Design considerations and experimental results of a dual-band circularly polarized stacked microstrip antenna for GPS operations at 1227 and 1575 MHz are presented. The antenna is achieved by stacking two corner-truncated square microstrip patches. The obtained circular polarization (CP) bandwidths, determined from 3-dB axial ratio, are about 15 MHz (about 1.2%) and 17 MHz (about 1.1%) at 1227 and 1575 MHz, respectively. Good CP radiation patterns and antenna gain have also been observed.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1983. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 138-140).

In this research work, we propose a novel energy harvester which converts solar electromagnetic radiation into DC energy at infrared regime. The proposed device consists of a dual polarized nanoantenna loaded with an anisotropic material at its gap. The dual polarized nanoantenna focuses the randomly polarized radiation into its gap resulting in high electric field. This high local electric field at the gap interacts with the anisotropic material. In our proposed design, the anisotropic material possesses nonlinear electrical conductivity and converts the dual polarizations at the gap into a DC voltage difference across the terminals of the nanoantenna. The novelty of our proposed design is in the rectification of the electromagnetic radiation without utilizing a diode. The theory of the energy harvester depends on the utilization of the dual polarized nanoantennas at high frequency regime. Therefore, we carry out a parametric study to investigate the resonance characteristic of the dual polarized nanoantenna. In addition, we investigate the effect of the geometrical parameters on the local field enhancement at the gap of the dual polarized nanoantenna. Also, another parametric study is carried out to determine the effect of the governing parameters of the anisotropic material on the generated DC voltage across the harvester. Our approach is illustrated through electromagnetic simulations. / Thesis / Master of Applied Science (MASc)

Owing to the need of high-directivity radiation in fix-point communication, this thesis designs the metamaterial with 4-fold rotational symmetric unitcells. Using their nearing-zero refractive index along two polarizations, we can get gain-enhanced antenna radomes and place them above dual- and circular-polarized antenna to verify our idea. It is known that the group delay variation in a communication system causes the degradation of symbol error rate, and positive group delay (GD) causes delay in signal propagation. Therefore, this research studies the negative group delay (NGD) behavior of metamaterial. Through analyzing the GD of metamaterial equivalent circuit caused by poles and zeros, we design a novel NGD bandpass circuit. Furthermore, this thesis develops graphic method for group delay investigatiion and study the relationship between NGD, loss and gain in order to simplify the design of GD compensation circuit.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18297号 / 工博第3889号 / 新制||工||1597(附属図書館) / 31155 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 赤木 和夫, 教授 山子 茂, 教授 秋吉 一成 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

O Transtorno Bipolar (TB) é uma doença psiquiátrica grave, altamente incapacitante que está associada com diversas comorbidades médicas e altas taxas de suicídio. Embora sua fisiopatologia não esteja completamente elucidada, inúmeros estudos têm mostrado alterações no sistema imune de indivíduos com TB. A resposta crônica destes indivíduos ao estresse parece gerar um aumento da inflamação sistêmica bem como da neuroinflamação. A micróglia ativada devido aos estímulos inflamatórios contínuos deve ocasionar diferentes prejuízos tanto bioquímicos quanto funcionas. Os macrófagos, primeira linha de defesa, são células de característica plástica de extrema importância do sistema imune e podem ser estimulados a polarizar para diferentes formas com liberação de fatores pró e antiinflamatórios, estimulando ou mantendo a homeostase no ambiente agredido de alguma forma. Desta forma, nosso trabalho buscou investigar a resposta fenotípica dos macrófagos contra o meio ambiente pró-inflamatório sistêmico observado no plasma de pacientes bipolares eutímicos, maníacos e depressivos em comparação aos controles. A amostra incluiu 5 controles saudáveis, 8 pacientes bipolares remetidos, 5 pacientes maníacos e 5 pacientes depressivos. As citocinas e quimiocinas de RNAm em células U937 tratadas com plasma mostraram um padrão de expressão diferente relativo entre controles saudáveis e pacientes com TB. As citoquinas inflamatórias tais como IL-1β e TNF-α, em pacientes bipolares maníacos e depressivos demonstram maiores quantidades de IL-1β mRNA do que os pacientes eutímicos e pacientes depressivos induziram maiores quantidades de RNAm de TNF-α do que os pacientes eutímicos em células U937. Já a expressão das quimiocinas CXCL9 e CXCL10 no plasma de pacientes com TB depressivos, demostraram ser de menor expressão significativa no grupo de pacientes maníacos quando comparados a controles e pacientes bipolares eutímicos. Nossos resultados sugerem que as citocinas periféticas devem modular a polarização M1 ou M2 de macrófagos no TB. / Bipolar Disorder (BD) is a severe and highly incapacitating psychiatric disorder which is associated with the presence of medical comorbidities. The progression of BD is related to an important cognitive deficit and also to biological and clinical manifestations that lead to treatment resistance and worse prognosis. Immune disturbances have been widely observed and investigated in BD patients. Chronic inflammatory responses induce neuroinflammation, mainly by pro-inflammatory microglial activation, and result in biochemical and functional impairment. Macrophages are the first line of defense of the immune system and exhibit cell plasticity. As well, microglia represents the resident macrophage of the central nervous system been responsible for its protection. Both cells can be stimulated to polarize into two different phenotypes, mainly pro- and anti-inflammatory, maintaining the homeostasis under physiologic and pathologic conditions. Therefore, we aimed to investigate macrophages phenotypical response when submitted to BD patients plasma in different episodes, which is considered a pro-inflammatory environment, and healthy controls plasma. Subjects included healthy controls (n=5), remitted BD patients (n=8), manic patients (n=5) and depressive patients (n=5). The mRNA expression of chemokynes and cytokines from U937 cells treated with BD patients plasma were different from those submitted to healthy controls plasma. Higher mRNA expression of IL-1β was observed in those cells submitted to manic and depressive BD patients plasma when compared to euthymic patients. Also, depressive BD patients plasma induced higher expression of TNF-α compared to euthymic patients. However, chemokynes expression, such as CXCL9 and CXCL10, were reduced in depressive BD patients. However, chemokynes expression, such as CXCL9 and CXCL10, were reduced in depressive BD patients. Inflammatory cytokines such as IL-1β and TNF-α in bipolar manic and depressive patients demonstrate higher amounts of IL-1β mRNA that euthymic patients and depressive patients induced higher amounts of TNF-α mRNA levels than the patients in euthymic U937. Since the expression of CXCL9 and CXCL10 chemokines in plasma from patients with depressive TB, proved less significant expression in the group of manic patients when compared to controls and euthymic bipolar patients.

Retrievals of atmospheric information from satellite observations permit the investigation of otherwise inaccessible atmospheric phenomena. The recovery of this information from optical instrumentation located in orbit requires both an inversion algorithm like the Saskatchewan Multiplicative Algebraic Reconstruction Technique and a forward model like the SASKTRAN radiative transfer model. These are used together at the University of Saskatchewan to retrieve sulphate aerosol extinction profiles from the radiance measurements made by the Canadian built OSIRIS instrument. Although these retrievals are highly successful the process currently does not consider the polarization of light or OSIRIS's polarization sensitivities because SASKTRAN is a scalar model. In this work the development of a vector version of SASKTRAN that can perform polarized radiative transfer calculations is presented.<p> The vector SASKTRAN's results compare favorably with vector SCIATRAN, another polarized model that is in development at the University of Bremen. Comparisons of the stratospheric aerosol retrieval vectors generated from the scalar and vector SASKTRAN results indicate that the polarized calculations are an important factor in future work to improve the aerosol retrievals and to recover particle size or composition information.

Ultracold atomic gases have emerged as an ideal laboratory system to emulate many-body physics in an unprecedentedly controllable manner. Numerous many-body quantum states and phases have been experimentally explored and characterized using the ultracold atomic gases, offering new insights into many exciting physics ranging from condensed matters to cosmology. In this thesis, we will present a systematic numerical study of a novel experimental system, population imbalanced two-component ultracold Fermi gases. We explore the phase diagram of this system in both 3D and 1D especially focusing on the exotic Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase, which is characterized by a spatially oscillating order parameter. In 3D, we solve for the stationary states of trapped imbalanced Fermi gases in a wide range of parameter space with a home-made parallel eigen-solver for Bogoliubov-de Gennes (BdG) equations. Our results show that there exists a metastable state with a FFLO type oscillating order parameter. In 1D, we simulate the dynamical expansion of the population imbalanced Fermi gases from the trap. A numerically quasi-exact scheme, time-evolving block decimation (TEBD), is introduced for the comparative studies with the solution of the time-dependent BdG equation. Our results predict that the existence of FFLO states will leave conspicuous signatures in the density profiles during the expansion. For further understanding of the interplay between the population imbalance and two-body pairing interaction between two spin components, we also study the spin transport properties through trapped ultracold Fermi gases. The preliminary results will be discussed.

Las mol eculas metal-org anicas en la intercara con sustratos met alicos son sistemas interesantes para aplicaciones futuras en la grabaci on magn etica y dispositivos de espintr onica, ya que prometen sustituir algunos de los com- ponentes magn eticos basados en metales en uso hoy en d a. Las mol eculas que llevan esp n son materiales muy atractivos, tanto como capas nas bi- dimensionales en estructuras de multi-capas o como unidades magn eticas individuales, debido a sus reducidas dimensiones y propiedades funcionales. Entre esta clase de mol eculas, los imanes moleculares (SMMs) son los m as prometedores, ya que combinan propiedades magn eticas de bulk y dimensio- nes a escala molecular. Varios problemas limitan su aplicaci on en dispositivos reales: la principal es la baja temperatura de bloqueo TB, t picamente alrede- dor de la temperatura de liquefacci on de helio, por debajo del cu al los SMMs se comportan como nanoimanes; adem as, controlar el momento magn etico de una sola mol ecula no es una tarea f acil. Para superar estos obst aculos se est an investigando muchas estrategias y la m as prometedora parece ser la deposici on sobre sustratos magn eticos. Para el estudio de estos materiales, las espectroscop as de radiaci on sin- crotr on representan t ecnicas muy poderosas: la espectroscop a de absorci on de rayos X (XAS) y el dicro smo magn etico circular de rayos X (XMCD), en particular, permiten medir selectivamente diferentes elementos y medi- ciones independientes de los momentos at omicos orbitales y de esp n, can- tidades fundamentales para la comprensi on de las propiedades magn eticas macrosc opicas de la materia. En este estudio se ha investigado la interacci on del SMM TbPc2 con su- per cies ferromagn eticas (FM) de Ni. Usando la magnetometr a XMCD, se ha demostrado que TbPc2 se acopla antiferromagneticamente a la capa de Ni a trav es de la interacci on de supercanje mediada por el ligando. La ma- gnitud, pero no el signo, de la energ a de acoplamiento de canje puede ser ajustado mediante la reducci on o la oxidaci on del sustrato. Contrariamente a las mol eculas paramagn eticas, encontramos que el momento magn etico de los SMMs no sigue la magnetizaci on de la capa FM subyacente en cualquier con- dici on, sino que depende de la orientaci on relativa de los ejes de anisotrop a magn etica de la mol ecula y del sustrato, de la interacci on de supercanje y de la interacci on Zeeman. Las mol eculas de TbPc2, acopladas al Ni, conser- van sus propiedades intr nsecas de SMM, pero tambi en presentan una mejor estabilidad t ermica respecto a la mol ecula aislada, lo que demuestra una estrategia efectiva para incluir SMM en dispositivos de espintr onica. Se puede dar un paso m as hacia el control de un SMM estudiando el acoplamiento con sustratos antiferromagn eticos (AFM). Esto permitir a la inversi on de la magnetizaci on de capas moleculares con respecto al sustrato que bloquea el esp n. El fen omeno clave para demostrar este acoplamiento es el exchange bias, la anisotrop a magn etica unidireccional en la intercara entre capas FM y AFM, usada en espintr onica para estabilizar y controlar la magnetizaci on de estructuras multicapas. Aqu se investiga la posibilidad de inducir exchange bias entre SMM y capas AFM met alicas o de oxido. Las medidas de XMCD muestran que las mol eculas de TbPc2 depositadas sobre una capa na AFM de Mn tienen, despu es del enfriamiento con un campo magnetico externo aplicado, una curva de magnetizaci on abierta y despla- zada horizontalmente. Esta evidencia de exchange bias es coherente con la observaci on de esp nes bloqueados en la capa de Mn que se acoplan paralela- mente al momento magn etico del Tb, durante el enfriamiento en campo. Al contrario, las mol eculas depositadas sobre sustratos de CoO presentan ciclos de magnetizaci on paramagn eticos sin indicaci on alguna de exchange bias. Estos experimentos demuestran la capacidad de los SMMs para polarizar los esp nes bloqueados no compensados de un antiferromagneto y para formar heteroestructuras metal-org anicas que presentan exchange bias. Por ultimo, se ha puesto atenci on en la mol ecula paramagn etica MnPc. Se ha depositado esta mol ecula en varios sustratos, tanto magn eticos como no magn eticos, y se ha llevado a cabo un estudio sistem atico de la modi- caci on de la con guraci on electr onica en las diferentes muestras. Lo que observamos es que la con guraci on electr onica del MnPc se ve muy afecta- da por el sustrato y que el mecanismo principal que induce los cambios es probablemente la transferencia de carga. El MnPc en sustratos FM de Ni se comporta previsiblemente como las otras mol eculas paramagn eticas en capas FM, siguiendo la magnetizaci on del sustrato, mientras que, en capas AFM de oxido, no se observa exchange bias, como en el caso de SMM TbPc2. Tambi en hemos tratado de calcular el momento magn etico de cada muestra, descubriendo resultados inesperados que necesitan ser aclarados. Este estu- dio se encuentra todav a en una primera etapa, y necesita el apoyo de otras mediciones y c alculos teoric os para con rmar nuestras suposiciones. / Metal-organic molecules at the interface with metallic substrates are intere- sting systems for future applications in electronic and spintronic devices, as they hold promise for replacing some of the metal-based magnetic compo- nents in use today. Spin carrying molecules are highly attractive materials, both as ordered two-dimensional lms in multilayer structures and as single magnetic units, because of their reduced dimensions and functional proper- ties. Among this class of molecules, single molecule magnets (SMMs) are the most promising materials, because they combine bulk magnetic properties and molecular scale dimensions. Several problems limit their application in real devices; however the main one is the low blocking temperature (TB), tipically in the helium liquid range, under which SMMs behave like nanoma- gnets; furthermore, it is not an easy task to control the magnetic moment of a single molecule. To overcome these obstacles, many strategies are under investigation, including single molecules in break junctions, molecules depo- sition on magnetic substrates, change of the organic ligand to modify the ligand eld, etc.. To study these materials, synchrotron radiation spectroscopy represents a powerful technique: X-ray absorption spectroscopy (XAS) and x-ray magne- tic circular dichroism (XMCD), in particular, allow element selectivity and independent measurements of the atomic orbital and spin moments, funda- mentals quantities for understanding the macroscopic magnetic properties of the matter. We investigate the interaction of TbPc2 SMMs with ferromagnetic (FM) Ni surfaces. Using XMCD magnetometry, we show that TbPc2 couple anti- ferromagnetically to Ni lms through ligand-mediated superexchange. The magnitude, but not the sign of the exchange coupling energy, can be tailored by reducing or oxidizing the substrate. Contrary to paramagnetic molecules, we nd that the SMM magnetic moment does not follow the magnetization of the underlying FM layer, depending on the relative orientation of the mo- lecule and substrate magnetic anisotropy axes, superexchange, and Zeeman interaction. Coupled to Ni, TbPc2 retain their intrinsic SMM properties, but they exhibit enhanced thermal stability relative to isolated molecules, demonstrating an e ective approach to include SMM in spintronic devices. A further step towards the control of SMMs is to induce coupling with an antiferromagnetic (AFM) substrate. This nding may enable independent magnetization reversal of molecular layers with respect to the pinning sub- strate. The key phenomenon in this case is exchange bias, the unidirectional magnetic anisotropy at the interface between FM and AFM layers, used in spintronics to stabilize and control the magnetization of multilayer structures. Here we investigate the possibility to induce exchange bias between SMMs and metallic or oxide AFM layers. Element-resolved XMCD measure- ments show that TbPc2 molecules deposited on an AFM Mn thin lm present magnetic hysteresis and a negative horizontal shift of the Tb magnetization loop after eld cooling. This evidence of exchange bias is consistent with the observation of pinned spins in the Mn layer that couple parallel to the Tb magnetic moment during eld cooling. Conversely, molecules deposited on CoO substrates present paramagnetic magnetization loops with no indica- tion of exchange bias. These experiments demonstrate the ability of SMM to polarize the uncompensated pinned spins of an antiferromagnet and realize metal-organic exchange biased heterostructures. Finally, we draw attention to the behaviour of paramagnetic molecules, such as MnPc. We deposited MnPc on several substrates, both magnetic and non magnetic, and performed a systematic study of how the electronic con guration of the Mn ions and their magnetic moment are modi ed. What we observe is that the MnPc electronic con guration is highly a ected by the substrate and that the main mechanism inducing changes is likely charge transfer. MnPc on FM Ni behaves, as expected, like a normal paramagnetic molecule on FM layers, mimicking the substrate magnetization, while no exchange bias is observed on AFM oxides layers, as for TbPc2 SMM. We also tried to estimate the magnetic moment for each sample, nding unexpected results that need to be clari ed. This study is still at a rst stage, and needs the support of further measurements and calculations to con rm our assumptions.

Retrievals of atmospheric information from satellite observations permit the investigation of otherwise inaccessible atmospheric phenomena. The recovery of this information from optical instrumentation located in orbit requires both an inversion algorithm like the Saskatchewan Multiplicative Algebraic Reconstruction Technique and a forward model like the SASKTRAN radiative transfer model. These are used together at the University of Saskatchewan to retrieve sulphate aerosol extinction profiles from the radiance measurements made by the Canadian built OSIRIS instrument. Although these retrievals are highly successful the process currently does not consider the polarization of light or OSIRIS's polarization sensitivities because SASKTRAN is a scalar model. In this work the development of a vector version of SASKTRAN that can perform polarized radiative transfer calculations is presented.<p> The vector SASKTRAN's results compare favorably with vector SCIATRAN, another polarized model that is in development at the University of Bremen. Comparisons of the stratospheric aerosol retrieval vectors generated from the scalar and vector SASKTRAN results indicate that the polarized calculations are an important factor in future work to improve the aerosol retrievals and to recover particle size or composition information.