31,834 research outputs found

    CVT/GPL phase 3 integrated testing

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    The hardware for 20 candidate shuttle program life sciences experiments was installed in the GPL and experiments were conducted during a 5-day simulated mission. The experiments involved humans, primates, rats, chickens, and marigold plants. All experiments were completed to the satisfaction of the experimenters. In addition to the scientific data gathered for each experiment, information was obtained concerning experiment hardware design and integration, experiment procedures, GPL support systems, and test operations. The results of the integrated tests are presented

    Multi-view 3D retrieval using silhouette intersection and multi-scale contour representation

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    We describe in this paper two methods for 3D shape indexing and retrieval that we apply on two data collections of the SHREC - SHape Retrieval Contest 2007: Watertight models and 3D CAD models. Both methods are based on a set of 2D multi-views after a pose and scale normalization of the models using PCA and the enclosing sphere. In all views we extract the models silhouettes and compare them pairwise. In the first method the similitude measure is obtained by integrating on the pairs of views the difference between the areas of the silhouettes union and the silhouettes intersection. In the second method we consider the external contour of the silhouettes, extract their convexities and concavities at different scale levels and build a multiscale representation. The pairs of contours are then compared by elastic matching achieved by using dynamic programming. Comparisons of the two methods are shown with their respective strengths and weaknesses

    Canonical Transformation Approach to the Ultrafast Non-linear Optical Dynamics of Semiconductors

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    We develop a theory describing the effects of many-particle Coulomb correlations on the coherent ultrafast nonlinear optical response of semiconductors and metals. Our approach is based on a mapping of the nonlinear optical response of the ``bare'' system onto the linear response of a ``dressed'' system. The latter is characterized by effective time-dependent optical transition matrix elements, electron/hole dispersions, and interaction potentials, which in undoped semiconductors are determined by the single-exciton and two-exciton Green functions in the absence of optical fields. This mapping is achieved by eliminating the optically-induced charge fluctuations from the Hamiltonian using a Van Vleck canonical transformation. It takes into account all many-body contributions up to a given order in the optical fields as well as important Coulomb-induced quantum dynamics to all orders in the optical field. Our approach allows us to distinguish between optical nonlinearities of different origins and provides a physically-intuitive interpretation of their manifestations in ultrafast coherent nonlinear optical spectroscopy.Comment: 24 page

    "Strongly interacting matter in magnetic fields": an overview

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    This is an introduction to the volume of Lecture Notes in Physics on "Strongly interacting matter in magnetic fields". The volume combines contributions written by a number of experts on different aspects of the problem. The response of QCD matter to intense magnetic fields has attracted a lot of interest recently. On the theoretical side, this interest stems from the possibility to explore the plethora of novel phenomena arising from the interplay of magnetic field with QCD dynamics. On the experimental side, the interest is motivated by the recent results on the behavior of quark-gluon plasma in a strong magnetic field created in relativistic heavy ion collisions at RHIC and LHC. The purpose of this introduction is to provide a brief overview and a guide to the individual contributions where these topics are covered in detail.Comment: 12 pages, introduction to "Strongly interacting matter in magnetic fields", Lect. Notes Phys. 871, 1 (2013), edited by D. Kharzeev, K. Landsteiner, A. Schmitt, H.-U. Yee; v2: references update

    Adaptive computing techniques

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    Adaptive local algorithm and convergence speed of multimodal multidimensional functio
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