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  • 11
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 12
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 13
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 14
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The neutron transfer in a very heavy asymmetric nuclear system, in 206 Pb + 118 Sn has been measured using particle- $\gamma$ coincidence techniques with position-sensitive detectors, 5 EUROBALL-Cluster detectors (EB) and the Heidelberg-Darmstadt NaI-CRYSTAL BALL (CB). The fragments are identified via the known $\gamma$ -decays of the lowest excited states using the high resolution of EB. Using the unique feature of the set-up with the CB, transfer to well-defined final channels with known quantum numbers is selected using the high-efficiency multiplicity filter of the CB with no second $\gamma$ -ray, i.e. without feeding. The enhancement in the two-neutron transfer is deduced, for population of the low-lying super-fluid 2 + states in 120 Sn and 116 Sn, while the 2n-transition remains in the ground state for the recoiling 20X Pb-nuclei. Large enhancements up to EF $\simeq 10^3$ are observed. This is the first observation of neutron pair-transfer enhancement for a heavy nuclear binary system with superfluid properties with experimentally separated levels.
    Type of Medium: Electronic Resource
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  • 15
    ISSN: 1432-2277
    Keywords: Key words Extracellular matrix ; Liver transplantation ; Acute rejection ; Early chronic rejection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have previously observed changes at the extracellular matrix (ECM) which significantly correlated with the extent of preservation and reperfusion injury. In the present study, we attempted to investigate whether the ECM may be also involved in the pathophysiological sequelae of acute and chronic rejection. Of 81 patients monitored for the ECM parameters laminin, hyaluronic acid, fibronectin receptor, and transforming growth factor (TGF)-β , 28 patients developed acute rejection (〈 1 month), in 14 patients (17.4 %) acute rejection was steroid resistant, 4 patients (4.5 %) developed early chronic rejection following acute steroid-resistant rejection. Acute and chronic rejection were confirmed by established clinical and histological criteria. Laminin levels were significantly increased in patients experiencing acute steroid-resistant rejection (4204 ± 133 ng/ml; P K 0.01) compared with patients with steroid-sensitive rejection (1059 ± 27.3 ng/ml) and with an uneventful postoperative course (1214 ± 17.4 ng/ml). No increase in laminin was observed in those four patients who developed early chronic rejection (1099 ± 58.7 ng/ml). Hyaluronic acid, fibronectin receptor, and TGF-β levels also increased in patients with acute steroid-resistant rejection; hyaluronic acid: 290 ± 10.8 μg/l vs 154 ± 13.6 μg/l and 131 ± 11.7 μg/l in patients with steroid-sensitive and no rejection, respectively; fibronectin receptor: 1003 ± 23.5 ng/ml vs 573 ± 24.8 ng/ml and 428 ± 13.6 ng/ml in patients with steroid-sensitive and no rejection, respectively; and TGF-β : 393 ± 14.9 pg/ml versus 315 ± 10.7 pg/ml and 233 ± 8.9 pg/ml in patients with steroid-sensitive and no rejection, respectively. A further increase in hyaluronic acid levels was observed in patients who developed early chronic rejection, while fibronectin receptor and TGF-β levels remained low, similarly to laminin levels. The increase in laminin, hyaluronic acid, fibronectin receptor, and TGF-β during acute steroid-resistant rejection may be stimulated by the rejection-related release of cytokines and adhesion molecules which paralleled the increase in ECM parameters. The lack of increase in laminin and fibronectin receptor levels in those patients who developed early chronic rejection may reflect an inability to recover from acute rejection.
    Type of Medium: Electronic Resource
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  • 16
    ISSN: 1434-601X
    Keywords: PACS: 25.70.Hi Transfer reactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: One and two neutron transfer has been measured in the heaviest asymmetric nuclear system with semi magic nuclei showing superfluid properties, in 206Pb+118Sn collisions at an energy well below the Coulomb barrier with scattering orbits covering the largest angles. Particle-γ coincidence techniques using 5 Euroball-Cluster detectors (EB) combined in a set-up with the Heidelberg-Darmstadt NaI-Crystal Ball (CB) have been used. Transfer channels are identified with EB via their known γ-decays of the lowest excited states. Using the unique feature of the set-up with the CB, transfer to well defined final states with known quantum numbers (without feeding) are selected using the high efficiency multiplicity filter of the CB (no second γ-ray). The data are analysed using the semiclassical approach and transfer probabilities are obtained. The enhancement for the two-neutron transfer populating the low lying superfluid 2+ state in 120Sn (and 116Sn), while the Pb-branch is in the groundstate is deduced by comparison with the strongest single neutron transfer transition. Large enhancements (EF ≃ 103) are observed. This is the first direct measurement of enhancement for a heavy nuclear binary system with experimentally separated levels suggesting a strong contribution from superfluid pair transfer.
    Type of Medium: Electronic Resource
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  • 17
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Reaction products corresponding to the transfer of one and several protons have been measured over a large angular range for incident energies of 380 MeV and 400 MeV in reactions of86Kr with88Sr,90Zr and92Mo. For transitions with smallQ-values (total kinetic energy loss TKEL≦10 MeV) the transfer probabilities are deduced. The magnitudes and slopes of these probabilities as function of the distance of closest approach between two nuclei are discussed. The results for single proton transfer are well described by tunneling, whereas the transfer of two and more nucleons into low lying states of the final nuclei seems to be influenced by intermediate transfer steps with larger TKEL. The data give the possibility to discuss the relation between deep-inelastic and quasi-elastic processes. The deep-inelastic data are analyzed successfully by including deformations, charge transfer and statistical fluctuations into the frictional model of Gross and Kalinowski.
    Type of Medium: Electronic Resource
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  • 18
    ISSN: 1434-601X
    Keywords: 24.10.−i ; 25.70.Cd
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The elastic and inelastic scattering and the neutron transfer have been measured for the systems12C +12C and13C +12C at 20MeV/N up to θcm= 60° with theQ3D -spectrometer. The angular distributions of the elastic scattering show an enhanced cross section at angles larger than 40°. It can be identified as refractive scattering with the clear signature of a nuclear rainbow.L-cut-off calculations show that these contributions come fromL-values which are significantly lower than the grazingL-value. The deflection function has a broad minimum in thisL-range which is typical for rainbow scattering. TheS-matrix is decomposed by a phenomenological parametrization into a refractive and a diffractive part. The interference of these amplitudes plays an important role in the rainbow enhancement. The spatial localization of the refractive scattering is deduced from the turning points of the corresponding trajectories; a localization between 2.5 fm and 4 fm is found. Semi-classical calculations with complex trajectories in the single-turning-point approximation show good agreement with the quantummechanical calculations. Refractive contributions are not observed in the inelastic scattering. This can be explained by reducing the strength of the conventional collective form factor in the internal region. In contrast to this the enhancement at large angles is seen in the one-neutron transfer channels where the refractive scattering is dominant. This is the first observation of such contributions to heavy-ion transfer reactions.
    Type of Medium: Electronic Resource
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  • 19
    ISSN: 1434-601X
    Keywords: 21.10.Dr ; 25.70.Cd ; 27.20.+ n
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The mass of10Li has been measured with two different reactions:9Be(13C,12N)10Li,E Lab=336 MeV, and13C(14C,17F)10Li,E Lab=337 MeV. The mass excess of 33.445(50) MeV is deduced from theQ-value measurement.10Li is found to be particle-unstable with respect to one-neutron emission by 0.42(5) MeV. In the analysis of the first reaction a low lying excited state is found at 0.38(8) MeV. This state and the ground state can be most probably identified as the 1+/2+-doublet coupled from the [π 1p3/2 ⊗ν 1p 1/2] configuration, the 1+-state being the ground state. The (13C,12N)-reaction populates the 1+-state strongly due to a spin-isospin-flip character of the dominant part of the transition amplitude. The 2+-member corresponds to the mass given by Wilcox et al. A second excited state is observed at 4.05(10) MeV with a width of 0.7(2) MeV, it can be associated with theν 1d 5/2-strength. The second reaction is fully supporting the interpretation of the ground state doublet. The excited state at 4.05 MeV is not observed in this reaction and indeed it should not, because the reaction does not populate in first order excited neutron configurations. The levels are well described by mean field calculations including pairing correlations. The lowest resonance in the calculations is theν 1/2−-configuration, whereas theν 1/2+-configuration shows at the neutron threshold a strong non-resonant contribution.
    Type of Medium: Electronic Resource
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  • 20
    ISSN: 1434-601X
    Keywords: 24.10.-i ; 24.10.Eq ; 24.20.Ht ; 25.70.Cd
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Elastic, inelastic scattering as well as one-neutron transfer channels have been measured over a wide angular range for systems16O+16O at the incident energy of 350 MeV and20Ne+12C at 390 MeV, respectively, using the Q3D magnetic spectrometer. In both cases differential cross sections have been measured down to about 50 nb/sr (or dσ/dσ R≤10−4) at large angles. For the16O+16O system refractive contributions are found at the level of these cross sections, whereas in the20Ne+12C case a steeper decrease of the differential cross section with the angle is observed and the refractive contribution can not be determined. The elastic scattering data have been analyzed using standard Woods-Saxon potentials and potentials calculated in different versions of the double-folding model. Some properties of these potentials are tested in the calculations for inelastic scattering and one-neutron transfer within the DWBA. With the refractive pattern observed for the16O+16O system, the scattering and transfer data are found to be sensitive to the interaction potential at small internuclear distances down to about 2.5 fm.
    Type of Medium: Electronic Resource
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