Strong boundedness and algebraically closed groups

summary:Let $G$ be a non-trivial algebraically closed group and $X$ be a subset of $G$ generating $G$ in infinitely many steps. We give a construction of a binary tree associated with $(G,X)$. Using this we show that if $G$ is $\omega_1$-existentially closed then it is strongly bounded

Discrete Wave Propagation In Quadratically Nonlinear Media

Discrete models are used in describing various microscopic phenomena in many branches of science, ranging from biology through chemistry to physics. Arrays of evanescently coupled, equally spaced, identical waveguides are prime examples of optical structures in which discrete dynamics can be easily observed and investigated. As a result of discretization, these structures exhibit unique diffraction properties with no analogy in continuous systems. Recently nonlinear discrete optics has attracted a growing interest, triggered by the observation of discrete solitons in AlGaAs waveguide arrays reported by Eisenberg et al. in 1998. So far, the following experiments involved systems with third order nonlinearities. In this work, an experimental investigation of discrete nonlinear wave propagation in a second order nonlinear medium is presented. This system deserves particular attention because the nonlinear process involves two or three components at different frequencies mutually locked by a quadratic nonlinearity, and new degrees of freedom enter the dynamical process. In the first part of dissertation, observation of the discrete Talbot effect is reported. In contrast to continuous systems, where Talbot self-imaging effect occurs irrespective of the pattern period, in discrete configurations this process is only possible for a specific set of periodicities. The major part of the dissertation is devoted to the investigation of soliton formation in lithium niobate waveguide arrays with a tunable cascaded quadratic nonlinearity. Soliton species with different topology (unstaggered all channels in-phase, and staggered neighboring channels with a pi relative phase difference) are identified in the same array. The stability of the discrete solitons and plane waves (modulational instability) are experimentally investigated. In the last part of the dissertation, a phase-insensitive, ultrafast, all-optical spatial switching and frequency conversion device based on quadratic waveguide array is demonstrated. Spatial routing and wavelength conversion of milliwatt signals is achieved without pulse distortions

Constitucionalidad de la ley de impuesto a las ganancias

En el presente trabajo se indaga acerca de la evolución histórica del Impuesto a las Ganancias en Argentina; abordar el tema señalado desde la perspectiva del derecho comparado a fin de darle una noción más global al lector sobre las diferencias y similitudes que hay con otros regímenes impositivos, en particular en los impuestos sobre la renta; siendo el objetivo principal y la problemática de nuestra investigación analizar la Ley de Impuesto a las Ganancias Nº 20.628 a efectos de establecer las posibles inconsistencias con respecto a la Constitución de la República Argentina.Fil: Esteban, Andrés Ezequiel. Universidad Nacional de Cuyo. Facultad de Ciencias Económicas. Delegación San Rafael.Fil: Iwanow, Raisa. Universidad Nacional de Cuyo. Facultad de Ciencias Económicas. Delegación San Rafael