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Bagel

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H Muther – 1st expert on this subject based on the ideXlab platform

  • correlations in nuclei self consistent treatment and the Bagel approach
    Physics Letters B, 1993
    Co-Authors: H Muther, L D Skouras

    Abstract:

    Abstract An approach is presented which allows a self-consistent description of the fragmentation of single-particle strength for nucleons in finite nuclei employing the Green function formalism. The self-energy to be considered in the Dyson equation for the single-particle Green function contains all terms of first (Hartree-Fock) and second order in the residual interaction. It is demonstrated that the fragmentation of the single-particle strength originating from the terms of second order can efficiently be described in terms of the so-called Bagel approximation. Employing this approximation the self-energy can be evaluated in a self-consistent way, i.e. the correlations contained in the Green function are taken into account for the evaluation of the self-energy. As an example this scheme is applied to the nucleus 16 O, using a realistic nucleon nucleon interaction. The effects of the correlations on the occupation probabilities and the binding energy are evaluated.

  • effective interaction derived from the Bagel approach
    Nuclear Physics, 1990
    Co-Authors: L D Skouras, H Muther

    Abstract:

    Abstract Matrix inversion techniques are used to derive an effective hamiltonian for shell-model calculations, which accounts for correlations outside the shell-model space. It is demonstrated that the Bagel approach leads to a very powerful tool to account for the effects of large Q -spaces in a reliable way. An energy-dependent formulation yields stable results even for cases which are divergent in the perturbative approach due to the presence of intruder states. A first application employing modern one-boson exchange potentials produces results which are in very satisfactory agreement with empirical data.

L D Skouras – 2nd expert on this subject based on the ideXlab platform

  • correlations in nuclei self consistent treatment and the Bagel approach
    Physics Letters B, 1993
    Co-Authors: H Muther, L D Skouras

    Abstract:

    Abstract An approach is presented which allows a self-consistent description of the fragmentation of single-particle strength for nucleons in finite nuclei employing the Green function formalism. The self-energy to be considered in the Dyson equation for the single-particle Green function contains all terms of first (Hartree-Fock) and second order in the residual interaction. It is demonstrated that the fragmentation of the single-particle strength originating from the terms of second order can efficiently be described in terms of the so-called Bagel approximation. Employing this approximation the self-energy can be evaluated in a self-consistent way, i.e. the correlations contained in the Green function are taken into account for the evaluation of the self-energy. As an example this scheme is applied to the nucleus 16 O, using a realistic nucleon nucleon interaction. The effects of the correlations on the occupation probabilities and the binding energy are evaluated.

  • effective interaction derived from the Bagel approach
    Nuclear Physics, 1990
    Co-Authors: L D Skouras, H Muther

    Abstract:

    Abstract Matrix inversion techniques are used to derive an effective hamiltonian for shell-model calculations, which accounts for correlations outside the shell-model space. It is demonstrated that the Bagel approach leads to a very powerful tool to account for the effects of large Q -spaces in a reliable way. An energy-dependent formulation yields stable results even for cases which are divergent in the perturbative approach due to the presence of intruder states. A first application employing modern one-boson exchange potentials produces results which are in very satisfactory agreement with empirical data.

M Ugur D Uygunoglu – 3rd expert on this subject based on the ideXlab platform

  • myelopathy in behcet s disease the Bagel sign
    Annals of Neurology, 2017
    Co-Authors: M Ugur D Uygunoglu, M Burcu D Zeydan, M Yesim D Ozguler, M Serdal D Ugurlu, M Emire D Seyahi, M Naci D Kocer, M Civan D Islak, M Kejal D Kantarci, M Sabahattin D Saip

    Abstract:

    Objective: To describe the clinical and distinctive imaging features of myelopathy associated with Behcet’s disease.

    Methods: We evaluated the records of patients meeting the following criteria: a) fulfillment of the International Study Group criteria for Behcet’s disease; b) clinically suggestive of myelopathy; c) simultaneous spinal cord and brain MRIs within 1 month of acute worsening of myelopathy; d) follow-up duration ≥1 year after initial MRI evaluation. Patients not fulfilling all inclusion criteria and having MRIs with poor quality or missing sequences were excluded.

    Results: In 11 patients (9 men, 2 women), we studied 14 MRIs during distinct myelopathy episodes and 9 follow-up MRIs. Two distinct MRI patterns of spinal cord involvement were described according to T2W axial images: 1) “Bagel Sign” pattern: A central lesion with hypo-intense core and hyper-intense rim with or without contrast enhancement; 2) “Motor Neuron” pattern: A symmetric involvement of the anterior horn cells. “Bagel Sign” was present in 13 of 14 myelopathy episodes whereas “Motor Neuron” pattern was observed in 1 of 14 MRIs. Of the 13 MRIs with “Bagel Sign” long myelopathy (n=9), both long and short myelopathy (n=2), and short myelopathy (n=2) was observed. All patterns cleared with some residual lesions after steroid use and immunomodulation with associated clinical recovery in patients.

    Interpretation: The signal characteristics of the “Bagel Sign” potentially represent venous engorgement and/or acute blood products within the spinal cord. To our knowledge, “Bagel Sign” has not been observed in other forms of longitudinal myelopathy outside of BD including neuromyelitis optica. This article is protected by copyright. All rights reserved.