1,355,418 research outputs found

    Heidmann, A.

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    Que veut et que fait une comparaison différentielle ? Entretien avec Ute Heidmann. Propos recueillis par Jean-Michel Adam & David Martens

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    À la faveur de ses nombreux travaux relatifs aux genres littéraires et non littéraires, aux récits de voyage, aux contes et nouvelles, à l’écriture et à la reconfiguration des mythes gréco-romains, au traduire, à l’écriture de soi et à l’écriture destinée aux jeunes lecteurs, Ute Heidmann a été conduite depuis une dizaine d’années à développer et à formaliser certains principes théoriques et méthodologiques, qu’elle désigne sous l’appellation de « comparai- son différentielle ». Si les principes qui régissent sa démarche s’inscrivent dans les voies du comparatisme littéraire qu’elle s’emploie à rénover, il y avait lieu de se demander dans quelle mesure cette approche peut être utilement mobilisée dans la recherche relative à d’autres domaines que ceux traditionnellement investigués en littérature comparée. Le présent entretien s’emploie ainsi à examiner la place de la comparaison différentielle et certains de ses principaux enjeux en fonction de la rencontre de deux points de vue, celui d’un linguiste, Jean-Michel Adam, qui connaît bien le travail d’Ute Heidmann, avec qui il a collaboré à de multiples reprises, et celui d’un littéraire, David Martens.status: Publishe

    Rev. J. C. F. Heidmann

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    295.H4.34.jpg created from original photograph in the [Van Wijk Rhenish Missionary Society Collection] held in the Manuscripts Section of the Stellenbosch Library and Information Service.Photograph of Rev J. C. F. Heidmann as a young man

    Jean Heidmann (1923-2000) and SETI

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    AbstractJean Heidmann (1923-2000) began his research career as a radio-astronomer in 1959 at Paris Observatory, investigating the structure of galaxies and the distance scale in the nearby universe. In the early 1980's, his scientific interest broadened to the search for extraterrestrial intelligence and he became a strong advocate of SETI, either from the ground or from space.</jats:p

    Optomechanical coupling between ultracold atoms and a membrane oscillator

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    In this thesis, I report on the realization of a hybrid optomechanical system in which ultracold atoms are coupled to a micromechanical membrane. The atoms are trapped in the intensity maxima of an optical standing wave formed by retroreflection of a laser beam from the membrane surface. Vibrations of the membrane displace the standing wave, thus coupling to the center-of-mass motion of the atomic ensemble. Conversely, atoms imprint their motion onto the laser light, thereby modulating the radiation pressure force on the membrane. In this way, the laser light mediates a long-distance, coherent coupling between the two systems. When the trap frequency of the atoms is matched to the membrane frequency, we observe resonant energy transfer. In addition, by applying simultaneous laser cooling to the atoms, we can dissipate energy from the coupled system leading to sympathetic cooling of the membrane mode. The experimental data follows the theoretical estimations that predict the coupling to scale with the number of trapped atoms. Furthermore, by including the finite temperature of the atoms and their spatially inhomogeneous trapping potential in the theoretical model of the optomechanical coupling, we can accurately describe the width and shape of the resonance. In an improved experimental setup, the membrane is enclosed in a cavity while the atoms are trapped in the standing wave lattice outside the cavity. The presence of the cavity results in a considerable enhancement of the coupling strength in proportion to the cavity finesse. So far we have observed sympathetic cooling of the membrane mode by a factor of 32 starting from room temperature. Theoretical estimates show that in such a setup ground-state cooling of the membrane mode should be possible, allowing one to access the quantum coherent coupling regime
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