When is U(X) a ring?

In this short paper, we will show that the space of real valued uniformly continuous functions defined on a metric space $(X,d)$ is a ring if and only if every subset $A\subset X$ has one of the following properties: $A$ is Bourbaki-bounded, i.e., every uniformly continuous function on $X$ is bounded on $A$. $A$ contains an infinite uniformly isolated subset, i.e., there exist $\delta>0$ and an infinite subset $F\subset A$ such that $d(a,x)\geq \delta$ for every $a\in F, x\in X$

Order isomorphisms between bases of topologies

In this paper we will study the representations of isomorphisms between bases of topological spaces. It turns out that the perfect setting for this study is that of regular open subsets of complete metric spaces, but we have achieved some results about arbitrary bases in complete metric spaces and also about regular open subsets of Hausdorff regular topological spaces

Enhancement of Millimeter-Band Transceivers with Gap Waveguide Technology

Mención Internacional en el título de doctorIt is known to all that year after year in modern society there is an urgent demand to consume wirelessly, and even stream ever larger multimedia content. High-frequency technologies have made it possible to go from transmitting analog voice and SMS text messages, to now transmitting live video in 4K quality from a mid-range smartphone. The way to measure these advances is by the bandwidth (Mb/s) reserved for each network user and the cost required to achieve it. To achieve even higher bandwidths, it is essential to improve signal coding techniques or increase the frequency of the signal, for example: to the mmWave bands (25GHz - 100 GHz), where these high-frequency techniques come into play. However, there is a frequency limit where current planar technology materials - such as the printed circuit boards used to build RF devices - are so lossy that they are not suitable at these mmWave frequencies. Current commercial solutions consist of guiding the electromagnetic energy with hollow metallic waveguides, but they suffer from the problem that as the frequency increases the diameter of these waveguides gets smaller and smaller, so manufacturing tolerances increase exorbitantly. Not to mention that they are usually manufactured in two parts, one upper and one lower, whose joints are not always perfect and produce energy losses. With these issues in mind, in 2009 the theory and basic science of a new electromagnetic energy guidance technology called Gap Waveguide was proposed, which is based on the use of metasurfaces constructed with periodic elements similar to a bed of nails. There are several implementations of this technology, but the three main ones are: Ridge, Groove and Inverted Microstrip Gap Waveguide. The latter is the most compatible with conventional planar manufacturing technologies and therefore the most cost-effective, although it also has drawbacks mainly in terms of losses when compared to the other versions. This thesis aims to deepen the study of the Inverted Microstrip guidance technology, its limitations and to develop with it some of the needed components in RF systems such as filters, diplexers, amplifiers, antennas, etc. Regarding the methodology for this thesis, a commercial simulation software for the analysis of antennas and components, CST Microwave Studio [1], has been used. AWR Microwave Office [2], a circuit simulator, has also been used to complement the simulations. On the other hand, there is a laboratory for the manufacture of prototypes in printed technology (with some limitations in terms of resolution) and the corresponding measurement laboratory, which includes network analyzers up to 40 GHz, spectrum analyzers and an anechoic chamber.This thesis arose under the Spanish Ministry of Science and Innovation (MINECO) and European Regional Development Fund (ERDF) project, called "Antenna for Mobile Satellite Communications (SATCOM) in Ka-Band by means of metasurfaces (2016-2019)", with reference TEC2016-79700-C2-2-R. Under this contract, the author signed an FPI research contract.Programa de Doctorado en Multimedia y Comunicaciones por la Universidad Carlos III de Madrid y la Universidad Rey Juan CarlosPresidente: Íñigo Cuiñas Gómez.- Secretario: Ángela María Coves Soler.- Vocal: Astrid Algaba Brazále

Dos representaciones, una misma Independencia: las vistas cinematográficas de los festejos de los Centenarios en México, 1910 y 1921. (Axe VI, Symposium 26)

En los meses de septiembre de 1910 y 1921, en los que se celebraron los Centenarios de inicio y consumación de la Independencia de México, los gobiernos en turno pusieron especial empeño en mostrar sus logros con la finalidad de consolidarse en el poder y ganar credibilidad, dos gobiernos que como parte de los Estados nacionales conmemoraban precisamente el nacimiento de México como nación, utilizaron diversos medios, entre ellos las artes y sus distintos soportes, incluyendo la entonces muy reciente cinematografía para dar una determinada imagen de nación y de la historia. Las investigaciones sobre los festejos de los Centenarios no son nuevas, sin embargo han tenido en los últimos años un importante resurgimiento. De ahí que nos parece viable explorar la construcción de los imaginarios en los dos Centenarios para intentar renovar la investigación relativa a los festejos desde el punto de vista del cine y contribuir a la reflexión sobre el llamado séptimo arte dentro del contexto de estas dos conmemoraciones. En el presente trabajo pretendemos considerar las películas filmadas durante los festejos de 1910 y 1921 como una especie de configuraciones simbólicas de los Centenarios, que contribuyeron a construir la trama simbólico-mítica que le dio sentido a dos proyectos de nación. Se pretende encontrar el discurso léxico-visual generado en el campo de poder cultural y político, que se evidenció a través de la creación de imágenes cinematográficas. Mas allá de revivir o rememorar las fiestas de los Centenarios en México, pretendemos hacer de ellas el punto de encuentro para revisar la construcción de las 2 imágenes cinematográficas de dos eventos fundacionales. El cine, en este caso las vistas cinematográficas, como espacio fílmico de representación, construye distintos imaginarios en cada una de las celebraciones, las imágenes presentadas dan cuenta de los cambios temáticos cuando se presenta a la nación