In this thesis, we investigate the transformation bandwidth and the thickness sensitivity of the anisotropic-slab linearly polarizes (LP) to circularly polarized (CP) polarizer. We define a transformation bandwidth and the thickness sensitivity based on the axial ratio. New methods are proposed that can eliminate the lengthy derivation and give deeper physical insight to the problem. Under the small reflection approximation, i.e., only the forward waves are considered, our methods can be applied to the design of the anisotropic-slab LP to CP polarizer. For the single anisotropic slab, the effect is represented graphically on the polarization ratio plane. It is shown that the polarization locus for a given axial ratio leads to a circle in the polarization state diagram. When combined with the graphical description of the change in the polarization state, the transformation bandwidth and the thickness sensitivity from an initial LP wave to a desired CP wave can be obtained easily. Furthermore, we present a method using the equivalent circuits to represent the polarization effect in anisotropic media, so that some concepts of the electric circuit can be applied. This method is more convenient in dealing with the polarization change when multiple anisotropic-slabs exist. The transformation bandwidths and the thickness sensitivities for the anisotropic-slab polarizer for several lossless media are studied. The results are discussed and illustrated.

Gemeinsamer Workshop von Universitaetsrechenzentrum und Professur "Rechnernetze und verteilte Systeme" der Fakultaet fuer Informatik der TU Chemnitz. Workshop-Thema: Mobilitaet Der Vortrag stellt das Common UNIX Printing System vor, das auf dem neuen Internet Printing Protokol Standard IPP beruht und diskutiert Einsatzmöglichkeiten im URZ der TU Chemnitz

Syftet med denna uppsats är att erhålla en fördjupad förståelse för de karaktäristiska drag som användare upplever att vinylskivan har i en tid av digitala strömningstjänster. Därför har två frågeställningar formulerats som behandlar vilka kvaliteter som användare tillskriver mediet och vilka praktiker som de upplever är relaterade till det. Det teoretiska ramverket som underbygger denna uppsats är främst Jay David Bolters och Richard Grusins (1999) remedieringsteori och tanken om att medier står i en dialektisk relation till varandra och att det gör att vi tillskriver dem olika kvaliteter. Tillkommer gör även, bland andra, John Durham Peters och Eric W. Rothenbuhlers (1997), Lee Marshalls (2014) och Steve Jones och Martin Sorgers (2011) teoretiserande av vinylskivan och tillhörande praktiker. Den metod som ligger till grund för studien är den kvalitativa forskningsintervjun. Tre intervjuer har genomförts med olika användare. I intervjuerna framkom det att användarna stakar ut vinylskivans kvaliteter genom att kontrastera den mot digitala medier. Bland dessa framkom att vinylskivan upplevs ha ett mer levande och intimt ljud och som tillsammans med det stora fysiska formatet erbjuder en audiovisuell upplevelse. Vinylskivan upplevs som ett helhetskoncept med en trippel historicitet som refererar till produktionsögonblicket, dess eget åldrande och dess föregående ägare. De praktiker som användarna upplever att vinylskivan bjuder in till var dels ett aktivt samlande och dels en njutningsfylld interaktion med grammofonen där själva medieringen bejakas.

Multiple lines of evidence suggest that elevated plasma lipoprotein(a) (Lp(a)) concentrations are a significant risk factor for the development of a number of vascular diseases including coronary heart disease and stroke. Lp(a) consists of a low-density lipoprotein (LDL)-like moiety and an unique glycoprotein, apolipoprotein(a) (apo(a)), that is covalently attached to the apolipoproteinB-100 (apoB-100) component of LDL by a single disulfide bond. Many studies have suggested a role for Lp(a) in the process of endothelial dysfunction. Indeed, Lp(a) has been shown to increase both the expression of adhesion molecules on endothelial cells (EC), as well as monocyte and leukocyte chemotactic activity in these cells. We have previously demonstrated that Lp(a), through its apo(a) moiety, increases actomyosin-driven EC contraction which, as a consequence, increases EC permeability. In this thesis, we have demonstrated a role for the strong lysine-binding site in the kringle IV type 10 domain of apo(a) in increasing EC permeability, which occurs through a Rho/Rho kinase-dependent pathway. We have further validated these findings using mouse mesenteric arteries in a pressure myograph system. We also have dissected another major signaling pathway initiated by apo(a) that involves in a disruption of adherens junctions in EC. In this pathway, apo(a)/Lp(a) activates the PI3K/Akt/GSK3β-dependent pathway to facilitate nuclear translocation of beta-catenin. In the nucleus beta-catenin induced the expression of cyclooxygenase-2 (COX-2) and the secretion of prostaglandin E2 (PGE2) from the EC. Finally, we have presented data to suggest a novel inflammatory role for apo(a) in which it induces the activation of nuclear factor-kappaB through promotion of the dissociation of IkappaB from the inactive cytoplasmic complex; this allows the nuclear translocation of NFkappaB with attendant effects on the transcription of pro-inflammatory genes. Taken together, our findings may facilitate the development of new drug targets for mitigating the harmful effects of Lp(a) on vascular EC which corresponds to an early step in the process of atherogenesis. / Thesis (Ph.D, Biochemistry) -- Queen's University, 2009-09-22 19:24:04.594

Three problems in compressive sensing, namely, recovery of sparse signals from noise-free measurements, recovery of sparse signals from noisy measurements, and recovery of so called block-sparse signals from noisy measurements, are investigated. In Chapter 2, the reconstruction of sparse signals from noise-free measurements is investigated and three algorithms are developed. The first and second algorithms minimize the approximate L0 and Lp pseudonorms, respectively, in the null space of the measurement matrix using a sequential quasi-Newton algorithm. An efficient line search based on Banach's fixed-point theorem is developed and applied in the second algorithm. The third algorithm minimizes the approximate Lp pseudonorm in the null space by using a sequential conjugate-gradient (CG) algorithm. Simulation results are presented which demonstrate that the proposed algorithms yield improved signal reconstruction performance relative to that of the iterative reweighted (IR), smoothed L0 (SL0), and L1-minimization based algorithms. They also require a reduced amount of computations relative to the IR and L1-minimization based algorithms. The Lp-minimization based algorithms require less computation than the SL0 algorithm. In Chapter 3, the reconstruction of sparse signals and images from noisy measurements is investigated. First, two algorithms for the reconstruction of signals are developed by minimizing an Lp-pseudonorm regularized squared error as the objective function using the sequential optimization procedure developed in Chapter 2. The first algorithm minimizes the objective function by taking steps along descent directions that are computed in the null space of the measurement matrix and its complement space. The second algorithm minimizes the objective function in the time domain by using a CG algorithm. Second, the well known total variation (TV) norm has been extended to a nonconvex version called the TVp pseudonorm and an algorithm for the reconstruction of images is developed that involves minimizing a TVp-pseudonorm regularized squared error using a sequential Fletcher-Reeves' CG algorithm. Simulation results are presented which demonstrate that the first two algorithms yield improved signal reconstruction performance relative to the IR, SL0, and L1-minimization based algorithms and require a reduced amount of computation relative to the IR and L1-minimization based algorithms. The TVp-minimization based algorithm yields improved image reconstruction performance and a reduced amount of computation relative to Romberg's algorithm. In Chapter 4, the reconstruction of so-called block-sparse signals is investigated. The L2/1 norm is extended to a nonconvex version, called the L2/p pseudonorm, and an algorithm based on the minimization of an L2/p-pseudonorm regularized squared error is developed. The minimization is carried out using a sequential Fletcher-Reeves' CG algorithm and the line search described in Chapter 2. A reweighting technique for the reduction of amount of computation and a method to use prior information about the locations of nonzero blocks for the improvement in signal reconstruction performance are also proposed. Simulation results are presented which demonstrate that the proposed algorithm yields improved reconstruction performance and requires a reduced amount of computation relative to the L2/1-minimization based, block orthogonal matching pursuit, IR, and L1-minimization based algorithms. / Graduate

The structure and geometry of subspaces of a given Banach space is among the most fundamental questions in Functional Analysis. In 1961, Kadec and Pelczyński pioneered a field of study by analyzing the structures of subspaces and basic sequences in L_p[0,1] under a naturally occurring restriction of p, 2 < p <\infty. They proved that any infinite-dimensional subspace X\subset L_p[0,1] for 2<p<\infty must either be isomorphic to l_2 and complemented in L_p or must contain a complemented subspace which is isomorphic to l_p. Many works since have studied the relationships between the sides of this dichotomy, chiefly by weakening hypotheses on side of the equation to gain stronger assumptions on the other. In this way, Johnson and Odell were able to show in 1974 that if X contains no further subspace which is isomorphic to l_2, then it must embed into l_p. Kalton and Werner further strengthened this result in 1993 by showing that such an embedding must be almost isometric. We start by analyzing the tools and definitions originally introduced in 1961 and define a natural extension to these methods. By analyzing this extension, we provide a constructive and streamlined reproving of Kalton and Werner's theorem: Let X be an infinite dimensional subspace of L_p[0,1] for 2<p<\infty. Then, either X contains a subspace which is isomorphic to l_2, or for every \varepsilon>\ 0, X embeds into l_p with constant 1 + \varepsilon.

No presente trabalho nóss provamos diversas desigualdades a respeito da convexidade uniforme e a suavidade uniforme para os espaços Lρ. Muitas dessas desigualdades são análogas a resultados já conhecidos. Posteriormente provamos várias desigualdades também envolvendo a convexidade uniforme e a suavidade uniforme para os espaços Cρ. Dentre estas desigualdades, provamos a desigualdade ótima 2-uniformemente convexa para os espaços Lρ e Cρ / In this work we prove several inequalities regarding the uniform convexity and the uniform smoothness of Lp spaces. Some of them are analogous to well-known results. We also prove several inequalities regarding the uniform convexity and the uniform smoothness of Cρ spaces. One of them is the optimal 2-uniform convexity inequality for Lρ and Cρp spaces.

Doctor en Ciencias de la Ingeniería, Mención Modelación Matemática / Esta tesis está dedicada al estudio del sistema de Boussinesq estacionario: \begin{subequations}\label{sum_sp:eqn_Boussinesq} \begin{equation} -\nu \Delta\vu +(\vu\cdot\nabla)\vu+\nabla \pi=\theta\vg \text{\quad en $\Omega$,}\qquad \div\;\vu=0 \text{\quad en $\Omega$,} \end{equation} \begin{equation} -\kappa \Delta\theta +\vu\cdot\nabla\theta=h \text{\quad en $\Omega$,} \end{equation} \end{subequations} donde $\Omega\subset\R{3}$ es un conjunto abierto, acotado y conexo; $\vu$, $\pi$ y $\theta$ representan el campo de velocidades, la presión y la temperatura del fluido, respectivamente, siendo éstas las incógnitas del sistema; $\nu>0$ es la viscosidad cinemática del fluido, $\kappa>0$ es la difusividad térmica del fluido, $\vg$ es la aceleración de la gravedad y $h$ es una fuente de calor aplicada al fluido. El objetivo de esta tesis es el estudio de la teoría $L^p$ para el sistema de Boussinesq estacionario considerando dos diferentes tipos de condiciones de frontera del campo de velocidades. En efecto, en una primera etapa, se considerará la condición de frontera de Dirichlet no homogéneo \begin{equation}\label{sum_sp:cond_Dirichlet_velocity} \vu=\vub\text{\quad sobre\quad}\Gamma, \end{equation} donde $\Gamma$ denota la frontera del dominio; mientras que en una segunda etapa, el campo de velocidades tendrá prescrito la condición de frontera de Navier no homogéneo \begin{equation}\label{sum_sp:cond_Navier_velocity} \vu\cdot\vn=0,\quad 2\left[\DT(\vu)\vn\right]_{\vt}+\alpha\;\vu_{\vt}=\bm{a},\text{\quad sobre\quad}\Gamma, \end{equation} donde $\DT(\vu)=\frac{1}{2}\left(\nabla\vu+(\nabla\vu)^T\right)$ es el tensor de deformación asociado con el campo de velocidades $\vu$, $\vn$ es el vector normal unitario exterior, $\vt$ es el correspondiente vector unitario tangente, $\alpha$ y $\vNb$ son una función de fricción y un campo vectorial tangencial definidas ambas sobre la frontera. Además, la condición de frontera para la temperatura será, en las dos primeras partes, la condición de frontera de Dirichlet no homogéneo \begin{equation}\label{sum_sp:cond_Dirichlet_temperature} \theta=\thb\text{\quad sobre\quad}\Gamma. \end{equation} Así, en primer lugar, estudiamos la existencia y unicidad de la solución débil para el problema \eqref{sum_sp:eqn_Boussinesq}, \eqref{sum_sp:cond_Dirichlet_velocity} y \eqref{sum_sp:cond_Dirichlet_temperature} en el caso hilbertiano. Además, la existencia de soluciones generalizadas para $p\geq\frac{3}{2}$ y soluciones fuertes para $1<p<\infty$ es probada. También, se estudiará la existencia y unicidad de la solución muy débil. Vale la pena señalar que debido a que la condición de Dirichlet no homogénea es considerada para la velocidad, el hecho de que la frontera del dominio pueda ser no conexa juega un papel importante, ya que aparece de manera explícita en las hipótesis de algunos de los principales resultados. Por otro lado, en la segunda etapa de la tesis, se estudiará la existencia de soluciones débiles en el caso de Hilbert, así como la existencia de soluciones generalizadas para $p>2$ y soluciones fuertes para $p\geq\frac{6}{5}$ para el problema \eqref{sum_sp:eqn_Boussinesq}, \eqref{sum_sp:cond_Navier_velocity} y \eqref{sum_sp:cond_Dirichlet_temperature}. Tenga en cuenta que la suposición hecha anteriormente acerca de la no conexidad de la frontera no aparecerá aquí debido a la restricción de impermeabilidad en la frontera. Finalmente, en la última parte de esta tesis, estudiamos la teoría $L^p$ para las ecuaciones de Stokes con la condición de Navier \eqref{sum_sp:cond_Navier_velocity}. Más precisamente, nos ocuparemos de la regularidad $W^{1,p}$ para $p\geq2$ y la regularidad $W^{2,p}$ para $p\geq\frac{6}{5}$.

No presente trabalho nóss provamos diversas desigualdades a respeito da convexidade uniforme e a suavidade uniforme para os espaços Lρ. Muitas dessas desigualdades são análogas a resultados já conhecidos. Posteriormente provamos várias desigualdades também envolvendo a convexidade uniforme e a suavidade uniforme para os espaços Cρ. Dentre estas desigualdades, provamos a desigualdade ótima 2-uniformemente convexa para os espaços Lρ e Cρ / In this work we prove several inequalities regarding the uniform convexity and the uniform smoothness of Lp spaces. Some of them are analogous to well-known results. We also prove several inequalities regarding the uniform convexity and the uniform smoothness of Cρ spaces. One of them is the optimal 2-uniform convexity inequality for Lρ and Cρp spaces.

No presente trabalho nóss provamos diversas desigualdades a respeito da convexidade uniforme e a suavidade uniforme para os espaços Lρ. Muitas dessas desigualdades são análogas a resultados já conhecidos. Posteriormente provamos várias desigualdades também envolvendo a convexidade uniforme e a suavidade uniforme para os espaços Cρ. Dentre estas desigualdades, provamos a desigualdade ótima 2-uniformemente convexa para os espaços Lρ e Cρ / In this work we prove several inequalities regarding the uniform convexity and the uniform smoothness of Lp spaces. Some of them are analogous to well-known results. We also prove several inequalities regarding the uniform convexity and the uniform smoothness of Cρ spaces. One of them is the optimal 2-uniform convexity inequality for Lρ and Cρp spaces.