806 research outputs found
Pairing-excitation versus intruder states in 68Ni and 90Zr
A discussion on the nature of the 0+ states in 68Ni (Z=28, N=40) is presented
and a comparison is made with its valence counterpart 90Zr (Z=40, N=50).
Evidence is given for a 0+ proton intruder state at only ~2.2 MeV excitation
energy in 68Ni, while the analogous neutron intruder states in 90Zr reside at
4126 keV and 5441 keV. The application of a shell-model description of 0+
intruder states reveals that many pair-scattered neutrons across N=40 have to
be involved to explain the low excitation energy of the proton-intruder
configuration in 68Ni.Comment: 10 pages, 2 figures, 1 tabl
Aprotinin reduces cardiac troponin I release and inhibits apoptosis of polymorphonuclear cells during off-pump coronary artery bypass surgery
Objectives: In addition to blood-sparing effects, aprotinin may have cardioprotective and anti-inflammatory effects during cardiopulmonary bypass-assisted cardiac surgery. In this study, the authors examined whether aprotinin had cardioprotective and/or anti-inflammatory effects in patients undergoing off-pump coronary artery bypass grafting. Design: A prospective randomized clinical trial. Setting: University hospital. Participants: Fifty patients were randomized to control (n = 25) or aprotinin treatment (n = 25) groups. Interventions: Aprotinin was given as a loading dose (2 x 10(6) KIU) followed by a continuous infusion at 5 x 10(5) KIU/h until skin closure. Measurements and Main Results: Blood samples for cardiac troponin I; interleukin-6, interleukin-8, and interleukin-10; tumor necrosis factor a; and elastase were taken after anesthesia induction, completion of revascularization, and 6 hours, 12 hours, and 24 hours after revascularization. Blood samples were taken to assess for apoptosis in polymorphonuclear cells. Baseline plasma levels for cardiac troponin I did not differ between groups but were significantly lower in aprotinin-treated patients at the time of revascularization (P = 0.03) and 6 hours (p = 0.004) and 24 hours (p = 0.03) later. Aprotinin significantly reduced apoptosis in polymorphonuclear cells compared with control-treated patients (p = 0.04). There were no differences in plasma cytokine or elastase levels between groups. Conclusions: The authors conclude that aprotinin reduces perioperative cardiac troponin I release and attenuates apoptosis in polymorphonuclear cells but has no significant effects on plasma cytokine levels in patients undergoing off-pump coronary artery bypass graft surgery
Alpha Decay Hindrance Factors: A Probe of Mean Field Wave Functions
A simple model to calculate alpha-decay Hindrance Factors is presented. Using
deformation values obtained from PES calculations as the only input, Hindrance
Factors for the alpha-decay of Rn- and Po-isotopes are calculated. It is found
that the intrinsic structure around the Fermi surface determined by the
deformed mean field plays an important role in determining the hindrance of
alpha-decay. The fair agreement between experimental and theoretical Hindrance
Factors suggest that the wave function obtained from the energy minima of the
PES calculations contains an important part of the correlations that play a
role for the alpha-decay. The calculated HF that emerges from these
calculations render a different interpretation than the commonly assumed
n-particle n-hole picture.Comment: 7 pages, 9 figure
Off-line studies of the laser ionization of yttrium at the IGISOL facility
A laser ion source is under development at the IGISOL facility, Jyvaskyla, in
order to address deficiencies in the ion guide technique. The key elements of
interest are those of a refractory nature, whose isotopes and isomers are
widely studied using both laser spectroscopic and high precision mass
measurement techniques. Yttrium has been the first element of choice for the
new laser ion source. In this work we present a new coupled dye-Ti:Sapphire
laser scheme and give a detailed discussion of the results obtained from laser
ionization of yttrium atoms produced in an ion guide via joule heating of a
filament. The importance of not only gas purity, but indeed the baseline vacuum
pressure in the environment outside the ion guide is discussed in light of the
fast gas phase chemistry seen in the yttrium system. A single laser shot model
is introduced and is compared to the experimental data in order to extract the
level of impurities within the gas cell.Comment: 18 pages submitted to NIM
Abrupt changes in alpha decay systematics as a manifestation of collective nuclear modes
An abrupt change in decay systematics around the N=126 neutron shell
closure is discussed. It is explained as a sudden hindrance of the clustering
of the nucleons that eventually form the particle. This is because the
clustering induced by the pairing mode acting upon the four nucleons is
inhibited if the configuration space does not allow a proper manifestation of
the pairing collectivity.Comment: 6 pages, 3 figures, submitted to Phys. Rev. C, a few new references
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A Second Generation Radioactive Nuclear Beam Facility at CERN
The proposed Superconducting Proton Linac (SPL) at CERN would be an ideal driver for a proton-driven second-generation Radioactive Nuclear Beam facility. We propose to investigate the feasibility of constructing such a facility at CERN close to the present PS Booster ISOLDE facility. The existing ISOLDE facility would be fed with a 10 micro-amps proton beam from SPL, providing the physics community with a low-intensity experimental area. A second, new facility would be built with target stations deep underground, permitting proton beam intensities of more than 100 micro-amps. The secondary beams can be post-accelerated to 20-100 MeV/u and there will be a storage ring complex and large segmented detectors in the experimental area. Also, benefits from a muon-ion collider or from merging the ions and muons should be investigated. Since the antiproton decelerator would be nearby, the opportunities for antiprotonic radioactive atom studies should be pursued as well
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