Conceptual and socio-cognitive support for collaborative learning in videoconferencing environments

Studies have shown that videoconferences are an effective medium for facilitating communication between parties who are separated by distance. Furthermore, studies reveal that videoconferences are effective when used for distance learning, particularly when learners are engaged in complex collaborative learning tasks. However, as in face-to-face communication, learners benefit most when they receive additional support for such learning tasks. This article provides an overview of three empirical studies to illustrate more general insights regarding some of the more and less effective ways of supporting collaborative learning with videoconferencing. The focus is on conceptual support, such as structural visualization and socio-cognitive support, such as scripts. Based on the results of the three studies, conclusions can be drawn about the conceptual and socio-cognitive support measures that promote learning. Conclusions can also be reached about the need for employing both conceptual and socio-cognitive support to provide learners with the most benefit

Herschel-PACS imaging of protostars in the HH 1–2 outflow complex

We present 70 and 160 μm Herschel science demonstration images of a field in the Orion A molecular cloud that contains the prototypical Herbig-Haro objects HH 1 and 2, obtained with the Photodetector Array Camera and Spectrometer (PACS). These observations demonstrate Herschel’s unprecedented ability to study the rich population of protostars in the Orion molecular clouds at the wavelengths where they emit most of their luminosity. The four protostars previously identified by Spitzer 3.6–40 μm imaging and spectroscopy are detected in the 70 μm band, and three are clearly detected at 160 μm. We measure photometry of the protostars in the PACS bands and assemble their spectral energy distributions (SEDs) from 1 to 870 μm with these data, Spitzer spectra and photometry, 2MASS data, and APEX sub-mm data. The SEDs are fit to models generated with radiative transfer codes. From these fits we can constrain the fundamental properties of the protostars. We find luminosities in the range 12–84 L_⊙ and envelope densities spanning over two orders of magnitude. This implies that the four protostars have a wide range of envelope infall rates and evolutionary states: two have dense, infalling envelopes, while the other two have only residual envelopes. We also show the highly irregular and filamentary structure of the cold dust and gas surrounding the protostars as traced at 160 μm

The thermal power of aluminum nitride at temperatures between 1350 and 1650 deg C in argon and nitrogen atmospheres

The test apparatus for measuring the thermal voltage of aluminum nitride for temperature differences of up to + or - 60 C between 1350 and 1650 C is described. The thermal power and its homogeneous proportion are determined and the heat transfer of the migration ions resulting from the homogeneous thermal power is calculated. The conduction mechanism in aluminum nitride is discussed

QCD Propagators at non-vanishing temperatures

We investigate the behaviour of the gluon and ghost propagators, especially their infrared properties, at non-vanishing temperatures. To this end we solve their Dyson-Schwinger equations on a torus and find an infrared enhanced ghost propagator and an infrared vanishing gluon propagator.Comment: 2 pages, 2 figures; talk given by B.G. at the Erice summer school on Nuclear Physics, Sept. 16 -- 24, 2003, Erice, Ital

Towards a Taxonomy of Firms Engaged in International R&D Cooperation Programs: The Case of Spain in Eureka

El proceso innovador enfrenta una serie de fallos de mercado y por esta razón – y por ser considerado uno de los principales agentes del crecimiento económico en el mundo – un significativo número de políticas gubernamentales y supra-nacionales son diseñadas para promover el progreso tecnológico. En Europa la situación no podría ser diferente y la “Paradoja Europea” es utilizada como principal argumento para la implementación de iniciativas relacionadas a la innovación. Junto con estas políticas hay una creciente preocupación con su continua evaluación, teniendo como objetivo proveer feedbacks para la adaptación y adecuación de estos programas con las necesidades de los agentes involucrados. En este sentido, el presente paper desarrolla una evaluación de los impactos del Programa Eureka para el caso de las empresas españolas participantes en esta iniciativa y con proyectos concluidos entre los años 2000-2005 (a través de análisis de los informes finales de los proyectos). Un total de 77 empresas fueron abordadas con métodos cuantitativos (correlaciones, testes chi-cuadrado, análisis discriminante y análisis de cluster). Los resultados demuestran que la participación española en Eureka suele tener altos niveles de logros tecnológicos. Los logros comerciales parecen estar definidos por la calidad del funcionamiento del proyecto y por la capacidad de las empresas en explotar sus resultados en el mercado ya antes del fin del proyecto. Una tipología introductoria de los participantes es propuesta en 3 conglomerados: (1) Risky Innovators; (2) Inventors; y (3) Consistent Innovators.Innovation is a process that faces several “market failure” situations and for this reason – and for being considered one of the main drivers of economic growth throughout the world – a large number of governmental and supranational policies are designed to foster technological progress. In Europe this situation could not be any different and the “European Paradox” is used as the main argument for the implementation of innovation related initiatives. Along with these policies, there is an increasing concern with their continuous evaluation aiming at providing valuable feedback for these program’s adaptation and adequacy to the player’s needs. In this sense, this paper develops an evaluation of Eureka Programme’s impact for the case of Spanish companies participating in this initiative and that had projects finished in the period 2000-2005 (analysis performed through the information contained in Eureka’s Final Reports). A total of 77 firms were assessed through quantitative methods, namely correlations, chi-square tests, discriminant models and cluster analysis. Findings show that Spain participates in Eureka mainly through SMEs, and that the overall rate of technological achievements is impressively good. Commercial achievements seem to be influenced mainly by the quality of the project’s functioning and the capacity of firm’s exploiting results in the industry by the end of the project. A basic typology of participants is offered in which three clusters are built: (1) Risky Innovators; (2) Inventors; and (3) Consistent Innovators.Innovation Policy; Eureka Programme; Spanish Innovation System; R&D Collaboration, Políticas de Innovación; Programa Eureka; Sistema de Innovación Español; Colaboración en I+D.

Perturbative expansion of the QCD Adler function improved by renormalization-group summation and analytic continuation in the Borel plane

We examine the large-order behaviour of a recently proposed renormalization-group-improved expansion of the Adler function in perturbative QCD, which sums in an analytically closed form the leading logarithms accessible from renormalization-group invariance. The expansion is first written as aneffective series in powers of the one-loop coupling, and its leading singularities in the Borel plane are shown to be identical to those of the standard "contour-improved" expansion. Applying the technique of conformal mappings for the analytic continuation in the Borel plane, we define a class of improved expansions, which implement both the renormalization-group invariance and the knowledge about the large-order behaviour of the series. Detailed numerical studies of specific models for the Adler function indicate that the new expansions have remarkable convergence properties up to high orders. Using these expansions for the determination of the strong coupling from the the hadronic width of the $\tau$ lepton we obtain, with a conservative estimate of the uncertainty due to the nonperturbative corrections, $\alpha_s(M_\tau^2)= 0.3189^{+ 0.0173}_{-0.0151}$, which translates to $\alpha_s(M_Z^2)= 0.1184^{+0.0021}_{-0.0018}$.Comment: 15 pages latex using revtex, 4 figures; v2 corresponds to PRD version; compared to v1, power-correction estimates have been enlarged resulting in somewhat larger errors for alpha_S, relevant discussion has been provided, a reference has been added, minor typographical errors have been remove

Expansions of τ\tau hadronic spectral function moments in a nonpower QCD perturbation theory with tamed large order behavior

The moments of the hadronic spectral functions are of interest for the extraction of the strong coupling $\alpha_s$ and other QCD parameters from the hadronic decays of the $\tau$ lepton. Motivated by the recent analyses of a large class of moments in the standard fixed-order and contour-improved perturbation theories, we consider the perturbative behavior of these moments in the framework of a QCD nonpower perturbation theory, defined by the technique of series acceleration by conformal mappings, which simultaneously implements renormalization-group summation and has a tame large-order behavior. Two recently proposed models of the Adler function are employed to generate the higher order coefficients of the perturbation series and to predict the exact values of the moments, required for testing the properties of the perturbative expansions. We show that the contour-improved nonpower perturbation theories and the renormalization-group-summed nonpower perturbation theories have very good convergence properties for a large class of moments of the so-called "reference model", including moments that are poorly described by the standard expansions. The results provide additional support for the plausibility of the description of the Adler function in terms of a small number of dominant renormalons.Comment: 15 pages, latex using revtex, 4 figures; compared to v1, slightly improved figures and discussion, version to appear in PR

An Intergenerational Common Pool Resource Experiment

intergenerational common pool resources;growth and altruism;free-riding intentions