The Case for Haptic Props: Shape, Weight and Vibro-tactile Feedback

The use of haptic props in a virtual environment setting is purported to improve both user immersion and task performance. While the efficacy of various forms of haptics has been tested through user experiments, this is not the case for hand-held tool props, an important class of input device with both gaming and non-gaming applications. From a cost and complexity of implementation perspective it is also worth investigating the relative benefits of the different types of passive and active haptics that can be incorporated into such props. Accordingly, in this paper we present the results of a quantitative user experiment (n = 42) designed to assess a typical VR controller against passive, weighted, and active-haptic versions of a tracked prop, measured according to game experience, performance, and stance adopted by participants. The task involved playing a VR baseball game and the prop was a truncated baseball bat. We found a statistically significant improvement (at alpha = 0.05) with medium to large effect size (r > 0.38) for certain aspects of game experience (competence, immersion, flow, positive affect), performance (mean hit distance) and pose (two-handed grip) for the weighted prop over a generic controller, and in many cases over the unweighted passive prop as well. There was no significant difference between our weighted prop and the active-haptic version. This suggests that, for batting and striking tasks, tool props with passive haptics improve user experience and task performance but only if they match the weight of the original real-world tool, and that such weighting is more important than simple vibro-tactile style force-feedback

Geant4-DNA simulations using complex DNA geometries generated by the DnaFabric tool

International audienceSeveral DNA representations are used to study radio-induced complex DNA damages depending on the approach and the required level of granularity. Among all approaches, the mechanistic one requires the most resolved DNA models that can go down to atomistic DNA descriptions. The complexity of such DNA models make them hard to modify and adapt in order to take into account different biological conditions. The DnaFabric project was started to provide a tool to generate, visualise and modify such complex DNA models. In the current version of DnaFabric, the models can be exported to the Geant4 code to be used as targets in the Monte Carlo simulation. In this work, the project was used to generate two DNA fibre models corresponding to two DNA compaction levels representing the hetero and the euchromatin. The fibres were imported in a Geant4 application where computations were performed to estimate the influence of the DNA compaction on the amount of calculated DNA damage. The relative difference of the DNA damage computed in the two fibres for the same number of projectiles was found to be constant and equal to 1.3 for the considered primary particles (protons from 300 keV to 50 MeV). However, if only the tracks hitting the DNA target are taken into account, then the relative difference is more important for low energies and decreases to reach zero around 10 MeV. The computations were performed with models that contain up to 18,000 DNA nucleotide pairs. Nevertheless, DnaFabric will be extended to manipulate multi-scale models that go from the molecular to the cellular levels. © 2016 Elsevier B.V. All rights reserved

Nanostructured Al-based fluoride-oxide materials with core-shell morphology

The investigation of the thermal behavior of β-AlF2.6OH0.4 compound which adopts the hexagonal tungsten bronze network shows that this structure is stable up to 873 K. As revealed by a detailed analysis combining high resolution transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and 19F and 27Al MAS NMR, the sample annealed at 873 K exhibits an unusual core−shell like morphology. The shell which is amorphous contains some AlO6, AlO5, and AlO4 species which have been identified and quantified by 27Al NMR. Contrarily, the core part of the material is crystallized and has been identified as a phase closely related to the hydroxyl free compound β-AlF3 in agreement with the dehydroxylation process. The annealing treatment lowers the Lewis acidity, but strong Brønsted acid sites have been created as evidenced by pyridine adsorption. These strong Brønsted sites arise from the reaction between water and strongly under-coordinated species formed upon annealing. It should be pointed out that such core−shell morphology had never been observed in fluoride or oxide-fluoride systems, so far