Circular polarized 60 GHz antennas

Many multimedia applications for high speed data wireless transmissions (around Gb/s or multi-Gb/s) are used in indoor systems (<10m). Some examples of them are the Ethernet Gigabit (1.25 Gb/s), the wireless high-speed download and the wireless transfer of high-definition video (2-20Gb/s). These high transmission rates cannot be implemented in the traditional frequency bands dedicated for the typical wireless systems, since they obtain an important degradation of service and the bandwidth is not enough for the data rate. For this reason, the Federal Communications Commission (FCC) has introduced recently 7 GHz of bandwidth, without license, in the band of 60 GHz. It is mainly due to the appearance of the atmospheric attenuation (10 to 15 dB/Km), since the presence of the oxygen affects in a bandwidth of 8 GHz (approximately) over the 60 GHz band; So the band of 60 GHz is not suitable for long distances (more than 2 Km). However, it is possible to dedicate completely in indoor wireless applications (<50m), where the atmospheric attenuation does not have any significant impact. This high bandwidth allows high speeds of data transmission and a new range of ultrahigh rates of the wireless communications systems. In consequence, the wireless highdefinition multimedia interface (wHDMI) and "Kiosk-downloading" are some applications with a high volume of information. It is important to highlight that wHDMI will offer an important improvement in the WLAN incorporated in the systems of portable computer (laptops, PDAs, etc ...). On the other hand, " Kiosk-downloading " is a possible solution to transfer, in a short time, DVD's movies from a server (kiosk) to a portable device such as iPods or PDAs. For example, the download of 120 minutes of a DVD would take 10 minutes with a rate of 54 Mb / s, whereas with this new technology would only take 13 seconds for a 2 Gb / s rate, and for 6 Gb / s rate it would only takes 4 seconds. In spite of the quantity of publications and the interest related to the 60 GHz band, it is possible to observe that the data rates of WLAN and WPAN increase periodically. For example, in 1999 the standard 802.11.b was allowing a maximum speed of 11Mb/s and in 2007 the rate was coming until 300Mb/s through the support to the project 802.11.n. Therefore, in 2011 it is possible to anticipate that a rate of a few Gb/s will be offered. Therefore, in order to satisfy the increasing demand of bandwidth, many enterprises and research institutions are investigating in new technologies to solve or at least to cover it temporally. For example, in March, 2005, the Group of Tasks 3C (TG3c) in IEEE802.15 was formed to coordinate the normalization of the 60 GHz band [12]. In order to contribute something to this investigation topic, this project is dedicated to the study of different antennas capable of working at the 60 GHz band and with the addition value of being circular polarized

Tamaño corporal y composición de la fauna ibérica de Scarabaeoidea coprófagos (Insecta, Coleoptera)

Body size measurements have been used in a study of the composition of the iberic Scarabaeoidea coprophage fauna. Although the number of iberic species with relatively small body size is much greater, the majority of iberic genera are of a larger average body size. The number of world species of the iberic genera, and the proportion of species present in the Iberian Peninsula, is also a function of average body size. These facts seem to point to rates of speciation, extinction and evolutionary permanence being functions of the body size of the phyletic lines which constitute today's iberic Scarabaeoidea coprophage fauna.Se ha examinado la composición ibérica de 10s Scarabaeoidea coprófagos teniendo en cuenta el tamaño corporal. Aunque el número de especies ibéricas de menor tarnaíío relativo es mucho mayor, la mayoría de 10s géneros ibéricos tienen un tamaño corporal medio superior. El número de especies mundiales de 10s géneros ibéricos y la proporción de especies presentes en la península sobre el total, es también diferente según el tamaño corporal medio. Por todo ello, se estima probable que han debido de existir tasas de especiación, extinción y permanencia evolutiva diferentes, según el tamaño corporal de las líneas filéticas que constituyen la actual fauna ibérica de Scarabaeoidea coprófagos

More complex distribution models or more representative data?

Distribution models for species are increasingly used to summarize species’ geography in conservation analyses. These models use increasingly sophisticated modeling techniques, but often lack detailed examination of the quality of the biological occurrence data on which they are based. I analyze the results of the best comparative study of the performance of different modeling techniques, which used pseudo-absence data selected at random. I provide an example of variation in model accuracy depending on the type of absence information used, showing that good model predictions depend most critically on better biological data

Comentario bibliográfico

Comentario sobre la obra: G. HALFFTER, J. SOBERÓN, P. KOLEFF & A. MELIC (EDS.), 2005. Sobre Diversidad Biológica: El significado de las diversidades alfa, beta y gamma

Circular polarized 60 GHz antennas

Many multimedia applications for high speed data wireless transmissions (around Gb/s or multi-Gb/s) are used in indoor systems (<10m). Some examples of them are the Ethernet Gigabit (1.25 Gb/s), the wireless high-speed download and the wireless transfer of high-definition video (2-20Gb/s). These high transmission rates cannot be implemented in the traditional frequency bands dedicated for the typical wireless systems, since they obtain an important degradation of service and the bandwidth is not enough for the data rate. For this reason, the Federal Communications Commission (FCC) has introduced recently 7 GHz of bandwidth, without license, in the band of 60 GHz. It is mainly due to the appearance of the atmospheric attenuation (10 to 15 dB/Km), since the presence of the oxygen affects in a bandwidth of 8 GHz (approximately) over the 60 GHz band; So the band of 60 GHz is not suitable for long distances (more than 2 Km). However, it is possible to dedicate completely in indoor wireless applications (<50m), where the atmospheric attenuation does not have any significant impact. This high bandwidth allows high speeds of data transmission and a new range of ultrahigh rates of the wireless communications systems. In consequence, the wireless highdefinition multimedia interface (wHDMI) and "Kiosk-downloading" are some applications with a high volume of information. It is important to highlight that wHDMI will offer an important improvement in the WLAN incorporated in the systems of portable computer (laptops, PDAs, etc ...). On the other hand, " Kiosk-downloading " is a possible solution to transfer, in a short time, DVD's movies from a server (kiosk) to a portable device such as iPods or PDAs. For example, the download of 120 minutes of a DVD would take 10 minutes with a rate of 54 Mb / s, whereas with this new technology would only take 13 seconds for a 2 Gb / s rate, and for 6 Gb / s rate it would only takes 4 seconds. In spite of the quantity of publications and the interest related to the 60 GHz band, it is possible to observe that the data rates of WLAN and WPAN increase periodically. For example, in 1999 the standard 802.11.b was allowing a maximum speed of 11Mb/s and in 2007 the rate was coming until 300Mb/s through the support to the project 802.11.n. Therefore, in 2011 it is possible to anticipate that a rate of a few Gb/s will be offered. Therefore, in order to satisfy the increasing demand of bandwidth, many enterprises and research institutions are investigating in new technologies to solve or at least to cover it temporally. For example, in March, 2005, the Group of Tasks 3C (TG3c) in IEEE802.15 was formed to coordinate the normalization of the 60 GHz band [12]. In order to contribute something to this investigation topic, this project is dedicated to the study of different antennas capable of working at the 60 GHz band and with the addition value of being circular polarized

Evaluation of the potential of translocated common cockle for ecological risk assessment studies: bioaccumulation and biomarkers test

Thesis submitted to the Faculdade de Ciências e Tecnologia to obtain the Master’s degree in Environmental Engineering, profile in Ecological EngineeringSediment–bound contamination is a major concern factor in estuaries and other confined coastal water bodies, frequently subjected to anthropogenic sources of pollution. In order to investigate the effects and responses of the common cockle (Cerastoderma edule, L. 1558, Bivalvia: Cardiidae) to sediment contaminants and to assess the species’ potential as an indicator organism, the bivalve was subjected to a laboratorial translocation assay with sediments collected from distinct sites of the Sado Estuary (Portugal). Cockles were collected from a mariculture site of the Sado estuary (Portugal), herewith identified as site A, and exposed through 28–day, semi–static laboratorial essays, to sediments collected from three other sites (B, C and D) of the estuary that revealed different levels of metals, organic contaminants and physico–chemical properties and that ranged from globally unimpacted to moderately impacted levels when compared to available sediment quality guidelines. The animals were surveyed for bioaccumulation of metals (Ni, Cu, Zn, As, Cd and Pb) and organic contaminants (PAHs, PCBs and DDTs). Two sets of potential biomarkers were employed to assess toxicity: whole–body metallothionein (MT) induction and digestive gland histopathology. The bioaccumulation factor (BAF) and the biota-to-soil accumulation factor(BSAF) were estimated as ecological indices of exposure to metals and organic compounds. Significant positive correlations between BSAF and MT were found for PHAs, and between each factor (BSAF and BAF) and MT were found for Cd. Histopathological alterations were found in cockles exposed to all sediments where they were translocated. The digestive gland integrity was found to be especially compromised in cockles from sediment B and C and at day 28 from sediment A. Results allowed concluding that C. edule responds to sediment–bound contamination and is capable to regulate and eliminate both types of contaminants and might, therefore, be suitable for biomonitoring. Still, the sediment contamination levels do not explain the variation in bioaccumulation and MT levels, which may result from the moderate contaminant concentrations found in sediments and, more importantly, from yet unexplained xenobiotic interaction effects

Informática comunitaria y acciones de mejoramiento para la proyección social

18 p.La informática comunitaria, en su forma más simplificada, se puede entender como el uso de las tecnologías de información y comunicación con fines sociales. Una de las definiciones que mejor recoge este sentido de aprovechamiento define que: la tecnología de información y la comunicación proporciona recursos y herramientas que las comunidades y los individuos que viven en ellas pueden usar para conseguir sus metas en áreas como el desarrollo económico local, el desarrollo cultural, el activismo cívico, la salud física y mental de la comunidad, el medio ambiente, entre otras (Gurstein).Ponencia presentada para el V Coloquio Interno de Profesores sobre Responsabilidad Social 2005.Informática comunitaria en la Universidad Católica de Colombia Etapa descripción La perspectiva docente La perspectiva del estudiante La perspectiva de la comunidad Retos en desarrollo de informática comunitaria Estudio comparativo de proyección social de la Facultad de Ingeniería de Sistemas con respecto a otras universidades de Bogotá Portal de servicios para la difusión e integración de la proyección social y la comunidad en la Universidad Católica de Colombia Acciones de mejoramiento propuestas a partir de los proyectos ejecutados Bibliografí

Lattices of Generalized Skyrmions

Generalized Skyrme systems are those which include both the Skyrme and the Skyrme-Faddeev models through an interpolating parameter \alpha \in [0,1] the former corresponds to \alpha=0 and the latter to \alpha=1. Our numerical and analytical investigations centre around the \alpha=0 Skyrme crystal, its deformations, and its behaviour and symmetries as a function of \alpha, called the generalized Skyrme crystal. We show that a double square lattice emerges when the Skyrme crystal is deformed in a certain limit; we compare its energy with the one corresponding to a double hexagonal lattice and show that it has a lower energy-per-charge than its hexagonal counterpart. On the other hand, vortex-like structures with two 1-vortices (vortices of order 1) and two 1-antivortices, denoted V+AV+V+AV, appear when the Skyrme crystal is deformed in a different limit, as well as when the generalized Skyrme crystal is taken close to the Skyrme-Faddeev limit. This leads us to the study of generalized V+AV and V+AV+V+AV configurations, as a function of \alpha. We show that when these configurations are stacked in the axial direction, they exhibit some winding and linking properties as they are taken close to the Skyrme-Faddeev limit, where the V+AV+V+AV configurations appear to be more stable than their V+AV counterparts. Finally, the study of such configurations led to the discovery of two crystalline solutions whose properties are investigated in some detail: a 2-vortex/2-antivortex pair, denoted 2V+2AV, and a “multi-sheet” solution, both of which have a lower energy-per-charge than the V+AV+V+AV solution, in the Skyrme-Faddeev limit