2,215 research outputs found

    A window to the Galactic X-ray halo: The ISM towards the Lockman hole

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    We present a combined X-ray/HI-analysis of the ISM towards the Lockman hole. This sky region is considered as the "window to the distant universe" because of its absolute lowest HI column density on the whole sky. The Lockman hole appears to be not as transparent as the HI data suggest. We propose that about half of the ISM towards the Lockman hole is in form of ionized hydrogen rather than HI.Comment: Proceedings, International Workshop on X-RAY SURVEYS, in the light of new observatories Santander (Spain), 4-6 September 2000 (accepted

    A First Derivative Potts Model for Segmentation and Denoising Using ILP

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    Unsupervised image segmentation and denoising are two fundamental tasks in image processing. Usually, graph based models such as multicut are used for segmentation and variational models are employed for denoising. Our approach addresses both problems at the same time. We propose a novel ILP formulation of the first derivative Potts model with the â„“1\ell_1 data term, where binary variables are introduced to deal with the â„“0\ell_0 norm of the regularization term. The ILP is then solved by a standard off-the-shelf MIP solver. Numerical experiments are compared with the multicut problem.Comment: 6 pages, 2 figures. To appear at Proceedings of International Conference on Operations Research 2017, Berli

    Programmable digital modem

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    Information on programmable digital modems (PDM) is given in viewgraph form. Topics covered include data rate range and operational modes, test and demonstration equipment, program goals, modulation formats, and PDM design challenges

    Social uncertainty is heterogeneous and sometimes valuable

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    To win friends, help the needy, avoid exploitation or influence strangers, people must make decisions that are inherently uncertain. In their compelling and insightful perspective on resolving social uncertainty1, FeldmanHall and Shenhav (henceforth F&S) join a growing movement combining computational approaches with social psychological theory. F&S identify a range of negative and positive aspects of social uncertainty. Here we offer additional ways to think about social uncertainty and suggest potential avenues for future research

    Exchange and correlation energies of ground states of atoms and molecules in strong magnetic fields

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    Using a Hartree-Fock mesh method and a configuration interaction approach based on a generalized Gaussian basis set we investigate the behaviour of the exchange and correlation energies of small atoms and molecules, namely th e helium and lithium atom as well as the hydrogen molecule, in the presence of a magnetic field covering the regime B=0-100a.u. In general the importance of the exchange energy to the binding properties of at oms or molecules increases strongly with increasing field strength. This is due to the spin-flip transitions and in particular due to the contributions of the tightly bound hydrogenic state s which are involved in the corresponding ground states of different symmetries. In contrast to the exchange energy the correlation energy becomes less relevant with increasing field strength. This holds for the individual configurations constituting the ground state and for the crossovers of the global ground state.Comment: 4 Figures acc.f.publ.in Phys.Rev.
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