935 research outputs found
Non-reciprocal transmission via phase conjugation in multimode optical fibres
Full text linkWe demonstrate phase conjugate correction of modal distortion of a single mode beam on double-passing a passive highly multimode fibre. Phase conjugation is achieved in a self-pumped photorefractive BaTiO3 crystal which conjugates only the e-polarised input component. We show that only a small fraction of the multimode fibre output is required to faithfully conjugate the single mode input beam. This technique enables the demonstration of a novel non-reciprocal transmission device, which for example has immediate application in gain-grating holographic resonator designs with multimode fibres as the active gain medium
There’s Something about Marine: Strategies against the Far Right in the 2017 French Presidential Elections
No full textThis is the author accepted manuscript.The Front National (FN) achieved unprecedented success in the 2017 French presidential elections, which poses a significant challenge for how competitors against the far right could counter its appeal. Taking as a starting point the existing literature on mainstream party strategies with regard to the far right, this article develops a novel approach. It draws on the insights of positioning theory to analyse a total of 108 speeches and interviews in which the four main candidates to the French Presidency in the 2017 campaign talk about the far right. We find significant variation in candidates' patterns of discourse, but also establish that these distinct strategies are better understood as complex hybrids of the categories in the literature
Henri Matisse Drawing: An Eye-Hand Interaction Study Based on Archival Film.
Full text linkHenri Matisse (1869-1954) attached fundamental importance to his drawings, in particular to the famous Themes et Variations series. These were accomplished following a precise method, starting with arduous life studies and evolving into brilliant spontaneous drawings. A 1946 archival documentary film showing the artist drawing four portraits of his grandson Gerard was shot in such a way as to allow the present author to undertake a detailed eye-hand interaction analysis of the drawing process.
It was found that Matisse’s temporal working rhythm and use of motor memory resulted in a more direct approach than that used by most painters. Taken together with remarks the artist made throughout his lifetime, these results provide a cognitive interpretation of his drawing method
Polyglutamine aggregate structure in vitro and in vivo; new avenues for coherent anti-Stokes Raman scattering microscopy
Full text linkCoherent anti-Stokes Raman scattering (CARS) microscopy is applied for the first time for the evaluation of the protein secondary structure of polyglutamine (polyQ) aggregates in vivo. Our approach demonstrates the potential for translating information about protein structure that has been obtained in vitro by X-ray diffraction into a microscopy technique that allows the same protein structure to be detected in vivo. For these studies, fibres of polyQ containing peptides (D2Q15K2) were assembled in vitro and examined by electron microscopy and X-ray diffraction methods; the fibril structure was shown to be cross β-sheet. The same polyQ fibres were evaluated by Raman spectroscopy and this further confirmed the β-sheet structure, but indicated that the structure is highly rigid, as indicated by the strong Amide I signal at 1659 cm-1. CARS spectra were simulated using the Raman spectrum taking into account potential non-resonant contributions, providing evidence that the Amide I signal remains strong, but slightly shifted to lower wavenumbers. Combined CARS (1657 cm-1) and multi-photon fluorescence microscopy of chimeric fusions of yellow fluorescent protein (YFP) with polyQ (Q40) expressed in the body wall muscle cells of Caenorhabditis elegans nematodes (1 day old adult hermaphrodites) revealed diffuse and foci patterns of Q40-YFP that were both fluorescent and exhibited stronger CARS (1657 cm-1) signals than in surrounding tissues at the resonance for the cross β-sheet polyQ in vitro
In planta imaging of Δ9-tetrahydrocannabinolic acid in Cannabis sativa L. with hyperspectral coherent anti-Stokes Raman scattering microscopy
Full text linkNature has developed many pathways to produce medicinal products of extraordinary potency and specificity with significantly higher efficiencies than current synthetic methods can achieve. Identification of these mechanisms and their precise locations within plants could substantially increase the yield of a number of natural pharmaceutics. We report label-free imaging of Δ9 -tetrahydrocannabinolic acid (THCa) in Cannabis sativa L. using coherent anti-Stokes Raman scattering microscopy. In line with previous observations we find high concentrations of THCa in pistillate flowering bodies and relatively low amounts within flowering bracts. Surprisingly, we find differences in the local morphologies of the THCa-containing bodies: organelles within bracts are large, diffuse, and spheroidal, whereas in pistillate flowers they are generally compact, dense, and have heterogeneous structures. We have also identified two distinct vibrational signatures associated with THCa, both in pure crystalline form and within Cannabis plants; at present the exact natures of these spectra remain an open question.<br/
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