Phase and compositional analysis of a Sèvres soft paste porcelain plate from 1781, with a review of early porcelain techniques

Optical microscopy, X-ray diffraction, X-ray fluorescence and scanning electron microscopy analyses were carried out on a typical Sèvres soft (frit) porcelain plate from 1781 in order to determine the chemical and mineralogical composition as well as the microstructure of its ceramic body, glaze, overglaze decoration and gilding. The body is rich in SiO₂ (73 mass%), CaO (16) and alkali oxide (8) and shows acicular wollastonite and tridymite crystals embedded in a glassy matrix consisting of SiO₂ (75), K₂O (12) and CaO (9). The 50–90 µm thick, transparent lead glaze (40.9 PbO) contains 47.6 SiO₂, 6.5 K₂O and 3.5 CaO and shows a 35–75 µm thick reaction zone (50 SiO₂, 30 PbO, 14 CaO) towards the body. The maximum thickness of the different paints is 50 µm, with 15 µm as mean thickness of the individual paint stroke. Two blue colours, for the dentil comb and the flower painting, are chemically distinct (colouring CoO in the dental rim 7, in the flower’s blue 2 mass%) and contain many As- and Pb- rich globules and dendrites. Pseudohexagonal shaped platelets of Pb–Sb–Sn triple oxide crystals, embedded in a colourless glassy matrix, generate the opacity and the colour of the yellow paints. Opaque olive green colours are created by the combination of such yellow crystals with a bluish, Cu and Co bearing glassy matrix. The opaque red overglaze enamel is a mechanical mix of yellow Pb–Sb oxide crystals with an iron- rich (16 Fe₂O₃) Pb–silica glass. Purple is very homogeneous and shows tiny drops of pure gold (max. diam. 0.5 µm) in a glassy matrix (47 PbO, 46 SiO₂, 5 K₂O). Violet is a mechanical blend of flower’s blue and purple. The pure (99.5 Au, 0.5 Fe₂O₃) gilt consists of several folded gold particles. The results of this study are only broadly consistent with the archival documented 18th century technologies. The compositional dissimilarities of the studied enamels suggest that each colour was independently fritted. Consequently, the original colour recipes written down by Hellot in 1753 must have been modified in the 30 years since then

Aux quatre coins du monde

Anne d’Albis a été directrice de recherche au CNRS, représentante du CNRS en Afrique du Sud, et directrice adjointe de la Direction des relations internationales. À la retraite depuis l’été 2005, elle nous livre un regard à la fois attendri, passionné et acéré, sur son parcours professionnel et sur l’institution qu’elle a représentée au-delà des frontières

Learning accurate path integration in a ring attractor model of the head direction system

Ring attractor models for angular path integration have recently received strong experimental support. To function as integrators, head-direction (HD) circuits require precisely tuned connectivity, but it is currently unknown how such tuning could be achieved. Here, we propose a network model in which a local, biologically plausible learning rule adjusts synaptic efficacies during development, guided by supervisory allothetic cues. Applied to the Drosophila HD system, the model learns to path-integrate accurately and develops a connectivity strikingly similar to the one reported in experiments. The mature network is a quasi-continuous attractor and reproduces key experiments in which optogenetic stimulation controls the internal representation of heading, and where the network remaps to integrate with different gains. Our model predicts that path integration requires supervised learning during a developmental phase. The model setting is general and also applies to architectures that lack the physical topography of a ring, like the mammalian HD system

DejaVu: Intra-operative Simulation for Surgical Gesture Rehearsal

International audienceAdvances in surgical simulation and surgical augmented reality have changed the way surgeons prepare for practice and conduct medical procedures. Despite considerable interest from surgeons, the use of simulation is still predominantly confined to pre-operative training of surgical tasks and the lack of robustness of surgical augmented reality means that it is seldom used for surgical guidance. In this paper, we present DejaVu, a novel surgical simulation approach for intra-operative surgical gesture rehearsal. With DejaVu we aim at bridging the gap between pre-operative surgical simulation and crucial but not yet robust intra-operative surgical augmented reality. By exploiting intra-operative images we produce a simulation that faithfully matches the actual procedure without visual discrepancies and with an underlying physical modelling that performs real-time deformation of organs and surrounding tissues, surgeons can interact with the targeted organs through grasping, pulling or cutting to immediately rehearse their next gesture. We present results on different in vivo surgical procedures and demonstrate the feasibility of practical use of our system

A reporter mouse for optical imaging of inflammation in mdx muscles

BACKGROUND: Duchenne muscular dystrophy (DMD) is due to mutations in the gene coding for human DMD; DMD is characterized by progressive muscle degeneration, inflammation, fat accumulation, and fibrosis. The mdx mouse model of DMD lacks dystrophin protein and undergoes a predictable disease course. While this model has been a valuable resource for pre-clinical studies aiming to test therapeutic compounds, its utility is compromised by a lack of reliable biochemical tools to quantifiably assay muscle disease. Additionally, there are few non-invasive assays available to researchers for measuring early indicators of disease progression in mdx mice. METHODS: Mdx mice were crossed to knock-in mice expressing luciferase from the Cox2 promoter. These reporter mice (Cox2(FLuc/+)DMD(−/−)) were created to serve as a tool for researchers to evaluate muscle inflammation. Luciferase expression was assayed by immunohistochemistry to insure that it correlated with muscle lesions. The luciferase signal was quantified by optical imaging and luciferase assays to verify that the signal correlated with muscle damage. As proof of principle, Cox2(FLuc/+)DMD(−/−) mice were also treated with prednisolone to validate that a reduction in luciferase signal correlated with prednisone treatment. RESULTS: In this investigation, a novel reporter mouse (Cox2(FLuc/+)DMD(−/−) mice) was created and validated for non-invasive quantification of muscle inflammation in vivo. In this dystrophic mouse, luciferase is expressed from cyclooxygenase 2 (Cox2) expressing cells and bioluminescence is detected by optical imaging. Bioluminescence is significantly enhanced in damaged muscle of exercised Cox2(FLuc/+)DMD(−/−) mice compared to non-exercised Cox2(FLuc/+)DMD(+/+) mice. Moreover, the Cox2 bioluminescent signal is reduced in Cox2(FLuc/+)DMD(−/−) mice in response to a course of steroid treatment. Reduction in bioluminescence is detectable prior to measurable therapy-elicited improvements in muscle strength, as assessed by traditional means. Biochemical assay of luciferase provides a second means to quantify muscle inflammation. CONCLUSIONS: The Cox2(FLuc/+)DMD(−/−) mouse is a novel tool to evaluate the therapeutic benefits of drugs intended to target inflammatory aspects of dystrophic pathology. This mouse model will be a useful adjunct to traditional outcome measures in assessing potential therapeutic compounds

Neurolinguistics Research Advancing Development of a Direct-Speech Brain-Computer Interface

A direct-speech brain-computer interface (DS-BCI) acquires neural signals corresponding to imagined speech, then processes and decodes these signals to produce a linguistic output in the form of phonemes, words, or sentences. Recent research has shown the potential of neurolinguistics to enhance decoding approaches to imagined speech with the inclusion of semantics and phonology in experimental procedures. As neurolinguistics research findings are beginning to be incorporated within the scope of DS-BCI research, it is our view that a thorough understanding of imagined speech, and its relationship with overt speech, must be considered an integral feature of research in this field. With a focus on imagined speech, we provide a review of the most important neurolinguistics research informing the field of DS-BCI and suggest how this research may be utilized to improve current experimental protocols and decoding techniques. Our review of the literature supports a cross-disciplinary approach to DS-BCI research, in which neurolinguistics concepts and methods are utilized to aid development of a naturalistic mode of communication. : Cognitive Neuroscience; Computer Science; Hardware Interface Subject Areas: Cognitive Neuroscience, Computer Science, Hardware Interfac