Thesis (Ph. D.)--University of Virginia, 2008. / Includes bibliographical references. Also available online through Digital Dissertations.

Thesis (Ph. D.)--University of Nevada, Reno, 2002. / Includes bibliographical references. Online version available on the World Wide Web.

Thesis (Ph. D.)--University of Missouri--Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves [174]-186). Also available on the Internet.

Thesis (Ph.D.)--University of Nevada, Reno, 2002. / Includes bibliographical references. Online version available on the World Wide Web.

We propose a prototype model of market dynamics in which all functional relationships are linear. We take into account three borders, defined by linear functions, which are intrinsic to the economic reasoning: non-negativity of prices; downward rigidity of capacity (depreciation) and a capacity constraint for the production decision. Given the linear specification, the borders are the only source for the emerging of cyclical and more complex dynamics. In particular, we discuss centre bifurcations, border collision bifurcations and degenerate flip bifurcations - dynamic phenomena the occurrence of which are intimately related to the existence of borders. / Series: Department of Economics Working Paper Series

We explore the effects of Brexit on trade patterns and on the spatial distribution of industry between the United Kingdom and the European Union and within the EU. Our study adopts a new economic geography (NEG) perspective developing a linear model with three regions, the UK and two separated regions composing the EU. The 3-region framework and linear demands allow for different trade patterns. Two possible ante-Brexit situations are possible, depending on the interplay between local market size, local competition and trade costs: industrial agglomeration or dispersion. Considering a soft and a hard Brexit scenario, the ante-Brexit situation is altered substantially, depending on which scenario prevails. UK firms could move to the larger EU market, even in the peripheral region, reacting to the higher trade barriers, relocation representing a substitute for trade. Alternatively, some EU firms could move in the more isolated UK market finding shelter from the competition inside the EU. We also consider the post-Brexit scenario of deeper EU integration, leading to a weakening of trade links between the EU and the UK. Our analysis also reveals a highly complex bifurcation sequence leading to many instances of multistability, intricate basins of attraction and cyclical and chaotic dynamics. / Series: Department of Economics Working Paper Series

[pt] O presente trabalho analisa a transferência de calor e a perda de carga em escoamento turbulento através das regiões anulares lisas e aletadas. Os coeficientes de transferência de calor foram obtidos experimentalmente, utilizando-se a teoria de trocadores de calor. Também foram determinados os coeficientes de perda de carga associados a cada uma das geometrias analisadas. Os experimentos foram realizados em um trocador de calor bi-tubular concêntrico. Água (fluído quente) escoava através do tubo interno, enquanto ar (fluido frio) fluía através da região anular. Medindo-se as vazões e temperaturas na entrada e saída da seção de teste do trocador de calor, obtém-se a efetividade da mesma e, consequentemente, o coeficiente global de transferência de calor (médio). As condições de contorno adotadas foram de temperatura uniforme na superfície externa do tubo interno e de isolamento térmico na superfície externa do tubo interno e de isolamento térmico na superfície externa da região anular. Com o objetivo de obter-se condições de escoamento completamente desenvolvido, o trocador de calor possui um comprimento, a montante da seção de testes, de aproximadamente trinta diâmetros hidráulicos. Os coeficientes de transferência de calor e de perda de carga são apresentados de forma adimensional, como função do número de Reynolds do escoamento, os resultados obtidos para as regiões anulares lisas e aletadas são comparados entre si. O propósito de tal comparação foi o de estudar a influencia das aletas na perda de carga e na taxa de transferência de calor. No caso das regiões aletadas, verifica-se que a eficiência das aletas influencia a transferência de calor. Deste modo, realizou-se uma análise bi-dimensional de transferência de calor nas aletas para obter-se a eficiência das mesmas e, consequentemente, a eficiência das regiões aletadas. Também é mostrado que o desempenho térmico da região depende principalmente do número de Nusselt e da eficiência da mesma. Tais parâmetros são apresentados, em última análise, como funções do número de Reynolds e da geometria do problema. / [en] The present work is concerned with the turbulent heat transfer and pressure drop in smooth and finned annular ducts. Average heat transfer coeeficients have been obtained by means of the heat exchanger theory. In addition, friction factors have also been determined. The experiments were performed by utiling four double-pipe heat exchangers. The average heat transfer coefficients, for air flowing in the annular section, were fertmined by measuring the overall heat transfer coefficients of the heat exchangers. In order to aatain fully developed conditions, the heat exchangers had a starting length of 30 hydrualic diameters. The thermal boundary conditions consisted of uniform temperature on the inner surface, the outer surface being insulate. The heat transfer coefficients and friction factors are presented in dimensinless forms, as functions of the Reynolds number of the fow. The results for smooth and finned annular ducts were compared. The purpose of such comparison was to study the influence of the fins on the pressure drop and heat transfer rate. In the case of the finned annular ducts, it is shown that fin efficiency has some influence on the heat transfer rates. Then a two-dimensional heat transfer analysis was performed in order to obtain the fin efficiency and the annular region efficiency. It is also shown that the overall thermal performance of finned surfaces depends mainly of the Nusselt number and on the region efficiency. These parameters are presented as functiond of the Reynolds number of the flow and the geometry of the problem.

Partial differential equations are the chief means of providing mathematical models in science, engineering and other fields. Optimal control of partial differential equations (PDEs) has tremendous applications in engineering and science, such as shape optimization, image processing, fluid dynamics, and chemical processes. In this thesis, we develop and analyze several efficient numerical methods for the optimal control problems governed by elliptic PDE, parabolic PDE, and wave PDE, respectively. The thesis consists of six chapters. In Chapter 1, we briefly introduce a few motivating applications and summarize some theoretical and computational foundations of our following developed approaches. In Chapter 2, we establish a new multigrid algorithm to accelerate the semi-smooth Newton method that is applied to the first-order necessary optimality system arising from semi-linear control-constrained elliptic optimal control problems. Under suitable assumptions, the discretized Jacobian matrix is proved to have a uniformly bounded inverse with respect to mesh size. Different from current available approaches, a new strategy that leads to a robust multigrid solver is employed to define the coarse grid operator. Numerical simulations are provided to illustrate the efficiency of the proposed method, which shows to be computationally more efficient than the popular full approximation storage (FAS) multigrid method. In particular, our proposed approach achieves a mesh-independent convergence and its performance is highly robust with respect to the regularization parameter. In Chaper 3, we present a new second-order leapfrog finite difference scheme in time for solving the first-order necessary optimality system of the linear parabolic optimal control problems. The new leapfrog scheme is shown to be unconditionally stable and it provides a second-order accuracy, while the classical leapfrog scheme usually is well-known to be unstable. A mathematical proof for the convergence of the proposed scheme is provided under a suitable norm. Moreover, the proposed leapfrog scheme gives a favorable structure that leads to an effective implementation of a fast solver under the multigrid framework. Numerical examples show that the proposed scheme significantly outperforms the widely used second-order backward time differentiation approach, and the resultant fast solver demonstrates a mesh-independent convergence as well as a linear time complexity. In Chapter 4, we develop a new semi-smooth Newton multigrid algorithm for solving the discretized first-order necessary optimality system that characterizes the optimal solution of semi-linear parabolic PDE optimal control problems with control constraints. A new leapfrog discretization scheme in time associated with the standard five-point stencil in space is established to achieve a second-order accuracy. The convergence (or unconditional stability) of the proposed scheme is proved when time-periodic solutions are considered. Moreover, the derived well-structured discretized Jacobian matrices greatly facilitate the development of an effective smoother in our multigrid algorithm. Numerical simulations are provided to illustrate the effectiveness of the proposed method, which validates the second-order accuracy in solution approximations as well as the optimal linear complexity of computing time. In Chapter 5, we offer a new implicit finite difference scheme in time for solving the first-order necessary optimality system arising in optimal control of wave equations. With a five-point central finite difference scheme in space, the full discretization is proved to be unconditionally convergent with a second-order accuracy, which is not restricted by the classical Courant-Friedrichs-Lewy (CFL) stability condition on the spatial and temporal step sizes. Moreover, based on its advantageous developed structure, an efficient preconditioned Krylov subspace method is provided and analyzed for solving the discretized sparse linear system. Numerical examples are presented to confirm our theoretical conclusions and demonstrate the promising performance of proposed preconditioned iterative solver. Finally, brief summaries and future research perspectives are given in Chapter 6.

Made available in DSpace on 2015-05-14T12:59:52Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 7372344 bytes, checksum: 1300f16a278dc5441d8295112a100645 (MD5) Previous issue date: 2013-07-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Many Annonaceae species are odoriferous due to the presence of essential oils and these have attracted great pharmacological interest because they have action on smooth muscle. Thus, we aimed to investigate a possible spasmolytic activity of essential oils of leaves from Xylopia langsdorfiana A. St.-Hil. & Tul. (XL-OE), Xylopia frutescens Aubl. (XF-OE) e Rollinia leptopetala R. E. Fries (RL-OE) species on rat aorta, rat uterus and guinea pig trachea and ileum, and so elucidate the action mechanism of the essential oil that to present the better spasmolytic effect in one of the tested organs. Isometric and isotonic contractions and cytosolic Ca2+ were measured. In preliminary pharmacological screening all essential oils presented a higher spasmolytic potency and efficacy on guinea pig ileum, when compared with the other organs, being RL-OE the most promising natural product. So we decided to characterize the action mechanism of RL-OE on this organ. RL-OE inhibited cumulative concentration-response curves to histamine, and these were shifted to the right, in a non-parallel manner, with Emax reduction, discarding thus a competitive type antagonism and relaxed the guinea pig ileum contracted by KCl (40 mM), CCh (10-6 M) or histamine (10-6 M). How the common pathway of signaling of these contractile agents are the voltage-gated Ca2+ channels (CaV), we hypothesized that RL-OE would be preventing the Ca2+ influx through CaV. it was observed that RL-OE antagonized the CaCl2- induced contractions in a depolarizing medium namely without Ca2+, in addition to relax guinea pig ileum pre-contracted by S-(-)-Bay K 8644, a CaV-L selective agonist, demonstrating that the CaV subtype involved is CaV-L. How the relaxant potency of RL-OE was higher when the organ was pre-contracted by KCl this is suggestive that other mechanism would be involved on RL-OE spasmolytic effect. Since the CaV can be modulated by K+ channels, we decided to investigate these channels. The RL-OE spasmolytic action seems to involve the positive activation/modulation of valtege-gated (KV) and large conductance calcium-activated (BKCa) K+ channels, since there was a right-shift of RL-OE relaxation curve in the presence of the following blockers: 4-aminopyridine (4-AP), selective to KV; tetraethylammonium (TEA+) 1 mM and IbTX, selectives to BKCa. The confirmation of KV and BKCa participation was carried out by a simultaneous blockade (TEA+ and 4-AP) and verified since the relaxant potency was similar when in the presence of non-selective blocker (CsCl). In cellular experiments, the viability of longitudinal layer myocytes from guinea pig ileum was not altered in RL-OE (81 μg/mL) presence and the fluorescence intensity in these intestinal myocytes stimulated by histamine was reduced due to cytosolic Ca2+ concentration ([Ca2+]c). Thus the mechanism of action spasmolytic of RL-OE on guinea pig ileum involves blocking the Ca2+ influx, by CaV, in addition to positive activation/modulation of KV and BKCa, that would lead to reduced of [Ca2+]c and consequent relaxation of this organ. / Muitas espécies de Annonaceae são odoríferas, devido à presença de óleos essenciais e estes têm despertado um grande interesse farmacológico por apresentarem atividade sobre a musculatura lisa. Assim, decidiu-se investigar a possível atividade espasmolítica dos óleos essenciais das folhas das espécies Xylopia langsdorfiana A. St.-Hil. & Tul. (XL-OE), Xylopia frutescens Aubl. (XF-OE) e Rollinia leptopetala R. E. Fries (RL-OE) em aorta de rato, útero rata, traqueia e íleo de cobaia, além de elucidar o mecanismo de ação do óleo essencial que apresentasse uma melhor atividade espasmolítica em um dos órgãos testados. Foram realizadas medidas de contrações isotônicas e isométricas e do cálcio citosólico. Na triagem farmacológica preliminar todos os óleos essenciais apresentam maior eficácia e potência espasmolítica em íleo de cobaia, quando comparados aos outros órgãos, sendo o RL-OE o produto natural mais promissor. Assim, passou-se a caracterizar o mecanismo de ação do RL-OE nesse órgão. O RL-OE inibiu as curvas cumulativas à histamina, desviando-as para direita, de maneira não paralela e com redução do Emax, descartando um antagonismo do tipo competitivo, além de relaxar o íleo pré-contraído por KCl (40 mM), carbacol (10-6 M) ou histamina (10-6 M). Como o passo comum na via de sinalização destes agentes contráteis são os canais de Ca2+ dependentes de voltagem (CaV), hipotetizou-se que o RL-OE estaria impedindo o influxo de Ca2+ através destes canais. Foi observado que o RL-OE antagonizou as contrações induzidas por CaCl2 em meio despolarizante nominalmente sem Ca2+, além de relaxar o íleo pré-contraído por S-(-)-Bay K 8644, um agonista dos CaV-L, demonstrando que o subtipo de CaV envolvido é o CaV-L. Como a potência relaxante do RL-OE foi maior quando o órgão foi pré-contraído com KCl do que pelo S-(-)-Bay K8644 é sugestivo de que outros mecanismos estão envolvidos no efeito espasmolítico do RL-OE. Sabendo que os CaV podem ser modulados pelos canais de K+, decidiu-se investigar a participação desses canais. A ação espasmolítica do RL-OE parece envolver ativação/modulação positiva dos canais de K+ dependentes de voltagem (KV) e dos ativados por Ca2+ de grande condutância (BKCa), uma vez que houve desvio da curva de relaxamento do RL-OE para direita na presença dos bloqueadores: 4-aminopiridina (4-AP), seletivo para os KV; tetraetilamônio (TEA+) 1 mM e iberiotoxina, seletivos para os BKCa. A confirmação da participação dos KV e BKCa foi feita através do bloqueio simultâneo (TEA+ e 4-AP) e constatada, uma vez que, a potência relaxante foi similiar quando o bloqueio era realizado por um bloqueador não seletivo dos canais de K+ (CsCl). Nos experimentos celulares, a viabilidade dos miócitos da camada longitudinal do íleo de cobaia não foi alterada na presença do RL-OE (81 μg/mL) e a intensidade de fluorescência nos miócitos intestinais estimulados por histamina foi reduzida em consequência da redução da concentração citosólica de Ca2+ ([Ca2+]c). Assim, o mecanismo de ação espasmolítico do RL-OE em íleo de cobaia envolve bloqueio do influxo de Ca2+, via CaV, além da ativação/modulação positiva dos KV e BKCa, o que levaria a redução da [Ca2+]c e, consequente, relaxamento desse órgão.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2018-07-09T11:18:39Z No. of bitstreams: 2 Dissertação - Marco Túlio Lacerda Ribeiro - 2018.pdf: 1380967 bytes, checksum: 194ed48e2af9c60ef94be3f60db75ef7 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-07-09T11:27:43Z (GMT) No. of bitstreams: 2 Dissertação - Marco Túlio Lacerda Ribeiro - 2018.pdf: 1380967 bytes, checksum: 194ed48e2af9c60ef94be3f60db75ef7 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-07-09T11:27:43Z (GMT). No. of bitstreams: 2 Dissertação - Marco Túlio Lacerda Ribeiro - 2018.pdf: 1380967 bytes, checksum: 194ed48e2af9c60ef94be3f60db75ef7 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-06-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Background: Some studies relate the use of paracetamol with the exacerbation of asthma symptoms and other respiratory problems. Other studies are inconclusive or deny this correlation. This makes the association between paracetamol and airway hypersensitivity very controversial and still under debate. Objectives: To investigate the effect of chronic treatment with paracetamol on rats on the contraction and relaxation of isolated airways. Methods: Wistar rats were divided into 2 groups (n = 5-8). One group was treated for 2 weeks with paracetamol (400 mg / kg, v.o.) in drinking water and another control group (pure water). The animals were euthanized after two weeks, blood was collected for biochemical analyzes (ALT, AST, TBARs reaction) and tracheal rings were isolated and prepared in an organ bath to measure the isometric tension against contractile stimuli (concentration- effect for carbachol and KCl, concentration- 2+ effect curve for Ca stimulated with carbachol or KCl) and relaxants (isoprenaline, sodium nitroprusside and verapamil). Results: Liver enzymes ALT, AST and lipid peroxidation (TBARs) were significantly increased after paracetamol treatment. Acupuncture of the airway tracheal smooth muscle response does not present any alteration, either to the contractile or relaxing stimulus, for example: cholinergic agonist, membrane 2+ 2+ 2+ depolarization, Ca influx by the sarcolemma, internal release of Ca from the sarcoplasmic reticulum, Ca , β-receptor agonist or NO donor-induced relaxation. Conclusion: Chronic treatment with paracetamol does not induce hyper or hyporeativity of the airways isolated from rats. / Introdução: Alguns estudos relacionam o uso de paracetamol com a exacerbação dos sintomas da asma e outros problemas respiratórios. Outros estudos não são conclusivos ou negam essa correlação. Isso torna a associação entre o paracetamol e a hipersensibilidade das vias aéreas muito controversa e ainda em debate. Objetivos: Investigar o efeito do tratamento crônico com paracetamol em ratos sobre a contração e relaxamento de vias aéreas isoladas. Métodos: Ratos Wistar foram divididos em 2 grupos (n=5-8). Um grupo foi tratado por 2 semanas com paracetamol (400 mg/Kg, v.o.) na água de beber e outro, o grupo controle, foi tratado apenas com água potável. Os animais foram eutanasiados após duas semanas, o sangue foi coletado para análises bioquímicas (ALT, AST, reação de TBARs) e os aneis de traqueias foram isolados e preparados em banho de órgãos para medir a tensão isométrica mediante estímulos contráteis 2+ (curva concentração-efeito para carbacol e KCl; curva concentração-efeito para Ca estimulados com carbacol ou KCl) e relaxantes (isoprenalina, nitroprussiato de sódio e verapamil). Resultados: As enzimas hepáticas ALT, AST e a peroxidação lipídica (TBARs) foram significativamente aumentadas após o tratamento com paracetamol. A capacidade de resposta do músculo liso traqueal das vias aéreas não apresentam qualquer alteração, seja ao estímulo contrátil ou relaxante, como exemplo: agonista 2+ 2+ colinérgico, despolarização da membrana, influxo de Ca pelo sarcolema, liberação interna de Ca do 2+ retículo sarcoplásmico, bloqueio do canal Ca , agonista de receptores β ou relaxamento induzido por doador de NO. Conclusão: O tratamento crônico com paracetamol não induz a hiper ou hiporreatividade das vias aéreas isoladas de ratos.