Search results for "source"
showing 10 items of 6139 documents
Wideband THz time domain spectroscopy based on optical rectification and electro-optic sampling
2013
We present an analytical model describing the full electromagnetic propagation in a THz time-domain spectroscopy (THz-TDS) system, from the THz pulses via Optical Rectification to the detection via Electro Optic-Sampling. While several investigations deal singularly with the many elements that constitute a THz-TDS, in our work we pay particular attention to the modelling of the time-frequency behaviour of all the stages which compose the experimental set-up. Therefore, our model considers the following main aspects: (i) pump beam focusing into the generation crystal; (ii) phase-matching inside both the generation and detection crystals; (iii) chromatic dispersion and absorption inside the c…
Geometrical Transformations In The Fraunhofer Plane
1987
A virtual display of the Fraunhofer diffraction pattern is generated solely by illuminating the object with a point source. If this pattern is imaged with an anamorphic system, several linear geometrical transformations can be achieved. Furthermore, a nonsymmetrical Fourier transformer with a variable degree of anamorphic magnification on the Fraunhofer pattern can be implemented.
Delphi study for the design and validation of a questionnaire about digital competences in higher education
2016
The study of digital competence remains an issue of interest for both the scientific community and the supranational political agenda. This study uses the Delphi method to validate the design of a questionnaire to determine the perceived importance of digital competence in higher education. The questionnaire was constructed from different framework documents in digital competence standards (NETS, ACLR, UNESCO). The triangulation of non-parametric techniques made it possible to consolidate the results obtained through the Delphi panel, the suitability of which was highlighted through the expert competence index (K). The resulting questionnaire emerges as a good tool for undertaking future na…
Estratègies de formació i informació per implantar l'OpenCourseWare a la Universitat de València. Participació dels usuaris potencials en el procés
2013
Objectius: conèixer les necessitats de formació que diuen tenir els docents de les titulacions en ciències de la salut de la Universitat de València per ser competents en la incorporació de l'OpenCourseWare. Conèixer quines estratègies de màrqueting i informació pensen aquests docents que s'haurien de dissenyar per augmentar el dipòsit de materials. -- Metodologia: estudi qualitatiu amb entrevistes semiestructurades al professorat de la Universitat de València. -- Resultats: les necessitats de formació dels docents per implantar l'OpenCourseWare a la Universitat de València varien depenent de les seves característiques relacionades amb l'experiència docent, el domini de les TIC i la disposi…
Estrategias de formación e información para implantar el OpenCourseWare en la Universidad de Valencia. Participación de los usuarios potenciales en e…
2013
Objetivos: conocer las necesidades de formación que dicen tener los docentes de las titulaciones en ciencias de la salud de la Universidad de Valencia para ser competentes en la incorporación del OpenCourseWare. Conocer qué estrategias de marketing e información piensan estos docentes que se deberían diseñar para aumentar el depósito de materiales. -- Metodología: estudio cualitativo con entrevistas semiestructuradas al profesorado de la Universidad de Valencia. -- Resultados: las necesidades de formación de los docentes para implantar el OpenCourseWare de la Universidad de Valencia varían dependiendo de sus características relacionadas con la experiencia docente, el dominio de las TIC y la…
Uso de materiales didácticos digitales en las aulas de Primaria
2019
El presente artículo se analizan las prácticas docentes en aulas de Educación Primaria en las que se emplean plataformas digitales comerciales o institucionales, así como otros materiales didácticos digitales. Se pretende dar respuesta, principalmente, a las siguientes preguntas: ¿Qué materiales didácticos digitales se utilizan en las aulas de Primaria? ¿Qué tipología de actividades se llevan a cabo con estos recursos? ¿Cómo se organiza el aula y qué metodologías didácticas se emplean? Para el desarrollo de este estudio, se toman como instrumentos de recogida de datos las entrevistas a docentes y las observaciones, de aula y de espacios, efectuadas en tres aulas de Canarias, Valencia y Gali…
A SOLUTION TO THE DILEMMA BETWEEN R&D EXPANSION AND THE PRODUCTIVITY DECLINE: LESSONS FROM THE R&D MODELS IN AMAZON AND FINLAND
2019
As a consequence of the two-faced nature of information and communication technology (ICT), a majority of ICT leaders have been confronting the critical problem of a dilemma between R&D expansion and productivity decline in the digital economy. However, Amazon has been able to accomplish a skyrocketing increase in R&D and market capitalization. Finland has also accomplished balanced advancement not only of welfare but also economic resurgence. This paper attempted to elucidate the miracle of two ICT leaders. By means of a comparative empirical analysis of respective development trajectories, the sources of their success were analyzed thereby the comparative advantage and disadvantag…
Chemosensory assessment of rival competitive ability and scent-mark function in a lizard, Podarcis hispanica
2007
Recent studies have stressed the role of scent marks as signals potentially mediating competitor assessment. According to this view, receivers may use scent marks to derive information about the costs of exploiting a given area, but few studies have directly addressed this hypothesis. One of its main predictions is that scent marks should reflect a signaller's competitive ability. We simulated the situation faced by an intruding male when entering the scent-marked territories of rival males of varying competitive ability to test predictions about the role of scent marks in a lizard, Podarcis hispanica. We report that males were attracted to areas marked by males of similar or higher competi…
Balls into non-uniform bins
2014
Balls-into-bins games for uniform bins are widely used to model randomized load balancing strategies. Recently, balls-into-bins games have been analysed under the assumption that the selection probabilities for bins are not uniformly distributed. These new models are motivated by properties of many peer-to-peer (P2P) networks, which are not able to perfectly balance the load over the bins. While previous evaluations try to find strategies for uniform bins under non-uniform bin selection probabilities, this paper investigates heterogeneous bins, where the "capacities" of the bins might differ significantly. We show that heterogeneous environments can even help to distribute the load more eve…
Context Trees, Variable Length Markov Chains and Dynamical Sources
2012
Infinite random sequences of letters can be viewed as stochastic chains or as strings produced by a source, in the sense of information theory. The relationship between Variable Length Markov Chains (VLMC) and probabilistic dynamical sources is studied. We establish a probabilistic frame for context trees and VLMC and we prove that any VLMC is a dynamical source for which we explicitly build the mapping. On two examples, the "comb" and the "bamboo blossom", we find a necessary and sufficient condition for the existence and the uniqueness of a stationary probability measure for the VLMC. These two examples are detailed in order to provide the associated Dirichlet series as well as the genera…