Dissertations / Theses on the topic 'Fluctuation theorem'
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Carberry, David Michael, and dave_carberry@yahoo com au. "Optical Tweezers: Experimental Demonstrations of the Fluctuation Theorem." The Australian National University. Research School of Chemistry, 2006. http://thesis.anu.edu.au./public/adt-ANU20060410.122727.
Full textCarberry, David Michael. "Optical tweezers : experimental demonstrations of the fluctuation theorem /." View thesis entry in Australian Digital Theses Program, 2005. http://thesis.anu.edu.au/public/adt-ANU20060410.122727/index.html.
Full textBulnes, Cuetara Gregory. "Fluctuation theorem for quantum electron transport in mesoscopic circuits." Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209435.
Full textNous considérons deux modèles particuliers de circuits à deux canaux, chacun comportant deux électrodes. Le premier modèle étudié est constitué de deux plots quantiques en couplage capacitif, et chacun échangeant des électrons avec deux électrodes. Le deuxième modèle est quant à lui constitué d'un double plot quantique connecté à deux électrodes et modulant le courant dans un point quantique formé lui-même par la jonction de deux électrodes. Pour ces deux modèles, chaque canal est soumis à une différence de potentiel, ou force thermodynamique, générant des courants stationnaires fluctuants.
La statistique des courants pour ces deux modèles est obtenue en utilisant une équation maîtresse pour les probabilités d'occupation dans les plots quantiques et le nombre d'électrons transférés entre ceux-ci et les électrodes. Nous vérifions que la distribution de probabilité jointes des courants dans chaque canal ainsi obtenue vérifie un théorème de fluctuation dans la limite des temps long faisant intervenir les forces thermodynamique des deux canaux.
La question de l'émergence d'un théorème de fluctuation effectif pour la distribution de probabilité marginale du courant dans un des deux canaux est également investiguée. Nous montrons que dans la limite ou le rapport des courants est grande, un tel théorème de fluctuation effectif est satisfait individuellement pour le canal de plus faible courant comme observé expérimentalement. Ce théorème fait intervenir une affinité effective dépendante des forces thermodynamiques des deux canaux et des spécificités du modèle considéré. Son étude détaillée est faite pour les deux modèles mentionnés.
Par ailleurs, nous posons également la question de l'existence d'un théorème de fluctuation pour des temps de mesure finis. Nous montrons qu'en présence d'un théorème de fluctuation dans la limite de temps longs, un critère peut être énoncé sur la condition initiale des plots quantiques menant à un théorème de fluctuations à temps fini. Ce critère est également étendu au cas des théorèmes de fluctuations effectifs.
Finalement, nous faisons une étude thermodynamique du modèle composé d'un double plot quantique en présence de différences de potentiel électrique et de température entre les électrodes du circuit.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
Siemer, Bernd, Viktor Holubec, Petr Chvosta, and Philipp Maass. "Fluctuation dissipation theorem and Onsager coefficients in driven diffusion systems." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-198659.
Full textSiemer, Bernd, Viktor Holubec, Petr Chvosta, and Philipp Maass. "Fluctuation dissipation theorem and Onsager coefficients in driven diffusion systems." Diffusion fundamentals 24 (2015) 47, S. 1, 2015. https://ul.qucosa.de/id/qucosa%3A14567.
Full textGundermann, Julia. "The Crooks Fluctuation Theorem Derived for Two-Dimensional Fluid Flow and its Potential to Improve Predictions." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-156748.
Full textGundermann, Julia. "The Crooks Fluctuation Theorem Derived for Two-Dimensional Fluid Flow and its Potential to Improve Predictions." Doctoral thesis, Technische Universität Dresden, 2014. https://tud.qucosa.de/id/qucosa%3A28433.
Full textWong, Chun-Shang. "Statistical physics principles tested using dusty plasma and aerosol experiments." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6523.
Full textGraf, Daniel [Verfasser], and Christian [Akademischer Betreuer] Ochsenfeld. "Development of efficient electronic-structure methods based on the adiabatic-connection fluctuation-dissipation theorem and Møller–Plesset perturbation theory / Daniel Graf ; Betreuer: Christian Ochsenfeld." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2021. http://d-nb.info/123217629X/34.
Full textWatanabe, Kota. "Non-adiabatic effects in quantum geometric pumping." Kyoto University, 2017. http://hdl.handle.net/2433/225998.
Full textClark, Matthew Taylor. "The driven and stochastic dynamics of micro and nanoscale cantilevers in viscous fluid and near a solid boundary." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/29411.
Full textPh. D.
Brossault, Marc-Antoine. "Suivi temporel de la dynamique des structures : apports du théorème fluctuation-dissipation et de la dynamique lente pour l'évaluation de l'intégrité des structures de génie civil." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAU031/document.
Full textDuring strong seismic loadings, a structure may be damaged. This results in the appearing of cracks and then a reduction of the elastic properties of the structure. The degradation remains only transitory in the case of smaller seismic events. It consists in a sharp disruption of both the frequency and damping followed by their slow recovery to their initial values. This non linear phenomenon is called Slow Dynamics. It is explained by the gradual closing of the cracks which were initially present in the material and which were opened during the loading. We observed in the laboratory that the analysis of the Slow Dynamics in a beam before and after it is damaged allows to detect the increase of the crack density. The different sensitivties of the modes regarding a local damaging indicates a track to develop a method to locate the damages. The study of the Slow Dynamics in civil engineering structures demonstrated the possibility to detect the damaging also in this kind of system. The continuous monitoring of the damping highlighted a linear relationship between damping and the intensity of the ambiante vibration in the case of both the beams and real case structures. We explain this relation by applying the Fluctuation-Dissipation to these systems. Laboratory results and the proximity of the expression of the linear relationship wit hthe equations used in the theory of the Slow Dynamics suggest a dependency of this phenonmenon on the density of heterogeneities in the structure. Further research is however required in order to fully explain our observations and thus, to use them to monitor the state of health of structures
Gomez-Solano, Juan Rubén. "Nonequilibrium fluctuations of a Brownian particle." Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2011. http://tel.archives-ouvertes.fr/tel-00680302.
Full textPedurand, Richard. "Instrumentation for Thermal Noise Spectroscopy." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1356.
Full textThe resolution limit of gravitational wave interferometers is set by their mirrors' Brownian motion – or thermal noise - in the central part of their detection band, from 10Hz to 1kHz. This thermal noise frequency distribution is given by the mechanical energy dissipation mechanisms it originates from, in agreement with the fluctuation-dissipation theorem. This dissipation mainly derives from the optical coatings deposited on the mirrors to give them their reflectivity. To reduce this thermal noise, a new generation of gravitational wave detectors employing mirrors cooled to cryogenic temperature has been suggested. The development of new optical thin-film materials with low mechanical dissipation, operating at both room and cryogenic temperatures, therefore requires new experimental tools. The main object of this thesis is the construction of a new instrument, the CryoQPDI, which is an association between a high-resolution interferometer and a cryostat based on a pulse tube cooler. It can directly measure the Brownian motion of a microcantilever between 300 K and 7 K. By combining measurements made on a microcantilever before and after the deposition of a thin film, it is possible to characterize the internal mechanical dissipation of this thin film. This instrument will eventually contribute to the optimisation of optical coatings of future gravitational wave detectors, aiming at minimizing the limitations due to thermal noise
LEGGIO, Bruno. "Quantum fluctuations and correlations in equilibrium and nonequilibrium thermodynamics." Doctoral thesis, Università degli Studi di Palermo, 2014. http://hdl.handle.net/10447/90914.
Full textItami, Masato. "Non-equilibrium Statistical Theory for Singular Fluid Stresses." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215285.
Full textRobbins, Brian Alan. "The Correlated Dynamics of Micron-Scale Cantilevers in a Viscous Fluid." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/51090.
Full textPh. D.
Gundermann, Julia [Verfasser], Holger [Akademischer Betreuer] Kantz, and Günter [Akademischer Betreuer] Radons. "The Crooks Fluctuation Theorem Derived for Two-Dimensional Fluid Flow and its Potential to Improve Predictions / Julia Gundermann. Gutachter: Holger Kantz ; Günter Radons. Betreuer: Holger Kantz." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://d-nb.info/1069091766/34.
Full textBeuerle, Matthias [Verfasser], and Christian [Akademischer Betreuer] Ochsenfeld. "Development of low-scaling methods to calculate ground state energies and analytical gradients based on the adiabatic-connection fluctuation-dissipation theorem / Matthias Beuerle ; Betreuer: Christian Ochsenfeld." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2019. http://d-nb.info/1190563657/34.
Full textGundermann, Julia [Verfasser], Holger Akademischer Betreuer] Kantz, and Günter [Akademischer Betreuer] [Radons. "The Crooks Fluctuation Theorem Derived for Two-Dimensional Fluid Flow and its Potential to Improve Predictions / Julia Gundermann. Gutachter: Holger Kantz ; Günter Radons. Betreuer: Holger Kantz." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-156748.
Full textCaussarieu, Aude. "Propriétés dynamiques de la transition de Fréedericksz et vieillissement au point critique." Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2012. http://tel.archives-ouvertes.fr/tel-00790177.
Full textBoedecker, Geesche. "Resonance Fluorescence in a Photonic Crystal." Phd thesis, Universität Potsdam, 2013. http://opus.kobv.de/ubp/volltexte/2014/6959/.
Full textDie Arbeit befasst sich mit der Emission eines 2-Niveau-Atoms in einem photonischen Kristall mit einem treibenden Laser. Der photonische Kristall stellt für das Atom eine Umgebung dar, die seinen Zerfall verändert, insbesondere wenn die Übergangsfrequenz des Atoms nahe an der Bandkante ist. Es werden sowohl die Besetzungen als auch das Emissionsspektrum untersucht. Die Dynamik wird im Kontext offener Quantensysteme analysiert. Durch die vielfachen Reflexionen im photonischen Kristall hat das System ein endliches Gedächtnis, das die Markov-Näherung verhindert. Im Heisenberg-Bild stellen die Bewegungsgleichungen für die Systemvariablen eineunendliche Hierachie von Integro-Differentialgleichungen dar. Um ein geschlossenes System zu erhalten, sind Näherungen wie eine schwache Kopplung nötig. Zunächst wird ein einfacher photonischer Kristall betrachtet.: Der eindimensionale photonische Kristall, der aus wechselnden Lagen besteht. Die Blochmoden innerhalb und die Vakuummoden außerhalb des endlichen photonischen Kristalls sind durch eine Transformationsmatrix, die als Transfermatrix interpretiert werden kann, miteinander verbunden. Einfache Formeln für die Bandstruktur, Reflexion eines halb-unendlichen Kristalls, die lokale Zustandsdichte im absorbierenden Kristall werden gefunden; außerdem werden Defektmoden und negative Brechung diskutiert. Im quantenoptischen Teil der Arbeit werden zu Anfang drei Probleme diskutiert, die im Zusammenhang zum Problem der Resonanzfluoreszenz stehen und die analytisch berechnet werden können: Ein Dephasierungsmodell, das getriebenen Atom und Resonanzfluoreszenz im freien Raum. In der niedrigsten Ordnung der System-Bad-Kopplung werden die Erwartungswerte analytisch berechnet und die stationären Zustände werden für bestimmte Fälle diskutiert. Bei der Berechnung der Zweizeitkorrelationsfunktion und der Spektren taucht das zusätzliche Problem der Korrelationen zwischen den beiden Zeiten auf. Im Markov-Fall gilt das Quantenregressionstheorem. Im allgemeinen Fall kann stattdessen das Fluktuations-Dissipations-Theorem benutzt werden. Die Korrelationsfunktionen werden mit zwei verschiedenen Methoden berechnet. Innerhalb der gewählten Näherungen liefern beide Methoden dasselbe Resultat. Einige Plots zeigen die Abhängigkeit des Spektrums von den verschiedenen Parametern. Mehrere Beispiele für Squeezing-Spektren werden mit den verschiedenen Näherungen gezeigt. Eine Projektions-Operator-Methode wird benutzt, um zwei Arten einer Markov-Entwicklung zu implementieren, mit und ohne Faltungsintegral. Die niedrigste Ordnung ist identisch mit der niedrigsten Ordnung der System-Bad-Kopplung, wohingegen höhere Ordnungen andere Resultate ergeben.
Bérut, Antoine. "Fluctuations and Interactions of Brownian particles in multiple Optical Traps." Thesis, Lyon, École normale supérieure, 2015. http://www.theses.fr/2015ENSL1003/document.
Full textWe experimentally study the fluctuations of Brownian micro-particles trapped with optical tweezers arranged in various spatial configurations. We give a general description of the set-up and detail four different experiments we conducted. We first use a single particle in a double-well potential to model a two-state memory system. We verify the Landauer principle on the minimal energetic cost to erase one bit of information, and we use a detailed version of a fluctuation theorem to retrieve the expected energetic bound. We then use two particles in two different traps to study the hydrodynamic interactions between two systems kept at different effective temperatures. Contrary to what was previously observed, we show that the sol-gel transition of gelatine does not provide any anomalous fluctuations for the trapped particle when the sample is quenched below gelification temperature. However, we show that an effective temperature is created when a well chosen random noise is added on one trap position. We demonstrate that the random forcing on one particle induces an instantaneous correlation between the two particles motions, and an energy exchange from the virtually hot particle to the cold one, which is in equilibrium with the thermal bath. We show a good agreement between the experimental data and the predictions from an hydrodynamic coupling model. Finally, we describe the use of micro-fluidic channels to create a shear flow at the micron size, and we discuss the possibility to interpret the force due to the shear-flow in terms of an effective temperature by testing a fluctuation-dissipation relation
Ghosh, Santunu. "Study on the origin of 1/f in bulk acoustic wave resonators." Thesis, Besançon, 2014. http://www.theses.fr/2014BESA2046/document.
Full textSince a few decades, frequency control technology has been at the heart of modern day electronics due to its huge areaof applications in communication systems, computers, navigation systems or military defense. Frequency controldevices provide high frequency stabilities and spectral purities in the short term domain. However, improvement of theperformance of these devices, in terms of frequency stability, remains a big challenge for researchers. Reducing noise inorder to increase the short term stability and avoid unwanted switching between channels is thus very desirable. It iscommonly admitted that the fundamental limitation to this short-term stability is due to flicker frequency noise in theresonators. In this manuscript, a first chapter recalls some basic facts about acoustic, crystallography and definitions oftime and frequency domain needed to explore ultra-stable resonators and oscillators. The second chapter is devoted to asummary of the literature on flicker frequency noise. Then, the third chapter concerns our studies on Handel’s quantum1/f noise model, which although criticized by many, is still the only one that provides an estimation of the flooramplitude of 1/f noise that is not invalidated by experimental data. In the fourth chapter, another approach, based on thefluctuation-dissipation theorem, is used in order to put numerical constraints on a model of 1/f noise caused by aninternal (or structural) dissipation proportional to the amplitude and not to the speed. The last chapter is devoted toexperimental results. An ultra-stable resonator used during this study is described. Phase noise measurements on severalbatches of resonators are given. Measurements of resonator parameters have been done at low temperature in order tocorrelate them with noise results. Another approach with a procedure that use transient pseudo periodic oscillations andput to their limits the capacities of presently available digital oscilloscopes, is presented, in order to assess rapidly thequality of various resonators. Finally, conclusions and perspectives are given
Zeileis, Achim. "A unified approach to structural change tests based on F statistics, OLS residuals, and ML scores." Institut für Statistik und Mathematik, WU Vienna University of Economics and Business, 2005. http://epub.wu.ac.at/714/1/document.pdf.
Full textSeries: Research Report Series / Department of Statistics and Mathematics
Zimmermann, Robert. "How large spheres spin and move in turbulent flows." Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2012. http://tel.archives-ouvertes.fr/tel-00737746.
Full textPloetz, Elizabeth Anne. "Fluctuation solution theory." Diss., Kansas State University, 2014. http://hdl.handle.net/2097/18390.
Full textDepartment of Chemistry
Paul E. Smith
The Kirkwood-Buff (KB) theory of solutions, published in 1951, established a route from integrals over radial (pair) distribution functions (RDFs) in the grand canonical ensemble to a set of thermodynamic quantities in an equivalent closed ensemble. These “KB integrals” (KBIs) can also be expressed in terms of the particle-particle (i.e., concentration or density) fluctuations within grand canonical ensemble regions. Contributions by Ben-Naim in 1977 provided the means to obtain the KBIs if one already knew the set of thermodynamic quantities for the mixture of interest; that is, he provided the inversion procedure. Thus, KB theory provides a two-way bridge between local (microscopic) and global (bulk/thermodynamic) properties. Due to its lack of approximations, its wide ranging applicability, and the absence of a competitive theory for rigorously understanding liquid mixtures, it has been used to understand solution microheterogeneity, solute solubility, cosolvent effects on biomolecules, preferential solvation, etc. Here, after using KB theory to test the accuracy of pair potentials, we present and illustrate two extensions of the theory, resulting in a general Fluctuation Solution Theory (FST). First, we generalize KB theory to include two-way relationships between the grand canonical ensemble’s particle-energy and energy-energy fluctuations and additional thermodynamic quantities. This extension allows for non-isothermal conditions to be considered, unlike traditional KB theory. We illustrate these new relationships using analyses of experimental data and molecular dynamics (MD) simulations for pure liquids and binary mixtures. Furthermore, we use it to obtain conformation-specific infinitely dilute partial molar volumes and compressibilities for proteins (other properties will follow) from MD simulations and compare the method to a non-FST method for obtaining the same properties. The second extension of KB theory involves moving beyond doublet particle fluctuations to additionally consider triplet and quadruplet particle fluctuations, which are related to derivatives of the thermodynamic properties involved in regular KB theory. We present these higher order fluctuations obtained from experiment and simulation for pure liquids and binary mixtures. Using the newfound experimental third and fourth cumulants of the distribution of particles in solution, which can be extracted from bulk thermodynamic data using this extension, we also probe particle distributions’ non-Gaussian nature.
Mahajan, Salil. "CCM3 as applied to an idealized all land zonally symmetric planet, Terra Blanda 3." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1422.
Full textFriedrich, Benjamin M. "Nonlinear dynamics and fluctuations in biological systems." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-234307.
Full textDas Thema der vorliegenden Habilitationsschrift in Theoretischer Biologischer Physik ist die nichtlineare Dynamik funktionaler biologischer Systeme und deren Robustheit gegenüber Fluktuationen und äußeren Störungen. Wir entwickeln hierzu theoretische Beschreibungen für zwei grundlegende biologische Prozesse: (i) die zell-autonome Kontrolle aktiver Bewegung, sowie (ii) selbstorganisierte Musterbildung in Zellen und Organismen. In Kapitel 2, untersuchen wir Bewegungskontrolle auf zellulärer Ebene am Modelsystem von Zilien und Geißeln. Spontane Biegewellen dieser dünnen Zellfortsätze ermöglichen es eukaryotischen Zellen, in einer Flüssigkeit zu schwimmen. Wir beschreiben einen neuen physikalischen Mechanismus für die Synchronisation zweier schlagender Geißeln, unabhängig von direkten hydrodynamischen Wechselwirkungen. Der Vergleich mit experimentellen Daten, zur Verfügung gestellt von unseren experimentellen Kooperationspartnern im Labor von J. Howard (Yale, New Haven), bestätigt diesen neuen Mechanismus im Modellorganismus der einzelligen Grünalge Chlamydomonas. Der Gegenspieler dieser Synchronisation durch mechanische Kopplung sind Fluktuationen. Wir bestimmen erstmals Nichtgleichgewichts-Fluktuationen des Geißel-Schlags direkt, wofür wir eine neue Analyse-Methode der Grenzzykel-Rekonstruktion entwickeln. Die von uns gemessenen Fluktuationen entstehen mutmaßlich durch die stochastische Dynamik molekularen Motoren im Innern der Geißeln, welche auch den Geißelschlag antreiben. Um die statistische Physik dieser Nichtgleichgewichts-Fluktuationen zu verstehen, entwickeln wir eine analytische Theorie der Fluktuationen in einem minimalen Modell kollektiver Motor-Dynamik. Zusätzlich zur Regulation des Geißelschlags durch mechanische Kräfte untersuchen wir dessen Regulation durch chemische Signale am Modell der Chemotaxis von Spermien-Zellen. Dabei charakterisieren wir einen grundlegenden Mechanismus für die Navigation in externen Konzentrationsgradienten. Dieser Mechanismus beruht auf dem aktiven Schwimmen entlang von Spiralbahnen, wodurch ein räumlicher Konzentrationsgradient in der Phase eines oszillierenden chemischen Signals kodiert wird. Dieser Chemotaxis-Mechanismus unterscheidet sich grundlegend vom bekannten Chemotaxis-Mechanismus von Bakterien. Wir entwickeln eine Theorie der senso-motorischen Steuerung des Geißelschlags während der Spermien-Chemotaxis. Vorhersagen dieser Theorie werden durch Experimente der Gruppe von U.B. Kaupp (CAESAR, Bonn) quantitativ bestätigt. In Kapitel 3, untersuchen wir selbstorganisierte Strukturbildung in zwei ausgewählten biologischen Systemen. Auf zellulärer Ebene schlagen wir einen einfachen physikalischen Mechanismus vor für die spontane Selbstorganisation von periodischen Zellskelett-Strukturen, wie sie sich z.B. in den Myofibrillen gestreifter Muskelzellen finden. Dieser Mechanismus zeigt exemplarisch auf, wie allein durch lokale Wechselwirkungen räumliche Ordnung auf größeren Längenskalen in einem Nichtgleichgewichtssystem entstehen kann. Auf der Ebene des Organismus stellen wir eine Erweiterung der Turingschen Theorie für selbstorganisierte Musterbildung vor. Wir beschreiben eine neue Klasse von Musterbildungssystemen, welche selbst-organisierte Muster erzeugt, die mit der Systemgröße skalieren. Dieser neue Mechanismus erfordert weder eine vorgegebene Kompartimentalisierung des Systems noch spezielle Randbedingungen. Insbesondere kann dieser Mechanismus proportionale Muster wiederherstellen, wenn Teile des Systems amputiert werden. Wir bestimmen analytisch die Hierarchie aller stationären Muster und analysieren deren Stabilität und Einzugsgebiete. Damit können wir zeigen, dass dieser Skalierungs-Mechanismus strukturell robust ist bezüglich Variationen von Parametern und sogar funktionalen Beziehungen zwischen dynamischen Variablen. Zusammen mit Kollaborationspartnern im Labor von J. Rink (MPI CBG, Dresden) diskutieren wir Anwendungen auf das Wachstum von Plattwürmern und deren Regeneration in Amputations-Experimenten
Urbani, Pierfrancesco. "Theory of fluctuations in disordered systems." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112019.
Full textIn this thesis we have studied many aspects of the physics of disordered and glassy systems. The first part of the work is about the theory of dynamical fluctuations in the beta regime. When a system undergoes a dynamical arrest, it can be studied by introducing an appropriate dynamical correlation function that plays the role of the order parameter of the transition. To understand the collective effects underlying the glass transition we have studied the fluctuations of the order parameter on a time scale where the system is relaxed in a typical metastable glassy state. To do this we have seen that coming from the glass phase the system develops critical fluctuations with a diverging correlation length at the mean field level. We have thus derived an effective field theory by focusing only on them. This field theory can be used firstly to derive the mode-coupling exponent parameter that controls the relaxation of the dynamical correlation function when the system relaxes in a metastable glassy state. Moreover we can give a Ginzburg Criterion that can be used to determine the region of validity of the Gaussian approximation. These considerations are valid in the beta regime. To clarify what happens in the alpha regime we have studied a quasi-equilibrium construction, called Boltzmann-Pseudodynamics, recently introduced in order to describe with static techniques the long time regime of glassy dynamics. We have extended this formalism to structural glasses by producing a new set of dynamical equations. We have done this in the simplest approximation scheme that is called Hypernetted Chain. Two results have been obtained : firstly, we have computed the mode-coupling exponent parameter and we have shown that it coincides with the one obtained with the formalism of the first part of the thesis ; secondly we have studied the aging regime and we have derived that the condition that determines the fluctuation-dissipation ratio is a marginal stability one. In the third part of the thesis we have studied the theory of amorphous states of hard spheres in high dimensions. Hard spheres provide simple models of glasses and they are extensively studied for the jamming transition. In our framework jammed states can be thought as infinite pressure limit of metastable glassy states. During the last years it has been derived a mean field theory of hard spheres based on the 1RSB assumption on the structure of the free energy landscape. However it has been realized that this construction is inconsistent for what concerns the property of the packings at jamming. In the present work we have firstly investigated the possibility of an instability of the 1RSB solution and we have actually found that the 1RSB solution is unstable in the jamming part of the phase diagram. At the same time we have been able to compute the mode-coupling exponent parameter for this system. In order to go beyond the 1RSB solution we have first tried a 2RSB ansatz and then a fullRSB solution. We have derived a set of variational equations that are very close to the ones that have been derived in the Sherrington-Kirkpatrick model. We have solved numerically the equations and we have shown that the fullRSB solution seems to predict that the plateau value of the mean square displacement scale as the pressure to a power close to 3/2 as it seems to be predicted by scaling arguments and in contrast with the 1RSB predictions that show a scaling with the inverse of the pressure. The last chapter of the thesis is on the mode-coupling theory when the glass transition is becoming continuous. We have been able to show that in such a situation a detailed characterization of the solution of the equations can be obtained in the long time regime
Marchal, Philippe. "Theorie des fluctuations, probabilites sur les arbres." Paris 6, 1999. http://www.theses.fr/1999PA066323.
Full textRousakis, Michail. "Essays on economic fluctuations." Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/55269/.
Full textMennuni, Alessandro. "Aggregate and disaggregated fluctuations." Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/192743/.
Full textHaselwandter, Christoph Andreas. "Multiscale theory of fluctuating interfaces." Thesis, Imperial College London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444163.
Full textGarrity, Patrick Louis. "Nanoscale Thermal Fluctuation Spectroscopy." ScholarWorks@UNO, 2009. http://scholarworks.uno.edu/td/912.
Full textHägg, Jonas. "Gaussian fluctuations in some determinantal processes." Doctoral thesis, KTH, Matematik (Inst.), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4343.
Full textQC 20100716
LEMARCHAND, FRAIKIN ANNE. "Fluctuations dans les systemes macroscopiques : theorie et experience." Paris 6, 1990. http://www.theses.fr/1990PA066508.
Full textKennedy, Thomas Albert Brian. "Theory of fluctuations and collisions in quantum optics." Thesis, Queen's University Belfast, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254184.
Full textPorter, Andrew Robert. "Quantum fluctuations and excitations within electronic-structure theory." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621983.
Full textAlemany, i. Arias Anna. "Dynamic force spectroscopy and folding kinetics in molecular systems." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/284197.
Full textLa codificació de la informació genètica, la regulació de l'expressió dels gens, el transport de nutrients dins la cèl·lula, la protecció immunològica contra agents infecciosos... Aquests són alguns dels processos moleculars que s'esdevenen en organismes vius i són crucials per la seva supervivència. Entendre el funcionament d'aquests fenòmens és vital per conèixer les lleis que governen l'escala microscòpica i per entendre, preveure, o fins i tot trobar cures de malalties amb origen molecular, com el Parkinson, l'Alzheimer, o alguns càncers. Els experiments amb una única molècula són una eina molt poderosa i versàtil que permet investigar molts processos moleculars a escala de molècula i trajectòria individual, amb una resolució espaio-temporal sense precedents. Una eina paradigmàtica per dur a terme aquest tipus d'estudis són les “pinces òptiques”, consistents en un feix de llum coherent focalitzat capaç d'atrapar partícules de plàstic microscòpiques utilitzant la conservació del moment. Aquest instrument permet manipular una única biomolècula amb precisió nanomètrica, i exercir-hi forces en el rang entre 0 i 100 pN. La diversitat de sistemes estudiats amb les pinces òptiques augmenta cada dia. En aquesta tesi, s'utilitzen per desxifrar els mecanismes del plegament i desplegament d'àcids nucleics i d'una proteïna quan s'hi aplica una força. A més, les propietats d'un únic enllaç entre un antigen i un anticòs s'investiguen de manera qualitativa, mesurant la correlació entre l'afinitat i l'elasticitat de la unió. Els resultats d'aquesta tesi obren la porta a la caracterització termodinàmica i cinètica de processos moleculars complexos que s'esdevenen en condicions d'equilibri parcial (com ocorre en organismes vius) utilitzant l'espectroscòpia dinàmica de forces (és a dir, l'estudi de les forces característiques per induir transicions moleculars) i els teoremes de fluctuació (que proporcionen estimacions de l'energia lliure mitjançant mesures irreversibles). Alguns exemples poden trobar-se en els estats cinètics i metaestables relacionats amb el plegament mecànic -com els estats intermedis i mal plegats-, en la interacció intermolecular, o en estats metaestables que es donen en reaccions de polimerització -com la translocació dels motors moleculars.
Acharya, Arjun R. "Free energy differences : representations, estimators, and sampling strategies." Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/602.
Full textBENHASSINE, BAHA. "Theorie semi-classique des fluctuations dans la matiere nucleaire." Nantes, 1994. http://www.theses.fr/1994NANT2030.
Full textAvanzini, Francesco. "Quantum molecular trajectory and stochastic theories of quantum fluctuations." Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3424724.
Full textLa teoria di Bohm è una formulazione della Meccanica Quantistica che caratterizza lo stato di un sistema quantistico attraverso sia la funzione d’onda, come la teoria standard, sia le coordinate (le posizioni) di tutte le particelle che evolvono nel tempo secondo traiettorie quantistiche continue. Inoltre, un ensemble statistico di tutte le possibile traiettorie, che deriva dall’impossibilità di conoscere la posizione iniziale di tutte le particelle, stabilisce l’esatta corrispondenza con la Meccanica Quantistica tradizionale. Da un punto di vista computazionale, la teoria di Bohm è stata impiegata in Chimica Fisica principalmente per sviluppare nuove strategie risolutive dell’equazione di Schrödinger o nuove approssimazioni semi-classiche della Meccanica Quantistica. Da un punto di vista teorico, la caratteristica più attraente della teoria di Bohm è quella di essere il contesto naturale per definire un mappa concettuale tra il formalismo quantistico e la nostra rappresentazione dei sistemi chimici. I sistemi chimici sono composti di molecole, ma l’idea stessa di molecola è associata ad una specifica posizione spaziale delle particelle, i.e., i nuclei degli atomi. La descrizione statistica della Meccanica Quantistica convenzionale, sulla base della sola funzione d’onda, è insufficiente per definire una chiara corrispondenza con questa immagine delle molecole. Infatti, i chimici fanno spesso affidamento alla Meccanica Classica per aggirare questa difficoltà della teoria quantistica standard. Tuttavia, se la posizione delle particelle è inclusa nel formalismo quantistico, così come fa la teoria di Bohm, la corrispondenza può essere definita in modo autoconsistente. In altre parole, la teoria di Bohm sembra essere il contesto formale idoneo per rappresentare quantisticamente le molecole e il loro moto. Comunque, la raffigurazione chimica dei sistemi molecolari corrisponde ad una singola traiettoria di Bohm dato che si assume implicitamente che i componenti delle molecole abbiano una specifica posizione spaziale indipendentemente dal fatto che essa sia nota o meno. Di conseguenza, si è sviluppata una metodologia quantistica che si basa sull’assunzione che una singola traiettoria di Bohm, cioè una traiettoria molecolare quantistica, descrive correttamente i sistemi molecolari e il moto molecolare. In primo luogo, viene esaminata la corrispondenza tra una singola traiettoria di Bohm e la Meccanica Quantistica convenzionale dato che si rinuncia all’ensemble di traiettorie. Si verifica che tale corrispondenza esiste attraverso un esperimento numerico e si dimostra formalmente che le proprietà statistiche di una singola traiettoria spiegano la descrizione probabilistica della Meccanica Quantistica. Una volta che la coerenza di questa metodologia è stata verificata, vengono esaminate accuratamente le sue previsioni. Per esempio, si prendono in considerazione le costanti del moto (come l’energia) associate all’evoluzione temporale delle particelle e il comportamento di semplici sistemi chimici, e.g., il moto vibrazionale di singole molecole che interagiscono con un campo esterno risonante. In questo modo, proprietà inaspettate del moto molecolare emergono naturalmente. In secondo luogo, si considera la sfida di descrivere sistemi a molti componenti (quali sono i sistemi chimici in condizioni ordinarie). È ben noto che il calcolo della traiettoria di Bohm e della funzione d’onda è molto costoso computazionalmente. Comunque, le proprietà statistiche della traiettoria di Bohm permettono di derivare teorie stocastiche per esaminare la dinamica di sistemi quantistici aperti, come qualche molecola (o qualche grado di libertà) interagente con l’ambiente (le altre molecole). Uno dei metodi stocastici sviluppati correla la dinamica della matrice densità ridotta, per i gradi di libertà di interesse, all’evoluzione delle corrispondenti coordinate di Bohm. In altre parole, l’equazione di Bohm, che determina la velocità delle particelle attraverso la funzione d’onda, è sostituita da un’equazione stocastica che approssima la velocità di un sott’insieme di coordinate attraverso la matrice densità ridotta. In questo modo, le fluttuazioni quantistiche indotte dall’ambiente sono prese in considerazione. Il vantaggio del metodo riguarda la sua capacità di descrivere i sistemi quantistici, compresi quelli aperti, in termini di una traiettoria quantistica. Questo potrebbe permettere la comprensione del moto molecolare durante un esperimento spettroscopico. Di particolare interesse è la possibilità di esaminare sistemi reattivi, come quelli in cui avvengono cambi conformazionali. Come è ben noto, le reazioni chimiche possono essere totalmente caratterizzate solo attraverso il moto delle particelle e in questa tesi viene definita esattamente una metodologia quantistica che fornisce una descrizione autoconsistente del moto molecolare.
Burren, Daniel. "Essays on economic fluctuations." Berlin dissertation.de, 2009. http://d-nb.info/994502990/04.
Full textBridgman, Helen Amanda. "Classical and quantum fluctuations in superstring cosmology." Thesis, University of Portsmouth, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247490.
Full textWesterhoff, Frank. "Chartists, fundamentalists, and exchange rate fluctuations /." Aachen : Shaker, 2002. http://www.gbv.de/dms/zbw/355764563.pdf.
Full textChotibut, Thiparat. "Statistical Fluctuations in Evolutionary and Population Dynamics." Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493257.
Full textPhysics
Karahasanovic, Una. "Fluctuation-driven phase reconstruction at itinerant ferromagnetic quantum critical points." Thesis, University of St Andrews, 2012. http://hdl.handle.net/10023/3188.
Full textElston, Timothy G. "The effects on intrinsic fluctuations of chaotic dynamics." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/29440.
Full textHahn, Aljoscha M. [Verfasser], and Andreas [Akademischer Betreuer] Engel. "On free energy calculations using fluctuation theorems of work / Aljoscha M. Hahn. Betreuer: Andreas Engel." Oldenburg : IBIT - Universitätsbibliothek, 2011. http://d-nb.info/1016981139/34.
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