“Design and Development of Coplanar Strip Fed Planar Antennas”

With the recent progress and rapid increase in the field of communication, the designs of antennas for small mobile terminals with enhanced radiation characteristics are acquiring great importance. Compactness, efficiency, high data rate capacity etc. are the major criteria for the new generation antennas. The challenging task of the microwave scientists and engineers is to design a compact printed radiating structure having broadband behavior along with good efficiency and enhanced gain. Printed antenna technology has received popularity among antenna scientists after the introduction of planar transmission lines in mid-seventies. When we view the antenna through a transmission line concept, the mechanism behind any electromagnetic radiator is quite simple and interesting. Any electromagnetic system with a discontinuity is radiating electromagnetic energy. The size, shape and orientation of the discontinuities control the radiation characteristics of the system such as radiation pattern, gain, polarization etc. It can be either resonant or non-resonant. This thesis deals with antennas that are developed from a class of transmission lines known as coplanar strip-CPS, a planar analogy of parallel pair transmission line. The specialty of CPS is its symmetric structure compared to other transmission lines, which makes the antenna structures developed from CPS quite simple for design and fabrication. The structural modifications on either metallic strip of CPS results in different antennas. The first part of the thesis discusses a single band and dual band design derived from open ended slot lines which are very much suitable for 2.4 and 5.2 GHz WLAN applications. The second section of the study is vectored into the development of enhanced gain dipoles. A single band dipole and a wide band enhanced gain dipole suitable for 5.2/5.8 GHZ band and imaging applications are developed and discussed. Last part of the thesis discusses the development of directional UWBs. Three different types of ultra-compact UWBs are developed and almost all the frequency domain and time domain analysis of the structures are discussed.

Studies on scattering and thermodynamics of black holes in f(R) theory and Einstein's theory

One of the interesting consequences of Einstein's General Theory of Relativity is the black hole solutions. Until the observation made by Hawking in 1970s, it was believed that black holes are perfectly black. The General Theory of Relativity says that black holes are objects which absorb both matter and radiation crossing the event horizon. The event horizon is a surface through which even light is not able to escape. It acts as a one sided membrane that allows the passage of particles only in one direction i.e. towards the center of black holes. All the particles that are absorbed by black hole increases the mass of the black hole and thus the size of event horizon also increases. Hawking showed in 1970s that when applying quantum mechanical laws to black holes they are not perfectly black but they can emit radiation. Thus the black hole can have temperature known as Hawking temperature. In the thesis we have studied some aspects of black holes in f(R) theory of gravity and Einstein's General Theory of Relativity. The scattering of scalar field in this background space time studied in the first chapter shows that the extended black hole will scatter scalar waves and have a scattering cross section and applying tunneling mechanism we have obtained the Hawking temperature of this black hole. In the following chapter we have investigated the quasinormal properties of the extended black hole. We have studied the electromagnetic and scalar perturbations in this space-time and find that the black hole frequencies are complex and show exponential damping indicating the black hole is stable against the perturbations. In the present study we show that not only the black holes exist in modified gravities but also they have similar properties of black hole space times in General Theory of Relativity. 2 + 1 black holes or three dimensional black holes are simplified examples of more complicated four dimensional black holes. Thus these models of black holes are known as toy models of black holes in four dimensional black holes in General theory of Relativity. We have studied some properties of these types of black holes in Einstein model (General Theory of Relativity). A three dimensional black hole known as MSW is taken for our study. The thermodynamics and spectroscopy of MSW black hole are studied and obtained the area spectrum which is equispaced and different thermo dynamical properties are studied. The Dirac perturbation of this three dimensional black hole is studied and the resulting quasinormal spectrum of this three dimensional black hole is obtained. The different quasinormal frequencies are tabulated in tables and these values show an exponential damping of oscillations indicating the black hole is stable against the mass less Dirac perturbation. In General Theory of Relativity almost all solutions contain singularities. The cosmological solution and different black hole solutions of Einstein's field equation contain singularities. The regular black hole solutions are those which are solutions of Einstein's equation and have no singularity at the origin. These solutions possess event horizon but have no central singularity. Such a solution was first put forward by Bardeen. Hayward proposed a similar regular black hole solution. We have studied the thermodynamics and spectroscopy of Hay-ward regular black holes. We have also obtained the different thermodynamic properties and the area spectrum. The area spectrum is a function of the horizon radius. The entropy-heat capacity curve has a discontinuity at some value of entropy showing a phase transition.

Cambios en el régimen de pensiones en Colombia y su efecto en el margen intensivo de la oferta laboral

En Colombia, como en muchos países de América Latina, en los años 80 y 90 se hicieron cambios importantes en los regímenes de pensiones. Este trabajo hace un análisis de uno de esos cambios en Colombia. El cambio consistió en aumentar el tiempo de cotización necesario para reclamar los beneficios pensionales y la inclusión del salario dentro de la fórmula del monto de pensiones. Para este propósito se estudia el impacto sobre la oferta laboral de un cambio exógeno en estas condiciones usando un diseño de regresión discontinua. Se encuentra un efecto positivo sobre las horas promedio trabajadas en la semana.

Conflicto armado colombiano

El conflicto armado colombiano está lleno de enseñanzas para la resolución negociada de conflictos. En la medida en que ha sido una confrontación compleja y prolongada, los grupos armados se han convertido en protagonistas. Tanto sus objetivos como el uso de la violencia han generado controversias alrededor de cuáles deben ser las acciones o respuestas que se implementan para hacer frente a dichas situaciones. Al igual que en otros países, los actores involucrados han participado en numerosos acercamientos, diálogos políticos o procesos de paz, aportando experiencias de negociaciones que involucran a diferentes sectores de la sociedad civil, actores estatales, comunidad internacional y organizaciones multilaterales.En este sentido, resulta pertinente no sólo retomar el surgimiento, caracterización y posibles motivaciones de tres de los más grandes grupos al margen de la ley —paramilitares, ELN, FARC— que han participado en el conflicto, sino también explorar las formas de acercamiento a estos por parte del gobierno colombiano y sus diferentes administraciones, para así comprender la complejidad y las múltiples dimensiones desde las cuales se representan diversas visiones sobre la evolución del conflicto y los hechos de corta, mediana y larga duración, en tanto esto permite dilucidar las continuidades y discontinuidades que han dado paso a ver el fenómeno a través de causas culturales, complejos políticos o perspectivas económicas.-----The armed conflict in Colombia is full of lessons for negotiated conflict resolution. Insofar as this has been a complex and long-lasting confrontation, the armed groups have now become protagonists. Their objectives as much as their use of violence has generated controversy about which actions or responses should be implemented to face such situations. Similarly to other countries, the players concerned have participated in several rapprochements, political dialogues or peace processes by contributing experience in negotiations that involve different sectors of the civil society, state players, the international community, and multilateral organizations. To that effect, it is relevant not only to retake the emergence, characterization and possible motivations of three of the biggest groups outside the law –paramilitary, ELN, FARC– which have participated in the conflict, but also to explore the rapprochement methods the Colombian government and its different administrations have employed with these groups. This way, we can fully understand the complexity and the multiple dimensions in the representation of various views of the conflict evolution and the short, medium, and long-term events in as much as this allows clarification of the continuity and discontinuity that have resulted in seeing the phenomenon from the standpoint of cultural causes, political complexities or economic perspectives.

Cambio político y consolidación democrática en México. Los límites del modelo de las transiciones a la democracia

 Este texto plantea una reflexión sobre el estado actual de la democracia en México. Para ello se basa en una lectura crítica de las interpretaciones de la transición mexicana. Estas últimas subrayan el carácter sui generis e incompleto de dicha transición, cuya conclusión no ha significado una discontinuidad clara entre la etapa autoritaria y la de consolidación democrática. Nuestro planteamiento consiste en mostrar que los límites actuales de la democracia mexicana, en parte identificables como problemas de consolidación, dejan dudas sobre la llegada de la democracia a México. Lo ilustramos en torno a la pluralización aparente del sistema de partidos, a la cual los actores y estructuras autoritarias han sabido adaptarse, y en torno a la débil consolidación del Estado de derecho y las instituciones, amenazadas por la ascensión vertiginosa del crimen organizado. La combinación de las recomposiciones autoritarias y de esas nuevas amenazas no se reduce a meras herencias autoritarias, en un contexto supuestamente democrático, ni tampoco admite la hipótesis de una transición inconclusa. Implica más bien una huida hacia delante, la cual oscila entre la democracia y su negación, así como entre las herencias del pasado y un cambio mal asimilado, obligando a revisar el modelo de análisis de las transiciones a la democracia, parcialmente pertinente, pero demasiado lineal y reductor.-----This paper proposes a reflection on the current status of democracy in Mexico. For this purpose, it has been based on an analytical reading of interpretations to the Mexican transition. They highlight the sui generis and unfinished nature of such transition, whose completion has not entailed a clear discontinuity between the authoritarian phase and the democratic consolidation phase. Our approach consists in showing that the current limitations of Mexican democracy, which are in part identifiable as consolidation issues, leave doubts about the arrival of democracy to Mexico. This is illustrated around the supposed plurality of the party system, to which the actors and power structures have adapted, and around the weak consolidation of the constitutional state and the institutions, threatened by the dramatic escalation of organized crime. The combination of authoritarian recomposition and such new threats is not a mere authoritarian inheritance, in what is a supposed democratic context, nor does it agree with the hypothesis of an unconcluded transition. It rather implies fleeing forwards, which in itself oscillates between democracy and its denial as well as between past legacies and a badly assimilated change, thus forcing us to review the analytical model for transitions to democracy which is relevant in part, but far too linear and minimizing.

Ciclos político-económico-electorales y su incidencia en los niveles de pobreza en el marco de la competencia por el poder

El interés de la presente monografía es analizar los efectos de los ciclos político-económico-electorales (CPEE) sobre los niveles de pobreza en Colombia para el periodo del 2002 al 2010. Se analiza el manejo de la política fiscal por parte del gobierno con el fin de caracterizar el ciclo político entre oportunista o partidista. De esta forma, se pretende corroborar que en Colombia los CPEE generan efectos en la economía. No obstante, estos efectos pueden ser más o menos duraderos en función de la sostenibilidad del discurso ganador en la contienda electoral. Como resultado de este trabajo se determinó que la discontinuidad en el manejo de la política fiscal presenta un ciclo político-económico-electoral oportunista que contribuye negativamente los niveles de pobreza. Para desarrollar lo anterior, se realiza un análisis el cual se aborda desde el Enfoque de la Elección Racional.

Parametric pension reform and the intensive margin of labor supply, evidence from Colombia

We analyze the effect of a parametric reform of the fully-funded pension regime in Colombia on the intensive margin of the labor supply. We take advantage of a threshold defined by law in order to identify the causal effect using a regression discontinuity design. We find that a pension system that increases retirement age and the minimum weeks during which workers must contribute to claim pension benefits causes an increase of around 2 hours on the number of weekly worked hours; this corresponds to 4% of the average number of weekly worked hours or around 14% of a standard deviation of weekly worked hours. The effect is robust to different specifications, polynomial orders and sample sizes.

Do more decentralized local governments do better? an evaluation of the 2001 decentralization reform in Colombia

In this paper I evaluate the impact of the 2001 decentralization reform in Colombia. I use data from Colombia's municipalities. I look at the effect of the 2001 reform on enrolment in pre-college schools. While all municipalities received earnmarked national transfers, withthe reform some of then now have more responsabilities to provide education (deeper decen-tralization) than others. Particulary important, the reform entitle the more decentralizedmunicipalities to sign subsidy contracts with private school. Departments (the regional gov-ernments) are entitle to sign this type of contracts for the less decentralized municipalities.Since the rule for municipalities to receive more responsabilities follows and exogenous popu-lation threshold, I can implement Regression Discontinuity Design. Enrolment is measuredthrough two variables: the number of students enroled in public schools and the number of subsidized students enroled in private schools. Results sugest that more decentralized mu-nicipalities subsidize more students in private schools. The difference is significant at all thelevels of pre-college school for the period 2004-2006. In 2005, the difference accounts for20% of enrolment in private schools and 3% of population of school age. Besides, there are not significant differences among municipalities regarding enrolment in public schools.

Caracterización de la competencia entre dos organizaciones del sector de seguros en Colombia

En la permanente búsqueda de mejores condiciones que las organizaciones realizan con el propósito de dar respuesta a los cambios del entorno y la complejidad de la interacción con las organizaciones del mismo sector, se encuentra necesario identificar las características que les permiten a estas, sobrevivir, mantenerse en el mercado o crecer en él. En este orden de ideas, en este documento se desarrolla la caracterización de la forma como dos organizaciones importantes y líderes del sector asegurador en Colombia: Seguros Bolívar y Suramericana de Seguros, compiten, desde el punto de vista comercial, con el propósito de identificar como esto influye en cada organización. La investigación se centró en explicar a partir de los autores revisados y analizados con respecto al concepto de la competencia, en particular, la forma como se enfrenta la organización al entorno tanto interno como externo, la influencia de cada organización según su estructura, su importancia, la disponibilidad de los recursos necesarios para desarrollar sus actividades, el impacto y las implicaciones organizacionales a partir de la forma cómo se enfrenta el entorno. Para lo anterior y con base a la revisión conceptual, se realizó la recolección de datos y cifras tanto de las organizaciones como del sector al cual pertenecen, adicionalmente se realizaron entrevistas tanto estructuradas como semi estructuradas al área de ventas, debido a que es el área de las organizaciones encargada de generar estrategias de ventas, posicionar productos en el mercado, identificar el perfil del consumidor, conocer y comprender el mercado y la competencia. Lo anterior con el fin de caracterizar a las organizaciones analizadas, determinando cómo responden a la competencia y al entorno, para finalmente establecer cuáles son los comportamientos recurrentes, similares y diferentes entre ellas. Por lo tanto, los resultados obtenidos en la investigación permiten establecer si dos empresas con estructuras, tamaño y participación en el mercado similares compiten de igual forma y que implicación tiene esto en el comportamiento organizacional.

Informality in the City: a Theoretical Analysis

This thesis theoretically studies the relationship between the informal sector (both in the labor and the housing market) and the city structure.

Congress composition and electoral advantage

In 2003, an electoral reform changed the mechanism to assign seats in the Colombian Congress. I simulate the 2006 Senate elections using the previous assignment mechanism to determine which senators benefited from the reform, i.e. would have not been elected had the reform not been made. With the results of the simulation, I use a regression discontinuity design to compare the senators that would have been barely elected anyways with those who would have lost, but were near to be elected. I check the differences in the amount of law drafts presented, the attendance to voting sessions, and a discipline index for each senator as proxy of their legislative behavior. I find that the senators benefiting from the reform present a different legislative behavior during the 4-year term with respect to the senators that would have been elected anyways. Since the differential legislative behavior cannot be interpreted as being better (worse) politician, I examine if the behavioral difference gives them an electoral advantage. I find no difference in the electoral result of 2010 Senate election in terms of the probability of being (re)elected in 2010, the share of votes, the share of votes within their party list, and the concentration of their votes. Additionally, I check the probability of being investigated for links with paramilitary groups and I find no differences. The results suggest that political reforms can change the composition of governing or legislative bodies in terms of performance, but it does not necessarily translate into an electoral advantage.

La productividad de la morfología verbal a los años dos años de edad

Este trabajo se centra en estudiar la adquisición de la morfología verbal en una lengua con un paradigma verbal morfológicamente rico. Se predice que los niños de dos años no mostrarán productividad morfológica ante verbos desconocidos. La muestra se compone de 12 sujetos de edades comprendidas entre los 22 y los 31 meses. El procedimiento, de tipo experimental, se caracteriza por entrenar a los niños con verbos inventados. Los resultados muestran que los sujetos solamente utilizan los nuevos verbos con la forma morfológica con la que se han presentado. También se observa la omisión de determinados constituyentes de la oración. Estos resultados se discuten en relación con la asunción de discontinuidad de las competencias lingüísticas infantiles

Expectativas evolutivas, ideas y creencias sobre la educación infantil de familias y maestros: ¿continuidad o discontinuidad?

La perspectiva ecológica sobre el desarrollo humano (Bronfenbrenner, 1979) pone el acento en la relación entre los diferentes contextos de vida de los niños. En la educación infantil, los contextos de vida mas importantes son la familia y la escuela. En este artículo mostramos los aspectos de continuidad y discontinuidad entre ambos contextos en relación a las ideas de las familias y las educadoras sobre el desarrollo infantil y también a sus creencias y expectativas sobre la educación. Los resultados muestran que existe un acuerdo notable en muchos aspectos entre las familias y las educadoras, si bien también existen aspectos de desacuerdo, principalmente entre las educadoras de parvulario y las familias

A Tropospheric Assessment of the ERA-40, NCEP, and JRA-25 Global Reanalyses in the Polar Regions

The reliability of the global reanalyses in the polar regions is investigated. The overview stems from an April 2006 Scientific Committee on Antarctic Research (SCAR) workshop on the performance of global reanalyses in high latitudes held at the British Antarctic Survey. Overall, the skill is much higher in the Arctic than the Antarctic, where the reanalyses are only reliable in the summer months prior to the modern satellite era. In the Antarctic, large circulation differences between the reanalyses are found primarily before 1979, when vast quantities of satellite sounding data started to be assimilated. Specifically for ERA-40, this data discontinuity creates a marked jump in Antarctic snow accumulation, especially at high elevations. In the Arctic, the largest differences are related to the reanalyses depiction of clouds and their associated radiation impacts; ERA-40 captures the cloud variability much better than NCEP1 and JRA-25, but the ERA-40 and JRA-25 clouds are too optically thin for shortwave radiation. To further contrast the reanalyses skill, cyclone tracking results are presented. In the Southern Hemisphere, cyclonic activity is markedly different between the reanalyses, where there are few matched cyclones prior to 1979. In comparison, only some of the weaker cyclones are not matched in the Northern Hemisphere from 1958-2001, again indicating the superior skill in this hemisphere. Although this manuscript focuses on deficiencies in the reanalyses, it is important to note that they are a powerful tool for climate studies in both polar regions when used with a recognition of their limitations.

Unification of the probe and singular sources methods for the inverse boundary value problem by the no-response test

In this article, we use the no-response test idea, introduced in Luke and Potthast (2003) and Potthast (Preprint) and the inverse obstacle problem, to identify the interface of the discontinuity of the coefficient gamma of the equation del (.) gamma(x)del + c(x) with piecewise regular gamma and bounded function c(x). We use infinitely many Cauchy data as measurement and give a reconstructive method to localize the interface. We will base this multiwave version of the no-response test on two different proofs. The first one contains a pointwise estimate as used by the singular sources method. The second one is built on an energy (or an integral) estimate which is the basis of the probe method. As a conclusion of this, the probe and the singular sources methods are equivalent regarding their convergence and the no-response test can be seen as a unified framework for these methods. As a further contribution, we provide a formula to reconstruct the values of the jump of gamma(x), x is an element of partial derivative D at the boundary. A second consequence of this formula is that the blow-up rate of the indicator functions of the probe and singular sources methods at the interface is given by the order of the singularity of the fundamental solution.