218 research outputs found

    Evaluation of alfalfa varieties in the province of Salamanca

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    XLV Reunión Científica de la SEEP (Sesión: Producción Vegetal)Se realiza un estudio comparativo de 26 variedades registradas de alfalfa (Medicago sativa L.), cultivadas en regadío en la provincia de Salamanca, evaluando la producción y contenido de proteína bruta. El primer año del experimento se realizaron cuatro cortes, siendo la producción en el primer corte significativamente más baja que en el resto. La producción total anual oscila entre 8160 kg ha-1 en la variedad “Baraka” y 10109 kg ha-1 en “Bar MS 82439”, con un valor medio sobre todas las variedades de 9370 kg ha-1. El contenido de proteína bruta oscila entre 19,30% en la variedad “Almar” y 23,47% en la variedad “Aragón”.{ENG}Dry matter production and protein content were evaluated in 26 alfalfa (Medicago sativa L.) varieties grown under irrigation in the province of Salamanca. In the first year four harvests were made. The dry matter production of the first haverst was the lowest. The annual dry matter production ranged between 8160 kg ha-1 in “Baraka” and 10109 kg ha-1 in “Bar MS 82439”, with a mean value across varieties of 9370 kg ha-1. The protein content ranged between 19.30% in “Almar” and 23.47% in “Aragón” variety.Este trabajo ha sido realizado con financiación del Ministerio de Ciencia y Tecnología (AGL2002-02766 AGR-FOR

    El Prácticum como enseñanza reflexiva: una propuesta de innovación didáctica realizada en la Escuela de Magisterio de la UAH

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    En este artículo presentamos una experiencia piloto de innovación referida al Prácticum, realizada en la E. de Magisterio de la UAH., durante los cursos 2006-07 y 2007-08. La experiencia, que parte de la premisa de formar un profesor crítico y con criterio, nos ha llevado a situarnos en el modelo del profesor refl exivo. Empezamos indicando el origen de la propuesta, y más tarde justifi camos las bases del modelo, explicamos la metodología que hemos empleado e indicamos las conclusiones que se derivan de la experiencia.                                                                                                                                  This article presents a pilot and innovative experience dealing with the Teaching Practice that has been carried out at the Teacher Training School of the University of Alcalá during the academic years 2006/07 and 2007/08. This experience is based on the premise of educating a teacher so that s/he can become a person of sound judgement and constructive criticism and it has made us choose the refl exive teacher model. Our study begins by indicating the background of our proposal and continues by reasoning the basis of that model. Then we explain the methodology we have used and we fi nally point out the conclusions we have reached from this innovative experience

    High Speed Finish Turning of Inconel 718 Using PCBN Tools under Dry Conditions

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    Inconel 718 is a superalloy, considered one of the least machinable materials. Tools must withstand a high level of temperatures and pressures in a very localized area, the abrasiveness of the hard carbides contained in the Inconel 718 microstructure and the adhesion tendency during its machining. Mechanical properties along with the low thermal conductivity become an important issue for the tool wear. The finishing operations for Inconel 718 are usually performed after solution heat treatment and age hardening of the material to give the superalloy a higher level of hardness. Carbide tools, cutting fluid (at normal or high pressures) and low cutting speed are the main recommendations for finish turning of Inconel 718. However, dry machining is preferable to the use of cutting fluids, because of its lower environmental impact and cost. Previous research has concluded that the elimination of cutting fluid in these processes is feasible when using hard carbide tools. Recent development of new PCBN (Polycrystalline Cubic Boron Nitride) grades for cutting tools with higher tenacity has allowed the application of these tool grades in the finishing operations of Inconel 718. This work studies the performance of commercial PCBN tools from four different tool manufacturers as well as an additional grade with equivalent performance during finish turning of Inconel 718 under dry conditions. Wear tests were carried out with different cutting conditions, determining the evolution of machining forces, surface roughness and tool wear. It is concluded that it is not industrially viable the high-speed finishing of Inconel 718 in a dry environment.This work was supported by the Spanish Ministry of Economy and Competitiveness and FEDER program under grant DPI2014-56137-C2-2-R

    Eigenvector centrality of nodes in multiplex networks

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    We extend the concept of eigenvector centrality to multiplex networks, and introduce several alternative parameters that quantify the importance of nodes in a multi-layered networked system, including the definition of vectorial-type centralities. In addition, we rigorously show that, under reasonable conditions, such centrality measures exist and are unique. Computer experiments and simulations demonstrate that the proposed measures provide substantially different results when applied to the same multiplex structure, and highlight the non-trivial relationships between the different measures of centrality introduced

    Combined TGA-MS kinetic analysis of multistep processes. Thermal decomposition and ceramification of polysilazane and polysiloxane preceramic polymers.

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    The polymer-to-ceramic transformation kinetics of two widely employed ceramic precursors; 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane (TTCS) and polyureamethylvinylsilazane (CERASET) have been investigated using coupled thermogravimetry and mass spectrometry (TG-MS), Raman, XRD and FTIR. The thermally induced decomposition of the pre-ceramic polymer is the critical step in the synthesis of Polymer Derived Ceramics (PDCs) and an accurate kinetic modeling is key to attain a complete understanding of the underlying process and to attempt any behavior predictions. However, obtaining a precise kinetic description of processes of such complexity, consisting of several largely overlapping physico-chemical processes comprising the cleavage of the starting polymeric network and the release of organic moieties, is extremely difficult. Here, using the evolved gases detected by MS as a guide it has been possible to determine the number of steps that compose the overall process, which was subsequently resolved using a semiempirical deconvolution method based on the Frasier-Suzuki function. Such function is more appropriate that the more usual Gaussian or Lorentzian functions since it takes into account the intrinsic asymmetry of kinetic curves. Then, the kinetic parameters of each constituent step was independently determined using both model-free and model-fitting procedures, finding the processes obey mostly diffusion models that can be attributed to the diffusion of the released gases through the solid matrix. The validity of the obtained kinetic parameters was tested not only by the successful reconstruction of the original experimental curves but also by predicting the kinetic curves of the overall processes yielded by different thermal schedules and by a mixed TTCS-CERASET precursorEspaña Mineco FEDER CTQ2011-27626 CTQ2014-52763-C2-1-RJunta de Andalucia FEDERTEP-7858 TEP-190

    Cortistain is expressed in a distinct subset of cortical interneurons

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    Cortistatin is a presumptive neuropeptide that shares 11 of its 14 amino acids with somatostatin. In contrast to somatostatin, administration of cortistatin into the rat brain ventricles specifically enhances slow wave sleep, apparently by antagonizing the effects of acetylcholine on cortical excitability. Here we show that preprocortistatin mRNA is expressed in a subset of GABAergic cells in the cortex and hippocampus that partially overlap with those containing somatostatin. A significant percentage of cortistatin-positive neurons is also positive for parvalbumin. In contrast, no colocalization was found between cortistatin and calretinin, cholecystokinin, or vasoactive intestinal peptide. During development there is a transient increase in cortistatin-expressing cells in the second postnatal week in all cortical areas and in the dentate gyrus. A transient expression of preprocortistatin mRNA in the hilar region at P16 is paralleled by electrophysiological changes in dentate granule cells. Together, these observations suggest mechanisms by which cortistatin may regulate cortical activity

    A Model-Driven Engineering Approach for the Service Integration of IoT Systems

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    With the development of IoT devices and web services, the objects of the real world are more interconnected, which allows applications to extend their characteristics in different fields, including industrial or home environments, among other possible examples such as health, trade, transport, or agriculture. However, this development highlights the challenge of interoperability, because devices are heterogeneous and use different communication protocols and different data formats. For this reason, we propose a model for point-to-point integration in three-layer IoT applications: (a) hardware, which corresponds to the physical objects (controller, sensor and actuator), (b) communication, which is the bridge that allows the exchange of data between a MQTT queue and REST web services, and (c) integration, which establishes a sequence of transactions to coordinate the components of the system. For this purpose, a metamodel, a graphic editor and a code generator have been developed that allow the developer to design IoT systems formed by heterogeneous components without having in-depth knowledge of every hardware and software platform. In order to validate our proposal, a smart home scenario has been developed, with a series of sensors and actuators that combined show a complex behavior

    A Recommender System for Component-based Applications using Machine Learning Techniques

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    Software designers are striving to create software that adapts to their users’ requirements. To this end, the development of component-based interfaces that users can compound and customize according to their needs is increasing. However, the success of these applications is highly dependent on the users’ ability to locate the components useful for them, because there are often too many to choose from. We propose an approach to address the problem of suggesting the most suitable components for each user at each moment, by creating a recommender system using intelligent data analysis methods. Once we have gathered the interaction data and built a dataset, we address the problem of transforming an original dataset from a real component-based application to an optimized dataset to apply machine learning algorithms through the application of feature engineering techniques and feature selection methods. Moreover, many aspects, such as contextual information, the use of the application across several devices with many forms of interaction, or the passage of time (components are added or removed over time), are taken into consideration. Once the dataset is optimized, several machine learning algorithms are applied to create recommendation systems. A series of experiments that create recommendation models are conducted applying several machine learning algorithms to the optimized dataset (before and after applying feature selection methods) to determine which recommender model obtains a higher accuracy. Thus, through the deployment of the recommendation system that has better results, the likelihood of success of a component-based application is increased by allowing users to find the most suitable components for them, enhancing their user experience and the application engagement

    Photonic heterodyne pixel for imaging arrays at microwave and MM-Wave frequencies

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    The use of photonic heterodyne receivers based on semiconductor optical amplifiers to be used in imaging arrays at several GHz frequencies is evaluated. With this objective, a 3×3 imaging array based on such photonic pixels has been fabricated and characterized. Each of the receiving optoelectronic pixels is composed of an antipodal linear tapered slot antenna (LTSA) that sends the received RF signal directly to the electrical port of a semiconductor opticalamplifier (SOA) acting as the optoelectronic mixer. Both the local oscillator (LO) and the intermediate frequency (IF) signals are directly distributed to/from the array pixels using fiber optics, that allows for remote LO generation and IF processing to recover the image. The results shown in this work demonstrate that the performances of the optoelectronic imaging array are similar to a reference all-electronic array, revealing the possibility of using this photonic architecture in future high-density, scalable, compact imaging arrays in microwave and millimeter wave ranges.Publicad
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