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1
Gagnon, Justin. "Omnidirectional Phase Matching In Zero-Index Media." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42029.
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Since its inception, the field of nonlinear optics has only increased in importance as a result of a growing number of applications. The efficiency of all parametric nonlinear optical processes is limited by challenges associated with phase-matching requirements. To address this constraint, a variety of approaches, such as quasi-phase-matching, birefringent phase matching, and higher-order-mode phase matching have historically been used to phase-match interactions. However, the methods demonstrated to date suffer from the inconvenience of only being phase-matched for one specific arrangement of beams, typically co-propagating along the same axis. This stringency of the phase-matching requirement results in cumbersome optical configurations and large footprints for integrated devices. In this thesis, we show that phase-matching requirements in parametric nonlinear optical processes may be satisfied for all orientations of input and output beams when using zero-index media: a condition of omnidirectional phase matching. To validate this theory, we perform experimental demonstrations of phase matching for five separate FWM beam configurations to confirm this phenomenon. Our measurements constitute the first experimental observation of the simultaneous generation of a forward- and backward-propagating signal with respect to the pump beams in a medium longer than a free-space optical wavelength, allowing us to determine the coherence length of our four-wave-mixing process. Our demonstration includes nonlinear signal generation from spectrally distinct counter-propagating pump and probe beams, as well as the excitation of a parametric process with the probe beam's wave vector orthogonal to the wave vector of the pump beam. By sampling all of these beam configurations, our results explicitly demonstrate that the unique properties of zero-index media relax traditional phase-matching constraints, and provide strong experimental evidence for the existence of omnidirectional phase matching in zero-index media. This property can be exploited to facilitate nonlinear interactions and miniaturize nonlinear devices, and adds to the established exceptional properties of low-index materials.
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Nazare, Julie-Anne. "Modulation de la phase postprandiale du glucose." Phd thesis, Université Claude Bernard - Lyon I, 2009. http://tel.archives-ouvertes.fr/tel-00878436.
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La réduction des excursions glycémiques postprandiales a été proposée comme un moyen pour limiter le risque de développement du diabète de type 2. L'intérêt s'est donc porté sur les outils nutritionnels susceptibles de moduler la biodisponibilité des glucides et ainsi leur impact sur la glycémie postprandiale. Les travaux réalisés au cours de cette thèse avaient pour but d'étudier les effets de différents ingrédients modifiant la biodisponibilité du glucose, non seulement sur la glycémie postprandiale à court terme (2 heures) mais aussi sur les cinétiques du débit d'apparition et de disparition de glucose (total, exogène et endogène - isotopes stables) et les autres paramètres métaboliques de la phase postprandiale au cours de la journée. Dans la première étude (β-glucanes), nous avons montré que l'addition de fibres β-glucanes à un repas glucidique chez des sujets sains en surpoids ralentit l'absorption du glucose dans le plasma. Ceci a prolongé la réponse insulinique et par conséquent l'inhibition de la lipolyse et de la production endogène de glucose. Dans la deuxième étude (Eurostarch), nous avons montré que la diminution de la biodisponibilité du glucose au petit-déjeuner (amidon lentement digestible, index glycémique bas) diminue l'apparition du glucose exogène dans le plasma et pourrait avoir un effet second-repas chez des sujets sains en surpoids. Mais nous n'avons pas mis en évidence d'amélioration de ces effets métaboliques à plus long terme (5 semaines). Dans la troisième étude présentée (Nutriose), nous avons montré que l'addition de dextrine résistante NUTRIOSE®10 (fermentescible) au petit-déjeuner chez des sujets sains, diminue les réponses glycémiques, insuliniques postprandiales et le profil de ghréline au cours de la journée (en comparaison à une maltodextrine). En parallèle, la prolongation observée de la fermentation et l'oxydation du NUTRIOSE®10 pourraient fournir de l'énergie en phase postprandiale tardive. En conclusion, l'analyse des paramètres métaboliques au-delà de 2 heures après le repas, a permis de mettre en évidence les effets métaboliques à plus long terme de la modulation de l'apparition du glucose dans le plasma (ralentissement, prolongation, réduction) sur les cinétiques du glucose, la réponse insulinique, la lipolyse et l'oxydation des substrats
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Luciani, Riccardo. "Study of Europe-ENSO teleconnection in an El Niño index phase analysis framework." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18807/.
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El Niño/Southern Oscillation (ENSO) is the most important coupled ocean-atmosphere phenomenon to cause global climate variability on seasonal to interannual time scales. Therefore understanding some of its most important features may help to shed light on the field of climate predictions. Here the focus is put on the seasonal precipitation patterns which respond to persistent thermal forcing happening thousands of kilometers far away.
The first objective of this work is to look for and describe the correlation patterns between seasonal rainfall anomalies over Northern Italy and global seasonal Sea Surface Temperature anomalies (SSTA). Tri-monthly means of precipitation and tri-monthly means of SSTA from observational datasets are used in an anomaly correlation study in order to explore this teleconnection. The study is developed in the Nino Index Phase Analysis (NIPA) framework, as presented by Zimmerman et al., which consists in separating the positive and negative ENSO phase years in the computation of the anomaly correlation.
The second objective of the work is to check if the correlations found are consistent with the shift of the circulation pattern which is due to a non-weak ENSO state. The anomaly means of the main ocean-atmospheric variables are examined in order to characterise the way in which the circulation works when the system is under El Niño or La Niña conditions and when the precipitation over the basins is higher or lower.
Then, a Rossby waves simulation software is used to show that the propagation of a Rossby wave train, in a basic state with zonally varying middle latitude or low latitude jet, may be the cause of the correlations in the area under exam and for the seasons chosen, and how. This is an indication of the fact that the ENSO state and its spatial features can influence the tropospheric pathways through which planetary waves can propagate and this, in turn, could have an effect on midlatitudes large-scale circulation.
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Hammond, Troy Douglas. "Atom interferometry--dispersive index of refraction and rotation induced phase shifts for matter-waves." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/46044.
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Okman, Osman Erman. "Quantization Index Modulation Based Watermarking Using Digital Holography." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607506/index.pdf.
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The multimedia watermarking techniques are evolved very quickly in the last years with the increase in the use of internet. The evolution of the internet makes the copyright issues very important and many different approaches are appeared to protect the digital content. On the other hand, holography is the method to store the 3-D information of an object but it is very applicable to use as a watermark because of the nature of the holographic data. The 3-D object can be reconstructed from the hologram even if the hologram is cropped or occluded. However, watermarking of an image with a hologram is a very novel approach and there are only a few works in the literature which are not very robust against the attacks like filtering or compression. In this thesis, we propose to embed the phase of the hologram to an image using quantization index modulation (QIM). QIM is utilized to make the watermarking scheme blind and degrade the host image as low as possible. The robustness of the proposed technique is also tested against several attacks such as filtering, compression, etc. The evaluated performance of this system is compared with the existing methods in the literature which uses either holograms or logos as the secret mark. Furthermore, the characteristics of the holograms are investigated and the findings about the hologram compression are reported in this work.
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Whitfield, Erica Marie. "Propagation of Gaussian Beams Through a Modified von Karman Phase Screen." University of Dayton / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1355513250.
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Salcedo, Luis E. "The Proto-Lauricocha Phase Of The Central Andes And The Origin Of Andean Foliated Point Tradition." Pontificia Universidad Católica del Perú, 2014. http://repositorio.pucp.edu.pe/index/handle/123456789/113582.
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This paper discusses early evidence for the Andean Foliated Point Tradition (TAPF in Spanish), with special emphasis on theCentral Andes region and the Lauricocha complex, which are included into the so-called ‘Proto-Lauricocha’ phase (Salcedo 2006).This phase is characterized by the indiscriminate consumption of animal species prior to food production, and the presence of foliated projectile points featuring centripetal retouch and minute ailerons located at one-third of the maximum longitude of thepiece, defi ning in that way a pseudo-peduncle. The cultural phase has been dated by the radiocarbon method in the 10,500-7400 years cal BC interval, employing the dendrochronological calibration with the support of the OxCal v3.10r program (Bronk-Ramsey 2005) and the current calibration curves (Reimer et al. 2004; Reimer et al. 2009). Comparative evidence found in North America and Japan is used to discuss the probable origin of TAPF.El presente artículo discute las evidencias más tempranas correspondientes a la Tradición Andina de Puntas Foliáceas (TAPF), con especial énfasis en los hallazgos realizados en los Andes Centrales, adscritos al complejo Lauricocha, los que son incluidos dentro de la denominada fase Proto-Lauricocha (Salcedo 2006), la que se caracteriza por un consumo indiscriminado de especies animales, previo a la producción de alimentos y la presencia de puntas de proyectil foliáceas de retoque centrípeto, con diminutos alerones ubicadosa un tercio del largo máximo de la pieza, con lo que se definió un pseudopedúnculo. Esta fase cultural ha sido fechada por el método de radiocarbono en el intervalo 10.500-7400 cal AC por medio del empleo de la calibración dendrocronológica con ayuda delprograma OxCal v3.10r (Bronk-Ramsey 2005) y las curvas de calibración vigentes (Reimer et al. 2004; Reimer et al. 2009). Asimismo, se rastrea el probable origen de la TAPF en virtud a las evidencias similares halladas en Norteamérica y Japón.
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Thompson, Jonathan R. "Dynamics of Singlet Excitons in Alq3 and Magnetic Mode Switching in Index Matched Organic Waveguides." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535459125887475.
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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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Geday, Morten A. "Birefringence imaging." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365446.
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Peiponen, K. E. (Kai-Erik). "Optical spectra analysis of turbid liquids." Doctoral thesis, University of Oulu, 2009. http://urn.fi/urn:isbn:9789514291685.
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This thesis is devoted to methods of analyzing optical spectra obtained from turbid liquids, i.e., liquids that are optically very thick and/or scatter light. Data for spectral analysis were obtained with a new, multifunction spectrophotometer developed for industrial liquid samples. One characteristic of the spectrophotometer is that spectral analysis methods can be implemented into the software. Here, the emphasis was on data inversion methods, particularly the Kramers-Kronig analysis and the maximum entropy method, which can be used to gain information on the wavelength-dependent complex refractive index of liquid samples. Relating to such characteristics as density and colour, the complex refractive index also helps to identify the species that form a liquid. The methods were applied to study the internal reflection of light from the prism-liquid interface of the probe and to analyze surface plasmon resonance spectra. This study provided new methods of investigating the optical properties of relatively difficult objects, like offset inks, and of assessing adhesion forces between ink and the substrate system. Another important part of the thesis was the exploration of spectral analysis methods to obtain optical properties of nanoparticles in a liquid matrix. Bounds for the optical properties of multi-component structures in a liquid were considered with the aid of Wiener bounds.
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Keeling, David. "Novel thin film optical modulator/tunable retarder." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/29595.
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Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2007.Committee Chair: A. Rahman Zaghloul ; Committee Members: W. Russell Callen and Doug Yoder. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Ben, Harush Negari Amit. "Tapered Optical Fiber Platform for High Sensitivity Refractive Index Sensing Applications." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1417644120.
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Ravash, Roghaiyeh [Verfasser], and Armin [Akademischer Betreuer] Dadgar. "Growth of semi-polar GaN on high index silicon (11h) substrates by metal organic vapor phase epitaxy / Roghaiyeh Ravash. Betreuer: Armin Dadgar." Magdeburg : Universitätsbibliothek, 2014. http://d-nb.info/1054638365/34.
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Onuki, Yoshio. "El Periodo Arcaico en Huánuco y el concepto del Arcaico." Pontificia Universidad Católica del Perú, 2012. http://repositorio.pucp.edu.pe/index/handle/123456789/113560.
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The Archaic Period in Huánuco and the Concept of ArchaicThe Archaic Period in the Central Andes can be considered as the period of postglacial adaptation and, in this sense, the necessity of comparative studies with similar processes in other parts of the world like Europe, Near East, or the Jomon Period in Japan should be revised. Not only for this purpose but also for Andean studies proper, it is necessary to proceed more sistematic excavations of the Archaic Period in Peru. The present article offers an interpretation of the socioreligious aspect of the Archaic Period or Initial Formative Period in the upper Huallaga basin in order to reconsider the concept of Archaic and reorganize a new chronological scheme for the Formative Period.El Periodo Arcaico en los Andes Centrales es el periodo de la adaptación postglacial y en ese sentido es necesario profundizar en el estudio comparativo con Europa, Cercano Oriente o el Periodo Jomon en el Japón. Se tiene la necesidad, por lo tanto, de realizar sistemáticamente más excavaciones y análisis de los materiales y los datos. El presente artículo trata del aspecto socioreligioso de la fase Kotosh-Mito en el valle alto del Huallaga y presenta una idea del concepto del Arcaico y de la redefinición del Formativo con un nuevo esquema cronológico.
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Wang, Mei. "Chromatography with no stationary phase /." Full text available from ProQuest UM Digital Dissertations, 2006. http://0-proquest.umi.com.umiss.lib.olemiss.edu/pqdweb?index=5&did=1383464751&SrchMode=1&sid=4&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1217274375&clientId=22256.
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Watanabe, Shinya. "El reino de Cuismancu: orígenes y transformación en el Tawantinsuyu." Pontificia Universidad Católica del Perú, 2012. http://repositorio.pucp.edu.pe/index/handle/123456789/113385.
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The Cuismanco Kingdom: Origins and Transformation in the TawantinsuyuThis paper presents the data of excavation data from Tantarica site, in the northern highland of Peru, also examines the extent interpretations about the Cuismancu Kingdom based on the documents. Up to now the opinion prevents that the Cuismancu Kingdom existed before the arrival of the Incas and was incorporated into the Inca dominion. This interpretation contradicts the archaeological data. The material culture of Tantarica is closer to the north coast than with the Cajamarca Basin, which indicates heterogeneity within the domain of the Cuismancu Kingdom. Thus, it is probable that the political unit as seven warangas of the Cuismancu Kingdom was formed under the Inca domain and is not of preincaic origin.En este artículo se presentan los resultados de excavaciones llevadas a cabo en el sitio arqueológico de Tantarica, ubicado en la sierra norte del Perú, y se revisa interpretaciones sobre el reino de Cuismancu sobre la base de los documentos. Hasta la fecha se mantiene la imagen de un reino de Cuismancu que existió antes de la llegada de los incas y que se incorporó bajo su dominio. Sin embargo, esta interpretación no concuerda con los datos arqueológicos. Los materiales arqueológicos de Tantarica presentan una relación más estrecha con la costa norte que con el valle de Cajamarca, indicando que existe más bien una heterogeneidad dentro de dicho reino. Por ello, es razonable pensar que la unidad política del reino de Cuismancu en forma de siete warangas se formó bajo el dominio incaico y que no se remonta al periodo inmediatamente anterior.
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Ek, Simon. "Distributed Temperature Sensing Using Phase-Sensitive Optical Time Domain Reflectometry." Thesis, KTH, Tillämpad fysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-285902.
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This thesis explores and evaluates the temperature measuring capabilities of a phase-sensitive optical time-domain reflectometer (φ-OTDR), which exploits Rayleigh backscattering in normal single mode optical fibers. The device is constructed and its setup explained, and a protocol for making temperature measurements with it is developed. Performance tests are made and the device is shown to achieve fully distributed temperature measurements on fibers hundreds of meters in length with a spatial resolution of 1 m and a temperature resolution of 0.1 K. In addition, the capabilities of the device to measure normal strain in the measurement fiber are tested using the same approach, albeit with less success. The device is capable of very precise measurements, making it very sensitive to the environmental conditions around the measuring fiber but also susceptible to disturbances. Some discussion is had on how to avoid or deal with these disturbances. Furthermore, the technique is shown to be able to run in conjunction with other φ-OTDR measurement techniques from the same device simultaneously.Det här examensarbetet utforskar och utvärderar förmågorna att mäta temperatur hos en fas-känslig optisk tidsdomän-reflektometer (φ-OTDR), som utnyttjar bakåtriktad Rayleigh-spridning i vanliga optiska singelmodfibrer. Anordningen konstrueras och dess komponentstruktur förklaras, och ett protokoll tas fram för att utföra mätningar med den. Prestandatester utförs och anordningen visas kapabel att göra fullt distribuerade temperaturmätningar längs hundratals meter långa fibrer, med en rymdsupplösning på 1 m och en temperaturupplösning på 0.1 K. Dessutom testas förmågan att mäta normaltöjning hos testfibern med samma metod, dock med mindre framgång. Anordningen är väldigt känslig för förhållandena i omgivningen runt mätningsfibern, vilket gör den kapabel till mätningar med mycket hög precision, men också mottaglig för störningar. Lite diskussion hålls kring hur dessa störningar kan undvikas eller hanteras. Vidare visas att mätningstekniken kan köras samtidigt som andra φ-OTDR-baserade tekniker från samma anordning.
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Müller, Paul. "Optical Diffraction Tomography for Single Cells." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-202261.
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Analyzing the structure of a single cell based on its refractive index (RI) distribution is a common and valued approach, because it does not require any artificial markers. The RI is an inherent structural marker that can be quantified in three dimensions with optical diffraction tomography (ODT), an inverse scattering technique. This work reviews the theory of ODT and its implementation with an emphasis on single-cell analysis, identifying the Rytov approximation as the most efficient descriptor for light propagation. The accuracy of the reconstruction method is verified with in silico data and imaging artifacts associated with the inverse scattering approach are addressed. Furthermore, an experimental ODT setup is presented that consists of a bright-field microscope, a phase-imaging camera, and an optical trap combined with a microfluidic chip. A novel image analysis pipeline is proposed that addresses image corrections and frame alignment of the recorded data prior to the RI reconstruction. In addition, for a rotational axis that is tilted with respect to the image plane, an improved reconstruction algorithm is introduced and applied to single, suspended cells in vitro, achieving sub-cellular resolution.
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Maggard, Greg J. "Late Pleistocene-Early Holocene Occupations of the North Coast Of Perú." Pontificia Universidad Católica del Perú, 2014. http://repositorio.pucp.edu.pe/index/handle/123456789/113377.
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On Perú’s North Coast, the earliest documented lithic traditions are collectively known as the El Palto Phase (~14,200-9600cal BP). This phase, which spans the Late Pleistocene to Early Holocene, contains evidence for several contemporary or overlapping traditions, including early unifacial assemblages, and the Fishtail and Paiján complexes. Recent study of El Palto phasesites in the lower Jequetepeque Valley focused on evaluating the relationships between these assemblages and the populations who manufactured them. The results of this study indicate a greater degree of intratype diversity among point types than previously recognized and call into question the descendant relationships between Fishtail and Paiján. The results from several long-term regional studies are combined with these analyses to provide new insight regarding early settlement and technological change in this region of the Central Andes.En la costa norte del Perú, las tradiciones líticas más tempranas documentadas se conocen, en conjunto, como la fase El Palto (~14.200-9600 cal AP). Esta fase, que abarca desde el Pleistoceno Final hasta el Holoceno Temprano, contiene evidencias de varias tradiciones contemporáneas o que coinciden parcialmente en el tiempo, lo que incluye conjuntos unifaciales tempranos y los complejos Cola de Pescado y Paiján. Un reciente estudio de los sitios de la fase El Palto en el valle bajo de Jequetepeque se enfocó enla evaluación de los vínculos entre estos conjuntos y las poblaciones que los produjeron. Los resultados obtenidos indican un grado mayor de diversidad tipológica entre los tipos de puntas que lo que previamente se había reconocido y cuestionan las relaciones tecnológicas entre las tradiciones líticas Paiján y Cola de Pescado. Asimismo, los resultados de varios estudios regionales de largoplazo se combinan con estos análisis con el objeto de proporcionar una nueva comprensión acerca del asentamiento temprano y el cambio tecnológico en esta región de los Andes Centrales.
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Beresford-Jones, David, Carmela Alarcón, Susana Arce, Alex Chepstow-Lusty, Oliver Whaley, Fraser Sturt, Manuel Gorriti, Oscar Portocarrero, and Lauren Cadwallader. "Early Horizon Occupation and Subsistence in the Context of Long-Term Ecological Changes in the Samaca and Ullujaya Basins, Lower Ica Valley." Pontificia Universidad Católica del Perú, 2012. http://repositorio.pucp.edu.pe/index/handle/123456789/113626.
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This paper presents the results of archaeobotanical and malacological analyses of a midden dating to Ocucaje Phases 3 to 4 (c. 750 BC) in secure stratigraphic association beneath the contexts of an Early Nasca canal fragment in the Ullujaya Basin in the lower Ica Valley, on the south coast of Perú. Such preservation of early occupation contexts is otherwise rare within the landscape of the Lower Ica Valley, the topography of much of which is determined today by the long effects of wind erosion upon its once extant stratigraphy. These ancient rubbish remains contain no domesticated plant remains other than cotton, but only sea urchin debris and other marine and terrestrial mollusc resources gathered from the lomas and Pacific Ocean some 25 kilometres distant. They do contain some plant remains, including gathered wild foods such as huarango beans, and other plants typical of riparian woodland. We present these results in the context of other data from the Samaca and Ullujaya Basins, including the remains of middens from later time periods and a pollen sequence, to argue that, together, they show a steady intensification of agriculture in these basins during the subsequent Early Intermediate, but which culminates ultimately in a collapse of agricultural production here and a return to the gathering of wild marine and plant resources much later, during the Middle Horizon.Este artículo presenta los resultados de análisis arqueobotánicos y malacológicos realizados en los materiales de un basural fechado hacia las fases Ocucaje 3 a 4 (c. 750 a.C.), con asociación estratigráfica segura debajo de los contextos de una sección de canal del Periodo Nasca Temprano en la cuenca de Ullujaya, en el valle bajo de Ica, costa sur del Perú. Semejante conservación de contextos de ocupación tempranos es poco común al interior del paisaje de esta zona, cuya topografía está determinada, en la actualidad, por los prolongados efectos de la erosión eólica sobre la que tenía en el pasado. Estos antiguos restos de basura no contienen vestigios de plantas domesticadas, con excepción del algodón, además de restos de erizos de mar y otros recursos en forma de mariscos marinos y terrestres recolectados de las lomas y el océano Pacífico, distante 25 kilómetros. Sin embargo, sí contienen algunos restos de plantas, entre las que están alimentos silvestres como semillas de huarango y otras plantas típicas de bosques ripícolas. Se presentan estos resultados en el contexto de otros datos procedentes de las cuencas de Samaca y Ullujaya —como, por ejemplo, los restos de basurales de épocas posteriores y una secuencia palinológica— con el objeto de mostrar, en conjunto, la sostenida intensificación de la agricultura en estas zonas durante el subsiguiente Periodo Intermedio Temprano, lo que desembocó en el colapso de la producción agrícola y el retorno a la recolección de recursos marinos y vegetales durante el Horizonte Medio.
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Bardales, Castro Percy. "¿Es posible la admisión de medios probatorios y/o argumentos luego del cierre de los requerimientos? Breves notas con motivo de la aplicación del reglamento del procedimiento de fiscalización tributaria." THĒMIS-Revista de Derecho, 2014. http://repositorio.pucp.edu.pe/index/handle/123456789/107268.
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The object of the principle of material truth is to assure the certainty of facts in order to be able to issue a ruling as close to reality as possible. The principle has an intimate relationship with the limitation periods which, as regulated in our Tax Code, are only established as minimum terms in which the tax debt or has to comply with the administration’s requirements, without specifying any maximum. The author explains how it is that the terms regarding the presentation of documents have to be fixed considering the civilian’s interestand not against it. He affirms that, as long as the collection procedure of a certain period has not concluded, the debtor has the faculty to offer information and arguments to the administration in order to sustain his statement, allowing him to discuss the objections formulated against him.El principio de verdad material tiene por finalidad arribar a la certeza de los hechos para poder emitir un pronunciamiento lo más cercano posible a la realidad. Está vinculado con los plazos de preclusión que, en nuestro CódigoTributario, sólo están establecidos como plazos mínimos para que el deudor tributario cumpla con lo solicitado por la administración, sin señalar un plazo máximo. El autor explica cómo los plazos para presentarlos documentos deben ser fijados según el interés del administrado y no en perjuicio de éste; mientras no concluya el procedimiento administrativo de fiscalización por el período y ejercicio fiscal correspondiente, el deudor tributario se encuentra plenamente facultado para ofrecer la información y los argumentos que sustenten sus descargos, pudiendo levantar de ese modo que los reparos que se le han formulado.
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Horváthová, Ľubica. "Vliv hloubkové mozkové stimulace na konektivitu lidského mozku." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-316805.
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Hĺbková mozgová stimulácia (DBS) predstavuje účinnú liečbu pre pacientov s Parkinsonovou chorobou (PD) alebo farmakorezistentnou epilepsiou. Avšak mechanizmy, ktorými znižuje počet záchvatov a zlepšuje pohyb, zostávajú ešte do značnej miery neznáme. Pre lepšie pochopenie a určenie, v ktorých frekvenčných pásmach je zmena najdôležitejšia, boli urobené porovnania medzi vypnutou a zapnutou DBS pomocou korelačnej metódy a indexu fázového posunu. Jedenásť pacientov s PD a naimplantovanými neurostimulátormi z firiem Medtronic a St.Jude Medical bolo predmetom nahraných dát použitých v tejto práci. Výsledky dokazujú, že zmena konektivity počas DBS nastane a zároveň, že najviac ovplyvňuje najvyššie frekvencie ako beta, nízka gama a vysoká gama. Zmeny v týchto frekvenciách, zodpovedné za motorickú aktivitu, sústredenie a spracovanie informácií, sú v súlade s klinickou teóriou o PD. Počas tejto choroby je patologická beta aktivita hypersynchronizovaná a gama aktivita je znížená práve v motorických oblastiach. Ak sa gama aktivita počas zapnutej stimulácie zvyšuje, fyziologický stav pacientov sa čiastočne znovuobnovuje a tým zlepšuje ich hybnosť. Metódy a výsledky tejto práce budú použité pre ďalší výskum pacientov s PD a epilepsiou.
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Pham, Toan Thang. "Advances in opto-electronic oscillator operation for sensing and component characterization." Thesis, Cachan, Ecole normale supérieure, 2015. http://www.theses.fr/2015DENS0013/document.
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L'oscillateur optoélectronique (OEO) a été introduit pour la première fois en 1996 par S. Yao et L. Maleki, en tant qu'oscillateur microondes à très faible bruit de phase et obtenu par synthèse directe. Les développements de l'OEO concernent les applications en photonique microondes, télécommunications optiques, radar et traitement du signal. Mais l'OEO devrait aussi pouvoir être utilisé dans le domaine des capteurs. Dans cette thèse nous étudiants plusieurs aspects de l'OEO pour son application à la mesure d'indice de réfraction d'un liquide. Compte tenu de sa structure l'OEO dépend fortement des conditions ambiantes d'utilisation. S'il n'est pas bien optimisé ni contrôlé, il ne peut pas fonctionner correctement sur une longue durée. Nous avons étudié les influences de la température sur le modulateur électrooptique (EOM) et sur le comportement global de l'OEO. Un contrôle de température réduit de façon significative le phénomène de dérive de l'EOM. Afin de la supprimer complètement, nous avons mis au point une instrumentation construite autour d'une carte DSP, permettant de détecter et compenser la dérive du point de fonctionnement optique de l'EOM tout en contrôlant simultanément sa température. Une première technique est basée sur un signal de test, basse fréquence, appliqué à l'électrode DC du modulateur. Une deuxième solution consiste à travailler sur la puissance optique en sortie du modulateur. En combinant les deux on peut profiter des avantages de ces deux méthodes. Utilisant ainsi l'OEO nous avons testé plusieurs configurations pour mesurer l'indice de réfraction de quatre solutions chimiques bien connues, nous avons obtenu une variance de 3 pour mille. Les résultats sont en assez bon accord avec les publications correspondantes. Enfin nous avons aussi introduit une nouvelle méthode pour améliorer les mesures d'indice de réfraction faites à long terme en suivant, grâce à un analyseur vectoriel de réseau, les évolutions au cours du temps du temps de propagation dans la fibre optique. En introduisant à partir de cette mesure une correction aux mesures de la fréquence d'oscillation il est possible de réduire les fluctuations de cette fréquence à seulement 606 Hz, sur une durée de 62 h, ce que l'on peut comparer aux 8 GHz de l'oscillateur. Ainsi le rapport signal à bruit, peut être grandement amélioré lors de la mesure d'indice de réfraction et il doit être possible de diminuer la limite de détection des variations de l'indice de réfraction au cours du tempsThe optoelectronic oscillator (OEO) was first introduced in 1996 by S. Yao and L. Maleki as a very low phase noise microwave oscillator working in direct synthesis. The OEO developments concern applications in microwave photonics, optical telecommunication, radar and high speed signal processing systems but it should also be used in the sensing domain. In this thesis, we study several aspects to apply the OEO to liquid refractive index measurement. Because of its structure the OEO is very dependent on the ambient conditions. If the OEO is not optimized and controlled, it cannot operate well for long duration. We have analyzed the influences of temperature on the electrooptic modulator (EOM) and the global OEO behavior. Temperature control can significantly reduce the drift phenomena of the EOM. In order to totally remove this drift, we have developed a complete digital system, based on a DSP kit, to detect and compensate automatically the EOM optical bias point drift and to control simultaneously its temperature. The first technique is based on a dither signal at low frequency, injected to DC electrode of the EOM. The second one is based on the average optical output power of the EOM. A combination of these two techniques can take advantages from both of them. Using like that the OEO, we have tested several configurations to measure the refractive index of four classical chemical solutions leading to a standard deviation of 3 per thousand. The results are in rather good agreement with previous publications. Finally, we have introduced a new method to improve the long-term refractive index measurement by monitoring, with a vector network analyzer, the variations of the optical delay in the fiber loop of the OEO. Introducing by this way a correction to the long-term frequency measurement it is possible to reduce the oscillation frequency fluctuations to only 606 Hz, compared to the 8 GHz of the oscillator, for a duration of 62 hours. Therefore the signal-to-noise ratio in the refractive index measurement can be enhanced and so the detection resolution of the refractive index variations during time
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Gottapu, Manohar. "Two-phase flow: buoyancy driven flow of a partially miscible droplet at low Reynolds number a thesis presented to the faculty of the Graduate School, Tennessee Technological University /." Click to access online, 2009. http://proquest.umi.com/pqdweb?index=0&did=2000384971&SrchMode=1&sid=3&Fmt=6&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1279288319&clientId=28564.
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Ševčík, Michal. "Nanometrologická vibrometrie." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220217.
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This thesis deals with the precise measurement of distances in nanometer range at ultrasonic frequencies for the purposes of vibrometry. The paper is primary focused on~nanometric displacement measurement methods. First the thesis deals with the physical phenomena based on light in the theoretical section. This includes interference of light, index of refraction, polarization, interferometry and more. Understanding of these physical laws is crucial for design and assembling of the interferometer. Subjects of interferometric method for precise and fast measurement of the nanometric displacement and vibration are discussed. Interferometer components such as lasers, photodetectors and optical elements are described are described in the final part of this section. Practical section of thesis can be divided into two parts. The design and assembling issues are discussed in the first section. Many problems which I had to solve are described. Control software and implementation of the signal processing is the subject of the second part. I met with particular problems such as phase unwrapping. I solved this problem of discontinuous phase field with user written algorithm. Finally the graphical user interface was created. Using assembled interferometer and written software application I measured vibration of Langevin transducer on ultrasonic frequencies.
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Malléjac, Matthieu. "Metamaterials with extreme properties for the control of acoustic waves." Thesis, Le Mans, 2020. http://cyberdoc-int.univ-lemans.fr/Theses/2020/2020LEMA1024.pdf.
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Les métamatériaux à indice nul, pour lesquels au moins un des paramètres effectifs s’annule (densité ou compressibilité dynamique pour l’acoustique), ont fait l’objet d’une attention considérable au cours de ces dernières années. Ces matériaux ont la particularité d’induire une augmentation remarquable de la longueur d’onde effective, offrant ainsi de nombreuses possibilités d’application, incluant entre autres la propagation sans changement de phase, la dissimulation acoustique de diffuseurs, le contrôle de la directivité, etc. Ce travail de doctorat se concentre particulièrement sur le régime de densité effective quasi-nulle dans des métamatériaux acoustiques constitués de plaques fines dans l’air. Grâce à une étude approfondie d’un arrangement périodique de fines plaques élastiques encastrées dans un guide d’onde, nous avons pu explorer analytiquement, numériquement et expérimentalement certains des effets ci-dessus. Une attention particulière est portée sur les pertes inhérentes à ce type de système et à leurs conséquences sur les comportements attendus. Nous débutons par l’étude numérique et l’observation expérimentale d’une propagation sans changement de phase à travers le métamatériau, à une fréquence située dans une bande interdite du système fini. Nous transposons ensuite le concept de dopage photonique à l’acoustique. L’ajout dans le système d’une impureté, ici un résonateur de Helmholtz bien choisi, permet de transformer le régime de densité nulle en un régime où la densité et la compressibilité sont simultanément quasi-nulles. Ainsi, la propagation sans changement de phase est accompagnée d’une transmission unitaire, due à l’accord d’impédance du système avec l’air environnant. Nous étudions enfin la possibilité de réaliser une dissimulation ou un masquage acoustique d’un objet en utilisant l’extension de la longueur d’onde acoustique, offerte par la densité nulleZero-index metamaterials, for which at least one of the effective parameters (density or dynamic compressibility for acoustics) vanishes, have received considerable attention in recent years. These materials have the particularity of inducing a considerable increase in the effective wavelength, thus offering numerous application possibilities, including, among others, propagation without phase change, acoustic hiding of diffusers, directivity control, etc. This PhD work focuses particularly on the near-zero effective density regime in acoustic metamaterials made of thin plates in air. Through an in-depth study of a periodic arrangement of thin elastic plates embedded in a waveguide, we have been able to explore analytically, numerically and experimentally some of the above effects. Particular attention is paid to the losses inherent to this type of system and their consequences on the expected behavior. We begin by studying numerically and experimentally observing a phase-change-free propagation through the metamaterial at a frequency in a stopband of the finite system. We then transpose the concept of photonic doping to acoustics. The addition of an impurity, here a well-chosen Helmholtz resonator, to the system allows to transform the regime of zero density into one where density and compressibility are simultaneously near zero. Thus, propagation without phase change is accompanied by a unitary transmission, due to the impedance matching of the system with the surrounding air. Finally, we study the possibility of performing acoustic hiding or masking of an object using the acoustic wavelength stretching offered by the zero density
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Strömqvist, Gustav. "Nonlinear response in engineered optical materials." Doctoral thesis, KTH, Laserfysik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-92221.
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Material and structure engineering are increasingly employed in active optical media,in this context defined as media capable of providing laser or/and optical parametric gain. For laser materials, the main aim of the engineering is to tailor the absorption and emission cross sections in order to optimise the laser performance. At the same time, the engineering also results in a collateral modification of the material’s nonlinear response. In the first part of this work, the nonlinear index of refraction is characterised for two crystallographic forms of laser-ion doped and undoped double-tungstate crystals. These laser crystals have broad gain bandwidths, in particular when doped with Yb3+. As shown in this work, the crystals also have large Kerr nonlinearities, where the values vary significantly for different chemical compositions of the crystals. The combination of a broad gain bandwidthand a high Kerr nonlinearity makes the laser-ion doped double tungstates excellent candidates to employ for the generation of ultrashort laser pulses by Kerr-lens modelocking. The second part of the work relates to the applications of engineered second-order nonlinear media, which here in particular are periodically-poled KTiOPO4 crystals. Periodic structure engineering of second-order nonlinear crystals on a submicrometre scale opens up for the realisation of novel nonlinear devices. By the use of quasi-phase matching in these structures, it is possible to efficiently downconvert a pump wave into two counterpropagating parametric waves, which leads to a device called a mirrorless optical parametric oscillator. The nonlinear response in these engineered submicrometre structures is such that the parametric wave that propagates in the opposite direction of the pump automatically has a narrow bandwidth, whereas the parametric wave that propagates with the pump essentially is a frequency-shifted replica of the pump wave. The unusual spectral properties andthe tunabilities of mirrorless optical parametric oscillators are investigated.QC 20120330
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Rannou, Isabelle. "Etudes sous pression de la transition de phase interpolytypique du sulfure de gallium." Paris 6, 1986. http://www.theses.fr/1986PA066063.
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Etude entre 0 et dollar GPA, permettant de mettre en évidence une transition de basse pression à 1,6 GPA; mesures de l'absorption optique et de l'indice de réfraction, de la diffusion Raman et de la diffusion Brillouin; analyse des variations a la transition. Description satisfaisante des variations des modes de vibration au moyen d'un modèle de dynamique réticulaire a forces centrales.
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Xue, Xin. "Health monitoring of drive connected three-phase induction motors from wired towards wireless sensor networks /." Diss., [Riverside, Calif.] : University of California, Riverside, 2009. http://proquest.umi.com/pqdweb?index=0&did=1899497101&SrchMode=2&sid=1&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1269019645&clientId=48051.
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Thesis (Ph. D.)--University of California, Riverside, 2009.Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 20, 2010). Includes bibliographical references. Also issued in print.
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van, der Kolk Jarno Nicolaas. "Theory of Image Formation in Non-linear Optical Microscopy." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36650.
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Nonlinear optical microscopy is a collection of very powerful imaging techniques. Linear optical microscopes probe the refractive index and absorption, which both stem from the first-order linear electric susceptibility. Especially in biological tissue, the variation in the refractive index is often small and the tissue is, in many cases, transparant. Nonlinear optical microscopes on the other hand probe the nonlinear higher-order susceptibilities, which can be chemically sensitive, leading to the capability to achieve label-free imaging.
Nonlinear optical microscopes have been in development for more than thirty years and they are based on numerous nonlinear optical processes. The ones I will concentrate on in this thesis are second harmonic generation (SHG), coherent anti-Stokes Raman scattering (CARS), and stimulated Raman Scattering (SRS). The first technique is commonly used to image collagen as those molecules have a particularly large second-order nonlinear susceptibility due to their chiral structure. CARS and SRS on the other hand are often used because they resonantly target vibrational resonances in molecules, giving rise to the aforementioned label-free imaging.
Deep understanding of the nonlinear imaging process is crucial to the interpretation of the images these techniques produce. Computational tools are exceptionally suited for this task as they allow studying the electromagnetic field anywhere in the sample as well as the far-field, and one can change any of the material properties to study their effect. One such tool is finite-difference time-domain (FDTD) that our group developed for nonlinear optical microscopy simulations. It is a direct discretization of Maxwell's equation. While computationally costly, it does allow any arbitrary shaped sample to be simulated. The sample can have frequency dependent refractive indexes, and also nonlinear media with third-order nonlinearities such as Kerr media and Raman-active media, but also second-order nonlinearities for SHG. The code is designed in such a way that it can run on thousands of CPUs on a wide variety of compute cluster which allows our group to obtain nanoscale resolution.
Another computational tool I use is the free-space Green's function solution to the Helmholtz equation, which can be used to calculate the Hertz vector in the frequency domain, both in the near- and far-field, based on the induced nonlinear polarization. The electric field is then calculated from this Hertz vector. This technique is much faster then FDTD and also allows for arbitrary shapes of the nonlinear electric susceptibility in the sample. However, it assumes a homogeneous refractive index throughout the entire spatial domain and requires complete knowledge of the input beam or beams that induce the nonlinear polarization.
In this thesis, I use these tools to study the image formation process of various nonlinear optical processes mentioned earlier. For example, I study the effect of an inhomogeneous refractive index on the images produced by these microscopes. In literature the index of refraction is almost always assumed to be homogeneous, because, as mentioned before, the inhomogeneity of the refractive index is often small. However, I show that these small differences in the index of refraction can have a significant effect on the measured far-field intensity signal. For example, in SRS and CARS images, the measured signal can increase by an order of magnitude depending on the index mismatch and structure of the sample. Additionally, significant shifts in perceived position occur. Even nonresonant nonlinear signals can be evoked purely through a mismatch in linear refractive index.
Computational modelling can also help reveal additional detail. As SHG is a coherent process, subwavelength information can be inferred through the phase information. Our experimental collaborators built an interferometric SHG (I-SHG) microscope for exactly that purpose. We used this to image collagen fibrils, which are all aligned in a parallel fashion. However, because collagen fibrils have a chiral molecular structure, they can point either ``up'' or ``down''. Using my Green's function simulations of the SHG imaging process of collagen fibrils, I was able to predict the standard deviation in the measured phase and link it to the orientation of collagen fibrils in the focal spot of the probing laser beam, even though the diameters are far below the minimum resolvable capabilities of the microscope. We found that the ``upwards'' fibrils make up 46--53% of the sample.
Even with a normal SHG microscope that does not measures phase, additional subresolution information is obtainable. With our collaborators we measured the ratio of the forward SHG intensity signal to that in the backward direction and with my simulations, we are able to link this to the fibril diameters in collagen tissue. Thus we inferred that the fibril diameter increases as a function of tissue depth.
Furthermore, a computational technique called ptychography is able to retrieve phase information without an interferometric reference beam. Additionally, it increases resolution to the theoretical limit, independent of the laser focal spot size, and corrects for distortions in the input beam as well. I have developed this technique for use with nonlinear optical microscopy and was able to show it is a viable alternative to I-SHG by imaging simulated rat tail tendon at the diffraction limit while retrieving the orientation of the fibrils through the phase of the SHG signal. I also implemented the algorithm for CARS, where the phase information can be used to greatly increase the signal-to-noise ratio by reducing the nonresonant background radiation that results from competing nonlinear optical processes. I showed an example of this by imaging a simulated fibroblast cell where the CARS process was tuned to the lipid droplets inside of the cell. I am currently in talk with experimentalists to apply this theoretical technique to experiments as that would further demonstrate the impact of my work.
Finally, keeping in theme with the collagen fibrils, I show that the ratio of the forward SHG signal to the backward signal, the F/B ratio, is affected by a mismatch in the refractive index for fibrils larger than 100nm. This measure is an indicator of fibril diameter and thus important for making qualitative predictions. Single fibrils are generally too small to be significantly affected by near-field effects, but the bigger fibrils can be. Fibrils in rat tail tendon have a distribution of fibrils diameters and the large fibrils occur infrequent. However, I found that the large fibrils are largely responsible for the forward as well as backward signal, thus refractive index mismatches still affect the F/B ratio significantly despite their infrequency. The F/B ratio for a collection of fibrils placed in a n=1.47 medium was found to be 31.8±0.7% higher than for those in a n=1.33 medium. Our experimental colleagues have done preliminary measurements on mouse tail tendon where they found an increase of 40±20%, in line with the value of 28.1±0.6% that I found for simulations with mouse tail tendon.
In conclusion, the theoretical tools I have used in my thesis have provided me with the ability to study nonlinear optical image formation processes with a level of detail that would be near-impossible to do experimentally. I have used this ability to show how refractive index mismatches, such as those found in biological tissue, can significantly distort the far-field intensity signals. I have shown this for SRS and CARS where the far-field intensity signal appeared an order-of-magnitude larger compared to the same sample without a refractive index mismatch with the background medium. Additionally, shifts in the perceived position of the object under investigation were observed and I showed the presence of a nonresonant background signal in AM-SRS. Likewise I showed that in the SHG imaging of collagen fibrils significant changes in the F/B ratio can occur. All of these effects have important implications as these types of images as biomedical researches rely on the correct interpretation of nonlinear optical microscopy images for both research and diagnostics.
Apart from showing the effect of a refractive index mismatch, I have also shown that computation modelling can be used to infer subwavelength features in SHG imaging experiments of collagen fibril such as fibril orientation and fibril diameter. These methods have the potential to aid medical researchers as changes in the structure of collagen are often an early indicator of diseases such as osteoarthritis.
Finally, I showed that the ptychography algorithm I developed for nonlinear optical microscopy is able to retrieve phase information of the nonlinear electric susceptibility in SHG and CARS imaging while also enhancing the resolution and correcting for distortions in the input beams. I can also use much larger laser spot sizes than in conventional experiments without compromising the obtained resolution, thus fewer measurements are required. The technique is not limited to SHG and CARS either; it will work for other nonlinear optical processes as well. Experimental verification of nonlinear ptychography will be done soon. This technique has to potential to significantly improve current imaging techniques since access to the phase information allows one to observe additional information about the sample as we showed with the I-SHG microscope.
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Bouzid, Abdenbi. "Etude d'optimisation de l'efficacite de diffraction par des materiaux transparents : application a la realisation d'hologramme de phase avec differentes gammes de frequences spatiales." Strasbourg 1, 1987. http://www.theses.fr/1987STR13121.
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Analyse theorique des proprietes des reseaux de phase, conditions d'etude et de realisation des element optiques holographiques pour un certain nombre d'applications. Evaluation du materiau photosensible permettant d'atteindre des efficacites de diffraction tres proches de 100 %. Mise au point d'une methode de suivi de l'evolution du materiau durant le processus de fabrication des composants. Nous pouvons determiner separement les valeurs des indices de refraction et des epaisseurs par interferometrie mach-zehnder
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Büttner, Lars, Felix Schmieder, Martin Teich, Nektarios Koukourakis, and Jürgen Czarske. "Application of adaptive optics for flexible laser induced ultrasound field generation and uncertainty reduction in measurements." SPIE, 2017. https://tud.qucosa.de/id/qucosa%3A35156.
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The availability of spatial light modulators as standard turnkey components and their ongoing development makes them attractive for a huge variety of optical measurement systems in industry and research. Here, we outline two examples of how optical measurements can benefit from spatial light modulators.
Ultrasound testing has become an indispensable tool for industrial inspection. Contact-free measurements can be achieved by laser-induced ultrasound. One disadvantage is that due to the highly divergent sound field of the generated shear waves for a point-wise thermoelastic excitation, only a poor spatial selectivity can be achieved. This problem can be solved by creating an ultrasound focus by means of a ring-like laser intensity distribution, but standard fixed-form optical components used for their generation are always optimised to a fixed set of parameters. Here, we demonstrate, how a predefined intensity pattern as e.g. a ring can be created from an arbitrary input laser beam using a phase-retrieval algorithm to shape an ultrasound focus in the sample.
By displaying different patterns on the spatial light modulator, the focus can be traversed in all three directions through the object allowing a fast and highly spatially resolving scanning of the sample.
Optical measurements take often place under difficult conditions. They are affected by variations of the refractive index, caused e.g. by phase boundaries between two media of different optical density. This will result in an increased measurement uncertainty or, in the worst case, will cause the measurement to fail. To overcome these limitations, we propose the application of adaptive optics. Optical flow velocity measurements based on image correlation in water that are performed through optical distortions are discussed. We demonstrate how the measurement error induced by refractive index variations can be reduced if a spatial light modulator is used in the measurement setup to compensate for the wavefront distortions.
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Lopes, Mirleide Dantas. "Teorema do índice em superfícies curvas de grafeno e fases de Berry." Universidade Federal da Paraíba, 2010. http://tede.biblioteca.ufpb.br:8080/handle/tede/5781.
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The graphene consists of a two-dimensional hexagonal structure formed only by carbon atoms. It is a peculiar molecule, because in low energy its Hamiltonian can be described by the Dirac operator and this gives it some unusual characteristics. In this work the index theorem will be applied to graphene. This allows to estimates the number of zero modes of geometric variants of graphene by means of topological features of these molecules. Finally, it is observed that the index of the Hamiltonian of this system can be described in terms of Berry phases. And so, it is investigated the possibility of doing holonomic quantum computation using the topology of such molecules.
O grafeno consiste em uma estrutura bidimensional hexagonal constituída apenas por átomos de carbono. Trata-se de uma molécula bastante peculiar, pois em baixas energias o seu hamiltoniano pode ser descrito pelo operador de Dirac e isso lhe confere características incomuns. Neste trabalho o teorema do índice será aplicado ao grafeno. Teorema que permite estimar o número de modos zero das variantes geométricas do grafeno por meio das características topológicas destas moléculas. Por fim, observa-se que o índice do hamiltoniano deste sistema pode ser descrito em termos das fases de Berry. E dessa forma, investiga-se a possibilidade de fazer computação quântica holonômica, a partir da topologia de tais moléculas.
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Dipankar, Anurag. "Simulation des grandes échelles de la turbulence atmosphérique : application à l’étude de la propagation des ondes électromagnétiques dans la couche limite atmosphérique." Paris 6, 2010. http://www.theses.fr/2010PA066029.
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Cette thèse traite du couplage de la simulation des grandes échelles (LES) à la propagation des ondes électromagnétiques dans la couche limite atmosphérique. La simulation de la couche limite de convection avec des nuages de faible altitude de type cumulus a été effectuée, et les donnés ont été post-traitées pour la propagation d’ondes électromagnétiques (EM) dans le domaine simulé. La première partie de la thèse porte sur la validation du code LES avec pour trois différentes types de conditions atmosphériques. Les données correspondants à la convection des nuages de faible altitude de type cumulus sont ensuite post-traitées pour obtenir les quantités temporelles d’intérêt pour la modélisation de propagation d’ondes EM. Ces quantités sont les suivantes: la distribution instantanée des indices de réfraction, paramètres locaux de la fonction de structure de l’index de réfraction, échelle caractéristique des structures les plus énergétiques, et échelle caractéristique des échelles dissipatives non résolues. La deuxième partie de la thèse porte sur l’application de ces quantités dans la modélisation de propagation de: ondes radio, ondes optiques, et tourbillons optiques. Une nouvelle méthode a été développée pour étudier la dispersion des ondes radio dans l’atmosphére turbulente. Cette nouvelle méthode établit l’ importance des fluctuations des grandes échelles sur les fluctuations de la phase des ondes radio. Il a été démontrée, via des exemples numériques, que le caractére instationnaire de ces quantités influesur la propagation des ondes optiques.
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Charonko, John James. "Studies of Stented Arteries and Left Ventricular Diastolic Dysfunction Using Experimental and Clinical Analysis with Data Augmentation." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/26875.
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Cardiovascular diseases are among the leading causes of deaths worldwide, but the fluid mechanics of many of these conditions and the devices used to treat them are only partially understood. This goal of this dissertation was to develop new experimental techniques that would enable translational research into two of these conditions. The first set of experiments examined in-vitro the changes in Wall Shear Stress (WSS) and Oscillatory Shear Index (OSI) caused by the implantation of coronary stents into the arteries of the heart using Particle Image Velocimetry. These experiments featured one-to-one scaling, commercial stents, and realistic flow and pressure waveforms, and are believed to be the most physiologically accurate stent experiments to date. This work revealed distinct differences in WSS and OSI between the different stent designs tested, and showed that changes in implantation configuration also affected these hemodynamic parameters. Also, the production of vortices near the stent struts during flow reversal was noted, and an inverse correlation between WSS and OSI was described.
The second set of experiments investigated Left Ventricular Diastolic Dysfunction (LVDD) using phase contrast magnetic resonance imaging (pcMRI). Using this technique, ten patients with and without LVDD were scanned and a 2D portrait of blood flow through their heart was obtained. To augment this data, pressure fields were calculated from the velocity data using an omni-directional pressure integration scheme coupled with a proper-orthogonal decomposition-based smoothing. This technique was selected from a variety of methods from the literature based on an extensive error analysis and comparison. With this coupled information, it was observed that healthy patients exhibited different flow patterns than diseased patients, and had stronger pressure differences during early filling. In particular, the ratio of early filling pressure to late filling pressure was a statistically significant predictor of diastolic dysfunction. Based on these observations, a novel hypothesis was presented that related the motion of the heart walls to the observed flow patterns and pressure gradients, which may explain the differences observed clinically between healthy and diseased patients.Ph. D.
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Latham, Tina Joy. "Structure and properties of MTiOXOâ†4 crystals." Thesis, University of Warwick, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364604.
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Kim, Hyeongeu. "Investigation of optical properties of polymethines for potential application in all-optical signal processing." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53579.
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Demonstration of ultrafast all-optical signal processing (AOSP) using silicon as the active material has been limited by large two-photon absorption loss and long lifetimes of the resulting free carriers. For AOSP at speeds in the terahertz, an order of magnitude faster than that the fastest current electronic counterpart, a class of π-conjugated organic molecules called polymethines provides a promising alternative to silicon as they possess large third-order nonlinearities, and ultrafast polarization response to an incident field. The challenge in the application of polymethines as active nonlinear optical materials for AOSP is in translating their promising molecular properties into bulk material properties. The large linear polarizability and charged nature of the polymethines molecules strongly promote aggregation and phase-separation in solid blends, offsetting their advantageous molecular optical properties. In this work, polymethines’ resistance to deleterious spontaneous symmetry breaking and aggregation was enhanced by substitutions of metal- and chalcogen- containing terminal groups, and rigid steric groups above and below the π-conjugated plane of polymethine chain. The resulting polymethines/amorphous polycarbonate (APC) blend films demonstrated an unprecedentedly high two-photon figure-of-merit, |Re(χ(3))/Im(χ(3))| and low linear loss. The optical quality of the polymethines/APC films was also improved by replacing the commonly-used alkyl ammonium counterions with more polarizable aryl phosphonium counterions with moderate ground state dipole moment. The resulting dye-polymer blend films showed an enhanced near-infrared transparency while its magnitude of the third-order susceptibility, |χ(3)|, showed a good agreement with that extrapolated from the molecular third-order polarizability, γ. For facile integration of these promising organic materials into SOH, the substrate surface was functionalized using silane coupling chemistry for the reduction of surface energy mismatch between the polymer films and the waveguide containing substrates. The optical and SEM micrographs showed vastly improved coverage and infiltration of the microfeatures. Furthermore, to enable the precise engineering of waveguide cross-sectional dimensions for single-mode propagation in the organic cladding, the dispersion curves of the polymethines/polymer blends were generated using prism coupling and ellipsometry. The combined efforts in the development of molecules and materials discussed in the thesis have culminated into a successful identification and optimization of the polymethines dyes and their polymer blends for imminent demonstrations of on-chip AOSP at terahertz speed.
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Nadji, Séverin Landry. "Développement de systèmes de contrôle in situ des propriétés optiques de filtres interférentiels." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0155.
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La réalisation de fonctions de filtrage complexes nécessite une parfaite maîtrise du processus de dépôt ainsi qu’un contrôle précis et en temps réel de l’épaisseur optique des couches déposées. Au cours de ma thèse, consacrée au développement de nouvelles modalités de contrôle optique in situ, je me suis particulièrement intéressé à deux sujets différents, à savoir : - D’une part, la détermination de la dépendance spectrale des constantes optiques (indice de réfraction et coefficient d’extinction) de matériaux diélectriques. Un moyen possible pour effectuer cette détermination consiste à utiliser un système de contrôle optique large bande afin d’enregistrer les spectres de transmission de l’empilement au fur et à mesure de sa formation. En effet, l’évolution temporelle, à chaque longueur d’onde, de ces spectres de transmission contient des informations quantitatives liées aux constantes optiques que nous souhaitons déterminer. - D’autre part, la mesure en temps réel du coefficient de réflexion (r) d’un empilement, en amplitude et en phase, lors de son dépôt. En effet, les méthodes de contrôles optiques en intensité présentent des limitations que la connaissance de l’information de phase devrait permettre de contourner. Cette mesure est réalisée par interférométrie holographique digitale à faible cohérence sur un substrat éclairé par sa face arrière et dont la face avant est équipée d’un masque annulaire. Ceci donne accès aux information de phase et d’amplitude recherchées tout en s’affranchissant des vibrations générées par le fonctionnement de la machine de dépôt ainsi que du mouvement de rotation à 120 tours par minute qu’effectue le porte-substratThe realization of complex filtering functions requires a perfect mastering of the deposition process as well as an accurate real time monitoring of the optical thickness of the deposited layers. During my PhD thesis, devoted to the development of new methods of in situ optical monitoring, I was particularly interested in two different subjects, namely:- On the one hand, the determination of the spectral dependence of optical constants (refractive index and extinction coefficient) of dielectric materials. A possible way to achieve this determination consist in using a broadband optical monitoring system in order to record the transmission spectra, in real time, of the stack during its formation. Indeed, the temporal evolution, at each wavelength, of these transmission spectra provide quantitative information related to the optical constants that we wish to determine.- On the other hand, the real time measurement of the reflection coefficient (r) of a stack, in amplitude and phase, during its deposition. Indeed, the optical monitoring methods based on intensity proprieties present some limitations that the knowledge of phase information should overcome. This measurement is performed by low coherence digital holographic interferometry on a substrate illuminated by its rear face and whose front face is equipped with an annular mask. This gives access to desired phase and amplitude information while avoiding the parasitic influence of the substrate motions induced by the vibrations of the deposition machine, and the rotation of the substrate holder at 120 rounds per minute
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Onofri, Fabrice. "Prise en compte de la dimension finie des faisceaux d'éclairage en granulométrie optique : anémométrie phase Doppler. diagnostics des milieux diphasiques." Phd thesis, Université de Rouen, 1995. http://tel.archives-ouvertes.fr/tel-00287923.
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Le diagnostic par une méthode optique telle que l'anémométrie phase Doppler, des particules présentes dans les milieux diphasiques, nécessite l'emploi de faisceaux laser focalisés. La compréhension et l'élimination des effets engendrés sur les mesures de taille, par les gradients d'éclairage ou les « effets de trajectoire », est au centre de la première partie de cette thèse. Différentes solutions, testées numériquement et expérimentalement, sont proposées pour éliminer les biais constatés. L'extension de l'anémométrie phase Doppler à la mesure de la partie réelle et complexe (absorption) de l'indice de réfraction des particules est ensuite considérée. Les méthodes originales proposées autorisent, en plus des mesures de taille et de vitesse, la reconnaissance des particules par leur indice, l'étude de la coalescence de gouttes (liquides transparents ou absorbants) ou la détection des fortes variations de température de particules. La dernière partie de ce travail propose diverses solutions pour étendre l'anémomètrie phase Doppler à la mesure de particules cylindriques (fibres, jets liquides), ovoïdes (oblates/problates), sphériques nonhomogènes (multicouches, à coeur, hétérogènes: diphasiques ou non) et irrégulières. Le cas des particules multicouches est particulièrement détaillé, à partir de simulations basées sur le travail théorique effectué pour étendre la théorie de Lorenz-Mie généralisée à ce type de particules.
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Karugaba, Sosthenes Francis. "Dynamics and control of a five phase induction machine a thesis presented to the faculty of the Graduate School, Tennessee Technological University /." Click to access online, 2008. http://proquest.umi.com/pqdweb?index=0&did=1619620261&SrchMode=1&sid=2&Fmt=6&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1268924899&clientId=28564.
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Lima, Filho Elton Soares de. "Medida interferométrica automática de atividade bacteriana." Universidade Federal de Juiz de Fora (UFJF), 2009. https://repositorio.ufjf.br/jspui/handle/ufjf/5354.
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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Neste trabalho apresenta-se os princípios, a construção e o funcionamento de um aparato que realiza medidas interferométricas de atividade metabólica de microorganismos, em tempo real e de várias amostras simultaneamente. A construção do MAI1 compreende o desenvolvimento e implementação de técnicas de posicionamento das amostras, controle preciso de temperatura, bem como a aquisição e interpretação de padrões de sinais modulados de interferência óptica. Ao longo deste trabalho serão apresentados os modelos teóricos utilizados, os códigos de computador, os desenhos dos circuitos eletrônicos e da mecânica do aparato, bem como medidas realizadas com o mesmo.
This work presents the principles, construction and functioning of an apparatus wich measures the metabolic activity of microorganisms, in real time and from different samples simultaneously, using optical interferometry. The construction of MAI' required the development and implementation of techniques for positioning of samples, precision control of temperature, as well as the acquisition and interpretation of patterns of modulated optical interference signals. Along this work the theoretical models used, the computer codes, the electronic circuit drawings, and the mechanics of the apparatus, as well as measurements carried out with it, will be presented.
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PELENC, DENIS. "Elaboration par epitaxie en phase liquide et caracterisation de couches monocristallines de yag dope : realisation de lasers guide d'onde neodyme et ytterbium a faibles seuils." Grenoble 1, 1993. http://www.theses.fr/1993GRE10171.
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Dans le cadre des recherches sur des dispositifs laser compacts pouvant etre pompes par diodes, ce memoire decrit le developpement d'une nouvelle technique d'elaboration de lasers guides d'onde, l'epitaxie en phase liquide. Cette technique a ete appliquee a la croissance de couches minces monocristallines de yag dope neodyme et ytterbium sur des substrats de yag non dope. Afin d'obtenir des guides de bonne qualite, nous avons defini les conditions de croissance des couches et montre l'interet de la croissance d'une surcouche de confinement. Deux co-dopages ont ete etudies en supplement a l'ion actif: gallium pour controler l'indice optique des couches, lutetium pour controler leur parametre cristallin. La determination du coefficient de segregation des divers dopants a requis le developpement d'un modele qui prend en compte l'evolution des bains au cours du temps. Nous avons mesure l'augmentation d'indice due a chaque dopant et propose un mecanisme expliquant cette augmentation. La caracterisation spectroscopique des couches a indique que les ions actifs ont les memes proprietes que le materiau massif de meme composition. La caracterisation laser a montre des pertes par propagation tres faibles (environ 0,1 db/cm), comparables a celles du materiau massif. Pour la transition laser a 1064 nm du neodyme, nous avons demontre l'effet laser pour une puissance absorbee au seuil de 700 w et mesure un rendement differentiel de 40% en pompage par diode, pour un seuil de 14 mw. Pour des transitions laser quasi-3 niveaux, une diminution significative du seuil par rapport a une configuration non guidee a ete obtenue: a 946 nm dans un guide dope neodyme, a 1029 nm dans un guide dope ytterbium en pompage par barrette de diode 1w. Un rendement differentiel de 80% a egalement ete mesure dans un guide dope ytterbium emettant a 1048 nm
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Misoguti, Lino. "Estudo das propriedades ópticas lineares e não-lineares de cristais de l-alanina, l-treonina e l-lisina." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-06062007-190720/.
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Neste trabalho estudamos uma nova classe de materiais ópticos não-lineares, os cristais orgânicos, que possuem potencial para muitas aplicação em dispositivos. Determinamos diferentes propriedades ópticas lineares e não-lineares de três cristais orgânicos: a l-alanina, a l-treonina e a l-lisina. Esses cristais de aminoácido foram escolhidos por apresentarem propriedades de geração de segundo harmônico (GSH) e por serem materiais nunca estudados sob o ponto de vista da óptica não-linear. Estudamos algumas das propriedades ópticas lineares fundamentais desses cristais biaxiais transparentes, pois deles dependem os fenômenos não-lineares sobre os quais são feitas intensas pesquisas. Determinamos as propriedades lineares como os espectros de absorção, os índices de refração, os eixo ópticos, velocidade de propagação da luz num meio anisotrópico e os limiares de dano por radiação. Posteriormente, determinamos as condições de casamento de fase, a eficiência de GSH, e a auto-modulação de fase. A GSH e a auto-modulação de fase pertencem, respectivamente, a processos não-lineares de segunda e de terceira-ordem. Para o estudo de muitas dessas propriedades foram desenvolvidas novas técnicas experimentais. Uma dessas novas técnicas, a varredura-Z oscilante, teve sensibilidade para determinar, pela primeira vez, o índice de refração não oscilante, vez, o índice de refração não linear desses cristais orgânicos. Além disso, como a todos os processos de caracterização envolveram a preparação de amostras, tivemos a oportunidade de criar procedimentos padrões para manipulação e utilização desses novos materiais.In this work we studied a new class of nonlinear organic crystals that are potential candidates for devices application. We determined several linear and nonlinear optical properties of three organic crystals: l-alanine, l-threonine and l-lysine. These aminoacid. These aminoacid because their nonlinearities were never studied before. We characterized some of the fundamental linear optical properties of these biaxial transparent crystals, because they have influence on nonlinear phenomena that attracted a lot of research. We determined linear properties like absorption spectra, indices of refraction, optical axes, the light speed propagation in anisotropy media and the optical damage threshold. Subsequently, we determined the phase-matching condition for SHG, efficiency of the SHG and self-phase modulation. The SHG and self-phase modulation belongs, respectively, to the second-order and third-order nonlinear processes. To study several of these properties we had to develop some new experimental techniques. One of them, the oscillatory Z-scan, allows enough sensibility to determine, for the first time, the nonlinear refraction index of these organic crystals. Besides, as all these optical characterization involve the preparation of the samples, we had the opportunity to establishing standard procedures for manipulation of these new materials.
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Seif, Tory A. "A campus-wide prevention and early intervention program for unwanted pursuit behaviors (stalking) : phase I ; development, implementation, and evaluation of a brief education and awareness program /." Full text available from ProQuest UM Digital Dissertations, 2006. http://0-proquest.umi.com.umiss.lib.olemiss.edu/pqdweb?index=0&did=1331395761&SrchMode=1&sid=2&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1218810646&clientId=22256.
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Děcká, Klára. "Interferometrické měření fázových změn optického svazku v turbulenci." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377040.
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This master’s thesis deals with the impact of atmospheric turbulence on phase changes of a free space optical signal. This problematic is investigated by the interferometric method. A part of the thesis is focused on the phenomenon of atmospheric turbulence. Then the physical effect of interference is discussed and optical interferometers are described. The experimental part of the thesis is focused on measurement of phase shift of optical signal by interferometric method. The result of the thesis is to determine how phase shift of an optical beam depends on the strength of turbulence.
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Nováková, Lucie. "Snížení nákladů na výrobu odlitků ze slitin hliníku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-228993.
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This thesis deals with solving the most serious internal defects in castings made of aluminum alloys which are cast in sand molds in Slévárna a modelárna Nové Ransko Ltd. The problem solving contains a description of the problematic castings with the investigation of the structure and phases and subsequent detailed analysis of their production. The Author of this thesis also examines the influence of Fe and Mn on a possible formation of the internal porosity with the help of test meltings with the evaluation of the internal structural change. The Author’s design solution is a close checking of chemical composition with regard to the ratio Mn / Fe present in the alloy, the purchase of Foundry Degassing Unit to reduce gassiness of melted metals and better control of gassiness with the help of the appropriate equipment for the density Dichte index.
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Sabard, Jérémy. "Etude de l'explosion de mélanges diphasiques : hydrogène et poussières." Thesis, Orléans, 2013. http://www.theses.fr/2013ORLE2022.
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Cette étude s’inscrit dans le cadre de la sûreté de l’installation ITER. En effet, des études d’accidentologie concernant cette installation ont permis de mettre à jour un risque d’explosion de mélanges à base d’hydrogène et de poussières. L’objectif de la thèse est d’acquérir les données fondamentales caractérisant l’explosion de ces mélanges diphasiques permettant ainsi d’évaluer les pressions générées par une éventuelle explosion des poussières qu’elle soit concomitante on non à celle de l’hydrogène. Pour se faire, des expériences, en bombe sphérique, ont été réalisées concernant des mélanges gazeux hydrogène - oxygène - azote. Les expériences ont été accomplies pour des températures de 303 et 343 K et des pressions de 50 et 100 kPa pour différentes concentrations en hydrogène et différents rapports N2/O2 dans le mélange. Les paramètres de caractérisation de l’explosion de ces mélanges ont été déterminés tels que la pression maximale de combustion (PMAX), l’indice de déflagration (KG ou KST), le temps de combustion (tC), la vitesse fondamentale de flamme (SL°) et la longueur de Markstein (LB). Une modélisation cinétique de la vitesse de flamme utilisant le code COSILAB a été réalisée, permettant de déduire la vitesse fondamentale de flamme sur la base de trois mécanismes cinétiques détaillés de la littérature. Celle-ci a permis l’évaluation de l’énergie d’activation globale sur la base du modèle cinétique présentant le meilleur accord avec l’expérience. De plus des calculs thermodynamiques à l’équilibre ont été réalisés afin de comparer les pressions maximales de combustion aux valeurs théoriques. Pour les mélanges diphasiques, un nouveau système d’introduction des poussières a été mis en place et des expériences caractérisant les paramètres d’explosion de ces mélanges ont été réalisées dans la bombe sphérique. Celles-ci ont permis de mettre en exergue le fait qu’une explosion de poussières, sous certaines conditions peut-être concomitante à une explosion d’hydrogèneThe context of the study is the safety of the ITER installation. Indeed, studies have shown that it exists a risk for two-phase mixtures of hydrogen and dust can explode and create a safety risk for the ITER installation. This aims to obtain the fundamental data which characterize the explosion of these mixtures and to evaluate the pressure loads they can generate. To do so, experiments in spherical bomb have been carried out for hydrogen - oxygen - nitrogen mixtures at two initial temperatures (303 and 343 K) and pressures (50 and 100 kPa) for different hydrogen concentrations and different N2/O2 ratios. Explosion parameters like maximum combustion pressures (PMAX), deflagration indexes (KG or KST), combustion times (tC), fundamental flame speeds (SL°) and Markstein lengths have been determined. A kinetic modelling of the flame speed, using the COSILAB software was performed based on three detailed kinetic models available in the literature and allowed the calculation of the global activation energy on the basis of the kinetic model which showed the best agreement with the experimental data. Moreover equilibrium calculations were achieved to compare PMAX to the theoretical values. For two-phase mixtures, a new introduction device was tested and set up and experiments characterizing the explosions parameters of the two-phase mixtures have been performed in the spherical bomb. They were able to stress out the fact that, under some circumstances, dust explosion can be concomitant to a hydrogen explosion
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Salmazo, Carla Alexandra Almeida. "Parâmetros de avaliação nutricional para detectar desnutrição em pacientes com AIDS em tratamento com antirretrovirais." Universidade do Estado do Rio de Janeiro, 2010. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=3286.
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A avaliação do estado nutricional em pacientes com HIV é de grande importância, pois as conseqüências provocadas pelo processo patológico da doença estão associadas com perda de peso corporal, massa magra e desnutrição grave, o que prediz aumento da morbimortalidade. Os valores de linfometria CD4 também têm sido utilizados como preditores a curto e médio prazo para o desenvolvimento de infecções oportunistas, as quais são incomuns em pacientes com CD4 >200 cels/mm3. Partindo deste conhecimento, optou-se por estudar o estado nutricional de homens e mulheres HIV positivos de acordo com a contagem de células CD4. Utilizou-se como parâmetros nutricionais o índice de massa corporal (IMC), a área muscular do braço corrigida (AMBc), albumina sérica e o ângulo de fase (AF). Foram estudados 39 pacientes HIV positivos, acompanhados pelo ambulatório de doenças infectoparasitárias do Hospital Universitário Pedro Ernesto (HUPE/UERJ). Não foi observada desnutrição na população estudada, quando avaliada pelo IMC e albumina em ambos os sexos, independente do número de células CD4. Entretanto, a AMBc e o AF, tanto nos homens quanto nas mulheres, demonstraram comprometimento nos parâmetros de massa magra. Em relação à associação entre os indicadores nutricionais e o número de células CD4, foi observado correlação significante com a AMBc e a albumina no grupo estudado. A correlação de acordo com o sexo manteve-se significante em ambos os grupos para AMBc e com uma tendência positiva (p=0,06) entre o AF e CD4 no grupo dos homens. Portanto, estes resultados demonstram que para avaliar o estado nutricional, principalmente o compartimento de massa corporal magra de pacientes HIV positivos sob terapia antirretroviral, é preciso utilizar indicadores mais sensíveis, mesmo naqueles pacientes com melhor estado de controle da doença.The assessment of nutritional status in patients with HIV is of great importance, because the consequences caused by the pathological process of the disease are associated with weight loss, lean body mass and severe malnutrition, which predicts increased morbidity and mortality. The values of CD4 linfometria have also been used as predictors of short and medium term development of opportunistic infections, which are uncommon in patients with CD4 counts > 200 cells/mm3. Based on this knowledge, we chose to study the nutritional status of HIV positive men and women according to CD4 cell count. Participants had the following nutritional parameters assessed: body mass index (BMI), corrected arm muscle area (AMA), serum albumin and the phase angle (PA). We studied 39 HIV-positive patients, under treatment in a infectious diseases clinic of the University Hospital Pedro Ernesto (HUPE). None of patients has malnutrition according BMI and albumin in both sexes, regardless of the number of CD4 cells. However, in men and women to AMA and the PA, have demonstrated reductions in parameters of lean body mass. Regarding the association between nutritional indicators and the number of CD4 cells, we observed a significant correlation with the AMA and albumin in the study group. The correlation according to gender remained significant in both groups for AMA and a positive trend (p = 0.06) between the PA and CD4 in males. Therefore these results demonstrate that to assess nutritional status, especially the compartiment of lean body mass in HIV positive patients under antirretrovirals, it is necessary to use more sensitive, even in patients with the best state of disease control.
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Jean, Marc Henri. "Multi-Constellation GNSS Scintillation at Mid-Latitudes." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/73704.
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Scintillation of Global Positioning Systems (GPS) signals have been extensively studied
at low and high latitude regions of the Earth. It has been shown in past studies that amplitude
scintillation is severe at low latitudes and phase scintillation is severe at high latitudes. Unlike
low and high latitude regions, mid-latitude scintillation has not been extensively studied. Further, it has been suggested that mid-latitude scintillation is negligible. The purpose of this research is to challenge this belief.
A multi-constellation and multi-frequency receiver, that tracks American, Russian, and
European satellites, was used to monitor scintillation activity at the Virginia Tech Space Center.
Analysis was performed on collected data from various days and compared to past research done at high, mid, and low latitudes. The results are discussed in this thesis.Master of Science