A geoscience perspective on immersive 3D gridded data visualization

We describe visualization software, Visualizer, that was developed specifically for interactive, visual exploration in immersive virtual reality (VR) environments. Visualizer uses carefully optimized algorithms and data structures to support the high frame rates required for immersion and the real-time feedback required for interactivity. As an application developed for VR from the ground up, Visualizer realizes benefits that usually cannot be achieved by software initially developed for the desktop and later ported to VR. However, Visualizer can also be used on desktop systems (unix/linux-based operating systems including Mac OS X) with a similar level of real-time interactivity, bridging the “software gap” between desktop and VR that has been an obstacle for the adoption of VR methods in the Geosciences. While many of the capabilities of Visualizer are already available in other software packages used in a desktop environment, the features that distinguish Visualizer are: (1) Visualizer can be used in any VR environment including the desktop, GeoWall, or CAVE, (2) in non-desktop environments the user interacts with the data set directly using a wand or other input devices instead of working indirectly via dialog boxes or text input, (3) on the desktop, Visualizer provides real-time interaction with very large data sets that cannot easily be viewed or manipulated in other software packages. Three case studies are presented that illustrate the direct scientific benefits realized by analyzing data or simulation results with Visualizer in a VR environment. We also address some of the main obstacles to widespread use of VR environments in scientific research with a user study that shows Visualizer is easy to learn and to use in a VR environment and can be as effective on desktop systems as native desktop applications.     

Exploring Energy Efficient Architectures for RLWE Lattice-Based Cryptography

Journal of Signal Processing Systems - Quantum computers are imminent threat to secure signal processing because they can break the contemporary public-key cryptography schemes in polynomial time....     

Porous Porphyrin‐Based Organosilica Nanoparticles for NIR Two‐Photon Photodynamic Therapy and Gene Delivery in Zebrafish

Periodic mesoporous organosilica nanoparticles emerge as promising vectors for nanomedicine applications. Their properties are very different from those of well‐known mesoporous silica nanoparticles as there is no silica source for their synthesis. So far, they have only been synthesized from small bis‐silylated organic precursors. However, no studies employing large stimuli‐responsive precursors have been reported on such hybrid systems yet. Here, the synthesis of porphyrin‐based organosilica nanoparticles from a large octasilylated metalated porphyrin precursor is described for applications in near‐infrared two‐photon‐triggered spatiotemporal theranostics. The nanoparticles display unique interconnected large cavities of 10–80 nm. The framework of the nanoparticles is constituted with J‐aggregates of porphyrins, which endows them with two‐photon sensitivity. The nanoparticle efficiency for intracellular tracking is first demonstrated by the in vitro near‐infrared imaging of breast cancer cells. After functionalization of the nanoparticles with aminopropyltriethoxysilane, two‐photon‐excited photodynamic therapy in zebrafish is successfully achieved. Two‐photon photochemical internalization in cancer cells of the nanoparticles loaded with siRNA is also performed for the first time. Furthermore, siRNA targeting green fluorescent protein complexed with the nanoparticles is delivered in vivo in zebrafish embryos, which demonstrates the versatility of the nanovectors for biomedical applications.     

The effects of various carbon derivative additives on the thermal properties of paraffin as a phase change material

The storage of thermal energy in phase change materials (PCMs) has found wide applications that enable energy conservation and management. Paraffin is a major PCM with its low cost, wide availability, and relatively high latent heat, yet its low thermal conductivity may become a drawback in high‐power applications. In this study, composites of paraffin were prepared with multiwalled carbon nanotubes and activated carbon by a dispersion technique to overcome these drawbacks. Thermal, chemical, and physical influences of incorporating carbon additives with varying structures in paraffin composites on thermal storage capacity were determined. Results indicated that the thermal conductivities of paraffin‐activated carbon composites (PACC) and paraffin multiwalled carbon nanotube composites (PCNC) were improved by a factor of 39.1 and 34.1%, respectively, compared with the conductivity of pure paraffin. As a bonus, the thermal energy storage capacities of PCNCs were enhanced by 9.6%, whereas this remained unchanged for PACCs. Copyright © 2015 John Wiley & Sons, Ltd.     

Modelling and back-analysing failures in steep limestone cliffs

The observation of 12 rock fall scars in steep limestone cliffs has shown that the fallen masses were stable as a result of relatively small rock bridges. These results demonstrate that consideration of rock bridges is necessary for a realistic evaluation of stability. Limit equilibrium methods of analysis are presented for sliding and toppling, for both isostatic and hyperstatic conditions. These methods are illustrated with four case histories. The results of nine back-analyses of rock falls with volumes between 24 and 3500 m³ are presented. The rock cohesion obtained from back-analysis appears to be significantly lower than the cohesion obtained from classical laboratory tests. This discrepancy can be attributed to several factors including: a spatial and temporal scale effect, the oversimplified modelling (two-dimensional limit equilibrium) and some uncertainties affecting the geometrical data. When analysing the stability of a cliff with a limit equilibrium method, the authors suggest dividing the cohesion by a “scale and method” factor of 3.     

N'-nitro-N-(2,2,2–trinitroethyl) guanidine

The previously reported compound N-nitro-N'-(2,2,2-trinitroethyl) guanidine (3) is shown by ¹H NMR spectroscopy to be actually the corresponding nitrimine tautomer N''-nitro-N-(2,2,2-trinitroethyl) guanidine (4).     

Effects of fish farming on flavonoids in Posidonia oceanica

This work is a first approach to flavonoid responses (total proanthocyanidins and total and simple flavonols) in Posidonia oceanica in function of nutrient enrichment (aquaculture activities - fish farming), in the western Mediterranean Sea (Calvi-Corsica-France). The first result is the presence of total and simple flavonoids in P. oceanica. The second result shows an increase in total proanthocyanidin and total flavonol concentrations near cages, which would be linked to the high grazing pressure induced by meadow enrichment. Concerning simple flavonols, only quercetin shows a response to fish farming, which could be due to its strong antioxidant capacity. The presence of fish farming, which causes variations in environmental parameters, could affect the functioning of P. oceanica meadows. Flavonoid concentrations in P. oceanica seem to be a possible bioindicator of nutrient enrichment for the management of the littoral environment.     

Application of magnetic iron oxide nanoparticles prepared from microemulsions for protein purification

BACKGROUND: Magnetic nanoparticles are of immense interest for their applications in biotechnology. This paper reports the synthesis of magnetic iron oxide nanoparticles from two different water‐in‐oil microemulsion systems (ME‐MIONs), their characterization and also their use in purification of coagulant protein. RESULTS: ME‐MIONs have demonstrated to be an efficient binder in the purification of Moringa oleifera protein when compared with the superparamagnetic iron oxide nanoparticles prepared from coprecipitation in aqueous media. The size and morphology of the ME‐MIONs were studied by transmission electron microscopy (TEM) while the structural characteristics were studied by X‐ray diffraction (XRD). The microemulsion magnetic iron oxide nanoparticles (ME 1‐MION and ME 2‐MION) obtained have a size range 7–10 nm. The protein and ME‐MIONs interaction was investigated by Fourier transform infrared spectroscopy (FT‐IR); the presence of three peaks at 2970, 2910 and 2870 cm^?1 respectively, confirms the binding of the protein. The purification and molecular weight of the coagulant protein was 6.5 kDa as analyzed by SDS‐PAGE. CONCLUSION: The ME‐MIONs have the advantage of being easily tailored in size, are highly efficient as well as magnetic, cost effective and versatile; they are, thus, very suitable for use in a novel purification technique for protein or biomolecules that possess similar characteristics to the Moringa oleifera coagulant protein. Copyright © 2011 Society of Chemical Industry     

Caractérisation d'une pratique d'enseignement des mathématiques : Le cours dialogué

Résumé

L'objet de cet article est de caractériser une pratique d'enseignement des mathématiques que nous nommons cours dialogué, observée dans des classes ordinaires à la fin du collège en France (élèves de 13 à 15 ans) et que nous pensons plus largement utilisée. Pour cela, différentes composantes du contrat didactique sont utilisées en association avec une étude des interactions didactiques observées dans la classe. La méthode d'étude et les composantes du contrat didactique ainsi que les variables des interactions utilisées sont présentées dans les paragraphes 2 et 3 de l'article. Ensuite, ces outils sont utilisés pour analyser une séquence sur la proportionnalité, ce qui permet de dégager les caractéristiques du cours dialogué, notamment en termes de contrat didactique et de fonctions des interactions, par comparaison avec d'autres types d'enseignement mieux connus, la transmission directe du savoir et la transmission du savoir par des situations.