145 research outputs found

    The beauty of the mammalian vascular system

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    Beauty is a characteristic of objects that provides a perceptual experience of pleasure. In nature, aesthetic appreciation thereof has given rise to the mathematical search for good series (e.g. the Fibonacci series) and proportions (e.g. the Golden proportion) as important elements of beauty. In 1928 the mathematician George David Birkhoff introduced a formula for aesthetic measurement of an object. Birkhoff equation defines the aesthetic value as the amount of order divided by the complexity of the product. These two features can be measured easily in poetry, music, painting, architecture, etc. In the fine arts, it is the artist who manipulates both these features, but how does nature manage order and complexity in living organisms or their parts? Here we show how Birkhoff equation, applied to the mammalian vascular system of eight representative animals, results in new insights into the organization of the animal vascular system. We found that order and complexity are highly correlated in the mammalian vascular system (_R^2^_=0.9511). Accordingly, in nature both features are not independently managed in the manner of artists. We found significant differences among the Birkhoff aesthetic values in the mammalian arterial system, whereas no such differences exist in the venous system. We anticipate our approach to be useful in the study of morphogenesis and evolution of tree-like structures, employing the Birkhoff aesthetic value as a simple tool for conducting such studies

    Contribuciones al desarrollo de un sistema comercial de audio y videocomunicaci贸n basado en transmisi贸n por soporte f铆sico bifilar para aplicaciones inm贸ticas de bajo coste.

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    En esta tesis se muestra el desarrollo de diversas propuestas de bajo coste para la transmisi贸n de se帽ales anal贸gicas y digitales para aplicaciones industriales sobre un medio de transmisi贸n bifilar, el cual permite en su instalaci贸n topolog铆as en anillo, 谩rbol y bus. En algunos casos, la alimentaci贸n de los dispositivos que se conectan al medio de transmisi贸n se puede extraer del propio medio. En el caso de la transmisi贸n de datos digitales se ha considerado una transmisi贸n con una tasa de bits que permita su uso en la mayor铆a de las aplicaciones de la industria, tales como las comunicaciones inm贸ticas y dom贸ticas o la automoci贸n, as铆 como en algunas aplicaciones cient铆ficas. En todo caso son de prop贸sito general para aplicaciones de comunicaci贸n digital y alimentaci贸n por soporte bifilar, en las cuales la tasa binaria sea del orden de 1Mbps. Las propuestas que se realizan son consecuencia de la evoluci贸n tecnol贸gica en la implementaci贸n de sistemas comerciales para aplicaciones inm贸ticas, raz贸n por la cual, las prestaciones de cada una de las propuestas siguen un orden creciente. En primer lugar, se propone un m茅todo para transmitir informaci贸n en banda base de forma anal贸gica. Para ello se realiza una transmisi贸n diferencial y, con el uso de dispositivos aisladores y enrutadores, se consigue realizar comunicaciones punto a punto en instalaciones del tipo anillo, 谩rbol y bus. En segundo lugar, se muestra la transmisi贸n de la informaci贸n en forma modulada en frecuencia, utilizando la t茅cnica de multiplexaje por divisi贸n de frecuencia FDM; de esta forma se consiguen comunicaciones full-d煤plex y varios tipos de informaci贸n al mismo tiempo, como es el caso de transmitir audio y v铆deo simult谩neamente sobre el mismo par bifilar. Al igual que en el caso anterior, con la utilizaci贸n de aisladores y distribuidores se consiguen realizar comunicaciones punto a punto en instalaciones del tipo anillo, 谩rbol y bus. Cabe se帽alar que en este sistema se transmite la alimentaci贸n sobre el mismo par bifilar que lleva la informaci贸n modulada. Finalmente, se propone un tercer sistema que codifica la informaci贸n en forma digital, mediante un pulso senoidal, de manera que el valor digital est谩 codificado en el tiempo que trascurre entre un ciclo y el siguiente. La frecuencia utilizada para generar el ciclo es aproximadamente de 500 kHz con el fin de no superar el ancho de banda de los cables bifilares y, debido a que su longitud de onda es mayor que la longitud de la l铆nea de transmisi贸n en la mayor铆a de los casos, se puedan realizar instalaciones en anillo, 谩rbol y bus sin la necesidad de dispositivos intermedios tales como distribuidores o enrutadores, al no haber reflexiones.This thesis is showing the development of different low-cost proposals for transmitting analog and digital signals, focused on industrial applications through 2-wire media, allowing the use case of ring, tree and bus topologies. In some cases, the device supply is multiplexed into the transmission line, extracting this supply from this transmission media. In case use of digital data transmission, a baud rate has been considered, according to most of the industrial applications needs. As domotic, hotel or automotive markets, or as for some scientific applications, as well. Anyway, general purpose applications using digital transmission and power supply though 2-wire, where the bandwidth is around 1Mbps. The performed proposals are consequence of the technology evolution related to the commercial deployment of systems for hotel market applications, that is why the rising performance of each of the proposals. As a first point, the proposal is based on transmitting the information using an analog baseband method. So that the transmission is implemented in differential mode and, the point-to-point communication is achieved using inserting isolation devices and routers, into ring, tree and bus systems. As a second point, the information shows a frequency modulation using the FDM technique (Frequency Division Multiplexing), so this way, the system is able to establish multi-channel full-duplex communications, allowing asymmetric and heterogeneous simultaneous channels, as audio and video, over the 2-wire media. The point-to-point communication is achieved using inserting isolation devices and routers, into ring, tree and bus systems, as well. Finally, the third proposal is based on a system coding the information in a digital way, through a senoidal pulse, linking the coded digital value to the time period in between one cycle and the next one. The frequency for generating is around 500 Khz in order not to exceed the bandwidth of the 2-wire media, and considering the its wave length is longer than the transmission line in most of the use cases. This proposal allows ring, bus and tree systems, without the need of including net infrastructure devices as routers or switches, because no reflexed wave is produced

    Los centros educativos andaluces en internet

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    Normalmente se trata Internet desde el lado de sus posibilidades de aprendizaje. Con esta comunicaci贸n, queremos poner de manifiesto que, gracias al proyecto Averroes, muchos centros andaluces han podido contribuir a la gran telara帽a mundial, poniendo a disposici贸n de miles de personas informaci贸n sobre sus planes de estudio y ofertas de actividades, as铆 como intercambiar informaci贸n con otros centros, etc. Como consecuencia de este proyecto, encontramos hoy m谩s de 1500 centros Andaluces conectados en la red, cuyos alumnos y profesores han pasado de utilizar la red internet exclusivamente como medio de adquisici贸n de informaci贸n, a participar directamente en ella para compartir sus centros con todos aquellos que lo requieran

    Optimal approximation to unitary quantum operators with linear optics

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    Producci贸n Cient铆ficaLinear optical systems acting on photon number states produce many interesting evolutions, but cannot give all the allowed quantum operations on the input state. Using Toponogov鈥檚 theorem from differential geometry, we propose an iterative method that, for any arbitrary quantum operator U acting on n photons in m modes, returns an operator 浓 which can be implemented with linear optics. The approximation method is locally optimal and converges. The resulting operator 浓 can be translated into an experimental optical setup using previous results.Ministerio de Ciencia e Innovaci贸n- FEDER (grants PID2020-119418GB-I00 and PID2020-115930GA-I00)Junta de Castilla y Le贸n (project VA296P18)Universitat Jaume I (project UJI-B2018- 35 and grant UJI-B2018-10)Ministerio de Asuntos Econ贸micos y Transformaci贸n Digital (grant MTM2017-84851-C2-2)Ministerios de Ciencia e Innovaci贸n y de Universidades (grant PGC2018-096446-B-C22

    Mineralog铆a del Prospecto Bajo Agua Tapada, Catamarca, Argentina

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    El objeto de este trabajo es la definici贸n por vez primera de las asociaciones minerales (menas productivas y parag茅nesis de alteraci贸n hidrotermal)del llamado Prospecto Bajo Agua Tapada, de cara a la realizaci贸n de una primera valoraci贸n de su inter茅s; este trabajo se ha realizado tanto mediante mapeo y muestreo superficial como tras el estudio (mineral贸gico y geoqu铆mica)de unos 2800 m de sondeos realizados a testigo cont铆nuo

    Roflumilast N-oxide inhibits bronchial epithelial to mesenchymal transition induced by cigarette smoke in smokers with COPD

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    BACKGROUND: Epithelial to mesenchymal transition (EMT) is under discussion as a potential mechanism of small airway remodelling in COPD. In bronchial epithelium of COPD and smokers markers of EMT were described. In vitro, EMT may be reproduced by exposing well-differentiated human bronchial epithelial cells (WD-HBEC) to cigarette smoke extract (CSE). EMT may be mitigated by an increase in cellular cAMP. OBJECTIVE: This study explored the effects of roflumilast N-oxide, a PDE4 inhibitor on CSE-induced EMT in WD-HBEC and in primary bronchial epithelial cells from smokers and COPD in vitro. METHODS: WD-HBEC from normal donors were stimulated with CSE (2.5%) for 72 h in presence of roflumilast N-oxide (2 nM or 1 渭M) or vehicle. mRNA and protein of EMT markers 伪SMA, vimentin, collagen-1, E-cadherin, ZO-1, KRT5 as well as NOX4 were quantified by real-time quantitative PCR or protein array, respectively. Phosphorylated and total ERK1/2 and Smad3 were assessed by protein array. cAMP and TGF尾1 were measured by ELISA. Reactive oxygen species (ROS) were determined by DCF fluorescence, after 30 min CSE (2.5%). Apoptosis was measured with Annexin V/PI labelling. In some experiments, EMT markers were determined in monolayers of bronchial epithelial cells from smokers, COPD versus controls. RESULTS: Roflumilast N-oxide protected from CSE-induced EMT in WD-HBEC. The PDE4 inhibitor reversed both the increase in mesenchymal and the loss in epithelial EMT markers. Roflumilast N-oxide restored the loss in cellular cAMP following CSE, reduced ROS, NOX4 expression, the increase in TGF尾1 release, phospho ERK1/2 and Smad3. The PDE4 inhibitor partly protected from the increment in apoptosis with CSE. Finally the PDE4 inhibitor decreased mesenchymal yet increased epithelial phenotype markers in HBEC of COPD and smokers. CONCLUSIONS: Roflumilast N-oxide may mitigate epithelial-mesenchymal transition in bronchial epithelial cells in vitro

    Information and Communication Technologies and initial teacher training. Digital models and competences

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    Hablar de la formaci贸n del profesorado en Tecnolog铆as de la Informaci贸n y la Comunicaci贸n (TIC), implica el estudio de diferentes dimensiones y principios, contemplando las indicaciones que han apuntado distintos estudios y trabajos. En la sociedad actual, es claro que la significaci贸n de las TIC para mejorar la calidad y el rendimiento educativo, no viene exclusivamente determinado por su presencia, sino tambi茅n por diferentes transformaciones que implican pasar de utilizarlas 煤nicamente como una forma de consumir conocimientos, a verlas como herramientas para enriquecerlos, crearlos y generarlos. Desde esta perspectiva, la inversi贸n en desarrollo profesional es m谩s importante que la inversi贸n en recursos asociados a la tecnolog铆a, siendo un aspecto importante para su incorporaci贸n, el no plantearse 煤nicamente su utilizaci贸n para hacer mejor las cosas que hacemos sin ellas, sino para hacer cosas completamente distintas. Desde esta 贸ptica, planteamos el presente art铆culo en el que se describe un recorrido por algunas de las bases y modelos, analizando la problem谩tica de la formaci贸n en las competencias digitales que debe poseer el profesorado a la hora de incorporarlas en su pr谩ctica docente y profesional.The talk about teacher training in Information and Communication Technologies implies the study of different dimensions and principles, contemplating the indications that different studies and papers have pointed out. In today's society, it is clear that the significance of ICTs to improve quality and educational performance is not only determined by their presence, but also by different transformations that involve going from using them only as a way to consume knowledge, to see them as tools to enrich them, create them and generate them. From this point, investment in professional development is more important than investing in resources related to technology, being an important factor for its inclusion, not only considering its use to do better the things we do without them, but to do things completely different. From this point of view, we present this article, which describes a journey through some of the bases and models, analysing the problem of training in the digital competences that must be possessed by teachers when incorporating them into their teaching and professional practice

    Higher accuracy approximate solution for oscillations of a mass attached to a stretched elastic wire by rational harmonic balance method

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    A second-order modified rational harmonic balance method is used for approximately solve the nonlinear differential equation that governs the oscillations of a system typified as a mass attached to a stretched elastic wire for which the restoring force for this oscillator has an irrational term with a parameter lambda that characterizes the system. A frequency-amplitude relation is constructed and this frequency is valid for the complete range of oscillation amplitudes A and parameter lambda, and excellent agreement of the approximate frequencies with the exact one is demonstrated and discussed. The discrepancy between the approximate frequency and the exact one never exceed 0.12%. This error corresponds to lambda = 1. while for lambda < 1 the relative error is much lower. For example, its value is lower than 0.017% for lambda = 0.5
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