57,169 research outputs found

    Further application of a semi-microscopic core-particle coupling method to the properties of Gd155,157, and Dy159

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    In a previous paper a semi-microscopic core-particle coupling method that includes the conventional strong coupling core-particle model as a limiting case, was applied to spectra and electromagnetic properties of several well-deformed odd nuclei. This work, coupled a large single-particle space to the ground state bands of the neighboring even cores. In this paper, we generalize the theory to include excited bands of the cores, such as beta and gamma bands, and thereby show that the resulting theory can account for the location and structure of all bands up to about 1.5 MeV.Comment: 15 pages including 9 figure(postscript), submitted to Phys.Rev.

    Polarization characteristics of the Crab pulsar's giant radio pulses at HFCs phases

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    We discuss our recent discovery of the giant radio emission from the Crab pulsar at its high frequency components (HFCs) phases and show the polarization characteristic of these pulses. This leads us to a suggestion that there is no difference in the emission mechanism of the main pulse (MP), interpulse (IP) and HFCs. We briefly review the size distributions of the Crab giant radio pulses (GRPs) and discuss general characteristics of the GRP phenomenon in the Crab and other pulsars.Comment: AIP Conference Proceedings "Astrophysical Sources of High Energy Particles and Radiation", eds. T. Bulik et al. (NY:AIP), Volume 801, 2005, pp. 324-32

    Comparison of giant radio pulses in young pulsars and millisecond pulsars

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    Pulse-to-pulse intensity variations are a common property of pulsar radio emission. For some of the objects single pulses are often 10-times stronger than their average pulse. The most dramatic events are so-called giant radio pulses (GRPs). They can be thousand times stronger than the regular single pulses from the pulsar. Giant pulses are a rare phenomenon, occurring in very few pulsars which split into two groups. The first group contains very young and energetic pulsars like the Crab pulsar, and its twin (PSR B0540-69) in the Large Magellanic Cloud (LMC), while the second group is represented by old, recycled millisecond pulsars like PSR B1937+21, PSR B1821-24, PSR B1957+20 and PSR J0218+4232 (the only millisecond pulsar detected in gamma-rays). We compare the characteristics of GRPs for these two pulsar groups. Moreover, our latest findings of new features in the Crab GRPs are presented. Analysis of our Effelsberg data at 8.35 GHz shows that GRPs do occur in all phases of its ordinary radio emission, including the phases of the two high frequency components (HFCs) visible only between 5 and 9 GHz.Comment: Proceedings of the 363. WE-Heraeus Seminar on: Neutron Stars and Pulsars (Posters and contributed talks) Physikzentrum Bad Honnef, Germany, May.14-19, 2006, eds. W.Becker, H.H.Huang, MPE Report 291, pp.64-6

    Exploring Human Vision Driven Features for Pedestrian Detection

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    Motivated by the center-surround mechanism in the human visual attention system, we propose to use average contrast maps for the challenge of pedestrian detection in street scenes due to the observation that pedestrians indeed exhibit discriminative contrast texture. Our main contributions are first to design a local, statistical multi-channel descriptorin order to incorporate both color and gradient information. Second, we introduce a multi-direction and multi-scale contrast scheme based on grid-cells in order to integrate expressive local variations. Contributing to the issue of selecting most discriminative features for assessing and classification, we perform extensive comparisons w.r.t. statistical descriptors, contrast measurements, and scale structures. This way, we obtain reasonable results under various configurations. Empirical findings from applying our optimized detector on the INRIA and Caltech pedestrian datasets show that our features yield state-of-the-art performance in pedestrian detection.Comment: Accepted for publication in IEEE Transactions on Circuits and Systems for Video Technology (TCSVT

    Possible solution of the Coriolis attenuation problem

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    The most consistently useful simple model for the study of odd deformed nuclei, the particle-rotor model (strong coupling limit of the core-particle coupling model) has nevertheless been beset by a long-standing problem: It is necessary in many cases to introduce an ad hoc parameter that reduces the size of the Coriolis interaction coupling the collective and single-particle motions. Of the numerous suggestions put forward for the origin of this supplementary interaction, none of those actually tested by calculations has been accepted as the solution of the problem. In this paper we seek a solution of the difficulty within the framework of a general formalism that starts from the spherical shell model and is capable of treating an arbitrary linear combination of multipole and pairing forces. With the restriction of the interaction to the familiar sum of a quadrupole multipole force and a monopole pairing force, we have previously studied a semi-microscopic version of the formalism whose framework is nevertheless more comprehensive than any previously applied to the problem. We obtained solutions for low-lying bands of several strongly deformed odd rare earth nuclei and found good agreement with experiment, except for an exaggerated staggering of levels for K=1/2 bands, which can be understood as a manifestation of the Coriolis attenuation problem. We argue that within the formalism utilized, the only way to improve the physics is to add interactions to the model Hamiltonian. We verify that by adding a magnetic dipole interaction of essentially fixed strength, we can fit the K=1/2 bands without destroying the agreement with other bands. In addition we show that our solution also fits 163Er, a classic test case of Coriolis attenuation that we had not previously studied.Comment: revtex, including 7 figures(postscript), submitted to Phys.Rev.
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