2,440 research outputs found

    Reducción de los tiempos de observación en la evaluación del observación en la evaluación del comportamiento de conejas en producción. Análisis metodológico.

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    El objetivo de este trabajo fue evaluar diferentes técnicas de muestreo que redujeran el tiempo total de observación necesario para estimar el comportamiento de conejas alojadas en dos tipos de jaulas (convencionales vs. enriquecidas) y en dos estados fisiológicos distintos (gestantes vs. lactantes). Para ello, se compararon grabaciones completas de 24 h (método control de referencia) con estimaciones obtenidas a partir de grabaciones de diferente duración y frecuencia (métodos regular corto y regular largo y métodos irregulares de 6h y de 8h). A partir de los resultados obtenidos se observa que los métodos regulares se ajustaron mejor al método de referencia de 24h que los irregulares. Desde un punto de vista práctico el método regular corto sería el ideal, al reducir considerablemente el número total de horas de observación y análisi

    LPS Auto-Calibration Algorithm with Predetermination of Optimal Zones

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    Accurate coordinates for active beacons placed in the environment are required in Local Positioning Systems (LPS). These coordinates and the distances (or differences of distances) measured between the beacons and the mobile node to be localized are inputs to most trilateration algorithms. As a first approximation, such coordinates are obtained by means of manual measurements (a time-consuming and non-flexible method), or by using a calibration algorithm (i.e., automatic determination of beacon coordinates from ad hoc measurements). This paper presents a method to calibrate the beacons’ positions in a LPS using a mobile receiver. The method has been developed for both, spherical and hyperbolic trilateration. The location of only three test points must be known a priori, while the position of the other test points can be unknown. Furthermore, the paper describes a procedure to estimate the optimal positions, or approximate areas in the coverage zone, where the test-points necessary to calibrate the ultrasonic LPS should be placed. Simulation and experimental results show the improvement achieved when these optimal test-points are used instead of randomly selected ones

    Medida de magnitudes con GeoGebra en la formación de maestros

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    En este trabajo presentamos una propuesta de trabajo diseñada con GeoGebra centrada en la medida de magnitudes continuas y dirigida a estudiantes de tercer ciclo de Educación Primaria. Esta propuesta se organiza en torno a tres módulos. El primero se centra en el manejo de algunas herramientas básicas de medida e incluye el uso de la cuadrícula de GeoGebra para realizar medidas de manera directa. El segundo módulo explora las condiciones que deben satisfacer tres segmentos para que pueda construirse con ellos un triángulo. El tercer módulo analiza la relación entre área y perímetro en un cuadrilátero. Tras realizar esta actividad con futuros maestros, en el contexto de la primera asignatura de matemáticas que cursan en el Grado en la Universidad de Granada, presentamos el análisis de las respuestas obtenidas

    Turbiditas carbonatadas del Cretácico inferior en el Arroyo Bercho, Prebético de Jaén: Interpretación genética e implicaciones paleogeográficas

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    [ES] El análisis de las características sedimentarias de las turbiditas carbonatadas permite precisar la interpretación paleogeográfica del Prebético de Jaén, durante el Cretácico. Se pueden distinguir dos asociaciones de facies: a) Turbiditas de estatificación fina, intercaladas en abundante sedimento pelágico, e interpretadas como facies de borde de lóbulo. b) Cuerpos turbidíticos lenticulares interpretados como lóbulos de depósito formados por agradación. Aparecen asociadas a una serie depositada en una cuenca que progresivamente se fue haciendo más somera y que terminó con la implantación de una plataforma carbonatada en el Cenomanense. Se calcula que el depósito de las turbidítas debió realizarse a unos pocos centenares de metros de profundidad.[EN] The analysis of the sedimentary characteristics of the carbonate turbidites allows to accurate the paleogeographic interpretation of the Prebetie of laen. Two types of facies associations can be distinguished: a) Thin bedded turbidites> as intercalations into mainly hemipelapic sediments, interpreted as lobe fringe facies, b) Lents like turbiditie bodies corresponding to agradational depositional lobes. They occur associated to an shallowing upward sequence ending with Cenomanian carbonated platform facies. The turbiditic deposit supodselly took place in a few hundreds meters deep sedimentary basin.Trabajo patrocinado por la C.A.I.C.Y.T., dentro del proyecto «El Mesozoico de las Cordilleras Béticas» realizado en este centro del C.S.I.C.Peer reviewe

    Validación de una escala para evaluar la adicción a Internet

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    La definición del uso prolongado de Internet como una adicción no es clara. Se han utilizado diversas estrategias en un intento de recuperar datos empíricos que permitan suponer este uso como una adicción. Destaca el diseño de instrumentos de evaluación para la adicción a Internet. Sin embargo, existen pocos instrumentos confiables y válidos que permitan su evaluación. El propósito del presente estudio fue desarrollar un instrumento que permita medir la adicción a Internet, el cual integra los parámetros de la adicción a sustancias junto con los parámetros de adicción conductual. Se utilizó una escala Likert con 29 ítems y se aplicó a 128 estudiantes universitarios que cum-plieron con los criterios establecidos. Los resultados indicaron la presencia de 6 factores que contienen un total de 26 ítems y que lograron explicar el 69.47% de la varianza total. Además, el instrumento en general obtuvo una con-sistencia interna aceptable con un alfa de Cronbach de 0.917. De las variables cuyos pesos factoriales cargaron de forma importante, se obtuvieron alfas que van desde 0.86 para el primer factor a 0.64 para el sexto factor. Se sugiere que el instrumento es una opción válida y confiable que permitirá evaluar el uso adictivo de InternetThe definition of prolonged Internet use as an addiction is unclear. Various strategies have been used to recover empirical data that allow us to consider this use as an addiction. The design of assessment instruments for Internet addiction stands out. However, there are few reliable and valid instruments that allow its evaluation. The purpose of this study was to develop an instrument to measure Internet addiction, which integrates the parameters of subs-tance addiction together with the parameters of behavioral addiction. A Likert scale with 29 items was used and it was applied to 128 university students who met the established criteria. The results indicated the presence of 6 factors that contain a total of 26 items and that managed to explain 69.47% of the total variance. In addition, the instrument in general obtained an acceptable internal consistency with a Cronbach’s alpha of 0.917. Of the variables whose factorial weights loaded significantly, alphas ranging from 0.86 for the first factor to 0.64 for the sixth factor were obtained. It is suggested that the instrument is a valid and reliable option that will allow evaluating addictive use of the Internet

    Efecto del tipo de jaula sobre el comportamiento de conejas

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    El objetivo de este ensayo fue evaluar el efecto del tipo de jaula (convencional vs. enriquecida) y el estado fisiológico de las conejas (gestación vs. lactación) sobre su comportamiento. Se realizaron grabaciones de 12 conejas multíparas durante 24 h en dos momentos distintos. Los comportamientos observados se clasificaron en tres grupos independientes (localización, locomoción y acciones). Se observó una predominancia clara por el uso del reposapatas (principalmente en la fase de lactación), pero este tiempo disminuyó significativamente en jaulas enriquecidas debido al uso de la plataforma (67,1 vs. 48,2%; Pmenor que0,05). Las conejas permanecieron tumbadas y sentadas el 78,4 y 20,7% del día, respectivamente, sin tener efecto ni el tipo de jaula ni el estado fisiológico. Las conejas se ponían de pie únicamente para comer u oler las heces retenidas sobre la plataforma. Las conejas se mostraron más nerviosas en la fase de lactación tratando de huir de los gazapos, siendo esta huida exitosa cuando las conejas tenían la posibilidad de utilizar la plataforma. Las conejas gestantes estuvieron significativamente más tiempo que las lactantes acicalándose, mordiendo barrotes e interaccionando con las vecinas (Pmenor que0,01; 0,05 y 0,05, respectivamente). Las conejas lactantes dedicaron más tiempo a beber (Pmenor que0,05) que las gestantes. De este trabajo se desprende que el aumento del espacio disponible con la colocación de una plataforma elevada podría ser una buena alternativa para la mejora del bienestar de las conejas, sobre todo en la fase final de la lactación, aunque la retención de heces sobre la plataforma y las deyecciones pueden ocasionar problemas de higiene

    Influence of the Synthesis Method on the Preparation Composites Derived from TiO2-LDH for Phenol Photodegradation

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    Three different TiO2 catalysts are prepared using different methods. MgAl-CO32− layered double hydroxides (LDH) were obtained by the sol-gel method. In the preparation of the composites, the three photocatalysts were combined with LDH following different methodologies. The composites were characterized using X-ray diffraction (XRD), specific surface area (SA), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The influence of the synthesis method on the preparation of the composites was evaluated by analyzing their photocatalytic activity against phenol as a model organic pollutant under UV irradiation. The photocatalytic activity of the composites improves when the chemical interaction, determined by XPS, between the TiO2 and the LDH decreases. The same happens when the ratio of the anatase-rutile phases, determined by XRD, approaches optimum (80:20%). The effect of the composite concentration in the solution (0.5–2.0 g/L) was investigated, and the light-shielding phenomenon due to high composite concentration decreases the phenol photodegradation. The reduction of photocatalytic activity in reuse cycles is due to loss and partial deactivation of the material. The elimination of phenol is attributed primarily to the photocatalytic process due to the generation of ●OH radicals and to a lesser extent the adsorption process also present in the samples

    Computational study of coronoid carbazole based Macrocycles: influence of isomerism.

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    Carbazole (Cz) units have been recognized as crucial conjugated cores in organic electronics due to their good electro- and photoactive properties, such as high hole-transporting mobilities, when compared to other heterocycles. On the other hand, conjugated macrocycles should be useful building blocks for the construction of 2D porous surface networks or 3D inclusion complexes among other supramolecular structures.2 One of the most interesting features of conjugated cyclic oligomers is that their electronic, structural, and optical properties can be tuned as a function of their interior and exterior domains. Therefore, a systematic study of conjugated macrocycles with well-defined diameters is of crucial importance to establish the structure-property relationships of these materials. For that purpose, we carried out a purely theoretical study of coronoid molecules based on three different indolocarbazoles (ICz) structural isomers (see Figure 1) as indolo[2,3-a]carbazole (23a-4MC), indolo[2,3-b]carbazole (23b-4MC) and indolo[3,2-b]carbazole (32b-4MC), which contain four indolecarbazole units (4MC). This work aims to identify new macrostructures with interesting electronic properties as well as to display the usefulness of the theoretical tools to advance knowledge in the organic electronics field. Overall, this investigation contributes to elucidating the electronic properties of coronoid macrocycles, guiding experimental chemists to produce new molecules with desirable properties.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Dietary level of fibre and age at weaning affect the proliferation of Clostridium perfrigens in the caecum, the incidence of Epizootic Rabbit Enteropathy and the performance of fattening rabbits

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    An experiment was conducted to investigate the effects of dietary fibre content and weaning age on Clostridium perfringens proliferation in the caecum and fattening mortality in growing rabbits farmed in a facility having Epizootic Rabbit Enteropathy. The experiment consisted in a 2 × 2 factorial arrangement with two weaning ages (28 days vs. 42 days) and two levels of dietary neutral detergent fibre assayed with a heat stable amylase and expressed exclusive of residual ash (aNDFom; 330 g/kg vs. 425 g/kg). Controls were made during two consecutive experimental periods that differed in hygienic environmental conditions by modifying the intensity of cleaning and disinfection in the farm previous to the trial. An interaction (P<0.001) was detected among the independent variables studied on Cl. perfringens enumeration in the caecal contents, as minimal values for this trait were obtained in non-medicated animals reared in a clean environment, and especially when they were weaned at a later age and fed the diet with the lower fibre content. The treatments studied also led to a variation in fattening mortality (from 4.7% to 34.0%), which was highly and positively correlated (P<0.001) to the average Cl. perfringens caecal counts in each combination of treatments. The results of the current study indicate that high counts of Cl. perfringens in the caecum can be used as an indicator of Epizootic Rabbit Enteropathy, and suggest that strategies designed to control its proliferation in the caecum might help to limit fattening mortality in rabbit fed diets not-medicated with antibiotics

    Syngas/H2 production from bioethanol in a continuous Chemical-Looping Reforming prototype

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    Chemical-looping reforming (CLR) allows H2 production without CO2 emissions into the atmosphere. The use of a renewable fuel, bioethanol, in an auto-thermal CLR process has the advantage to produce H2 with negative CO2 emissions. This work presents the experimental results obtained in a continuously operating CLR unit (1 kWth) using ethanol as fuel. Two NiO-based oxygen carriers were used during more than 50 h of operation. The influence of variables such as temperature, water-to-fuel and oxygen-to-fuel molar ratios was analysed. Full conversion of ethanol was accomplished and carbon formation was easily avoided. A syngas composed of ≈ 61 vol.% H2, ≈ 32 vol.% CO, ≈ 5 vol.% CO2 and ≈ 2 vol.% CH4 was reached at auto-thermal conditions for both materials. Gas composition was closed to the given by the thermodynamic equilibrium. These results demonstrate the technical viability of H2/syngas production by using bioethanol in an auto-thermal CLR process.This work is partially supported by the Spanish Ministry for Science and Innovation (MICINN project ENE2011-26354) and the European Regional Development Fund (ERDF), and by CTGAS-ER (project OTT20130989). A. Serrano also thanks the Spanish Ministry of Economy and Competitiveness for the F.P.I. fellowshipPeer reviewe
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