YouTube celebrity endorsement: audience evaluation of source attributes and response to sponsored content. A case study of influencer Verdeliss

This article analyses follower response to the growing number of product endorsements present in YouTube videos published under the username “Verdeliss” by Estefanía Unzu Ripoll, Spain’s most popular YouTube influencer on the topic of maternity and childcare. Results of a self-administered online survey of 949 Verdeliss followers focused on their individual evaluations of source attributes indicate that Unzu Ripoll’s YouTube fans tend to buy products she endorses on the basis of her perceived likeability and expertise, and that the overall influence she exerts on their purchasing decisions is slight. In closing, the authors offer insights into how social media influencers can enhance the effectiveness of their online endorsements and identify tactics brands can employ to ensure that the influencers they collaborate with are optimally suited to promote their products

Exploring the parameter space of MagLIF implosions using similarity scaling. I. Theoretical framework

Magneto-inertial fusion (MIF) concepts, such as the Magnetized Liner Inertial Fusion (MagLIF) platform [M. R. Gomez et al., Phys. Rev. Lett. 113, 155003 (2014)], constitute a promising path for achieving ignition and significant fusion yields in the laboratory. The space of experimental input parameters defining a MagLIF load is highly multi-dimensional, and the implosion itself is a complex event involving many physical processes. In the first paper of this series, we develop a simplified analytical model that identifies the main physical processes at play during a MagLIF implosion. Using non-dimensional analysis, we determine the most important dimensionless parameters characterizing MagLIF implosions and provide estimates of such parameters using typical fielded or experimentally observed quantities for MagLIF. We then show that MagLIF loads can be "incompletely" similarity scaled, meaning that the experimental input parameters of MagLIF can be varied such that many (but not all) of the dimensionless quantities are conserved. Based on similarity-scaling arguments, we can explore the parameter space of MagLIF loads and estimate the performance of the scaled loads. In the follow-up papers of this series, we test the similar scaling theory for MagLIF loads against simulations for two different scaling "vectors", which include current scaling and rise-time scaling.Comment: 24 pages, submitted to Physics of Plasma

A framework for experimental-data-driven assessment of Magnetized Liner Inertial Fusion stagnation image metrics

A variety of spherical crystal x-ray imager (SCXI) diagnostics have been developed and fielded on Magnetized Liner Inertial Fusion (MagLIF) experiments at the Sandia National Laboratories Z-facility. These different imaging modalities provide detailed insight into different physical phenomena such as mix of liner material into the hot fuel, cold liner emission, or reduce impact of liner opacity. However, several practical considerations ranging from the lack of a consistent spatial fiducial for registration to different point-spread-functions and tuning crystals or using filters to highlight specific spectral regions make it difficult to develop broadly applicable metrics to compare experiments across our stagnation image database without making significant unverified assumptions. We leverage experimental data for a model-free assessment of sensitivities to instrumentation-based features for any specified image metric. In particular, we utilize a database of historical and recent MagLIF data including $N_{\text{scans}} = 139$ image plate scans gathered across $N_{\text{exp}} = 67$ different experiments to assess the impact of a variety of features in the experimental observations arising from uncertainties in registration as well as discrepancies in signal-to-noise ratio and instrument resolution. We choose a wavelet-based image metric known as the Mallat Scattering Transform for the study and highlight how alternate metric choices could also be studied. In particular, we demonstrate a capability to understand and mitigate the impact of signal-to-noise, image registration, and resolution difference between images. This is achieved by utilizing multiple scans of the same image plate, sampling random translations and rotations, and applying instrument specific point-spread-functions found by ray tracing to high-resolution datasets, augmenting our data in an effectively model-free fashion.Comment: 17 pages, 14 figure

Computer-based concept maps for enabling multilingual education in computer science: A Basque, English and Spanish languages case

Inside the globalisation era in which society is immersed, one of the current challenges for any educational system is to provide quality education. While some countries are linguistically homogeneous, many countries and regions display a wealth of linguistic diversity and it is essential to adapt the educational system to those realities. In addition, multilingual education promotes not only social equality but also inter-cultural education. The development of computer software localisable not only at interface level but also regarding learning resources may help to fulfill this aim. During the last years a number of products have emerged to support computer-based concept mapping. This paper presents a pilot study carried out at the University of the Basque Country UPV/EHU in the area of database systems with three main aims: to facilitate learning about the subject domain, to evaluate whether concept mapping is in general a good technique for learning topics in different languages, and finally, to verify whether CM-ED Concept Map EDitor provides the necessary mechanisms to fulfil this objective. Results confirm that the use of a concept map editor is a good support for education in multilingual settings.Arruarte Lasa, A.; Elorriaga, J.; Calvo, I.; Larrañaga, M.; Rueda Molina, U. (2012). Computer-based concept maps for enabling multilingual education in computer science: A Basque, English and Spanish languages case. Australasian Journal of Educational Technology. 28(5):793-808. doi:10.14742/ajet.81779380828

Exploring the parameter space of MagLIF implosions using similarity scaling. II. Current scaling

Magnetized Liner Inertial Fusion (MagLIF) is a magneto-inertial-fusion (MIF) concept, which is presently being studied on the Z Pulsed Power Facility. The MagLIF platform has achieved interesting plasma conditions at stagnation and produced significant fusion yields in the laboratory. Given the relative success of MagLIF, there is a strong interest to scale the platform to higher peak currents. However, scaling MagLIF is not entirely straightforward due to the large dimensionality of the experimental input parameter space and the large number of distinct physical processes involved in MIF implosions. In this work, we propose a novel method to scale MagLIF loads to higher currents. Our method is based on similarity (or similitude) scaling and attempts to preserve much of the physics regimes already known or being studied on today's Z pulsed-power driver. By avoiding significant deviations into unexplored and/or less well-understood regimes, the risk of unexpected outcomes on future scaled-up experiments is reduced. Using arguments based on similarity scaling, we derive the scaling rules for the experimental input parameters characterizing a MagLIF load (as functions of the characteristic current driving the implosion). We then test the estimated scaling laws for various metrics measuring performance against results of 2D radiation--magneto-hydrodynamic HYDRA simulations. Agreement is found between the scaling theory and the simulation results.Comment: 19 pages, submitted to Physics of Plasma

The highly surprising behaviour of diphosphine ligands in iron-catalysed Negishi cross-coupling

Iron-catalysed cross-coupling is undergoing explosive development, but mechanistic understanding lags far behind synthetic methodology. Here, we find that the activity of iron–diphosphine pre-catalysts in the Negishi coupling of benzyl halides is strongly dependent on the diphosphine, but the ligand does not appear to be coordinated to the iron during turnover. This was determined using time-resolved in operando X-ray absorption fine structure spectroscopy employing a custom-made flow cell and confirmed by 31P NMR spectroscopy. While the diphosphine ligands tested are all able to coordinate to iron(II), in the presence of excess zinc(II)—as in the catalytic reaction—they coordinate predominantly to the zinc. Furthermore, combined synthetic and kinetic investigations implicate the formation of a putative mixed Fe–Zn(dpbz) species before the rate-limiting step of catalysis. These unexpected findings may not only impact the field of iron-catalysed Negishi cross-coupling, but potentially beyond to reactions catalysed by other transition metal/diphosphine complexes

Updating known distribution models for forecasting climate change impact on endangered species

To plan endangered species conservation and to design adequate management programmes, it is necessary to predict their distributional response to climate change, especially under the current situation of rapid change. However, these predictions are customarily done by relating de novo the distribution of the species with climatic conditions with no regard of previously available knowledge about the factors affecting the species distribution. We propose to take advantage of known species distribution models, but proceeding to update them with the variables yielded by climatic models before projecting them to the future. To exemplify our proposal, the availability of suitable habitat across Spain for the endangered Bonelli’s Eagle (Aquila fasciata) was modelled by updating a pre-existing model based on current climate and topography to a combination of different general circulation models and Special Report on Emissions Scenarios. Our results suggested that the main threat for this endangered species would not be climate change, since all forecasting models show that its distribution will be maintained and increased in mainland Spain for all the XXI century. We remark on the importance of linking conservation biology with distribution modelling by updating existing models, frequently available for endangered species, considering all the known factors conditioning the species’ distribution, instead of building new models that are based on climate change variables only.Ministerio de Ciencia e Innovación and FEDER (project CGL2009-11316/BOS