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La liberté de l’information est un corrélat de la démocratie dont Rousseau pensait qu’elle ne pouvait fonctionner correctement qu’en de petits territoires, préférablement une île – la Corse – pourquoi pas l’Islande ? Que se passe-t-il quand un modèle ancestral est bousculé par Internet et les journaux gratuits

An Imaging Fabry-Perot System for the Robert Stobie Spectrograph on the Southern African Large Telescope

We present the design of the Fabry-Perot system of the Robert Stobie Spectrograph on the 10-meter class Southern African Large Telescope and its characterization as measured in the laboratory. This system provides spectroscopic imaging at any desired wavelength spanning a bandpass 430 - 860 nm, at four different spectral resolving powers ranging from 300 to 9000. Our laboratory tests revealed a wavelength dependence of the etalon gap and parallelism with a maximum variation between 600 - 720 nm that arises because of the complex structure of the broadband multi-layer dielectric coatings. We also report an unanticipated optical effect of this multi-layer coating structure that produces a significant, and wavelength dependent, change in the apparent shape of the etalon plates. This change is caused by two effects: the physical non-uniformities or thickness variations in the coating layers, and the wavelength dependence of the phase change upon refection that can amplify these non-uniformities. We discuss the impact of these coating effects on the resolving power, finesse, and throughput of the system. This Fabry-Perot system will provide a powerful tool for imaging spectroscopy on one of the world's largest telescopes.Comment: 17 pages, 14 figures, accepted for publication in The Astronomical Journa

Transitional B Cells and TLR9 Responses Are Defective in Selective IgA Deficiency.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked FilesSelective IgA deficiency (IgAD) is the most common primary antibody deficiency in the western world with affected individuals suffering from an increased burden of autoimmunity, atopic diseases and infections. It has been shown that IgAD B cells can be induced with germinal center mimicking reactions to produce IgA. However, IgA is the most prevalent antibody in mucosal sites, where antigen-independent responses are important. Much interest has recently focused on the role of TLR9 in both naïve and mature B cell differentiation into IgA secreting plasma cells. Here, we analyze the phenotype and function of T and B cells in individuals with IgAD following IgA-inducing CpG-TLR9 stimulations. The IgAD individuals had significantly lower numbers of transitional B cells (CD19+CD24hiCD38hi) and class-switched memory B cells (CD20+CD27+IgD-) ex vivo. However, proportions of T cell populations ex vivo as well as in vitro induced T effector cells and T regulatory cells were comparable to healthy controls. After CpG stimulation, the transitional B cell defect was further enhanced, especially within its B regulatory subset expressing IL-10. Finally, CpG stimulation failed to induce IgA production in IgAD individuals. Collectively, our results demonstrate a defect of the TLR9 responses in IgAD that leads to B cell dysregulation and decreased IgA production.Icelandic Research Fund University hospital of Iceland research fun

Manufacturing of four-quadrant phase mask for nulling interferometry in the thermal infrared

The Four Quadrant Phase Mask is a key component for the design of advanced coronagraphs that may be used to search exo-planets. The validity of this concept has been demonstrated in the visible and need now to be demonstrated in the mid infrared. For this purpose, two components are manufactured for wavelengths 4.75 and 16.25 μm. This manufacturing requires the deposition of ZnSe layers using Ion Assisted Deposition, followed by a lift off process

Broadband antireflection coatings for visible and infrared ranges

International audienceAntireflection coatings are critical elements for space applications as they will influence the overall performances of optical systems. They are among the most classical elements that are produced with optical coatings but remain a challenge when high performances are required. In this paper, we present some recent results based on thin film technology for the production of antireflection coatings dedicated to visible, near-IR and mid-IR spectral ranges. We first present a theoretical and experimental study of broadband antireflection coatings for [400-1100] nm spectral range. We then show antireflection coatings covering the [1.5-15] µm range. Experimental demonstrations and limitations are presented

High performance thin-film optical filters with stress compensation

International audienceWe present a thorough description of high performance thin-film optical filters with high flatness. These components can combine several tens or hundreds of layers and are manufactured using plasma-assisted reactive magnetron sputtering. Stress compensation is achieved using dual side coatings with appropriate spectral function. Examples of highly reflecting mirrors at 515 nm with 15 nm flatness peak-to-valley over up to 75 mm diameter aperture, narrow bandpass filters and filters with broadband controlled transmission are described

What can a swiped word tell us more? Demographic and behavioral correlates from shape-writing text entry

peer reviewedShape-writing (aka gesture typing or swiping) is a word-based text entry method for touchscreen keyboards. It works by landing the finger on (or close to) the first character of the desired word and then sliding over all the other character keys without lifting the finger until the last word character is reached. This generates a trajectory of swiped characters on the keyboard layout which can be translated to a meaningful word by a statistical decoder. We hypothesize that swiping carries rich information about the user, such as demographic (e.g., age or gender) and behavioral (e.g., swiping familiarity or input finger) information. To test our hypothesis, we trained several sequence classifiers using different recurrent neural network architectures to predict demographic and behavioral correlates of users from swipe trajectories. We show that our sequence classifiers are always performing better than a random classifier; therefore, we conclude that cognitive and motor control mechanisms are embodied and reflected in swipe trajectories, validating thus our research hypothesis. Taken together, our results have implications for user privacy. Currently swiping is supported by all mobile vendors and has millions of users, so people may be inadvertently profiled at an unprecedented granularity. Future work should consider new ways of addressing these issues without impacting the user’s swiping experience

Mapping of Signaling Pathways Linked to sIgAD Reveals Impaired IL-21 Driven STAT3 B-Cell Activation.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked DownloadObjectives: It has recently been shown that individuals with selective IgA deficiency (sIgAD) have defective B cell responses both to T cell dependent and independent mimicking stimulations. The complex intracellular signaling pathways from different stimuli leading to IgA isotype switching have not been fully elucidated. Thus, the main objective of this study was to delineate these pathways and their potential role in the immunopathology linked to sIgAD. Materials and Methods: PBMCs from 10 individuals with sIgAD and 10 healthy controls (HC) were activated in vitro via either a T cell dependent or independent mimicking stimulation. Intracellular phosphorylation of pSTAT3, pSTAT5, pSTAT6, and as pERK1/2 was evaluated in T and B cells using phosphoflow cytometry. Results: By evaluating T cell dependent cytokine driven pathways linked to IgA isotype induction we identified a defect involving an IL-21 driven STAT3 activation isolated to B cells in sIgAD individuals. However, all other signaling pathways studied were found to be normal compared to HC. In T cell dependent cytokine driven stimulations linked to IgA isotype induction the following patterns emerged: (i) IL-10 led to significant STAT3 activation in both T- and B cells; (ii) IL-4 stimulation was predominantly confined to STAT6 activation in both T- and B cells, with some effects on STAT3 activation in T-cells; (iii) as expected, of tested stimuli, IL-2 alone activated STAT5 and some STAT3 activation though in both cases only in T-cells; (iv) IL-21 induced significant activation of STAT3 in both T- and B cells, with some effects on STAT5 activation in T-cells; and finally (v) synergistic effects were noted of IL-4+IL-10 on STAT5 activation in T-cells, and possibly STAT6 in both T- and B cells. On the other hand, CPG induced T cell independent activation was confined to ERK1/2 activation in B cells. Conclusion: Our results indicate a diminished STAT3 phosphorylation following IL-21 stimulation solely in B cells from sIgAD individuals. This can represent aberrant germinal center reactions or developmental halt. Thus, our work provides further insight into the unraveling of the previously hypothesized role of IL-21 to reconstitute immunoglobulin production in primary antibody deficiencies.Icelandic Research Fund University hospital of Iceland research fun