitive confocal fluorescence intensity analysis methods [fluorescence correlation spectroscopy (FCS) autocorrelation analysis and photon counting histogram (PCH) method]. Specifically, this complementary methodology was applied to investigate mechanisms of membrane protein assembly and distribution, which are of significance in the areas of membrane biophysics and cellular mechanics. From the membrane biophysics perspective, the role of lipid heterogeneities in the distribution and function of membrane proteins in the plasma membrane has been a long-standing problem. One of the most well-known membrane heterogeneities are known as lipid rafts, which are domains enriched in sphingolipids and cholesterol (CHOL). A hallmark of lipid rafts is that they are important regulators of membrane protein distribution and function in the plasma membrane. Unfortunately, progress in deciphering the mechanisms of raft-mediated regulation of membrane protein distribution has been sluggish, largely due to the small size and transient nature of raft domains in cellular membranes. To overcome this challenge, the current thesis explored the distribution and oligomerization of membrane proteins in raft-mimicking lipid mixtures, which form stable coexisting CHOL-enriched and CHOL-deficient lipid domains of micron-size, which can easily be visualized using optical microscopy techniques. In particular, model membrane experiments were designed, which provided insight into the role of membrane CHOL level versus binding of native ligands on the oligomerization state and distribution of GPI-anchored urokinase plasminogen activator receptor (uPAR) and the transmembrane protein αvβ3 integrin. Experiments on uPAR showed that receptor oligomerization and raft sequestration are predominantly influenced by the binding of natural ligands, but are largely independent of CHOL level changes. In contrast, through a presumably different mechanism, the sequestration of αvβ3 integrin in raft-mimicking lipid mixtures is dependent on both ligand binding and CHOL content changes without altering protein oligomerization state. In addition, the significance of membrane-embedded ligands as regulators of integrin sequestration in raft-mimicking lipid mixtures was explored. One set of experiments showed that ganglioside GM3 induces dimerization of α5β1 integrins in a CHOL-free lipid bilayer, while addition of CHOL suppresses such a dimerization process. Furthermore, GM3 was found to recruit α5β1 integrin into CHOL-enriched domains, illustrating the potential sig-nificance of GM3 as a membrane-associated ligand of α5β1 integrin. Similarly, uPAR was observed to form complexes with αvβ3 integrin in a CHOL dependent manner, thereby causing the translocation of the complex into CHOL-enriched domains. Moreover, using a newly developed dual color FCS and PCH assay, the composition of uPAR and integrin within complexes was determined for the first time. From the perspective of cell mechanics, the characterization of the dynamic assembly of membrane proteins during formation of cell adhesions represents an important scientific problem. Cell adhesions play an important role as force transducers of cellular contractile forces. They may be formed between cell and extracellular matrix, through integrin-based focal adhesions, as well as between different cells, through cadherin-based adherens junctions (AJs). Importantly, both types of cell adhesions act as sensitive force sensors, which change their size and shape in response to external mechanical signals. Traditionally, the correlation between adhesion linker assembly and external mechanical cues was investigated by employing polymeric substrates of adjustable substrate stiffness containing covalently attached linkers. Such systems are well suited to mimic the mechanosensitive assembly of focal adhesions (FAs), but fail to replicate the rich dynamics of cell-cell linkages, such as treadmilling of adherens junctions, during cellular force sensing. To overcome this limitation, the 2D confocal imaging methodology was applied to investigate the dynamic assembly of N-cadherin-chimera on the surface of a polymer-tethered lipid multi-bilayer in the presence of plated cells. Here, the N-cadherin chimera-functionalized polymer-tethered lipid bilayer acts as a cell surface-mimicking cell substrate, which: (i) allows the adjustment of substrate stiffness by changing the degree of bilayer stacking and (ii) enables the free assembly of N-cadherin chimera linkers into clusters underneath migrating cells, thereby forming highly dynamic cell-substrate linkages with remarkable parallels to adherens junctions. By applying the confocal methodology, the dynamic assembly of dye-labeled N-cadherin chimera into clusters was monitored underneath adhered cells. Moreover, the long-range mobility of N-cadherin chimera clusters was analyzed by tracking the cluster positions over time using a MATLAB-based multiple-particle tracking method. Disruption of the cytoskeleton organization of plated cells confirmed the disassembly of N-cadherin chimera clusters, emphasizing the important role of the cytoskeleton of migrating cells during formation of cadherin-based cell-substrate linkages. Size and dynamics of N-cadherin chimera clusters were also analyzed as a function of substrate stiffness.

The tethered balloon system BELUGA (BalloonbornE moduLar Utility for profilinG the lower Atmosphere) was operated in spring 2022 at the AWIPEV research station (Ny-Ålesund, Svalbard). In-situ profiles of thermodynamic parameters, thermalinfrared radiation, aerosol particle concentrations, and turbulence, were measured and analyzed. Additionally, samples of ice-nucleating particles were collected at various heights. In combination with previous BELUGA datasets, measurements from this campaign provide a solid base for studying the vertical profiles of the radiative energy budget and heating rates in different atmospheric states in the Arctic lower troposphere. Here, example thermal-infrared radiation profiles are presented for a period of persisting cloudless conditions related to a series of marine cold air outbreaks in late March/early April. Measurements in clouds are analyzed for a developing cloud observed on 6 May and display the impact of cloudiness on radiation profiles. / Das Fesselballonsystem BELUGA (BalloonbornE moduLar Utility for profilinG the lowerAtmosphere) wurde im Frühjahr 2022 an der Forschungsstation AWIPEVStation (Ny-Ålesund, Svalbard) eingesetzt. In-situ-Profile von thermodynamischen Parametern, terrestrische Strahlung, Aerosolpartikelkonzentrationen und Turbulenz wurden gemessen und ausgewertet. Zusätzlich wurden in verschiedenen Höhen Proben von eiskeimbildenden Partikeln gesammelt. In Kombination mit früheren BELUGA Messungen zu anderen Jahreszeiten und an anderen arktischen Messstandorten bieten die Messungen in Ny-Ålesund eine Grundlage fürweitereUntersuchungen des Strahlungsenergiehaushalts und des Einflusses vonWolken auf atmosphärische Heizraten. Profile der Strahlungsbilanz werden für eine anhaltende Kälteperiode zwischen Ende März bis Anfang April 2022 vorgestellt. Über diesen Zeitraum herrschten vor allem wolkenlose Bedingungen. Weitere Beobachtungen unter einer sich entwickelnden Wolkendecke am 6. Mai 2022 zeigen den Einfluss der Bewölkung auf die Strahlungsprofile.

No description available.

Les protéines membranaires intégrales jouent un rôle essentiel dans le maintien de l’intégrité cellulaire (transports d’ions et de nutriments, transduction de signal, interaction cellule-cellule). Afin de les étudier, ces protéines doivent être produites in vitro. La production classique de ces protéines membranaires intégrales dans des microorganismes présente de nombreuses difficultés liées à leur structure complexe mais aussi à des problèmes de toxicité, empêchant la production de nombre d’entre elles. En outre, pour être produites efficacement, ces protéines ont besoin d’un environnement amphiphile. Dans cette thèse, afin de pallier à ces difficultés, nous avons d’une part utilisé un système d’expression protéique acellulaire, non affecté par la physiologie des cellules vivantes. En outre, nous avons choisi de les intégrer dans des bicouches lipidiques planes reconstituées artificiellement. Dans une première partie, nous avons mis au point l’intégration d’une protéine membranaire intégrale formant un pore, l’alpha hémolysine, dans une bicouche lipidique supportée. Certaines protéines nécessitant un espace plus important de part etd’autre de la membrane, nous avons, dans une seconde partie, développé une bicouche lipidique espacée et ancrée par fusion de liposomes sur des surfaces d’or. Nous démontrons qu’il est possible d’y incorporer des protéines membranaires de type Aquaporine Z sous certaines conditions. Dans une troisième partie, dédiée à la formation de membranes biomimétiques utilisant des molécules lipidiques provenant d’Escherichia coli, nous montrons que la modification de la composition membranaire ne semble pas avoir d’incidence sur l’incorporation de protéines. Enfin, dans une dernière partie, nous avons réalisé des premiers essais d’insertion de protéines membranaires, de type alpha hémolysine, dans des bicouches suspendues afin de montrer que ces protéines produites par le système d’expression acellulaire sont fonctionnelles. / Integral membrane proteins play an essential role in the cell integrity preservation (transport of nutrients and ions, signal transduction, cell-cell interaction). In order to study these proteins, they have to be produced in vitro. Classical production of integral membrane proteins in microorganisms present many difficulties associated with their complex structure and also toxicity problems, preventing production of many of them. Moreover, to be efficiently produced, these proteins require an amphiphilic environment. In order to overcome these difficulties, we used a cell-free protein expression system, unaffected by the physiology ofliving cells. In addition, we chose to integrate them into artificial planar lipid bilayers. In a first part, we have developed the integration of an integral membrane protein forming a pore, the alpha hemolysin, in a supported lipid bilayer. Some proteins require more space on each side of the membrane, therefore in a second part, we have developed a tethered lipid bilayer membrane by liposome fusion on gold surfaces. We demonstrate that it is possible to incorporate membrane protein Aquaporin Z under certain conditions. The third part is dedicated to the formation of biomimetic membranes using lipid molecules from Escherichiacoli, we show that the membrane composition do not affect the protein incorporation. Finally, we have tested alpha hemolysin membrane proteins insertion in suspended lipid bilayers membranes to show that these proteins produced by the cell-free expression system are functional.

Cette thèse se concentre sur les robots aériens autonomes qui interagissent avec l’environnement et en particulier sur la conception de nouvelles méthodes de commande et de planification de mouvement pour tels systèmes. De nos jours, les véhicules aériens autonomes sont de plus en plus utilisés dans des nombreux domaines d’application, mais ils viennent utilisés surtout comme des simples capteurs. Au vu de ça, les défis majeurs dans le domaine de l’interaction physique aérienne, est aujourd’hui d’aller au-delà de cette application limitée, et d’exploiter entièrement les capacités des robots aériens afin d’interagir avec l’environnement. Dans le but de réaliser cet objectif, cette thèse considère l’analyse d’une classe spécifique de systèmes aériens interagissant avec l’environnement : les véhicules aériens attachés avec des câbles ou des bars. Ce travail se concentre sur l’analyse formelle et minutieuse de véhicules aériens attachés, en allant du contrôle et l’évaluation d’état à la planification du mouvement. Nous avons examiné notamment la platitude différentielle du système, trouvant deux sorties plate possibles qui révèlent des nouvelles capacités de tel système pour l’interaction physiques. En plus, poussé par l’intérêt pour l’interaction physique aérienne d’A à Z, nous avons abordés des problèmes supplémentaires liés à la conception, au contrôle et à la planification du mouvement pour des manipulateurs aériens. / This thesis focuses on the study of autonomous aerial robots interacting with the surrounding environment, and in particular on the design of new control and motion planning methods for such systems. Nowadays, autonomous aerial vehicles are extensively employed in many fields of application but mostly as autonomously moving sensors. On the other hand, in the recent field of aerial physical interaction, the goal is to go beyond sensing-only applications and fully exploit the aerial robots capabilities in order to interact with the environment. With the aim of achieving this goal, this thesis considers the analysis of a particular class of aerial robots interacting with the environment: tethered aerial vehicles. This work focuses on the thorough formal analysis of tethered aerial vehicles ranging from control and state estimation to motion planning. In particular, the differential flatness property of the system is investigated, finding two possible flat outputs that reveal new capabilities of such system for the physical interaction. The theoretical results were finally employed to solve the challenging problem of landing and takeoff on/from a sloped surface. In addition, moved by the interest on aerial physical interaction from A to Z, we addressed supplementary problems related to the design, control and motion planning for aerial manipulators.