Global ETD Search

141	Contrôle de l'état interne d'un atome unique piégé et expériences d'interférences à deux photons : vers l'information quantique avec des atomes neutres Beugnon, Jérôme 25 September 2007 (has links) (PDF) Les atomes neutres sont de bons candidats pour la réalisation de protocoles d'information quantique. Cette thèse présente des expériences effectuées dans cette perspective sur des atomes individuels de rubidium piégés dans des pinces optiques de taille microscopique. Ces pinces sont obtenues en focalisant un faisceau laser sur une taille inférieure à un micromètre. Nous montrons que l'on peut contrôler l'état de chaque atome individuellement en faisant des transitions Raman à deux photons entre deux niveaux hyperfins de l'état fondamental. Nous observons des oscillations de Rabi entre ces deux niveaux à des fréquences pouvant atteindre plusieurs mégaHertz. Nous étudions aussi la cohérence de ce système par des expériences de franges de Ramsey et d'écho de spin. Des temps de cohérence de plusieurs dizaines de millisecondes sont mesurés. De plus, dans le but de manipuler des atomes dans un registre quantique, nous démontrons le déplacement d'une pince optique contenant un atome et le transfert de celui-ci d'une pince dans une autre sans perte de cohérence ni chauffage. Finalement, en vue de réaliser l'intrication conditionnelle de deux atomes, nous étudions l'émission de photons par ces atomes piégés. Nous montrons que ces atomes sont des sources de photons uniques déclenchables efficaces et nous décrivons l'observation d'interférences à deux photons entre deux photons uniques émis par deux atomes voisins indépendants. Ces interférences quantiques prouvent l'indiscernabilité des photons émis par chaque atome. Information quantique Franges de Ramsey Manipulation d'atomes uniques Photons uniques Transitions Raman Interférences à deux photons Oscillation de Rabi Intrication conditionnelle
142	Optimal fiscal policy, limited commitment and learning Caprioli, Francesco 03 July 2009 (has links) Esta tesis trata sobre cómo la autoridad fiscal debe fijar los impuestos distorsivos de manera óptima. El capítulo 1 analiza el problema de la política fiscal cuando el gobierno tiene un incentivo a hacer default con su deuda externa. El capítulo 2 trata sobre el problema de la política fiscal cuando los agentes no conocen cómo el gobierno fija las tasas impositivas. La principal conclusión que obtengo es que, en ambos contextos, el resultado de suavidad de las tasas, que es estándar en la literatura de imposición óptima, se rompe. Cuando los gobiernos no tienen una tecnología de compromiso, los impuestos responden a los incentivos de default; cuando los agentes poseen información parcial sobre el modelo subyacente de la economía, los impuestos dependen de sus expectativas sobre los mismos. / This thesis is about how fiscal authority should optimally set dissorting taxes. Chapter 1 deals with the optimal fiscal policy problem when the government has an incentive to default on external debt. Chapter 2 deals with the optimal fiscal policy problem when households do not know how government sets taxes. The main conclusion I get is that, in each of these two contexts, the tax smoothing result, which is the standars result in the optimal taxation literature, is broken. When governments do not have a commitment technology taxes respond to the incentives to default; when agents have partial information about the underlying economic model, taxes depend on their beliefs about it. government debt impostos òptims limited commitment learning ramsey taxation deuda internacional deuda pública compromiso parcial impuestos óptimos aprendizaje deute internacional deute públic compromís parcial aprenentatge international debt 33 338
143	Continuous Beam of Laser-Cooled Ytterbium Atoms for Precision Measurements Rathod, Ketan D January 2014 (has links) (PDF) What if an elementary particle such as an electron had an intrinsic electric dipole moment (EDM)? Existence of such an EDM would be an indication of time-reversal symmetry violation in the laws of Physics. The Standard model of Physics is considered incomplete, and theories that go beyond the standard model predict existence of such EDM’s within experimental reach. Experiments that search for their existence serve as a test bed for these theories. Use of laser-cooled Yb atoms launched in a fountain for EDM search has been proposed earlier. This thesis describes the main experimental work on generating a continuous cold beam of Yb atoms using laser cooling. Such cold beams are ideal for performing EDM experiments and have several advantages over the more common pulsed fountain. We demonstrate two ways to achieve this (i) extracting the beam from atoms trapped in 2- dimensions and (ii) deflecting the atomic beam using 1D-optical molasses. We find that the latter method gives a longitudinal temperature of 41 mK, which is a factor of 3 better than the former one. We also demonstrate the implementation of Ramsey’s separated oscillatory field technique in a thermal beam to measure the larmor precession frequency with high precision. This serves as a first step towards implementation with cold beam. Extending the work reported here, we suggest future experiment for measuring an EDM. Symmetry Laser-Cooled Ytterbium Atoms Rubidium Atoms Thermal Beams Continuous Beams Ytterbium Atoms Ramsey Fringes Magneto Optical Trap (MOT) Atoms in Oscillating Fields Yb Laser Cooled Yb Atoms Rb Cold Rb Atom Physics
144	Determinacy in the Low Levels of the Projective Hierarchy Cotton, Michael R. 06 August 2012 (has links) No description available. Logic Mathematics determinacy descriptive set theory large cardinal measurable cardinal set theory projective Borel ZFC homogeneously Suslin ultrapower Ramsey cardinal analytic determinacy analytic Borel hierarchy projective hierarchy sets Borel determinacy
145	Essays on regulatory impact in electricity and internet markets Roderick, Thomas Edward 26 June 2014 (has links) This dissertation details regulation's impact in networked markets, notably in deregulated electricity and internet service markets. These markets represent basic infrastructure in the modern economy; their innate networked structures make for rich fields of economic research on regulatory impact. The first chapter models deregulated electricity industries with a focus on the Texas market. Optimal economic benchmarks are considered for markets with regulated delivery and interrelated network costs. Using a model of regulator, consumer, and firm interaction, I determine the efficiency of the current rate formalization compared to Ramsey-Boiteux prices and two-part tariffs. I find within Texas's market increases to generator surplus up to 55% of subsidies could be achieved under Ramsey-Boiteux pricing or two-part tariffs, respectively. The second chapter presents a framework to analyze dynamic processes and long-run outcomes in two-sided markets, specifically dynamic platform and firm investment incentives within the internet-service platform/content provision market. I use the Ericson-Pakes framework applied within a platform that chooses fees on either side of its two-sided market. This chapter determines the impact of network neutrality on platform investment incentives, specifically whether to improve the platform. I use a parameterized calibration from engineering reports and current ISP literature to determine welfare outcomes and industry behavior under network neutral and non-neutral regimes. My final chapter explores retail firm failure within the deregulated Texas retail electricity market. This chapter investigates determinants of retail electric firm failures using duration analysis frameworks. In particular, this chapter investigates the impact of these determinants on firms with extant experience versus unsophisticated entrants. Understanding these determinants is an important component in evaluating whether deregulation achieves the impetus of competitive electricity market restructuring. Knowing which economic events decrease a market's competitiveness helps regulators to effectively evaluate policy implementations. I find that experience does benefit a firm's duration, but generally that benefit assists firm duration in an adverse macroeconomic environment rather than in response to adverse market conditions such as higher wholesale prices or increased transmission congestion. Additionally, I find evidence that within the Texas market entering earlier results in a longer likelihood of duration. / text Industrial organization Regulation Regulatory economics Deregulation Electricity Network neutrality Net neutrality ISP Internet service provider Retail electricity markets Wholesale electricity markets Regulated delivery Regulated transmission ERCOT PUCT Zonal energy market Economics Energy markets Two-sided markets Platforms Platform markets Ericson-Pakes algorithms Pakes-McGuire algorithm Second-best regulation Ramsey-Boiteux pricing Ramsey pricing Boiteux pricing Electricity generation Electricity production Electricity consumption Dynamic investment Market entry Market exit Firm investment
146	UCN Detector development for the TRIUMF Neutron EDM experiment Fleurette, Doresty Fonseca 07 April 2016 (has links) A new measurement of the neutron electric dipole moment (nEDM) is being developed at TRIUMF, where a high density source of ultra cold neutrons (UCN) is currently under construction. A fast, high-efficiency UCN detector is needed for the experiment, and a 6-Li doped glass scintillation detector is being explored for this purpose. In this work, simulations and test measurements were carried out to optimize the light guide design for the new UCN detector. Acrylic and air-core light guides, the latter with two different reflecting surfaces, were considered. Three prototype light guides were constructed and tested, and results were compared with simulations. The best solution was found to be an acrylic guide, wrapped with mylar foil. For a guide 12 cm in length as required by the experimental layout, a lower limit of approximately 25 photoelectrons per neutron capture was established for the proposed geometry and photomultiplier configuration. / May 2016
147	The Laie Hawaii Temple: A History from Its Conception to Completion Dowse, Richard J. 12 July 2012 (has links) The Laie Hawaii Temple majestically overlooks the beaches of Oahu and has stood as an emblem of the Latter-day Saint faith to the world since 1919. Although the structure is iconic and highly significant to Latter-day Saints, a comprehensive history of the Laie Hawaii Temple has never been published. This thesis provides such a history from the conception of the temple until its dedication. The history of this particular temple is important for several reasons. At its dedication, the temple in Laie became the fifth operating temple of The Church of Jesus Christ of Latter-day Saints. It was the first dedicated temple outside of the state of Utah (following the exodus) and outside of North America. It was also the first temple built in one of the missions of the Church. It was a pioneering temple as one of the first that catered to a large number of patrons from different cultures speaking different languages. Its multi-cultural, multi-lingual integration is something that would not be seen in other temples for several decades. Over the years, the temple and the attractions built around it have drawn millions of other visitors as well. Its location has made it an internationally recognized edifice and a valuable tool for the Church to introduce its message to the world. This history is also compelling because of what the temple in Laie, Hawaii represents in terms of the Latter-day Saint conception of the doctrine of the "gathering." As the first temple built outside of the traditional centers of Mormon colonization, this temple became an early prototype of a method of gathering that does not appear to begin taking hold Church-wide until the mid-twentieth century. Ahead of its time in other ways, the temple was built in a place where, according to the thinking of the time, Church membership was not yet sizable enough to warrant a temple. This thesis explains why the temple was built in Hawaii. These aspects of the temple's history produced ramifications that continue to impact the Church today, nearly 100 years later. As with many temples, a folk history of oral tradition has developed around the story of the Laie Hawaii Temple. This thesis will also provide a review of the historical record and offer clarity in sorting through that tradition. Laie Hawaii Temple Laie Hawaii temple temples gathering Latter-day Saints Mormon Joseph F. Smith Reed Smoot Charles W. Nibley Samuel E. Woolley Ralph E. Woolley Hyrum C. Pope Harold W. Burton Walter T. Spalding Lewis A. Ramsey LeConte Stewart A.B. Wright Avard Fairbanks J. Leo Fairbanks friezes History of Christianity
148	Première détermination de la constante de Boltzmann par une méthode optique Guinet, Mickaël 23 November 2006 (has links) (PDF) Ce manuscrit présente une expérience totalement nouvelle visant à mesurer la constante de Boltzmann par une méthode de spectroscopie laser. Cette constante est déduite de la largeur à mi-hauteur d'un profil d'absorption linéaire d'un gaz d'ammoniac à température contrôlée. Sur le plan théorique, cette expérience nécessite une analyse très poussée de la forme de raie en absorption linéaire.<br />Dans ce mémoire, je décris les solutions apportées pour obtenir un faisceau laser de fréquence parfaitement contrôlée, largement accordable autour de 10 µm et d'intensité constante. Je décris également les options retenues pour le contrôle en température du gaz d'ammoniac.<br />Les résultats obtenus sont très encourageants, nous avons après seulement 2 ans déjà obtenu une première mesure de la constante de Boltzmann avec une incertitude relative de 1,9X10-4: k=1,38065(26)X10-23 J.K-1.<br />Dans ce manuscrit, je présente également plusieurs voies d'amélioration à court et moyen termes.<br />Je présente enfin une expérience de franges de Ramsey-Bordé référencée sur l'étalon primaire de fréquence localisé à Paris (au SYRTE). La chaîne de mesure absolue de fréquence atteint une résolution de 10-14 et l'incertitude pour la mesure de la frange centrale est également de l'ordre de 10-14. A moyen terme, ce système de mesure par rapport à l'étalon primaire pourra être utilisé pour contrôler la fréquence du laser à CO2 dans les futures expériences de mesure de la constante de Boltzmann. Système international d'unités <br />Constantes fondamentales <br />Spectroscopie laser <br />Absorption linéaire <br />Forme de raie <br />Laser à CO2 ultra-stable <br />Asservissement en fréquence Stabilisation en température
149	Théorie de Ramsey structurale et applications en dynamique topologique via la correspondance de Kechris-Pestov-Todorcevic Nguyen Van Thé, Lionel 09 December 2013 (has links) (PDF) Le but de ce mémoire est d'effectuer un survol de mes travaux effectués depuis janvier 2007. Le sujet d'étude se situe à l'une des intersections entre la combinatoire, la dynamique topologique et la logique via le formalisme des structures ultrahomogènes et de la théorie de Fraïssé. Ce domaine a récemment connu un essor considérable grâce à deux contributions majeures par Kechris, Pestov et Todorcevic, et par Kechris et Rosendal. Mon travail part de la première de ces contributions et se concentre autour des deux thèmes suivants : Théorie de Ramsey structurale et dynamique topologique des groupes de transformation associés. [MATH:MATH_CO] Mathematics/Combinatorics [MATH:MATH_GR] Mathematics/Group Theory [MATH:MATH_LO] Mathematics/Logic [MATH:MATH_LO] Mathématiques/Logique Théorie de Ramsey groupes topologiques et leurs actions moyennabilité extrême flots minimaux universels théorie de Fraïssé
150	Processreliabilistiska rättfärdigande som funktionalistiska förlopp: Är generalitetsproblemet ett frameproblem? Lundqvist, Johan January 2013 (has links) Först presenteras metafysisk funktionalism. En Ramseysats för smärta spelar en central roll som en implicit definition av ett mentalt tillstånd över sensorisk input och beteendemässig output. Därefter presenteras reliabilismen som en teori om kunskap. Några allmänna kunskapsteoretiska problem, samt några av reliabilismens problem presenteras. De mest relevanta problem är följande: fallet med en elak demon, klärvoajans samt Mr. Truetemp, och generalitetsproblemet. En formell och schematisk presentation ges för reliabilism som en teori för kunskap, eller möjligen tillskrivande av kunskap, och processreliabilism som en teori för epistemiskt rättfärdigande. Därefter exponeras strukturella likheter mellan funktionalism och processreliabilism. Det får anses plausibelt att det råder ett nära släktskap mellan dessa teorier då Ramseysatser för rättfärdigade trosföreställningar presenteras. Dessa analyseras sedan utifrån möjliga fall. Med ny teoretisk bakgrund prövas reliabilismens problem ånyo inom ett funktionalistisk ramverk. Nya sätt att bemöta problemen presenteras genom en analys av det Kinesiska Rummet. Det svårlösta generalitetsproblemet kan ses som ett frameproblem och hanteras med hjälp av enveloping. / Firstly, a presentation of metaphysical functionalism. A Ramsey sentence plays a central role as an implicit definition of a mental state over sensory input and behavouristic output. A presentation of reliabilism as a theory of knowledge. A summary of some general epistemological problems and some specific to reliabilism; the main ones are the evil demon, clairvoyance and Mr. Truetemp, and the generality problem. A formal and schematic presentation of reliabilism as a theory of knowlege, or possibly knowlege attribution, and process reliabilism as a theory of belief justification. Structural similarities between functionalism and process reliabilism are exposed. A close kinship between these two theories seems plausible because of the possibility to present Ramsey sentences for justified beliefs. These Ramsey sentences are then analysed over possible cases. This new theoretical background, warrents another look at problems for reliabilism. New ways to counter these problems are presented via an analysis of the Chinese Room. The elusive genrality problem is seen as a frame problem and treated using enveloping. Epistemology reliabilism process reliabilism metaphysical functionalism Ramsey sentence epistemic justification evil demon clairvoyance Mr. Truetemp generality problem the Chinese Room frame problem enveloping. Epistemologi reliabilism processreliabilism metafysisk funktionalism Ramseysats epistemiskt rättfärdigande elak demon klärvoajans Mr. Truetemp generalitetsproblem det Kinesiska Rummet frameproblem enveloping.

Search results