Two-out-of-two color matching based visual cryptography schemes

International audienceVisual cryptography which consists in sharing a secret message between transparencies has been extended to color prints. In this paper, we propose a new visual cryptography scheme based on color matching. The stacked printed media reveal a uniformly colored message decoded by the human visual system. In contrast with the previous color visual cryptography schemes, the proposed one enables to share images without pixel expansion and to detect a forgery as the color of the message is kept secret. In order to correctly print the colors on the media and to increase the security of the scheme, we use spectral models developed for color reproduction describing printed colors from an optical point of view

Fourier-based automatic alignment for improved visual cryptography schemes

International audienceIn Visual Cryptography, several images, called "shadow images", that separately contain no information, are overlapped to reveal a shared secret message. We develop a method to digitally register one printed shadow image acquired by a camera with a purely digital shadow image, stored in memory. Using Fourier techniques derived from Fourier Optics concepts, the idea is to enhance and exploit the quasi periodicity of the shadow images, composed by a random distribution of black and white patterns on a periodic sampling grid. The advantage is to speed up the security control or the access time to the message, in particular in the cases of a small pixel size or of large numbers of pixels. Furthermore, the interest of visual cryptography can be increased by embedding the initial message in two shadow images that do not have identical mathematical supports, making manual registration impractical. Experimental results demonstrate the successful operation of the method, including the possibility to directly project the result onto the printed shadow image

Xylosyltransferase-I Regulates Glycosaminoglycan Synthesis during the Pathogenic Process of Human Osteoarthritis

Loss of glycosaminoglycan (GAG) chains of proteoglycans (PGs) is an early event of osteoarthritis (OA) resulting in cartilage degradation that has been previously demonstrated in both huma and experimental OA models. However, the mechanism of GAG loss and the role of xylosyltransferase-I (XT-I) that initiates GAG biosynthesis onto PG molecules in the pathogenic process of human OA are unknown. In this study, we have characterized XT-I expression and activity together with GAG synthesis in human OA cartilage obtained from different regions of the same joint, defined as “normal”, “late-stage” or adjacent to “late-stage”. The results showed that GAG synthesis and content increased in cartilage from areas flanking OA lesions compared to cartilage from macroscopically “normal” unaffected regions, while decreased in “late-stage” OA cartilage lesions. This increase in anabolic state was associated with a marked upregulation of XT-I expression and activity in cartilage “next to lesion” while a decrease in the “late-stage” OA cartilage. Importantly, XT-I inhibition by shRNA or forced-expression with a pCMV-XT-I construct correlated with the modulation of GAG anabolism in human cartilage explants. The observation that XT-I gene expression was down-regulated by IL-1β and up-regulated by TGF-β1 indicates that these cytokines may play a role in regulating GAG content in human OA. Noteworthy, expression of IL-1β receptor (IL-1R1) was down-regulated whereas that of TGF-β1 was up-regulated in early OA cartilage. Theses observations may account for upregulation of XT-I and sustained GAG synthesis prior to the development of cartilage lesions during the pathogenic process of OA

Chemical and morphological filters in a specialized floral mimicry system

Summary Many plant species attract insect pollinators through chemical mimicry of their oviposition sites, often detaining them in a trap chamber that ensures pollen transfer. These plant mimics are considered to be unspecialized at the pollinator species level, yet field observations of a mycoheterotrophic rainforest orchid (Gastrodia similis), which emits an odour reminiscent of rotting fruit, indicate that it is pollinated by a single drosophilid fly species (Scaptodrosophila bangi). We investigated the roles of floral volatiles and the dimensions of the trap chamber in enforcing this specialization, using gas chromatography-mass spectrometry analyses, bioassays and scanning electron microscopy. We showed that G. similis flowers predominantly emit three fatty-acid esters (ethyl acetate, ethyl isobutyrate and methyl isobutyrate) that were shown in experiments to attract only Scaptodrosophila flies. We additionally showed that the trap chamber, which flies enter into via a touch-sensitive 'trapdoor', closely matches the body size of the pollinator species S. bangi and plays a key role in pollen transfer. Our study demonstrates that specialization in oviposition site mimicry is due primarily to volatile chemistry and is reflected in the dimensions of the trapping apparatus. It also indicates that mycoheterotrophic plants can be specialized both on mycorrhizal fungi and insect pollinators

Community structure of woody plants on islands along a bioclimatic gradient

Peer reviewe

Long-Lasting Inhibitory Effects of Fetal Liver Mesenchymal Stem Cells on T-Lymphocyte Proliferation

Human bone marrow mesenchymal stem cells (BM-MSC) are multipotent progenitor cells that have transient immunomodulatory properties on Natural Killer (NK) cells, Dendritic Cells (DC), and T cells. This study compared the use of MSC isolated from bone marrow and fetal liver (FL-MSC) to determine which displayed the most efficient immunosuppressive effects on T cell activation. Although both types of MSC exhibit similar phenotype profile, FL-MSC displays a much more extended in vitro life-span and immunomodulatory properties. When co-cultured with CD3/CD28-stimulated T cells, both BM-MSC and FL-MSC affected T cell proliferation by inhibiting their entry into the cell cycle, by inducing the down-regulation of phospho-retinoblastoma (pRb), cyclins A and D1, as well as up-regulating p27kip1expression. The T cell inhibition by MSC was not due to the soluble HLA-G5 isoform, but to the surface expression of HLA-G1, as shown by the need of cell-cell contact and by the use of neutralizing anti-HLA-G antibodies. To note, in a HLA-G-mediated fashion, MSC facilitated the expansion of a CD4low/CD8low T subset that had decreased secretion of IFN-γ, and an induced secretion of the immunomodulatory cytokine IL-10. Because of their longer lasting in vitro immunosuppressive properties, mainly mediated by HLA-G, and their more efficient induction of IL-10 production and T cell apoptosis, fetal liver MSC could be considered a new tool for MSC therapy to prevent allograft rejection

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

Meeting abstrac

Combining perspective and color visual cryptography for securing color image display

International audienceIn this work, we propose to extend the secure information display introduced by Yamamoto et al. [1] to full color images. Yamamoto's technique makes use of black and transparent mask as decoding shadow image of a visual cryptography scheme sharing 3 bits multi-color messages. By combining perspective setup together with a color visual cryptography (VC) scheme which does not use any mask, we can securely display color images. A satisfying color VC scheme is used which can be printed on a transparency film. When printed, colors act as filters [2] and allow a wider color gamut for the message which is not limited to saturated color as in [1] because of the black and transparent mask as decoding shadow image. In our implementation of the two-out-of-two visual cryptography scheme which shares a secret message into two color shadow images, the first one is projected onto a glass diffuser and the second one is printed on a transparency. A registration method is used in order to overcome the difficulty of shadow image alignment. As the two shadow images are superposed with an air layer, the message disappears when the angular position is not close to the ideal one. Examples with binary colored messages and with color images are provided to show the extension. By moving the detector (or the eyes) angularly around the right position, perspective effects can be perceived