Thèses sur le sujet « Transport and localization »
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Kuzovkov, Vladimir, et Niessen Wolfgang von. « Anderson localization and generalized diffusion ». Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-195390.
Kuzovkov, Vladimir, et Niessen Wolfgang von. « Anderson localization and generalized diffusion ». Diffusion fundamentals 2 (2005) 26, S. 1-2, 2005. https://ul.qucosa.de/id/qucosa%3A14355.
Fung, Alex Weng Pui. « Localization transport in granular and nanoporous carbon systems ». Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/34088.
Bjorgaard, Josiah August. « Exciton Diffusion, Transport, and Localization in Conjugated Polymers ». Diss., North Dakota State University, 2013. https://hdl.handle.net/10365/27196.
Kurzidim, Jan, Daniele Coslovich et Gerhard Kahl. « Localization and glass formation of fluids confined in porous matrices ». Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-191691.
Real, Elgueda Bastián Maximiliano. « Transport and driven-dissipative localization in exciton-polariton lattices ». Electronic Thesis or Diss., Université de Lille (2022-....), 2022. http://www.theses.fr/2022ULILR025.
The simulation of lattice Hamiltonians in photonic platforms has been enlightening in the understanding of novel transport and localization properties in the context of solid-state physics. In particular, exciton-polaritons provide a versatile system to investigate these properties in lattices with intriguing band structures in the presence of gain and loss, and particle interactions. Polaritons are hybrid light-matter quasiparticles arising from the strong coupling between photons and excitons in semiconductor microcavities, whose properties can be directly accessed in photoluminescence experiments. In this thesis, we firstly study the features of strained honeycomb lattices made of coupled polariton resonators having high photonic content. In a critically strained lattice, we evidence both a semi-Dirac transport and an anisotropic localization of photons. Secondly, we show that a judicious driving in lattices of lossy resonators allows the appearance of novel localized modes. Using polariton lattices driven resonantly with several optical beams, we demonstrate the localization of light in at-will geometries down to a single site. Finally, we take advantage of the polarization-dependent polariton interaction to demonstrate an optical Zeeman-like effect in a single micropillar. In combination with optical spin-orbit coupling inherent to semiconductor microstructures, the interaction-induced Zeeman effect results in emission of vortex beams with a well-defined chirality. This thesis brings to light the power of polariton platforms to study lattice Hamiltonians with unprecedented properties and it also provides a first step towards the fully-optical generation of topological phases in lattices
Gómez, Rivas Jaime. « Light in strongly scattering semiconductors diffuse transport and Anderson localization / ». [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2002. http://dare.uva.nl/document/63879.
Coslovich, Daniele, Dieter Schwanzer et Gerhard Kahl. « Diffusion-localization and liquid-glass transitions of a colloidal fluid in porous confinement ». Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-190390.
Kurzidim, Jan, Daniele Coslovich et Gerhard Kahl. « Localization and glass formation of fluids confined in porous matrices ». Diffusion fundamentals 11 (2009) 105, S. 1-2, 2009. https://ul.qucosa.de/id/qucosa%3A14079.
Chitale, Chaitanya S. « Spatial Characterization of Protein Localization Patterns ». The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1282088474.
Römer, Rudolf. « From localization to delocalization : numerical studies of transport in disordered systems ». Doctoral thesis, Universitätsbibliothek Chemnitz, 2000. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200000568.
Yin, Liang. « Superconductivity in quasi-two-dimensional organic conductors : dissipation, transport and localization ». Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444946.
Nguyen, Thi Thuong. « Magneto-transport and localization in disordered systems with local superconductive attraction ». Doctoral thesis, SISSA, 2016. http://hdl.handle.net/20.500.11767/4882.
Coslovich, Daniele, Dieter Schwanzer et Gerhard Kahl. « Diffusion-localization and liquid-glass transitions of a colloidal fluid in porous confinement ». Diffusion fundamentals 11 (2009) 58, S. 1-2, 2009. https://ul.qucosa.de/id/qucosa%3A14023.
Snyder, Kenneth A. « Energy localization and transport in binary isotopically disordered Fermi-Pasta-Ulam chains ». College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2643.
Thesis research directed by: Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
Wilson, Jonathan Mark. « The fish branchial epithelium, an immunological approach to ion transport protein localization ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0018/NQ48737.pdf.
Körber, Martin Julius. « Phase-Space Localization of Chaotic Resonance States due to Partial Transport Barriers ». Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-218817.
Gillespie, Doreen. « The role of homeless in RNA transport and localization during Drosophila oogenesis / ». Thesis, Connect to this title online ; UW restricted, 1996. http://hdl.handle.net/1773/10305.
Breitkreuz, Kevin Edmund. « Subcellular localization of gamma-aminobutyrate metabolism and transport of gamma-aminobutyrate in plants ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0004/NQ40365.pdf.
Dunst, Sebastian. « Systematic characterization of Rab GTPase cell type expression and subcellular localization in Drosophila melanogaster ». Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-165234.
Evers, Martin [Verfasser]. « Two antagonizing aspects of spin transport : spin-wave localization and spin superfluidity / Martin Evers ». Konstanz : KOPS Universität Konstanz, 2019. http://d-nb.info/1230323309/34.
Thébaud, Simon. « Electron and phonon transport in disordered thermoelectric materials : dimensional confinement, resonant scattering and localization ». Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1168/document.
Over the past decades, the increasingly pressing need for clean energy sources and the realization that a huge proportion of the world energy consumption is wasted in heat have prompted great interest in developing efficient thermoelectric generation modules. These devices could harvest waste heat from industrial processes or other sources, turning a temperature gradient into a voltage through the Seebeck effect. Efficient thermoelectric materials should exhibit a low thermal conductivity, a high electrical conductivity and a high Seebeck coefficient. Simultaneously optimizing these parameters is a great challenge of condensed matter physics and materials science. With a view to enhance the thermoelectric properties of several promising materials, we explore several strategies in which defects (atomic substitutions, vacancies…), disorder and dimensional confinement play a crucial role. We perform density functional theory calculations and projections on Wannier orbitals to construct realistic Hamiltonians and dynamical matrices describing their electronic and vibrational structure in real space. These parameters are then used to compute the thermoelectric transport properties using the Kubo formalism, the Boltzmann transport equation, the Landauer formalism, and the Chebyshev polynomial Green's function method that allows for an exact treatment of disorder. We investigate the electronic transport properties and thermoelectric performances of two promising materials for high-temperature power generation, strontium titanate and rutile titanium dioxide. Comparison of our predictions with a wealth of experimental data yields a very good agreement. We show that the increase of the Seebeck coefficient observed in strontium titanate superlayers, until now attributed to quantum confinement effects, is in fact well explained assuming delocalized electrons. The general effects of resonant states on electronic transport are explored in a model study, showing a sixfold increase of the thermoelectric performances. The particular case of strontium titanate is then examined, and localization effects are shown to destroy the performances if Vanadium atoms are introduced as resonant impurities. The influence of defects in two-dimensional materials is investigated. Contrary to adatoms, substitutions in transition metal dichalcogenides are shown to localize the charge carriers. We study the effect of vacancies on phonon transport in graphene, and determine the phonon-vacancy scattering rate. Comparison with thermal conductivity data for irradiated and finite-size graphene samples yields a very good agreement between theory and experiments
Torelli, Daniele. « Functionals for TDDFT description of electron transport in nanostructures ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/11143/.
Alvestad, Rachel Marie. « Phosphorylation and subcellular localization of NMDA receptors : modulation by ethanol / ». Connect to full text via ProQuest. IP filtered, 2005.
Typescript. Includes bibliographical references (leaves 145-170). Free to UCDHSC affiliates. Online version available via ProQuest Digital Dissertations;
Müller, Kerstin [Verfasser]. « Localization and transport of ribosomes in axons of the mammalian PNS and CNS / Kerstin Müller ». Mainz : Universitätsbibliothek Mainz, 2017. http://d-nb.info/1138948543/34.
CANDELORI, ANNALISA. « Protein transport into the nucleus : characterization of nuclear localization signals in the protozoan ciliate Euplotes ». Doctoral thesis, Università degli Studi di Camerino, 2013. http://hdl.handle.net/11581/401706.
Hahn, Wiebke. « Disorder-induced localization effects in nitride semiconductor compounds and devices ». Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX049.
There are growing indications that alloy disorder controls to a large extent the electrical and optical properties of semiconductor compounds. In nitride ternary alloys, intrinsic compositional disorder, resulting from the random distribution of atoms on the crystal lattice, induces strong electronic localization effects. These disorder-induced localization effects are suspected to have a major impact on the performances of nitride-based light-emitting diodes (LEDs). It is therefore of primary importance to address this issue as huge energy savings are concerned. However, the investigation of alloy disorder effects is not trivial since the typical disorder length scale is in the nm range.During this thesis, we developed a scanning tunneling electroluminescence (STL) spectroscopy experiment to detect the radiative recombination of electrons locally injected by a scanning tunneling microscope tip in a GaN/InGaN/GaN quantum well, similar to those present in the active region of LEDs. Narrow emission peaks are detected which are characteristic of emission from single localized states. Fluctuations in the line shape of the local electroluminescence are observed at the scale of a few nm which evidence localization effects induced by alloy disorder. These experimental results are in good agreement with the so-called localization landscape theory which provides an effective confining potential map for the carriers exhibiting nanometer size localization regions
Muller, Kilian. « Coherent transport of ultracold atoms in disordered potentials : Manipulation of time-reversal symmetry in weak localization experiments ». Thesis, Palaiseau, Institut d'optique théorique et appliquée, 2014. http://www.theses.fr/2014IOTA0013/document.
In this manuscript the coherence effects of wave propagation in disordered potentials is studied. Our experiment uses ultracold atoms as a probe, a system allowing for a very good control over parameters such as the dimensionality, interactions, initial velocity of the atoms, and the potential landscape. Exploiting this flexibility we were able to perform experiments in the strongly and the weakly localized regime. In the former the 3D expansion of a BEC was monitored in real space, resulting in the observation of 3D Anderson localization with a maximum localized fraction of about 20%. In the latter the atoms were launched into a quasi-2D disorder with a well defined initial velocity. Monitoring the momentum space distribution the mean scattering time and the transport time can be directly measured, and coherent backscattering (CBS) is clearly visible as a peak in the backwards direction. In a first set of experiments the evolution of the CBS amplitude and width were recorded and found to be in good agreement with theory. Microscopically, CBS stems from the constructive interference of time-reversed multiply scattered paths. In a second set of CBS experiments we manipulated the time-reversal symmetry (TRS) of the wave propagation. A surgical dephasing was introduced via a shortly pulsed gradient field, which brakes TRS and suppresses CBS except for a brief moment, when a revival of CBS is observed. This novel effect showcases explicitly the role of coherence and TRS in Coherent Backscattering and weak localization
Hultell, (Andersson) Magnus. « Electron-lattice dynamics in π-conjugated systems ». Doctoral thesis, Linköpings universitet, Beräkningsfysik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-12590.
I dagens samhälle är elektroniken ett allt viktigare och större inslag i vår vardag. Vi ser på TV, talar i mobiltelefoner, och arbetar på datorer. I hjärtat av denna teknologi finner vi diskreta komponenter och integrerade kretsar utformade främst för att styra strömmen av elektroner genom halvledande material. Traditionellt sett har kisel eller olika former av legeringar använts som det aktiva materialet i dessa komponenter och kretsar, men under de senaste 20 åren har såväl transistorer som solceller och lysdioder realiserats där det aktiva materialet är organiskt, d.v.s., kolbaserat.Vi befinner oss för tillfället mitt uppe i det kommersiella genombrottet för organisk elektronik. Redan idag säljs många MP3-spelare och mobiltelefoner med små skärmar där varje pixelelementen utgörs av organiska ljusemitterande dioder (OLEDs), men teknologin håller redan på att introduceras i mer storskaliga produkter som datorskärmar och TV-apparater som därigenom skulle kunna göras energieffektivare, tunnare, flexiblare och på sikt också billigare. Andra tekniska tillämpningsområden för organisk elektronik som förutspås en lysande framtid är RFID-märkning, organiska solceller, och elektronik tryckt på papper, men även smarta textiler och bioelektronik har stor utvecklingspotential.Den kanske största utmaningen kvarstår dock, att skapa elektroniska kretsar och komponenter uppbyggda kring enskilda molekyler, s.k. molekylär elektronik. Mycket snart närmar vi oss den fysikaliska gränsen för hur små komponenter som vi kan realisera med traditionella icke-organiska material som kisel och en stor drivkraft bakom forskningen på halvledande organiska material har varit just visionen om molekylär elektronik som inte är mer än några miljondelars milimeter stora. För detta ändamål krävs en mycket nogrann kontroll av tillverkningsprocesserna liksom en detaljförståelse för hur molekylerna leder ström och hur denna förmåga kan manipuleras för att realisera såväl traditionella som nya komponenter.I denna avhandling presenteras en översikt av den fysik som möjliggör ledningsförmåga hos särskilda klasser av organiska material, s.k. π-konjugerade system, samt de forskningsresultat som utgör mitt bidrag till denna disciplin. En av utmaningarna på området är den komplexitet som de organiska materialen erbjuder: laddningsprocesserna påverkas nämligen av en rad olika faktorer såsom laddningstäthet, temperatur, pålagd spänning, samt molekylernas former och inbördes struktur. I detta arbete har jag utifrån en vidareutveckling av existerande modeller genom numeriska datasimuleringar undersökt effekten av de senare tre faktorerna på elektronstrukturen, laddnigstransporten och energidissipation i denna klass av material.
Center of Organic Electronics (COE)
Paulin, Guillaume. « Transport électronique et Verres de Spins ». Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2010. http://tel.archives-ouvertes.fr/tel-00556836.
Stellin, Filippo. « Anderson localization in interacting quantum systems ». Thesis, Université de Paris (2019-....), 2020. http://www.theses.fr/2020UNIP7004.
In this thesis we theoretically investigate the behaviour of quantum particles (electrons, atoms, photons, etc.) moving in a random medium and undergoing Anderson localization. For noninteractingparticles, the energy spectrum can possess one or more critical points, where the nature of the single-particle wavefunctions changes from extended to localized leading to a undergoes a metal-insulator phase transition, also known as Anderson transition.A fundamental question is whether and how Anderson transitions survive in interacting quantum systems. Here we study a minimal model of two particles moving in a disordered lattice and subject to short-range mutual interactions. By combining large-scale numerics with Green’s functions techniques, we show that two-particle Anderson transitions do occur in three dimensions and explore the phase diagram in the space of energy, disorder and interaction strength. The latter presents a rich structure, characterized by a doubly reentrant behavior, caused by the competition between scattering and bound states of the pair. We also show that previous claims of 2D Anderson transitions of the pair are essentially due to finite-size effects.A second problem that we address in this thesis is the occurrence of 2D metal-insulator transitions for a single particle in the presence of a spatially correlated potential and subject to spin-orbit interactions, described by Rashba-Dresselhaus couplings. We illustrate that, irrespective of the properties of the disorder, there is a regime where the critical energy depends linearly on the disorder strength. The slope and the intercept are studied in the vicinity of the spin-helix point, where the SU(2) symmetry is restored and the 2D metal-insulator transition disappears
Lorenzo, Moldero Ivan. « Localization and regulation of trpv4 channels in CILIATED epithelia ». Doctoral thesis, Universitat Pompeu Fabra, 2008. http://hdl.handle.net/10803/7185.
Clearance of mucus and pathogenic agents from lungs and the transport of gametes and embryos in the female reproductive organs are key functions of ciliated epithelia such as those present in the airways and the oviduct. The rate of mucociliary transport is a function of ciliary beat frequency (CBF) and this, in turn, is increased by increases in intracellular calcium. Transient potential vanilloid 4 (TRPV4)cation channel mediates Ca2+ influx in response to mechanical and osmotic stimuli. TRPV4 expression in ciliated epithelia from airways and oviduct is confirmed by immunofluorescence localization of the channel at the apical membrane of the polarized ciliated epithelia, where the Ca2+ signalling is required for CBF regulation. Ciliated tracheal cells from TRPV4-/-mice show no TRPV4 expression, neither increases in intracellular Ca2+ and CBF in response to the TRPV4-specific activator 4α- phorbol 12,13- idecanoate (4α-PDD), and reduced responses to mild temperatures (~25ºC - 38ºC), another TRPV4-activating stimulus. TRPV4 gating by high viscous loads and hypotonicity depends on phospholipase A2 (PLA2) pathway activation and subsequent production of epoxyeicosatrienoic acid (EET). Under conditions of low PLA2 activation, mechanical and hypotonic stimuli use extracellular ATP release-mediated activation of phospholipase C (PLC)-inositol triphosphate(IP3)signalling to support TRPV4 gating. We describe that IP3, without being an agonist itself, sensitizes TRPV4 to EET activation. Besides, the functional coupling between plasma membrane TRPV4 channels and IP3 receptors (IP3R) is required to initiate and maintain the cellular oscillatory Ca2+ signal triggered by high viscous loads and hypotonic stimuli. One of the main CBF activators, adenosine-5'-triphosphate (ATP), triggers both Ca2+ release from intracellular Ca2+ stores and Ca2+ entry. Interestingly, TRPV4 contributes to ATP-induced increase in CBF. Furthermore, our work implicates TRPV4 channel exclusively in receptor-operated Ca2+ entry. Collectively, this PhD thesis shows the role of TRPV4 channels coupling physiologically relevant mechanical, hypotonic and chemical stimuli to CBF regulation in motile ciliary epithelia.
Ivanov, Ruslan. « Impact of carrier localization on recombination in InGaN quantum wells with nonbasal crystallographic orientations ». Doctoral thesis, KTH, Optik och Fotonik, OFO, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-214599.
QC 20170919
Clark, Jennifer L. « Localization of Insulin Receptor Substrate-2 in Breast Cancer : A Dissertation ». eScholarship@UMMS, 2012. https://escholarship.umassmed.edu/gsbs_diss/587.
Hong, Sung-Yong. « Analysis of transport and sub-cellular localization of aflatoxin biosynthetic enzymes, ver-1 and nor-1, using EGFP fusions in Aspergillus parasiticus ». Diss., Connect to online resource - MSU authorized users, 2007.
Title from PDF t.p. (viewed on Apr. 16, 2009) Includes bibliographical references (p. 273-296). Also issued in print.
Sarma, Ashapurna. « Circadian Timing of Curcumin Efficacy and Nuclear Transport Properties of Cancer Cells ». Bowling Green State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1447971823.
Perul, Johan. « Localisation autonome par apprentissage des dynamiques de déplacement en transport multimodal ». Thesis, Ecole centrale de Nantes, 2020. http://www.theses.fr/2020ECDN0021.
The growing development of smart objects offers new opportunities for locating the connected traveller. However, tracking the trajectory of the pedestrian remains problematic and navigation applications do not offer to track the traveller's trajectory on a multimodal level in an autonomous way. This work focuses on the implementation of a single solution able to locate the user according to different travel modes and whatever the environment, using inertial, magnetic and GNSS sensors. In a first step, a new method for locating the cyclist is implemented. GNSS phase measurements are used to correct the velocity vector by time differences and the motion direction is constrained using inertial signals. These elements were used in a second step and adapted to implement a new method of pedestrian localization with a handheld sensor. The PDR approach, which is an inertial dead reckoning navigation technique, is parameterized in an extended Kalman filter. An innovative update merging the device attitude estimation and a statistical estimation of the walking direction allows to correct the walking heading estimation and obtain a consistent and smoothed estimation. GNSS measurements are used to correct speed vector, orientation, step length and absolute position. Finally, a multimodal approach is proposed and the management of transitions between the different algorithms, assisted by the use of an innovative sensor, is studied. Multimodal experimental validations in real conditions are conducted to analyze the estimation performances of the proposed solution
Olsen, Daniel S. « Nuclear BMP2 and the Immune Response ». BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/4171.
Körber, Martin Julius [Verfasser], Roland [Akademischer Betreuer] [Gutachter] Ketzmerick et Henning [Gutachter] Schomerus. « Phase-Space Localization of Chaotic Resonance States due to Partial Transport Barriers / Martin Julius Körber ; Gutachter : Roland Ketzmerick, Henning Schomerus ; Betreuer : Roland Ketzmerick ». Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://d-nb.info/1125851031/34.
Kennedy, Kathleen Anne. « Assembly of the maltose transport complex of Escherichia coli and the dimerization, localization, and functional domain structure of its ATP-binding subunit, MalK / ». Thesis, Connect to this title online ; UW restricted, 1999. http://hdl.handle.net/1773/11504.
Chauhan, Vinita Singh. « Molecular characterization of severe acute respiratory syndrome (SARS) coronavirus - nucleocapsid protein ». Diss., Manhattan, Kan. : Kansas State University, 2006. http://hdl.handle.net/2097/152.
Liu, Xiya. « Mesoscopic effects in ferromagnetic materials ». Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24669.
Committee Chair: Davidovic, Dragomir; Committee Member: Citrin, David; Committee Member: Kindermann, Markus; Committee Member: Marchenkov, Alexei; Committee Member: Riedo, Elisa
Sapienza, Riccardo. « Matériaux nano photoniques : transport anisotrope et oscillations de Bloch optiques ». Phd thesis, Université Pierre et Marie Curie - Paris VI, 2005. http://tel.archives-ouvertes.fr/tel-00009751.
nano-matériaux diélectriques complexes est un sujet de recherche
riche et fascinant, tant pour ses implications fondamentales que
pour son impact technologique. Dans cette thèse, nous étudions les
effets d'interférence de la lumière dans les systèmes photoniques
quasi-ordonnés.
Dans des milieux diélectriques aléatoires, on peut décrire le
mouvement des photons mutiplement diffusés par une marche
aléatoire de diffuseur en diffuseur: la plupart des effets
d'interférence se moyennent alors à zéro, mais certains survivent
quand même au désordre et induisent des phénomènes non-triviaux.
Dans des milieux qui diffusent très fortement, la lumière pourrait
même devenir localisée et aucun transport ne serait possible. Dans
les milieux ordonnés, la périodicité conduit à des lois de
dispersion inhabituelles où les effect collectifs d'interférence
dominent: le transport est fortement dépendant de la fréquence, il
peut être sensiblement augmenté (interférences constructives) ou
complètement inhibé (interférences destructives).
Notre compréhension de la propagation des ondes lumineuses dans
les milieux ordonnés et désordonnés augmente rapidement, mais le
comportement dans le régime intermédiaire entre les deux extrèmes
-- ordre parfait et désordre complet -- est mal compris. Les
systèmes quasi-ordonnés brisent la symétrie de rotation ou de
translation et présentent des formes nouvelles et
non-conventionnelles de transport de la lumière. Les milieux
aléatoires qui diffusent anisotropiquement et les cristaux
liquides nématiques, les formes spéciales de cristaux photoniques
et les quasi-cristaux photoniques de Fibonacci sont des exemples
de systèmes quasi-ordonnés que nous étudions dans cette thèse.
Que se passe-t-il si une direction préférentielle de diffusion ou
un axe préférentiel de polarisabilité est présent dans un milieu
aléatoire ?
Comment la propagation de la lumière est elle modifiée dans une
structure périodique si un potential optique est superposé à la
structure cristalline ?
Dans cette thèse nous essayerons de répondre à ces questions, avec
des arguments théoriques, des simulations numériques et des
résultats expérimentaux.
Chvátal, Miloš. « Transportní a šumové charakteristiky tranzistorů MOSFET ». Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-233635.
Safieddine, Adham. « L'imagerie systématique de transcrits et de polysomes uniques révèle un mécanisme de transport dépendant de la protéine naissante ». Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTT025.
Local translation allows a spatial control of gene expression. Here, I participated in two mRNA localization screens imaging more than 1000 transcripts in total: (i) the first was a dual mRNA/protein screen that used a BAComics approach to co-detect mRNAs and the protein they encode; (ii) the second was done using a new high-throughput smFISH approach to screen all genes that encode centrosomal proteins and mitotic regulators. The first screen revealed cases of local translation at various subcellular compartments including cytoplasmic protrusions, centrosomes, Golgi, endosomes and the nuclear pore, which was never described before. Remarkably, translation of the nascent peptide was required for the transport of many localized transcripts. In addition, I showed that several mRNAs (such as ASPM and DYNC1H1) are translated in dedicated structures called translation factories.The second screen revealed 8 transcripts that are localized and translated at the centrosome. I showed that the localization of these 8 transcripts is regulated by the cell cycle, and that it also requires translation of the nascent polypeptide. Using the endogenous ASPM gene as a model, I imaged single mRNAs and polysomes with the MS2 and SunTag systems, respectively. This revealed a directed transport of ASPM polysomes towards centrosomes at the onset of mitosis, when this mRNA starts localizing. These data provide definitive evidence for a co-translational targeting mechanism dependent on motors as well as the nascent protein. This argues against the current dogma that mRNA transport is an RNA-based process acting on translationally repressed molecules. Instead, it suggests that SRP-like mechanisms are more widespread than previously thought
Teichert, Fabian, Andreas Zienert, Jörg Schuster et Michael Schreiber. « Electronic transport through defective semiconducting carbon nanotubes ». IOP Publishing Ltd, 2018. https://monarch.qucosa.de/id/qucosa%3A32462.
Adroguer, Pierre. « Propriétés de transport électronique des isolants topologiques ». Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2013. http://tel.archives-ouvertes.fr/tel-00832048.
Unge, Mikael. « Molecular Electronics : A Theoretical Study of Electronic Structure of Bulk and Interfaces ». Doctoral thesis, Linköpings universitet, Beräkningsfysik, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-6938.
Jabakhanji, Bilal. « Etudes des propriétés de transport de mono et de multicouches de graphène épitaxiées sur sic ». Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20130/document.
In this work, we present the characterization, mainly in transport, of epitaxial graphene layers produced by controlled sublimation of silicon carbide substrate (SiC). Electronic transport measurements are performed at low temperature (T ~ 1.6 K) and high magnetic field. In the first part, we explain the specific method ('graphite cap') used for growth of the samples studied in this work at CNM, Barcelona. The method of 'graphite cap' provides graphene ribbons homogeneous and isolated for the fabrication of electronic devices.Graphene on SiC gives very different results depending on the conditions of growth (temperature, pressure…) and the face of SiC substrate used: carbon face (C-face) or silicon face (Si-face).On the carbon face, two SiC polytypes have been used for the graphene growth:(i) On axis 6H-SiC: graphene ribbons are obtained on the whole surface. The length of ribbon approaches 600 µm and the width do not exceed 6 µm. The graphene follows the formation of steps on the SiC resulting from surface reconstruction during growth (‘step bunching'), which affects the graphene width. Monolayers were identified by Raman spectroscopy. For all measured samples, we found that the graphene is p-typed doped with a Hall concentration between 5x1012 and 5x1013cm-2. The quantum Hall effect is not observed because of the high doping level. But the Shubnikov de Haas oscillations (SdH) have been well resolved and studied. The phase of the oscillations is equal to zero, which is a signature from the presence of graphene monolayer.(ii) 8° off axis 4H-SiC: graphene ribbons obtained are larger and can reach a length of 600 µm and a width of 50 µm. The use of a SiC substrate with intentional disorientation upon cleavage of the initial surface allows the coalescence of the graphene ribbons. For all measured devices on this sample, we found that the graphene is p-typed doped (as determined from the sign of the Hall effect) with a Hall concentration between 8x1011 and 1013 cm-2. Mobilities varied between 1000 and 11000 cm²/Vs from device to device at 4K. Magnetoresistance revealed both Shubnikov-de Haas (SdH) oscillations, and interference phenomena (weak localization and antilocalization). For some low doped devices, Quantum Hall effect was observed. All quantum phenomena observed are signatures on the intrinsic properties of graphene monolayers.The main drawback of the epitaxial growth technique is the difficulty to control of the carrier density. Here, we investigate a bottom gate of a graphene device, epitaxially grown on the C-face of SiC substrate. The gate was realized by Nitrogen atoms implantation in the SiC crystal. The transport measurements have shown the effectiveness of the gate to control the type of carriers. The quantum Hall effect was observed for both types of carriers with remarkable Hall plateaus width (23 T).On the silicon face, we discuss results obtained from few layer graphene (FLG) grown epitaxially on the (0001) surface of a 6H-SiC substrate. Carriers are now like electrons through the buffer layer that exists on the Si face. The resulting FLG uniformly covers the substrate on which large step bunched terraces are also visible. The FLG is thicker at the step edges, as evidenced by micro-Raman analysis. Indeed, a noticeable anisotropy of the resistance has been detected by magnetotransport measurements at low temperature and high magnetic field. We will argue that this anisotropy originates from different mobilities, in the terraces and at the step edges
Twyffels, Laure. « Nucleo-cytoplasmic transport of TIS11 proteins and stress granule assembly : two potential new roles for Transportins ». Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209423.
Many RNA-binding proteins (RBPs) shuttle between the nucleus and the cytoplasm, where they can often fulfill different functions. RBPs also frequently localize into specialized microdomains that are not delimited by a membrane but in which specific factors are concentrated. Those include processing bodies and stress granules, which are cytoplasmic foci associated with mRNA decay, storage and translational repression. Post-transcriptional regulations mediated by RBPs can therefore be modulated rapidly and efficiently through changes in the localization of RBPs.
The first part of this work focuses on the subcellular localization and nucleo-cytoplasmic transport of the Drosophila RBP dTIS11. Like its mammalian and yeast homologues, dTIS11 binds AU-rich elements in the 3’UTR of its target mRNAs, and stimulates their rapid deadenylation and decay. Here, we have observed that although dTIS11 appears to be located mostly in the cytoplasm, it is constantly shuttling in and out of the nucleus. We show that the export of dTIS11 from the nucleus depends on the CRM1 exportin and is mediated by a hydrophobic NES that encompasses residues 101 to 113 in dTIS11 sequence. We also identify a cryptic Transportin-dependent PY nuclear localization signal (PY-NLS) in the tandem zinc finger region of dTIS11 and show that it is conserved across the TIS11 protein family. This PY-NLS partially overlaps the second zinc finger (ZnF2) of dTIS11. Importantly, mutations disrupting the capacity of the ZnF2 to coordinate a Zn2+ ion unmask dTIS11 and TTP PY-NLS and promote nuclear import. Taken together, our results indicate that the nuclear export of Drosophila and mammalian TIS11 proteins is mediated by CRM1 through diverging NESs, while their nuclear import mechanism might rely on a conserved PY-NLS whose activity is negatively regulated by ZnF2 folding.
In the second part, we present preliminary results which implicate the nucleo-cytoplasmic transport machinery in the assembly of stress granules (SGs) in mammalian cells. SGs contain silenced mRNPs which resemble stalled initiation complexes, and they form transiently in response to acute stress, concomitantly with a global arrest of translation. While their exact role remains undefined, it seems clear that SGs are able to exchange mRNPs with polysomes and with PBs, and that they are connected to post-transcriptional and translational regulations of gene expression during stress. Here, we show that inhibition of Transportin-1 expression or function does not affect the translational status of cells but impairs the assembly of stress granules. Finally, we show that Transportin-1 and -2B, but not -2A, localize into stress granules in response to several stresses.
In conclusion, we suggest two potential new roles for Transportins, in the nucleo-cytoplasmic traffic of TIS11 proteins on the one hand and in the assembly of stress granules on the other hand.
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Le compartimentage nucléo-cytoplasmique permet aux cellules eucaryotes de réguler l’expression génétique par des mécanismes post-transcriptionnels élaborés. Les ARN messagers subissent plusieurs étapes de maturation dans le noyau avant d’être exportés vers le cytoplasme où ils sont traduits et dégradés. Ces processus sont effectués via des protéines de liaison à l’ARN, ou RBPs. Beaucoup de RBPs exercent des fonctions différentes dans le noyau et dans le cytoplasme, et leur activité peut dès lors être rapidement modulée par une modification de leur localisation.
Le transport nucléo-cytoplasmique actif des protéines s’effectue à travers les pores nucléaires et fait majoritairement appel à des transporteurs solubles de la famille des karyophérines. Ceux-ci reconnaissent au sein des protéines à transporter une séquence-passeport appelée NLS (nuclear localization signal) ou NES (nuclear export signal) selon la direction nécessitée.
Le présent travail comporte deux parties. La première porte sur la localisation subcellulaire et le transport nucléo-cytoplasmique des protéines de la famille TIS11, et plus particulièrement de dTIS11 qui est le seul représentant de cette famille chez la Drosophile. Comme ses homologues dans d’autres espèces, dTIS11 est une RBP qui favorise la déadénylation et la dégradation de ses ARN messagers cibles. Nos résultats démontrent que dTIS11 fait la navette entre le noyau et le cytoplasme. L’export de dTIS11 hors du noyau est réalisé par la karyophérine CRM1 et fait appel à un NES différent de celui présent chez les protéines TIS11 mammaliennes. Nous identifions également un NLS cryptique au sein du domaine à deux doigts de zinc avec lequel dTIS11 lie l’ARN. Ce NLS correspond partiellement au signal consensus reconnu par la Transportine. Il est démasqué par la mutation du second doigt de zinc ;dans ces conditions, il permet l’import de dTIS11 par la Transportine. Enfin, nous montrons qu’il est conservé dans d’autres protéines de la famille TIS11.
Dans la seconde partie, nous nous intéressons aux granules de stress, qui sont des microdomaines cytoplasmiques dans lesquels se concentrent des RBPs et des ARN messagers non traduits en réponse à un stress cellulaire. Nous montrons que les karyophérines appartenant à la sous-famille des Transportines sont présentes dans ces granules et que l’inhibition de l’expression ou de la fonction des Transportines réduit la formation de ces granules en réponse à divers stress cellulaires. Nous écartons la possibilité que ce résultat soit un effet indirect d’un ralentissement du métabolisme traductionnel. Nos résultats suggèrent donc une implication des Transportines dans la formation des granules de stress.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished