9,154 research outputs found

    Enhancing Coexistence in the Unlicensed Band with Massive MIMO

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    We consider cellular base stations (BSs) equipped with a large number of antennas and operating in the unlicensed band. We denote such system as massive MIMO unlicensed (mMIMO-U). We design the key procedures required to guarantee coexistence between a cellular BS and nearby Wi-Fi devices. These include: neighboring Wi-Fi channel covariance estimation, allocation of spatial degrees of freedom for interference suppression, and enhanced channel sensing and data transmission phases. We evaluate the performance of the so-designed mMIMO-U, showing that it allows simultaneous cellular and Wi-Fi transmissions by keeping their mutual interference below the regulatory threshold. The same is not true for conventional listen-before-talk (LBT) operations. As a result, mMIMO-U boosts the aggregate cellular-plus-Wi-Fi data rate in the unlicensed band with respect to conventional LBT, exhibiting increasing gains as the number of BS antennas grows.Comment: To appear in Proc. IEEE ICC 201

    Carbon materials as template for the preparation of mixed oxides with controlled morphology

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    Resumen del libro de actas del Congreso: 5th Czech-Italian-Spanish Conference on Molecular Sieves and Catalysis, celebrado en Segovia del 16 al 19 de junio de 2013Bulk mixed oxide catalysts are widely used for many applications, such as catalysts for selective oxidation processes, electrocatalysts for fuel cells, gas sensors, and solid oxide electrolysers for the production of hydrogen. VPO (vanadium and phosphorous oxides) are one of the bulk mixed oxide materials which are of interest nowadays since they are active catalysts for saturated hydrocarbon activation. With the conventional synthesis procedures for preparing bulk mixed oxides is really difficult to control the morphology and the porous structure of these materials. In practice, there are just a few works about the synthesis of mixed oxide materials with controlled morphology. The aim of this work was to describe new approaches for the preparation of VPO mixed oxides materials with spherical morphology. A carbon material was prepared using cellulose as starting material by hydrothermal treatment with phosphoric acid at 200ºC and carbonized at 500ºC. SEM analysis showed that carbon spheres with diameter up to 0.5 m were prepared by this procedure. These phosphorous containing carbon material was impregnated with the appropriate amount of vanadium oxide species in order to obtain a monolayer of VOx species on the surface of the carbon materials following a procedure described previously (1). By this manner, a carbon supported VOx material with spherical morphology was obtained (VPO/Csph). The calcination of this material was optimized in order to obtain VPO spheres with diameter up to 1-2 m and with BET area values close to 100 m2/g. Figure 1 shows a SEM image of this sample (VPOsph). The presence of vanadium pyrophosphate phase, which has been described as the active phase of this catalytic system, was identified by XRD and Raman spectroscopy. Thus, the chemical composition as well as the morphology and porous structure of these new spherical materials makes them quite promising as catalysts

    Activated carbons as catalytic support for Cu nanoparticles

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    There are a wide range of catalytic applications for Cu-based nanoparticles materials, since Cu is an abundant and inexpensive metal and Cu nanoparticles possess unusual electrical, thermal and optical properties. The possible modification of the chemical and physical properties of these nanoparticles using different synthetic strategies and conditions and/or via postsynthetic chemical treatments has been largely responsible for the rapid growth of interest in these nanomaterials and their applications in catalysis. A previous work have explored the possibilities of SBA-15 (1,2) as support for Cu nanoparticles. In the present contribution, those results will be compared with the use of a carbon material as support, since activated carbon present many advantages with respect SBA, as the high surface area.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    The coevolution of plants and viruses: Resistance and pathogenicity

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    Virus infection may damage the plant, and plant defenses are effective against viruses; thus, it is currently assumed that plants and viruses coevolve. However, and despite huge advances in understanding the mechanisms of pathogenicity and virulence in viruses and the mechanisms of virus resistance in plants, evidence in support of this hypothesis is surprisingly scant, and refers almost only to the virus partner. Most evidence for coevolution derives from the study of highly virulent viruses in agricultural systems, in which humans manipulate host genetic structure, what determines genetic changes in the virus population. Studies have focused on virus responses to qualitative resistance, either dominant or recessive but, even within this restricted scenario, population genetic analyses of pathogenicity and resistance factors are still scarce. Analyses of quantitative resistance or tolerance, which could be relevant for plant–virus coevolution, lag far behind. A major limitation is the lack of information on systems in which the host might evolve in response to virus infection, that is, wild hosts in natural ecosystems. It is presently unknown if, or under which circumstances, viruses do exert a selection pressure on wild plants, if qualitative resistance is a major defense strategy to viruses in nature, or even if characterized genes determining qualitative resistance to viruses did indeed evolve in response to virus infection. Here, we review evidence supporting plant–virus coevolution and point to areas in need of attention to understand the role of viruses in plant ecosystem dynamics, and the factors that determine virus emergence in crops

    El caballo de bronce de Cancho Roano

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    Este trabajo da a conocer una pieza excepcional hallada en Cancho Roano durante la campaña de excavación de 1990. Se trata de un caballo de bronce de pequeño tamaño y muy buena factura, que quizá formó parte de un carrito votivo. Formaba parte de un deposito votivo de la estancia w-2, una de las habitaciones contiguas al edificio principal

    La paz de la mano de los derechos humanos

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    La primera etapa de la vida, la infancia, es un momento crucial para que los niños empiecen a establecer diferencias con sus compañeros, y comprendan que aunque todos viven en un mismo entorno, siempre existirán desemejanzas de muchas clases, sean estas raciales, religiosas, económicas o de cualquier otro tipo. Conociéndolas bien se promueve el respeto hacia las mismas y se fomenta una cultura de paz. Sabiendo esto los investigadores tomaron una población representativa de 18 estudiantes de tercer grado con edades que oscilan entre los ocho y diez años para el desarrollo de su proyecto. El proyecto que se presentará a continuación originado en la Universidad Cooperativa de Colombia y que tiene de objetivo general ‘’Orientar la relación que tiene El Proceso de Paz y los Derechos Humanos a niños de tercero primaria del Colegio Integrado Nuevo Mundo de Floridablanca, Santander’’ informa los resultados obtenidos en la investigación de tipo cualitativa etnográfica y trabajo de campo realizado en la institución educativa mencionada, donde además de orientar a los niños de tercero primara mediante diferentes tipos de actividades, las relaciones de El Tratado de Paz y los DD.HH, se espera que su conocimiento ayude a forjar una mejor sociedad en el futuro próximo.The first stage of life, childhood, is a crucial moment for children to begin establishing differences with their peers, and understand that although all the people live in the same environment, there will always be dissimilarities of many kinds, racial ones, religious, economic or of any other type. Knowing those differences, it promotes respect for them and fosters a culture of peace. Knowing this, the researchers took a representative population of 18, third-grade students aged between eight and ten years for the development of their project. The project that will be presented below originated at ‘’Universidad Cooperativa de Colombia’’ and its general objective says "To orient the relationship between the Peace Process and Human Rights to third grade students of ‘’Colegio Integrado Nuevo Mundo Floridablanca, Santander" 'reports the results obtained in ethnographic qualitative research and also the fieldwork carried out in the aforementioned educational institution, in addition to guiding the children of third priority through different types of activities, the relations of the Colombian Treaty of Peace and DD. HH, and knowing this, it expects to help to forge a better society in the close future.Resumen. -- 1.1 Situación problema. -- 1.2 Problema de investigación. -- 1.3 Objetivo general. -- 1.4 Objetivos específicos. -- 1.5 Justificación. -- 2. Marco Teórico. -- 2.1 Estado de Arte. -- 2.1.1 Nivel Local. -- 2.1.2 Nivel Nacional. -- 2.1.3 Nivel Internacional. -- 2.2 Marco Histórico. -- 2.2.1 Derechos Humanos. -- 2.2.1.1 Línea del tiempo de los DD.HH. -- 2.2.1.2 Procesos de paz en el mundo. -- 2.2.1.3 Cronología de los tratados de paz en Colombia. -- 2.3 Marco Legal. -- 2.3.1 Tratado de Paz Gobierno Colombiano y Guerrilla de las FARC. -- 2.3.1.1 Decretos de los puntos correspondientes al Tratado de Paz. -- 2.3.2 ‘’Fast Track’’. -- 2.3.3 DD.HH. -- 2.3.4 Mecanismos de protección de los Derechos Humanos en Colombia. -- 2.3.4.1 El Habeas Corpus. -- 2.3.4.2 Habeas Data. -- 2.3.4.3 Derecho de petición. -- 2.3.4.4 La acción de tutela. -- 2.3.4.5 Acción de cumplimiento. -- 2.3.4.6 Acción popular. -- 2.4. Marco Conceptual. -- 2.4.1 Punto 1 del tratado de paz: Reforma rural integral. -- 2.4.2 Punto 2 del Tratado de Paz: Participación política. -- 2.4.3 Punto 3 del Tratado de Paz: Fin del Conflicto. -- 2.4.4 Punto 4 del Tratado de Paz: Solución al Problema de las Drogas Ilícitas. -- 2.4.5 Punto 5 del Tratado de Paz: Reparación de víctimas: sistema integral de verdad, justicia, reparación y no repetición. -- 2.4.6 Punto 6 del Tratado de Paz: implementación, verificación y refrendación. -- 2.4.7 Contextualización de los DD.HH en Colombia. -- 2.5. Marco Contextual. -- 2.6 Importancia del proyecto en la Institución. -- 3.0 Metodología. -- 3.1 Tipo de Investigación. -- 3.2 Población y muestra. -- 3.3 Instrumentos de Investigación. -- 4. Análisis de resultados. -- 4.1Tabulación prueba diagnóstica. -- 4.2 Primera sesión: Punto 1 tratado de paz “Reforma rural integral”. -- 4.3 Segunda sesión: Punto 2 ‘’Participación Política’’. -- 4.4 Tercera sesión: Punto 3 ‘’Fin Del Conflicto”. -- 4.5 Tercera sesión: Punto 4 ‘’Solución al problema de las droga ilícitas’’. -- 4.6. Taller 5: Reparación de victimas. -- 4.7 Taller 6: Implementación, verificación y refrendación. -- 5. Conclusiones. -- 6. Propuesta. -- 6.1 Cartilla La paz de la mano de los Derechos Humanos. -- 6.1.2 Objetivos de La Paz de la Mano de los DD.HH. -- 6.1.3 Estructuración de la cartilla. -- 6.1.3.1 Prueba diagnostica. -- 6.1.3.2 Sesión 2. -- 6.1.3.3 Sesión 3. -- 6.1.3.4 Sesión 4. -- 6.1.3.5 Sesión 5. -- 6.1.3.6 Sesión 6. – Bibliografía
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