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1
Bayraktar, Ömer. "Quantum-Polarization State Tomography." Thesis, KTH, Tillämpad fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-185797.
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CARVALHO, JULIANA BARROS. "STATE OF POLARIZATION CONTROL IN LIGHTWAVE SYSTEM." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2012. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=20951@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE EXCELENCIA ACADEMICA
Este trabalho apresenta em sua etapa inicial os conceitos básicos de polarização da luz descritos através da Esfera de Poincaré, Vetores de Jones, Parâmetros de Stokes, Matrizes de Mueller e Fórmula da Rotação de Rodrigues. Em seguida, as diversas técnicas utilizadas para as transformações dos SOPs (States of Polarization) são introduzidas. A partir destas etapas, é apresentada a seleção, o desenvolvimento e a realização prática de um sistema capaz de ativar o controle de polarização de sinais ópticos em uma fibra monomodo. Um segundo sistema capaz de controlar sinais ópticos multiplexados em frequencia é também realizado e apresentado. Ambos os sistemas são ativados através de uma ferramenta computacional dedicada baseada na linguagem de programação gráfica LabVIEW.
This work presents initially a set of light polarization concepts using the Poincaré Sphere, Jone’s Vectors, Stoke’s Parameters, Mueller Matrices, Rodrigues’ Rotation Formula, and several SOPs (States of Polarization) transformations. Through these concepts and after a careful components selection, a SOP control system in monomode optical fiber is realized and presented. A second system able to implement the SOP control when multiplexed optical signals are employed is also realized and described. A dedicated computer tool using the software LabVIEW is developed to both systems.
3
Oliver, Sarah Louise. "Solid-state NMR studies of compatibilised polymer blends." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285638.
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Ruelas, Paredes David Reinaldo Alejandro. "Quantum state tomography for a polarization-Path Two-Qubit optical system." Master's thesis, Pontificia Universidad Católica del Perú, 2019. http://hdl.handle.net/20.500.12404/14117.
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En el área de los sistemas cuánticos abiertos, es común encontrar experimentos
y modelos teóricos en los que el sistema de interés es representado por un cubit
(sistema de dos niveles) y el entorno por otro cubit pese a que un entorno realista
debería contener muchos más grados de libertad que el sistema con el que interactúa.
No obstante, la simulación de entornos mediante un cubit es usual en la óptica
cuántica, como también lo es la realización de evoluciones de sistemas de dos cubits.
Los procedimientos utilizados para caracterizar los estados cuánticos producidos
en el laboratorio son conocidos como tomografía de estados cuánticos. Existen
algoritmos de tomografía para distintos tipos de sistemas. En esta tesis presentamos
un dispositivo interferométrico que permite generar y hacer tomografía a un estado
puro de un sistema de dos cubits: polarización y camino de propagación de la
luz. Nuestra propuesta requiere 18 mediciones de intensidad para caracterizar cada
estado. Ponemos a prueba nuestra propuesta en un experimento y contrastamos sus
resultados con las predicciones teóricas.In the field of open quantum systems, we usually find experiments and models in which the system is represented by a qubit (two-level system) and its environment by another qubit even though a realistic environment should contain many more degrees of freedom than the system it interacts with. However, these types of simulations are common in quantum optics, as are models of two-qubit system evolutions. The procedures that characterize quantum states produced in a laboratory are known as quantum state tomography. Standard tomography algorithms exist for different types of systems. In this thesis we present an interferometric device that allows us to generate and perform tomography on a pure polarization-path two-qubit state. 18 intensity measurements are required for characterizing each state. We test our proposal in an experiment and compare the results with the theoretical predictions.
Tesis
5
Bigelow, Nathan S. "Representation in state legislatures searching for responsiveness in an age of polarization /." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3438.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2006.Thesis research directed by: Government and Politics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
6
Barnes, Alexander B. (Alexander Benjamin). "High-resolution high-frequency dynamic nuclear polarization for biomolecular solid state NMR." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/65263.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, June 2011.Vita. Cataloged from PDF version of thesis.
Includes bibliographical references.
Dynamic Nuclear Polarization (DNP) has exploded in popularity over the last few years, finally realizing its potential to overcome the detrimental lack of sensitivity that has plagued performing NMR experiments. Applied to magic angle spinning (MAS) experiments, this renaissance of DNP has been primarily driven by the development of instrumentation; namely gyrotron oscillators as high-power stable microwave power sources and the NMR probes and associated equipment required to spin samples routinely below 100 Kelvin. The first three chapters of this thesis provide an overview of the theory, instrumentation, and applications of DNP. Chapter 1 introduces the magnetic resonance Hamiltonian with a focus on interactions that are necessary to control in order to obtain high-resolution DNP spectra. Chapters 2 and 3 are published reviews of DNP. Whereas Chapter 2 targets magnetic resonance spectroscopists, Chapter 3 is intended for an electric engineering audience. Both reviews are included as the associated depth and coverage of the topics are complementary and lead to a better understanding of DNP. The later chapters describe in detail advancements in probe, cryogenics, and gyrotron technology required to perform DNP MAS experiments, as well as the gains in sensitivity and resolution such instrumentation has permitted. Of particular importance is the development of a cryogenic sample ejection system that resulted in exquisite resolution of spectra recorded <100 K, both of crystalline peptide and the active site of membrane proteins. Such developments in instrumentation and demonstrations of resolution go towards overturning a long-held stance in the field that DNP would always suffer from broadened, unresolved spectra. Such techniques also allow us to investigate site specific dynamics of a crystalline peptide, the high resolution SSNMR structure of which is discussed in Chapter 3. DNP and the developed instrumentation is also leveraged to measure inter-atomic distances in the active site of a membrane protein with sub-angstrom precision. Chapters 7 describes the calculation of the microwave field strength across the sample in a MAS DNP probe and introduces strategies to increase it. Finally Chapter 8 introduces a major advance in the microwave source technology associated with DNP experiments. Detailed designs of a novel 250 GHz gyrotron oscillator are shown and experiments demonstrate a continuous broad 3 GHz bandwidth with >10 W across the band, which results in substantially improved DNP performance.
by Alexander B. Barnes.
Ph.D.
7
Conroy, Daniel William. "Structural Studies of Biomolecules by Dynamic Nuclear Polarization Solid-State NMR Spectroscopy." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555428362333615.
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Karim, Jena. "Polarization of political culture : Islam and Pakistan, 1958-1988." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=83114.
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This study examines the relationship between Islam and political culture in Pakistan in the four decades following its naissance. It assesses the validity of the argument that a polarity has emerged in the Pakistani political culture, consisting of Islamism and Islamic modernism. In the case of Pakistan, Islamism refers to the use of the primary sources of Islam law, the Qur'an, hadith, and sunnah, in crafting both policy and political institutions. Islamic modernism refers to the systematized use of these primary sources as well as other (external) sources, adjusted for contemporary circumstances. These ideologies, as defined here, are gleaned from the discourse of a Pakistani ideologues, Sayyid Abu'l A 'la Mawdudi and Fazlur Rahman. It examines the thought of Mawdudi and Rahman as the discursive backdrop to the polarity of political culture. It then provides analysis of three regimes which exacerbate this polarity. They include the Islamic modernist regime of Ayub Khan, from 1958 to 1969, the quasi-Islamist regime of Zulfiqar Ali Bhutto, from 1971 to 1977, and finally the Islamist regime of General Zia ul-Haq, from 1977 to 1988.
9
Laage, Ségolène. "High-resolution solid-state NMR for proteins." Lyon, Ecole normale supérieure, 2010. http://www.theses.fr/2010ENSL0583.
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La RMN a récemment prouvé son potentiel en biologie structurale. Cette thèse décrit les méthodes que nous avons développées pour l’étude de protéines par RMN du solide à haute résolution. Après une présentation des récents progrès du domaine, nous présentons les améliorations liées à l’utilisation de la rotation à l’angle magique à très haute vitesse, notamment les techniques de découplage hétéronucléaire et de polarisation croisée à basse puissance, appliquées aux cas de la Superoxide Dismutase (SOD) et de la protéine GB1. Nous détaillons ensuite les perspectives émergeant dans l’utilisation des couplages J, avec trois nouvelles séquences. La J-CHHC renseigne sur les distances entre protons, le bloc S3E améliore résolution et sensibilité en effectuant du découplage J, et l’INADEQUATE-S3E combine transfert de polarisation par couplage J et découplage J. Nous donnons enfin des perspectives de mesure de longues distances par l’exploitation des propriétés paramagnétiques de la Cu(II) SODSolid-state NMR recently proved its potential for structural biology. This thesis details metods we developed for high resolution NMR of nanocrystalline proteins. After an introductory presentation of the recent advances in solid-state NMR of bio-systems, we present the improvements we proposed in the ultra-fast magic-angle spinning regime, notably low-field heteronuclear decoupling and low-field cross-polarization. We demonstrate them with the study of the Superoxide Dismutase (SOD) and the protein GB1. We then focus on the perspectives arising for J-couplings in proteins by presenting three new sequences. The J-CHHC sequence probes 1H-1H distances encoded in 13C-13C correlation experiments. The S3E block improves resolution and sensitivity by performing J-decoupling, and the INADEQUATE-S3E combines J-based transfer of polarization and J-decoupling. We finally give perspectives to probe long-range structural constraints with data exploiting the paramagnetic properties of Cu(II)-SOD
10
Woodard, Niki L. "Red state, blue state, red news, blue news." Connect to this title online, 2006. http://hdl.handle.net/1961/3639.
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Sauvée, Claire. "New dinitroxides as efficient polarizing agents for Dynamic Nuclear Polarization solid-state NMR." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4739.
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Depuis sa découverte, la spectroscopie de Résonance Magnétique Nucléaire (RMN) a permis de grandes avancées scientifiques dans de nombreux domaines allant de la physique à la médecine. L'inconvénient majeur de la RMN est sa faible sensibilité intrinsèque, due à la très faible polarisation des spins nucléaires. Au cours de ces 20 dernières années, la Polarisation Dynamique Nucléaire (PDN) s'est développée comme technique très prometteuse permettant d'augmenter la polarisation de spin nucléaire, et l'intensité des signaux en RMN liquide ou solide de plusieurs ordres de grandeur. Dans les mêmes conditions expérimentales, la polarisation de spin de l'électron est beaucoup plus grande que la polarisation de spin nucléaire et la PDN permet le transfert de cette forte polarisation à partir d'un agent de polarisation paramagnétique (habituellement un radical libre organique) vers les noyaux avoisinants. L'augmentation de l'intensité du signal RMN (I) est caractérisé par un facteur d'exaltation ε=I(μw ON)/I(μw OFF).L'objectif principal de cette thèse est la synthèse d'agents de polarisation, de type dinitroxyde, solubles dans l'eau et très efficaces pour des expériences de MAS ssNMR/PDN. Nous avons préparé une large série de dérivés du bTurea solubles dans l'eau et leurs performances PDN ont été évaluées à différent champs magnétiques. En remplaçant les groupements méthyl des fonctions TEMPO par des cycles pyranyl, ainsi qu'en introduisant des chaînes PEG sur le linker urée, AMUPol (ε=247) et PyPolPEG2OH (ε=303) ont entre autres été obtenus. Ce sont actuellement les agents de polarisation les plus efficaces pour des expériences de MAS ssNMR/PDN en milieux aqueuxNowadays, Nuclear Magnetic Resonance (NMR) spectroscopy has become a very powerful technique that can be used to address a wide range of problems, ranging from physics to medicine. The major limitation of NMR is its intrinsic low sensitivity, resulting from the very small nuclear spin polarizations observed even at high magnetic fields. During the last two decades, Dynamic Nuclear Polarization (DNP) has emerged as a very promising approach to enhance NMR signal intensities of solids and liquids by several orders of magnitude. All things being equal, electron spin polarization is much higher than nuclear spin polarization and DNP exploits the microwave-driven transfer of polarization from a paramagnetic polarizing agent (usually an added exogenous organic free radical) to the surrounding nuclei. The enhancement of NMR signal intensities (I) is characterized by the enhancement factor ε=I(μw ON)/I(μw OFF). The main objective of this PhD thesis was the development of new water-soluble dinitroxides, highly efficient polarizing agents for MAS solid-state NMR/DNP applications. We have designed and prepared a large series of water-soluble bTurea (TEMPO-N(H)-C(O)-(H)N-TEMPO), derivatives, and their DNP performance was tested at different magnetic fields (mainly 9.4 T). Replacing the methyl groups of TEMPO moieties with pyranyl rings, and introducing PEG chains on the urea linker we obtained, among others, two derivatives, AMUPol (ε = 247) and PyPolPEG2OH (ε = 303) which are currently the most efficient water-soluble polarizing agents for MAS ssNMR/DNP experiments for aqueous media
12
Sosnovsky, Denis V., Gunnar Jeschke, Jörg Matysik, Hans-Martin Vieth, and Konstantin L. Ivanov. "Level crossing analysis of chemically induced dynamic nuclear polarization: Towards a common description of liquid-state and solid-state cases." AIP Publishing, 2016. https://ul.qucosa.de/id/qucosa%3A31179.
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Chemically Induced Dynamic Nuclear Polarization (CIDNP) is an efficient method of creating
non-equilibrium polarization of nuclear spins by using chemical reactions, which have radical pairs as
intermediates. The CIDNP effect originates from (i) electron spin-selective recombination of radical
pairs and (ii) the dependence of the inter-system crossing rate in radical pairs on the state of magnetic
nuclei. The CIDNP effect can be investigated by using Nuclear Magnetic Resonance (NMR) methods.
The gain from CIDNP is then two-fold: it allows one to obtain considerable amplification of NMR
signals; in addition, it provides a very useful tool for investigating elusive radicals and radical pairs.
While the mechanisms of the CIDNP effect in liquids are well established and understood, detailed
analysis of solid-state CIDNP mechanisms still remains challenging; likewise a common theoretical
frame for the description of CIDNP in both solids and liquids is missing. Difficulties in understanding
the spin dynamics that lead to the CIDNP effect in the solid-state case are caused by the anisotropy
of spin interactions, which increase the complexity of spin evolution. In this work, we propose to
analyze CIDNP in terms of level crossing phenomena, namely, to attribute features in the CIDNP
magnetic field dependence to Level Crossings (LCs) and Level Anti-Crossings (LACs) in a radical
pair. This approach allows one to describe liquid-state CIDNP; the same holds for the solid-state
case where anisotropic interactions play a significant role in CIDNP formation. In solids, features
arise predominantly from LACs, since in most cases anisotropic couplings result in perturbations,
which turn LCs into LACs. We have interpreted the CIDNP mechanisms in terms of the LC/LAC
concept. This consideration allows one to find analytical expressions for a wide magnetic field range,
where several different mechanisms are operative; furthermore, the LAC description gives a way to
determine CIDNP sign rules. Thus, LCs/LACs provide a consistent description of CIDNP in both
liquids and solids with the prospect of exploiting it for the analysis of short-lived radicals and for
optimizing the polarization level.
13
Huntington, Amy. "Polarization correlation study of the 2pâµ3p ³D₃ state of neon excitedbyelectrons." Thesis, University of Newcastle Upon Tyne, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445619.
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Rumbaugh, Scott Hamilton. "Endless state-of-polarization control for coherent optical communication systems using nematic liquid crystals." PDXScholar, 1989. https://pdxscholar.library.pdx.edu/open_access_etds/4145.
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One of the obstacles to coherent fiber-optic communications is the unpredictable polarization drift which necessitates the use of an active polarization controlling system to match the polarizations of the signal and local oscillator. The polarization match must be maintained during the reset of any of the finite range components to prevent loss of data. We present a novel and practical system which uses three liquid crystal devices for the polarization matching process. Also, the required reset control algorithm and its derivation are described in detail.
15
Yilmaz, Umit Oktay. "The Polarization Properties Of The Final State Particles In The Rare Radiative B-meson Decay." Phd thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606100/index.pdf.
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A general analysis of the photon and lepton polarizations in the rare Bs →
&
#61543
l+l- decay by using the most general model independent form of the effective Hamiltonian is presented. The total and the differential branching ratios for these decays, when photon is in the positive and negative helicity states, are studied. The sensitivity of "
photon polarization asymmetry"
and the longitudinal, transverse and normal polarization asymmetries of final state leptons, as well as lepton-antilepton combined asymmetries in Bs &
#8594
&
#61543
l+l- decay to the new Wilson coefficients are also investigated. It is shown that all these physical observables are very sensitive to the existence of new physics beyond SM and their experimental measurements can give valuable information about it.
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Liou, Anthony En-Lee. "Characterization of fading and polarization state dispersion on fixed wireless links in suburban macrocell environments." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/14716.
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Growing use of point-to-multipoint fixed wireless networks to support network access and system automation in suburban macrocell environments has prompted regulators to re-allocate various bands between 200 MHz and 2 GHz to such applications. Links in such networks are usually obstructed by
buildings and foliage and are classified as non-line-of-sight. Although it is well-known that such links are susceptible to fading caused by windblown trees and foliage, most past efforts to characterize fading
on such links have focused on frequency bands at 1.9 GHz and above. Here, we study how the depth and rate of fading in the 220, 850 and 1900 MHz bands vary with distance and time-averaged wind speed in a representative macrocell environment. We observed that while the signal fading is relatively severe at 1.9GHz, the depth of fading drops rapidly as the carrier frequency decreases. However, the rate of
fading is effectively independent of either the average wind speed or the carrier frequency. Further, polarization diversity on narrowband wireless links has traditionally been characterized in terms of the fading statistics and the cross-correlation between the fading signals on each branch. A complementary
approach, which is independent of the polarization states of the diversity receiving antennas, is to
characterize the manner in which the polarization states observed at the receiver disperse across the Poincaré sphere. First, by simulation, we show that when the fading signals observed on orthogonal
diversity branches follow ideal Ricean statistics, the distribution of polarization states on the Poincaré sphere is well-approximated by a Fisher distribution whose concentration parameter is: (1) determined by the corresponding Ricean K-factors and the cross-correlation coefficient between the diversity
branches, and (2) a good indicator of the level of cross-polar discrimination (XPD). Finally, from measurements collected in a typical suburban macrocell environment at 1.9GHz, we show that: (1) the means of the polarization state distributions also tends to follow a Fisher distribution and (2) the Fisher concentration parameter is negatively correlated with the average wind speed. Development of a model applicable to a broad range of environments will require additional data from other sites and
measurement configurations.
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Wang, Shenshen. "Theoretical approach to circular-polarization-independence of microwave-induced resistance oscillations and zero resistance state /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202007%20WANG.
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Ramanathan, Chandrasekhar. "Biomedical solid state NMR : an ADRF cross polarization study of calcium phosphates and bone mineral." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38389.
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Chen, Kezheng. "Origin of Polarization Behavior in All-Solid-State Lithium-Ion Battery Using Sulfide Solid Electrolyte." Kyoto University, 2018. http://hdl.handle.net/2433/235998.
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Bajaj, Vikram Singh. "Dynamic nuclear polarization in biomolecular solid state NMR : methods and applications in peptides and membrane proteins." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40874.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2007.Includes bibliographical references.
Solid state NMR can probe structure and dynamics on length scales from the atomic to the supramolecular. However, low sensitivity limits its application in macromolecules. NMR sensitivity can be improved by dynamic nuclear polarization (DNP), in which electron polarization is transferred to nuclei. We present applications of magic angle spinning NMR that demonstrate its utility for the determination of structure at atomic resolution. We then present new techniques and instrumentation for DNP that permit these methods to be applied to larger systems such as membrane proteins. These applications rest on several advances in instrumentation: millimeter-wave sources and conduits of power to the sample; low-temperature MAS probes incorporating millimeter-wave transmission; cryogenics and pneumatic control systems. We describe a 380 MHz DNP spectrometer incorporating a 250 GHz gyrotron oscillator and present the theory and operation of a 460 GHz gyrotron at the second harmonic of electron cyclotron resonance. We have applied DNP to study trapped photo cycle intermediates of the archael membrane protein bacteriorhodopsin, a light-driven transmembrane ion pump.
(cont.) We have observed the K photointermediate for the first time by NMR and found unexpected conformational heterogeneity in the L intermediate. With multidimensional correlation spectroscopy, we have assigned active site resonances in conformational mixtures of photointermediates of [U-13C,'SN]-bR with high sensitivity. By using non-linear sampling of indirect dimensions, we have observed transient product of K accumulation. We present frequency-selective experiments for amino acid-selective assignments and the measurement of heteronuclear distances and torsion angles in [U-13C, N]-bR and discuss the relevance of these results to its photocycle. In addition, we describe several applications of solid state NMR, including a study of dynamic and structural phase transitions in peptides and proteins near the canonical glass transition temperature. We present resonance width experiments that can be used to measure homonuclear and heteronuclear dipolar couplings in uniformly labeled solids.
(cont.) Finally, we discuss applications to amyloid fibrils, which are protein aggregates that are implicated in diseases of protein misfolding. We report the atomic resolution structure of the disease-associated L 111M mutant of TTR105-115 in an amyloid fibril, and information about the supramolecular structure of fibrils from WT TTRos05115.
by Vikram Singh Bajaj.
Ph.D.
21
Kučera, Petr. "Polarizační nedokonalosti světla v interferometrii." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-233460.
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Disertační práce pojednává o polarizačních nedokonalostech optických komponentů, které jsou využívány ke kontrole a k transformaci polarizačního stavu světla. Získané teoretické výsledky jsou pak využity ve vybraných aplikacích, jež ke své činnosti využívají právě polarizace světla. Konkrétně se jedná o zařízení měřící vibrace oscilujících objektů, dále o interferenční měření dvojlomu v transparentních materiálech a konečně, o vybraná témata z optické kvantové komunikace.
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Wang, Lei. "Ultrafast Excited State Investigation of Ruthenium and Osmium Polypyridyl SulfoxideComplexes and BOPHY Dyes." Ohio University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1433864223.
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Warren, Glen Andrew. "Induced final state proton polarization in neutral pion electroproduction near the [delta](1232) resonance at Q² = -0.126 GeV²/c²." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43306.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1997.On t.p. "[delta]" appears as the lower case Greek letter.
Includes bibliographical references (p. 210-[211]).
by Glen Andrew Warren.
Ph.D.
24
Bahl, Anand, Jared K. Wahlstrand, Sina Zahedpour, Howard M. Milchberg, and Miroslav Kolesik. "Nonlinear optical polarization response and plasma generation in noble gases: Comparison of metastable-electronic-state-approach models to experiments." AMER PHYSICAL SOC, 2017. http://hdl.handle.net/10150/626054.
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The nonlinear polarization response and plasma generation produced by intense optical pulses, modeled by the metastable-electronic-state approach, are verified against space-and-time resolved measurements with single-shot supercontinuum spectral interferometry. This first of a kind theory-experiment comparison is done in the intensity regime typical for optical filamentation, where self-focusing and plasma generation play competing roles. Excellent agreement between the theory and experiment shows that the self-focusing nonlinearity can be approximated by a single resonant state. Moreover, we demonstrate that inclusion of the post-adiabatic corrections, previously tested only in theoretic models, provides a viable description of the ionization rate in real gases.
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Sarrouj, Hiba. "DNP/solid state NMR probehead for the investigation of oriented membranes." Phd thesis, Université de Strasbourg, 2014. http://tel.archives-ouvertes.fr/tel-01038015.
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Helical membrane proteins comprise one third of the expressed proteins encoded in a typical genome. Other membrane proteins are typically beta sheets. Their function varies from pore formation, signaling to antimicrobial activity. They are also capable of transporting large cargo such as proteins or nucleic acids across the cell membrane. Recently, peptides have emerged as promising tools in drug delivery. Membrane proteins can be synthesized chemically or expressed and isotopically labeled in bacteria, isolated, purified and reconstituted into fully hydrated lipid bilayers. The bilayer orientation is kept mechanically by putting them between glass plates. While interacting with these bilayers they exhibit a variety of configurations depending on the lipids composition and thickness. Solid-state Nuclear Magnetic Resonance (NMR) on oriented bilayers is one way to access the topology of peptides associated with phospholipid membranes. Oriented membrane protein are difficult to study with analytical techniques because of their poor solubility outside the lipid membrane, difficulty of expression in bacteria in big quantities, difficulty to crystallize, and they are too large for solution NMR study. The intensity of an NMR signal depends on several factors such as polarization P and magnetic field magnitude B0. One of the major drawbacks of NMR spectroscopy is low sensitivity. This is caused by the small magnetic moment of the nuclear spins which results in a modest Zeeman splitting of the nuclear spin energy levels and therefore in a limited Boltzmann Polarization. The aim of this project is to obtain a better signal from membrane proteins. Thus a Low temperature (LT) solid state NMR with Dynamic Nuclear Polarization (DNP) probe head was created. DNP is an ingenious technique that is used to transfer polarization from highly polarized targets to less polarized nuclei using microwave irradiation. Microwaves will excite selectively the electron spins which will transfer their polarization to the pool of proton nuclei, the proton NMR signal can be enhanced by 660 times. A probe head for DNP enhanced solid state NMR at 100 K and 9.4 T is described. A probe head includes the mechanical piece that holds the sample in the magnetic center of the NMR magnet. It is a tunable antenna that irradiates and detects the rf fields used in NMR. The centerpiece of the probe is the solenoidal or saddle coil surrounding the sample. The feasibility of such a DNP experiment is proven on magic angle oriented sample spinning. These experiments are conducted on oriented samples wrapped into a rotor. Through their orientation with regards to B0 is lost, enhancement values as high as 17 are obtained. [...]
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Wang, Xiaoling. "MRI and NMR Investigations of Transport in Soft Materials and Explorations of Electron-Nuclear Interactions for Liquid-State Dynamic Nuclear Polarization." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/75067.
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The first part of this dissertation (Chapters 1 to 4) describes the use of magnetic resonance techniques for polymeric material characterizations in solutions, with emphasis on methods utilizing magnetic field gradients - magnetic resonance imaging (MRI) and pulsed-field-gradient (PFG) NMR. The second part (Chapter 5) presents enhancements to dynamic nuclear polarization, an intensity enhancement approach for magnetic resonance techniques.
In Chapter 2, I illustrate a characterization method to quantify free polymer chain content in a polymer/DNA complex (polyplex) formulation via one-dimensional proton NMR experiments. This assessment of free polymer quantity has critical impacts on in vivo gene transfection efficiency, cellular uptake, as well as toxicity of polycationic gene delivery vectors. Specifically, I investigated the complexation properties of three different polymeric "theranostic" agents, which combine an imaging functionality on the polymer as well as a DNA/RNA complexation component. These agents are under development to allow real time clinical monitoring of drug delivery and efficacy using MRI. Our NMR method provides simple and quantitative assessment of free and DNA-complexed polymers, including the actual polymer amine to DNA phosphate molar ratio (N/P ratio) within polyplexes. The NMR results are in close agreement with the stoichiometric number of polymer/DNA binding obtained by isothermal titration calorimetry. The noninvasive nature of this method allows broad application to a range of polyelectrolyte coacervates, for understanding and optimizing polyelectrolyte complex formation.
Chapter 3 demonstrates a time-resolved MRI approach for measuring diffusion of drug-delivery polymeric nanoparticles on mm to cm scales as well as monitoring nanoparticle concentration distribution in bulk biological hydrogels. Our results show that as the particle size and surface charge become larger, collagen gel at tumor relevant concentration (1.0 wt.%) presents a more significant impediment to the diffusive transport of negatively charged nanoparticles. These results agree well with those obtained by fluorescence spectroscopies (neutral or slightly positively charged diffusing particles) as well as the proposed electrostatic bandpass theory of tumor interstitium (negatively charged particles). This study provides fundamental information for the design of polymeric theranostic vectors and carries implications that would benefit the understanding of nanoparticle transport in solid tumors. Furthermore, this work takes a significant step toward developing quantitative and real time in vivo monitoring of clinical drug delivery using MRI.
Chapter 4 addresses the application of PFG-NMR for the determination of weight-average molar mass (Mw) for polyanions that have anti-HIV activity through the measurement of polymer diffusion coefficients in solutions. The effective characterization of molecular weights of polyelectrolytes has been a general and growing problem for the polymer industry, with no clear solutions in sight. In this study, we obtained the molar masses (Mw) for two series of sulfonated copolymers using sodium polystyrene sulfonate samples as molecular weight standards. PFG-NMR has notable advantages over conventional techniques for the characterization of charged polymers and shows great promise for becoming an effective alternative to chromatography methods.
Chapter 5 is devoted to experimental and theoretical studies of liquid state dynamic nuclear polarization (DNP) via the Overhauser effect. Based on the adventurous work done by previous Dorn group members, we show that for 1H-nuclide-containing systems, the dipolar DNP enhancement can be significantly improved by decreasing the correlation time of the interaction by utilizing a supercritical fluid (SF CO2) which allows for greater dipolar enhancements at higher magnetic fields. For molecules containing the ubiquitous 13C nuclide, we show that previously unreported sp hybridized (H-C) alkyne systems represented by the phenylacetylene-nitroxide system exhibit very large scalar-dominated enhancements. Furthermore, we show for a wide range of molecular systems that the Fermi contact interaction can be computationally predicted via electron-nuclear hyperfine coupling and correlated with experimental 13C DNP enhancements. For biomedical applications, the enhancement of metabolites in SF CO2 followed by rapid dissolution in water or biological fluids is an attractive approach for future hyperpolarized NMR and MRI applications. Moreover, with the aid of density functional theory calculations, solution state DNP provides a unique approach for studying intermolecular weak bonding interaction of solutes in normal liquids and SF fluids.Ph. D.
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Berruyer, Pierrick. "Three-Dimensional Structure Determination of Surface Sites with Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEN042/document.
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La capacité à déterminer les structures moléculaires en trois dimensions à partir de monocristaux par des méthodes de diffraction a transformé la chimie des matériaux. Le problème de la détermination de structure est en grande partie non résolu, en particulier si le système étudié est situé à une surface et n'a pas de périodicité, comme dans la plupart des matériaux fonctionnels actuels. La Résonance Magnétique Nucléaire (RMN) à l’état solide serait une méthode de choix pour caractériser les surfaces mais la limite de détection de la RMN est beaucoup trop faible pour permettre à la RMN de caractériser les surfaces. L’introduction récente d’une nouvelle approche utilisant la Polarisation Dynamique Nucléaire (DNP) pour améliorer la sensibilité de la RMN des surfaces (DNP SENS) permet à présent de réaliser des expériences qui étaient totalement impossible il y a quelques années encore. Plus particulièrement, grâce à la méthode DNP SENS, les présents travaux de thèse aboutissent à la première structure tridimensionnelle d’un complexe organométallique supporté sur silice, avec une précision de 0,7 Å. De nombreux aspects de l’expérience DNP SENS ont été exploré. Le transport de de l’hyperpolarisation par diffusion de spin est primordial et un modèle numérique dans les matériaux mésoporeux a été développé. De plus, une nouvelle matrice aqueuse se basant sur des gels polyacrylamides a été mise au point et utilisée pour la caractérisation par RMN de nanoparticules permettant ainsi d’étendre les domaines d’application de DNP SENS. Enfin les premières expériences RMN DNP combinant hauts champs magnétiques et haute fréquence de rotation d’échantillon sont présentéesThe ability to understand the properties of chemical systems relies on their detailed description at the molecular level. Over the last century, several methods based on X-ray diffraction have allowed a structure-based understanding of many materials. However, several key questions often remain unanswered. In particular when the system under investigation is located on a surface. Although an extensive range of surface-sensitive methods are available for surface science and give valuable information, they only lead to a partial understanding of surfaces at the molecular level. Moreover, these methods are not compatible with all kinds of materials and usually require the use of a model and pristine surface. Solid-State NMR would be a method of choice to characterize surfaces. However, the approach suffers from its intrinsically low sensitivity and this is strongly emphasize in the case of surfaces where the atoms of interest are diluted in the matrix. Dynamic Nuclear Polarization (DNP) applied to surfaces (SENS) recently emerged as a very promising method to characterize surface sites. It offers a dramatic enhancement of NMR sensitivity and DNP applied to materials has led to many examples in the last ten years. In the present thesis, I have shown that DNP SENS, in combination with EXAFS, allowed the detailed 3D structure determination of the silica-supported organometallic complex determined with a precision of 0.7 angstroms. In parallel, some experimental aspect of DNP SENS have been explored. A spin diffusion has been developed to understand diffusion of hyperpolarization in porous media. A new aqueous DNP matrix, coined DNP Jelly, has been developed to characterize nanoparticles and thus expanding experimental range of DNP SENS. Finally, the first experiment of DNP NMR at fast magic angle spinning (up to 40 kHz) and high field are reported
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De, Neef Alexandre. "Processing of PVDF/PMMA Films by Melt-State Extrusion-Casting : Impact of PMMA on Beta-Phase Crystallization and Related Piezo/Ferroelectric Properties." Electronic Thesis or Diss., Ecole nationale supérieure Mines-Télécom Lille Douai, 2019. http://www.theses.fr/2019MTLD0018.
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Ces travaux de doctorat visent à étudier la mise en forme de matériaux polymères piézoélectriques via des procédés de plasturgie pour des applications émergentes (capteurs et µ- générateur d’énergie, notamment pour le domaine des objets connectés autonomes en énergie). Les travaux ont été ciblés sur le poly(fluorure de vinylidène) (PVDF) en raison de ses performances piézoélectriques élevées. La structure/phase cristalline polaire β du PVDF est nécessaire mais peut s’obtenir par étirage ou copolymérisation. Ces travaux proposent une approche alternative de type « mélange de polymères » par extrusion en voie fondue pour modifier la cristallinité du PVDF via l’addition du poly(méthacrylate de méthyle) (PMMA), possédant un caractère miscible et un impact sur la cristallisation en phase β du PVDFThis PhD work aims to study the casting of piezoelectric polymer materials via plastics processes for emerging applications (sensors and µ-energy generator, especially for the domain of autonomous connected objects in energy). Work has been focused on polyvinylidene fluoride (PVDF) because of its high piezoelectric performance. The crystalline polar β structure/phase of PVDF is necessary but can be obtained by stretching or copolymerization. This work proposes an alternative approach of the "polymer blend" type by melt-state extrusion to modify the crystallinity of PVDF via the addition of poly (methyl methacrylate) (PMMA), having a miscible character and an favorable impact on crystallization in β-phase of PVDF
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Angsana, Julianty. "The role of syndecan-1 in the resolution of chronic inflammatory responses." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/52947.
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Inflammation is an integral part of the body defense mechanism that occurs in vascularized tissue in response to harmful stimuli that is perceived as being a threat to tissue homeostasis. It is a complex physiological host response that is designed to neutralize and eliminate harmful agents, initiate tissue healing, and orchestrate a return to tissue homeostasis. While inflammation is designed to be an acute event that resolves following the elimination of harmful stimuli and tissue healing, there are instances where inflammation fails to resolve and instead evolves into chronic inflammation. It is now well understood that ongoing inflammation can serve as the underlying cause of many chronic inflammatory diseases, including atherosclerosis. In fact, one of the most pressing issues that is currently faced in the field of inflammation research, one that has also become the focus of numerous ongoing investigations, is how to turn this excessive, unwarranted and undesirable inflammation response off. Once thought to be a passive and simple process, resolution is now understood to be an active and complex process that is orchestrated by various inflammatory mediators, signaling pathways and biophysical processes. The discovery of novel biosynthetic pathways that turn on the pro-resolution signals has lead to a surge in research aimed at taking a closer look at processes that can stimulate the resolution of inflammation. While major advances in the field have resulted in a better understanding of the proactive nature of resolution, many of the mechanisms involved are still unknown. To date, the repertoire of chemokine receptors that participate in macrophage clearance during resolution, for the most part, remain unidentified. Overall, there is a growing appreciation that the discovery of mechanisms involved in the resolution responses can lead to the development of novel therapeutic approaches to resolve many chronic inflammatory diseases. Syndecan-1 (Sdc-1), a member of a family of cell surface proteoglycans, has been previously shown to regulate events relevant to tissue repair and chronic injury responses. Macrophage Sdc-1 expression during inflammation has been reported to be protective in various inflammatory models. Given these observations, we hypothesize that Sdc-1 expression on macrophages is a critical component of an anti-inflammatory, pro resolution program necessary for the successful resolution of inflammatory response. In this dissertation, we report the presence of a unique population of macrophages expressing Sdc-1 that are present within the vascular wall of mice undergoing atherosclerosis. Consistent with previous publications, the presence of Sdc-1 expressing macrophages was found to limit atherosclerosis progression. In addition, Sdc-1 expression on macrophages was associated with anti-inflammatory M2 polarization state and high intrinsic motility. Macrophage Sdc-1 expression was also linked with efferocytosis and enhanced macrophage egress from the site of inflammation to the draining lymphatic network. Moreover, we discovered that the chemokine receptor CXCR4, which was found on Sdc-1 expressing macrophages, was also involved in macrophage egress during inflammation resolution. In summary, while the overall mechanism regulating resolution processes is still unknown, our work has managed to identify two components that are involved in the process: macrophage Sdc-1 and CXCR4. Collectively, these results reinforce the physiological significance of macrophage efferocytosis and macrophage motility as endogenous modulators of the inflammatory response.
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Hauenstein, Florian [Verfasser], Wolfgang [Akademischer Betreuer] Eyrich, and Erhard [Akademischer Betreuer] Steffens. "Proton-Lambda Final State Interaction and Polarization Observables Measured in the →pp → pKLamda Reaction at 2.7GeV/c Beam Momentum / Florian Hauenstein. Gutachter: Wolfgang Eyrich ; Erhard Steffens." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2014. http://d-nb.info/1075834945/34.
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Enkin, Nikolay [Verfasser], Marina [Akademischer Betreuer] [Gutachter] Bennati, Markus [Gutachter] Zweckstetter, and Jörg [Gutachter] Enderlein. "Fullerene-Nitroxide Derivatives as Potential Polarizers for Dynamic Nuclear Polarization (DNP) in Liquid State / Nikolay Enkin ; Gutachter: Marina Bennati, Markus Zweckstetter, Jörg Enderlein ; Betreuer: Marina Bennati." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2016. http://d-nb.info/1113875496/34.
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Mantheni, Dhruthiman Reddy. "NOVEL SOLIS STATE PROPERTIES OF DRUGS, POLYMERS AND VARIOUS CHEMICALS BY THERMAL AND ANALYTICAL TECHNIQUES." Cleveland State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=csu1356019701.
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Lenoir-Capello, Rachel. "Specific labeling strategies for new developments in liquid state protein NMR." Thesis, Sorbonne université, 2020. https://accesdistant.sorbonne-universite.fr/login?url=http://theses-intra.upmc.fr/modules/resources/download/theses/2020SORUS056.pdf.
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La résonance magnétique nucléaire (RMN) fournit des informations structurelles et dynamiques précieuses à l'échelle atomique, cependant, la faible sensibilité et résolution des signaux empêchent l’étude d'objets moléculaires plus importants. Nous présentons 3 stratégies de marquage isotopique pour différentes expériences RMN des protéines en solution et démontrons leur potentiel pour l'étude structurale des biomolécules. Parmi les stratégies envisagées, 2 utilisent l'expression in vitro pour obtenir des protéines marquées sélectivement sur un groupe chimique et/ou acide aminé dans un environnement perdeutéré. Avec l’utilisation de séquences d'impulsions TROSY, ces échantillons ont permis des gains spectraux importants lorsque ils étaient spécifiquement marqués sur des groupes amide ou sur le méthylène des glycines tout en maintenant un taux de deutération élevé sur les autres fonctions chimiques des protéines. La troisième stratégie de marquage protéique utilise des protocoles in vivo pour des applications RMN innovantes: l'hyperpolarisation de noyaux en solution qui augmente leur sensibilité de plusieurs ordres de grandeur. La durée de vie de cette hyperpolarisation est régie par le temps de relaxation longitudinale des noyaux, qui est réduit pour les protéines à température ambiante. En isolant les noyaux d'intérêt dans un environnement perdeutéré, les interactions dipolaires créées par les protons voisins sont éliminées et les noyaux hyperpolarisés relaxent beaucoup plus lentement. L'hyperpolarisation d'un petit domaine protéique a été entreprise avec succès mais les conditions de dissolution doivent encore être améliorées pour conserver une phase aqueuse homogèneNuclear Magnetic Resonance (NMR) provides valuable structural and dynamic information at the atomic scale, however, the low sensitivity and resolution of signals rapidly preclude investigations of larger molecular objects. We present three isotopic labeling strategies for different protein-solution NMR experiments and demonstrate their potential for the structural study of biomolecules in solution. Among the strategies considered, two are based on the use of in vitro protein expression to obtain selectively labeled proteins of a certain chemical group and/or amino acid in a perdeuterated environment. Perdeuteration is essential for the optimal use of Transverse Relaxation Optimized Spectroscopy pulse sequences. They allowed significant spectral gains when samples were specifically labeled on amide groups or on the methylene of glycines while maintaining a very high rate of deuteration on the other chemical functions of the proteins. The third protein labeling strategy employed is based on in vivo protocols but used in innovative NMR applications: a technique of hyperpolarization of nuclei in solution which increases their sensitivity by several orders of magnitude. The lifetime of this hyperpolarization is governed by the longitudinal relaxation time of nuclei, which are reduced for proteins at room temperature. By isolating the nuclei of interest in a perdeuterated environment, dipolar interactions created by neighboring protons were eliminated and hyperpolarized nuclei relaxed much more slowly. Hyperpolarization of a small protein domain was successfully undertaken at 1K but the dissolution conditions need to be improved in order to preserve a homogeneous aqueous phase
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Algadey, Tarig. "Investigation of Negative Refractive Index in Isotropic Chiral Metamaterials Under First and Second-Order Material Dispersion With and Without Conductive Loss." University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1460819619.
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Almeida, Rutileia Lima. "A formação regional do bico do papagaio: regionalização e polarização." Universidade Federal de Goiás, 2010. http://repositorio.bc.ufg.br/tede/handle/tede/5062.
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The Bico do Papagaio is an area of the State of Tocantins that is configured as a confluence zone with the states of Maranhão and Pará, forming an access channel, through Belém-Brasília, for people, goods and information of the Center-south to the North of the country. According to the Department of Development of the State of Tocantins (SEPLAN-TO), Bico do Papagaio is a political-administrative area composed by 25 municipal districts. The Ministry of the National Integration already understands that the area surpasses the borders of the State of Tocantins, by its North end and also that it goes to the Southwest of Maranhão and the Southeast of Pará. This last division is also assumed by the common sense, for the civil society and for politicians, what is justified historically for the bows built, because of its occupation process and geographical approaches, whose space, material and symbolically contiguous, is characterized by an important functional coherence. In this sense, our objective is to accomplish a study of the regional formation of Bico do Papagaio, considering the socioeconomic relationships that extrapolate the political-administrative limits of the official regionalization. This analysis perspective implicates in considering the functions of the urban and regional net and the population mobility. For so much, it inserts the study of the polarization in this analysis. Although the focus of this study is the regional formation, the established temporary cutting for this approach starts in 1988, year of the territorial division of the State of Goiás.
O Bico do Papagaio é uma região do Estado do Tocantins que se configura como uma zona de confluência com os estados do Maranhão e do Pará, formando um canal de acesso, via Belém-Brasília, para pessoas, mercadorias e informações do Centro-Sul ao Norte do país. Segundo a Secretaria de Desenvolvimento do Estado do Tocantins (SEPLAN-TO), o Bico do Papagaio é uma Microrregião político-administrativa composta por 25 municípios. Já o Ministério da Integração Nacional entende que essa região ultrapassa as fronteiras do Estado do Tocantins, em seu extremo Norte, e vai até o Sudoeste do Maranhão e o Sudeste do Pará. Este último recorte é também assumido pelo senso comum, pela sociedade civil e por políticos, o que se justifica pelos laços historicamente construídos, dado o seu processo de ocupação e as suas aproximações geográficas, cujo espaço, material e simbolicamente contíguos, caracteriza-se por uma importante coerência funcional. Neste sentido, o nosso objetivo é realizar um estudo da formação regional do Bico do Papagaio, considerando as relações sócio-econômicas que extrapolam os limites político-administrativos da regionalização oficial. Essa perspectiva de análise implica em considerar as funções da rede urbana e regional e a mobilidade populacional. Para tanto inserindo o estudo da polarização. Embora o foco desse estudo seja a formação regional, o recorte temporal estabelecido para esta abordagem se dá a partir de 1988, ano da divisão territorial do Estado de Goiás.
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Rendon, Piedrahita Camilo. "Study of highly conductive, flexible polymer electrolyte membranes and their novel flexoelectric effect." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1541440496157425.
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Zagdoun, Alexandre. "Dynamic Nuclear Polarisation Surface Enhanced NMR Spectroscopy." Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2014. http://tel.archives-ouvertes.fr/tel-01065554.
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Since its discovery in the 1950's, DNP has been a topic of significant interest in magnetic resonance. DNP is the transfer of polarization between single electrons and nuclei, driven by micro-wave irradiation. Since its renaissance at high field in the 90's, due to the introduction of gyrotrons as high-power, high-frequency microwave sources most application of this technique have been samples of biological interest in frozen solution. The long standing interest of our group in the characterization of surface species such as supported catalysts on silica lead us to apply this technique to the study of surfaces. The goal of this thesis is the development of this method, dubbed DNP Surface Enhanced NMR Spectroscopy. To that end, we first introduce new polarizing agents, soluble in organic solvents. The influence of the electron relaxation times on the DNP enhancements is demonstrated and efficient tailored polarizing agents are introduced. The optimization of the sample preparation to obtain optimal sensitivity is also discussed, as well as the interaction between the radical and the surface. These developments made it possible to apply the technique to many functionalized materials, with some examples developed in this manuscript. Finally, the issue of DNP on polarization conductors is discussed, and we show how microcrystals can be efficiently polarized using DNP.
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Barberena, Helfer Diego Eduardo. "Geometric phases in polarization mixed states." Master's thesis, Pontificia Universidad Católica del Perú, 2016. http://tesis.pucp.edu.pe/repositorio/handle/123456789/7053.
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Debido a la generalidad de su formulación, las fases geométricas han sido objeto de constantes investigaciones en áreas muy diversas y han llevado a muchos desarrollos, tanto en aplicaciones como en trabajo teórico. Esta tesis se incluye dentro de las investigaciones experimentales y se enfoca en las fases geométricas que aparecen al manipular el grado de libertad de polarización. Se divide en dos partes. La primera se centra en los aspectos teóricos esenciales que definen y relacionan los estados
mixtos de polarización con la luz láser parcialmente polarizada, y en las propiedades de las fases geométricas que aparecen en los primeros. La segunda parte presenta dos arreglos experimentales, uno que genera estados polarización y uno que permite medir la fase geométrica adquirida por dichos estados después de alguna evolución unitaria. El primero otorga un control casi arbitrario del estado de polarización de la luz láser que deja el arreglo y, con una ligera modificación, puede utilizarse en fotones individuales con casi idéntica efectividad. El segundo utiliza al primero para generar estados mixtos de polarización y luego los somete a distintas evoluciones.
Las fases geométricas adquiridas son entonces determinadas mediante su relación con las fases de Pancharatnam correspondientes, que son cantidades directamente observables. Si bien hubo casos en los que la fase no se pudo determinar debido a su sensibilidad a errores experimentales, en aquellas mediciones en las que se pudo obtener un valor experimental este se ajustó muy bien a la predicción teórica.Tesis
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Märker, Katharina. "Détermination structurale de systèmes organiques par polarisation dynamique nucléaire et RMN solide." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAV082/document.
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La détermination structurale supramoléculaire de solides organiques est d'une importance capitale pour la compréhension de leurs propriétés et de leur fonction. Des informations structurales à l’échelle atomique peuvent en principe être obtenues pour des composés en phase solide par la spectroscopie RMN (résonance magnétique nucléaire) combinée à la rotation de l’échantillon à l’angle magique (MAS). Cette technique est cependant confrontée à de fortes limitations de sensibilité, notamment en raison de la faible abondance isotopique naturelle (AN) d’isotopes clés, comme le carbone-13 et l’azote-15 (respectivement 1,1% et 0,37%).Une amplification de la sensibilité de plusieurs ordres de grandeur peut être obtenue avec la polarisation nucléaire dynamique (DNP), technique basée sur le transfert de polarisation des spins électroniques aux spins nucléaires. Les progrès récents dans la mise en œuvre pratique de la DNP ouvrent de nouvelles voies passionnantes, explorées dans cette thèse, pour la détermination de la structure des solides organiques.La première étape d’une étude structurale par RMN consiste en l'attribution spectrale des résonances. Malgré la faible AN des isotopes 13C et 15N, nous montrons dans ce travail que l’attribution complète de ces résonances pour un assemblage à base d’un dérivé de Guanosine est possible, grâce à l’utilisation d’expérience de corrélation multidimensionnelle 13C-13C et, pour la première fois, de spectre de corrélation 13C-15N.L'accent est alors mis sur l'obtention d'information structurale sous la forme de distances carbone-carbone et carbone-azote à partir d’expériences de transfert d’aimantation (expériences dites de « recouplage dipolaire »). Plusieurs stratégies sont discutées pour l’obtention de courbes de transfert d’aimantation sur des échantillons en AN. La dilution naturelle des isotopes 13C et 15N présente ici un avantage décisif pour ces mesures en réduisant de manière importante la troncature dipolaire, ce qui permet un transfert de polarisation sur de longues distances sans perturbation engendrée par la présence d’un troisième spin. Il en découle une description simplifiée de la dynamique de spin qui peut ainsi être facilement reproduite par des simulations numériques. Cette approche est démontrée expérimentalement sur des nanotubes du peptide diphénylalanine cyclique auto-assemblé (cyclo-FF). Les courbes de transfert d’aimantation 13C-13C et 13C-15N obtenues sont effectivement sensibles à de longues distances allant jusqu'à ~ 7 Å, et sont en excellent accord avec les simulations basées sur la structure cristalline du cyclo-FF. De plus, chaque courbe de transfert d’aimantation est constituée d’une superposition de contributions multiples intra et intermoléculaires, et contiennent donc une information structurale très riche.Il est ensuite montré que le contenu élevé de l'information contenu dans ces courbes de transfert d’aimantation et leur description théorique simple permettent de déterminer à la fois la structure moléculaire et la structure supramoléculaire du cyclo-FF. Ceci est réalisé à l'aide d'un code de calcul dédié qui crée de manière systématique des modèles structuraux par translation/rotation moléculaire et différentes symétries possible de la maille cristalline. Ces modèles sont ensuite classés en fonction de leur accord avec les données expérimentales.La thèse conclut en présentant des améliorations méthodologiques pour la séquence d'impulsions de recouplage dipolaire homonucléaire SR26. Cette séquence est particulièrement puissante pour une utilisation sur des échantillons en AN. Ces améliorations permettent une augmentation de l'efficacité du recouplage et l'acquisition de spectres de corrélation 2D avec de larges fenêtres spectrales.En résumé, cette thèse démontre que l'utilisation d'échantillons organiques en AN présente d’importants avantages pour leur étude structurale par RMN en phase solide qui devient possible avec la technique de DNP sous MASSupramolecular structure determination of organic solids is of utter importance for understanding their properties and function. Structural insights at the atomic level can be provided by magic-angle spinning (MAS) solid-state nuclear magnetic resonance (NMR) spectroscopy. However, this technique faces strong limitations in sensitivity due to the low natural isotopic abundance (NA) of the key nuclei 13C and 15N (1.1 % and 0.37 %, respectively). Sensitivity enhancement by several orders of magnitude can be achieved with dynamic nuclear polarization (DNP) which is based on polarization transfer from electron to nuclear spins. The recent progress in the practical implementation of DNP opens up new and exciting possibilities for structure determination of organic solids which are explored in this thesis.The first step for structural studies with NMR is resonance assignment. The complete assignment of 13C and 15N resonances at NA is demonstrated here to be feasible based on DNP-enhanced 13C-13C and, for the first time, 13C-15N correlation spectra.The focus is then laid on obtaining structural information in the form of carbon-carbon and carbon-nitrogen distances from the buildup of polarization in dipolar recoupling experiments. Several strategies are discussed for recording such polarization buildup curves at NA. A decisive advantage of these measurements is that dipolar truncation is reduced to a great extent in samples at NA, enabling undisturbed polarization transfer over long distances and a simple description of the spin dynamics by numerical simulations. This is demonstrated experimentally on the self-assembled cyclic diphenylalanine peptide (cyclo-FF). The 13C-13C and 13C-15N buildup curves obtained are indeed sensitive to long distances (up to ~ 7 Å) and are in excellent agreement with the crystal structure of cyclo-FF. Moreover, each buildup curve represents a superposition of multiple intra- and intermolecular distance contributions and can therefore provide a wealth of structural information.It is subsequently shown that the high information content and the simple theoretical description of such polarization buildup curves enables determination of both the molecular and the supramolecular structure of cyclo-FF. This is achieved with the help of a dedicated computational code which creates structural models based on a systematic grid-search and ranks them according to their agreement with the experimental data.The thesis concludes by presenting improvements for the homonuclear dipolar recoupling pulse sequence SR26 which is a powerful sequence for use in NA samples. These improvements enable increased recoupling efficiency and the acquisition of 2D correlation spectra with large spectral widths.Overall, this thesis demonstrates that clear advantages lie in the use of NA samples for structural studies of organic solids, and that MAS-DNP enables structure determination which is mainly based on distance information from NMR data
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Mishra, Rohan. "First Principles Study of Double Perovskites and Group III-V Compounds." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1345489862.
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Worth, Robert M. "Seeing Red: Immigration and Asymmetrical Partisan Polarization in the United States." ScholarWorks@UNO, 2018. https://scholarworks.uno.edu/td/2537.
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Since the mid-1970s, partisan polarization has been increasing in Congress and the Presidency, and, although most voters lack a stable, consistent ideology, non-ideological forms of partisan polarization have emerged in the mass public in recent decades. Moreover, ideological polarization among elites is highly asymmetrical, with increased Republican conservatism accounting for most of the increased ideological distance between the parties. Here, I develop a racial-threat backlash theory and argue that increased rates of immigration are associated with increased asymmetrical ideological polarization among elites and in the mass public. Tests of this theory on voters, the mass public in the states, state legislators, and Senators provide support for my theory. In addition, when accounting for the effects of immigration, I do not find support for the alternative explanation that increased income inequality leads to increased asymmetrical partisan polarization.
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BERECZKI, ALLAN. "Desenvolvimento de um laser DPSSL polarizado com mais de 100 W de potência e parâmetro de qualidade próximo de um." reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26822.
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A operação dinamicamente estável com zonas conjuntas foi obtida para um ressonador laser contendo dois bastões de Nd:YAG com módulos laser comerciais. O ressonador não polarizado gerou 115 W de potência no modo transversal fundamental TEM00. Quando polarizado por lâmina de Brewster atingiu 100,5W de potência de saída com 91% de polarização. Quando o ressonador foi polarizado com um polarizador de filme fino, obteve-se melhora na qualidade de feixe e um aumento na polarização, com o valor de M2 sendo 1,56 e 1,84 nas direções x e y respectivamente com 95,4% de polarização. A potência de saída foi, ao nosso conhecimento, a mais alta obtida para lasers polarizados operando no modo fundamental e usando módulos lasers comerciais de Nd:YAG bombeados lateralmente por diodos sem nenhuma preparação especial.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Norton, Mike. "Papers on the polarization of Congress." Thesis, University of Oxford, 2018. http://ora.ox.ac.uk/objects/uuid:5ce87b5b-2d2f-403e-b2d4-85f23b2a14cc.
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This dissertation, a collection of independent papers, explores the polarization of the United States Congress through the lens of primary elections, campaign finance, and party structures during a pivotal moment in American political history. Paper 1 focuses on the top two primary format and its potential in producing moderate candidates and legislators, while Paper 2 expounds on the deleterious consequences it poses for the party system as a whole, particularly in this modern era of both high polarization and high fragmentation. Paper 3 examines the Downsian median voter theorem from the perspective of primary election voters, asking if general election wins/losses beget the nomination of more ideological/moderate nominees next cycle. Ultimately, the article illustrates that the parties instead retain consistent records through both election wins and losses, linked to credibility concerns from position changes as well as the inability of members to disentangle from national party identities. Its companion paper, Paper 4, takes that Downsian question to elites in Washington, D.C. Through original interviews with twenty-three individuals including former members of Congress, leadership, congressional staff, and think tank scholars, I describe the electoral and legislative pressures that prevent officeholders from responding to their median voter, especially among those in swing districts most exposed to the risks of partisan behavior. Paper 5, the final paper, brings together the themes of those preceding it by analyzing the ways in which outside interference, specifically political action committees and more inclusive primary elections, propagates legislative caucus fragmentation and weakens official leadership. This work plays one minor role in providing prescriptive steps to improve and empower channels of dialogue in the U.S. legislative brancha - in spite of larger systemic sorting along geographical and partisan lines - and ensure the mediation of ideology between voters and their elected representatives results in policy solutions rather than gridlock.
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Campbell, Colin S. "Dead Center: Polarization and the Democratic Party, 1932-2000." Digital Commons @ East Tennessee State University, 2016. https://dc.etsu.edu/etd/3117.
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Polarization forced massive changes in the institutions of Washington throughout the 20th century, and the Democratic Party played a key role throughout. Under President Franklin D. Roosevelt, the Democratic Party formed the powerful New Deal coalition. The coalition faltered in the turbulent 1960s under the pressures of the Vietnam War and racial unrest. The chaotic 1968 Democratic National Convention in Chicago dealt the coalition a mortal wound. Young voters and activists gained an outsized voice in the party. Several crushing defeats in presidential elections followed as the party chose unelectable candidates who appealed to the passions of left-wing activists and interests. In 1992, Bill Clinton won the nomination and forced the party back to the center. Clinton’s success, however, drove the Republican Party further right as its efforts to destroy Clinton grew increasingly obsessive. The cumulative effect has been an increase in polarization and the weakening of institutions in Washington.
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Bai, Jianmei. "Collisional Molecular Orientation Transfer Facilitated Polarization Spectra of the A/b States of the Rb2 and Cs2 Dimers." Diss., Temple University Libraries, 2011. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/155795.
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PhysicsPh.D.
The focus of this thesis is the study of the strongly perturbed A/B complex of electronic states of the Rb2 and Cs2 dimers. Using collisional molecular orientation transfer facilitated high resolution V- type optical-optical double-resonance (OODR) polarization spectroscopy, it was possible to observe a much larger number of rovibrational levels in the A/B complex of states than anticipated. In addition to the direct P, R doublets, we have observed probe laser signals from a large number of collisionally populated rotational levels. Angular momentum changes up to delta J = 58 were observed in the recorded 85 Rb2 spectra. Observation of these satellite lines is based on transfer of both population and orientation from the rovibrational levels involved in the pump laser excitation to neighboring levels in a collision of the molecule with atomic perturbers. The Discrete variable representation (DVR) method was used to analyze this data combined with other available data in a global deperturbation analysis of the spin-orbit interaction of the strongly perturbed A/B complex of Rb2 and Cs2 electronic states. The resulting experimentally derived potential energy curves and internuclear distance dependent spin-orbit functions are presented in H. Salami et al., Phys. Rev. A80, 022515 (2009) and Jianmei Bai et al., Phys. Rev. A83, 032514 (2011). In addition, the analysis yields the term values of the rovibrational energy levels and their percentage of singlet and triplet character.
Temple University--Theses
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Honda, S., H. Itoh, J. Inoue, H. Kurebayashi, T. Trypiniotis, C. H. W. Barnes, A. Hirohata, and J. A. C. Bland. "Spin polarization control through resonant states in an Fe/GaAs Schottky barrier." American Physical Society, 2008. http://hdl.handle.net/2237/11246.
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Abazov, V. M., B. Abbott, B. S. Acharya, M. Adams, T. Adams, J. P. Agnew, G. D. Alexeev, et al. "Measurement of top quark polarization in t ¯ t lepton + jets final states." AMER PHYSICAL SOC, 2017. http://hdl.handle.net/10150/622747.
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We present a measurement of top quark polarization in t (t) over bar pair production in p (p) over bar collisions at root s = 1.96 TeV using data corresponding to 9.7 fb(-1) of integrated luminosity recorded with the D0 detector at the Fermilab Tevatron Collider. We consider final states containing a lepton and at least three jets. The polarization is measured through the distribution of lepton angles along three axes: the beam axis, the helicity axis, and the transverse axis normal to the t (t) over bar production plane. This is the first measurement of top quark polarization at the Tevatron using lepton + jet final states and the first measurement of the transverse polarization in t (t) over bar production. The observed distributions are consistent with standard model predictions of nearly no polarization.
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Meyer, Alix. "Le Congrès républicain (1994 – 2006)- Révolutions conservatrices, contradictions électorales, évolutions institutionnelles." Thesis, Lyon 2, 2012. http://www.theses.fr/2012LYO20083.
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Le Congrès des Etats-Unis est une institution méconnue, mal comprise et souvent dénigrée, y compris par ses propres membres. On le dit en crise, inadapté aux exigences du monde moderne. L’objectif est donc d’évaluer les forces et les faiblesses objectives du Congrès contemporain pour le réinsérer dans la dynamique des freins et contre-pouvoirs au coeur du système politique américain. La période retenue s’étale de la victoire des Républicains menés par Newt Gingrich en 1994 jusqu’aux élections de mi-mandat de 2006 et au retour des Démocrates. De la présidence Clinton à Bush, ces douze années offrent un contexte institutionnel varié. Elles forment une trajectoire historique fascinante de la rhétorique révolutionnaire qui accompagne les victoires de 1994 à la résignation d’une défaite marquée par une certaine corruption institutionnelle, partisane et idéologique. Le cœur de notre étude vise à étudier les conséquences institutionnelles du retour à un équilibre partisan dans les deux chambres du Congrès. La compétition entre les deux partis a été accompagnée par la polarisation du système politique. Notre étude retrace les débuts de l’entrée dans une nouvelle ère sur la colline du Capitole. On cherchera à combiner une approche politique et institutionnelle en analysant plus particulièrement trois domaines de l’action politique particulièrement révélateurs: les finances via la procédure budgétaire, la réforme de l’Etat providence, et les relations avec le judiciaire via les nominations des Juges d’Appel fédéraux, lieu privilégié de frictions entre la Maison-Blanche et le Sénat. À cette perspective institutionnelle, il s’agira d’ajouter une étude sociologique de cohorte des membres du Congrès, nécessaire pour comprendre les ressorts de l’action institutionnelle. Au-delà des membres de la chambre, l’étude d’une période dominée par le parti de l’éléphant nous permettra de plonger au cœur du mouvement conservateur. Après avoir présenté les racines historiques de l'idéologie conservatrice qui domine au sein du Parti républicain, il s'agira de révéler comment un mouvement contestataire a transformé l’institution du Congrès mais aussi comment l’institution a transformé le mouvement conservateur et le Parti républicain. Dans un contexte international de renforcement du pouvoir exécutif, l’étude du Congrès doit permettre de redécouvrir certaines leçons sur les modalités de fonctionnement d’un système démocratique. Il s’agit de montrer qu'au-delà des questions techniques, des jeux de procédures obscures, dans la tension qui anime le Congrès, se joue l’avenir du concept de démocratie représentative ; de rétablir un certain équilibre dans la perception du système américain : système plus complexe qu’il n’apparaît dans les médias et même parfois la littérature. On ne peut se contenter d’étudier la présidence impériale sans prêter attention au vortex qui siège, toujours, au coeur de la constitution. Ainsi, sans faire un panégyrique du pouvoir législatif, il s’agira de remettre en cause la tentation d’un Césarisme plus ou moins démocratique qui chercherait à faire du Congrès une chambre d’enregistrement des volontés de l’exécutifThe United States Congress is often disparaged including by its own members. The critics of the institution decry the gridlock on Capitol Hill and Congress's alleged inability to deal with the challenges of the modern world. The unpopularity of today's Congress calls into question its ability to represent the American people. In that context it is necessary to try to assess whether or not Congress is truly dysfunctional. To that end, this study proposes to study a period of twelve years from 1994 to 2006 during which the Republican party dominated the institution. In 1994, under the leadership of Newt Gingrich, the Republicans returned to the majority in the House of Representatives for the first time in forty years. In 2006, after another midterm election, the Republican majorities in the House and the Senate were soundly defeated. Drawing on the long and tortuous history of the relationship between the Republican party and conservatism, the new majorities proposed large-scale change that amounted to a conservative revolution. They had initially laid out a clearly conservative agenda that insisted on balancing the budget and reducing the size of government. A detailed study of their fiscal policy and their attempts at entitlement reform over the period actually leads us to conclude that they eventually governed over ever larger deficits and a growing federal government whose policies were adjusted to favor different portions of the population. It is therefore necessary to try to account for the discrepancy between the initial goals and the eventual results. This entails studying first the evolution of the Republican members of Congress themselves to see whether the policy changes can be explained by the members becoming more moderate. Another explanation centers on the relationship between the members of the Congress and their constituents. The Republican majorities could have been forced to moderate their positions by the voters themselves in the elections of 1996, 1998, 2000, 2002 and 2004. Here the complex interplay that implies the interpretation of election results comes into play. Over the past decades, the American political system has been polarizing clearly. The growing ideological gap between the two parties and their bases calls into question the institutional stability of an institution built on the necessity to compromise. Especially since both parties have polarized while the margins of the majorities have grown more narrow. It is thus essential to look at the constraints set up by the institutional system. The arcane nuances of the legislative process directly impinges on the content of legislation. Indeed, if the majority rules decisively over the House of Representatives, in the Senate, the minority can very easily block most initiatives. The growing recourse to procedural shortcuts offered by the budget process is a testament to that fact.Finally, the relationship with the president of the United States is very much a factor in the equation. The twelve years of Republican domination in Congress covers two very different periods. Until January 2001, they had to battle with President Clinton in a context of divided government. Following George W. Bush's election in 2000, they started working under the command of the White House. The stark contrast in the way Senate republicans dealt with the two presidents when it came to their judicial nominees for the Federal Courts of Appeal offers an excellent opportunity to evaluate the continuing yet variable strength of the system of checks and balances set up by the U.S. Constitution. A deeper understanding of the workings of the contemporary Congress might allow for a more nuanced vision of the institution as much more than a roadblock on the road of presidential leadership and, perhaps, lead to a better appreciation of the way its members are trying or failing to fulfill their constitutional duty
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Day, Iain J. "Real-time NMR of the transient states of proteins." Thesis, University of Oxford, 2004. http://ora.ox.ac.uk/objects/uuid:19b0637b-e28a-4d34-9016-ebfb5a507720.
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The work described in this thesis is concerned with the development and application of real-time photo-CIDNP (Chemically Induced Dynamic Nuclear Polarisation) to the study of protein structure and folding. Chapters 1 and 2 introduce the protein folding problem, and its study by NMR, then go on to elucidate the mechanisms behind the photo-CIDNP phenomenon. Chapter 3 applies photo-CIDNP spectroscopy to the study of a small cytochrome protein. The difficulties of performing these experiments on chromophore-containing proteins are discussed. Chapter 4 begins with the development of a rapid mixing device for use in real-time NMR and CIDNP studies. Experiments used to characterise the device are presented. This chapter then goes on to describe CIDNP pulse labelling experiments, used to investigate the surface structure of some molten globule states of two a-lactalbumins. This chapter concludes with an application of the rapid mixing device to the real-time refolding of hen egg white lysozyme. Chapter 5 extends the work of the previous chapter, studying the real-time refolding of bovine pancreatic ribonuclease A. Refolding studies are performed from different denaturing conditions, and the effects of sample heating during the real-time CIDNP experiment are discussed. Chapter 6 describes the use of illumination during an NMR experiment to study the conformational changes in a plant blue light receptor protein, phototropin. The structural changes are characterised with 2-dimensional NMR spectroscopy and photo-CIDNP. The kinetics of the ground state recovery are also investigated by real-time NMR spectroscopy. Chapter 7 uses calculated hyperfine coupling constants and a radical pair diffusion model from the literature to simulate the nuclear polarisation obtained for the amino acid tryptophan. Comparisons are made between theory and experiment. Chapter 8 describes the structural characterisation of a homologous series of de novo peptides, designed for subsequent use in EPR experiments when derivatised with a suitable spin label.
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Dalgliesh, William Robert. "A theoretical and experimental study of the polarization states of a Nd³§+:YAG laser." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0027/NQ35138.pdf.
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